Patient and staff exposure to glutaraldehyde from KeyMed Auto-Disinfector endoscope washing machine

Activated glutaraldehyde (2%) is the recommended agent for disinfection of endoscopic equipment. Exposure to the disinfectant is associated with side-effects and guidelines have been set to avoid these complications. Endoscope washing machines are used to provide automated high level disinfection of endoscopes as well as reduce exposure to the irritant aldehyde. We report a design fault in an endoscope washing machine which results in patients and staff being exposed to activated glutaraldehyde. The Auto-Disinfector (KeyMed) comprises a washing chamber supplied by three separate reservoirs (detergent, disinfectant, and rinse water) via a common channel. After the first cycle endoscopes are processed using previously used detergent and rinse water. Rinse water glutaraldehyde concentrations were measured in four machines during routine endoscopy lists on at least two occasions and showed a progressive rise in glutaraldehyde concentration up to 0.1% after two to six cycles. This results in staff being exposed to glutaraldehyde present on the processed instrument and the disinfectant being pumped from the internal channels of the endoscope into direct contact with the gastrointestinal mucosa during endoscopy at concentrations of 200-1000 ppm. The present atmospheric limit for glutaraldehyde is 0.2 ppm. Skin and mucosal irritation occur at concentrations of 0.3 ppm and severe synovitis in experimental animals at 100 pm. Tongue swelling and bloody diarrhoea with characteristic mucosal histological changes have been reported in patients exposed to activated glutaraldehyde on inadequately rinsed equipment. To reduce this problem the rinse water should be changed after every cycle and the endoscope should be dried thoroughly before use.