NAP6: Perioperative Anaphylaxis. Anaesthesia, Surgery and Life-threatening Allergic Reactions.

Editors Cook T, Harper N.

National Audit Project, RCOA.2018

Background

• The National Audit Projects aim to gather information on anaesthesia-related topics to help improve care going forward.
• The information is gathered from all NHS hospitals over a period of one year.
• Previous NAP projects have included looking at complications of neuroaxial blocks and accidental awareness.

Aims

• Review the reporting and subsequent investigations for potential anaphylaxis.
• Identify the main causative agents of perioperative anaphylaxis.
• Compare management and subsequent care with current available guidelines.
• Identify correlation between the initial management of perioperative anaphylaxis and subsequent outcomes.

Method

• 1-year data collection period in all UK NHS hospitals, studying every case of life-threatening anaphylaxis during anaesthesia
• Examined incidence, predisposing factors, management and impact of life threatening perioperative anaphylaxis.
• Included national survey of anaesthetist experience and perception and survey of allergy clinics, along with detailed reports of all Grade 3 – 5 perioperative anaphylaxis.
• Cases reviewed by a multi-disciplinary team to aim to reduce bias.
• Management and investigations compared to recognised national guidelines

Results

• > 500 cases reported of grade 3 – 5 with 266 cases suitable for analysis.
• 266 cases of Grade 3-5 anaphylaxis (261 cases excluded).
• Incidence of perioperative anaphylaxis of 1 : 11,752.
• Reporting to local reporting systems occurred in 70% of cases, reporting to the UK regulatory system < 25%
• The identified main culprits:
  1. Antibiotics:
     92/2,469,754 = 1 in 26,845 (95% CI 1 in 21,889 – 1 in 33,301)
  2. NMBAs:
     64/1,220,465 = 1 in 19,070 (95% CI 1 in 14,934 – 1 in 24,762)
  3. Chlorhexidine:
     18/2,298,567 = 1 in 127,698 (95% CI 1 in 80,800 – 1 in >150,000)
  4. Patent blue dye:
     9/61,768 = 1 in 6,863 (95% CI 1 in 3,616 – 1 in 15,009).

NO LATEX identified as a precipitant in this audit

Antibiotics –

• 92 cases – 89% Co-amoxiclav and Teicoplanin – Highest incidence: Teicoplanin (16.4 per 100,000 exposures)
• Of the 10 deaths: 4 were judged to be due to an antibiotic.

Neuromuscular blockers –

• 65 cases of anaphylaxis were triggered by NMBAs
• 25% of all cases and 32% of cases leading to death or cardiac arrest.
• Highest incidence – Suxamethonium (11.1 per 100,000 exposures).

Chlorhexidine –

• Almost 10% of all cases, -third most prevalent cause of anaphylaxis, incidence 0.78 per 100,000 exposures, 1 case fatal.
• Anaphylaxis from chlorhexidine was often delayed, testing for Chlorhexidine was frequently omitted in allergy clinics.

Patent Blue Dye –

• Patent Blue dye: fourth commonest cause of perioperative anaphylaxis reported to NAP6.
• 9 cases of Patent Blue dye anaphylaxis were identified; incidence of 14.6/100,000 administrations (1:6,863) – higher than suxamethonium and one of the highest in NAP6 (second only to Teicoplanin).

Clinical Features

• Presenting features hypotension 46%, bronchospasm 18%, tachycardia 9.8%, oxygen desaturation 4.7%, bradycardia 3%, reduced/absent capnography 2.3%. All patients hypotensive at some point.
• Rash/skin involvement uncommon, 1 episode of front of neck access due to oedema.
• 10 deaths and 40 cardiac arrests.

Management

• All patients were treated promptly in terms of a ‘critical event’
• 25% there was a delay in anaphylaxis treatment.
• > 50 % there was a delay in starting chest compressions (recommendations suggest Systolic BP <50 requires CPR).
• Generally felt insufficient IV Fluid administration and 19% felt inappropriate.
• 70 % required level 3 care, those in ITU stayed 2 days
• Patients who died: older, obese, co-morbidities, on ACE inhibitors.
• Types of arrest bradycardia – > PEA (34), tachycardia – > VF/VT (4), Asystole (2)

Severe Anaphylaxis Incidence  1:313000.

• 10 fatalities (8 direct and 2 indirect)
• 1 patient normal weight – four were overweight, one was obese and four morbidly obese.
• None of the patients who died had a history of atopy or asthma.
• 6 patients taking beta blockers and 6 patients taking ACE inhibitors – 3 taking both, one taking neither.

Conclusions/Recommendations/Discussion Points

• In all cases a consultant/career grade anaesthetist was present
• In just under 50 % – quality of management found to be ‘good’ this was attributed to – delay in adrenaline, poor IVF treatment and delayed/lack of CPR when BP <50 or unrecordable.
• Mortality rate 3.8%.
• Mast cell tryptase levels did not correspond with clinical severity.
• Recommended need to appoint an ‘Anaphylaxis lead’ within the Anaesthetics department.
• Expand allergy clinic services with standardised investigations.
• Treatment and investigation packs should be available perioperatively.
• Vasopressin and glucagon should be available within 10 minutes.
• IV fluids to be given at 20ml/kg and repeated.
• Mast cell trytase – shoul be performed ASAP, 1-2 hours, 24 hours.
• Consent patients for anaphylaxis and provide a letter to patient if episode of anaphylaxis (from the anaesthetist).
• Patients with allergy to beta-lactam and one other antibiotic should have full testing before elective surgery.
• No test dose should be given and preferably antibiotics before induction.
• If NMBA allergy – need to provide a choice for RSI.

 

Summary by Dr C Donovan. Journal Club 21 June 2018.