Intubating conditions and stress response to laryngoscopy: Comparison between macintosh and Mccoy’s type laryngoscope blades

Abstract

Background and Aims: Laryngoscopy and endotracheal intubation are critical aspects of general anesthesia, often provoking significant stress responses that impact circulatory parameters. This study aims to compare the hemodynamic stress responses and intubation conditions between the Macintosh and McCoy blades in patients with ASA grades I and II undergoing various surgical procedures under general anesthesia.
Methods: A total of 100 patients were randomly assigned into two groups: Group A (Macintosh blade) and Group B (McCoy blade), each consisting of 50 patients. Hemodynamic parameters, including heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP), were recorded at Pre-Induction, At the Start of Laryngoscopy, Immediately After Intubation, 1 Minute After Intubation, 3 Minutes After Intubation, 5 Minutes After Intubation, 10 Minutes After Intubation. Intubation ease was evaluated by recording the duration of laryngoscopy, Cormack and Lehane Grades, Modified Mallampati scores, and the necessity for optimal external laryngeal manipulation (OELM) or stylet use.
Results: The Macintosh group exhibited significantly higher HR, SBP, DBP, and MAP immediately after intubation compared to the McCoy group (p < 0.001). The McCoy blade was associated with better attenuation of the hemodynamic response and facilitated improved laryngeal view under Cormack and Lehane grading, particularly beneficial in patients with higher Mallampati grades.
Conclusion: The McCoy blade offers superior hemodynamic stability and enhanced visualization during intubation compared to the Macintosh blade, making it potentially more advantageous for patients with challenging airways, although further research in Mallampati grades III and IV is warranted.