UNIT 6 (HOMEOSTASIS)

Chapter 44: Fluid Imbalances

Maintained by balance of volume, osmolality, electrolytes, and pH

Body fluid content

• Adults: 55%–60% of body weight

• Older adults: ~50%–55% (decreased muscle mass, ↓ thirst)

Fluid movement between compartments via

• Diffusion

• Osmosis

• Filtration

• Active transport

Fluid balance regulated by intake vs output

• Intake influenced by thirst, habits, social factors

• Output via kidneys (primary regulator), skin, lungs, GI tract

Types of Fluid Imbalances

• Volume imbalances

  • Too little or too much isotonic fluid

• Osmolality imbalances

  • Hypertonic or hypotonic states

  • Examples

    • Hypernatremia (water deficit)

    • Hyponatremia (water excess or intoxication)

Body Fluid Compartments

Intracellular Fluid (ICF)

• Two-thirds of total body water

• Fluid inside cells

Extracellular Fluid (ECF)

• One-third of total body water

• Fluid outside cells

• Subdivisions

  • Intravascular: plasma (liquid part of blood)

  • Interstitial: between cells and blood vessels

  • Transcellular: epithelial secretions

    • CSF

    • Pleural

    • Peritoneal

    • Synovial

Intracellular / Extracellular / Plasma (image)

Dehydration

Deficit of body fluid from inadequate intake or excessive loss

Types

• Actual dehydration

  • Total body water loss

• Relative dehydration

  • Fluid shifts from intravascular to interstitial space

• Hypovolemia (isotonic dehydration)

  • Loss of water and electrolytes

  • ↓ circulating blood volume

  • Also called fluid volume deficit

Dehydration Risk Factors

Causes of Isotonic Fluid Volume Deficit (Hypovolemia)

• GI losses

  • Vomiting

  • Diarrhea

  • NG suctioning

• Skin losses

  • Diaphoresis without fluid replacement

• Renal losses

  • Diuretics

  • Kidney disease

  • Adrenal insufficiency

• Third spacing

  • Burns

• Blood or plasma loss

  • Hemorrhage

• Decreased intake

  • Anorexia

  • Nausea

  • Impaired swallowing

  • Confusion

  • NPO status

Causes of Dehydration

• Hyperventilation or excessive perspiration without fluids

• Prolonged fever

• Diabetic ketoacidosis

• Inadequate water intake

  • Enteral feedings without free water

  • ↓ thirst sensation

  • Aphasia

• Diabetes insipidus

• Osmotic diuresis

• Excessive sodium intake

  • Salt tablets

  • Hypertonic IV fluids

Dehydration Findings

Vital Signs

• Tachycardia (compensatory)

• Hypotension

• Orthostatic hypotension

• Thready pulse

• ↓ central venous pressure

• Tachypnea (compensation)

• Hypothermia

Neuromusculoskeletal

• Dizziness

• Syncope

• Confusion

• Weakness

• Fatigue

Gastrointestinal

• Thirst

• Dry, furrowed tongue

• Nausea

• Vomiting

• Anorexia

• Acute weight loss

Renal

• Oliguria (↓ urine output and concentration)

Other Findings

• Delayed capillary refill

• Cool, clammy skin

• Diaphoresis

• Sunken eyeballs

• Flattened neck veins

• Poor skin turgor, tenting

• Weight loss

• ↓ CVP

• Older adults at higher risk due to

  • ↓ skin elasticity

  • ↓ GFR and urine-concentrating ability

  • ↓ muscle mass

  • ↓ thirst reflex

• Severe dehydration

  • Elevated temperature

  • Risk of seizures

Dehydration Labs

Hematocrit: ↑ in hypovolemia

BUN: ↑ (>25 mg/dL) from hemoconcentration

Urine specific gravity: >1.030

Serum sodium: >145 mEq/L (with dehydration)

Serum osmolality: >295 mOsm/kg (dehydration, hypernatremia)

Note

• With hemorrhage, hemoconcentration does not occur initially

Dehydration Care

Administer oral or IV rehydration

Monitor I&O

Monitor vital signs

• Orthostatic BP

• Heart rate

Monitor mental status (early sign of worsening imbalance)

Weigh every 8 hours during fluid replacement

Assess gait stability

• Use call light

• Assist with ambulation (fall risk)

Instruct slow position changes

Interprofessional Care

• Collaborate on

  • Fluid replacement strategy

  • Oxygen management

Client Education

• Encourage adequate fluid intake

• Identify dehydration causes

  • Vomiting

  • Diarrhea

  • Large draining wounds

  • Excessive ostomy output

Dehydration Complications

Hypovolemic Shock

• Results from severe fluid loss

• ↓ MAP → ↓ tissue perfusion

• ↓ oxygen delivery to cells

Nursing Actions

• Administer oxygen

  • O₂ saturation <70% = emergency

• Remain with unstable client

• Monitor vital signs every 15 minutes

• Fluid replacement

  • Colloids

    • Whole blood

    • Packed RBCs

    • Plasma

    • Synthetic plasma expanders

  • Crystalloids

    • Normal saline

    • Lactated Ringer’s

• Administer medications as ordered

  • Vasoconstrictors

    • Dopamine

    • Norepinephrine

    • Phenylephrine

  • Inotropes

    • Dobutamine

    • Milrinone

  • Vasodilators for perfusion support

    • Sodium nitroprusside

• Perform hemodynamic monitoring

The nurse is assessing the client who reports nausea, vomiting, and weakness. Which of the following findings nurse are manifestations of fluid volume deficit?

