title: Intraoperative core temperature patterns, transfusion requirement, and hospital duration in patients warmed with forced air.
abstract: BACKGROUND
  Core temperature patterns in patients warmed with forced air remain poorly characterized. Also unknown is the extent to which transient and mild intraoperative hypothermia contributes to adverse outcomes in broad populations.
  
  
  METHODS
  We evaluated esophageal (core) temperatures in 58,814 adults having surgery lasting >60 min who were warmed with forced air. Independent associations between hypothermic exposure and transfusion requirement and duration of hospitalization were evaluated.
  
  
  RESULTS
  In every percentile subgroup, core temperature decreased during the first hour and subsequently increased. The mean lowest core temperature during the first hour was 35.7 ± 0.6°C. Sixty-four percent of the patients reached a core temperature threshold of <36°C 45 min after induction; 29% reached a core temperature threshold of <35.5°C. Nearly half the patients had continuous core temperatures <36°C for more than an hour, and 20% of the patients were <35.5°C for more than an hour. Twenty percent of patients had continuous core temperatures <36°C for more than 2 h, and 8% of the patients were below 35.5°C for more than 2 h. Hypothermia was independently associated with both transfusions and duration of hospitalization, although the prolongation of hospitalization was small.
  
  
  CONCLUSIONS
  Even in actively warmed patients, hypothermia is routine during the first hour of anesthesia. Thereafter, average core temperatures progressively increase. Nonetheless, intraoperative hypothermia was common, and often prolonged. Hypothermia was associated with increased transfusion requirement, which is consistent with numerous randomized trials.
authors.affiliation: From the Department of Outcomes Research, Cleveland Clinic, Cleveland, Ohio (Z.S., H.H., D.I.S., K.P., L.S., A.K.); Department of Quantitative Health Sciences and Outcomes Research, Cleveland Clinic, Cleveland, Ohio (J.E.D., D.Y.); and Anesthesiology Institute, Cleveland Clinic, Cleveland, Ohio (A.F.D., V.S.). Current affiliations: Anesthesiology and Perioperative Medicine, Georgia Regent University, Augusta, Georgia (Z.S.); and Department of Anesthesiology, Faculty of Medicine, Chiang Mai University, Chiangmai, Thailand (K.P.).
authors.forename: Zhuo
authors.initials: Z
authors.lastname: Sun
authors.forename: Hooman
authors.initials: H
authors.lastname: Honar
authors.forename: Daniel I
authors.initials: DI
authors.lastname: Sessler
authors.forename: Jarrod E
authors.initials: JE
authors.lastname: Dalton
authors.forename: Dongsheng
authors.initials: D
authors.lastname: Yang
authors.forename: Krit
authors.initials: K
authors.lastname: Panjasawatwong
authors.forename: Armin F
authors.initials: AF
authors.lastname: Deroee
authors.forename: Vafi
authors.initials: V
authors.lastname: Salmasi
authors.forename: Leif
authors.initials: L
authors.lastname: Saager
authors.forename: Andrea
authors.initials: A
authors.lastname: Kurz
mesh_terms: D000328:Adult; D000388:Air; D001803:Blood Transfusion / Q000706:statistics & numerical data*; D001831:Body Temperature / Q000502:physiology*; D017707:Erythrocyte Transfusion / Q000379:methods; D004947:Esophagus / Q000502:physiology; D005260:Female; D006801:Humans; D007035:Hypothermia / Q000628:therapy; D007432:Intraoperative Period; D007902:Length of Stay; D008297:Male; D017694:Rewarming / Q000379:methods*