During induction of general anaesthesia, the act of laryngoscopy and tracheal intubation stimulates the sympathetic
nervous system resulting in an increase in blood pressure and heart rate which may be harmful especially in elderly
patients with pre-existing ischaemic heart disease. Several drugs have therefore been used to obtund this increase
including esmolol, nicardipine, magnesium sulphate and lignocaine. This prospective, double blind randomised
clinical trial compared the efficacy of magnesium sulphate and esmolol in attenuating haemodynamic responses to
laryngoscopy and tracheal intubation. One hundred and twenty six ASA I-II patients scheduled for elective surgery
requiring general anaesthesia with tracheal intubation were enrolled and randomised into two groups: Group 1 (n =
67) received MgSO4 40 mg/kg diluted in 100 ml normal saline administered over ten minutes, whereas Group 2 (n =
59) received a bolus of esmolol 1.0 mg/kg diluted to 10 ml. Systolic and diastolic blood pressures and heart rate were
recorded every minute for subsequent 10 minutes following laryngoscopy and tracheal intubation. Attenuation of the
mean systolic and diastolic blood pressures following laryngoscopy and tracheal intubation was significantly larger
in Group 2 compared to Group 1. Patients in Group 2 had significantly better suppression of heart rate response
compared to Group 1 during the first four minutes after laryngoscopy and tracheal intubation (p