Blood flow measurement in PTFE grafts.

ABSTRACT

In vascular surgery peroperative control of the result of reconstruction is essential. PTFE-grafts have been known to be "resistant" to flow registration with electromagnetic flowmetry because of the electrical isolation. Similarly, intraoperative Doppler registration has been impossible because of the attenuation of the ultrasound in the graft wall. The leading disturbances are obviously caused by air in the graft material and are not caused by the material itself. By squeezing the graft carefully between the thumb and forefinger, blood slowly penetrates the wall colouring it red. The squeezing is performed intermittently to avoid occlusion of the graft. Excellent flow registration is obtained after less than 2 min squeezing of the thin walled graft, while at least 5 min squeezing is necessary to obtain signals from thick walled grafts. To obtain satisfactory ultrasound signals more squeezing is necessary.