Relation between end-tidal and arterial carbon dioxide partial pressure during general anaesthesia with spontaneous breathing and controlled ventilation in dogs - An experimental study

Abstract

The aim of the study was to assess the value of capnometry during anaesthesia with spontaneous breathing and controlled ventilation in dogs free of pulmonary disease. Ten beagle dogs were included in the study. End-tidal carbon dioxide (ETCO2), minute respiratory volume (ME), heart rate and arterial blood gases were measured. The correlation between ETCO 2 and PaCO2 was positive and statistically significant in both types of general anaesthesia. ME was negatively correlated with ETCO 2 and PaCO2, although this was statistically significant only during controlled ventilation. The PaCO2 - ETCO2 gradient increased significantly comparing to the awake state during the experiment with controlled ventilation indicating haemodynamic depression as a consequence of deepening of anaesthesia. The results of the study demonstrated that capnometry can noninvasively provide valuable information about changes in minute respiratory volume and arterial blood gases during general anaesthesia with spontaneous breathing and controlled ventilation in dogs free of pulmonary disease. Comparable literature data imply that capnometry is equally useful in other animal species.