Can Calcium and Sodium Channel Blockers Attenuate Hemodynamic Responses to Endotracheal Intubation?

Aim: Direct laryngoscopy and endotracheal intubation following induction of anesthesia almost always triggers powerful cardiovascular responses. The purpose of this study was to investigate the efficacy of diltiazem (calcium channel blocker), lidocaine (sodium channel blocker) and a combination of these two drugs in the attenuation of circular responses to endotracheal intubation in normotensive patients. Methods: 120 Patients were randomly assigned to one of the following four groups. Group I received a single 0.2 mg/kg IV bolus of diltiazem 1 minute prior to laryngoscopy and intubation (n=30), Group II received a single 1.5 mg/kg IV bolus of lidocaine (n=30) 3 minutes prior and Group III received combination of these two drugs 1 minute prior to laryngoscopy and intubation (n=30). Group IV served as the control and received a single 5 mL IV bolus of normal saline. Changes in heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) were measured and then compared within and between groups. Rate pressure product (RPP) was calculated and evaluated as well. Results:Either diltiazem or lidocaine alone blunts unwanted hemodynamic responses to intubation. However, significantly less circulatory responses were experienced by patients receiving both than those receiving either lidocaine or diltiazem alone. Conclusion: Given the difference in the pharmacological mechanisms of these two drugs, the prophylactic therapy with combination of diltiazem+lidocaine is significantly more effective than any one alone for attenuating hemodynamic changes to laryngoscopy and tracheal intubation, without producing increased risk of hypertension.