Incidence of Connected Consciousness after Tracheal Intubation A Prospective, International, Multicenter Cohort Study of the Isolated Forearm Technique

Robert D. Sanders*, Amy Gaskell, Aeyal Raz, Joel Winders, Ana Stevanovic, Rolf Rossaint, Christina Boncyk, Aline Defresne, Gabriel Tran, Seth Tasbihgou, Sascha Meier, Phillip E. Vlisides, Hussein Fardous, Aaron Hess, Rebecca M. Bauer, Anthony Absalom, George A. Mashour, Vincent Bonhomme, Mark Coburn, Jamie Sleigh

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

78 Citations (Scopus)

Abstract

Background: 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.

Methods: 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.

Results: 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.

Conclusions: 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.

Original languageEnglish
Pages (from-to)214-222
Number of pages9
JournalAnesthesiology
Volume126
Issue number2
DOIs
Publication statusPublished - Feb-2017

Keywords

  • BISPECTRAL INDEX
  • GENERAL-ANESTHESIA
  • CESAREAN-SECTION
  • AWARENESS REACTION
  • DEPTH
  • WAKEFULNESS
  • INDUCTION
  • PREDICT

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