The use of cricoid pressure (Sellick maneuver) during rapid sequence induction (RSI) of anesthesia remains controversial in the absence of a large randomized trial.OBJECTIVE To test the hypothesis that the incidence of pulmonary aspiration is not increased when cricoid pressure is not performed.DESIGN, SETTING, AND PARTICIPANTS Randomized, double-blind, noninferiority trial conducted in 10 academic centers. Patients undergoing anesthesia with RSI were enrolled from February 2014 until February 2017 and followed up for 28 days or until hospital discharge (last follow-up, February 8, 2017).
INTERVENTIONSPatients were assigned to a cricoid pressure (Sellick group) or a sham procedure group.MAIN OUTCOMES AND MEASURES Primary end point was the incidence of pulmonary aspiration (at the glottis level during laryngoscopy or by tracheal aspiration after intubation). It was hypothesized that the sham procedure would not be inferior to the cricoid pressure. The secondary end points were related to pulmonary aspiration, difficult tracheal intubation, and traumatic complications owing to the tracheal intubation or cricoid pressure.
RESULTSOf 3472 patients randomized, mean (SD) age was 51 (19) years and 1777 (51%) were men. The primary end point, pulmonary aspiration, occurred in 10 patients (0.6%) in the Sellick group and in 9 patients (0.5%) in the sham group. The upper limit of the 1-sided 95% CI of relative risk was 2.00, exceeding 1.50, failing to demonstrate noninferiority (P = .14). The risk difference was −0.06% (2-sided 95% CI, −0.57 to 0.42) in the intent-to-treat population and −0.06% (2-sided 95% CI, −0.56 to 0.43) in the per protocol population. Secondary end points were not significantly different among the 2 groups (pneumonia, length of stay, and mortality), although the comparison of the Cormack and Lehane grade (Grades 3 and 4, 10% vs 5%; P <.001) and the longer intubation time (Intubation time >30 seconds, 47% vs 40%; P <.001) suggest an increased difficulty of tracheal intubation in the Sellick group.CONCLUSIONS AND RELEVANCE This large randomized clinical trial performed in patients undergoing anesthesia with RSI failed to demonstrate the noninferiority of the sham procedure in preventing pulmonary aspiration. Further studies are required in pregnant women and outside the operating room.
Substantial agreement exists among experts regarding many strong recommendations for the best care of patients with difficult intubation and extubation in adult anaesthesia.
Nucleosomes prevent the recognition of TATA promoter elements by the basal transcriptional machinery in the absence of induction. However, while Saccharomyces cerevisiae histones H3 and H4 contain N‐terminal regions involved in the activation and repression of GAL1 and in the expression of heterochromatin‐like regions, the sequences involved in repressing basal transcription have not yet been identified. Here, we describe the mapping of new N‐terminal domains, in all four core histones (H2A, H2B, H3 and H4), required for the repression of basal, uninduced transcription. Basal transcription was monitored by the use of a GAL1 promoter‐URA3 reporter construct whose uninduced activity can be detected through cellular sensitivity to the drug, 5‐fluoroorotic acid. We have found for each histone that the N‐terminal sequences repressing basal activity are in a short region adjacent to the structured alpha‐helical core. Analysis of minichromosome DNA topology demonstrates that the basal domains are required for the proper folding of DNA around the chromosomal particle. Deletion of the basal domain at each histone significantly decreases plasmid superhelical density, which probably reflects a release of DNA from the constraints of the nucleosome into the linker region. This provides a means by which basal factors may recognize otherwise repressed regulatory elements.
Computer-assisted models using complex interaction between variables enable an accurate prediction of difficult tracheal intubation with a low proportion of patients in the inconclusive zone. An external validation of the model is now required.
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