CONSCIOUSNESS, CONNECTEDNESS AND INTRAOPERATIVE UNRESPONSIVENESS STUDY (CONSCIOUS): A PROSPECTIVE INTERNATIONAL MULTICENTER COHORT STUDY OF THE ISOLATED FOREARM TECHNIQUE FOLLOWING INTUBATION

BACKGROUND: Prior data from the isolated forearm technique (IFT) following noxious stimuli suggest that the incidence of response to command may approach 40% under anesthesia 1,2 . We conducted an international, multicenter, pragmatic study of the IFT to establish the incidence of responsiveness following intubation in current practice (NCT02248623). Methods: Following IRB approval at six sites, 260 adult patients were recruited from six centers into a prospective observational cohort study of the IFT during induction of anesthesia . Univariate comparisons were made with Student’s t­test assuming equal variances, and Pearson’s χ2 test. Bivariate models were constructed using logistic regression . RESULTS: The incidence of IFT responsiveness following intubation was 4 .6% (12/260). Responders were younger than nonresponders ([mean±standard deviation] 39±17 vs . 51±16 years old; p=0 .009) and had a higher incidence of observer rated signs of distress (50% vs . 2 .4%; p=0 .027) with 5 out of 12 responders reporting pain through a second hand squeeze . No subject reported explicit recall of intraoperative events when questioned after surgery (n=253) . Depth of anesthesia monitoring values showed a wide range in both groups; however mean values were higher for responders before (53±19 vs . 42±14; p=0 .032) and after (55±24 vs . 43±16; p=0 .032) intubation . In patients not receiving total intravenous anesthesia, exposure to volatile anesthetics prior to intubation reduced the odds of responding (OR 0 .2 (0 .1 - 0 .8); p=0 .022) following adjustment for age . CONCLUSIONS: An incidence rate of 4 .6% suggests that intraoperative connected consciousness may occur frequently but this rate is lower than predicted from previous studies . Larger studies are required to identify risk factors for, and long-term consequences of, IFT responsiveness. REFERENCES: 1 . Sanders RD, Tononi G, Laureys S, Sleigh JW . Unresponsiveness ≠ Unconsciousness Anesthesiology. 2012;116:946­959. 2 . Schneider G, Wagner K, Reeker W, Hanel F, Werner C, Kochs E. Bispectral Index (BIS) may not predict awareness reaction to intubation in surgical patients . J Neurosurg Anesthesiol . Jan 2002;14(1):7-11