Chlorhexidine Tomaz Garcez - PowerPoint Presentation

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Chlorhexidine

Tomaz GarcezConsultant Immunology

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 anaphylaxisGeographical variationUnder-recognitionDifferential practice / use of decontamination / testing for allergyHighly effective antiseptic

What we already know (2)

Uses include:Skin decontaminationLubricating gelsCoated catheters (CVC)DentalCommonly there are features of a prior reaction in those subsequently confirmed with allergyInvestigation for allergy not standardised (timing or tests)Positive tests to other potential culprits reported

Key Findings (1)3rd of the “big four” – 18 cases (9%)

16 males6 urology surgery; 3 cardiac; 3 orthopaedics0.78 events per 100,000 exposures (possible overestimate)1 fatal caseNot investigated by specific IgE to chlorhexidine

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 CVC6< 5 minutes; grade 4Urethral gel11

None where only reported exposure was skin preparation for cannulation

Clinical features

Key Findings (2)

Often not suspected (only in 28% of cases) by anaesthetist3 potentially avoidable cases1 reported prior chlorhexidine allergy1 reported prior perioperative allergy that was not investigated 1 NAP6 confirmed chlorhexidine allergy case experienced subsequent anaphylaxis to chlorhexidine in 2nd procedureChlorhexidine coated central lines not always removed (2 of 6 CVC related cases)

Key Findings (3)

16 patients had dynamic / raised tryptaseTesting for chlorhexidine was frequently omitted in allergy clinicsTesting does not always follow recommendations

Only 7 cases had more than one test as is recommended

In 3 cases more than one trigger identified on testing

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 3 2 (all tests) 1 (IDT & IgE) IgE only 2 2

Intradermal testing only

1

1

Intradermal testing and IgE

1

1 (both tests)

Key Recommendations

National:Prominent labelling (MHRA & manufacturers)Institutional:Alternatives should be availableAll cases should be tested for chlorhexidine with at least 2 modalities of test; and all potential culprits should be testedIndividual:Improved awareness of chlorhexidine and allergy history takingChlorhexidine coated CVCs should be removed when anaphylaxis occurs following insertion

Thank you