Laryngeal morbidity after tracheal intubation: the Endoflex® tube compared to conventional endotracheal intubation with stylet

Background Tracheal intubation may cause vocal fold damage. The trial was designed to assess laryngeal morbidity comparing the Endoflex (R) tube with a conventional endotracheal tube with stylet. We hypothesised that laryngeal morbidity within the first 24h after extubation would be lower with the Endoflex tube than with the conventional endotracheal tube with stylet because of less rigidity. Methods This randomised trial included 130 elective surgical patients scheduled for general anaesthesia with endotracheal intubation. Pre- and post-operative assessment of hoarseness, vocal fold pathology, and voice analysis using the Multidimensional Voice Program was performed. Induction of anaesthesia was standardised. After complete neuromuscular paralysis, intubation was done with an Endoflex tube or a conventional endotracheal tube with stylet. Results Post-operative hoarseness was found in 45% with the Endoflex tube and 55% with the endotracheal tube with stylet at 24h after extubation (P=0.44). Post-operative vocal fold injury was present in 23% in the Endoflex tube group and in 36% in the endotracheal tube with stylet group (P=0.13). The increase in shimmer, the voice analysis variable reflecting vocal fold oedema, was 0.5% in the Endoflex tube group and 2.5% in the endotracheal tube with stylet group (P=0.02). Conclusion No significant difference was found in the incidence of hoarseness or vocal fold injury using the Endoflex tube. However, the statistically significant lower increase in the shimmer values in that group implies that the Endoflex may be associated with less laryngeal morbidity.