Comparison of Transmittance and Reflectance Pulse Oximetry in Anesthetized Dogs.

Jan Nixdorff,Rene Dörfelt,Katrin Hartmann,Yury Zablotski

doi:10.3389/fvets.2021.643966

Jan Nixdorff, Rene Dörfelt + Show 2 more

Open Access

https://doi.org/10.3389/fvets.2021.643966

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Abstract

Objectives: The tongue is the standard site for placement of a pulse oximeter probe but is difficult to access during certain procedures such as dental and ophthalmic procedures and computerized tomography of the head. The aim of this study was to evaluate the performance of a new-generation reflectance pulse oximeter using the tail and tibia as sites for probe attachment.Materials and Methods: A total of 100 client-owned dogs that underwent anesthesia for various reasons were premedicated with butorphanol (n = 50; 0.2 mg/kg; group BUT) or butorphanol and dexmedetomidine (n = 50; 5 μg/kg; group DEX), administered intravenously. Anesthesia was induced with propofol and maintained with sevoflurane. A transmittance pulse oximeter probe was placed on the tongue and served as the reference standard. A reflectance probe was randomly placed on the tail base or the proximal tibia, and the position changed after testing. Signals from three consecutive measurements were obtained at each position. Failure was defined as “no signal,” “low signal,” or a pulse difference >10/min compared with the ECG heart rate. Data were analyzed using chi-square test, Wilcoxon matched-pair signed-rank test, and Bland-Altman analysis. P < 0.05 was considered significant.Results: In both groups (BUT and DEX), failure rate was higher when the tibia and tail were used as probe sites compared with the tongue. In both groups, the failure rate was higher for the tibia than for the tail. Dexmedetomidine-induced vasoconstriction increased failure rate at all probe positions.Clinical Significance: The tail base, but not the tibia, is an acceptable position for reflectance pulse oximeter probes in dogs. The tongue remains the probe site of choice, if accessible.

Highlights

Pulse oximetry is considered a standard tool for monitoring veterinary patients during anesthesia
Values were only included if measurements for both positions were available and analyzed as paired values. n, number of measurements; tongue, transmittance pulse oximeter probe placed on the tongue; tail, reflectance pulse oximeter probe placed on the ventral tail base; tibia, transmittance pulse oximeter probe placed on the medial aspect of the proximal tibia; SpO2, oxygen saturation measured by pulse oximeter; BUT, premedication butorphanol 0.2 mg/kg IV; DEX, premedication dexmedetomidine 5 μg/kg + butorphanol 0.2 mg/kg IV; m, median
Pulse rate values that differed from the ECG by >10 beats per minute were excluded. n, number of measurements; tongue, transmittance pulse oximeter probe placed on the tongue; tail, reflectance pulse oximeter probe placed on the ventral tail base; tibia, transmittance pulse oximeter probe placed on the medial aspect of the proximal tibia; HR, heart rate; PR, pulse rate; BUT, premedication butorphanol 0.2 mg/kg IV; DEX, premedication dexmedetomidine 5 μg/kg + butorphanol 0.2 mg/kg IV; m, median

Summary

Introduction

Pulse oximetry is considered a standard tool for monitoring veterinary patients during anesthesia. Transmittance pulse oximetry is the most commonly used method and involves emission of red and infrared light, which passes through the tissues from one side of the Reflectance Pulse Oximetry in Dogs probe to a receiver on the opposite side. The standard site for probe placement using transmittance pulse oximetry is the tongue in dogs. A plausible solution is the use of reflectance pulse oximetry, which is commonly applied in human medicine at the chest wall, the foot sole, and the forehead as probe placement sites [3,4,5,6,7]. The probe emits infrared and red light, which passes through the tissues, is reflected by the underlying bone, and detected at the level of the light-emitting electrodes. Reflectance pulse oximetry has been used empirically in dogs with the medial aspect of the proximal tibia and the ventral part of the tail base used as probe placement sites

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