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Foundations of Care

Oct 03, 202474 min read

VIII: Fluids and Electrolytes

Electrolytes are substances that, on dissolving in solution, ionizes; that is, some of its molecules split or dissociate into electrically charged atoms or ions. The metric system is used to measure volumes of fluids; liters (L) or milliliters (mL). The unit of measure that expresses the “combining activity” of an electrolyte is the milliequivalent (mEq). One mEq of any cation (positive ion) reacts chemically with one mEq of any anion (negative ion). They provide information about the number of anions or cations available to combine with other anions or cations.

Fluids are stored in different body compartments, and each compartment contains electrolytes. To function normally, body cells must have fluids and electrolytes in the right compartments in the right amounts. Homeostasis must exist; the number of cations and anions must be the same. Whenever an electrolyte moves out of a cell, another electrolyte moves in to take its place. Each compartment is divided by a semipermeable membrane:

  1. Intravascular compartment: fluids inside blood vessels. This contains ~6% of total body fluid.
  2. Intracellular compartment: fluids inside cells. This compartment has the most volume at ~70% of total body fluid.
  3. Extracellular compartment: fluids outside cells. This includes the interstitial fluid (~22%), which is fluid between cells (sometimes called the third space), blood, lymph, bone, connective tissue, and water; and transcellular fluid (~2%).

Body Fluids

Body fluids are responsible for transporting nutrients and removing waste products from cells.

  • Total body fluid (intracellular and extracellular) amounts to about 60% of body weight in adults, 55% in older adults, and 80% in infants. Due to lowered and heightened fluid composition of the elderly and infants, they are at higher risk for fluid-related problems.

Fluid Imbalance

Infants and older adults need to be closely monitored for fluid imbalances when at risk.

  • Body fluids consist of water and dissolved substances. The largest single fluid constituent of the body is water. Some substances, such as glucose, urea, and creatinine, do not dissociate in solution; that is, they do not separate from their complex forms into simpler substances when they are in solution. Other substances do dissociate, such as sodium chloride which separates into two elements in solution.

Fluid Shifting

  1. Third-Spacing refers to the accumulation and sequestration of trapped extracellular fluid in an actual or potential body space as a result of disease or injury. This trapped fluid represents a volume loss and is unavailable for normal physiological processes. These spaces include the pericardial, pleural, peritoneal, or joint cavities; the bowel; the abdomen; or within soft tissues after trauma or burns.
    • Assessing intravascular fluid loss caused by this type of shifting is difficult to assess. Fluid is not excreted, so alterations in weight, intake, and output is not apparent until after organ malfunction occurs.
  2. Edema: the excess accumulation of fluid in the interstitial space; results from alterations in oncotic pressure, hydrostatic pressure, capillary permeability, and lymphatic obstruction (discussed in [[#|#Fluid Transport]]).
    • Localized edema can result from trauma (from accidents, surgery), localized inflammatory processes, or burns.
    • Generalized edema, also called anascara, is an accumulation of fluid in the interstitial space throughout the body and results as a result of cardiac or renal conditions, or liver failure.

Fluid Transport

  1. Diffusion: a solute spreads through a solution or solvent, moving from higher concentration to lower concentration. A permeable membrane allows substances to pass through without restriction. A selectively permeable membrane allows some solutes to pass through without restriction, but prevents other solutes from passing freely. This occurs within and between fluid compartments if the membranes are permeable with the diffusing substances.
  2. Osmosis
  3. Filtration: the movement of solutes and solvents through hydrostatic pressure, moving from an area of higher pressure to an area of lower pressure.
  4. Hydrostatic Pressure: a force exerted by the weight of a solution. This is the driving force for filtration, where high pressure compartments “push” solutes and solvents into lower pressure compartments.
    • A prime example of hydrostatic pressure is at the arterial end of capillaries, where hydrostatic pressure exceeds osmotic pressure and fluids and diffusible solutes move out of the capillary (e.g. oxygen from hemoglobin fuels cells) and the venous end of capillaries, where osmotic pressure exceeds hydrostatic pressure and pulls solutes and fluids into the capillary (e.g. waste products exit cells and enter the blood).
  5. Osmolality: the number of osmotically active particles per kilogram of water; it is the concentration of a solution. In the body, osmotic pressure is measured in milliosmoles (mOsm). The normal osmolality of plasma is 275 to 295 mOsm/kg (275 to 295 mmol/kg). This is the reference point for isotonicity of IV solutions.

Movement of Body Fluid

Cell membranes and capillary walls separate body compartments. Cell membranes are selectively permeable, and permit the movement of water and solutes through several forces. Higher concentrations of solutes produce more forces that move fluid and solutes from the compartment.

  1. In the case of isotonic solutions, both sides of a selectively permeable membrane have equal in concentration. Very little osmosis occurs as both sides have the same osmolality.
  2. In the case of hypotonic solutions: a solution, if lower in osmolality than another, is hypotonic to that solution; for example, IV solutions with an osmolality of less than 275 mOsm/L is considered hypotonic. Osmosis occurs, “hydrating” the cells.
  3. In the case of hypertonic solutions: a solution, if higher in osmolality than another, is hypotonic to that solution; for example, IV solutions with an osmolality of more than 295 mOsm/L is considered hypertonic. Osmosis occurs, “dehydrating” the cells.
  4. Osmotic pressure is produced by the concentration of solutes in a solution. These are the “fighting” pressures across a semipermeable membranes.
  5. Active transport is utilized by the body when moving electrolytes against the concentration gradient or osmosis. Metabolic processes in the cell utilize energy to allow this transport to occur. This includes sodium, potassium, calcium, iron, and hydrogen; some of the sugars, and the amino acids.

Fluid Intake and Output

Water normally enters the body through three sources: oral intake of fluids, foods (which contain water), and through the oxidation of ingested foods, e.g., the formation of 10 mL of water as a byproduct of the metabolism of 100 calories of fat, carbohydrates, or proteins. Water exits the body primarily through urine, via the kidneys. The kidneys play a major role in regulating fluid and electrolyte balance by adjusting the amount of fluid and electrolytes in the urine. It excretes the largest quantity of fluid.

  • Water loss that cannot be measured is collectively coined as insensible loss, mostly attributed to water lost through moisture released from the lungs when breathing. This rate of loss varies based on depth and respiration.
  • A large volume of electrolyte-containing liquids moves into the gastrointestinal tract, but this is almost entirely reabsorbed. A problem arises when severe diarrhea causes the loss of large quantities of fluids and electrolytes.
  • Many organs contribute to balancing fluid content, and normal functioning for all of them is necessary to achieve and maintain fluid balance.

Diarrhea

The client with diarrhea is at high risk for a fluid and electrolyte imbalance.

SourceAmountOutputAmount
Ingested Water1200 - 1500 mLKidneys1500 mL
Ingested Food800 - 1100 mLInsensible Loss (Skin)600 - 800 mL
Metabolic Oxidation300 mLInsensible Loss (Lungs)400 - 600 mL
GI Tract100 mL
Total2300 - 2900 mLTotal2600 - 3000 mL

Fluid and Electrolyte Homeostasis

The concentration and composition of body fluids must be nearly constant. Fluids and electrolytes exist together in solution; when either fluids or electrolytes are deficient, substances must be replaced through the intake of food and water or by therapy (e.g. IV solutions and medications). When excessive, therapy focuses on aiding in excretion (e.g. diuretics).

  • The kidneys plays a major role in controlling this balance.
  • The adrenal glands atop the kidneys also contribute to controlling extracellular fluids by regulating the amount of sodium reabsorbed by the kidneys.
  • Antidiuretic hormone from the pituitary gland regulates the osmotic pressure of extracellular fluid by regulating the amount of water reabsorbed by the kidneys.

Nursing Intervention

If the client has a fluid or an electrolyte imbalance, the nurse must closely monitor the client’s cardiovascular, respiratory, neurological, musculoskeletal, renal, integumentary, and gastrointestinal status.

Fluid Volume Deficit

“Dehydration” occurs when fluid intake does not meet the fluid needs of the body. The treatment goal is to restore fluid volume, replace electrolytes as needed, and eliminate the cause of the imbalance.

Depending on the type of fluid and/or electrolyte loss, fluid volume deficits can be classified as:

TypeDescriptionResult
Isotonic Dehydration; “Hypovolemia”Fluids and electrolytes are lost equally. The most common form. Caused by inadequate intake, fluid shifting, and excessive loss of isotonic body fluids.Decreased circulating blood volume and inadequate tissue perfusion.
Hypertonic DehydrationFluid loss is greater than electrolyte loss. Electrolyte concentration in extracellular spaces increases, which draws fluid from intracellular spaces. Caused by conditions that increase fluid loss, e.g. excessive perspiration, hyperventilation, ketoacidosis, prolonged fevers, diarrhea, early-stage kidney disease, and diabetes insipidus.Cellular dehydration and shrinkage as intracellular fluids move into the plasma and interstitial fluid spaces.
Hypotonic DehydrationElectrolyte loss is greater than fluid loss. Electrolyte concentration in intracellular spaces increases, which draws fluid into intracellular spaces. Caused by chronic illness, excessive hypotonic fluid replacement, kidney disease, and chronic malnutrition.Cellular swelling occurs as plasma and interstitial fluid enters the cells.

Assessment

  1. Cardiovascular:
    • Thready, increased pulse rate; diminished peripheral pulses
    • Decreased blood pressure and orthostatic hypotension
    • Flat neck and hand veins in dependent positions
    • Decreased central venous pressure
    • Dysrhythmias
  2. Respiratory:
    • Increased rate and depth of respirations
    • Dyspnea
  3. Neuromuscular:
    • Decreased CNS activity (lethargy to coma)
    • Skeletal muscle weakness
    • Fever (depending on amount of loss)
  4. Renal: decreased urine output
  5. Integumentary
    • Dry skin with poor turgor (tenting)
    • Dry mouth
  6. Gastrointestinal:
    • Decreased motility and bowel sounds
    • Constipation
    • Decreased body weight
    • Thirst
  7. Laboratory Findings: increased serum osmolality (concentration), hematocrit, BUN, sodium, and specific gravity

Intervention

Prevent further fluid loss. Return (increase) fluid compartment volumes to normal ranges. Oral rehydration therapy is used if possible, but IV fluid replacement if dehydration is severe. Monitor the patient’s intake and output.

  • IV solutions used for different types of dehydration varies. Generally, use isotonic solutions for isotonic dehydration, hypertonic solutions for hypotonic dehydration, and vice versa.
  • If possible, treat etiology using medications such as antidiarrheals, antimicrobials, antiemetics, and antipyretics to correct the cause and treat symptoms.
  • Be prepared to administer medications to treat electrolyte imbalance, if present.

