Comparison of Intravenous and Atomized TopicalLidocaine in Attenuating the HemodynamicResponses to Tracheal Intubation inSurgical Patients with pre existing hypertension:Randomized Controlled Trial.

Laryngoscopy and tracheal intubation following induction of anesthesia have been reported to cause significant increases in blood pressure and pulse rate. These changes are usually of short duration and pose little threat to healthy patients. But in patients with hypertension, short periods of hypertension or tachycardia may increase the risk of cardiac ischemia and other vascular events. Various pharmacological drugs have been tested in an attempt to prevent or attenuate these hemodynamic responses. Deep general anesthesia, intravenous administration of adrenergic blocking drugs like esmolol , or vasodilating drugs like diltiazem and nitroglycerin are often tried to prevent or attenuate the hemodynamic response to laryngoscopy and intubation. Though they are proven to reduce the intubation response, their undesirable side effects like hypotension, bradycardia, bronchospasm, and conductionblocks warrant close monitoring and maynecessitate monitoring of intra-arterial pressure.Lidocaine is the most commonly studied drug inthis regard either through intravenous route or aslaryngo-tracheal topical anesthetic drug prior tointubation. Lidocaine is also a common drugavailable in the operation rooms and the effect oflidocaine to attenuate the hemodynamic responseto tracheal intubation is well proven by manystudies but the majority of them are limited tointravenous route of administration in low-risksurgical patients. Topical lidocaine has also beenshown to attenuate the hemodynamic response tointubation. Theoretically topical lidocaine due toregional action may suppress the cardiovascularreflex response to laryngoscopy and intubation ascompared to intravenous administration. Also,the systemic toxicity of lidocaine may beavoided. Studies directly comparing intravenousand topical lidocaine in attenuating intubationresponse are very limited to low risk surgicalpopulation and lack adequate power to concludethe superiority of each other. Hence our study hasbeen undertaken to make this direct comparisonbetween topical and intravenous lidocaine inaddition to fentanyl in attenuating the intubationhemodynamic response. Patients with controlled hypertension whose blood pressure is maintainedbelow 140/90 millimeter of mercury with a single or combination of oralmedications belonging to American Society of Anesthesiologists ASA IIposted for noncardiac elective surgery are selected as the study population.They will receive premedication on the night prior to the surgery and at least90 minutes before the surgery which includes Diazepam 100 mcg/kg with anupper limit of 10mg and aspiration prophylaxis drugs like Metoclopramide10 mg and Famotidine 10 mg. The patients will be brought into the operatingroom, allowed to relax for a few minutes till they feel calm and composed,following which monitors are attached and continuous monitoring of noninvasive blood pressure, pulse rate, oxygen saturation and ECG (leads I, II,III and V5) will be started. An intravenous access will be secured under 1mlof 2% lidocaine skin infiltration and injection Fentanyl 2 mcg/kg will beslowly injected subsequently. Simultaneously, preoxygenation with 100%oxygen will be started using a circle breathing system. Five minutes afterinjection of Fentanyl, baseline recordings of systolic, mean, diastolic bloodpressure, pulse rate, and ST segment measurement from leads II and V5 willbe noted and Rate pressure product will be calculated. Sealed opaqueenvelopes will be opened at this time. One syringe labeled as topical drugand another one labeled as the intravenous drug depending on the groupallocation will be prepared by the independent anesthesiologist not involvedin the study. Then they will be induced with intravenous 10% Propofol at a dose of 2 mg/kg until the loss of verbal response of the patient. Thenvecuronium 0.1 mg/kg will be administered. The LMA Madgic intubationatomizer (Teleflex) device will be inserted into the oral cavity of patients inthe topical lidocaine(TL) group and mask ventilation will be started withsevoflurane in oxygen air mixture. After insertion of the LMA Magic deviceanother reading of blood pressure (systolic, mean and diastolic)and heart ratewill be noted. To facilitate atomization of topical drug, Oxygen at the flowrate of 2 L/ min will be administered through one of the ports of the devicefrom a separate oxygen flow meter. The patients in the Topical Lidocaine(TL) group will receive 1.5 mg/Kg of 2% lidocaine through the atomizerover period of 30 seconds. The Intravenous Lidocaine (IL) group will receive1.5 mg/Kg of 2% lidocaine intravenously. The drug will be injected over aperiod of 30 seconds. Mask ventilation will be continued so thatlaryngoscopy and intubation are performed three minutes after the deliveryof lidocaine. During mask ventilation the end tidal carbon-di-oxide will bekept between the range of 35 to 45 mmHg. The intubation will be performedby an experienced anesthesiologist (Third year Junior Resident / SeniorResident / Consultant) to avoid prolonged intubation or multiple attempts atintubation. Laryngoscopy is done with a standard McIntosh blade andtracheal intubation is done with an appropriate size tracheal tube under directvision. Following intubation, blood pressure, pulse rate, ECG and EtCo2, arenoted every one minute for the first 10 minutes by the investigator blinded tothe group allocation.