Comparing the effects of intrathecal buprenorphine versus fentanyl as adjuvant to hyperbaric ropivacaine in lower limb surgeries

Spinal anaesthesia is a widely used technique in anaesthetic practice for gynaecological, lower abdominal, pelvic and lower limb surgeries. Spinal anaesthesia offers certain advantages such as:

â—It ensures high patient satisfaction

â—Cost effective

â—Requires lesser duration of hospital stay

â—Has decreased incidence of nausea and vomiting

Though subarachnoid block is widely used for lower limb surgeries, it has practical limitations in prolonged surgeries.1 To prolong the duration of sensory-motor block and limiting the cumulative dose requirement of local anaesthetics, co-administration of adjuvants has the potential to improve efficacy of subarachnoid blocks and decrease local anaesthetic toxicity.2 Various drugs such as morphine, pethidine, phenylephrine, neostigmine, ketamine, and many others have been used. Among these buprenorphine and fentanyl are also tried as an adjuvant to LAs to prolong the anaesthetic effects of LAs.

After approval from the Institutional Ethics Committee, participants will be explained about the nature of the study and written informed consent will be obtained. A thorough pre-anaesthetic evaluation will be done a day prior to the surgery. All patients will be kept nil per oral 8 hours for solids and 2 hours for clear liquids.

Patients will be shifted to the operation theatre after preoperative monitoring of vitals and confirming the NPO status of patient. Standard monitors will be attached including electrocardiography, peripheral oxygen saturation and noninvasive blood pressure monitor. All the basal parameters will be recorded. All patients will be coloaded with Ringer’s lactate solution 10 ml/kg body weight. Under strict aseptic conditions, subarachnoid block will be performed at L3-L4 inter vertebral space through midline approach using a 25gauge Quincke-Babcock spinal needle. After ensuring the free flow of clear CSF, patient will be given intrathecal 3 ml of 0.75% ropivacaine heavy along with 0.5 ml of buprenorphine or 0.5 ml of fentanyl as adjuvant according to the preference of concerned anaesthesiologist.

The sensory and motor block levels assessment was performed at 5 mins interval for the first 15mins then 15 mins interval for half an hour followed postoperative room (first one hour of shifting)

1.SENSORY BLOCK:

Onset of sensory block will be taken as the time from injection of the study drug in the subarachnoid space until the time when maximum sensory level is achieved. The sensory blockade will be assessed with bilateral cold spirit swab method. The highest dermatome showing sensory analgesia will be taken as the upper segmental level of block when it remained same even after 5 min. Total duration of sensory block will be taken as an interval from intrathecal administration of the study drug to regression of sensory block to S1 level.

2.MOTOR BLOCKADE:

The degree of motor block will be assessed by the modified Bromage Scoring System.

3.HEMODYNAMIC CHANGES

Systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP) and heart rate (HR) will be recorded every 3 mins interval for the first 12mins then 5 mins interval for 30mins followed by every 15mins for another 30min and then post operatively hourly for two hours.

4.POST OPERATIVE PAIN:

Post operative pain is assessed every 30 mins till the first 2 hrs and then every 2 hrs till 24 hrs or once patient complaints of pain according to NRS scale. NRS will be explained to the patient. NRS is a segmented numerical version of the visual analogue score (VAS) in which the respondent selects a whole number that best reflects the intensity of his/her pain. It is an elevenpoint scale ranging from 0 to 10 where 0 represents no pain and 10 meaning the worst imaginable pain.

5.ADVERSE EFFECTS IF ANY:

Complications such as nausea, vomiting, urinary retention, shivering will also be noted and treated appropriately

Once the required data is collected, patients who received 0.5 ml buprenorphine as adjuvant to intrathecal ropivacaine heavy will be termed as Group B and patient who received 0.5 ml fentanyl as an adjuvant will be termed as Group F.