Cm. Muth et al., THE USE OF COUNTERCURRENT HEAT-EXCHANGERS DIMINISHES ACCIDENTAL HYPOTHERMIA DURING ABDOMINAL AORTIC-ANEURYSM SURGERY, Acta anaesthesiologica Scandinavica, 40(10), 1996, pp. 1197-1202
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)