Select all that apply.

a

Potassium level

b

Urine specific gravity

c

Heart rate

d

Temperature

e

Oxygen saturation

b

Urine specific gravity

c

Heart rate

d

Temperature

Overhydration

Excess fluid in the body from excessive intake or ineffective removal

Key Concepts

• Fluid overload

  • Excess water or fluid

  • Includes water intoxication

  • Causes hemodilution (↓ blood components like cells and electrolytes)

• Hypervolemia

  • Excess water and electrolytes in correct proportions

  • Example: excessive sodium intake → water retention

• Increased risk for

  • Pulmonary edema

  • Congestive heart failure

• Older adults at higher risk due to

  • ↓ kidney function

  • Age-related regulatory changes

Health Promotion and Disease Prevention

• For clients with heart disease or kidney impairment

  • Consume low-sodium diet

  • Follow prescribed dietary restrictions

  • Restrict fluid intake as ordered

Overhydration Risk Factors

Causes of Hypervolemia

• Compromised regulatory systems

  • Heart failure

  • Kidney disease

  • Cirrhosis

• Excessive fluid administration

  • Oral

  • Enteral

  • IV

• Fluid shifts after burns

• Prolonged corticosteroid use

• Severe stress

• Hyperaldosteronism

Causes of Overhydration

• Water replacement without electrolytes

• Excessive water intake

  • Forced intake

  • Psychogenic polydipsia

• SIADH (syndrome of inappropriate antidiuretic hormone)

• Excessive IV fluids

• Hypotonic solutions used for irrigation

Overhydration Findings

Vital Signs

• Tachycardia

• Bounding pulse

• Hypertension

• Tachypnea

• ↑ central venous pressure

Neuromuscular

• Weakness

• Visual changes

• Paresthesias

• Altered level of consciousness

• Seizures (severe, rapid hyponatremia from water excess)

Gastrointestinal

• Ascites

• ↑ GI motility

• Hepatomegaly

Respiratory

• Crackles

• Cough

• Dyspnea

Other Findings

• Peripheral edema

• Pulmonary congestion

• Weight gain

• Distended neck veins

• ↑ urine output

• Skin warm, pale, taut

Overhydration Exams

Laboratory Findings

• ↓ Hematocrit and hemoglobin (hemodilution)

• ↓ Serum osmolality

• ↓ Urine sodium

• ↓ Urine specific gravity

• ↓ BUN (plasma dilution)

---

Diagnostic Procedures

• Chest X-ray

  • Possible pulmonary congestion

Overhydration Care

Monitor intake and output

Monitor daily weight

• 1 kg (2.2 lb) change in 24 hr = ~1 L fluid

Assess lung sounds

Monitor peripheral edema

Maintain sodium-restricted diet as prescribed

Maintain fluid restriction if ordered

Encourage rest

Monitor response to diuretics

Review OTC medications for sodium content

Positioning

• Semi-Fowler’s or Fowler’s

• Reposition regularly to prevent skin breakdown

Use pressure-reducing mattress

Assess bony prominences

Monitor serum sodium and potassium

Interprofessional Care

• Consult respiratory therapy for oxygen management

• Consult pulmonology if fluid shifts into lungs

Client Education

• Weigh daily

  • Report 1–2 lb gain in 24 hr

  • Report 3 lb gain in 1 week

• Follow low-sodium diet

  • Read food labels

  • Track daily sodium intake

• Adhere to fluid restrictions

  • Divide daily fluid allowance evenly over 24 hr

Overhydration Complications

Pulmonary Edema

• Caused by severe fluid overload

Manifestations

• Anxiety

• Tachycardia

• Distended neck and hand veins

• PVCs

• Dyspnea at rest

• Altered LOC

• Restlessness, lethargy

• Moist crackles

• Frothy, pink-tinged sputum

Nursing Actions

• Position in high-Fowler’s to improve ventilation

• Administer oxygen

• Prepare for positive airway pressure or intubation if needed

• Administer medications as prescribed if BP adequate

  • Morphine

  • Nitrates

  • Diuretics

Pitting edema (image)

A nurse is planning care for a client who has fluid volume excess. Which of the following interventions should the nurse include in the plan? 

Select all that apply.

a

Check the client’s weight 2 times per week

b

Place the client in a semi-Fowler’s position

c

Monitor the client’s breath sounds

d

Change the client’s position every 4 hrs

e

Assess the client for peripheral edema

Fluid volume deficit

Sunken eyeballs

Poor skin turgor

Fever

Fluid volume excess

Bounding pulse

Crackles heard in lung fields

Distended neck veins

A nurse is planning care for a client who has fluid volume excess. Which of the following interventions should the nurse include in the plan? 

Select all that apply.

a

Check the client’s weight 2 times per week

b

Place the client in a semi-Fowler’s position

c

Monitor the client’s breath sounds

d

Change the client’s position every 4 hrs

e

Assess the client for peripheral edema

b

Place the client in a semi-Fowler’s position

c

Monitor the client’s breath sounds

e

Assess the client for peripheral edema

Chapter 45: Electrolyte Imbalances

Electrolytes are charged ions dissolved in body fluids.

Cations are positively charged. Anions are negatively charged.

Electrolytes are distributed between intracellular fluid (ICF) and extracellular fluid (ECF).

Differences in electrolyte concentration between ICF and ECF maintain cell excitability and nerve impulse transmission.

Body fluids remain electrically neutral overall.

Electrolytes conduct electrical current.

Imbalances occur from altered intake or output.

Older adults and ill clients are at higher risk.

Serum labs reflect plasma levels only, not intracellular levels.