Fluid Volume Excess

“Overhydration” or fluid overload. The goal of treatment is to restore fluid balance, correct electrolyte imbalances (if present), and eliminate or control the underlying cause of the overload. The types are the same as in a deficit, but reversed:

TypeDescriptionResult
Isotonic OverhydrationExcessive fluid in the extracellular fluid compartment. Also known as “hypervolemia”. This may be caused by poorly regulated IV therapy, kidney disease, and long-term corticosteroid therapy.Circulatory overload and interstitial edema occurs; this can cause poor cardiac function, heart failure, and pulmonary edema in severe cases.
Hypertonic OverhydrationExcessive electrolytes (mainly sodium) in extracellular fluid. This rarely occurs, and is caused by excessive sodium consumption, rapid hypertonic saline infusion, and excessive sodium bicarbonate therapy.High solute concentration in extracellular fluid pulls fluid from intracellular space, leading to contraction of intracellular fluid.
Hypotonic OverhydrationWater intoxication, where excessive fluid enters extracellular space. This may be caused by early kidney disease, heart failure, SIADH, inadequately controlled IV therapy, isotonic fluid loss treated with hypotonic fluids, and irrigation of wounds and body cavities with hypotonic fluids.Fluid then enters intracellular space (because it now has higher electrolyte concentration), and all body fluid compartments expand. Electrolytes become imbalanced.

Assessment

A client with AKI, CKD, or HF is at high risk for FVE.

  1. Cardiovascular:
    • Bounding, increased pulse
    • Elevated blood pressure
    • Distended neck and hand veins
    • Elevated central venous pressure
    • Dysrhythmias
  2. Respiratory:
    • Increased respiratory rate with shallow respirations
    • Dyspnea
    • Moist crackles upon auscultation
  3. Neuromuscular:
    • Altered level of consciousness
    • Skeletal muscle weakness
    • Headache, visual disturbances
    • Paresthesias
  4. Renal: increased urine output (if compensation is present). If the cause of overload is from kidney damage, then urine output is decreased.
  5. Integumentary:
    • Pale, cool skin
    • Pitting edema in dependent areas
  6. Gastrointestinal:
    • Increased motility
    • Diarrhea
    • Increased body weight
    • Liver enlargement
    • Ascites
  7. Laboratory Findings: decreased serum osmolality, hematocrit, BUN, sodium, and specific gravity.

Interventions

Prevent further fluid overload and restore normal fluid balance.

  • Administer diuretics; osmotic diuretics may be initially used to prevent severe electrolyte imbalances.
  • Restrict fluid and sodium intake as prescribed.
  • Monitor intake and output; monitor weight.
  • Monitor electrolyte values and prepare to administer medication if an imbalance is present.

Hypokalemia

Normal Serum Potassium Level: 3.5 to 5.0 mEq/L (3.5 to 5.0 mmol/L)

Hypokalemia is a serum potassium deficiency, dropping below the lower threshold of 3.5 mEq/L. This is a life-threatening condition as every body system becomes affected. It may be caused by:

  1. Actual loss of potassium:
    • Excessive use of medications such as diuretics, corticosteroids, or inhaled albuterol
    • Increased secretion of aldosterone, such as in Cushing’s syndrome: aldosterone saves sodium by excreting potassium in its place
    • Vomiting, diarrhea
    • Wound drainage, particularly when gastrointestinal
    • Prolonged nasogastric suction
    • Excessive diaphoresis (abnormal sweating)
    • Kidney disease impairing potassium reabsorption
  2. Inadequate intake of potassium: from fasting or being on NPO status.
  3. Movement of potassium from extracellular to intracellular spaces:
    • Alkalosis
    • Hyperinsulinism
  4. Dilution of serum potassium:
    • Water intoxication
    • IV therapy with potassium-deficient solutions

Assessment Data

  1. Cardiovascular:
    • Thready, weak, irregular pulse; weak peripheral pulses
    • Orthostatic hypotension
    • Dysrhythmias
  2. Respiratory: shallow, ineffective respirations that result from profound muscle weakness of the muscles of respiration. This produces diminished breath sounds
  3. Neuromuscular:
    • Anxiety, lethargy, confusion, coma
    • Skeletal muscle weakness, leg cramps, deep tendon hyporeflexia, loss of tactile discrimination, and paresthesias
  4. Gastrointestinal: decreased motility, hypoactive to absent bowel sounds; paralytic ileus
  5. Laboratory Findings:
    • Potassium studies show a level of <3.5 mEq/L
    • Electrocardiogram changes: ST depression; shallow, flat, or inverted T waves; and prominent U waves

Analyzing Cues

A client with gastroenteritis has been vomiting and having diarrhea for the past 3 days. On admission to the hospital, the client complains of weakness and some leg and abdominal cramping. The client’s respirations are shallow and the pulse is thready. The client’s cardiac rhythm on the monitor screen shows an additional prominent wave following each T wave, indicating the presence of U waves. The nurse considers the client’s health problem, the effects and implications of losing fluid through vomiting and diarrhea for 3 days, analyzes the client cues, and interprets these cues as indicating an electrolyte imbalance, specifically hypokalemia.

Interventions

Monitor the patient’s potassium level. Administer potassium supplements orally or intravenously as prescribed.

  • Oral potassium supplements may cause nausea and vomiting and should not be taken on an empty stomach. If the client complains of abdominal pain, distention, nausea, vomiting, diarrhea, or gastrointestinal bleeding, the supplement may need to be discontinued.
  • Liquid potassium chloride can also be used, but has an unpleasant taste, and should be taken with juice or other liquids.
  • Intravenous potassium is never given via IVP, IM, or SC. Use an infusion pump. A dilution of not more than 1 mEq/dL (1 mmol/dL) is recommended. Potassium instilled into IV bags should be rotated and inverted to ensure distribution of potassium, and properly labeled.
    • Infusion rate should never exceed 20 mEq/hr and is recommended to be infused at around 5 to 10 mEq/hr. Anything more than 10 mEq/hr warrants cardiac monitoring.
    • Potassium infusion can cause phlebitis; the nurse should frequently assess the IV site for signs of phlebitis or infiltration. Infusion should be stopped immediately if complications arise. Potassium chloride can act as a vesicant and extravasation may result in local tissue necrosis.
    • Rapid administration of potassium can result in cardiac arrest.
    • Assess the patient’s renal function prior to administering potassium. Monitor I&O during administration.

Potassium Replacement via IV

Potassium replacement is safest when infused through a central line due to the high incidence of IV infiltration. Potassium is never administered by IV push, intramuscular, or subcutaneous routes. IV potassium is always diluted and administered using an infusion device!

Hyperkalemia

Hyperkalemia is a serum potassium level that exceeds 5.0 mEq/L (5.0 mmol/L). This may be caused by:

  1. Excessive potassium intake: overingestion or administration of potassium-containing foods or medications, e.g. potassium chloride or salt substitutes.
  2. Decreased potassium excretion: from potassium-sparing (retaining) diuretics, kidney disease, or adrenal insufficiency, such as in Addison’s disease.
  3. Movement of potassium from the intracellular to extracellular fluid as a result of tissue damage, acidosis, hyperuricemia, or hypercatabolism.

Potassium imbalance can cause life-threatening cardiac dysrhythmias. Monitor the client closely.

Assessment

  1. Cardiovascular:
    • Slow, weak, irregular heart rate
    • Decreased blood pressure
  2. Respiratory: profound weakness of the skeletal muscles leading to respiratory failure
  3. Neuromuscular:
    • Early manifestations: muscle twitches, cramps, paresthesias (tingling and burning followed by numbness in the extremities and around the mouth)
    • Late manifestations: profound weakness e.g. ascending flaccid paralysis in the arms and legs (trunk, head, and respiratory muscles become affected when a lethal potassium level is reached)
  4. Gastrointestinal:
    • Increased motility; hyperactive bowel sounds; resultant diarrhea
  5. Laboratory Findings:
    • Potassium studies show a level of >5.0 mEq/L
    • Electrocardiogram changes: tall peaked T waves, flat P waves, widened QRS complexes, and prolonged PR intervals.

Interventions

Terminate the source of excessive potassium as soon as possible and continue monitoring the patient’s potassium levels.

  • Discontinue IV potassium (KVO) and withhold oral potassium supplements. Initiate a potassium-restricted diet. Instruct the patient against the use of potassium-containing substances and salt substitutes.
  • Potassium-excreting diuretics may be administered for patients without renal damage. Monitor the patient’s potassium levels closely when taking these medications.
  • If renal function is impaired, sodium polystyrene sulfonate (oral or rectal) is a cation-exchange resin that promotes the reabsorption of sodium and excretion of potassium.
  • Dialysis is used for severe hypokalemia. To avert myocardial excitability from severe hyperkalemia, IV calcium may be given.
  • IV hypertonic glucose with insulin moves excess potassium into cells.
  • If a patient with a potassium imbalance is receiving a blood transfusion, use fresh blood if possible. Transfusions of stored blood may elevate the potassium levels due to the breakdown of older blood cells, releasing potassium.
  • Teach the client to avoid foods high in potassium: all meats, fish, soy products, veggie burgers, vegetables, fruits, milk and yogurt, and nuts

Hyponatremia

Normal Serum Sodium Level: 135 to 145 mEq/L (135 to 145 mmol/L)

Imbalances related to sodium is closely tied with fluid volume imbalances. This may be caused by:

  1. Increased sodium excretion: diaphoresis, diuretics, vomiting, diarrhea, wound drainage (especially gastrointestinal), kidney disease, and decreased secretion of aldosterone (the salt-saving hormone).
  2. Inadequate sodium intake: fasting/NPO status, low-salt diet
  3. Dilution of serum sodium: excessive ingestion of or irrigation with hypotonic fluids; kidney disease; freshwater drowning; SIADH; hyperglycemia; heart failure

Assessment

  1. Cardiovascular: symptoms depend on vascular volume.
    • Normovolemic: rapid pulse rate, normal blood pressure
    • Hypovolemic: thready, weak, rapid pulse rate; hypotension; flat neck veins; normal or low central venous pressure
    • Hypervolemic: rapid, bounding pulse; blood pressure is normal or elevated; normal or elevated central venous pressure
  2. Respiratory: shallow, ineffective respiratory movement is a late manifestation related to skeletal muscle weakness.
  3. Neuromuscular: generalized skeletal muscle weakness that is worse in the extremities; diminished deep tendon reflexes
  4. Central Nervous System:
    • Headache
    • Personality changes
    • Confusion
    • Seizures
    • Coma
  5. Gastrointestinal:
    • Nausea
    • Increased motility and hyperactive bowel sounds
    • Abdominal cramping and diarrhea
  6. Renal: increased urinary output
  7. Integumentary: dry mucous membranes
  8. Laboratory Findings: <135 mEq/L serum sodium concentration; decreased urinary specific gravity

Interventions

Interventions depend on the cause and accompanying conditions:

  • If a fluid volume deficit (hypovolemia) is present, IV sodium chloride infusions are administered to restore sodium content and fluid volume.
  • If a fluid volume excess (hypervolemia) is present, osmotic diuretics may be prescribed to promote the excretion of water, but not sodium.
  • Treatment depends on whether the hyponatremia is chronic or acute; if the imbalance is severe, hospitalization may be required to closely monitor sodium levels, avoid rapid sodium shifts, and monitor the patient’s neurological status.
  • A sudden correction of hyponatremia may cause osmotic demyelination (sudden shift of fluid from the brain to circulation results in dehydration and destruction of myelin in the white matter).
  • If hyponatremia is caused by SIADH, medications that antagonize ADH may be administered.
  • Instruct the client to increase oral sodium intake as prescribed, and inform the client about the foods to include in the diet: sodium chloride (table salt), milk, beets, celery, some drinking waters, food products (Worcestershire sauce, soy sauce, onion salt, garlic sault, bouillon cubes), processed meats, canned soups and vegetables, processed baked foods, and fast foods.
  • If the client is taking lithium, monitor the lithium level, because hyponatremia can reduce lithium excretion and therefore potential toxicity.

