title: The effect of electrically heated humidifier on the body temperature and blood loss in spinal surgery under general anesthesia.
abstract: BACKGROUND
  General anesthesia often produces some degree of hypothermia and hypothermia causes much more blood loss during surgery than normothermia. Electrically heated humidifiers (EHHs) have been used for patients under general anesthesia and in the intensive care unit. However, the benefits of the EHH have not been widely reported in the literature.
  
  
  METHODS
  Patients scheduled for posterior lumbar spine fusion, were randomly assigned to a mechanically ventilated with EHH circuit group or to a conventional respiratory circuit group. Their tympanic membrane temperature was monitored every 30 min after induction up to 180 min, and perioperative blood losses, transfusion requirements during surgery, and other complications were noted.
  
  
  RESULTS
  Patients in the control group (n = 40) showed a lower mean body temperature at all times than immediately after induction, while the EHH group (n = 40) showed a lower body temperature from 60 minute after induction comparing to the initial temperature. Furthermore, patients in the EHH group had a higher mean body temperature than patients in the control group during surgery (35.9 ± 0.4 vs 35.4 ± 0.5, P < 0.001). Mean intraoperative blood loss (9.75 ± 5.4 vs 7.48 ± 3.9, P = 0.035) and transfusion requirements (57.5% vs 25%, P = 0.006) were significantly less in the EHH group, but postoperative blood loss, duration of hospitalization, and other complications were not significantly different in the two study groups.
  
  
  CONCLUSIONS
  The use of an electrically heated humidifier did not prevent a body temperature drop under general anesthesia. However, it helped maintain body temperature and was associated less blood loss and transfusion requirement during surgery.
authors.affiliation: Department of Anesthesiology and Pain Medicine, National Health Insurance Corporation Ilsan Hospital, Goyang, Korea.
authors.forename: Hyun Kyu
authors.initials: HK
authors.lastname: Lee
authors.forename: Yeon-Hee
authors.initials: YH
authors.lastname: Jang
authors.forename: Kwan-Woong
authors.initials: KW
authors.lastname: Choi
authors.forename: Jae Ho
authors.initials: JH
authors.lastname: Lee