Common Electrolytes

• Cations: sodium, potassium, calcium, magnesium, hydrogen

• Anions: chloride, bicarbonate, phosphate, sulfate, proteins

Expected Reference Ranges

• Sodium: 136–145 mEq/L

• Potassium: 3.5–5.0 mEq/L

• Calcium: 9.0–10.5 mg/dL

• Magnesium: 1.3–2.1 mEq/L

• Chloride: 98–106 mEq/L

• Phosphorus: 3.0–4.5 mg/dL

Sodium Imbalances

Physiology

• Sodium (Na⁺) is the primary ECF cation.

• Regulates ECF osmolarity and fluid balance.

• ICF sodium is low (≈14 mEq/L).

• Sodium gradients are critical for muscle contraction, cardiac function, and nerve transmission.

• Water follows sodium concentration.

• Kidneys regulate sodium via aldosterone, ADH, and natriuretic peptides.

Hyponatremia

Serum sodium less than 136 mEq/L.

Caused by sodium loss or excess free water.

Pathophysiology

• Slowed membrane depolarization.

• Water shifts from ECF into ICF, causing cellular edema.

• Risk of cerebral edema.

Common Causes

• Fluid imbalance leading to sodium loss.

• Compensatory renal excretion of sodium-free water.

Diagnostic Clues

• Urine sodium helps distinguish renal vs nonrenal losses.

Hyponatremia Risk Factors

Actual Sodium Deficit

• Excessive sweating

• Diuretic use

• Wound drainage, especially GI

• NG tube suction of isotonic gastric contents

• Decreased aldosterone secretion

• Kidney disease

• Hyperlipidemia

• Inadequate sodium intake or NPO status

• Hyperglycemia

• Low-sodium diet

• Cerebral salt wasting syndrome

Relative Sodium Deficit Due to Dilution

• Excess hypotonic fluids (psychogenic polydipsia, forced intake, hypotonic irrigation)

• Freshwater submersion

• Kidney failure or nephrotic syndrome

• Heart failure

• SIADH

• Medications: SSRIs, desmopressin

• Older adult status with chronic illness and diuretic use

Hyponatremia Findings

General

• Manifestations depend on ECF volume status: euvolemic, hypovolemic, or hypervolemic.

Hypervolemic Hyponatremia

• Bounding pulse

• Blood pressure normal or elevated

Vital Signs in Hypovolemia

• Hypothermia

• Tachycardia

• Rapid, thready pulse

• Hypotension

• Orthostatic hypotension

• Diminished peripheral pulses

Neuromuscular

• Headache

• Confusion

• Lethargy

• Muscle weakness

• Fatigue

• Decreased deep tendon reflexes

• Dizziness or lightheadedness

• Seizures

• Possible respiratory compromise

Gastrointestinal

• Increased GI motility

• Hyperactive bowel sounds

• Abdominal cramping

• Nausea

Hyponatremia Exams

Serum sodium: less than 136 mEq/L

Serum osmolality: decreased

Urine sodium:

• Less than 20 mEq/L with sodium loss

• Greater than 20 mEq/L in SIADH

Urine specific gravity:

• Decreased (1.002–1.004) with sodium loss

• Increased in SIADH

Hyponatremia Care

Encourage oral sodium intake if tolerated.

Provide high-sodium foods and fluids such as broth or tomato juice.

Administer isotonic IV fluids such as 0.9% normal saline or lactated Ringer’s.

Correct sodium slowly.

Do not exceed 12 mEq/L increase in 24 hours (prevents osmotic demyelination).

Restrict fluids if fluid overload is present.

Monitor intake and output.

Obtain daily weights.

Monitor vital signs and level of consciousness.

Interprofessional Care

• Nephrology consultation for electrolyte management.

• Respiratory therapy for oxygen support if needed.

• Nutrition services for sodium-rich diet planning and fluid restriction.

Client Education

• Weigh daily.

• Report weight gain of 1–2 lb in 24 hours or 3 lb in one week.

• Follow prescribed high-sodium diet.

• Read food labels for sodium content.

• Track daily sodium intake.

Hyponatremia Complications

Severe Hyponatremia

• Seizures

• Coma

• Respiratory arrest

• Requires immediate treatment

Nursing Actions

• Goal is to raise serum sodium to reduce neurologic symptoms.

• Maintain airway and monitor vital signs.

• Implement seizure precautions.

• Monitor level of consciousness.

• Administer hypertonic oral or IV fluids as prescribed.

• Administer 3% sodium chloride cautiously with frequent sodium monitoring.

• Target sodium level not greater than 125 mEq/L during hypertonic therapy.

Hypernatremia

Serum sodium greater than 145 mEq/L.

Increased sodium causes hypertonicity of blood.

Water shifts out of cells, leading to cellular dehydration.

Can cause severe neurologic, endocrine, and cardiac disturbances.

Hypernatremia Risk Factors

Actual Sodium Excess

• Kidney failure

• Cushing’s syndrome

• Hyperaldosteronism

• Medications such as glucocorticoids

• Excessive oral sodium intake

Relative Sodium Excess Due to Decreased Fluid Volume

• Water deprivation or NPO status

• Hypertonic enteral feedings without adequate free water

• Diabetes insipidus

• Heatstroke

• Hyperventilation

• Watery diarrhea

• Burns

• Excessive sweating

Hypernatremia Findings

Thirst

• Intense thirst (cellular dehydration)

Vital Signs

• Hyperthermia

• Tachycardia

• Orthostatic hypotension

Neuromuscular

• Restlessness

• Irritability

• Muscle twitching progressing to weakness

• Decreased or absent deep tendon reflexes

• Seizures

• Coma

• Possible respiratory muscle weakness

Gastrointestinal

• Dry mucous membranes

• Nausea

• Vomiting

• Anorexia

• Occasional diarrhea

Hypernatremia Exams

Laboratory Findings

• Serum sodium greater than 145 mEq/L

• Serum osmolality greater than 300 mOsm/L

• Urine specific gravity increased

• Urine osmolality increased

Hypernatremia Care

Monitor level of consciousness and ensure safety.

