Life-Threatening Asthma & Acute COPD Exacerbation

Upright positioning (tripod). Asthma: High-flow O₂ via non-rebreather or HFNC (40–60 L/min) to target SpO₂ 93–95%. COPD: Venturi mask (24–28%) or nasal cannula to target SpO₂ 88–92%. Continuous Albuterol (Salbutamol): 10–15 mg/hr via vibrating mesh/jet nebulizer + Ipratropium bromide 0.5 mg q20min × 3 doses.

Maximizes functional residual capacity (FRC) via diaphragmatic descent. Prevents Haldane effect and V̇/Q̇ mismatch worsening in COPD. Rapidly saturates bronchial β₂-adrenergic and blocks M₃-muscarinic receptors to reverse acute bronchospasm.

[1,2,3]

Establish two large-bore IVs (18G). Methylprednisolone: 125 mg IV push (Asthma) or 40–60 mg IV (COPD); or Hydrocortisone 200 mg IV; or Dexamethasone 16 mg IV/PO.

Upregulates β₂-receptor transcription (reversing tachyphylaxis within 1–2 hr) and suppresses nuclear factor kappa-B (NF-κB) eosinophilic/neutrophilic airway edema (peaks at 4–6 hr).

[1,2]

Magnesium Sulfate (MgSO₄): 2 g (16.2 mEq) IV in 50–100 mL D5W/NS infused over 20 min. Crashing Asthma / Anaphylactic Phenotype: Epinephrine 0.3–0.5 mg IM (1 mg/mL into anterolateral thigh) + IV Epinephrine drip (2–10 mcg/min) if impending arrest.

Mg²⁺ acts as a voltage-dependent L-type calcium channel blocker in bronchial smooth muscle and inhibits presynaptic acetylcholine release. Epinephrine adds α₁-mediated mucosal vasoconstriction to reduce subglottic/bronchial wall edema, decreasing radius reduction (r⁴).

[1,4]

COPD: BiPAP (IPAP 12–16 cmH₂O, EPAP 4–5 cmH₂O, FiO₂ titrated to SpO₂ 88–92%). Asthma (Alert/Fatigued): BiPAP or Delayed Sequence Intubation (DSI) with Ketamine 1 mg/kg IV slow push over 60 sec.

Applied extrinsic PEEP (EPAP) stents open collapsing distal airways ("waterfall effect"), offsetting intrinsic PEEP (PEEPi) and reducing the inspiratory threshold load required to trigger a breath. Ketamine provides bronchodilation while preserving airway reflexes.

[2,3,5]

Induction: Ketamine 1.5–2 mg/kg IV + Rocuronium 1.2 mg/kg IV. Tube Size: Largest possible ETT (≥ 8.0 mm ID) to minimize airway resistance. Initial Vent Settings: Volume Assist-Control (AC-VC), VT 6–8 mL/kg PBW, RR 8–10 breaths/min, Inspiratory Flow 80–100 L/min (square waveform), I:E ratio 1:4 to 1:5, PEEP 0–5 cmH₂O (Asthma) or 80% of measured PEEPi (COPD). Target Plateau Pressure (Pplat) < 30 cmH₂O.

Maximizes expiratory time (TE) to allow complete alveolar emptying, preventing breath-stacking, barotrauma, and obstructive shock (pulseless electrical activity from inferior vena cava/right ventricular collapse).

[5,6]