Effects of labetalol and diltiazem on the intraocular pressure responses to tracheal intubation

ABSTRACT

The effects of labetalol and diltiazem on intraocular pressure [IOP] during laryngoscopy and endotracheal intubation were investigated in 30 patients, scheduled for elective extraocular ophthalmic operations. Anaesthesia was induced by thiopentone Na followed by succinylcholine to facilitate tracheal intubation, anaesthesia was maintained by oxygen, and Halothane 1-2% manual inflation of the lungs, then spontaneous respiration. Pretreatment with labetalol [0.2 mg/Kg] 4 minutes before intubation lead to attenuation of the mean heart rate [MHR], and mean arterial pressure [MAP] changes, although these changes were still significant [t=6.79, 8.84]. Pretreatment with diltiazem [0.3 mg/Kg] 2 minutes before intubation lead to attenuation of the MHR, and MAP. These changes were still significant [t=5.58, 7.41]. The attenuation of MHR, MAP were less in labetal group than in diltiazem group. Both drugs produced a significant reduction in IOP at intubation, 2.5 and 5 minutes after intubation in relation to the preoperative value. The decrease in IOP was less in labetalol group than in diltiazem group. In conclusion, single dose of IV labetalol and diltiazem before intubation is a practical and effective method of attenuating hypertension, tachycardia and ocular hypertension in response to tracheal intubation