1. Chlorhexidine Tomaz Garcez Consultant Immunology

2. What we already know (1)
Chlorhexidine is widely used in healthcare and the community (see appendix in report)
A “hidden allergen” responsible for a significant number of cases of perioperative anaphylaxis
Geographical variation
Under-recognition
Differential practice / use of decontamination / testing for allergy
Highly effective antiseptic

3. What we already know (2) Uses include:
Skin decontamination
Lubricating gels
Coated catheters (CVC)
Dental
Commonly there are features of a prior reaction in those subsequently confirmed with allergy
Investigation for allergy not standardised (timing or tests)
Positive tests to other potential culprits reported

4. Key Findings (1) 3rd of the “big four” – 18 cases (9%)
16 males
6 urology surgery; 3 cardiac; 3 orthopaedics
0.78 events per 100,000 exposures (possible overestimate)
1 fatal case
Not investigated by specific IgE to chlorhexidine

5. Exposure routes
Number
Time to onset & grade
Skin for cannula 10
Skin for neuraxial blockade 7
Skin for surgical site 4
≈ 1 hour; grade 3
Coated CVC 6
< 5 minutes; grade 4
Urethral gel 11
None where only reported exposure was skin preparation for cannulation

6. Clinical features

7. Key Findings (2)
Often not suspected (only in 28% of cases) by anaesthetist
3 potentially avoidable cases
1 reported prior chlorhexidine allergy
1 reported prior perioperative allergy that was not investigated
1 NAP6 confirmed chlorhexidine allergy case experienced subsequent anaphylaxis to chlorhexidine in 2nd procedure
Chlorhexidine coated central lines not always removed (2 of 6 CVC related cases)

8. Key Findings (3) 16 patients had dynamic / raised tryptase
Testing for chlorhexidine was frequently omitted in allergy clinics
Testing does not always follow recommendations

9. Test modalities
Number
Positive*
Skin prick testing only 7 6
Skin prick testing and IgE 3
3 (both tests)
Skin prick testing, intradermal testing and IgE
2 (all tests) 1 (IDT & IgE)
IgE only 2
Intradermal testing only 1
Intradermal testing and IgE
1 (both tests)
Only 7 cases had more than one test as is recommended
In 3 cases more than one trigger identified on testing

10. Key Recommendations National: Institutional: Individual:
Prominent labelling (MHRA & manufacturers)
Institutional:
Alternatives should be available
All cases should be tested for chlorhexidine with at least 2 modalities of test; and all potential culprits should be tested
Individual:
Improved awareness of chlorhexidine and allergy history taking
Chlorhexidine coated CVCs should be removed when anaphylaxis occurs following insertion

11. Thank you