Respiratory acidosis means alveolar hypoventilation: think drive (drugs, brain), pump (neuromuscular, chest wall, fatigue) or lungs (COPD, asthma). Respiratory alkalosis is hyperventilation from hypoxaemia, sepsis, pain, PE, liver failure, salicylates or pregnancy.
At the bedside
Timed steps- 1
Acute or chronic?
AcidosisUse the compensation rules: acute HCO3- +1 per 10 mmHg, chronic +3.5-4 per 10.
- 2
Find the cause
AcidosisSedatives/opioids (naloxone), neuromuscular weakness (GBS, MG, snake envenomation, organophosphates), obesity hypoventilation, COPD/asthma, ventilator settings.
- 3
Treat
AcidosisReverse drugs, NIV for COPD/obesity, intubate for coma or exhaustion; in ventilated patients increase minute ventilation (except permissive hypercapnia strategies).
- 4
Find the cause
AlkalosisHypoxaemia, sepsis (early), PE, pain/anxiety, CNS lesions, liver failure, salicylate toxicity (mixed with HAGMA), pregnancy, over-ventilation on the ventilator.
- 5
Treat the cause
AlkalosisDo not rebreathe into a bag; hypoxaemia must be excluded first.
Respiratory acidosis
Step 1 of ~3
Decision: Reduced drive (GCS low, opioids, sedatives)?
Based on Berend K, de Vries APJ, Gans ROB. Educational use; follow local protocol.
Evidence
- Compensation rules as in Berend 2014.
🇮🇳 India notes
- Neurotoxic snakebite (krait, cobra) and organophosphate poisoning are major causes of acute respiratory acidosis in rural India (modules 28-29).
References
Test yourself
Module quiz · score 70% to complete the module
Educational reference for trained clinicians. Check doses against your hospital protocol and the patient in front of you.