120 patients will be divided into three groups of 40 each and randomly allocated to one of the three below-mentioned groups as Group BN - Bupivacaine with nalbuphine (n=40), Group LN - Levobupivacaine with nalbuphine (n=40) and Ropivacaine with nalbuphine (n=40) by computer generated program assigning random table number. Our study was a prospective randomized double-blinded study, where the patient and the primary investigator assessing the outcome were unaware of the group they were allotted.

     The method of randomization used was block randomization in which the study population was divided into sizes of six. The randomization codes for each subject were then enclosed in a sealed envelope, concealment ensured using sequentially numbered opaques sealed envelope, and the corresponding number was represented with the concerned group for the study. Prior to the study, the anaesthesiologist who were not involved in the study was made to pick among the lot of opaques concealed envelope which was handed over to the anaesthesiologist involved in the concerned surgery, who would admister the study drugs and observe the parameters.

     Group BN received 0.5% Heavy Bupivacaine (3.2ml) + 0.6mg of Nalbuphine   

                (0.3ml) to a total volume of 3.5 ml for spinal anesthesia

     Group LN received 0.5% Heavy Levobupivacaine (3.2ml) + 0.6mg of Nalbuphine

                (0.3ml) to a total volume of 3.5 ml for spinal anesthesia

     Group RN received 0.75% Heavy Ropivacaine (3.2ml) + 0.6mg of Nalbuphine

                 (0.3ml) to a total volume of 3.5 ml for spinal anesthesia

     Pre-anaesthetic evaluation was done on the day before surgery which includes detailed history, airway and systemic examination. Biochemical and pathological blood investigations were done. Starvation guidelines followed was 12 hours for fatty foods, 8 hours for solids and clear liquids encouraged till two hours prior to surgery. Antiaspiration prophylaxis was supplemented with Tablet.Pantoprazole 40mg and Tablet.Metoclopramide 10 mg the day before surgery at night 10 pm and informed written consent was obtained.

     On the day of surgery, before shifting the patient inside the operating room, starvation status, consent for surgery and anaesthesia including surgical safety checklist was done. An 18G intravenous cannula was secured intraoperatively and Plasmalyte intravenous fluids was started at a rate of 2ml/kg/hour. Basic monitoring gadgets like chest leads, noninvasive blood pressure monitoring, pulseoxymetry was attached after the patient was received in the operating table and baseline readings recorded. 

     The spinal anesthesia procedure was explained to the patient in their vernacular language. Under strict aseptic precautions, skin infiltration was done with 2ml of 2% lignocaine and a subarachnoid block performed with the patient in the left lateral position choosing preferably L3-L4 lumbar interspinous space using 25G Quincke spinal needle. After establishing free flow of CSF, the study drugs were supplemented to one among the three groups by random allocation number.

     The study medication was prepared by the person (another anaesthesiologist who was not involved in the study) to ensure the blinding of the anaesthesiologist. Group BN received 0.5% Heavy Bupivacaine (3.2ml) +0.6mg of Nalbuphine (0.3ml) to a total volume of 3.5ml, Group LN received 0.5% Heavy Levobupivacaine (3.2ml) +0.6mg of Nalbuphine (0.3ml) to a total volume of 3.5ml and Group RN received 0.75% Heavy Ropivacaine (3.2ml) +0.6mg of Nalbuphine (0.3ml) to a total volume of 3.5ml for spinal anesthesia and drug was administered over a duration of 35 seconds. Patient was turned supine post spinal injections and no table tilt was given to any of the groups.

     The following parameters were noted after obtaining subarachnoid blockade.

1.      Time of drug administration in spinal space

2.      Time of onset of complete sensory and motor block

3.      Duration of sensory block (sensory level was assessed by pin prick method)

4.      Duration of motor block (which was assessed by modified Bromage scale)

5.      Duration of postoperative analgesia (Effective analgesia time of onset of sensory block to the first request of rescue analgesics by using VAS score)

6.      Time for complete regression of spinal anesthesia

7.      Modified Bromage Scale

8.      Haemodynamic parameters like heart rate, blood pressure, and oxygen saturation

Results for the study were recorded from baseline and continued monitoring the readings at an interval of 1, 3, 5, 10, 15, 30, 60, 90, 120, 180, 240, and 300 minutes intraoperatively following the subarachnoid blockade. The requirement of postoperative analgesia and regression of sensory and motor levels of the blockade was evaluated every 60 minutes for the next 4 hours in the recovery unit during the observation period. Visual analogue scale (VAS) were taught how to expess the degree of pain on the scale of 0 to 10 and were asked to mark on the scale according to the degree of pain. When VAS score was more than 4, rescue analgesia was given with injection tramadol 25mg intravenously.

Management protocol for drug-related complications :

     The hemodynamic parameters were monitored. Hypotension was noted when systolic Blood Pressure recorded less than 90mmHg and was treated with intravenous crystalloids and if needed vasopressors like an injection of Mephentermine 6mg IV as incremental bolus doses. Bradycardia was noted when the heart rate was less than 50 beats per minute and treated with Injection Glycopyrrolate 0.02mg per kilogram IV as bolus if required. Injection of Ondansetron 4mg IV supplemented if there is nausea or vomiting.

Statistical analysis :

    The observations and results were compiled and data were statistically analyzed using the SPSS 28.0 software using Chisquare and Kruskal-wallis one way analysis. Baseline characteristics were presented as mean ± S.D. Binomial data were compared using Chi-square test (p value less than 0.05 were considered as statistically significant) and block characteristics using Kruskal-Wallis one way analysis. Two-tailed Mann-Whitney U test for multiple two way testing to see post hoc comparisons within-subject variability for statistical significance.