Measurement of vascular access recirculation unaffected by cardiopulmonaryrecirculation: Evaluation of an ultrasound method

Recently developed devices provide detection of access recirculation (AR) a nd cardiopulmonary recirculation (CPR) by optical, thermal, conducimetrical , and ultrasound methods (USM). We evaluated the last one both in vitro rep roducing AR by a bypass pump and in vivo. in vitro, the USM sensitivity was about 5%. In vivo, the USM was compared with the traditional urea method ( UM) in 69 patients. 8.7% of the cases resulted positive by both UM and USM. One case was USM positive and UM negative. The UM sensitivity threshold wa s 6-10%. The accuracy (in vitro) and the repeatability (in vivo) of the USM were satisfactory. USM clearly distinguished AR from CPR. In conclusion, A R determination by USM, avoiding misleading interferences with CPR, is a ra pid, easy, and noninvasive method to routinely exclude a potential cause of reduced dialytic efficiency.