Hyponatremia precipitates lithium toxicity in a client taking this medication.

Hypernatremia

A serum sodium level that exceeds 145 mEq/L (145 mmol/L). This is caused by:

  1. Decreased sodium excretion: corticosteroids, Cushing’s syndrome, kidney disease, hyperaldosteronism
  2. Increased sodium intake: excessive oral sodium ingestion or administration of sodium-containing IV fluids.
  3. Decreased water intake leading to sodium concentration, from fasting or NPO status.
  4. Increased water loss leading to sodium concentration: increased rate of metabolism, fever, hyperventilation, infection, excessive diaphoresis, watery diarrhea, and diabetes insipidus.

Assessment

  1. Cardiovascular: heart rate and blood pressure responsive to vascular volume status
  2. Respiratory: pulmonary edema if hypervolemia is present
  3. Neuromuscular: an early manifestation of spontaneous muscle twitches, and later skeletal muscle weakness and diminished deep tendon reflexes (same as hyponatremia)
  4. Central Nervous System: altered cerebral function (most common)
    • If normovolemic or hypovolemic, agitation, confusion, and seizures
    • If hypervolemic, lethargy, stupor, and coma
  5. Gastrointestinal: extreme thirst
  6. Renal: decreased urine output
  7. Integumentary: dry and sticky tongue and mucous membranes; dry and flushed skin; presence or absence of edema depending on fluid volume changes.
  8. Laboratory Findings: serum sodium level more than 145 mEq/L (145 mmol/L); increased urine specific gravity

Interventions

  • If fluid loss is the cause, prepare to administer IV infusions to restore fluid volume.
  • If inadequate renal excretion of sodium is the cause, prepare to administer diuretics that promote sodium excretion.
  • Restrict sodium and fluid intake as prescribed.
  • In some situations, IV fluid of D5W will be prescribed to lower the sodium level. If the client has diabetes, monitor glucose closely for hyperglycemia.

Hypocalcemia

Normal Serum Calcium Level: 9 to 10.5 mg/dL (2.25 to 2.75 mmol/L)

Hypocalcemia is a serum calcium level lower than 9.0 mg/dL (2.25 mmol/L). Its causes include:

  1. Inhibition of calcium absorption from the gastrointestinal tract: inadequate calcium intake, lactose intolerance (lactose enhances calcium absorption[citation needed]), malabsorption syndromes e.g. celiac sprue or Crohn’s disease, inadequate vitamin D intake, and end-stage kidney disease.
  2. Increased calcium excretion: kidney disease (polyuric phase), diarrhea, steatorrhea, and wound drainage (especially gastrointestinal).
  3. Conditions that decrease the ionized fraction of calcium: hyperproteinemia, alkalosis, medications (calcium chelators or binders), acute pancreatitis, hyperphosphatemia, and removal or destruction of the parathyroid glands.

Assessment

  1. Cardiovascular:
    • Decreased heart rate
    • Hypotension
    • Diminished peripheral pulses
  2. Respiratory: not directly affected, but failure or arrest may occur from muscle tetany or seizures affecting the respiratory muscles.
  3. Neuromuscular:
    • Anxiety; irritability
    • Irritable skeletal muscles: twitches, cramps, tetanus, seizures; hyperactive deep tendon reflexes
    • Paresthesias followed by numbness that may affect the lips, nose, and ears in addition to the limbs
    • Chvostek’s Sign: contraction of facial muscles in response to a light tap over the facial nerve in front of the ear.
    • Trousseau’s Sign: a carpal spasm induced by inflating a blood pressure cuff above the systolic pressure for a few minutes.
  4. Renal: urinary output varies depending on the cause
  5. Gastrointestinal: increased gastric motility; hyperactive bowel sounds; cramping, diarrhea
  6. Laboratory Findings: serum calcium level less than 9.0 mg/dL (2.25 mmol/L); ECG changes: prolonged ST and QT intervals

Interventions

  • Check albumin levels. Calcium binds to proteins, most prominently to albumin. A low albumin level may result in a reading of low serum calcium levels, despite no changes in total ionized calcium. If the client has a low albumin level, the calcium level should be corrected. It is determined through the formula . Alternatively, the ionized calcium level can be checked, which has a normal value of 4.64 to 5.28 in adults.
  • Administer calcium supplements orally or intravenously. When administering calcium intravenously, warm the injection solution to body temperature before administration. Administer slowly; monitor for ECG changes, infiltration, and hypercalcemia.
  • Administer medications that supplement calcium absorption.
    • Aluminum hydroxide reduces phosphorus levels, causing the countereffect of increasing calcium levels.
    • Vitamin D aids in the absorption of calcium from the intestinal tract.
  • Provide a quiet environment to reduce environmental stimuli.
  • Initiate seizure precautions.
  • Move the client carefully, and monitor for signs of pathologic fractures.
  • Keep 10% calcium gluconate available for treatment of acute calcium deficit.
  • Instruct the client to eat foods high in calcium: dairy products (milk, cheese, yogurt); tofu; green leafy vegetables (broccoli, collards, kale, mustard greens, turnip greens, bok choy); salmon and sardines; almonds, brazil nuts, sunflower seeds, tahini, and dried beans; blackstrap molasses.

Hypercalcemia

A serum calcium concentration that exceeds 10.5 mg/dL (2.75 mmol/L). Its causes include:

  1. Increased calcium absorption: excessive oral intake of calcium and/or vitamin D
  2. Decreased calcium excretion: kidney disease, the use of thiazide diuretics
  3. Increased bone resorption of calcium: hyperparathyroidism, hyperthyroidism, malignancy (bone destruction from metastatic tumors), and immobility
  4. Hemoconcentration: dehydration, lithium therapy, and adrenal insufficiency

Assessment

  1. Cardiovascular:
    • Increased heart rate in the early phase; bradycardia to cardiac arrest in late phases
    • Hypertension; bounding peripheral pulses
  2. Respiratory: ineffective respiratory movements as a result of profound skeletal muscle weakness.
  3. Neuromuscular:
    • Disorientation, lethargy, coma
    • Profound muscle weakness; diminished or absent deep tendon reflexes
  4. Renal: urinary output varies depending on the cause
  5. Gastrointestinal:
    • Decreased motility and hypoactive bowel sounds; constipation
    • Anorexia, nausea, abdominal distention
  6. Laboratory Findings:
    • a serum calcium level greater than 10.5 mg/dL (2.75 mmol/L)
    • Shortened ST and QT intervals; widened T wave; heart block

Interventions

Pathologic fractures are a risk for clients with calcium imbalances. Move them slowly and assist with ambulation.

  • Administer isotonic saline solutions are prescribed. Discontinue IV infusions of solutions containing calcium and oral medications containing calcium or vitamin D
  • Thiazide diuretics may be discontinued and replaced with diuretics that enhance the excretion of calcium
  • Administer medications as prescribed that inhibit calcium resorption from the bone e.g. phosphorus, calcitonin, bisphosphonates, and prostaglandin synthesis inhibitors (acetylsalicylic acid, nonsteroidal antiinflamatory medications)
  • If severe, prepare for dialysis if it does not respond to treatment.
  • Move the client carefully and monitor for signs of pathologic fracture
  • Monitor for flank or abdominal pain, and strain the urine to check for the presence of urinary stones.
  • Avoid foods high in calcium: dairy products (milk, yogurt, cheese); tofu; green leafy vegetables (broccoli, collards, kale, mustard greens, turnip greens, bok choy); salmon and sardines; almonds, brazil nuts, sunflower seeds, tahini, and dried beans; blackstrap molasses

Hypomagnesemia

Normal Serum Magnesium Level: 1.8 to 2.6 mEq/L (0.74 to 1.07 mmol/L)

Hypomagnesemia is a serum magnesium level lower than 1.8 mEq/L (0.74 mmol/L). It may be caused by:

  1. Insufficient magnesium intake: malnutrition and starvation, vomiting or diarrhea, malabsorption syndrome, Celiac disease, and Chron’s disease
  2. Increased magnesium excretion: medications such as diuretics, and chronic alcoholism
  3. Intracellular movement of magnesium: hyperglycemia, insulin administration, sepsis

Assessment

  1. Cardiovascular: tachycardia; hypertension
  2. Respiratory: shallow respirations
  3. Neuromuscular:
    • Hyperreflexia
    • Twitches, paresthesias
    • Positive Trousseau’s and Chvostek’s signs
    • Tetany, seizures
  4. Central Nervous System: irritability; confusion
  5. Laboratory Findings:
    • Serum magnesium level less than 1.8 mEq/L (0.74 mmol/L)
    • ECG changes: tall T waves, depressed ST segments

Interventions

  • Hypocalcemia frequently accompanies hypomagnesemia. Include correction of serum calcium levels in the plan of care.
  • Oral preparations of magnesium may cause diarrhea and increase magnesium loss.
  • Magnesium sulfate through IV may be prescribed in ill clients when levels are low. IM administration causes pain and tissue damage. Initiate seizure precautions, measure serum magnesium levels frequently, and monitor for diminished deep tendon reflexes (suggestive of hypermagnesemia) during administration.

Hypermagnesemia

A serum magnesium level exceeding 2.6 mEq/L (1.07 mmol/L). It may be caused by:

  1. Increased magnesium intake: the consumption of magnesium-containing antacids and laxatives, and excessive magnesium administration through IV.
  2. Decreased renal excretion of magnesium as a result of renal insufficiency.

Assessment

  1. Cardiovascular: bradycardia, dysrhythmias; arrest is possible if severe
  2. Respiratory: respiratory insufficiency if muscles of respiration are involved
  3. Neuromuscular: diminished or absent deep tendon reflexes, skeletal muscle weakness
  4. Central Nervous System: drowsiness and lethargy that progresses to a coma
  5. Laboratory Findings:
    • Serum magnesium level over 2.6 mEq/L (1.07 mmol/L)
    • ECG changes: prolonged PR interval, widened QRS complexes

Interventions

Calcium gluconate is the antidote for a magnesium overdose!

  • Diuretics are prescribed to increase renal excretion of magnesium.
  • Intravenously administered calcium chloride or calcium gluconate may be prescribed to reverse the effects of magnesium on cardiac muscle.
  • Instruct the client to restrict dietary intake of magnesium-containing foods: dark green leafy vegetables, fruits (e.g. bananas, dried apricots, and avocados), nuts (e.g. almonds, and cashews), peas and beans (legumes), seeds, soy products (e.g. soy flour and tofu), whole grains (e.g. brown rice and millet), and milk
  • Instruct the client to avoid the use of laxatives and antacids containing magnesium.

