Abstract

 

 

Objectives: We evaluated the newly designed battery-powered McGrath Portable Video Laryngoscope (MVL; model series 5), with a miniaturized video screen mounted on the proximal end of the laryngoscope handle and a disposable laryngoscope blade covering the camera stick, in patients requiring orotracheal intubation and determined whether successful tracheal intubation correlates with conventional laryngoscopic view grading (CLV).

 

Design: Patients with previously experienced difficult conventional tracheal intubation, anatomic features predictive for difficult conventional laryngoscopy (CL) and tracheal intubation, and/or obesity were given preferential enrollment into the study. Therefore, this clinical investigation represents data of a prospective, but non-consecutive observational study.

 

Setting: The study was performed at a community hospital with a reference center for the management of thyroid diseases.

 

Patients: One hundred and twenty patients undergoing elective thyroid surgery were investigated.

 

Operators: The operators (4 staff anesthetists, 3 anesthesia residents, and one qualified anesthesia nurse) were experienced users of video laryngoscopes. They performed MVL-assisted laryngoscopy and tracheal intubation attempts on from 10 to a maximum of 20 (median: 14) patients.

 

Interventions: CLV was performed with a standard Macintosh laryngoscope using gentle lifting force without external laryngeal manipulation: grade 1, visualization of the entire laryngeal aperture; grade 2, visualization of just the posterior portion of the laryngeal aperture; grade 3, visualization of only the arytenoids; grade 4, visualization of only the epiglottis; and grade 5, visualization of just the soft palate. The laryngeal views obtained with the MVL were evaluated using the same technique as for CL and the 5-grade scoring system. MVL-assisted tracheal intubation was attempted when laryngeal structures were visible using the Schroeder directional tracheal tube stylet (DS) for manipulation of the tracheal tube (TT) through the laryngeal aperture.

 

Measurements and Main Results:  Laryngeal views of grade 1 to 4 at CL were obtained in 40, 38, 26, and 16 patients, respectively. The success rate of MVL-assisted tracheal intubation at the first attempt was 97 percent (116/120 patients) with laryngeal views of grade 1 in all of these patients; the causes of primary failures of tracheal intubation were acute loss of battery power in one patient and failed TT advancement during laryngeal passage in 3 patients. Minor problems and difficulties with poor visibility due to fogging of the camera system and TT advancement during laryngeal and/or tracheal passage were encountered in altogether 11 and 13 percent, respectively; there were no problems with impeded blade insertion due to limited mouth opening and/or restricted pharyngeal space, poor visibilty due to the presence of secretions, and impeded TT advancement during oropharyngeal passage. The remaining 4 patients required a second attempt for successful tracheal intubation.

 

Conclusions: Performed by experienced users of video laryngoscopes, the success of MVL-assisted tracheal intubation was not affected by CLV. The MVL together with the DS may be useful for routine and difficult laryngoscopy and tracheal intubation; however, further studies are required to substantiate these suggestions.  

 

 

Introduction