Residual glutaraldehyde levels in fiberoptic endoscopes: measurement and implications for patient toxicity

Most gastroenterology societies recommend glutaraldehyde for fiberoptic endoscope disinfection. However, glutaraldehyde toxicity has been suspected in patients examined with endoscopes disinfected with this compound. The aim of our study was to determine the residual levels of glutaraldehyde in fiberoptic endoscopes after either manual or automatic disinfection and to evaluate the extent of toxicity. Furthermore, the procedures for disinfection currently performed by the department were compared with the new French guidelines. We used both manual and automatic disinfection procedures and flushed sterile distilled water through the lumens of endoscopes before use. Residual glutaraldehyde levels were determined using liquid chromatography coupled to spectrophotometric detection. In a total of 92 measurements it was found that residual glutaraldehyde levels were higher and more variable after manual disinfection (< 0.2-159.5 mg/L) than after automatic disinfection (< 0.2-6.3 mg/L). We conclude that local procedures for disinfection need to be improved to conform to the new French guidelines. Since thresholds for the toxic dose of glutaraldehyde and international norms for levels of residual glutaraldehyde in equipment have not been defined, additional studies combining accurate measurements in fiberoptic endoscopes and clinical observations of endoscopy patients will be required to draw more definitive conclusions.