A study of worker isoflurane exposure levels in Australian veterinary workplaces

Isoflurane is commonly used in veterinary clinics to anesthetize patients and has known acute and chronic health effects. Exposure to isoflurane should be kept as low as reasonably achievable, to minimize the risk of potential health impacts on workers. This study aimed to evaluate the effectiveness of recommended hazard controls for the management of isoflurane exposure to veterinary staff performing regular anesthesia procedures in equine and small animal settings. Isoflurane exposures were assessed via personal passive sampling using a gas and vapor monitor. It was found that when commonly recommended controls are utilized, including active scavenging systems, leak testing circuitry before use, using a cuffed endotracheal tube, avoiding chamber or mask inductions, and recovering the patient on pure oxygen before disconnection from anesthetic circuitry, worker exposures were below the lowest international Occupational Exposure Standard (OEL) of 2 ppm, in both an equine and small animal setting, with exposures in the equine clinic results having an estimated arithmetic mean of 0.52 ppm (GSD = 1.52) and exposures in the small animal clinics results having an estimated arithmetic mean of 0.34 ppm (GSD = 2.06). Results indicate that additional hazard controls could reduce exposures further and include limiting the total minutes of exposure to isoflurane, delivering the lowest effective isoflurane % to the patient, minimizing the number of times vaporizers are refilled during a work shift, and ensuring that surgery room ventilation is maximized.