The required sample size for a RCT to test the impact of an interven tion eg

The required sample size for a rct to test the impact

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The required sample size for a RCT to test the impact of an interven- tion ( e.g. , brain function monitor) on the incidence of intraoperative awareness is invariably large. The Task Force also recognizes that, with low-incidence data, a difference in the recording of one or two cases of intraoperative awareness can affect the statistical significance of study findings. Limiting the study to patient subgroups thought to have a higher risk for intraoperative awareness ( e.g. , cardiac surgery, cesarean delivery, emergency trauma surgery) may allow for a smaller sample size and provide useful information regarding these subgroups. However, the Task Force recognizes that the generalizability of these findings to the larger population of general anesthesia patients may be limited. Consensus-based Evidence Consensus was obtained from multiple sources, including (1) survey opinion from consultants who were selected based on their knowledge or expertise in intraoperative awareness, (2) survey opinions from a randomly selected sample of active members of the ASA, (3) testimony from attendees of three open forums held at national anesthesia meet- ings, (4) Internet commentary, and (5) Task Force opinion and inter- pretation. The survey rate of return was 60% (n 57 of 95) for consultants and 30% (n 151/500) for the ASA membership. Survey results are presented in the text of the document and in tables 1 and 2. Ninety-one percent of the consultants and 72% of the ASA members indicated that they had personally used a brain function device in the past. Fifty-seven percent of the consultants indicated that they make use in their current practice of a brain function device always (11.1%), frequently (20.4%), or sometimes (25.9%). Thirty-six percent of the ASA members indicated that they make use in their current practice of a brain function device always (6.0%), frequently (13.4%), or sometimes (16.8%). The consultants were also asked to indicate which, if any, of the evidence linkages would change their clinical practices if the Advisory was instituted. The rate of return was 18% (n 17 of 95). The percent of responding consultants expecting no change associated with each linkage were as follows: preoperative evaluation—82%; informing pa- tients of the possibility of intraoperative awareness—65%; check an- esthesia delivery systems—94%; prophylactic use of benzodiazepines as coenesthetics—100%; use of clinical techniques to monitor for intraoperative awareness—94%; use of conventional monitoring sys- tems to monitor for intraoperative awareness—100%; use of brain function monitors to monitor for intraoperative awareness—59%; in- traoperative use of benzodiazepines for unexpected consciousness— 100%; use of a structured interview for patients who report recall of intraoperative events—41%; use of a questionnaire for patients who report recall of intraoperative events—53%; and counseling for pa- tients who report recall of intraoperative events—76%. Seventy-one percent of the respondents indicated that the Advisory would have no effect on the amount of time spent on a typical case. Four respondents
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