Monitor vital signs and cardiac rhythm.

Auscultate lung sounds.

Provide oral hygiene and comfort measures for thirst.

Monitor intake and output.

Notify provider of decreased urine output.

Monitor potassium levels if diuretics are administered.

Fluid Management

Based on Serum Osmolality and Hemodynamic Status

• Dextrose 5% in 0.45% sodium chloride

  • Hypertonic before infusion

  • Becomes hypotonic after glucose metabolism

• 0.45% sodium chloride

  • Hypotonic solution

  • Gradual sodium reduction

  • Preferred if severe hyperglycemia is present

• Dextrose 5% in water or 0.9% sodium chloride

  • Isotonic solutions

Management of Excess Sodium

• Encourage water intake.

• Restrict sodium intake.

• Administer loop diuretics if renal excretion is impaired.

Interprofessional Care

• Nutrition services for low-sodium diet planning and fluid management.

Client Education

• Weigh daily.

• Report weight gain of 1–2 lb in 24 hours or 3 lb in one week.

• Follow a low-sodium diet.

• Read food labels for sodium content.

• Track daily sodium intake.

• Adhere to prescribed fluid intake.

• Avoid over-the-counter medications containing sodium bicarbonate.

Hypernatremia Complications

Severe Hypernatremia

• Seizures

• Convulsions

• Death if untreated

Nursing Actions

• Maintain airway patency.

• Monitor vital signs closely.

• Implement seizure precautions.

• Monitor level of consciousness frequently.

Potassium Imbalances

Physiology

• Potassium (K⁺) is the major intracellular cation.

• About 98% of potassium is inside cells.

• Essential for cell metabolism, nerve impulse transmission, and cardiac, lung, and skeletal muscle function.

• Maintains acid–base balance.

• Has a reciprocal relationship with sodium.

• Small potassium changes cause significant clinical effects.

Hypokalemia

Serum potassium less than 3.5 mEq/L.

Caused by potassium loss or shift of potassium into cells.

Hypokalemia Risk Factors

Actual Potassium Deficit

• Overuse of diuretics, digitalis, corticosteroids

• Increased aldosterone secretion

• Cushing’s syndrome

• GI losses: vomiting, diarrhea, prolonged NG suction

• Excessive laxative or tap water enema use (hypotonic fluid with isotonic GI losses)

• NPO status

• Kidney disease with impaired potassium reabsorption

Relative Potassium Deficit

• Alkalosis (potassium shifts into cells)

• Hyperinsulinism

• Hyperalimentation

• Total parenteral nutrition

• Water intoxication

• Older adults with frequent diuretic or laxative use

Hypokalemia Findings

Vital Signs

• Decreased blood pressure

• Weak, thready pulse

• Orthostatic hypotension

Neurologic

• Altered mental status

• Anxiety

• Lethargy progressing to confusion or coma

Cardiac

• Dysrhythmias

ECG Changes

• Flattened or inverted T waves

• Prominent U waves

• ST depression

• Prolonged PR interval

Gastrointestinal

• Hypoactive bowel sounds

• Nausea

• Vomiting

• Constipation

• Abdominal distention

• Possible paralytic ileus

Muscular

• Muscle weakness

• Decreased deep tendon reflexes

Respiratory

• Shallow respirations

• Risk for respiratory compromise

Hypokalemia Exams

Laboratory Findings

• Serum potassium less than 3.5 mEq/L

Diagnostic Procedures

Electrocardiogram

• Inverted or flat T waves

• ST depression

• Elevated U waves specific to hypokalemia

• Possible dysrhythmias

Hypokalemia Care

Administer prescribed potassium replacement.

Never give potassium IM or subcutaneously (tissue necrosis risk).

Monitor urine output before potassium administration.

Monitor respiratory status and breath sounds.

Continuous cardiac monitoring as indicated.

Monitor clients receiving digoxin (increased toxicity risk).

Monitor level of consciousness and ensure safety.

Assess bowel sounds and abdominal distention.

Monitor oxygen saturation above 95%.

Assess hand grasps for weakness.

Assess deep tendon reflexes.

Implement fall precautions.

Potassium Replacement

Oral Replacement

• Encourage potassium-rich foods:

  • Avocados

  • Broccoli

  • Dairy products

  • Dried fruit

  • Cantaloupe

  • Bananas

  • Fruit juices

  • Melon

  • Lean meats

  • Milk

  • Whole grains

  • Citrus fruits

• Salt substitutes are high in potassium.

• Administer oral potassium supplements as prescribed.

IV Potassium Supplementation

• Never give IV push or bolus (cardiac arrest risk).

• Maximum rate: 10 mEq per hour.

• Maximum concentration: 1 mEq per 10 mL solution.

• Monitor IV site for phlebitis (tissue irritation).

Interprofessional Care

• Nephrology for electrolyte management.

• Respiratory therapy for oxygen support.

• Nutrition services for potassium-rich diet planning.

• Cardiology for dysrhythmia management.

Client Education

• Identify potassium-rich foods.

• Avoid excessive use of diuretics and laxatives unless prescribed.

• Adhere to prescribed potassium therapy.

Hypokalemia Complications

Respiratory Failure

• Due to respiratory muscle weakness

Nursing Actions

• Maintain airway patency.

• Monitor vital signs.

• Monitor for hypoxemia and hypercapnia.

• Assist with intubation and mechanical ventilation if indicated.

Cardiac Arrest

• Due to severe dysrhythmias

Nursing Actions

• Continuous cardiac monitoring.

