Dexmedetomidine infusion as an anaesthetic adjuvant for maintenance of anaesthesia in patients undergoing major surgeries (A comparison of two different doses)

Abstract

Objectives: To compare the effect of Dexmedetomidine 0.2g/kg/hr and 0.4g/kg/hr infusions as an adjuvant for maintenance of anesthesia in surgeries under GA, on the following parameters:1) Changes in hemodynamic parameters; 2) Requirement of inhaled anesthetic agents and muscle relaxants; 3) Assessment of post operative sedation and analgesia. Material and methods: Total of 60 patients was selected for these studies conducted between 2012 and 2014 and were randomly divided into 2 groups. Group A (inj. Dexmedetomidine 0.2 g/kg/hr) and Group B (inj. Dexmedetomidine 0.4g/kg/hr). All patients belonging to ASA I and II of both sexes aged 18 to 60 yrs, were included in this double blinded parallel grouped comparative randomised study. Haemodynamics were monitored before giving the study drug and post induction along with concentrations of inhalational agents and muscle relaxants being recorded 1 minute post induction, 5 min post induction, thereafter every 15 min till end of surgery and field of surgery was assessed via FOS bleeding score. Results: Both the groups were comparable in terms of age, weight and gender.(p.0.05) statistically not significant. Dexmedetomidine 0.4 g/kg/hr (Group B) showed a maximum reduction of 41.3% in the mean Iso concentration requirement compared to 31.4% in (group A). Difference was statistically very highly significant (p 0.001). Group B showed 20% greater reduction in the requirement of muscle relaxants intraoperatively than Group A. It was statistically very highly significant (p 0.001). Group B showed a maximum reduction of 20% in heart rate with respect to baseline in comparison to 7% reduction in Group A Difference was statistically very highly significant(p 0.001). The fall in systolic BP was 15.7% in Group B compared to 3.5% reduction in Group A with respect to baseline. Difference was statistically very highly significant (p 0.001). The reduction in diastolic blood pressure was 13% in Group B compared to 3% in Group A. Difference was statistically very highly significant (p 0.001). Ramsay sedation score in Group B at 1 hour post operatively was higher compared to Group A (p 0.05) whereas at 4 hours it was comparable. VAS pain score was 6 in group B compared to 6.7 in Group A, (p 0.001) statistically very highly significant. Duration of analgesia was longer in Group B (18 hours) compared to Group A (6 hours). Conclusion: Dexmedetomidine 0.4 g/kg/hr appears to be better than dexmedetomidine 0.2g/kg/hr. and provides greater reduction in requirement of anaesthetic agents, better haemodynamic stability, sedation and analgesia.