Hypophosphatemia

Normal Serum Phosphorus Level: 3.0 to 4.5 mg/dL (0.97 to 1.45 mmol/L)

Phosphorus and calcium have a reciprocal relationship in the body; a decrease in phosphorus reflects an increase in calcium and vice versa.

Hypophosphatemia is a serum level of less than 3.0 mg/dL (0.97 mmol/L). It may be caused by:

  1. Insufficient phosphorus intake: malnutrition and starvation
  2. Increased phosphorus excretion: hyperparathyroidism, malignancy, and use of magnesium-based or aluminum hydroxide-based antacid
  3. Intracellular shift: hyperglycemia, respiratory alkalosis

Assessment

Because of the accompanying imbalance of calcium with phosphate imbalances, assessment data is reflective of the opposing imbalance i.e. hypophosphatemia presents with the clinical picture of [[#Hypercalcemia#Assessment]].

Hypophosphatemia may be asymptomatic until levels become very low.

Interventions

  • Discontinue medications that contribute to low phosphorus levels.
  • Administer phosphorus orally with a vitamin D supplement. Prepare to administer phosphorus intravenously when serum phosphorus levels fall below 1 mg/dL and when the client experiences critical clinical manifestations. Phosphorus is administered slowly to prevent overcorrection.
  • Assess the renal system before administering phosphorus.
  • Move the client carefully and monitor for signs of pathologic fracture.
  • Increase the intake of phosphorus-containing foods: seeds (sunflower, pumpkin, and squash), whey, cheese, cornmeal, beans, and salt-free nuts (almonds, peanuts).
    • Decrease dietary calcium intake (refer to [[#Hypercalcemia#Interventions]]).

Hyperphosphatemia

A serum phosphorus level over 4.5 mg/dL (1.45 mmol/L). Most body systems tolerate an elevated phosphorus level well; the problems that arise are the result of the accompanying hypocalcemia that is produced with hyperphosphatemia. Its causes include:

  1. Decreased renal excretion resulting from renal insufficiency
  2. Tumor lysis syndrome
  3. Increased intake of phosphorus, including dietary intake and phosphate-containing laxatives or enemas
  4. Hypoparathyroidism

Assessment

Assessment is the same as for [[#Hypocalcemia#Assessment]] for reasons stated above.

Interventions

  • Interventions entail the management of [[#Hypocalcemia#Interventions]].
  • Administer phosphate-binding medications that increase fecal excretion of phosphorus by binding phosphorus from the food in the gastrointestinal tract.
  • Instruct the client to avoid phosphate-containing medications, including laxatives and enemas.
  • Instruct the client to decrease the intake of food that is high in phosphorus: seeds (sunflower, pumpkin, and squash), whey, cheese, cornmeal, beans, and salt-free nuts (almonds, peanuts).
  • Instruct the client in medication administration: take phosphate-binding medications, emphasizing that they should be taken with meals or immediately after meals.

Practice Questions

  1. The nurse is caring for a client with heart failure. On assessment, the nurse notes that the client is dyspneic, and crackles are audible on auscultation. What additional manifestations would the nurse expect to note if this client if excess fluid volume is present?
    • Weight loss and dry skin
    • Flat neck and hand veins and decreased urinary output
    • An increase in blood pressure and increased respirations
    • Weakness and decreased central venous pressure
  1. The nurse reviews a client’s record and determines that the client is at risk for developing a potassium deficit if which situation is documented?
    • Sustained tissue damage
    • Requires nasogastric suction
    • Has a history of Addison’s disease
    • Uric acid level of 9.4 mg/dL (557 mcmol/L)
  1. The nurse reviews a client’s electrolyte laboratory report and notes that the potassium level is 2.5 mEq/L (2.5 mmol/L). Which pattern would the nurse watch for on the electrocardiogram (ECQ) as a result of the laboratory value? Select all that apply.
    • U waves
    • Absent P waves
    • Inverted T waves
    • Depressed ST segment
    • Widened QRS complex
  1. Potassium chloride intravenously is prescribed for a client with heart failure experiencing hypokalemia. Which actions would the nurse take to plan for preparation and administration of the potassium? Select all that apply.
    • Obtain an intravenous (IV) infusion pump.
    • Monitor urine output during administration.
    • Prepare the medication for bolus administration.
    • Monitor the IV site for signs of infiltration or phlebitis.
    • Ensure that the medication is diluted in the appropriate volume of fluid.
    • Ensure that the bag is labeled with the volume of potassium in the solution.
  1. The nurse is assessing a client with a lactose intolerance disorder for a suspected diagnosis of hypocalcemia. Which clinical manifestation would the nurse expect to note in the client?
    • Twitching
    • Hypoactive bowel sounds
    • Negative Trousseau’s sign
    • Hypoactive deep tendon reflexes.
  1. The nurse is caring for a client with Chron’s disease who has a calcium level of 8 mg/dL (2 mmol/L). Which patterns would the nurse watch for on the electrocardiogram? Select all that apply.
    • Peaked T wave
    • Widened T wave
    • Prominent U wave
    • Prolonged QT interval
    • Prolonged ST segment
  1. The nurse reviews the electrolyte results of a client with chronic kidney disease and notes that the potassium level is 5.7 mEq/L (5.7 mmol/L). Which patterns would the nurse watch for on the cardiac monitor as a result of the laboratory value? Select all that apply.
    • ST depression
    • Prominent U waves
    • Tall peaked T waves
    • Prolonged ST segments
    • Widened QRS complexes
  1. Which client is at risk for the development of a sodium level of 130 mEq/L (130 mmol/L)?
    • The client who is taking diuretics
    • The client with hyperaldosteronism
    • The client with Cushing’s syndrome
    • The client who is taking corticosteroids
  1. The nurse is caring for a client with heart failure who is receiving high doses of a diuretic. On assessment, the nurse notes that the client has flat neck veins, generalized muscle weakness, and diminished deep tendon reflexes. The nurse suspects hyponatremia. Which additional sign would the nurse expect to note in a client with hyponatremia?
    • Muscle twitches
    • Decreased urinary output
    • Hyperactive bowel sounds
    • Increased specific gravity of the urine
  1. The nurse reviews a client’s laboratory report and notes that the client’s serum phosphorus (phosphate) level is 1.8 mg/dL (0.58 mmol/L). Which condition most likely caused this serum phosphorus level?
    • Malnutrition
    • Renal insufficiency
    • Hypoparathyroidism
    • Tumor lysis syndrome
  1. The nurse is reading a physician’s progress notes in the client’s record and reads that the physician has documented “insensible fluid loss of approximately 800 mL daily.” The nurse plans to monitor the client, knowing that insensible fluid loss occurs through which type of excretion?
    • Urinary output
    • Wound drainage
    • Integumentary output
    • The gastrointestinal tract
  1. The nurse is assigned to care for a group of clients. On review of the clients’ medical records, the nurse determines which client as most likely to be at risk for a fluid volume deficit?
    • A client with an ileostomy
    • A client with heart failure
    • A client on long-term corticosteroid therapy
    • A client receiving wound irrigations
  1. The nurse caring for a client with heart failure who has been receiving intravenous (IV) diuretics suspects that the client is experiencing a fluid volume deficit. Which assessment finding would the nurse note in a client with this condition?
    • Weight loss and poor skin turgor
    • Lung congestion and increased heart rate
    • Decreased hematocrit and increased urine output
    • Increased respirations and increased blood pressure
  1. On review of the clients’ medical records, the nurse determines which client as the most likely to develop fluid volume excess?
    • The client taking diuretics who has tenting of the skin
    • The client with an ileostomy from a recent abdominal surgery
    • The client who requires intermittent gastrointestinal suctioning
    • The client with kidney disease that developed as a complication of diabetes mellitus
  1. Which client is at risk for the development of a potassium level of 5.5 mEq/L (5.5 mmol/L)?
    • The client with colitis
    • The client with Cushing’s syndrome
    • The client who has been overusing laxatives
    • The client who has sustained a traumatic burn

IX: Acid-Base Balance

Hydrogen ions are what determine the pH of the body. The pH scale extends from 1 to 14, where 7 is considered as the middle ground; “neutral”. Acids (which contain hydrogen ions) decrease pH, while Bases (which have no hydrogen ions) increase pH. The pH of body fluid is normally between 7.35 to 7.45.

  1. Acids contain ions, and are produced as end products of metabolism. They “give” hydrogen ions to neutralize or decrease the strength of an acid.
  2. Bases have no ions, and “accept” ions from acids to neutralize or decrease the strength of a base or to form a weaker acid. The normal serum level of bicarbonate (HCO3-) are 21 to 28 mEq/L (21 to 28 mmol/L).

Regulatory Systems

  1. Buffers: fast-acting regulatory systems that provide immediate protection against changes in hydrogen ion concentration in the extracellular fluid. They function only to keep the pH with the narrow limits of stability when too much acid or base is released into the system. They absorb or release hydrogen ions as necessary. These function as a transport mechanism that carries hydrogen ions to the lungs. The body’s buffers are consumable; limited. Once used, the body is less able to handle further stress until they are replaced.
    • Hemoglobin System: the use of a chloride shift, where chloride moves in and out of cells in response to oxygen levels in the blood. There is an exchange between chloride inside the cell, and bicarbonate outside the cell and vice versa.
    • Plasma Protein System: functioning with the liver to vary the amount of hydrogen ions in the chemical structure of plasma proteins. These proteins have the ability to attract or release hydrogen ions.
    • Carbonic Acid-Bicarbonate System: the primary buffer system; it maintains a pH of 7.4 with a ratio of 20:1 between bicarbonate (HCO3-) and carbonic acid (H2CO3).
      • Carbonic acid concentration is controlled by the excretion of CO2 by the lungs; changes in CO2 is reflected in the rate and depth of respirations.
      • Bicarbonate concentration is controlled by the kidneys; they selectively retain or excrete bicarbonate in response to bodily needs.
    • Phosphate Buffer System: a system present in cells and body fluids, especially active in the kidneys. It acts like bicarbonate and neutralizes excess hydrogen ions.
  2. Lungs: the second defense of the body, interacting with the buffer system to maintain acid-base balance. The lungs can only act upon excess hydron ions carried by carbonic acid. Other carriers are handled by the kidneys.
    • During acidosis, respiratory rate and depth increase in an attempt to exhale acids: carbonic acid created by the neutralizing action of bicarbonate is carried to the lungs, and is reduced to CO2 and water, and exhaled.
    • During alkalosis, respiratory rate and depth decrease, retaining CO2 and increasing carbonic acid, reducing the strength of excess bicarbonate.
    • This correction takes between 10 to 30 seconds to complete.
    • The lungs can hold hydrogen ions until the deficit is corrected, or can inactive hydrogen ions, changing the ions to water molecules to be exhaled along with CO2.
  3. Kidneys: a more inclusive corrective response to acid-base disturbances than other corrective mechanisms, but much more slowly. Compensation requires a few hours to several days, but is more thorough and selective than other regulators, such as the buffers and lungs.
    • In acidosis, hydrogen ions are secreted into the tubules and combine with buffers to be excreted in the urine.
    • In alkalosis, excess bicarbonate ions move into the tubules and combine with sodium to be excreted in the urine.
    • Bicarbonate is selectively regulated in the kidneys. (a) The kidneys restore bicarbonate by excreting hydrogen ions and retaining bicarbonate ions. (2) Excess hydrogen ions are excreted in the urine in the form of phosphoric acid. (3) The alteration of certain amino acids in the renal tubules results in a diffusion of ammonia into the kidneys, which combine with excess hydrogen ions and is excreted in the urine.
  4. Potassium (K+) plays an exchange role in acid-base balance. Moving hydrogen ions into and from cells changes the potassium level (potassium movement across cell membranes is facilitated by transcellular shifting in response to acid-base patterns) i.e. potassium levels change to compensate for hydrogen ion level changes.
    • In acidosis, the body moves hydrogen ions into the cells, moving potassium out of cells. Serum potassium levels increase.
    • In acidosis, cells release hydrogen ions into the blood to increase acidity, forcing potassium back into the cells. Serum potassium levels decrease.

