Sandeep Prithviraj Pandharpurkar1, Sumalatha2, Ravichandra Dodawad3
BACKGROUND AND OBJECTIVES
Dexmedetomidine, a potent and highly selective α2-adrenoreceptor agonist, possesses desirable properties like sedation, analgesia, sympatholysis and reduces the anaesthetic requirement. Bradycardia and hypotension are the most common side effects of dexmedetomidine. Propofol, currently the most popular induction agent due to its beneficial effects such as suppression of airway reflexes, fast recovery, etc., has the same side effects during induction of anaesthesia. Hence, titration of the above-mentioned drugs can minimise the adverse and retain the desired effects of their pairing. Various loading dosages of dexmedetomidine ranging from 0.33 to 1 μg/kg have been used in pre-induction. Hence, this study was conducted with an objective of comparing and evaluating the effects of different doses of dexmedetomidine on induction dose of propofol and haemodynamics.
MATERIALS AND METHODS
400 patients of ASA physical status I and II, aged 18 to 60 years, undergoing general anaesthesia requiring oral endotracheal intubation were randomly allocated into 4 groups- Group A, B, C received dexmedetomidine 1 μg/kg, 0.6 μg/kg, 0.3 μg/kg respectively, while group D received normal saline. The study drug was diluted to a 20 mL solution and infused over 20 minutes. The sedation was assessed using Brussels Sedation Scale during the same period. Anaesthesia protocol included fentanyl 2 μg/kg, propofol infusion at 80 mg/kg/hour, atracurium 0.5 mg/kg, endotracheal intubation, maintenance with oxygen, nitrous oxide and isoflurane. Dose of propofol for loss of eyelash reflex and verbal response, duration of laryngoscopy and number of intubation attempts were noted. Modified Aldrete’s Score was noted immediately and 10 minutes after extubation.
During the study, we noted that 72.5% of subjects in group A and 65.6% in group B were sedated but arousable with verbal stimuli, at the end of infusion as compared to 18.3% in group C and 3.3% in group D. We observed a reduction in propofol requirement for the loss of verbal response with dexmedetomidine which was 0.93 mg/kg, 1.08 mg/kg, 1.29 mg/kg with group A, group B, group C respectively, while group D (saline) required 1.64 mg/kg propofol.
Dexmedetomidine reduced the induction dose of propofol; a maximum reduction was seen along with 1 μg/kg followed by 0.6 μg/kg and 0.3 μg/kg. Attenuation of haemodynamic response was best seen with 1 μg/kg followed by 0.6 μg/kg while hemodynamic profiles of 0.3 μg/kg of dexmedetomidine and placebo group were similar. Hence, we conclude that 1 μg/kg and 0.6 μg/kg of dexmedetomidine offer a reduction in anaesthetic requirement along with desirable haemodynamics.