Comparison of Pulse Oximetry and Handheld Doppler for Assessing Digital Perfusion

The utility of pulse oximetry for evaluating the perfusion of an injured digit is not well established. The goal of our study was to compare the use of a handheld Doppler to the use of pulse oximetry to determine perfusion in the digits of healthy volunteers.

Fifteen healthy volunteers participated in our study. All digits of both hands were assessed, for a total of 150 digits. Baseline measurements were performed for both the Doppler and pulse oximeter. Then, a pulse oximeter was placed on each digit for 1 minute and the recordings taken at the end of the minute. A Penrose drain was used to occlude each digit. Once perfusion was absent, the pulse oximeter was placed onto the digit. Pulse oximeter readings were recorded for 1 minute and then averaged over that time. For the first five patients, a hinge type sensor was used and for the second group of 10 patients, a rubber sleeve type sensor was used.

The mean baseline pulse oximeter reading averaged an oxygen saturation of 98.9% (range: 96% to 100%). For the hinge type pulse oximeter sensor, no readout was obtained for the unperfused digits, thus making the results binary. Using the rubber sleeve type pulse oximeter sensor, the mean unperfused readings dropped to an oxygen saturation of 85.0% (range: 71% to 98%). The difference between baseline and the rubber sleeve sensor was significant. The mean drop in pulse oximetry oxygen saturation reading between baseline and occluded digits was 15%.

Our study supports the use of pulse oximetry in the assessment of fingertip perfusion, specifically for confirming that a digit is well perfused. Depending on the model of pulse oximeter used, results may be binary (signal or no signal) or show a decrease in reading compared to a perfused digit. Although pulse oximetry cannot be utilized as a sole diagnostic study for vascular injury, it can be a useful adjuvant. Statement of Significance: The evaluation of an injured finger includes the assessment of vascular status. Handheld Doppler in conjunction with physical exam can be used to diagnose vascular injury, but this is often unavailable or unfamiliar to the medical staff initially evaluating the patient. This study analyzes the use of pulse oximetry in the evaluation of poorly perfused digits. Pulse oximeters are simple, inexpensive, readily available, and familiar to all medical personnel.