Intra-operative crises · Core17 / 21
Chlorhexidine anaphylaxis with arrest in an asthmatic46-year-old woman, 70 kg, asthma on inhaled budesonide
Anaphylaxis to arrest: IM then IV adrenaline, the asthmatic twist, glucagon
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Know this first
- Chlorhexidine hides in skin prep, urinary catheter lubricant and impregnated central lines.
- Skin signs are often absent; hypotension alone was the first sign in half of NAP6 cases.
- Adrenaline 0.5 mg IM first; if no response, 0.05–0.1 mg IV slowly; infusion 0.05–0.1 mcg/kg/min.
- Crystalloid boluses: grade 2 gets 0.5 L, grade 3 gets 1 L, repeated as needed.
- Start CPR when end-tidal CO2 falls below 20 mmHg.
The patient
46-year-old woman, 70 kg, asthma on inhaled budesonide; once had hives and lip swelling after a urinary catheter.
Elective laparoscopic cholecystectomy. After induction, a urinary catheter was inserted with lubricant gel and the skin prepped with chlorhexidine.
Five minutes later: BP 64/38, HR 128, SpO2 89%, peak airway pressure 38 cmH2O with a sloping capnograph; no rash visible under the drapes.
The examiner asks
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Consider
What is happening?
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- A 46-year-old asthmatic, minutes after catheter gel and chlorhexidine prep, before her cholecystectomy starts. Patient
- Hypotension, tachycardia and bronchospasm together: severe anaphylaxis until proven otherwise. Disease
- Her rash after a catheter fits chlorhexidine, found in catheter gel and skin prep. Stem trigger
- No rash doesn't exclude it; skin signs are often absent or hidden by drapes. Disease
- Her asthma can't explain the collapse in pressure.
Crisis
What do you do?
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- Anaphylaxis algorithm: life-threatening hypotension and bronchospasm in her. (Crisis)
- Call for help, stop surgery, remove the trigger: catheter out, chlorhexidine washed off.
- 100% oxygen through her tube; legs raised.
- Adrenaline 0.5 mg IM into the thigh; monitored and no response, 0.05–0.1 mg IV slowly, repeated.
- Crystalloid 1 L fast through a second large cannula, repeated as needed.
- Her bronchospasm: salbutamol 4–8 puffs into the tracheal tube, followed by 2 puffs each 10 minutes.
- Not settling: adrenaline infusion 0.05–0.1 mcg/kg/min, then vasopressin 2–10 units.
Crisis
Despite this, end-tidal CO2 falls to 12 mmHg and you feel no pulse; the monitor shows a narrow-complex rhythm at 130. What now?
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- Adult arrest algorithm: PEA from anaphylaxis, a non-shockable rhythm. (Crisis)
- CPR now; an end-tidal CO2 under 20 had already told me perfusion had failed.
- Adrenaline 1 mg IV straight away, repeated every 3–5 minutes.
- Fluid wide open: she has leaked much of her volume out of her vessels.
- No beta-blocker, so glucagon isn't part of her branch.
- High airway pressures in an asthmatic: I check for tension pneumothorax.
- Refractory: ECMO-supported CPR if it can be reached.
Plan
She regains a pulse. What happens afterwards?
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- Surgery cancelled; ICU, as biphasic reactions occur in up to 20%, from 1 to 72 hours. (After surgery)
- Tryptase within 45–90 minutes, then at 3 and 24 hours.
- Every exposure recorded with times: catheter gel, skin prep and each drug.
- Allergy clinic referral; testing about 6–8 weeks later.
- I explain to her what happened and flag chlorhexidine as the suspected trigger.
- Until tested: chlorhexidine-free prep, catheters and lines.
Fatal mistakes
- Antihistamine or steroid before adrenaline.
- Leaving the catheter and chlorhexidine in place.
- Waiting for a rash before treating.
- No allergy referral.
Checked against: Miller 10e · Stoelting 8e · Barash 9e · AHA guidelines: special circumstances of resuscitation (2025)
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