No abstract

Objective: To demonstrate correlation and clinical usefulness of the partial pressure of end-tidal CO 2 (ETCO 2 ) measurement by nasal catheter placement in sedated dogs with and without concurrent nasal oxygen administration as a substitute for partial pressure of arterial CO 2 (PaCO 2 ). Design: Prospective, cross-over trial. Setting: University of Saskatchewan veterinary research laboratory. Animals: Six cross-breed dogs with a mean ( AE SD) weight of 29.1 AE 4.03 kg. Interventions: All dogs were sedated with 5 mg/kg medetomidine intravenously (IV) and an arterial catheter was placed in a dorsal pedal artery for removal of blood for gas analysis. A nasal catheter was placed in the ventral meatus and connected to a capnometer for ETCO 2 measurements in all dogs. Dogs receiving supplemental nasal oxygen had a second nasal catheter placed in the contralateral naris. Measurements and main results: In the group without nasal oxygen supplementation, the ETCO 2 measurement underestimated (negative bias) the PaCO 2 by À 2.20 mmHg with limits of agreement (95% confidence interval) of À 5.79, 1.39 mmHg. In the group receiving oxygen supplementation, ETCO 2 measurement underestimated (negative bias) the PaCO 2 by À 2.46 mmHg with limits of agreement (95% confidence interval) of À 8.42, 3.50 mmHg. Conclusions:The results of this study demonstrate that ETCO 2 monitoring via a nasal catheter provides a clinically acceptable substitute to arterial blood gas analysis as a means of monitoring ventilation in healthy, sedated dogs. The limits of agreement were within acceptable limits with and without concurrent insufflation of oxygen.