Use of infra-red carbon dioxide analysis during general anaesthesia in the horse

The carbon dioxide content of respiratory gases may be monitored by the use of an infra-red carbon dioxide analyser. The technique allows continuous and non-invasive recording of important information concerning the ventilatory, circulatory and metabolic states of the anaesthetised horse. Some of the monitoring capabilities of a carbon dioxide analyser (capnograph) are reviewed with illustrations from cases anaesthetised in the authors' clinic. Technical faults in the anaesthetic apparatus and the connections with the "patient" could be readily detected and emergency situations immediately recognised and treated without delay. Use of the apparatus allowed refinement of the anaesthetic technique and greatly augmented the safety of general anaesthesia.