With the increasing utilization of the radial artery as a graft in CABG a reliable evaluation of the integrity of the palmar arch in each patient, is important in order to prevent classically vascular complications of the hand, one uses the Allen test, which is based on a subjective evaluation of the colour change of the hand, when the radial and ulnar pulse are pressed and, therefore, more prone to misinterpretations. For an objective evaluation, we propose this test, analyzing perfusion through pulse oxymetry, a simple method easily available in the operating room. Purpose: The authors present a new proposal to evaluate perfusion and integrity of the palmar arch by pulse oxymetry, comparing information obtained through method with the one obtained through the Allen test. Method: Fifty radial and 50 ulnar arteries from 25 patients in prone position were studied. Patients were 45 years or over, 19 males and 6 females, in stable cardiorespiratory conditions, and free of known peripheral vascular disease in the upper limbs. The oxymeter used was from Ohmeda, and the portable Doppler, with continuous flow from Medical Electronics. At first, the probe was put over the index finger of each hand sequentially observing the saturation level which we called initial. The Doppler was used for the radial and ulnar pulses. The Allen test was performed in each hand, digitally compressing both arteries, with the oxymeter in the second finger, observing the disappearance of the pulse wave. The ulnar artery was then released, causing the return of the pulse wave and obtaining the final saturation. In 96% of cases, there was a drop in saturation ranging from 0 to 2 points. The Doppler probe was located distally to the compression of the radial artery, showing no flow in it. Results: The Allen test proved to be satisfactory (return of colour to the hand in 5 seconds or less) in 35 procedures (70%), and unsatisfactory in 15 of them (30%). The oxymetry was normal in 49 procedures (98%), with an important saturation drop in just one case (2%), in which the Allen test was unsatisfactory. Conclusions: We observed a rather meaningful difference between the results from the Allen test and those from oxymetry, leading one to question the validity of the Allen test regarding its efficacy, since it is a subjective method compared to an objective one (oxymetry). Therefore, we could not be using the radial artery as a graft in 26% of the cases evaluated through the Allen test.
Oximetry; Hand; Radial artery
