Prewarming non-inflatable cuff laryngeal mask for mechanical ventilation: A systematic review and meta-analysis with trial sequential analysis

Non-inflatable cuff laryngeal masks are generally composed of thermoplastic material. The thermoplastic nature of the non-inflatable cuff will become soft and match the laryngeal anatomy better as it reaches body temperature after intubation. This meta-analysis aims to evaluate the clinical validity of prewarming non-inflatable cuff laryngeal mask before insertion. METHODS: We searched PubMed, Cochrane Library, Embase, Web of Science, Ovid Medline, CNKI, Wan Fang Database and VIP Database to find randomized controlled trials (RCTs) researching the clinical validity of prewarming non-inflatable cuff laryngeal mask. The retrieval time is up to June 2022. Articles published in the English and Chinese languages were considered. Quality assessment was conducted with the Cochrane Collaboration’s tool and GRADE (Grading of Recommendations Assessment, Development and Evaluation) method. Subgroup analyses and trial sequential analysis (TSA) were performed to control the risk of random errors. Publication bias was assessed by funnel plots and Egger’s regression test. The outcomes included sealing pressure immediately after successful ventilation, the first-attempt intubation success rate and the incidence of postoperative pharyngeal pain. RESULTS: Eight RCTs evaluating 683 patients were identified. Pooled results showed that compared to the control group, prewarming non-inflatable cuff laryngeal mask provided a higher sealing pressure immediately after successful ventilation (mean difference: 1.73 cm H(2)O; 95% confidence interval [CI]: 0.95-2.52; P < .0001; I(2) = 16; high quality), higher first-attempt intubation success rate (risk ratio [RR]: 1.05; 95% CI: 1.01-1.09; P = .01; I(2) = 26%; high quality, number needed to treat [NNT] = 22 [95% CI 12.5-100]) and lower incidence of postoperative pharyngeal pain (RR: 0.59, 95% CI: 0.46-0.75; P < .0001; I(2) = 0; high quality, NNT = 6 [95% CI 4.17-9.09]). The results were confirmed by TSA. CONCLUSION: Prewarming non-inflatable cuff laryngeal mask could provide better mechanical ventilation efficiency with higher sealing pressure, a higher first-attempt intubation success rate and a lower incidence of postoperative pharyngeal pain. TRIAL REGISTRATION NUMBER: PROSPERO CRD42021245350