Respiratory Acidosis

The total number of buffer base is lower than normal, with a relative increase in hydrogen ion concentration; thus, a greater number of hydrogen ions are circulating in the blood than can be absorbed by the buffer system. It may be caused by:

  1. Primary defects in the function of the lungs or changes in normal respiration patterns.
  2. Any condition that causes an obstruction of the airway leading to hypoventilation or respiratory system depression.
CauseDescription
Asthmaspasms resulting from allergens, irritants, or emotions, resulting in ineffective gas exchange.
AtelectasisExcessive mucus collection with the collapse of alveolar sacs caused by mucous plugs, infectious drainage, or anesthetic medications, resulting in ineffective gas exchange.
Brain TraumaRespiratory depression may occur from pressure placed on the medulla oblongata or respiratory center.
BronchiectasisAbnormal dilation of the bronchial airways from inflammation, and destructive changes and weakness in the bronchial walls occur.
BronchitisInflammation causes airway obstruction, resulting in ineffective gas exchange.
Central Nervous System DepressantsSedatives, opioids, and anesthetics depress the respiratory center, leading to hypoventilation. CO2 becomes retained. Reversal of excessive sedation may require opioid antagonists.
Emphysema and COPDThe loss of alveolar sac elasticity restricts ventilation (mostly in exhalation), leading to increased CO2 levels.
HypoventilationCO2 is retained and the hydrogen ion concentration increases. Carbonic acid is retained, decreasing pH and creating an acidotic state.
PneumoniaExcess mucus production and lung congestion cause airway obstruction, resulting in inadequate gas exchange.
Pulmonary EdemaExtracellular accumulation of fluid in pulmonary tissue causes disturbances in alveolar diffusion and perfusion.
Pulmonary EmboliEmboli obstruct pulmonary arteries, resulting in airway obstruction and inadequate gas exchange.

Assessment

  1. Neurological: lethargy, confusion, dizziness, headache, coma
  2. Cardiovascular: decreased blood pressure; dysrhythmias (from hyperkalemia during compensation); warm, flushed skin (from peripheral vasodilation)
  3. Gastrointestinal: no significant findings
  4. Neuromuscular: muscle weakness and seizures
  5. Respiratory: increased rate and depth as compensation. If unable to compensate, hypoventilation and hypoxia occur

Interventions

  • Monitor for signs of respiratory distress.
  • Administer O2 as prescribed.
  • Place the client in a semi-Fowler’s position.
  • Encourage and assist the client to turn, cough, and deep-breathe.
  • Reduce restlessness by improving ventilation rather than by administering tranquilizers, sedatives, or opioids, as these further depress respirations.
  • Prepare to administer respiratory treatments as prescribed; suction the client’s airway if necessary.
  • Prepare for endotracheal intubation and mechanical ventilation if severe acidosis and CO2 levels rise above 50 mm Hg (normally 21 to 28 mm Hg) and signs of acute respiratory distress are present.

Airway Obstruction

If the client has a condition that causes an obstruction of the airway or depresses the respiratory system, monitor the client for respiratory acidosis.

Respiratory Alkalosis

A deficit of carbonic acid and a decrease in hydrogen ion concentration that results from the accumulation of base or from a loss of acid without a comparable loss of base in the body fluids. Its causes include conditions that cause overstimulation of the respiratory system:

CauseDescription
FeverCauses increased metabolism, resulting in overstimulation of the respiratory system.
HyperventilationRapid respirations causing the blowing off of carbon dioxide (CO2), leading to a decrease in carbonic acid.
HypoxiaStimulates the respiratory center in the brainstem, which causes an increase in respiratory rate in order to increase oxygen (O2); this causes hyperventilation, which results in a decrease in the CO2 level.
Overventilation by mechanical ventilatorsThe administration of O2 and depletion of CO2 can occur from mechanical ventilation, causing the client to be hyperventilated.
PainOverstimulation of the respiratory center in the brain stem results in a carbonic acid deficit.
Severe anxiety and hysteriaOften is neurogenic and related to a psychoneurosis; however, this condition leads to vigorous breathing and excessive exhaling of CO2.

Assessment

  1. Neurological: dizziness, light-headedness, confusion, headache
  2. Cardiovascular: low blood pressure, tachycardia, dysrhythmias
  3. Gastrointestinal: nausea, vomiting, diarrhea; epigastric pain
  4. Neuromuscular: tetany, numbness, tingling of extremities, hyperreflexia, seizures
  5. Respiratory: decreased respiratory rate and depth as compensation. If unable to compensate, hyperventilation occurs

Interventions

  • Monitor for signs of respiratory distress.
  • Provide emotional support and reassurance to the client.
  • Encourage appropriate breathing patterns.
  • Assist with breathing techniques and aids if needed and as prescribed; voluntary breath holding, using a rebreathing mask, CO2 breaths with rebreathing into a paper bag.
  • Provide cautious care with ventilator clients so they are not forced to take breaths too deeply or rapidly.
  • Prepare to administer calcium gluconate for tetany as prescribed.

Metabolic Acidosis

A total concentration of buffer base that is lower than normal, with a relative increase in the hydrogen ion concentration, resulting from loss of too much base and/or retention of too much acid. Its causes include:

CauseDescription
Diabetes MellitusAn insufficient insulin supply increases fat metabolism, leading to an excess accumulation of ketones or other acids; the bicarbonate ends up being depleted.
Excessive ingestion of acetylsalicylic acidIncrease in the hydrogen ion concentration.
High-fat dietRapid accumulation of the waste products of fat metabolism leads to a buildup of ketones and acids.
Insufficient metabolism of carbohydratesWhen the oxygen supply is not sufficient for the metabolism of carbohydrates, lactic acid is produced, leading to acidosis.
MalnutritionImproper metabolism causes fat catabolism, which produces ketones and acids.
Renal insufficiency, acute kidney injury, or chronic kidney diseaseIncreased retention of waste products of protein metabolism; acids increase, and bicarbonate is unable to compensate.
Severe diarrheaThe alkaline intestinal and pancreatic secretions are lost, leading to acidosis.

Assessment

  1. Neurological: lethargy, confusion, dizziness, headache, coma (same as with its respiratory counterpart)
  2. Cardiovascular: decreased blood pressure; dysrhythmias (from hyperkalemia during compensation); and cold, clammy skin (only skin presentation varies from its respiratory counterpart)
  3. Gastrointestinal: nausea, vomiting, diarrhea, abdominal pain
  4. Neuromuscular: muscle weakness, seizures
  5. Respiratory: deep, rapid respirations (compensatory action by the lungs) known as Kussmaul’s respirations.

Interventions

  • Monitor for signs of respiratory distress.
  • Monitor intake and output and assist with fluid and electrolyte replacement as prescribed.
  • Prepare to administer solutions intravenously as prescribed to increase the buffer base.
  • For diabetes mellitus and diabetic ketoacidosis (DKA), give insulin as prescribed to decrease ketosis, monitor for circulator collapse caused by polyuria (osmotic diuresis), and administer fluid volume resuscitation for DKA; monitor electrolytes, glucose, and urinary output during administration.
  • For kidney disease, dialysis may be necessary to remove waste products. A diet low in protein and high in calories decreases the resulting amount of protein waste products.

Metabolic Alkalosis

A deficit of carbonic acid and a decrease in hydrogen ion concentration that results from the accumulation of base or from a loss of acid without a comparable loss of base in the body fluids. Its causes include:

CauseDescription
DiureticsThe loss of hydrogen ions and chloride from diuresis causes a compensatory increase in the amount of bicarbonate in the blood.
Excessive vomiting or GI suctioningLeads to an excessive loss of hydrochloric acid.
HyperaldosteronismIncreased renal tubular reabsorption of sodium occurs, with the resultant loss of hydrogen ions.
Ingestion of and/or infusion of excess sodium bicarbonateCauses an increase in the amount of base in the blood.
Massive transfusion of whole bloodThe citrate anticoagulant used for the storage of blood is metabolized to bicarbonate.

Assessment

  1. Neurological: lethargy, irritability, confusion, headache
  2. Cardiovascular: low blood pressure, tachycardia, dysrhythmias (same as in respiratory alkalosis)
  3. Gastrointestinal: anorexia, nausea, vomiting
  4. Neuromuscular: tetany, tremors, tingling of extremities, muscle cramps; hypertonic muscles, seizures
  5. Respiratory: decreased respiratory rate and depth as compensation (hypoventilation)

Intervention

  • Monitor for signs of respiratory distress.
  • Prepare to administer medications and intravenous fluids as prescribed to promote the kidney excretion of bicarbonate.
  • Prepare to replace potassium as prescribed.

Arterial Blood Gases

Sample Collection

  1. Obtain vital signs.
  2. Determine if the client has an arterial line in place.
  3. Perform Allen’s test to determine the presence of collateral circulation; note that in most facilities, a respiratory therapist performs the sample collection.
  4. Assess factors that may affect the accuracy of the results, such as changes in the O2 settings, suctioning within the past 20 minutes, and the client’s activities.
  5. Provide emotional support to the client.
  6. Assist with the specimen draw; prepare a heparinized syringe (if not already packaged). After obtaining a specimen, prevent any air from entering the syringe, because it may alter the blood gas analysis.
  7. Apply pressure immediately to the puncture site following the blood draw; maintain pressure for 5 minutes or for 10 minutes if the client is taking an anticoagulant to decrease the risk of hematoma. Reassess the radial pulse after removing the pressure.
  8. Appropriately label the specimen and transport it on ice to the laboratory.
  9. On the laboratory form, record the client’s temperature and the type of supplemental oxygen that the client is receiving.

Allen’s Test

Explain the Allen’s test to the client, including its purpose of assessing collateral circulation.

