title: Incidence of Connected Consciousness after Tracheal Intubation: A Prospective, International, Multicenter Cohort Study of the Isolated Forearm Technique.
abstract: The isolated forearm technique allows assessment of consciousness of the external world (connected consciousness) through a verbal command to move the hand (of a tourniquet-isolated arm) during intended general anesthesia. Previous isolated forearm technique data suggest that the incidence of connected consciousness may approach 37% after a noxious stimulus. The authors conducted an international, multicenter, pragmatic study to establish the incidence of isolated forearm technique responsiveness after intubation in routine practice.
  
  
  
  Two hundred sixty adult patients were recruited at six sites into a prospective cohort study of the isolated forearm technique after intubation. Demographic, anesthetic, and intubation data, plus postoperative questionnaires, were collected. Univariate statistics, followed by bivariate logistic regression models for age plus variable, were conducted.
  
  
  
  The incidence of isolated forearm technique responsiveness after intubation was 4.6% (12/260); 5 of 12 responders reported pain through a second hand squeeze. Responders were younger than nonresponders (39 ± 17 vs. 51 ± 16 yr old; P = 0.01) with more frequent signs of sympathetic activation (50% vs. 2.4%; P = 0.03). No participant had explicit recall of intraoperative events when questioned after surgery (n = 253). Across groups, depth of anesthesia monitoring values showed a wide range; however, values were higher for responders before (54 ± 20 vs. 42 ± 14; P = 0.02) and after (52 ± 16 vs. 43 ± 16; P = 0.02) intubation. In patients not receiving total intravenous anesthesia, exposure to volatile anesthetics before intubation reduced the odds of responding (odds ratio, 0.2 [0.1 to 0.8]; P = 0.02) after adjustment for age.
  
  
  
  Intraoperative connected consciousness occurred frequently, although the rate is up to 10-times lower than anticipated. This should be considered a conservative estimate of intraoperative connected consciousness.
authors.affiliation: From the Department of Anesthesiology, University of Wisconsin-Madison, Madison, Wisconsin (R.D.S., A.R., C.B., A.H., R.M.B.); Department of Anesthesia, Rambam Healthcare Campus, Haifa, Israel (A.R.); Department of Anesthesiology and Critical Care, Houston Methodist Hospital, Houston, Texas (R.M.B.); Department of Anaesthesia, Waikato Clinical School, University of Auckland, Hamilton, New Zealand (A.G., J.W., J.S.); Department of Anesthesiology; University Hospital RWTH Aachen, Aachen, Germany (A.S., R.R., M.C.); Department of Anesthesia and Intensive Care Medicine, CHU University Hospital of Liège, Liège, Belgium (A.D., G.T., V.B.); University Department of Anesthesia and Intensive Care Medicine, CHR Citadelle and CHU University Hospital of Liège, Liège, Belgium (A.D., G.T., V.B.); Department of Anesthesiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands, (S.T., S.M., A.A.); and Department of Anesthesiology, University of Michigan, Ann Arbor, Michigan (P.E.V., H.F., G.A.M.).
authors.forename: Robert D
authors.initials: RD
authors.lastname: Sanders
authors.forename: Amy
authors.initials: A
authors.lastname: Gaskell
authors.forename: Aeyal
authors.initials: A
authors.lastname: Raz
authors.forename: Joel
authors.initials: J
authors.lastname: Winders
authors.forename: Ana
authors.initials: A
authors.lastname: Stevanovic
authors.forename: Rolf
authors.initials: R
authors.lastname: Rossaint
authors.forename: Christina
authors.initials: C
authors.lastname: Boncyk
authors.forename: Aline
authors.initials: A
authors.lastname: Defresne
authors.forename: Gabriel
authors.initials: G
authors.lastname: Tran
authors.forename: Seth
authors.initials: S
authors.lastname: Tasbihgou
authors.forename: Sascha
authors.initials: S
authors.lastname: Meier
authors.forename: Phillip E
authors.initials: PE
authors.lastname: Vlisides
authors.forename: Hussein
authors.initials: H
authors.lastname: Fardous
authors.forename: Aaron
authors.initials: A
authors.lastname: Hess
authors.forename: Rebecca M
authors.initials: RM
authors.lastname: Bauer
authors.forename: Anthony
authors.initials: A
authors.lastname: Absalom
authors.forename: George A
authors.initials: GA
authors.lastname: Mashour
authors.forename: Vincent
authors.initials: V
authors.lastname: Bonhomme
authors.forename: Mark
authors.initials: M
authors.lastname: Coburn
authors.forename: Jamie
authors.initials: J
authors.lastname: Sleigh
mesh_terms: D000328:Adult; D000368:Aged; D000768:Anesthesia, General; D015331:Cohort Studies; D003243:Consciousness / Q000187:drug effects*; D005260:Female; D005542:Forearm / Q000502:physiology*; D006225:Hand; D006801:Humans; D015994:Incidence; D038622:Internationality; D007442:Intubation, Intratracheal; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000295:instrumentation / Q000379:methods*; D011446:Prospective Studies; D014111:Tourniquets; D055815:Young Adult