• Treat dysrhythmias promptly.

Hyperkalemia

Serum potassium greater than 5.0 mEq/L.

Caused by increased potassium intake, movement of potassium out of cells, or impaired renal excretion.

High risk for life-threatening dysrhythmias and cardiac arrest.

Rare in clients with normal kidney function.

Hyperkalemia Risk Factors

Actual Potassium Excess

• Older adults (↓ renin and aldosterone; ↑ use of salt substitutes, ACE inhibitors, potassium-sparing diuretics)

• Excess intake of high-potassium foods or salt substitutes

• Excessive or rapid potassium replacement (oral or IV)

• RBC transfusions

• Adrenal insufficiency

• ACE inhibitors

• Potassium-sparing diuretics

• Kidney failure

Relative Potassium Excess (Shift Out of Cells)

• Decreased insulin production

• Metabolic acidosis (diabetic ketoacidosis)

• Tissue damage (sepsis, trauma, surgery, fever, myocardial infarction)

• Hyperuricemia

Hyperkalemia Findings

Vital Signs

• Slow, irregular pulse

• Hypotension

Neuromuscular

• Restlessness

• Irritability

• Muscle weakness progressing to ascending flaccid paralysis

• Paresthesia

Cardiac

• Dysrhythmias

ECG Changes

• Peaked T waves

• Widened QRS

• Prolonged PR

• Ventricular dysrhythmias

• Possible ventricular fibrillation or asystole

Gastrointestinal

• Increased motility

• Diarrhea

• Hyperactive bowel sounds

Renal

• Oliguria

Hyperkalemia Exams

Laboratory Findings

• Serum potassium greater than 5.0 mEq/L

• Hemoglobin and hematocrit

  • Increased with dehydration

  • Decreased with kidney failure

• BUN and creatinine increased with kidney failure

• Arterial blood gases

  • Metabolic acidosis (pH less than 7.35) with kidney failure

Diagnostic Procedures

Electrocardiogram

• Peaked T waves

• Widened PR and QRS

• Absent or flattened P waves

• ST depression

• Possible heart block, ventricular fibrillation, or asystole

Hyperkalemia Care

Priority is prevention of falls, early recognition of cardiac complications, and health teaching.

Monitor cardiac rhythm continuously.

Monitor intake and output.

Assess muscle strength and weakness.

Monitor for GI symptoms such as nausea and intestinal cramping.

Stop potassium infusions immediately if potassium is elevated.

Maintain IV access.

Discontinue potassium supplements.

Promote potassium-restricted diet.

Monitor serum potassium levels frequently.

Monitor for hypokalemia during treatment.

Severe Management

• Administer calcium gluconate as prescribed (cardiac membrane stabilization).

• Dialysis may be required for severe or chronic hyperkalemia.

Shift Potassium Into Cells

• IV dextrose with regular insulin (drives potassium into cells).

• Sodium bicarbonate if metabolic acidosis is present.

Prevention

• Avoid whole blood or packed RBC transfusions in clients with impaired renal function when possible.

• Avoid high-potassium foods:

  • Citrus fruits

  • Legumes

  • Whole grains

  • Lean meats

  • Milk

  • Eggs

  • Cocoa

  • Some cola beverages

• Teach clients to read food labels for potassium content.

• Low-potassium foods include:

  • Fruits: apples, cranberries, grapes, canned peaches, cranberry or grape juice

  • Vegetables: lettuce, cabbage, cucumbers, green peppers, sweet onions, green peas, green beans

  • Leaching vegetables reduces potassium content (peel, soak, drain, boil)

  • Refined grains instead of whole grains

  • Beverages: brewed tea, coffee, ginger ale, root beer

  • Other: applesauce, angel food cake, butter, margarine, hard candy, sugar, honey

• Clients with kidney disease on potassium-sparing diuretics should avoid potassium supplements and salt substitutes.

Interprofessional Care

• Nephrology for dialysis and electrolyte management.

• Nutrition services for potassium-restricted diet planning.

• Cardiology for dysrhythmia management.

Client Education

• Identify low-potassium food choices.

• Read food labels for potassium content.

• Avoid salt substitutes containing potassium.

• Hold potassium supplements unless directed by the provider.

Hyperkalemia Meds

To Increase Potassium Excretion

Loop Diuretics (Furosemide)

• Use only if kidney function is adequate.

• Increase renal potassium loss.

• Monitor intake and output.

Cation-Exchange Resins

• Sodium polystyrene sulfonate

• Binds potassium in the GI tract and excretes it in stool.

• Dialysis may be required if potassium remains critically high.

Beta-2 Agonists (Albuterol)

• Shifts potassium into cells.

• Monitor for tachycardia and chest pain.

Patiromer

• Binds potassium in the GI tract.

• Used for chronic hyperkalemia.

IV Insulin and Glucose

• Shifts potassium into cells.

Hyperkalemia Complications

Cardiac Arrest

Nursing Actions

• Treat dysrhythmias immediately.

• Maintain continuous cardiac monitoring.

A nurse is teaching a class about electrolyte imbalances. The nurse should include that which of the following conditions places a client at risk for hyperkalemia?

a

Diabetic ketoacidosis

b

Heart failure

c

Cushing’s syndrome

d

Thyroidectomy

a

Diabetic ketoacidosis

Other Electrolyte Imbalances

Calcium: hypocalcemia, hypercalcemia

Chloride: hypochloremia, hyperchloremia

Magnesium: hypomagnesemia, hypermagnesemia

Phosphorus: hypophosphatemia, hyperphosphatemia

Hypocalcemia and hypomagnesemia have high clinical risk due to neuromuscular and cardiac effects.

