Evaluation of the Hemodynamic Response during Laryngoscopy and Intubation using McCOY and Macintosh Laryngoscope Blades

Abstract

Basic elements of general anesthesia includeunconsciousness, amnesia, analgesia, muscle relaxation,diminished motor response to noxious stimuli, and reversibility.Muscle relaxation necessitates securing ventilation withendotracheal intubation. Laryngoscopy forms an importantpart of general anaesthesia and endotracheal intubation.Laryngoscopes are used to view the larynx and adjacentstructures for inserting an endotracheal tube into the trachea.Laryngoscopy aims to obtain good visualization of the vocalcords to facilitate smooth endotracheal intubation. The directlaryngoscopic view is best seen in sniffing in the morning airposition, improving the glottis view. Laryngoscopy triggers majorstress responses, one due to sympathetic stimulation releasingcatecholamines that leads to tachycardia and hypertension,which increases the myocardial oxygen demand, and the otherdue to vagal stimulation leading to parasympathetic activationthat manifests as bradycardia and hypotension. Both may becatastrophic in patients with a known history of ischemic heartdisease.Materials and Methods: This hospital-based prospective,observational study was carried out in the Department ofAnaesthesiology, Shri Ram Murti Smarak Institute of MedicalSciences, Bareilly over 112 patients of ASA physical status Iand II, undergoing elective surgery under general anaesthesiaduring a period of 18 months (February 2021 to June 2022).Results: In our study, a total of 112 patients were included,50.0% of cases were managed by Macintosh blade thoseconsisting of group I, and 50.0% of cases were managed byMcCoy blade, those consisting of group II. Pre-op Heart rate(HR) was 80.56 ± 11.48 and 76.79 ± 10.90 in group I and II,respectively and it was reduced pre-intubation in both groupsand it increased significantly during laryngoscopy (p <0.05).Pre-op systolic blood pressure (SBP) was 116.56 ± 11.55 and119.48 ± 11.41 in group I and II, respectively and it was reducedat pre-intubation in both groups and it increased significantlyduring laryngoscopy (p <0.05). Pre-op diastolic blood pressure(DBP) was 73.17 ± 8.54 and 73.61 ± 10.29 in group I and II,respectively and it decreased at pre-intubation and again, it wasincreased during laryngoscopy (p <0.05). Pre-op mean arterialpressure (MAP) was 87.79 ± 8.64 and 89.28 ± 9.0 in group Iand II, respectively and it was decreased at pre-intubationand again, it was increased during laryngoscopy (p<0.05).ECG was found normal in both groups at all time duration withtachycardia, but no change in the ST segment was noticed inany group.Conclusion: Our study concludes that the McCoy bladeproduces significantly lesser marked hemodynamic changes.The vitals like heart rate, systolic blood pressure, diastolicblood pressure and mean arterial pressure all rise in bothgroups following the laryngoscopy and intubation but increaseswith McCoy were less and insignificant than Macintoshlaryngoscopes.