Ellen de Kort

76 Chapter 5 Data extraction Two authors (EdK and NH) extracted details of the included studies independently. The following datawere extracted: use of premedication, used drugs or combination of drugs, scores or parameters determining the decision to proceed with intubation, sedation as parameter to proceedwith intubation, actions undertaken in case of insufficient sedation. Quality appraisal of individual studies Because no studies were found reporting on the usability and validity of scoring systems or other parameters to assess the level of sedation, and we thus only report on common practice as described in the methods sections of the reports, evaluation of the methodological quality and the risk of bias was not relevant. RESULTS Study selection A flowchart of study selection is provided in Figure 1. The initial electronic database search yielded 2597 records, which number was reduced to 1652 after duplicates were removed. One additional record found in reference lists was added. Thus, the titles and abstract of in total 1653 recordswere screened on relevance to the primary and secondary objectives. None of the studies appeared relevant to the primary objective. Regarding the secondary objective, full text was obtained from 75 records and 1578 records were excluded. Of these 75 records, 5were excluded because of language restriction (1 record) or unavailability (4 records). Of the remaining 70 records, full text was read. The studies’ methods sections were screened for information about parameters onwhich the decision to start with intubation was based. Twenty studies provided this information and these were included in the final analysis of our secondary objective. Study characteristics and results of individual studies Table 2 shows the characteristics of the 20 included studies. In 12 studies, the decision to proceed with intubation after the administration of premedication was based on the degree of sedation or relaxation. 7,13-23 Nevertheless, no more than 4 of these 12 studies used an objective scoring system. 13-16 In one other of the 12 studies, disappearance of the eyelash reflex was considered an indicator of hypnosis and therefore as the criterion to start with intubation. 21 In the control group, loss of muscle tone was the criterion to start with intubation. 21 The methods section did not describe, however, how muscle relaxation was rated. In the remaining 7 studies that based the start of the intubation on the degree of sedation and/or relaxation, it was not clear if sedation and/or relaxation were rated either in an objective or a rather subjective way. 7,17-20,22,23 In 8 of the 12 studies,