Title: Pulse Oximetry as a Potential Screening Tool for Lower Extremity Arterial Disease in Asymptomatic Patients With Diabetes Mellitus
Authors: Parameswaran G, Brand K, Dolan J
Source: Arch Intern Med. 2005; 165:442-446
PODIATRIC RELEVANCE:
For podiatrists, the diagnosis and prompt treatment of lower extremity arterial disease (LEAD) is crucial. Misdiagnosis can result in ulcerations, infection, gangrene, amputation, and in some cases death.
METHODS:
This article compared the accuracy of pulse oximetry, ankle-brachial index (ABI), and the combination of the two to diagnose LEAD in consecutive outpatients with type 2 diabetes who had no symptoms of LEAD. Exclusions were age younger than 40 years, known LEAD, or typical symptoms of LEAD. Fifty-seven patients were enrolled. All patients had (1) ABI measurement; (2) pulse oximetry to measure Sao2 of their index fingers and big toes in the supine position and at 12-in elevation; and (3) Doppler waveform analysis of the lower extremity arteries. The ABI was considered abnormal if it was less than 0.9. Pulse oximetry of the toes was considered abnormal if the Sao2 was more than 2% lower from the finger or on 12-in elevation of the foot. The combination was considered positive if either the ABI or pulse oximetry was positive for LEAD and negative if both were negative. We defined LEAD as monophasic waveforms on exam.
RESULTS:
31% had LEAD. Pulse oximetry had a sensitivity of 77% (95% confidence interval [CI], 61%-88%) and a specificity of 97% (95% CI, 91%-99%); ABI had a sensitivity of 63% (95% CI, 46%-77%) and a specificity of 97% (95% CI, 91%-99%). Positive likelihood ratios were 30 (95% CI, 7.6-121) for pulse oximetry and 24.8 (95% CI, 6.2-99.8) for ABI; negative likelihood ratios were 0.23 (95% CI, 0.12-0.43) for pulse oximetry and 0.38 (95% CI, 0.25-0.59) for ABI. For the combination, sensitivity was 86% (95% CI, 71%-94%) and specificity was 92% (95% CI, 84%-96%).
COMMENTS:
The study concludes that pulse oximetry of the toes is as accurate as ABI to screen for LEAD in patients with type 2 diabetes. Its sensitivity and specificity were found to be similar to ABI and the combination of the two tests increases sensitivity. Pulse oximeters are readily available, noninvasive, and easy to use.
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Disclaimer:
Scientific Abstract Monthly postings are submitted by podiatric surgical residents. The ideas presented are not the opinions of the American College of Foot and Ankle Surgeons (ACFAS), nor are they presented as facts. ACFAS presents this information without any warranty of any kind, expressed or implied, and is not liable for its accuracy nor for any loss or damage caused by the user's reliance on information obtained in these areas.