Side to Side Probe Position improves Accuracy of Pulse Oximeter Readings in the Presence of Nail Polish.

Abstract

Background: Pulse oximetry is an invaluable monitor within and outside the operating theatre. Its accuracy may be affected by nail polish. With the probe in the standard top to bottom position, previous results have been inconsistent. This study investigated the accuracy of peripheral oxygen saturation (SpO2) readings with the probe in the side to side position in the presence of nail polish. 

Materials and Methods: Seventy healthy female volunteers had their fingers numbered from left to right (left little finger = 1 & right little finger = 10). Alternate fingers were painted with red, blue, purple, brown and black nail colours (experimental). The corresponding finger on the other hand served as control. SpO2 readings were obtained in the top to bottom and side to side probe positions.

Results: In the top to bottom position, SpO2 values were recorded for all fingers painted red (100%). The mean SpO2 for all experimental fingers differed significantly from their corresponding controls (p=0.028 for red and p<0.001 for others). No oximetry readings were observed with Purple, Blue, Brown and Black nail polishes in 4.3%, 32.9%, 40% and 61.4% of volunteers respectively. In the side to side position, no missing values were observed and no significant difference was obtained between the experimental fingers and controls (p>0.05). 

Conclusion: Placing the probe in the side to side position obviated inaccuracies obtained in the presence of nail polish. This position may be adopted in emergent surgeries when time may not be available to remove the nail polish. 

Keywords: pulse oximeter, nail polish, probe position.