Effect of lingual gauze swab placement on pulse oximeter readings in anaesthetised dogs and cats.

This study aimed to evaluate the effect of lingual gauze swab placement on pulse oximeter readings in anaesthetised dogs and cats. Following anaesthetic induction, the following pulse oximeter probe configurations were performed: no gauze swab (control), placement of a gauze swab between the tongue and the probe, placement of different thicknesses of gauze swab, placement of red cotton fabric, placement of a sheet of white paper and placement of the probe and gauze swab on different locations on the tongue. Oxygen saturation (SpO) and peripheral perfusion index (PI) were recorded. Placement of a gauze swab between the pulse oximeter probe and the tongue in anaesthetised dogs and cats resulted in significantly higher SpO values compared with the control group. In dogs, PI values were significantly higher than the control in all groups except the quarter thickness swab group. In cats, PI was significantly higher in the double thickness swab and white paper groups compared with the control. Cats had significantly higher SpO and lower PI values than dogs. The authors propose that increased contact pressure is responsible for significantly higher SpO and PI readings with the use of a lingual gauze swab resulting from changes in transmural pressure and arterial compliance.