  1. Pressure is applied over the ulnar and radial arteries simultaneously.
  2. The client is asked to open and close the hands repeatedly.
  3. Pressure is released from the ulnar artery while compressing the radial artery.
  4. The color of the extremity distal to the pressure point is assessed. If flow through the ulnar artery is good, flushing will be seen immediately. The Allen test is then positive, and the radial artery can be used for puncture.
  5. If the test is negative (no flushing seen), the test is repeated on the other arm. If both arms are negative, another artery is selected for puncture.
  6. Findings are documented.

Arterial Blood Gas Analysis

Laboratory TestNormal RangeNormal Range (SI)
Arterial pH7.35 to 7.457.35 to 7.45
PaCO235 to 45 mm Hg35 to 45 mm Hg
Bicarbonate21 to 28 mEq/L21 to 28 mmol/L
PaO280 to 100 mm Hg80 to 100 mm Hg
Venous pH7.31 to 7.417.31 to 7.41
PvO240 to 50 mm Hg40 to 50 mm Hg

WARNING

The indicator for respiratory function is PaCO2. The indicator for metabolic function is HCO3-. The following steps do not consider a mixed imbalance, where both indicators correspond with the findings for respiratory and metabolic types. PaO2 is usually normal, except for with accompanying conditions and respiratory acidosis, where it is usually decreased.

  1. pH: is it increased (alkalosis) or decreased (acidosis)?
  2. PaCO2: if it has an opposite relationship with pH, it is a respiratory imbalance (high CO2 lowers pH, while low CO2 increases pH). If it does not, move to step 3.
  3. HCO3-: if it corresponds with pH, the condition is a metabolic imbalance.
  4. Compensation:
    • If pH is within normal ranges (7.35 to 7.45), full compensation has occurred. Acidosis or alkalosis depend on where the pH leans towards, despite being in the normal range.
    • If pH and both indicators are abnormal, partial compensation has occurred.
    • If pH is abnormal and only one of the indicators are abnormal, no compensation has occurred.

Respiratory Acid-Base Imbalance

Remember that the indicator for respiratory function is PaCO2. In a respiratory imbalance, you will find an opposite relationship between the pH and the PaCO2 i.e., elevated PaCO2 results in decreased pH (respiratory acidosis), and decreased PaCO2 results in elevated pH (respiratory alkalosis).

Respiratory acidosispHHCO3-PaCO2K+
Fully CompensatedNormalIncreasedIncreasedIncreased
Partially CompensatedDecreasedIncreasedIncreasedIncreased
UncompensatedDecreasedNormalIncreasedIncreased
Respiratory alkalosispHHCO3-PaCO2K+
Fully CompensatedNormalDecreasedDecreasedDecreased
Partially CompensatedIncreasedDecreasedDecreasedDecreased
UncompensatedIncreasedNormalDecreasedDecreased

Metabolic Acid-Base Imbalance

Remember that the indicator for respiratory function is HCO3-. In a respiratory imbalance, you will find a corresponding relationship between the pH and the HCO3- i.e., decreased HCO3- results in decreased pH (metabolic acidosis), and elevated HCO3- results in increased pH (metabolic alkalosis).

Metabolic acidosispHHCO3-PaCO2K+
Fully CompensatedNormalDecreasedDecreasedIncreased
Partially CompensatedDecreasedDecreasedDecreasedIncreased
UncompensatedDecreasedDecreasedNormalIncreased
Metabolic alkalosispHHCO3-PaCO2K+
Fully CompensatedNormalIncreasedIncreasedDecreased
Partially CompensatedIncreasedIncreasedIncreasedDecreased
UncompensatedIncreasedIncreasedNormalDecreased

Mixed Acid-Base Disorders

These occur when two or more disorders are present at the same time. The pH will depend on the type and severity of the disorders involved, including any compensatory mechanisms at work (e.g., respiratory acidosis combined with metabolic acidosis will result in a greater decrease in pH than either imbalance occurring alone).

  • Example: Mixed alkalosis can occur if a client begins to hyperventilate due to postoperative pain (respiratory alkalosis) and is also losing acid due to gastric suctioning (metabolic alkalosis).
  • These imbalances will feature both the inversion of PaCO2 and the correspondence of HCO3- to the pH imbalance.

Practice Questions

  1. The nurse reviews the arterial blood gas results of a client and notes the following: pH 7.45, PaCO2 of 30 mm Hg, and HCO3- of 20 mEq/L (mmol/L). The nurse analyzes these results as indicating which condition?
    • Metabolic acidosis, compensated
    • Respiratory alkalosis, compensated
    • Metabolic alkalosis, uncompensated
    • Respiratory acidosis, uncompensated
  1. The nurse is caring for a client with a nasogastric tube that is attached to low suction. The nurse monitors the client for manifestations of which disorder that the client is at risk for?
    • Metabolic acidosis
    • Metabolic alkalosis
    • Respiratory acidosis
    • Respiratory alkalosis
  1. A client with a 3-day history of nausea and vomiting and suspected of gastroenteritis presents to the emergency department. The client is hypoventilating and has a respiratory rate of 10 breaths per minute. The electrocardiogram (ECG) monitor displays tachycardia, with a heart rate of 120 beats per minute. Arterial blood gases are drawn, and the nurse reviews the results, expecting to note which finding?
    • A decreased pH and an increased PaCO2
    • An increased pH and a decreased PaCO2
    • A decreased pH and a decreased HCO3-
    • An increased pH and an increased HCO3-
  1. The nurse is caring for a client having respiratory distress related to an anxiety attack. Recent arterial blood gas (ABG) values are pH = 7.53, PaO2 = 72 mm Hg, PaCO2 = 32 mm Hg, and HCO3- = 28 mEq/L (28 mmol/L). Which conclusion would the nurse make?
    • The client has acidotic blood.
    • The client is probably overreacting.
    • The client is fluid volume overloaded.
    • The client is probably hyperventilating.
  1. The nurse is caring for a client with diabetic ketoacidosis and documents that the client is experiencing Kussmaul’s respirations. Which patterns did the nurse observe? Select all that apply.
    • Respirations that are shallow
    • Respirations that are increased in rate
    • Respirations that are abnormally slow
    • Respirations that are abnormally deep
    • Respirations that cease for several seconds
  1. A client who is found unresponsible has arterial blood gases drawn, and the results indicate the following: pH is 7.12, PaCO2 is 90 mm Hg, and HCO3- is 22 mEq/L (22 mmol/L). The nurse interprets the results as indicating which condition?
    • Metabolic acidosis with compensation
    • Respiratory acidosis with compensation
    • Metabolic acidosis without compensation
    • Respiratory acidosis without compensation
  1. The nurse notes that a client’s arterial blood gas (ABG) results reveal a pH of 7.50 and a PaCO2 of 30 mm Hg. The nurse monitors the client for which clinical manifestation associated with these ABG results?
    • Nausea
    • Confusion
    • Bradypnea
    • Tachycardia
    • Hyperkalemia
    • Light-headedness
  1. The nurse reviews the blood gas results of a client with atelectasis. The nurse analyzes the results and determines that the client is experiencing respiratory acidosis. Which result validates the nurse’s findings?
    • pH 7.25, PaCO2 50 mm Hg
    • pH 7.35, PaCO2 40 mm Hg
    • pH 7.50, PaCO2 52 mm Hg
    • pH 7.52, PaCO2 28 mm Hg
  1. The nurse is caring for a client who is on a mechanical ventilator. Blood gas results indicate a pH of 7.50 and a PaCO2 of 30 mm Hg. The nurse has determined that the client is experiencing respiratory alkalosis. Which laboratory value would most likely be noted in this condition?
    • Magnesium level of 1.8 (0.74 mmol/L)
    • Sodium level of 145 mEq/L (145 mmol/L)
    • Potassium level of 3.0 mEq/L (3.0 mmol/L)
    • Phosphorus level of 3.0 mg/dL (0.97 mmol/L)
  1. The nurse is caring for a client with several broken ribs. The client is most likely to experience what type of acid-base imbalance?
    • Respiratory acidosis from inadequate ventilation
    • Respiratory alkalosis from anxiety and hyperventilation
    • Metabolic acidosis from calcium loss due to broken bones
    • Metabolic alkalosis from taking analgesics containing base products

X: Vital Signs & Laboratory Reference Intervals

Vital signs include temperature, pulse, respirations, blood pressure (BP), oxygen saturation (pulse oximetry), and pain assessment. Initial measurement of vital signs provide baseline data on a client’s health status and is used to help identify changes in the client’s health status. The nurse collaborates with the primary health care provider (PHCP) in determining the frequency of vital sign assessment and also makes independent decisions regarding their frequency based on the client’s status.

  • Some vital sign measurements (temperature, pulse, respirations, BP, pulse oximetry) may be delegated to assistive personnel, but the nurse is responsible to interpreting the findings.

Documentation and Reporting

The nurse makes sure that vital sign measurements are documented correctly and reports abnormal, unexpected findings to the PHCP.

Vital signs are taken upon:

  1. Initial contact with a client (e.g. at admission, clinic visits, or home care visits)
  2. During physical assessment
  3. Before and after an invasive diagnostic or surgical procedure
  4. During the administration of medication that affects cardiac, respiratory, or temperature controlling functions. This may be required before, during, and after administration.
  5. Before, during, and after a blood transfusion.
  6. When the client’s condition changes or the client verbalizes unusual feelings, such as of nonspecific symptoms of physical distress (e.g., “I feel funny”).
  7. Whenever an intervention may affect a client’s condition, such as ambulation.
  8. When a fever or known infection is present (check q2° or q4°).

Temperature

Normal body temperature varies between literature. According to WebMD (2020), this range can fall between 97.0°F (36.1°C) to 99.0°F (37.2°C).

  • A fever can be defined as having an elevated temperature, feeling warm to touch, reporting feeling feverish, having a flushed face, glassy eyes, or chills. Some health care providers consider a client as febrile if their temperature is at or higher than 100.4°F (38°C). Follow agency guidelines and provider preferences regarding temperature.
  • Common sites for measurement include the mouth, rectum (unless contraindicated), axilla, ear, and across the forehead (temporal artery site).
    • Rectal temperatures are often 1°F (0.5°C) higher than the oral temperature.
    • Tympanic and axillary temperatures are about 1°F (0.5°C) lower than the oral temperature.

Temperature Conversion

F to C: C to F: Example:

Nursing Considerations

  1. Time of Day: temperatures is lower in the normal range when awakening (from inactivity), and peaks in the late afternoon or evening by as much as 1 to 2 degrees, as a result of environmental temperature, metabolic processes, and activity.
  2. Environmental Temperature: cold weather and warm weather affects normal body temperature ranges.
  3. Age: temperature fluctuates in infants as they have poor thermoregulation. Older adults also lose subcutaneous fat, have slower metabolism, and are less active, which reduce their ability to maintain body temperature.
  4. Physical Exercise: using large muscles generate heat, warming up the body.
  5. Menstrual Cycle: the basal body temperature of women may decrease by 1°F just before ovulation, then increase by 1°F during ovulation.
  6. Pregnancy: increased metabolism may consistently elevate temperatures to the higher normal ranges.
  7. Stress: emotions increase hormonal secretion, increasing heat production and temperature.
  8. Illness: infective agents and the inflammatory response may cause an increase in temperature.
  9. Not being able to obtain a temperature may indicate hypothermia, a life-threatening condition in very young and older clients.

