The effectiveness of reducing endotracheal cuff pressure after retractor placement to decrease postoperative laryngeal dysfunction in anterior cervical surgery: a meta-analysis

OBJECTIVE The authors sought to determine if a consensus could be reached regarding the effectiveness of endotracheal tube cuff pressure (ETTCP) reduction after retractor placement in reducing postoperative laryngeal dysfunction after anterior cervical fusion surgery. METHODS A literature search of MEDLINE (PubMed), EMBASE, Cochrane Central, Google Scholar, and Scopus databases was performed. Quantitative analysis was performed on data from articles comparing groups of patients with either reduced or unadjusted ETTCP after retractor placement in the context of anterior cervical surgery. The incidence and severity of postoperative recurrent laryngeal nerve palsy (RLNP), dysphagia, and dysphonia were compared at several postsurgical time points, ranging from 24 hours to 3 months. Heterogeneity was assessed using the chi-square test, I² statistics, and inverted funnel plots. A random-effects model was used to provide a conservative estimate of the level of effect. RESULTS Nine studies (7 randomized, 1 prospective, and 1 retrospective) were included in the analysis. A total of 1671 patients were included (1073 [64.2%] in the reduced ETTCP group and 598 [35.8%] in the unadjusted ETTCP group). In the reduced ETTCP group, the severity of dysphagia, measured by the Bazaz-Yoo system in 3 randomized studies at 24 hours and at 4-8 weeks, was significantly lower (24 hours [standardized mean difference: -1.83, p = 0.04] and 4-8 weeks [standardized mean difference: -0.40, p = 0.05]). At 24 hours, the odds of developing dysphonia were significantly lower (OR 0.51, p = 0.002). The odds of dysphagia (24 hours: OR 0.77, p = 0.24; 1 week: OR 0.70, p = 0.47; 12 weeks: OR 0.58, p = 0.20) were lower, although not significantly, in the reduced ETTCP group. The odds of a patient having RLNP were significantly lower at all time points (24 hours: OR 0.38, p = 0.01; 12 weeks: OR 0.26, p = 0.03) when 3 randomized and 2 observational studies were analyzed. A subgroup analysis using only randomized studies demonstrated a similar trend in odds of having RLNP, yet without statistical significance (24 hours: OR 0.79, p = 0.60). All other statistically significant findings persisted with removal of any observational data. CONCLUSIONS Based on the current best available evidence, reduction of ETTCP after retractor placement in anterior cervical surgery may be a protective measure to decrease the severity of dysphagia and the odds of developing RLNP or dysphonia.