Reducing endotracheal tube cuff pressure (ETTCP) following retractor placement in anterior cervical fusion surgery may be a protective measure to decrease the severity of dysphagia and the odds of developing recurrent laryngeal nerve palsy (RLNP) or dysphonia, according to a recent meta-analysis—the findings of which were published in the Journal of Neurosurgery: Spine by Saikiran Murthy (Albert Einstein College of Medicine and Montefiore Medical Center, New York, USA) et al.
The aim of the meta-analysis was to determine if a consensus could be reached regarding the effectiveness of ETTCP reduction after retractor placement in reducing postoperative laryngeal dysfunction following anterior cervical fusion surgery.
Literature searches of the PubMed, EMBASE, Cochrane Central, Google Scholar and Scopus databases was conducted. 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 RLNP, dysphagia, and dysphonia were compared at various postsurgical time points, ranging from 24 hours to three months. Heterogeneity was assessed using the chi-squared test, I statistics, and inverted funnel plots. A random-effects model was used to provide a conservative estimate of the level of effect.
In all, nine studies—seven randomised, one prospective and one retrospective—were included in the meta-analysis. From these, a total of 1,671 patients were included (1,073 [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 three randomised studies at 24 hours and at four to eight weeks, was significantly lower (24 hours [standardised mean difference −1.83, p=0.04] and four to eight weeks [standardised mean difference −0.40, p=0.05]).
At 24 hours, the odds of developing dysphonia were significantly lower (odds ratio [OR] 0.51, p=0.002). The odds of dysphagia (24 hours: OR 0.77, p=0.24; one week: OR 0.7, 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 three randomised and two observational studies were analysed. A subgroup analysis using only randomised studies demonstrated a similar trend in odds of having RLNP, yet without statistical significance (24 hours: OR 0.79, p=0.60).