Methods of Measurement

  1. Oral: the thermometer is placed under the tongue in one of the posterior sublingual pockets; ask the client to keep the tongue down and the lips closed and not to bite down on the thermometer.
    • The nurse must wait 15 to 30 minutes after the patient has consumed hot or cold foods and liquids, chewed gum, or smoked before taking temperature orally.
  2. Rectal: used if temperature cannot be obtained orally or via other methods, such as when the patient has nasal congestion, has undergone nasal or oral surgery, or had the jaws wired, has a nasogastric tube in place, is unable to keep the mouth closed, or is at risk for seizures. The patient is placed in a side-lying position. The thermometer is lubricated and inserted into the rectum, toward the umbilicus, by about 1.5 inches (3.8 cm; no more than 0.5 inches [1.25 cm] in infants).
    • This method is contraindicated in cardiac patients; clients who underwent rectal surgery; clients with diarrhea, fecal impaction, or rectal bleeding; or who is at risk for bleeding.
  3. Axillary: used if oral or other methods of temperature measurement are contraindicated. It is less accurate than the oral, rectal, tympanic, or temporal artery methods, but is used when other methods are not possible. The thermometer is placed in the client’s dry axilla, and the client is asked to hold the arm tightly against the chest, resting the arm on the chest.
    • Different manufacturers provide different durations for how long the thermometers should stay in the axilla. Some beep once measurement is done.
  4. Tympanic: only used if the client does not have an inflammatory condition of the auditory canal, or if discharge from the ear is present. The reading may be affected by an ear infection or excessive wax blocking the ear canal.
    • Check the auditory canal for redness, swelling, discharge, or a foreign body before inserting the probe.
  5. Temporal Artery: ensure that the client’s forehead is dry. The probe is placed flush against the skin, and slid across the forehead or placed in the area of the temporal artery and held in place. If the client is diaphoretic, the probe may be placed on the client’s neck, just behind the earlobe.

Pulse

A pulse is a palpable bounding of blood flow in a peripheral artery; it is an indirect indicator of circulatory status. The average adult pulse (heart) rate is 60 to 100 beats per minute (BPM), but may be lower in well-conditioned athletes.

  • Changes in pulse rate are used to evaluate the client’s tolerance of interventions such as ambulation, bathing, dressing, and exercise.
  • Pedal pulses are checked to determine whether the circulation is blocked in the artery up to that pulse point. If difficult to locate, a Doppler ultrasound stethoscope (ultrasonic stethoscope) may be needed to amplify the sounds of pulse waves.

Pulse qualities include rate (frequency), rhythm (pattern), strength (force or amplitude), and equality. Use these qualities in determining the grading scale for pulses:

GradingQuality
4+Strong and bounding
3+Full pulse, increased
2+Normal, barely palpable
1+Weak, barely palpable
They can be found at the following points:
  1. Temporal Artery: anterior to or in the front of the ear.
  2. Carotic Artery: in the groove between the trachea and the sternocleidomastoid muscle, medial to and alongside the muscle.
  3. Apical Pulse: at the left midclavicular line, along the fifth intercostal space.
  4. Brachial Pulse: just above the elbow at the antecubital fossa, between the biceps and triceps muscles.
  5. Radial Pulse: along the groove along the radial or thumb side of the client’s inner wrist.
  6. Ulnar Pulse: located in the medial side of the wrist.
  7. Femoral Pulse: below the inguinal ligament, midway between the symphysis pubis and the anterosuperior iliac spine.
  8. Popliteal Pulse: located behind the knee
  9. Posterior Tibial Pulse: located in the inner side of the ankle, behind and below the medial malleolus (ankle bone).
  10. Dorsalis Pedis Pulse: on top of the foot, in line with the groove between the extensor tendons of the great and first toes.

Nursing Considerations

  1. Age: normal heart rate goes down as an individual ages.
  2. Exercise increases heart rate.
  3. Emotions stimulate the sympathetic nervous system, increasing the heart rate.
  4. Pain increases heart rate.
  5. Increased body temperature causes the heart rate to increase.
  6. Stimulant medications increases the heart rate; depressants and medications affecting the cardiac system slow it.
  7. Lowering blood pressure or circulation volume (e.g. hemorrhaging) often increases heart rate.

Pulse Deficit

A condition where the peripheral pulse rate (radial pulse) is less than the ventricular contraction rate (apical pulse). This indicates a lack of peripheral perfusion; it can be an indication of cardiac dysrhythmias. A deficit indicates that cardiac contractions are ineffective, failing to send pulse waves to the periphery. If a difference is noted, the PHCP is notified.

  • One-examiner Technique: auscultate and count the apical pulse, then immediately count the radial pulse.
  • Two-examiner Technique: each examiner simultaneously auscultates each of the pulses.

Respirations

Respiration is a mechanism the body uses to exchange gases between the atmosphere and the blood and between the blood and the cells. These may vary with age. The normal adult respiratory rate is 12 to 20 breaths per minute.

  • Count the client’s respirations after measuring the radial pulse. Keep holding the client’s wrist while counting the respirations, or position the hand on the client’s chest. You may count the respirations for just 30 seconds then multiply by 2, except in clients known to be very ill or exhibiting irregular respirations.
  • One count of respiration includes both inspiration and expiration. The rate, depth, pattern, and sounds are assessed.

Nursing Considerations

Many of the factors that affect the [[#Pulse#Nursing Considerations]] also affect respiratory rate.

  • An increased level of carbon dioxide or a lower level of oxygen in the blood results in an increase in respiratory rate.
  • Head injury or increased intracranial pressure will depress the respiratory center (medulla oblongata), resulting in shallow respirations or slowed breathing.
  • Medications such as opioid analgesics depress respirations.
  • Additional factors such as exercise, pain, anxiety, smoking, and body positioning can also affect respiratory rate.

Blood Pressure

Blood pressure is the force on the walls of an artery exerted by the pulsating blood under pressure from the heart. The heart’s contraction forces blood under high pressure into the aorta; the peak of maximum pressure during ejection is the systolic pressure; the blood remaining in the arteries when the ventricles relax exerts a force known as the diastolic pressure.

  • The difference between the systolic and diastolic pressure is called the pulse pressure.
  • Normal systolic pressure for adults should be below 120 mm Hg, and a diastolic pressure under 80 mm Hg.
  • If two or more readings on at least two subsequent health care visits are greater than 120/80 mm Hg, hypertension may be diagnosed.
  • In postural hypotension, a normotensive client exhibits symptoms and low BP upon rising to an upright position. To obtain vital sign measurements for these clients, check the BP and pulse with the client supine, sitting, and standing. Take 1 to 3 minutes in between each change in position before obtaining vital signs.

Nursing Considerations

  1. Blood pressure tends to increase with age.
  2. Stress produces sympathetic stimulation, increasing blood pressure.
  3. Black and East Asian populations have a higher incidence of high blood pressure.
  4. Antihypertensive medications and opioid analgesics can decrease blood pressure.
  5. Blood pressure is typically lowest in the early morning, increasing gradually throughout the day, peaking in the late afternoon and evening.
  6. Additional factors affecting the blood pressure include smoking, activity, and body weight.

Guidelines for measuring blood pressure:

  • Determine the best site for assessment. Avoid applying a cuff to an extremity into which intravenous fluids are infusing, where an arteriovenous shunt or fistula is present, on the side on which breast or axillary surgery has been performed, or on an extremity that has been traumatized or is deceased.
  • The leg may be used if the brachial artery is inaccessible; the cuff is wrapped around the thigh and the stethoscope is placed over the popliteal artery.
  • Ensure that the client has not smoked or exercised within 30 minutes, because both can yield falsely high readings. Have the client assume a sitting (with feet flat on floor) or lying position and then rest for 5 minutes before the measurement; ask the client not to speak during the measurement.
  • Ensure that the cuff is fully deflated, and then wrap it evenly and snugly around the extremity. It should be the right size, as cuffs that are too small produce a falsely high reading, and a cuff that is too large will yield a falsely low one.
  • Ensure that the stethoscope being used fits the examiner and does not impair hearing.
  • Document the first Korotkoff sound at phase 1 (heard as the blood pulsates through the vessel when air is released from the BP cuff and pressure on the artery is reduced) as the systolic pressure, and the beginning of the fifth Korotkoff sound at phase 5 as the diastolic pressure.
  • Blood pressure readings obtained electronically with a vital sign monitoring machine should be checked with a manual cuff if there is any concern with the accuracy of the reading.

Hypertension

American College of Cardiology, 2017

  • Normal: less than 120/80 mm Hg
  • Elevated: 120 - 129/<80 mm Hg
  • Stage 1: 130 - 139/80 - 89 mm Hg
  • Stage 2: ≥140/≥90 mm Hg
  • Hypertensive Crisis: >180/>120 mm Hg (at least one) that produces an immediate need for a change in medication (if not contraindicated) or hospitalization if there are signs of organ damage.

Ensure the use of proper technique to measure blood pressure. Teach clients the use of home blood pressure monitoring using validated devices.

  • Health care providers should be able to reveal white-coat hypertension.
  • Prescribe medication for stage I hypertension if a client has already had a cardiovascular event such as a heart attack or stroke, or is at high risk for them based on age, diabetes mellitus, chronic kidney disease, or calculation of atherosclerotic risk.
  • Recognize that many people will need two or more types of medication, and that adherence may improve if multiple medications are combined into a single pill.
  • Identify socioeconomic status and psychosocial stress as risk factors for high blood pressure that should be considered in the patient’s plan of care.

Pulse Oximetry

Pulse oximetry is a noninvasive test that registers the oxygen saturation of the client’s hemoglobin. The capillary oxygen saturation (SaO2) is recorded as a percentage. Its normal value is from 95% to 100%. The arterial oxygen pressure (PaO2) is used during hypoxia. When these stores run out, the oxygen bound to hemoglobin (SaO2) is drawn on to provide oxygen to the tissues. A sensor is placed on the client’s finger, toe, nose, earlobe, or forehead to measure oxygen saturation, which is then displayed on a monitor.

  • Pulse oximetry can alert the nurse to hypoxemia before clinical signs appear.
  • If readings are below normal, instruct the client in deep-breathing techniques and recheck the pulse oximetry.

Nursing Considerations

A vascular, pulsatile area, such as the fingertip or earlobe is needed to detect the degree of change in the transmitted light that measures the oxygenated and deoxygenated hemoglobin.

  • Factors that affect light transmission (movement, fingernail polish, ambient light, hypotension, anemia, peripheral vascular disorders) also affect the measurement of SpO2.
  • Do not select an extremity with an impediment to blood flow or that is cold in temperature.
  • Any reading below 90% should alert the PHCP. This level is only acceptable in certain chronic conditions. Agency procedures and PHCP prescriptions are followed according to specific readings.

