Avaliaçäo do arco palmar pelo oxímetro de pulso: estudo comparativo com o método ultrassônico de Doppler / Evaluation of the palmar arch perfusion by pulse oximetry: a comparative study with the ultrasonic Doppler method

Background and Objectives - Assessment of adequate perfusion of the palmar arch is important before cannulations or punctures of the radial artery. The objective of this study was to compare two methods of assessment of such perfusion: Doppler and pulse oximetry (photospectrometry). Methods - The study was performed in forty upper extremities of volunteers, with age varying from 21 to 38 years, physical status ASA I. Blood flow was assessed simultaneously with a ultrasonic Doppler placed between the 3rd and 4th metacarpals and with a pulse oximeter placed on the thumb. The radial and the ulnar arteries were compressed manually on the wrist to interrupt blood flow. Time for initial response to blood flow restoration with both methods were registered flollowing release of ulnar artery compression. Subsequently, the same prosedure was performed for the radial artery. Results - Mean response time with oximetry was significantly longer as compared to the Doppler method. The response time with oximetry was 3.25 s +- 1.45 for the radial artery and 3.38 s +- 1.98 for the ulnar artery. The response time as detected by the ultrasonic Doppler occured in the first second for both arteries. Conclusions - Both methods can be used for the evaluation of the palmar arch blood flow. Pulse oximetry, being a very simple tschnique, is a valuable option. It should be taken into a account, however, that the response time to blood flow with this technique is slightly longer than that observed with the Doppler