Hyperventilation → CO₂ washout → alkalaemia.
Compensation
- • Acute: HCO₃ falls 2 per 10 ΔPaCO₂
- • Chronic: HCO₃ falls 5 per 10 ΔPaCO₂
Causes
- • Hypoxia (early PE, pulmonary oedema, altitude)
- • Sepsis, fever, pain, anxiety
- • Salicylate poisoning (mixed picture)
- • CNS (stroke, tumour, infection)
- • Pregnancy, liver failure
- • Iatrogenic — over-ventilation
Treatment
- • Treat underlying cause — never simply rebreathe; risk masking PE or sepsis
