Background and objective: Pulse oximetry of the toes has been suggested in the screening of peripheral arterial disease. We studied the uselfuness of pulse oximetry in detection of type 2 diabetic patients with carotid atherosclerosis.
Subjects and methods: 105 patients with type 2 diabetes mellitus (DM) without previous clinical peripheral arterial disease were enrolled. All patients had (1) ankle-brachial index (ABI) measurement, (2) pulse oximetry to measure SaO(2) of their index fingers and big toes in the supine position and at elevated 30cm and (3) a carotid ultrasound [carotid artery intima-media thickness (IMT) and carotid plaques (CP) measurements]. The ABI was considered abnormal when it was <0.9 and when the pulse oximetry showed a decrease in SaO(2) of >2% of the finger compared to foot or to 30cm foot elevation.
Results: 60 patients were men (age of 62+/-7 years, HbA(1c) of 6.9+/-1.0); 58.1% had CP. There were no differences in anthropometric and biochemical results between patients with or without CP. The ABI was <0.9 in 49% and 25% of patients with and without CP, respectively. Neither were there differences in pulse oximetry in patients with CP or in those with ABI <0.9. The IMT did not change in relation to pulse oximetry, but it was higher in patients with CP and with ABI <0.9 than in patients without alterations. These results were independent of the presence of previous clinical macroangiopathy.
Conclusion: Pulse oximetry is not a useful screening method of carotid atherosclerosis in type 2 DM.