METHODOLOGY:

The study will be conducted in the Department of Anesthesiology at Kalinga Institute of Medical Sciences, Bhubaneswar, Orissa. Following approval of institutional ethics committee and obtaining written informed consent, adult patients of both sexes between the age group of 18-55 years belonging to American society of Anesthesiologist (ASA) grade I and II scheduled for lower limb orthopedic surgery under spinal anesthesia will be enrolled in the study.

According to statistical analysis sample size is calculated. Patients will be randomly allocated into two groups by taking to consideration of mean and S.D. of sedation score in group D (1.50 ±0.09) and group F(1.44 ±0.08) at 5% level of significance with 80% minimum study power ,the required sample size is 32 in each group. Accordingly the total required sample subject will be 64.

METHODS:

The selection of patients will be carried out randomly.The study population will be randomized using random number table generated from computer software. Patients will be explained about the anaesthetic procedure they are going to undergo in the language they understand. Pre-anesthetic examination will be done prior to the day of surgery. 

All patients will receive Alprazolam 0.5 mg orally, the night before surgery. After intravenous insertion of an 18-G venous catheter in the operating room, all patients will receive 10ml/kg of Ringer’s Lactate solution for intravascular volume loading before spinal anesthesia. Monitoring  will include electrocardiography, noninvasive blood pressure, pulse oximetry(SpO2) and heart rate . Spinal injection will be performed with aseptic technique in the sitting position through the L3-L4 intervertebral space using a 25G Quincke’s spinal needle.

Patients will be randomly divided into the following groups:

Group D (n=32) to receive 2.5 mL volume of 0.5% hyperbaric bupivacaine and 5μg Dexmedetomidine in 0.5 mL of normal saline. and

Group F (n=32) to receive 2.5 mL volume of 0.5% hyperbaric bupivacaine and 25μg Fentanyl 0.5ml.

 Intrathecal injection will be given over approximately 10–15 sec with the bevel of the needle pointing upward and immediately after completion of the injection patients will be laid back to supine position.

 Sensory blockade is going to be assessed by loss of pinprick sensation to 23G hypodermic needle and cold(cotton swab soaked in spirit) in the mid-axillary line and dermatomes levels will be tested every 2 min until the highest level is reached. Motor block is going to be assessed immediately after sensory block assessment using a Modified Bromage Scale.

The sensory and motor status will be checked every 2minutes after the spinal injection for the first 10 minutes,every 5minutes for the next 10 minutes and thereafter every 20 minutes until the times to regression of sensory level to dermatome S2 and motor scale to bromage 0. Sedation will be assessed by using modified Ramsay sedation scale(1-6)

On achieving T10 sensory blockade level, surgery will be allowed and

The following parameters will be studied:

   1.time to reach T10segment level.

   2.time to reach peak sensory level.

   3.time to reach peak motor block.

   4.time taken for sensory block regression to S2 level.

   5.time taken for motor block regression to bromage 0.

   6.time to first dose of rescue analgesia.

   7.sedation score.

             Haemodynamic variables will be recorded every 5 minutes intraoperatively and every 15 minutes Post Anesthesia Care Unit (PACU) until the patient is discharged. Data regarding the highest dermatome level of sensory blockade, the time to reach this level from the time of injection, time to S2 level sensory regression, time to urination, and incidence of side effects, such as nausea, vomiting, shivering, pruritus, respiratory depression, sedation, bradycardia , hypotension and urinary retention will be recorded.

Postoperatively, the pain score will be recorded by using visual analogue pain scale (VAS).  Inj. Paracetamol 15mg/kg i.v. infusion will be given as rescue analgesia when VAS was >4.  

       Quantitative data will be analysed by student’s ‘t’ test.

Qualitative data will be analysed by Chi-square test.

P value < 0.05 would be considered statistically significant.