Spinal anaesthesia is usually performed anaesthesia technique for infraumbilical and lower limb surgeries. It provides sensory as well as motor blockade. Spinal anaesthesia continues to dominate the field of anaesthesiology because of its rapid onset, simplicity and low complications compared to general anaesthesia. Multiple local anaesthetic agents were used over a period of time. Hyperbaric Bupivacaine 0.5% being the most used one due to its longer duration of action and addition of adjuvant further increased the duration of spinal anaesthesia. Different adjuvants cause different changes in hemodynamic parameters, sensory blockade, motor blockade and analgesia. Fentanyl is a synthetic opioid drug, which is most commonly added as an adjuvant in intrathecal injection because it is more potent, providing better analgesia, hemodynamic stability with better safety profile.

Spinal anaesthesia causes a sympathetic denervation resulting in hypotension because of the rapid sympathetic block.In the conventional technique of spinal anaesthesia bolus dose of drug which many a times gives higher level of anaesthesia than the desired, thus causes more hypotension. In comparison to this, if the drug is administered in two or more divided doses (fractionated doses) in the subarachnoid space rather than entire dose being injected as one dose, occurence of hypotension is reduced. 

Fractional spinal anaesthesia technique has been recently introduced. In fractional technique of spinal anaesthesia, after giving 1st fractionated dose , the drug will settle down as the patient to be kept in sitting position for 30-90 seconds, so desired and predicted sensory and motor blockade to be achieved. Then after 2nd fractionated dose is injected and after giving 2nd fractionated dose the patient to be made supine which leads to slow distribution of the drug which prevents hypotention and provides better hemodynamic stability. Fractional spinal anaesthesia is used for a number of surgical procedures because of more hemodynamic stability, longer duration of sensory and motor blockade and longer duration of analgesia in camparison to conventional spinal anaesthesia.

Few studies have been done and published comparing both of these techniques, fractional v/s conventional spinal anaesthesia. Both of these techniques of spinal anaesthesia are used interchangeably in our institute. But, the data collection on comparing both of these techniques has not been done previously. The data being collected from this study, might be helpful for establishing some beneficial and advanced/recent protocol in the anaesthesia department, thereby to the institute and anaesthesia society also. So, the present study will be conducted to compare the efficacy and safety of fractional spinal anaesthesia v/s conventional spinal anaethesia using hyperbaric bupivacaine 0.5% (3ml–15mg) as a local anaesthetic and fentanyl (0.5ml-25mcg) as an adjuvant in patients of infraumbilical and lower limb surgeries.