SEPT 10 Built from the handwritten pages you uploaded on 10 September 2026.

Asthma & bronchospasm

Grading acute severity, the anaesthetic agents that help and harm, and intraoperative bronchospasm.

Acute asthma severity

A normal PaCO₂ in acute asthma is not reassuring — it is life-threatening. The patient should be hyperventilating and hypocapnic. A normal CO₂ means they are tiring.
A silent chest is worse than a wheezy one. Wheeze requires airflow; no airflow, no wheeze.

Raised PaCO₂ (> 6 kPa), or requiring mechanical ventilation with raised inflation pressures.
Unable to speak at all, unconscious, no ventilation.

Acute severe → oxygen and bronchodilators (nebulised salbutamol and ipratropium, systemic steroid).
Life threatening (particularly a silent chest) → add magnesium, consider IV salbutamol or aminophylline, and prepare to intubate and ventilate.
PaCO₂ > 5.2 kPa with a rising trend is life threatening in this context and demands escalation, not repeat nebulisers.

Situation	Agent of choice	Why
Asthmatic — induction	Ketamine	Direct bronchodilatation, sympathomimetic, maintains airway tone
Asthmatic AND pregnant	Propofol	Ketamine raises uterine tone and blood pressure; propofol blunts airway reflexes well
Maintenance	Sevoflurane	Bronchodilator and least irritant of the volatiles
Avoid	Desflurane · thiopentone · atracurium · morphine · NSAIDs	Airway irritation, histamine release, or aspirin-sensitive asthma

Deep extubation, or extubation over an exchange catheter, avoids provoking spasm on emergence — the highest-risk moment.

Peak inspiratory pressure rises while plateau pressure stays the same. That gap is the signature of increased airway resistance — bronchospasm, a kinked or blocked tube, secretions.
If BOTH PIP and plateau rise together, the problem is compliance, not resistance — pneumothorax, endobronchial intubation, oedema, abdominal insufflation, chest wall rigidity.
Also: an upsloping (shark-fin) capnograph, prolonged expiration, wheeze, falling tidal volume in pressure control, rising CO₂.

100% oxygen, hand ventilate to feel compliance, exclude mechanical causes first (tube position, kinking, circuit).
Deepen anaesthesia — volatile or propofol or ketamine.
Salbutamol down the tube or IV, ipratropium, magnesium 2 g, adrenaline if severe, hydrocortisone (which will take hours).
Allow a long expiratory time (I:E 1:3 or longer), accept permissive hypercapnia, and watch for dynamic hyperinflation and gas trapping causing hypotension — disconnect briefly to confirm.

Normal CO₂ = life threatening

Silent chest = life threatening

PEFR <33% life threatening

Ketamine asthmatic induction

Propofol asthmatic + pregnant

PIP↑ plateau→ resistance

PIP↑ plateau↑ compliance

Built from your asthma severity table and induction agent pages. See also Pulmonary function tests.