Hypocalcemia

Total serum calcium less than 9.0 mg/dL.

Hypocalcemia Risk Factors

Actual Calcium Deficit

• Inadequate calcium intake

• Lactose intolerance

• Malabsorption syndromes

• Chronic diarrhea or steatorrhea

• Inadequate vitamin D intake

• End-stage kidney disease

• Wound drainage

Relative Calcium Deficit

• Alkalosis

• Acute pancreatitis

• Hyperproteinemia

• Hyperphosphatemia

• Immobilization

• Calcium-chelating treatments

  • Citrate

  • Mithramycin

  • Sodium cellulose phosphate

  • Penicillamine

  • Pamidronate

• Parathyroid gland removal or damage

• Prolonged immobility

Hypocalcemia Findings

Neuromuscular

• Tetany (increased neuromuscular excitability)

• Paresthesia of fingers and lips

• Muscle twitching

• Painful muscle spasms at rest, especially calves or feet

• Seizures

• Hyperactive deep tendon reflexes

• Positive Chvostek’s sign

• Positive Trousseau’s sign

Risk Indicators

• History of thyroid or upper neck surgery

• History of neck or chest irradiation

Cardiovascular

• Prolonged QT interval

• Prolonged ST segment

• Risk for torsades de pointes

• Decreased myocardial contractility

• Bradycardia and hypotension in severe cases

Gastrointestinal

• Hyperactive bowel sounds

• Diarrhea

• Abdominal cramping

Hypocalcemia Exams

Laboratory Findings

• Serum calcium less than 9.0 mg/dL

• Low albumin can falsely lower total calcium

• Ionized calcium reflects true calcium status when albumin is low

Diagnostic Procedures

• ECG showing prolonged QT and ST intervals

Hypocalcemia Care

Administer oral or IV calcium supplements as prescribed.

Administer vitamin D to improve calcium absorption.

Implement seizure and fall precautions.

Reduce environmental stimulation.

Keep emergency equipment available.

Encourage calcium-rich foods:

• Dairy products

• Yogurt

• Canned salmon

• Sardines

• Fresh oysters

• Dark leafy green vegetables

Treat severe hypocalcemia with IV calcium gluconate or calcium chloride.

Dilute IV calcium in dextrose 5% in water.

Administer slowly via infusion pump.

Monitor cardiac rhythm closely.

Rapid administration can cause cardiac arrest.

Interprofessional Care

• Endocrinology for electrolyte regulation.

• Respiratory therapy for oxygen support if needed.

• Nutrition services for calcium-rich diet planning.

• Cardiology for dysrhythmia management.

Client Education

• Consume calcium-rich foods such as milk and yogurt.

• Read food labels to increase dietary calcium intake.

A nurse is teaching a class about electrolyte imbalances.

Match the electrolyte imbalance with the associated manifestations.

Hyponatremia

Hypocalcemia

Hyperkalemia​​​​​​​

Hypokalemia

Hypoactive bowel sounds

ECG with tall, peaked t-waves

Positive Trousseau’s sign

Bounding pulse

Hypoactive bowel sounds

Hypokalemia

ECG with tall, peaked t-waves

Hyperkalemia​​​​​​​

Positive Trousseau’s sign

Hypocalcemia

Bounding pulse

Hyponatremia

The nurse is assessing the client for Chvostek’s sign. Which of the following actions should the nurse take?

a

Apply a blood pressure cuff to the client’s arm.

b

Place a stethoscope bell over the client’s carotid artery.

c

Ask the client to lower their chin to their chest.

d

Tap lightly on the client’s cheek.

d

Tap lightly on the client’s cheek.

The nurse is assessing the client who reports nausea, vomiting, and weakness. Which of the following findings are manifestations of hypocalcemia?

Select all that apply.

a

Tingling in fingers

b

Poor skin turgor

c

Abdominal pain

d

Elevated temperature

e

Muscle twitching

a

Tingling in fingers

c

Abdominal pain

e

Muscle twitching

Hypomagnesemia

Serum magnesium less than 1.3 mg/dL.

Hypomagnesemia Risk Factors

Celiac disease or Crohn’s disease (malabsorption)

Malnutrition or inadequate magnesium intake

Chronic alcohol use (increased renal magnesium excretion)

Diarrhea, steatorrhea, or chronic laxative use

Citrate exposure from blood products

Myocardial infarction or heart failure

Concurrent hypokalemia or hypocalcemia

Medications:

• Aminoglycoside antibiotics

• Cisplatin

• Cyclosporine

• Amphotericin B

Hypomagnesemia Findings

Cardiovascular

• Increased risk for dysrhythmias

• Possible hypertension

• ECG changes:

  • Premature ventricular contractions

  • Flat or inverted T waves

  • ST depression

  • Prolonged PR interval

  • Widened QRS

Neuromuscular

• Increased nerve impulse transmission

• Hyperactive deep tendon reflexes

• Paresthesia

• Muscle tetany

• Seizures

• Positive Chvostek’s sign

• Positive Trousseau’s sign

Gastrointestinal

• Hypoactive bowel sounds

• Constipation

• Abdominal distention

• Paralytic ileus

Neuropsychiatric

• Depressed mood

• Apathy

• Agitation

Hypomagnesemia Care

Correct concurrent electrolyte imbalances, especially potassium and calcium.

Encourage magnesium-rich foods for mild deficiency:

• Dark green vegetables

• Nuts

• Whole grains

• Seafood

• Peanut butter

• Cocoa

Discontinue magnesium-depleting medications when possible:

• Loop diuretics

• Osmotic diuretics

• Phosphorus-containing medications

Administer oral magnesium for mild hypomagnesemia.

Administer IV magnesium sulfate for severe hypomagnesemia.

