Crash Asthma in the ICU

• Run back-to-back salbutamol nebs with ipratropium and give systemic steroids early; onset takes hours, so give NOW.
• In severe attacks add IV magnesium 2 g over 20 min; avoid sedatives unless intubating.
• A silent chest, rising PaCO₂, and exhaustion mean peri-arrest; a senior should intubate with ketamine.
• Once ventilated, allow long expiratory time and tolerate hypercapnia; if hypotension appears on the vent → disconnect (auto-PEEP).
• GINA 2026: give oxygen only if SpO₂ <92%, targeting ≤95%.

Mechanisms of Status Asthmaticus

• Asthma mechanisms: airway inflammation · bronchoconstriction · mucus plugging · rising airway resistance
• Pulmonary effects: dynamic hyperinflation · intrinsic PEEP · more physiologic deadspace · shunt · V/Q mismatch
• Cardiac effects: impaired diastolic filling · falling cardiac output
• Respiratory muscle effects: active exhalation · diaphragm at mechanical disadvantage · more accessory muscle work · more diaphragmatic work · impaired diaphragmatic perfusion
• Systemic effects: ↑ O₂ consumption · ↑ CO₂ production · normo/hypoxemia · hypo/hypercapnea · respiratory acidosis · metabolic acidosis