11/24/2009

Fluid & Electrolytes

The Basics

Fluid Balance

Sodium 135‐145 meq/L

• Imbalances typically associated with parallel changes in osmolality • Plays a major role in – ECF volume and concentttiration – Generation and transmission of nerve impulses – Acid–base balance

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Hypernatremia

• Elevated serum sodium occurring with water loss or sodium gain • Causes hyperosmolality leading to cellular dehydration • Primary protection is thirst from hypothalamus

Differential Assessment of ECF Volume

Hypernatremia

• Manifestations – Thirst, lethargy, agitation, seizures, and coma • Impaired LOC • Produced by clinical states – Central or nephrogenic diabetes insipidus – Serum sodium levels must be reduced gradually to avoid cerebral edema

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Nursing Management Nursing Diagnoses • Potential complication: seizures and coma leading to irreversible brain damage • Management • Treat undliderlying cause • If oral fluids cannot be ingested, IV solution of 5% dextrose in water or hypotonic saline • Diuretics

Hyponatremia

• Results from loss of sodium‐containing fluids or from water excess • Manifestations – CfiConfusion, nausea, vomiting, seizures, and coma

Nursing Management Nursing Diagnoses • Risk for injury • Potential complication: severe neurologic changes • Management • Abnormal fluid loss – Fluid replacement with sodium‐containing solution • Caused by water excess – Fluid restriction is needed • Severe symptoms (seizures) – Give small amount of IV hypertonic saline solution (3% NaCl)

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Potassium 3.5‐5.5 meq/L

• Major ICF cation • Necessary for – Transmission and conduction of nerve and muscle impulses – Maintenance of cardiac rhythms – Acid–base balance • Sources – Fruits and vegetables (bananas and oranges) – Salt substitutes – Potassium medications (PO, IV) – Stored blood

Hyperkalemia

• High serum potassium caused by – Massive intake – Impaired renal excretion – Shift from ICF to ECF • Common in massive cell destruction – Burn, crush injury, or tumor lysis • Manifestations – Weak or paralyzed skeletal muscles – Ventricular fibrillation or cardiac standstill – Abdominal cramping or diarrhea

Nursing Management Nursing Diagnoses • Risk for injury • Potential complication: dysrhythmias • Management • Eliminate oral and parenteral K intake • Increase elimination of K (diuretics, dialysis, Kayexalate) • Force K from ECF to ICF by IV insulin or sodium bicarbonate

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Hypokalemia

• Low serum potassium caused by – Abnormal losses of K+ via the kidneys or gastrointestinal tract – – Metablibolic alka los is • Manifestations – Most serious are cardiac – Skeletal muscle weakness – Weakness of respiratory muscles – Decreased gastrointestinal motility

Nursing Management Nursing Diagnoses • Risk for injury • Potential complication: dysrhythmias • KCl supplements orally or IV • Should not exceed 10 to 20 mEq/hr – To prevent and cardiac arrest

Calcium 4‐5 meq/L

• Obtained from ingested foods • More than 99% combined with phosphorus and concentrated in skeletal system • Inverse relationship with phosphorus

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Calcium

• Bones are readily available store • Blocks sodium transport and stabilizes cell membrane

• Functions – Transmission of nerve impulses – Myocardial contractions – Blood clotting – Formation of teeth and bone – Muscle contractions

Calcium • Balance controlled by – – Calcitonin – Vitamin D • High serum calcium levels caused by – Hyperparathyroidism – Malignancy – Vitamin D overdose – Prolonged immobilization

Hypercalcemia

• Manifestations – Decreased memory – Confusion – Disorientation – Fatigue – Constipation

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Nursing Management Nursing Diagnoses • Risk for injury • Potential complication: dysrhythmias • Management: • Excretion of Ca with loop diuretic • Hydration with isotonic saline infusion • Synthetic calcitonin • Mobilization

Hypocalcemia

• Low serum Ca levels caused by – Decreased production of PTH – Acute pancreatitis – Multiple blood transfusions – Alkalosis – Decreased intake • Manifestations – Positive Trousseau’s or Chvostek’s sign – Laryngeal stridor – Dysphagia – Tingling around the mouth or in the extremities

Nursing Management Nursing Diagnoses • Risk for injury • Potential complication: fracture or respiratory arrest • Management • Treat cause • Oral or IV calcium supplements • Treat pain and anxiety to prevent hyperventilation‐induced respiratory alkalosis

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Phosphate 3‐4.5

• Primary anion in ICF • Essential to function of muscle, red blood cells, and nervous system • Deposited with calcium for bone and tooth structure • Involved in acid–base buffering system, ATP production, and cellular uptake of glucose • Maintenance requires adequate renal functioning

Hyperphosphatemia

3 • High serum PO4 caused by – Acute or chronic renal failure – Chemotherapy – Excessive ingestion of phosphate or vitamin D

Hyperphosphatemia

• Manifestations – Calcified deposition in soft tissue such as joints, arteries, skin, kidneys, and corneas – Neuromuscular irritability and • Management – Identify and treat underlying cause 3 – Restrict foods and fluids containing PO4 – Adequate hydration and correction of hypocalcemic conditions

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Hypophosphatemia

3 • Low serum PO4 caused by – Malnourishment/malabsorption – Alcohol withdrawal – Use of phosphate‐binding antacids – During parenteral nutrition with inadequate replacement

Hypophosphatemia

• Manifestations – CNS depression – Confusion – Muscle weakness and pain – Dysrhythmias – Cardiomyopathy • Management – Oral supplementation 3 – Ingestion of foods high in PO4 – IV administration of sodium or potassium phosphate

Magnesium 1.5‐2.5 meq/L

• 50% to 60% contained in bone • Coenzyme in metabolism of protein and carbohydrates • Factors that regulate calilcium blbalance appear to influence magnesium balance

• Acts directly on myoneural junction • Important for normal cardiac function

9 11/24/2009

Hypermagnesemia

• High serum Mg caused by – Increased intake or ingestion of products containing magnesium when renal insufficiency or failure is present

Hypermagnesemia

• Manifestations – Lethargy or drowsiness – Nausea/vomiting – Impaired reflexes – Respiratory and cardiac arrest • Management – Prevention – Emergency treatment • IV CaCl or calcium gluconate – Fluids to promote urinary excretion

Hypomagnesemia

• Low serum Mg caused by – Prolonged fasting or starvation – Chronic alcoholism – Fluid loss from gastrointestinal tract – Prolonged parenteral nutrition without supplementation – Diuretics

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Hypomagnesemia

• Manifestations – Confusion – Hyperactive deep tendon reflexes – Tremors – Seizures – Cardiac dysrhythmias • Management – Oral supplements – Increase dietary intake – Parenteral IV or IM magnesium when severe

Electrolyte Disorders

Electrolyte Excess Deficit Sodium (Na) Hypernatremia Thirst CNS deterioration CNS deterioration Increased interstitial fluid

Potassium (K) Hyperkalemia Ventricular fibrillation Bradycardia ECG changes ECG changes CNS changes CNS changes

Electrolyte Disorders Signs and Symptoms Electrolyte Excess Deficit Calcium (Ca) Hypercalcemia Thirst Tetany CNS deterioration Chvostek’sChvostek’s,, Trousseau’s Increased interstitial fluid signs Muscle twitching CNS changes ECG changes Magnesium (Mg) Hypermagnesemia Hypomagnesemia Loss of deep tendon reflexes Hyperactive DTRs (DTRs) CNS changes Depression of CNS Depression of neuromuscular function

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