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Updated: Dec 28, 2025
Non-invasive Assessment of Microvascular and Endothelial Function
Published on: January 29, 2013
The modified Allen test and a novel objective screening algorithm for hand collateral circulation using differential
Ahmed Elwali1, Zahra Moussavi1,2
1Biomedical Engineering Program, University of Manitoba, Winnipeg, Canada.
Hand-ischemia and artery-thrombosis are serious complications of hand artery cannulation/grafting. Screening the patency of hand arteries reduces the complications. Modified Allen Test (MAT), Barbeau's test, and Doppler/Duplex-ultrasonic test screen hand arterial patency. Each of them, however, either lacks objectivity, requires subject cooperation, or is not readily available in operating rooms. In this pilot study, we aim to provide a novel, objective, reliable, and inexpensive alternative using differential photo-plethysmography (PPG) measurement, and an artery selection algorithm. For 11 participants, MAT was executed, and PPG measurements of the thumb and little fingers were recorded for left and right hands separately. For each hand, four evaluations were conducted, then fed into the artery selection algorithm. Our proposed procedure has shown congruent results with the anatomy of blood circulation. It identified two arteries in two participants causing >50% blood reduction in the hand due to their occlusion. It also showed an elevated risk of accessing an artery in another 8 participants. Once the results of this study are confirmed in larger samples, the proposed procedure/algorithm may provide many indicators of the hand blood circulation, the effect of an artery occlusion on the hand, and a recommendation for selecting the best artery to access with the lowest possible complications.
Hand-ischemia and artery-thrombosis are serious complications of hand artery cannulation/grafting. Screening the patency of hand arteries reduces the complications. Modified Allen Test (MAT), Barbeau's test, and Doppler/Duplex-ultrasonic test screen hand arterial patency. Each of them, however, either lacks objectivity, requires subject cooperation, or is not readily available in operating rooms. In this pilot study, we aim to provide a novel, objective, reliable, and inexpensive alternative using differential photo-plethysmography (PPG) measurement, and an artery selection algorithm. For 11 participants, MAT was executed, and PPG measurements of the thumb and little fingers were recorded for left and right hands separately. For each hand, four evaluations were conducted, then fed into the artery selection algorithm. Our proposed procedure has shown congruent results with the anatomy of blood circulation. It identified two arteries in two participants causing >50% blood reduction in the hand due to their occlusion. It also showed an elevated risk of accessing an artery in another 8 participants. Once the results of this study are confirmed in larger samples, the proposed procedure/algorithm may provide many indicators of the hand blood circulation, the effect of an artery occlusion on the hand, and a recommendation for selecting the best artery to access with the lowest possible complications.
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