Respiratory Disorders
Interpret this: hyperventilation effect.
Hyperventilation ↓ CO₂ → respiratory alkalosis.
Define metabolic acidosis.
Low HCO₃⁻ → low pH.
Partial Compensation
Opposite system is abnormal AND pH still abnormal.
pH: 7.48
PaCO₂: 40
HCO₃⁻: 32
Metabolic alkalosis
pH is high → alkalosis
HCO₃⁻ is high → metabolic cause
CO₂ is normal → no compensation
Kussmaul respirations, lethargy, & nausea.
Signs of metabolic acidosis.
Interpret this: hypoventilation effect.
Hypoventilation ↑ CO₂ → respiratory acidosis.
Define metabolic alkalosis.
High HCO₃⁻ → high pH.
Full compensation
pH is normal, but CO₂ and HCO₃⁻ are BOTH abnormal.
pH 7.34
PaCO₂ 58 mmHg
HCO₃⁻ 30 mEq/L
Respiratory acidosis with partial renal compensation
Why: pH ↓, CO₂ ↑ (primary problem), HCO₃⁻ ↑ = kidneys attempting to compensate
Insulin + IV fluids.
Nursing care for DKA-related acidosis.
Name 3 signs of respiratory alkalosis.
Dizziness, tingling, tetany, seizures, confusion, Dec K+, HA, GI symptoms.
Name 2 causes of metabolic acidosis.
DKA, lactic acidosis (renal failure, cancer, intense exercise), aspirin OD, Alcohol ingestion, pancreatitis.
The ‘lean rule’ for normal pH ABGs.
When pH is normal, look at which value (CO₂ or HCO₃⁻) matches the slight lean toward acid or alkaline to determine the cause.
pH: 7.31
PaCO₂: 52
HCO₃⁻: 24
Uncompensated respiratory acidosis
Why: pH ↓, CO₂ ↑ (cause), HCO₃⁻ normal
Improve ventilation, bronchodilators, oxygen, airway management.
Nursing care for respiratory acidosis
Name 3 signs of hypercapnic failure
Lethargy, confusion, headache, hypotension, tachycardia (early), bradycardia (late), arrhythmias, inc ICP.
(Respiratory acidosis)
Name 2 causes of metabolic alkalosis.
Vomiting, NG suction, diuretics, hyperaldosteronism, Cushings syndrome, blood transfusions.
Uncompensated ABG?
pH is abnormal, and one value is abnormal and the other is normal. One system caused the problem and the opposite system failed to fix it.
pH: 7.29
PaCO₂: 31
HCO₃⁻: 17
Metabolic acidosis with partial respiratory compensation
Why: pH ↓ matches HCO₃⁻ ↓, CO₂ ↓ = lungs helping
Treat anxiety/hypoxia, coach slow breathing, oxygen if needed.
Nursing care for respiratory alkalosis.
Give 2 causes of chronic respiratory acidosis.
COPD, sleep apnea, obesity, hypoventilation (chest trauma, airway obstruction, flail chest, Pneumothorax).
Explain why blood transfusion can cause alkalosis.
Citrate metabolizes into bicarbonate → increases pH.
pH: 7.42
PaCO₂: 28
HCO₃⁻: 18
Respiratory alkalosis with full metabolic compensation.
pH is normal but leans alkaline
CO₂ is low (alkalotic → respiratory problem)
HCO₃⁻ is low (acidotic → kidneys compensating)
pH: 7.50
CO2: 50
HCO3: 34.
Metabolic Alkalosis with partial respiratory compensation
Why: pH is Alkalosis (and abnormal), Co2 is Acidosis (and abnormal), HC03 is Alkalosis.
Confusion, seizures, hypoventilation, & dizziness.
Signs of metabolic alkalosis.