Evaluation of pulse oximeter probes and probe placement in healthy dogs

Placement of two different pulse oximeter probes, a finger (f) probe and a multisite (s) probe, was evaluated in six healthy, anesthetized beagles. Concurrent arterial blood gas values were compared to determine the most consistent (repeatable) and accurate (compared to calculated hemoglobin saturations) pulse oximeter probe and probe placement sites for subsequent use in awake dogs. Hemoglobin oxygen saturation was determined from arterial blood gas analysis (SaO2) and by pulse oximetry (SpO2) at full hemoglobin saturation (mean, 99.5% SaO2) and at moderate desaturation (mean, 92.9% SaO2). Each probe was evaluated with three independent readings at seven different body sites (Achilles, ear, flank, lip, tail, toe, and tongue). Values for SpO2 obtained with the s probe demonstrated a significant correlation with SaO2 values (p = 0.014, R = 0.712) compared to the SpO2 values obtained with the f probe (p = 0.108). The best probe placement sites for the clip-on probes in this study were on the lip and tongue using the s probe; however, the ear, tail, and toe may be acceptable sites in awake dogs using a probe which maintains good contact across these vascular beds.