Use of pocket pulse oximeters for detecting peripheral arterial disease in patients with diabetes mellitus

Recent Aims: New diagnostic methods are needed to detect peripheral arterial disease easier than using the ankle-brachial index measured by Doppler devices. We investigated whether the use of pocket pulse oximeters could meet sensitivity and specificity criteria as screening method to detect significant peripheral arterial perfusion deficits. Methods: We measured oxygen saturation (SaO2) at index fingers and great toes (on horizontal and elevated 30°) by a pocket pulse oximeter in 250 subjects with diabetes mellitus attending the outpatient clinic. A finger-to-toe SaO2 gradient greater than 2% was considered abnormal. Ankle-brachial index was measured by a hand held Doppler device. Peripheral arterial disease was defined as an ankle-brachial index less than 0.9. Results: A total of 1392 (93%) valid SaO2 readings were obtained. Twenty-seven (11%) patients were excluded due to not having measurable SaO2 finger-to-toe gradients. A total of 223 patients were analyzed. Peripheral arterial disease was detected in 47 (21%) patients. A finger-to-toe SaO2 gradient greater than 2% had sensitivity 42.6% (95% CI 30.0% - 55.3%), specificity 79.1% (95% CI 75.7% - 82.6%), positive predictive value 35.7% (95% CI 25.2% - 46.4%), negative predictive value 83.4% (95% CI 79.8 - 87.1), positive likelihood ratio 2.03 (95% CI 1.23 - 3.17) and negative likelihood ratio 0.73 (95% CI 0.54 - 0.93) to detect peripheral arterial disease. The area under the receiving operating characteristic curve was 0.69 (95% CI 0.62 - 0.77). Conclusion: Pocket pulse oximeters showed insufficient sensitivity as screening method for detecting peripheral arterial disease in patients with diabetes mellitus.