Evaluation of waste isoflurane gas exposure during rodent surgery in an Australian university

Abstract

Biomedical researchers use of inhalational anesthetics has increased in recent years. Use of isoflurane as an inhalational anesthetic may result in human exposure to waste anesthetic gas. Potential health effects from exposure include genotoxic and hepatotoxic effects with some evidence of teratogenic and reproductive effects. Research suggests that exposure to waste anesthetic gas within human hospital settings has improved substantially but exposures to biomedical researchers and veterinarians still requires improvement. A number of biomedical research facilities are located at The University of Queensland, Australia, where researchers and animal handlers are potentially exposed to waste isoflurane gas. There is limited published data on the exposures received by biomedical researchers performing routine procedures. This project aimed to assess isoflurane exposure received during routine rodent anesthetic protocols performed at the university. Atmospheric concentrations of isoflurane were assessed via two methods-personal active gas sampling using sorbent tubes and direct readings using infrared spectroscopy. Total procedure and isoflurane exposure times ranged from 135-268 min. Personal sorbent tube sampling detected isoflurane levels from below detectable limits (<0.01 ppm) to a Time Weighted Average for the task (TWA-Task) of 6.20 ppm (0.73 ± 9.13). Participants were not exposed to isoflurane outside of the sampling period during the remainder of the workday. TWA-8 hr adjusted levels ranged from below the limit of detection to 1.76 ppm isoflurane (0.69 ppm ± 0.61 ppm). The infrared spectroscopy readings taken in the breathing zone of participants ranged from 0.1-68 ppm. Results indicate that if adequately controlled through good room ventilation, effective active gas scavenging and well constructed anesthetic equipment, waste anesthetic exposures are minimal. However, where industry standards are not met exposures may occur, including some high peak exposures.

Measurement of anesthetic pollution in veterinary operating rooms for small animals

“…In a study conducted on experimental animals (rodents) anesthetized with isoflurane in a research laboratory, low residual anesthetic concentrations were observed, since the operating room was complying to Australian regulations, with appropriate ventilation and an effective gas exhaustion system and modern model of anesthesia machine, resulting in minimal exposure to anesthetics. 20 In a recent publication, research reports were reviewed retrospectively to evaluate isoflurane exposure in rooms used to perform surgical procedures in animals (primate, swine, and rodent) and in operating rooms where humans underwent surgery at the US National Institutes of Health. 21 Measurements were performed in operating rooms with a laminar flow system that produced 17 air changes per hour without recirculation and whose anesthesia machine also had a scavenging system connected to the central system of exhaustion of the hospital, with suctioning flow of 45 L.min -1 .…”

“…There are some articles in the scientific literature discussing anesthetic pollution in veterinary surgical centers, but all were performed in developed countries and with different objectives. 14 , 16 , 17 , 18 , 19 , 20 , 21 …”

Refinement of anesthetic choice in procedures preceding psychopharmacological studies

“…On the other hand, the needed of equipment for inhalant anesthetic administration enhances the cost and reduces convenience of anesthesia. Further, the waste anesthetic gas leakage may be a occupational risk for researchers (Todd et al 2013;Johnstone et al 2017). From these raised points, it is patent that several factors must be taken into account for the choice of general anesthetic in each experimental design.…”

Intravenous propofol, ketamine (ketofol) and rocuronium after sevoflurane induction provides long lasting anesthesia in ventilated rats

“…With the increasing availability of volatile anesthesia in rodents and apparent benefits compared to injectable anesthetics [ 15 , 16 ], there is an immediate need to describe methods providing safe and reliable use. However, conventional small animal ventilators can lead to high consumptions of volatile anesthetics and room air pollution when appropriate scavenger systems are missing [ 17 , 18 ]. Therefore, maintenance of anesthesia over several hours using volatile anesthetics may be inconvenient and results in unnecessary prolonged exposure of staff.…”