Synopsis
Recognise time-critical deterioration during adult anaesthesia, start a structured crisis response and apply the distinctive immediate actions for laryngospasm, perioperative anaphylaxis and malignant hyperthermia.
- For perioperative anaphylaxis, stop the suspected trigger, call for help, give 100% oxygen, treat profound hypotension with intravenous adrenaline in trained anaesthetic practice and rapid intravenous fluid, then start an infusion if boluses are insufficient. In this monitored adult perioperative setting, start CPR if systolic blood pressure is below 50 mmHg or cardiac arrest occurs.
- For malignant hyperthermia, stop volatile anaesthetics and suxamethonium, give 100% oxygen at maximum flow, hyperventilate, summon dantrolene and the MH pack, and begin active cooling when indicated.
- For laryngospasm, remove the stimulus, call for help, apply jaw thrust and continuous positive airway pressure with 100% oxygen, deepen anaesthesia and use neuromuscular blockade with tracheal intubation if obstruction persists.
Key red flags
Absent airflow with inspiratory effort, stridor, paradoxical movement or rapid desaturation around induction or emergence suggests complete laryngospasm and requires immediate treatment.
Abrupt hypotension, bronchospasm, tachycardia or bradycardia after exposure to a perioperative agent may be anaphylaxis even without rash or wheeze.
Unexplained rapidly increasing end-tidal carbon dioxide with tachycardia, increased oxygen use or muscle rigidity suggests malignant hyperthermia; temperature rise may be late.
A sudden absent capnography waveform requires immediate assessment of the patient, airway, breathing system and circulation; do not assume monitor failure.
Severe hypotension, low end-tidal carbon dioxide, pallor or surgical field loss can indicate major haemorrhage and may progress to cardiac arrest.
Any pulseless rhythm requires immediate high-quality CPR and the current adult advanced life-support algorithm while reversible causes are treated.
Stridor, tracheal tug, paradoxical chest movement, absent airflow or silent inspiratory effort near airway stimulation indicates partial or complete obstruction.
Unexpected hypotension, bronchospasm, tachycardia or bradycardia after a drug or material exposure can occur without visible rash.
Unexplained rising end-tidal carbon dioxide, tachycardia, increased oxygen consumption and rigidity precede a potentially late temperature rise.
Reasoning priorities
Track ventilation and circulation and identify rapid carbon dioxide rise, obstruction, disconnection or loss of output.
A rising trace supports hypermetabolism or hypoventilation in context; an absent trace can reflect apnoea, disconnection, tube displacement or arrest and demands immediate checks.
Worked reasoning
Minutes after induction drugs and an antibiotic, blood pressure collapses and airway pressure rises with poor gas exchange.
- Declare suspected perioperative anaphylaxis, call for help, stop suspected triggers, give 100% oxygen, secure the airway and confirm effective ventilation while pausing surgery if possible.
- In a trained adult anaesthetic setting, give titrated intravenous adrenaline for hypotension and rapid intravenous crystalloid, escalating to an adrenaline infusion if repeated boluses are ineffective.
- In the monitored adult perioperative setting, start immediate CPR if systolic blood pressure is below 50 mmHg or cardiac arrest occurs, follow the perioperative anaphylaxis or ALS algorithm, and reassess alternative causes including tube obstruction, haemorrhage and tension pneumothorax.
- After stabilisation, arrange critical-care observation as indicated. Take serum tryptase once stable, request another sample 1–4 hours after symptom onset and obtain baseline at least 24 hours later; do not delay resuscitation for sampling. Record all exposures and refer to a specialist anaesthetic allergy service.