title: Effect of a new heated and humidified breathing circuit with a fluid-warming device on intraoperative core temperature: a prospective randomized study.
abstract: BACKGROUND
  The effect of the Mega Acer kit(@), a new heated and humidified breathing circuit (HHBC) containing a fluid-warming device, was investigated on intraoperative core temperature (T c).
  
  
  METHODS
  A total of 102 patients undergoing elective craniotomies were randomly divided into three groups based on the breathing circuit used: a conventional breathing circuit (group C, n = 34), a Fisher & Paykel HHBC (group F, n = 34), and the Mega (group M, n = 34). From baseline to the end of the surgery, T c and infusion fluid temperature (T f) were recorded at 15-min intervals. If T c became lower than 35.5 °C, a forced-air warmer was used.
  
  
  RESULTS
  Baseline temperatures were 36.7 ± 0.3, 36.6 ± 0.2, and 36.6 ± 0.2 °C in groups C, M, and F, respectively. T c at the end of surgery dropped from baseline values by 1.0 ± 0.4, 0.5 ± 0.5, and 0.8 ± 0.5 °C in groups C, M, and F, respectively. From 60 min of post-induction to the end of surgery, T c was higher in group M than group C (p < 0.05). From 105 min of post-induction to the end of surgery, T c was higher in group M than group F (p < 0.05). The number of patients receiving forced-air warmer and total forced-air warmer using time were significantly lower in group M than groups C and F (p < 0.05). T f was higher in group M than groups C and F throughout the study period (31.0 ± 1.0 vs. 23.5 ± 0.5 and 24.0 ± 0.4 °C; p < 0.01).
  
  
  CONCLUSIONS
  The Mega significantly reduced the drop in intraoperative T c by delivering warm fluids, compared with the other breathing circuits tested.
  
  
  BACKGROUND
  Clinicaltrials.gov identifier: NCT01831843.
authors.affiliation: Department of Anesthesiology and Pain Medicine, Seoul National University Hospital, Seoul National University College of Medicine, 101 Daehangno, Jongno-gu, Seoul, 110-744, Korea.
authors.forename: Eugene
authors.initials: E
authors.lastname: Kim
authors.forename: Sue-Young
authors.initials: SY
authors.lastname: Lee
authors.forename: Young-Jin
authors.initials: YJ
authors.lastname: Lim
authors.forename: Jung-Yoon
authors.initials: JY
authors.lastname: Choi
authors.forename: Young-Tae
authors.initials: YT
authors.lastname: Jeon
authors.forename: Jung-Won
authors.initials: JW
authors.lastname: Hwang
authors.forename: Hee-Pyoung
authors.initials: HP
authors.lastname: Park
mesh_terms: D000328:Adult; D000368:Aged; D001831:Body Temperature / Q000502:physiology*; D001833:Body Temperature Regulation / Q000502:physiology*; D017558:Elective Surgical Procedures / Q000295:instrumentation / Q000379:methods*; D005260:Female; D006358:Hot Temperature; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D016037:Single-Blind Method; D013696:Temperature; D055815:Young Adult