THE USE OF COUNTERCURRENT HEAT-EXCHANGERS DIMINISHES ACCIDENTAL HYPOTHERMIA DURING ABDOMINAL AORTIC-ANEURYSM SURGERY

Background: Perioperative hypothermia is common and likely contributes to morbidity, but the efficacy of prophylactic fluid warming has hard ly been analyzed systematically. We tested the hypothesis that the use of an infusion/blood warmer, based on the principle of countercurrent heat exchange, reduces incidence and degree of severe hypothermia fol lowing aortic surgery. Methods: In a prospective randomized investigat ion of patients (n=50) undergoing elective abdominal aortic aneurysm s urgery, all fluids/blood products (approx. 3500 ml) administered intra operatively were infused either (n=25) via countercurrent-like heat ex changers (Hotline(TM) Level 1 Technologies Inc.) or without (n=25) tak ing special precautions (infusions stored at 21 degrees C, blood produ cts heated to 37 degrees C in a water bath). Anaesthesia was standardi zed using a thiopentone, fentanyl, vecuronium induction sequence, and maintained by isoflurane in N2O/O-2. Results: The perioperative decrea se of oesophageal temperature (-0.35 degrees C+/-0.4) in the group man aged with heat exchangers was significantly smaller (P<0.0001) than in the control group (-1.5 degrees C+/-0.54), and oesophageal temperatur e at the end of surgery was considerably higher (35.1 degrees C+/-0.45 vs. 34.2 degrees C+/-0.7; P<0.0001). Furthermore, while postoperative hypothermia below 34.5 degrees C was observed in 16 patients (inciden ce: 64%) of the control group, it occurred in only 2 patients (inciden ce: 8%) managed with heat exchangers (P<0.001). Conclusions: The effic acy of fluid/blood warmers has hitherto only been evaluated in bench t ests. Our results demonstrate that the use of heat exchangers alone, w hile not completely preventing hypothermia, markedly reduces the incid ence of severe perioperative hypothermia, and lessens its degree durin g abdominal aortic aneurysm surgery. (C) Acta Anaesthesiologica Scandi navica 40 (1996)