A Comparative Randomized Study Between Dexmedetomidine, Magnesium Sulphate and Lidocaine on the Pressor Response to Laryngoscopic Intubation for Laparoscopic Gynecological Surgery

Fast-track laparoscopic gynecological surgery usually done under general anesthesia (GA). Laryngoscopy and endotracheal intubation are necessary for effective control of airway and ventilation, but it has deleterious effects such as hypertension and disrhythmia. These hemodynamic changes are due to the reflex sympathetic activity and the magnitude of response is directly proportional to the duration and strength of laryngoscopy. Several drugs and techniques have been tried to attenuate the stress response to laryngoscopy and endotracheal intubation, but none of them have proven to be ideal.

Lidocaine is an amide synthetic local anesthetic, which is used in treatment of ventricular dysrhythmias and as a prophylaxis in ventricular tachyarrhythmia. It has cardio stabilizing action.

Bromage showed that its intravenous (IV) use blunted pressure response to intubation. An IV dose of lidocaine 1.5 mg/kg has been proved to attenuate stress responses during laryngoscopy and intubation.

Dexmedetomidine is a highly selective alpha 2 receptor agonist and possesses the properties of sedation, analgesia, and opioid sparing effect. It has been shown to reduce the laryngeal stress response, reduce the requirement of intravenous (IV) anesthetics, and provides hemodynamic stability.

Magnesium sulphate (Mg SO4) is the fourth most abundant cation in the body and the second most abundant intracellular cation. It activates many of the enzyme system. Mg SO4 inhibits the release of catecholamines from the adrenal medulla and adrenergic nerve endings and is effective in attenuating the blood pressure (BP) response to tracheal intubation. Puri et al showed that MgSO4 50 mg/kg administered before laryngoscopy could attenuate the pressor response to tracheal intubation better than lidocaine.