Laryngeal injuries and intubating conditions with or without muscular relaxation: an equivalence study

Abstract

Purpose:The need for muscular relaxation to improve intubating conditions and to reduce the incidence of laryngeal morbidity is still controversial. The aim of this study was to determine the incidence of symptomatic laryngeal injuries (SLI) and of acceptable intubating conditions (including both good and excellent conditions), both with and without cisatracurium during induction of anesthesia, along with moderate doses of remifentanil and propofol. Methods:In this prospective, randomized double-blind equivalence trial, the intubating conditions were compared in 130 ASA I or II female patients. All subjects received remifentanil 2 µg·kg -1 iv and propofol 2.5 mg·kg -1 iv, with either cisatracurium 0.15 mg·kg -1 iv (group Cisatracturium), or saline (group Placebo). Tracheal intubating conditions were assessed with the Copenhagen Score. A systematic screening for postoperative hoarseness and sore throat was performed 24 and 48 hr after anesthesia, followed by a nasofibroscopic examination when laryngeal symptoms persisted at 48 hr.Results: Twenty-four hr after anesthesia, the incidence of postoperative hoarseness and sore throat in the Cisatracurium and Placebo groups was 26.5% and 21.5%, respectively, and 48 hr after anesthesia, the incidence was 7.8% and 6.1%, respectively (P = 0.32 and P = 0.50 between groups, respectively). In the clinically evaluable population, the incidence of SLI, assessed at 48 hr by nasofibroscopy, was equivalent in both groups, 1.6% vs 1.5% in group Placebo and group Cisatracurium, respectively (P < 0.001 for equivalence test), as was the occurrence of acceptable intubating conditions (95.4% vs 100%, P < 0.05 for equivalence test). However, the occurrence of excellent intubating conditions was more frequent in group Cisatracurium than in group Placebo (P = 0.0003). Conclusion:Following induction of anesthesia with propofol and moderate-dose remifentanil, cisatracurium did not confer a higher rate of good-to-excellent conditions for tracheal intubation, nor did muscle relaxation with cisatracurium decrease the rate of SLI after tracheal intubation.

GlideScope® Tracheal Intubation with and without Muscle Relaxation: A Prospective, Randomized Clinical Trial

“…This higher dose of propofol has likely contributed to the equal success rate of tracheal intubation and TTI in both groups by relaxing the oropharyngeal and laryngeal muscles enough to perform laryngoscopy and to pass the ETT. This is consistent with a previous study that indicates that increasing doses of propofol improve intubating conditions [12]. Furthermore, the vocal cords were open in all patients in both groups upon initial GVL laryngoscopy.…”

“…So far studies examining GLS tracheal intubation have only been undertaken in anesthetized-paralyzed patients [1,2,15,16]. Based on these previous studies [11][12][13] and according to our own clinical experience, we hypothesized that the rate of success of the GVL tracheal intubation should be similar between patients with or without muscle relaxation.…”

Tracheal intubation: optimal conditions, vocal cord damage, and allergy

“…In 1994, a group of experts met in Denmark to propose a standardization of many aspects of the studies on NMBDs, including intubating conditions. The recommendations of this group were published in 1996, 1 and the intubating scoring system the experts proposed has since been adopted by virtually all investigators, including Bouvet et al 3 The initial recommendations were updated at a meeting held in Stockholm in 2005 and were published last year. 2 Unfortunately, the updated recommendations relating to intubating conditions lack the clarity and detail of the original edition; therefore, it appears preferable to adhere to the previous scoring system for future studies.…”

“…In many studies, such as the study completed by Bouvet et al, 3 excellent and good scores are pooled into an "acceptable" category, while a poor score qualifies as "unacceptable". Thus, the boundary between acceptable and unacceptable conditions is somewhat blurred and may be assessor-dependent.…”

“…4 Recently, poor conditions have been associated with complaints of hoarseness and sore throat in the postoperative period, with documentation of laryngeal injuries. 5 Given the evidence presented by Bouvet et al 3 and considering previous studies, should we be more concerned about paralyzing our patients or damaging their vocal cords?…”