Use an infusion pump.

Do not exceed 150 mg per minute or 67 mEq over 8 hours.

Monitor deep tendon reflexes hourly during IV administration.

Monitor clients taking digoxin closely (low magnesium increases digoxin toxicity risk).

Keep calcium gluconate available to reverse magnesium toxicity if needed.

Chapter 46: Acid-Base Imbalances

Acid–base balance maintains hydrogen ion (H⁺) homeostasis in body fluids

Small changes in H⁺ significantly affect cellular function

Arterial pH reflects combined respiratory and renal function

Normal arterial pH: 7.35–7.45

Relationship

• ↑ H⁺ = ↓ pH (acidic)

• ↓ H⁺ = ↑ pH (alkaline)

ABGs assess acid–base status

• CO₂ regulated by lungs

• HCO₃⁻ regulated by kidneys

Maintenance of Acid–Base Balance

Chemical Buffers (First Line of Defense)

• Bicarbonate system and intracellular buffers

• Protein buffers (albumin, globulins)

• Bind or release H⁺ as needed

• Rapid response to pH changes

Respiratory Buffers (Second Line of Defense)

• Control H⁺ via CO₂ elimination

• Chemoreceptors sense CO₂ changes and adjust respirations

• Hyperventilation

  • Triggered by ↑ CO₂

  • ↓ H⁺ via CO₂ exhalation

• Hypoventilation

  • Triggered by ↓ CO₂

  • ↑ H⁺ via CO₂ retention

Renal Buffers (Third Line of Defense)

• Slowest but most effective and longest lasting

• Regulate bicarbonate reabsorption or excretion

• Can generate new bicarbonate

• Responses

  • pH < 7.35: ↑ H⁺ → reabsorb and produce HCO₃⁻

  • pH > 7.45: ↓ H⁺ → excrete HCO₃⁻

Compensation

• Body attempts to normalize pH using lungs and kidneys

• Full compensation: pH returns to 7.35–7.45

• Partial compensation: pH remains abnormal

Types of Acid–Base Imbalances

• Respiratory acidosis

• Respiratory alkalosis

• Metabolic acidosis

• Metabolic alkalosis

Health Promotion and Disease Prevention

• Balanced diet and regular physical activity

• Limit alcohol intake

• Adequate hydration (6–8 cups water daily)

• Maintain healthy weight

• Smoking cessation

Compensation (image)

Respiratory Acidosis (Hypoventilation)

Causes

• Respiratory depression (opioids, anesthetics, poisons)

• CNS disorders (stroke, brain tumor, trauma, neuromuscular disease)

• Impaired chest expansion (obesity, pneumothorax, hemothorax, flail chest)

• Airway obstruction (edema, mucus, foreign body, lymph node enlargement)

• Alveolar-capillary impairment (pulmonary embolism, ARDS, pulmonary edema)

• Inadequate mechanical ventilation

ABG Findings

• ↑ CO₂

• ↑ or normal H⁺ (↓ pH)

Manifestations

• Vital signs: early tachycardia and hypertension, late bradycardia and hypotension

• Dysrhythmias (ventricular fibrillation possible with anesthesia)

• Neurologic: anxiety, confusion → lethargy, coma

• Respiratory: shallow, rapid, ineffective breathing

• Skin: pale or cyanotic

Nursing Care

• Oxygen therapy

• Maintain patent airway

• Improve ventilation and gas exchange

• Positioning, breathing techniques

• Ventilatory support, bronchodilators, mucolytics

Respiratory Alkalosis (Hyperventilation)

Causes

• Anxiety, fear, pain

• Intracranial trauma

• Salicylate toxicity

• Excessive mechanical ventilation

• Hypoxemia (high altitude, shock, early asthma, early pneumonia)

ABG Findings

• ↓ CO₂

• ↓ or normal H⁺ (↑ pH)

Manifestations

• Vital signs: tachypnea

• Neurologic: dizziness, tingling, numbness, tinnitus, possible LOC

• Cardiovascular: tachycardia, atrial or ventricular dysrhythmias

• Respiratory: rapid, deep respirations

Nursing Care

• Treat underlying cause

• Oxygen if hypoxemic

• Anxiety reduction

• Rebreathing techniques

Metabolic Acidosis

Causes

• Excess acid production

  • Diabetic ketoacidosis

  • Starvation

  • Lactic acidosis (exercise, seizures, hypoxia)

• Excess acid ingestion

  • Ethanol, methanol

  • Aspirin toxicity

• Decreased acid excretion

  • Kidney failure

• Decreased bicarbonate production

  • Kidney failure

  • Pancreatitis

• Loss of bicarbonate

  • Diarrhea

• Impaired liver or pancreatic function

ABG Findings

• ↓ HCO₃⁻

• ↑ H⁺ (↓ pH)

Manifestations

• Dysrhythmias

• Vital signs: bradycardia, hypotension, weak pulses, tachypnea

• Neurologic: headache, confusion, drowsiness

• Respiratory: Kussmaul respirations (deep, rapid)

• Skin: warm, dry, pink

Nursing Care

• Treat cause

• DKA: administer insulin

• GI loss: antidiarrheals and rehydration

• Severe low HCO₃⁻: sodium bicarbonate (1 mEq/kg)

Metabolic Alkalosis

Causes

• Base excess

  • Excess antacid intake

  • IV bicarbonate, blood transfusions, TPN

• Acid loss

  • Prolonged vomiting

  • NG suction

• Potassium depletion

  • Thiazide diuretics

  • Laxative overuse

  • Hyperaldosteronism, Cushing syndrome

• Increased digitalis toxicity

ABG Findings

• ↑ HCO₃⁻

• ↓ H⁺ (↑ pH)

