Dehydration
Dehydration causes and risk factors
Inadequate fluid intake (NPO, elderly, infants)
Excessive fluid loss (vomiting, diarrhea, sweating, diuretics, hemorrhage, fever, burns)
Medical conditions: diabetes insipidus, uncontrolled diabetes (polyuria), hyperventilation
fluid overload causes and risk factors
Excess IV fluids, rapid infusions
Heart failure, renal failure, liver cirrhosis
Excess sodium intake
Potassium safe administration
NEVER IV push → fatal
Dilute in IV fluids, infuse slowly (10 mEq/hr peripheral; 20 mEq/hr central line max)
Monitor cardiac rhythm, urine output (>30 mL/hr)
functions of sodium
Maintains fluid balance, nerve impulses, muscle contraction
Functions of potassium
Nerve/muscle (esp. cardiac) conduction, acid-base balance
calcium functions
Bones/teeth, clotting, muscle contraction, nerve transmission
functions of magnesium
Nerve/muscle function, cardiac stability, enzymatic reactions
Normal ABG values
pH: 7.35–7.45
PaCO₂: 35–45 mmHg
HCO₃⁻: 22–26 mEq/L
Assessment for dehydration
History of fluid loss
Monitor I&O, urine specific gravity (>1.030)
Labs: ↑ BUN, ↑ hematocrit, ↑ serum osmolality
fluid overload assessment
Daily weights
Lung sounds, edema, I&O
Labs: ↓ hematocrit, ↓ BUN, hyponatremia
Isotonic (same osmolality as blood plasma)
NS (0.9%), LR, D5W (initially)
→ Expands intravascular volume (for dehydration, hypovolemia, shock)
Causes (diuretics, GI losses, SIADH, water intoxication);
hypokalemia causes <3.5
(diuretics, vomiting, NG suction, diarrhea, insulin, alkalosis);
what causes hypocalcemia
hypoparathyroidism, Vit D deficiency, pancreatitis, CKD);
causes of hypomagnesemia
(alcoholism, diuretics, diarrhea, malnutrition);
Metabolic Acidosis Causes
DKA, renal failure, diarrhea, sepsis, shock
Symptoms: Kussmaul respirations, confusion, hypotension, arrhythmias, hyperkalemia
Compensation: ↑ RR to blow off CO₂
Interventions: Treat cause (insulin for DKA, dialysis for renal failure, bicarb if severe)
Symptoms of dehydration
Dry mucous membranes, poor skin turgor
Tachycardia, hypotension, orthostatic changes
Weak pulses
Oliguria, dark concentrated urine
Confusion, dizziness
Weight loss
fluid overload symptoms
Crackles, pulmonary edema, SOB, dyspnea
Bounding pulses, hypertension, tachycardia
JVD
Weight gain, peripheral edema
Confusion (dilutional hyponatremia)
Hypotonic (lower osmolality than plasma): 0.45% NS, D5W (after metabolism)
→ Moves water into cells (for cellular dehydration, DKA, HHS)
Symptoms of low sodium
confusion, seizures, headache, weakness, N/V; Interventions: fluid restriction, hypertonic saline (severe), seizure precautions
Symptoms of low potassium
muscle weakness, arrhythmias, flattened T waves, cramps, ileus; Interventions: PO/IV K+, monitor ECG, encourage K+ foods (bananas, oranges, potatoes, spinach)
symptoms of hypocalcemia
tetany, numbness, Chvostek’s/Trousseau’s sign, seizures, laryngospasm
Symptoms of hypomagnesmia
reflexes, tremors, seizures, arrhythmias, confusion;
Metabolic Alkalosis Causes:
Vomiting, NG suction, diuretics, excess antacids
Symptoms: Muscle cramps, tetany, dysrhythmias, hypokalemia signs
Compensation: ↓ RR to retain CO₂
Interventions: Replace K+, Cl-, fluids; stop causative agent
Interventions and education with dehydreation
Oral/IV fluids as ordered (isotonic fluids for hypovolemia: NS, LR)
Daily weights
Monitor vitals, labs, urine output
Education: adequate fluid intake, especially during illness/heat
fluid overload intervention / education
Restrict fluids & sodium
Diuretics (furosemide/Lasix)
Elevate HOB, give O2 PRN
Daily weights, strict I&O
Hypertonic (higher osmolality than plasma): 3% NS, D10W, D5NS
→ Pulls water out of cells (for hyponatremia, cerebral edema)
causes of hypernatremia (>145)
dehydration, excess Na, DI); Symptoms: thirst, dry mucosa, agitation, seizures; Interventions: hypotonic fluids, Na restriction, seizure precautions
what causes Hyperkalemia (>5.0)
(range 3.5-5.0)
(renal failure, K-sparing diuretics, ACE inhibitors, acidosis, trauma);
Interventions for hypocalcemia
Ca supplements/IV Ca gluconate, seizure precautions, encourage dairy/greens
hypomagnesemia low magnesium - interventions
Mg supplements/IV MgSO4, seizure precautions, diet (nuts, whole grains, green veggies)
Respiratory Acidosis Causes:
Hypoventilation (COPD, drug overdose, pneumonia, respiratory depression)
Symptoms: Hypoxia, headache, confusion, drowsiness, hyperkalemia
Compensation: Kidneys retain HCO₃⁻ (slow)
Interventions: Improve ventilation (O₂, bronchodilators, mechanical ventilation if needed)
Symptoms of hyperkalemia
peaked T waves, arrhythmias, muscle weakness; Interventions: calcium gluconate, insulin/glucose, diuretics, dialysis, avoid high-K foods
What causes Hypercalcemia
(hyperparathyroidism, malignancy, thiazide diuretics)
causes of Hypermagnesemia (>2.5)
Causes (renal failure, excessive Mg antacids/laxatives);
Respiratory Alkalosis Causes:
Hyperventilation (anxiety, fever, hypoxemia, pain)
Symptoms: Dizziness, tingling, tetany, seizures, hypokalemia signs
Compensation: Kidneys excrete HCO₃⁻
Interventions: Slow breathing, rebreathing into paper bag, anxiety management
hypercalcemia causes
muscle weakness, ↓ reflexes, constipation, kidney stones, confusion;
Symptoms of hypermagnesemia > 2.5:
↓ reflexes, hypotension, bradycardia, respiratory depression, cardiac arrest;
Electrolyte Relationships:
Calcium ⬆️ = Phosphate ⬇️ (inverse)
Potassium ⬆️ ↔ H+ ⬆️ (acidosis causes hyperkalemia)
Magnesium & Potassium often follow each other
hypercalcemia interventions
IV fluids, diuretics, bisphosphonates, calcitonin, encourage fluids
Interventions for hypermagnesemia
IV Ca gluconate, dialysis, avoid Mg-containing meds