BACKGROUND Effects of pretreatment with magnesium sulphate for attenuation of haemodynamic response to intubation have been studied previously but its effects on hypertensive patients are not much studied. This study was conducted primarily to find the minimal effective dose of magnesium sulphate to control the haemodynamic response to laryngoscopy and endotracheal intubation in controlled hypertensive patients. METHODS After institutional ethical committee clearance, a randomised, double blinded, clinical study was carried out among 90 American Society of Anaesthesiologists (ASA) physical status II, controlled hypertensive patients of age 30 - 60 years posted for elective surgery. Patients were randomly distributed into three equal groups as group I - received 30 mg / Kg magnesium sulfate and group II - received 40 mg / Kg magnesium sulfate before induction of anesthesia, while group III (control group) received 1.5 mg / Kg lidocaine bolus 90 seconds prior to intubation. The patients’ haemodynamic responses were noted before, during, and after intubation for 10 minutes. Steps taken to manage haemodynamic instability along with serum magnesium levels were also noted. To calculate the sample size, mean value of serum magnesium was taken in three groups to find out effect size as 0.0387. Taking alpha error 0.05 and power required 90 %, the sample size in each group was 30. RESULTS Groups were properly matched for their demographic data. Among all the groups changes in heart rate were comparable (P > 0.05) throughout the study period. In group I there was no significant change in mean arterial pressure (MAP) while in group II and group III a significant decrease was noticed (> 20 % of baseline value). Intervention was required to treat hypotension in significant number of patients in group II (nine patients) and group III (three patients). CONCLUSIONS In controlled hypertensive patients, magnesium in a dose of 30 mg / Kg intravenous is found optimal to attenuate the stress response following laryngoscopy and endotracheal intubation, as further increase in dose can lead to significant hypotension. KEY WORDS Hypertension, Laryngoscopy, Lignocaine, Magnesium Sulphate, Intubation
Comparative study between efficacy of magnesium sulphate and lignocaine in attenuating haemodynamic response to laryngoscopy and endotracheal intubation