Efficacy of 0.5 percent Levobupivicaine versus 0.5 percent Levobupivicaine with Dexmedetomidine in lower limb surgeries under spinal anaesthesia : A prospective randomized double blinded study.

This is a prospective randomised double blinded comparative study conducted at our institution.

The data to be collected are all part of routine care.

 DATA COLLECTION METHOD USED:

considering the time and feasibility of the study, it was decided to apply convenience sampling technique to conduct the study.

Based on a priori one-tailed hypothesis, using parameters of 0.05 alpha, 95% confidence level, 0.75 moderate Effect size, 80% power and Allocation ratio 1:1, Sample size was calculated by using G Power.

The sample size calculated was 114, which was inflated to 120 assuming 5% drop out rate, each group consisting of 60 participants.

TEST:

Unpaired T test will be used for analysis of data (Time of onset and duration of sensory and motor block, Hemodynamic variables, Time taken to walk unaided)

Chi Square test for requirement of post op analgesia.

Data will be summarized by mean and standard deviation.

In this study, p value of <0.05 will be considered statistically significant.

 This prospective randomized double blinded comparative study will be conducted at our institution over a period of 18 months. In this study 120 ASA grade I and II patients between age 18 to 60 years posted for orthopedic surgeries requiring spinal anesthesia will be included.

After taking written informed consent, patients will be randomized into two groups (n= 60) by block randomization method. All patients will be thoroughly examined preoperatively which included history, general physical examination, and checking the vital parameters of the patients such as blood pressure, pulse, respiratory rate and systemic examination, and ASA grading. The patients with a contraindication to spinal anesthesia or major neurological, cardiovascular, respiratory, renal disease, or coagulation abnormalities will be excluded.

All the patients will be nil by mouth fast for at least 6 hours before the procedure. All the routine monitors will be attached and the preoperative baseline readings of noninvasive blood pressure (NIBP), pulse rate (PR), and saturation (SPO2) will be noted. After securing an intravenous (IV) access using an 18-Gauge IV cannula all patients irrespective of the group they belonged to will be preloaded with Ringers lactate 10 mL/kg over 15 min.

Under all aseptic precautions, spinal anesthesia will be performed in the operating room at the L3-L4 interspace, with the patient in the sitting position with neck flexed using a 25Gauge (Quinckes Spinal Needle). The composition of intrathecal drugs depends upon the group to which the patient belongs. The drug combination to be prepared by pharmacist and will be given by an anesthesiologist who was blinded to the drug used in the study. Both the patients and the observer will be blinded to the study drug or the group.

After injecting the intrathecal drug, the following parameters will be observed by an anesthesiologist who will be blinded to the type of drug given to the patient. NIBP will be noted every minute for 10 minutes and then every 5 minutes until the end of surgery. A hypotensive episode is defined as systolic blood pressure (SBP) < 90 mmHg or a decrease in SBP 20% of the baseline value. Hypotension will be managed by rapid infusion of 250 ml of Ringer lactate and 6mg incremental doses of intravenous ephedrine. Clinically relevant bradycardia is defined as HR < 50 bpm and will be managed with incremental doses of 0.3 mg intravenous atropine.  The onset of sensory block is defined as the time taken for loss of sharp sensation with the pinprick test until the T10 dermatome level after injecting the drug (TT10). The recordings will be noted every minute for the initial 10 minutes, and then every 15 minutes thereafter. The maximum height of sensory block reached will be also noted (Hmax). The time taken for regression of the block to L1 will be noted (Treg2). Motor blockade will be assessed using the modified Bromage scale (modified Bromage scale: 1 = unable to move feet or knees, 2 = able to move feet only, 3 = just able to move knees, 4 = full flexion of knees with detectable weakness of hip flexion while supine, 5 = no detectable weakness of hip flexion while supine, 6 = able to perform partial knee bend). The time taken to achieve adequate motor block (TBrom2), defined as a score of 2 on the modified Bromage scale, will be recorded by testing the motor block every minute until a score of 2 achieved.

Surgery  will  be  commenced  once  adequate  sensory  (T10)  and  motor  (modified Bromage 2) block achieved. After the surgery, the patients will be shifted to the post-anesthesia care unit and standard monitoring will be continued. The sensory level and motor blockade will be checked every 10 min. The duration of sensory loss (Tanes) will be defined as the time interval between the onset of sensory block (T10 level) to regression of the sensory block to the L1 dermatome. The duration of the motor block (TMB) will be defined as the time interval between the onset of motor block (modified Bromage scale 3) to the achievement of modified Bromage scale 6 after the surgery. Once a modified Bromage score of 0 achieved, patients will be encouraged to stand up and walk initially with support and then unaided. Post operative follow up, to know the time taken to walk unaided will be noted accordingly. Nausea, vomiting, shivering or any other side effects were followed up post operatively for 24 hours and treated upon.

Postoperative pain was assessed with the help of visual analogue scale (VAS). For post operative pain (VAS >4) injection tramadol 100 mg i.v. was given as rescue analgesia and then can be repeated four hourly if needed (maximum daily dose 400 mg/day).