title: The use of countercurrent heat exchangers diminishes accidental hypothermia during abdominal aortic aneurysm surgery.
abstract: BACKGROUND
  Perioperative hypothermia is common and likely contributes to morbidity, but the efficacy of prophylactic fluid warning has hardly 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 following aortic surgery.
  
  
  METHODS
  In a prospective randomized investigation of patients (n = 50) undergoing elective abdominal aortic aneurysm surgery, all fluids/blood products (approx. 3500 ml) administered intraoperatively were infused either (n = 25) via countercurrent-like heat exchangers (Hotline Level 1 Technologies Inc.) or without (n = 25) taking special precautions (infusions stored at 21 degrees C, blood products heated to 37 degrees C in a water bath). Anaesthesia was standardized using a thiopentone, fentanyl, vecuronium induction sequence, and maintained by isoflurane in N2O/O2.
  
  
  RESULTS
  The perioperative decrease of oesophageal temperature (-0.35 degree C +/- 0.4) in the group managed with heat exchangers was significantly smaller (P < 0.0001) than in the control group (-1.5 degrees C +/- 0.54), and oesophageal temperature 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 (incidence: 64%) of the control group, it occurred in only 2 patients (incidence: 8%) managed with heat exchangers (P < 0.001).
  
  
  CONCLUSIONS
  The efficacy of fluid/blood warmers has hitherto only been evaluated in bench tests. Our results demonstrate that the use of heat exchangers alone, while not completely preventing hypothermia, markedly reduces the incidence of severe perioperative hypothermia, and lessens its degree during abdominal aortic aneurysm surgery.
authors.affiliation: Institut für Klinische Anaesthesiologie, Heinrich-Heine-Universität Düsseldorf, Germany.
authors.forename: C M
authors.initials: CM
authors.lastname: Muth
authors.forename: B
authors.initials: B
authors.lastname: Mainzer
authors.forename: J
authors.initials: J
authors.lastname: Peters
mesh_terms: D000368:Aged; D017544:Aortic Aneurysm, Abdominal / Q000601:surgery*; D005260:Female; D006358:Hot Temperature; D006801:Humans; D007035:Hypothermia / Q000517:prevention & control*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies