Capture of isoflurane from anaesthetised dogs and cats following methadone, medetomidine and ketamine administration

BACKGROUND: Volatile anaesthetic agents contribute to climate change, and reducing this impact is a commendable ambition. We evaluated the efficiency of a veterinary capture device for isoflurane (VET-can/VET-dock, SageTech Veterinary) in anaesthetised cats and dogs. METHODS: Purposeful sampling was used to recruit enough animals undergoing isoflurane general anaesthesia to fill one VET-can to at least 95% capacity. The vaporiser and VET-can were weighed pre- and post-anaesthesia to determine in vivo mass transfer (MT) of isoflurane and water. The primary outcomes were capture efficiency (isoflurane delivered: desorbed, %) and in vivo MT. The secondary outcomes were associations between MT and patient characteristics and anaesthesia variables. RESULTS: Thirty anaesthetics (21 cats and nine dogs) were required to fill the VET-can to capacity. The overall capture efficiency was 81% isoflurane with 4% water' as it's the isoflurane capture efficiency that matters here and the water capture explains the difference in overall efficiency and MT. LIMITATIONS: Interchangeable use of sidestream and mainstream capnography resulted in a difference in times to end-tidal isoflurane 0%. CONCLUSIONS: e for each 20-minute anaesthetic period, approximately the equivalent of 13 miles driven in an average UK car.