Pulse Oximetry As The Potential Screening Tool For Lower Extremity Arterial Disease In Asymptomatic Patients With Diabetes Mellitus

Background: Lower extremity arterial disease (LEAD) is common and under Diagnosed in patients with Diabetes Mellitus (DM). Risk persists even when LEAD is Subclinical. It is an important socio-economical and healthcare problem, due to its High incidence of morbidity, disability and mortality and its related cardiovascular events. Early detection of LEAD, before the onset of symptoms in patient with DM, is desirable and can lead to tighter, better control of risk factors for arterial disease. Present study is an effort to compare for the accuracy of Pulse Oximetry, the Ankle- Brachial index (ABI) and the combination of the two to diagnose LEAD in Asymptomatic type 2 DM patients. Methods: Fifty type 2 DM patients who had no symptoms of LEAD attending OPD and IPD in Dr.B.R.Ambedkar medical college during recent 2 years were enrolled. Exclusions were age <40 years, known LEAD, or typical symptoms of LEAD. All patients had (1) ABI measurement and considered abnormal < 0.9 (2) pulse oximetry to measure SaO₂ of their index fingers and big toes in the supine position and SaO₂ of the toes was considered abnormal if the SaO₂ was more than 2% lower from the finger. The combination was considered positive if either the ABI or pulse oximetry was positive for LEAD and negative if both were negative. And (3) Doppler waveform analysis of the lower extremity arteries used as standard comparison for above tests and defined LEAD as monophasic waveforms. Results: Of our 50 patients (100 legs examined), 31 (31%) had LEAD. Pulse Oximtery has a Sensitivity of 74.14%, Specificity of 97.10%, and Positive predictive value of 92% and Negative predictive value of 89.3%. ABI has a Sensitivity of 60.60%, Specificity of 97.12%, and Positive predictive value of 90.9% and Negative predictive value of 87.9%. Combination has a Sensitivity of 87%,Specificity of 94.20%, and Positive predictive value of 87% and Negative predictive value of 94.20%. Conclusion: Pulse oximetry of the toes seems to be simple and as accurate as ABI to Screen for LEAD in patients with Type 2 Diabetes. Combination of the two tests increases sensitivity.