Partial pressure of end-tidal CO2 sampled via an intranasal catheter as a substitute for partial pressure of arterial CO2 in dogs

Authors

  • D. Pang BVSc,

    1. Department of Clinical Sciences, Faculté de médecine vétérinaire, Université de Montréal, Québec, Canada, and
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  • J. Hethey,

    1. Department of Small Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Canada
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  • N. A. Caulkett DVM, MVetSc, DACVA,

    1. Department of Small Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Canada
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  • T. Duke BVetMed, DVA, DACVA, DECVA

    1. Department of Small Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Canada
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Address correspondence and reprint requests to:
Dr. Tanya Duke, Department Small Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, 52 Campus Dr., Saskatoon, SK, Canada, S7N 5B4.
E-mail: tanya.duke@usask.ca

Abstract

Objective: To demonstrate correlation and clinical usefulness of the partial pressure of end-tidal CO2 (ETCO2) measurement by nasal catheter placement in sedated dogs with and without concurrent nasal oxygen administration as a substitute for partial pressure of arterial CO2 (PaCO2).

Design: Prospective, cross-over trial.

Setting: University of Saskatchewan veterinary research laboratory.

Animals: Six cross-breed dogs with a mean (±SD) weight of 29.1±4.03 kg.

Interventions: All dogs were sedated with 5 μg/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 ETCO2 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 ETCO2 measurement underestimated (negative bias) the PaCO2 by −2.20 mmHg with limits of agreement (95% confidence interval) of −5.79, 1.39 mmHg. In the group receiving oxygen supplementation, ETCO2 measurement underestimated (negative bias) the PaCO2 by −2.46 mmHg with limits of agreement (95% confidence interval) of −8.42, 3.50 mmHg.

Conclusions: The results of this study demonstrate that ETCO2 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.

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