Reliability of pulse oximetry at four different attachment sites in immobilized white rhinoceros (Ceratotherium simum).

Objectives: To determine the reliability of peripheral oxygen haemoglobin saturation (SpO ₂ ), measured by a Nonin PalmSAT 2500A pulse oximeter with 2000T transflectance probes at four attachment sites (third eyelid, cheek, rectum and tail), by comparing these measurements to arterial oxygen haemoglobin saturation (SaO ₂ ), measured by an AVOXimeter 4000 co-oximeter reference method in immobilized white rhinoceros (Ceratotherium simum).
Study Design: Randomized crossover study.
Animals: A convenience sample of eight wild-caught male white rhinoceros.
Methods: White rhinoceros were immobilized with etorphine (0.0026 ± 0.0002 mg kg ^-1 , mean ± standard deviation) intramuscularly, after which the pinna was aseptically prepared for arterial blood sample collection, and four pulse oximeters with transflectance probes were fixed securely to their attachment sites (third eyelid, cheek, rectum and tail). At 30 minutes following recumbency resulting from etorphine administration, the animals were given either butorphanol (0.026 ± 0.0001 mg kg ^-1 ) or an equivalent volume of saline intravenously. At 60 minutes following recumbency, insufflated oxygen (15 L minute ^-1 flow rate) was provided intranasally. In total, the SpO ₂ paired measurements from the third eyelid (n = 80), cheek (n = 67), rectum (n = 59) and tail (n = 76) were compared with near-simultaneous SaO ₂ measurements using Bland-Altman to assess bias (accuracy), precision, and the area root mean squares (ARMS) method.
Results: Compared with SaO ₂ , SpO ₂ measurements from the third eyelid were reliable (i.e., accurate and precise) above an SaO ₂ range of 70% (bias = 1, precision = 3, ARMS = 3). However, SpO ₂ measurements from the cheek, rectum and tail were unreliable (i.e., inaccurate or imprecise).
Conclusions and Clinical Relevance: A Nonin PalmSAT pulse oximeter with a transflectance probe inserted into the space between the third eyelid and the sclera provided reliable SpO ₂ measurements when SaO ₂ was > 70%, in immobilized white rhinoceros.
(Copyright © 2022 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia. Published by Elsevier Ltd. All rights reserved.)