Left molar approach improves laryngeal view in patients with simulated limitation of cervical movements

Abstract

Immobilized cervical spine, because of either diseases or stabilizing devices, poses considerable difficulties with endotracheal intubation due to poor laryngoscopic view. The left molar (LM) approach has been shown to be useful in difficult sporadic intubation cases. We evaluated efficacy of this approach of laryngoscopy to improve laryngeal view in patients with simulated limitation of cervical movements. Thirty patients of American Society of Anesthesiologists grade I/II, who were scheduled to undergo routine surgical procedures under general anaesthesia and endotracheal intubation, were studied. A two-piece semi-rigid cervical collar was used to immobilize the cervical spine. Under standardized anaesthesia and neuromuscular blocking agent, conventional laryngoscopy using a curved Macintosh blade was performed and glottic view was recorded with and without optimal external laryngeal manipulation (OELM). Subsequently, in the same subjects the laryngoscope blade was withdrawn and re-inserted through the LM approach and glottic view was recorded with and without OELM followed by tracheal intubation. With the conventional approach, laryngeal view was recorded as grade II in five patients, grade III in 24 patients, and grade IV in one patient. However, with the LM approach, laryngeal view was grade I in 25 patients, grade II in five patients, and grade III or IV in none (P<0.001). Tracheal intubation with the LM approach required the use of a flexible stylet to guide the tube tip into the larynx. The laryngeal view is improved by the LM approach in patients with simulated limited cervical movements with a high success rate of tracheal intubation, but requires orientation for negotiation of the tube through the narrow oropharyngeal space available.