[Photoplethysmography evaluation of collateral blood flow before puncture of the dorsalis pedis artery].

Prior to cannulation of the dorsalis pedis artery the collateral circulation through the plantar arch should be examined to evaluate the consequence of an occlusion of this artery. Since the performance of the Allen's test is impossible for assessment of the plantar arch, another suitable technique has to be chosen. We selected the photoelectric plethysmography. Toe pulses were recorded with photoelectric plethysmography in 20 neurosurgical patients. The pulse amplitudes were measured before and during successive compression of the dorsalis pedis and the posterior tibial artery. Obvious decrease or absence of the pulse wave during compression of the dorsalis pedis artery is indicating an inadequate collateral circulation and cannulation of this artery seems not to be safe. In our study this occurred in 4 of 32 examined feet (12.5 percent). The photoelectric plethysmography has proved to be a simple and accurate means for assessment of collateral circulation.