Comparing the first-attempt tracheal intubation success of the hyperangulated McGrath® X-blade vs the Macintosh-type CMAC videolaryngoscope in patients with cervical immobilization: a two-centre randomized controlled trial.

Abstract

We compared the hyperangulated McGrath X-blade with the Macintosh-type CMAC videolaryngoscope through the use of manual in-line stabilization on patients. The primary hypothesis was that the McGrath X-blade has a similar first-attempt success rate as the CMAC videolaryngoscope. 210 patients of ASA physical status I to III, aged 21 to 80years old, undergoing general anesthesia requiring tracheal intubation were prospectively recruited into this two-centre randomized controlled trial, from June 2016 to April 2019. Patients with history of or predicted difficult airway, pre-existing dental risks, BMI > 35kg/m2, cervical spondylosis or myelopathy, aspiration risks, patients who declined to participate or lacked the mental capacity to give consent were excluded. Participants were intubated using either hyperangulated McGrath X-blade (MGX) or Macintosh-type CMAC (CM) videolaryngoscopy, with manual in-line stabilization. Primary outcome measured was first-attempt tracheal intubation success. Secondary outcomes included overall successful intubation within 2 attempts or 120s, time to intubation, glottic view obtained and intubation-related complications. First-attempt success rates were 71.4% in the MGX group vs. 79.0% in the CM group (p = 0.26), with an absolute difference of -7.6% (95%CI -20%,5.0%,p value = 0.26),but this trial was underpowered to detect a difference. Overall success was 91.4% (MGX) vs. 92.4% (CM) (p > 0.99). The Cormack & Lehane laryngeal grade was superior in the MGX group compared to CM group (Grade I: MGX 44%, CM 23%; Grade II: MGX 53%, CM 45%; Grade III: MGX 3%, CM 32%; p < 0.001). The median time to intubation using the MGX was longer than the CM [MGX 55.5s (42.1-78.3), CM 43.8s (38-55.3); p < 0.001]. Our study did not demonstrate a significant difference in efficacy between the McGrath X-blade and the CMAC videolaryngoscope. In patients with manual in-line stabilization, no anticipated airway difficulty and in the hands of experienced operators, the McGrath X-blade provided superior glottic views but conferred no advantage over the C-MAC, with a longer median time to intubation compared to the CMAC videolaryngoscope.Trial registration: Australian New Zealand Clinical Trial Registry (ACTRN12616000668404).