Manifestations

• Vital signs: tachycardia, normotension or hypotension

• Dysrhythmias (worsen as pH increases)

• Neurologic: numbness, tingling, tetany, muscle weakness, confusion, seizures

• Respiratory: hypoventilation from muscle weakness

Nursing Care

• Treat cause

• GI losses: antiemetics, IV fluids, electrolyte replacement

• Potassium depletion: stop causative agent and replace electrolytes

Diagnostic Procedures for Acid–Base Imbalances

Step 1: Assess pH

• pH < 7.35: Acidosis

• pH > 7.45: Alkalosis

Step 2: Assess PaCO₂ and HCO₃⁻ Together

• Identify which value is within normal range and which is abnormal

• The abnormal value indicates the primary imbalance

• PaCO₂

  • Normal: 35–45 mm Hg

  • < 35 or > 45 indicates respiratory origin

• HCO₃⁻

  • Normal: 22–26 mEq/L

  • < 22 or > 26 indicates metabolic origin

Step 3: Name the Imbalance

• Combine pH result with the abnormal PaCO₂ or HCO₃⁻ value

Step 4: Assess Oxygenation

• Evaluate PaO₂ and SaO₂

• Values below expected range indicate hypoxemia

Step 5: Determine Compensation

• Uncompensated

  • pH abnormal

  • Either PaCO₂ or HCO₃⁻ abnormal

• Partially compensated

  • pH abnormal

  • PaCO₂ and HCO₃⁻ both abnormal

• Fully compensated

  • pH normal

  • PaCO₂ and HCO₃⁻ both abnormal

• Use pH direction to identify the primary problem

  • pH < 7.40: acidosis

  • pH > 7.40: alkalosis

Respiratory Acidosis (image)

Respiratory Alkalosis (image)

Metabolic Acidosis (image)

Metabolic Alkalosis (image)

A nurse is teaching a group of nurses about conditions that can cause metabolic acidosis. Which of the following conditions should the nurse include? 

a

Diabetic ketoacidosis

b

Myasthenia gravis

c

Asthma

d

Laxative overuse

a

Diabetic ketoacidosis

A nurse is reviewing ABGs on a client who has vomited for 24 hr. Which of the following acid‑base imbalances should the nurse expect?

a

Respiratory acidosis

b

Respiratory alkalosis

c

Metabolic acidosis

d

Metabolic alkalosis

d

Metabolic alkalosis

Classic ABG Patterns

Normal (Homeostasis)

• pH: 7.35–7.45

• PaCO₂: 35–45

• HCO₃⁻: 22–26

Respiratory Acidosis

• pH < 7.35

• PaCO₂ > 45

• HCO₃⁻ normal

Metabolic Acidosis

• pH < 7.35

• PaCO₂ normal

• HCO₃⁻ < 22

Respiratory Alkalosis

• pH > 7.45

• PaCO₂ < 35

• HCO₃⁻ normal

Metabolic Alkalosis

• pH > 7.45

• PaCO₂ normal

• HCO₃⁻ > 26

Acid-Base Imbalance Care

Treat the underlying cause of the imbalance

Tailor interventions to the client’s condition and severity

Interprofessional Care

• Respiratory therapy

  • Oxygen therapy

  • Breathing treatments

  • ABG monitoring

• Pulmonology consultation for complex respiratory management

Client Education

• Follow prescribed diet and dialysis regimen if renal disease present

• Daily weights

  • Report 1–2 lb (0.5–0.9 kg) gain in 24 hours

  • Report 3 lb (1.4 kg) gain in one week

• Smoking cessation counseling

• Take medications as prescribed

• COPD management adherence

• Arrange home oxygen if indicated

Acid-Base Imbalance Complications

Seizures

Coma

Respiratory arrest

Nursing Actions

• Implement seizure precautions as needed

• Initiate life-support measures when indicated

A nurse is teaching a group of nurses about acid-base imbalances. Match the acid-base imbalance with the ABG result.

Respiratory alkalosis

Metabolic alkalosis

Respiratory acidosis

Metabolic acidosis

pH 7.30 PaCO ₂ 48 mm Hg HCO ₃ − 26 mEq/L

pH 7.50 PaCO ₂ 28 mm Hg HCO ₃ − 24 mEq/L

pH 7.32 PaCO ₂ 35 mm Hg HCO ₃ - 18 mEq/L

pH 7.50 PaCO ₂ 38 mm Hg HCO 3 − 30 mEq/L

pH 7.30 PaCO ₂ 48 mm Hg HCO ₃ − 26 mEq/L

Respiratory acidosis

pH 7.50 PaCO ₂ 28 mm Hg HCO ₃ − 24 mEq/L

Respiratory alkalosis

pH 7.32 PaCO ₂ 35 mm Hg HCO ₃ - 18 mEq/L

Metabolic acidosis

pH 7.50 PaCO ₂ 38 mm Hg HCO 3 − 30 mEq/L

Metabolic alkalosis

A nurse is caring for a client who was in a motor‑vehicle accident and reports chest pain and difficulty breathing. A chest x‑ray reveals the client has a pneumothorax. Which of the following ABG results should the nurse expect?

a

pH 7.25 PaCO₂ 52 mm Hg HCO₃⁻ 24 mEq/L

b

pH 7.42 PaCO₂ 38 mm Hg HCO₃⁻ 23 mEq/L

c

pH 7.30 PaCO₂ 36mm Hg HCO₃⁻ 18mEq/L

d

pH 7.50 PaCO₂ 29 mm Hg HCO₃⁻ 26 mEq/L

a

pH 7.25 PaCO₂ 52 mm Hg HCO₃⁻ 24 mEq/L