Comparison of Fractionated versus Bolus Dose Injection of Drug in Spinal Anaesthesia for Lower Limb Surgeries

INTRODUCTION : Spinal anaesthesia (SA) with bupivacaine is routinely used to provide anaesthesia for lower limb surgeries. To prevent hypotension, there are various measures such as administration of fluids either colloids or crystalloids before SA and administration of a prophylactic vasopressor. AIM AND OBJECTIVES:To compare fractionated dose with bolus dose in SA for haemodynamic stability and duration of analgesia in patients undergoing elective lower limb surgeries. MATERIALS and METHODS:After the Institutional Ethics Committee approval and written informed consent, the present study was carried out in 60 patients (30 in each group) of the ASA I?II, age from 15 to 80 years, height from 140 to 180 cm. . After aspiration of cerebrospinal fluid, injection bupivacaine 0.5% heavy was injected according to respective groups, B(bolus) and F(fractionated). Total dose of 3ml of bupivacaine 0.5% heavy, initial two third dose was given followed by one?third dose after 90s, both doses given at a rate of 0.2 ml/s. After injection of initial two?third dose, the syringe were kept attached to the spinal needle for remaining 90 s, after which remaining one?third dose was administered. Hypotension was treated when mean arterial pressure (MAP) decreases ?20% of baseline with injection mephentermine 1mg given IV and will be repeated when needed. The number of hypotensive episodes and mephentermine used were recorded for each patient8. Bradycardia if any (HR of less than 60 beats/min) were treated with IV atropine 0.6 mg. RESULTS : The patients in fractionated group showed significantly prolonged sensory and motor block and also prolonged analgesia. There were lesser episodes of bradycardia and hypotension emphasising a more stable haemodynamics in the group compared to the bolus group CONCLUSION:Fractionated dose of spinal anaesthesia provides more haemodynamic stability and prolonged sensory and motor blockade and also longer duration of analgesia.