Comparison of nalbuphine versus clonidine as an intrathecal adjuvant to hyperbaric bupivacaine in orthopedic lower limb surgeries

Rationale: Lower limb fracture is the commonest orthopedic trauma requiring surgery. Spinal anesthesia is the preferred choice for orthopedic lower limb surgeries. Due to its limited duration of block, intrathecal adjuvants are often used to prolong the duration of anesthesia. Opioids are commonly used intrathecal adjuvant but, are also associated with side effects like hypotension, bradycardia, pruritis etc. Recently, nalbuphine has been safely used as intrathecal adjuvant and found to be promising without additional side effects. Intrathecal clonidine is known to prolong analgesia and quality of subarachanoid block. Few studies have compared nalbuphine with clonidine but the results reported are inconsistent.

Aim: Comparison of nalbuphine versus clonidine as intrathecal adjuvant to hyperbaric bupivacaine in orthopedic lower limb surgeries.

Objectives: To compare the effect of nalbuphine versus clonidine as intrathecal adjuvant to bupivacaine and study its effect on:

Primary objective:

To know the duration of post operative analgesia

Secondary objectives:

1.      Sensory block: highest level and duration of block

2.      Motor block: Onset, intensity and duration of block

3.      Adverse effects

Setting: The study will be conducted in Department of Anesthesiology and Critical Care, University College of Medical Sciences and Guru Teg Bahadur Hospital, Delhi.

Study Design: Randomized double blind controlled study.

Duration: November 2018 to April 2020

Population/participants: Patients belonging to ASA I and ASA II, between the age of 18-60 years and height of >150cm and <180cm will be included in the study.

Sample Size: Considering the variability of 6.04 minutes, 30.76 minutes and 5.85 minutes in duration of analgesia with nalbuphine 0.8mg, clonidine 15mcgandcontrol respectively from previous studies.9, 12 Now to estimate a difference of 50 minutes among these drugs at α=5% and Power=90%, a  sample size of 10 patients is required in each group. Due to availability of resources and time, we propose to consider 21 patients in each group. 63 patients will be divided into three groups of 21 each using a computer generated random number table.

Methods: Under all aseptic precautions subarachanoid block will be performed and patients will receive 3.5 ml of test drug solution containing 15mg of bupivacaine along with either 1mg of nalbuphine or 30mcg of clonidine or 0.9% of normal saline according to the groups allocated. The test drug solution will be prepared by anesthesiologist not involved in the study. Patients will be assessed for characteristics of spinal anesthesia (sensory and motor block), sedation score, hemodynamic parameters, pain score and side effects.

Statistical Analysis: Between the 3 groups comparison will be done by one way ANOVA followed by TUKEY’s test. Hemodynamic parameters will be compared by repeated measure ANOVA and followed by DUNNETT’s test.

Qualitative parameters will be compared using Chi-square test/Fischer’s exact test.

A p-value of <0.05 will be considered significant.