Comparison of Glottic View and Haemodynamic Stress Response Associated with Laryngoscopy using the Macintosh, McCoy and Miller Blades in Adult Patients

ABSTRACT

Introduction: Laryngoscopy induces haemodynamic responsewhich has implications for patients with cardiovascularillnesses. We devised this study to compare the laryngoscopicview of the glottis obtained with the Macintosh, McCoy andMiller blades, and corresponding haemodynamic changes.Material and Methods: 105 ASA grade I and II patientsrandomly divided into three groups were intubated usingMacintosh, McCoy and Miller blade respectively. Cormackand Lehane grade of glottic view obtained, heart rate, systolicand diastolic blood pressure at baseline, immediately beforeinduction, following induction, and at 1, 3 and 10 minutesafter intubation were noted. Epi Info 7.2 was used forstatistical analysis. Chi square and ANOVA tests were appliedto compare haemodynamic parameters.Results: 18 patients (51.4%) were CL grade I and 17 (48.6%)were CL grade II in Macintosh, 24 (68.6%) were CL gradeI and 11 (31.4%) were CL II in McCoy and, 32 (91.4%)were CL I and 3 (8.6%) were CL II in Miller group. Risein heart rate following intubation was greatest with Millerblade, followed by Macintosh and least with McCoy, andwas statistically significant (P< 0.01). Rise in both, systolicand diastolic blood pressure following intubation was highestwith the Miller blade, followed by Macintosh and least withMcCoy, and the difference compared with baseline values wasstatistically significant (P<0.01).Conclusions: Miller blade provides best visualization of larynxbut McCoy blade produced least haemodynamic response,hence the latter is preferable when less haemodynamicresponse is desired.