Background: The experiences of seasoned practitioners with the new C-MAC indirect videolaryngoscope system have shown promising results in the management of difficult airways. However, a comparison of direct and indirect laryngoscopy utilizing the C-MAC system as its own control has not been performed in a cohort of anesthesiologists-in-training. The primary aim was to compare direct and indirect laryngoscopy in terms of intubation time with secondary outcomes including laryngoscopy time and airway view with the same size 3 blade.
Methods: The study was registered with www.clinicaltrials.gov (NCT01104090). Oral and written informed consent was obtained from 50 adult patients with BMI < 40 kg/m2 who required general anesthesia for elective surgery with tracheal tube placement. The patients were randomized to two groups, each receiving two laryngoscopies, n=25 direct-first and n=25 indirect-first.
Results: All patients except for one were successfully intubated on the first attempt. The intubation time was 12.3±11.1 sec immediately following videolaryngoscopy (direct laryngoscopy first group) and 9.8±7.1 sec immediately following direct laryngoscopy (videolaryngoscopy first group), p=0.35. The first laryngoscopy time was 8.7±4.7 sec in the direct group and 13.3±10.7 sec in the indirect group, p=0.06. Twenty-percent of direct first cases compared to 0% of indirect first cases showed an improvement in airway view score by at least two classes on the second laryngoscopy, p=0.02. Backward-upward-rightward pressure was used in 36% of direct first and 12% of indirect first patients, p=0.047.
Conclusions: This study corroborates previous results on the use of the C-MAC videolaryngoscopy system during endotracheal-assisted intubation. Although there was no difference in intubation time between direct laryngoscopy and videolaryngoscopy, the C-MAC system was found to improve laryngeal views and reduce the number of necessary laryngeal manipulations. A larger randomized study utilizing a similar model is necessary to definitively determine significant clinical results.
Trial registration: ClinicalTrials.gov NCT01104090.
Keywords: Indirect laryngoscopy, airway management, difficult airway, videolaryngoscopy, intubation