Pain

There are various types of pain:

  1. Acute/transient pain, usually associated with an injury, condition, or procedure that lasts from hours to days.
  2. Chronic/persistent noncancer pain, usually associated with long-term or chronic illnesses or disorders that lasts from months to years.
  3. Chronic/episodic pain, occurring sporadically over an extended period of time. Episodes last for hours, days, or weeks.
  4. Cancer pain, affecting many but not all cancer patients, appear as acute or chronic pain, often caused by tumor progression and related pathological processes, invasive procedures, treatment toxicities, infection, and physical limitations.
  5. Idiopathic pain, chronic pain that appears in the absence of an identifiable physical or psychological cause or pain perceived as excessive for the extent of an organic pathological condition.

Assessment

Pain is a highly subjective experience. Ask the client to describe pain in terms of timing, location, severity, quality, aggravating and precipitating factors, and relief measures.

  • Ask the patient about complementary and alternative therapies they use for pain.
  • Older clients may experience pain differently from other age groups, e.g., sleep disturbances, changes in gait and mobility, decreased socialization, depression)
  • Clients with cognitive disorders may have difficulty in describing their pain.
  • The nurse should be alert for nonverbal indicators for pain: moaning, crying, irritability, restlessness, grimacing or frowning, inability to sleep, rigid posture, increased blood pressure, heart rate, or respiratory rate, nausea, diaphoresis
    • Use the FLACC® (face, legs, arms, cry, consolability) scale or FACES® pain scale for children or clients who cannot communicate verbally.
  • The client can be asked to use a number-based, description-based, or picture-based pain scale to rate the degree of pain.
  • Evaluate the client’s response to nonpharmacological interventions.

Conventional Nonpharmacological Interventions

  1. Cutaneous Stimulation: techniques involving the application of heat, cold, pressure, and vibration. Therapeutic touch and massages are also under this, and may be considered complementary and alternative techniques. Such interventions may require a PHCP’s prescription.
  2. Transcutaneous Electrical Nerve Stimulation (TENS), AKA Percutaneous ENS (PENS), involves the application of a battery-operated device that delivers a low electrical current to the skin and underlying tissues to block pain. This may require a prescription, but some units do not require one.
  3. Binders, Slings, and other Supportive Devices: cloths or other materials or devices, wrapped around a limb or body part, can ease the pain of strains, sprains, and surgical incisions. Some of these may require a PHCP’s prescription. Elevation of the affected body part is another intervention that can reduce swelling; supporting an extremity on a pillow may lessen discomfort.
  4. Heat and Cold Therapy: the application of heat and cold or alternating application of the two can soothe pain resulting from a muscle strain; cold reduces swelling. In some conditions, this may require a PHCP’s prescription or may be contraindicated.
    • Heat application utilizes warm-water compresses, warm blankets, thermal pads, and tub and whirlpool baths. Temperature must be monitored carefully to avoid burns, particularly for very young or old clients. The clients should be advised to remove the source of heat or cold if changes in sensation or discomfort occur. If, after removal, the change in sensation or discomfort is not relieved, inform the PHCP.
    • Heat or cold should not be applied directly to the skin; use a towel or other barrier. They should not be left in place for more than 15 to 30 minutes.

Complementary and Alternative Therapies

These are used in addition to conventional treatment to provide healing resources and focus on the mind-body connection.

  • Acupuncture and acupressure
  • Biofeedback
  • Chiropractic manipulation, Massage, Therapeutic Touch
  • Distraction, Guided imagery, Meditation, Relaxation, Breathing, and Repositioning techniques
  • Herbal therapies
  • Hypnosis
  • Laughter and humor
  • Art and music therapy
  • Spiritual Measures (Prayer, using a rosary or prayer beads, reading scripture)

Herbal therapies may be considered as pharmacologic therapy by some PHCPs. They may pose a risk for interacting with prescription medications, and as such their use should be identified by the nurse.

If cultural or spiritual measures are to be employed, the nurse must elicit from the client the preferred forms of spiritual expression and learn when they are practiced as to integrate them into the plan of care.

Pharmacological Interventions

Non-opioid Analgesics

  1. Nonsteroidal antiinflammatory drugs (NSAIDs) and Acetylsalicylic acid (Aspirin): these are contraindicated if the client has gastric irritation, ulcer disease, or an allergy to the medication. Bleeding is a concern with these medication types.
    • Instruct the client to take oral doses with milk or a snack to reduce gastric irritation.
    • NSAIDs can amplify the effects of anticoagulants.
    • Hypoglycemia may result if both ibuprofen and oral antidiabetic agent are being taken.
    • A high risk of toxicity exists if both ibuprofen and a calcium channel blocker are being taken.
    • Side and Adverse Effects:
      • NSAIDs: gastric irritation, sodium and water retention, bloody dyscrasias, tinnitus, pruritus
      • Acetylsalicylic Acid: gastric irritation, flushing, tinnitus
  2. Acetaminophen: commonly known as Tylenol, is contraindicated in patients with hepatic or renal disease, alcoholism, or hypersensitivity.
    • Assess the client for liver dysfunction.
    • Monitor for signs of hepatic damage (e.g., nausea and vomiting, diarrhea, abdominal pain, jaundice) and monitor liver function parameters.
    • Tell the patient that self-medication should not continue longer than 10 days in an adult or 5 days in a child because of the risk of hepatotoxicity.
    • The antidote to acetaminophen is acetylcysteine.

The major concern for acetaminophen is hepatotoxicity.

Opioid Analgesics

Opioid analgesics suppress pain impulses, but can also suppress respiration and coughing by acting on the respiratory and cough center located in the medulla of the brainstem.

  • Review the client’s history, and note that clients with impaired renal or liver function may only be able to tolerate low doses. Also assess for allergy.
  • IV routes are faster, but last shorter. An electronic infusion device is always used for continuous or dose-demand IV infusion of opioid analgesics.
  • Some opioids produce euphoria and sedation. Long-term use may cause physical dependence.
  • Administer medication 30 to 60 minutes before painful activities, such as coughing and deep breathing, ambulation, and dressing changes.
  • Monitor the respiratory rate. If bradypnea develops, withhold the medication and inform the PHCP.
  • Monitor the pulse. If bradycardia develops, withhold the medication and notify the PHCP.
  • Check for hypotension prior to administration to decrease the risk for adverse effects.
  • Auscultate the lungs for normal breath sounds.
  • Encourage activities such as turning, deep breathing, and incentive spirometry to prevent atelectasis and pneumonia.
  • Monitor the client’s level of consciousness.
  • Initiate safety precautions.
  • Monitor intake and output and assess the client for urine retention and constipation. The latter is common in opioid use.
  • Instruct the client to take oral doses with milk or a snack to reduce gastric irritation.
  • Instruct the client to avoid activities that require alertness while on the medication, such as operating machinery or driving.
  • Assess the effectiveness of the medication 30 minutes after administration.
  • Have an opioid antagonist (e.g., naloxone), oxygen, and resuscitation equipment available.
  • Prescriptions for opioid analgesics are only given under specific circumstances. Forms for their use, including risk assessment tools and informed consent forms are required. Prescription monitoring is necessary to avoid multiple prescriptions for the same medication.
  • A pain management specialist needs to be consulted for complex pain management cases.

Adjuvant Analgesics

These medications complement the effects of opioid analgesics. They are especially helpful for neuropathic pain. These were originally developed for other conditions, such as depression, seizures, or dysrhythmias.

  • Amitriptyline, venlafaxine, gabapentin
  • Marijuana and other substances such as CBD may be considered for use for pain management, depending on physician preference and its legal status for use.

These medications vary in class, side effects, and considerations. Nursing interventions should be done accordingly.

MedicationSide and Adverse Effects
NSAIDsGastric irritation, sodium and water retention, blood dyscrasias, tinnitus, pruritus
Acetylsalicylic AcidGastric irritation, flushing, tinnitus
AcetaminophenHepatotoxicity
OpioidsPhysical dependence, addiction, respiratory depression, atelectasis, pneumonia, cough suppression, bradycardia, hypotension, urine retention, constipation, gastric irritation, euphoria, sedation

Laboratory Reference Intervals

Serum Sodium

Sodium (135 to 145 mEq/L, 135 to 145 mmol/L) is a major cation of extracellular fluid and serves to maintain osmotic pressure and acid-base balance, and assists in the transmission of nerve impulses.

  • Sodium is absorbed from the small intestine and excreted in the urine in amounts dependent on dietary intake.

Elevations (Hypernatremia) occur in dehydration, impaired renal function, increased dietary or IV intake of sodium, primary aldosteronism, and use of corticosteroid therapy.

Depressions (Hyponatremia) occur in Addison’s disease, decreased dietary intake of sodium, diabetic ketoacidosis, diuretic therapy, excessive loss from the gastrointestinal (GI) tract, excessive perspiration, and water intoxication.

Serum Potassium

Potassium (3.5 to 5.0 mEq/L, 3.5 to 5.0 mmol/L) is a major intracellular cation and serves to regulate cellular water balance, electrical conduction in muscle cells, and acid-base balance.

  • Potassium is obtained through dietary ingestion, and the kidneys preserve or excrete potassium depending on cellular need.
  • Potassium levels are used to evaluate cardiac function, gastrointestinal function, and the need for IV replacement therapy.
  • If the client is receiving potassium supplements, this should be noted on the laboratory form.

Elevations (Hyperkalemia) occur in acute or chronic kidney disease, Addison’s disease, dehydration, diabetic ketoacidosis, excessive dietary or IV intake of potassium, massive tissue destruction, and metabolic acidosis.

  • Falsely high readings may be found in clients with elevated white blood cells and platelet cells.

Depressions (Hypokalemia) occur in burns, Cushing’s syndrome, deficient dietary intake of potassium, severe diarrhea, diuretic therapy, GI fistula, insulin administration, pyloric obstruction, starvation, and vomiting.

Activated Partial Thromboplastin Time

aPTT (30 to 40 seconds, depending on type of activator used) evaluates how well the coagulation sequence (intrinsic clotting system) is functioning by measuring the amount of time it takes in seconds for recalcified citrated plasma to clot after partial thromboplastin is added to it. It screens for deficiencies and inhibitors of all factors except VII and XIII.

  • This is usually used to monitor the effectivity of heparin therapy and screen for coagulation disorders.
  • If the client is receiving intermittent heparin therapy, blood samples should be drawn 1 hour before the next scheduled dose. These should not be drawn from the arm into which heparin is infusing.
  • Specimen should be transported to the laboratory immediately.
  • Provide direct pressure to the venipuncture site for 3 to 5 minutes.
  • If the patient is receiving heparin therapy, the aPTT results should return 1.5 to 2.5 times normal.

Elevations occur in deficiency of one or more of the following: factor I, II, V, or VIII; factors IX and X; factor XI; and factor XII; hemophilia; heparin therapy; liver disease

Bleeding Precautions

If the aPTT value is prolonged (longer than 100 seconds or per agency policy) in a client receiving IV heparin therapy or in any client at risk for thrombocytopenia, initiate bleeding precautions.

Prothrombin Time (PT) and International Normalized Ratio (INR)

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