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

Capture efficiency was 81%. The device prevented a mean release of 3.2 kgCO2e for each 20-minute anaesthetic period, approximately the equivalent of 13 miles driven in an average UK car.