A randomized controlled study of intrathecalbupivacaine with fentanyl and ropivacaine withfentanyl in lower limb surgeries in adults

Bupivacaine was the first long acting amino amide local anaesthetic used. Ropivacaine is a relatively newer long acting local anaesthetic belonging to the amino amide group. Both have similar structure, pharmacology, mechanism of action and physicochemical property but ropivacaine has an added advantage with lesser cardio toxicity and neurotoxicity. This drug has been introduced in the Indian market only recently and there is a paucity of studies in India which compare it with routinely used hyperbaric bupivacaine intrathecally for orthopedic lower limb surgeries. Therefore this study was to evaluate the clinical efficacy of 0.75% isobaric ropivacaine with fentanyl compared to 0.5% hyperbaric bupivacaine with fentanyl administered inrathecally for orthopedic lower limb surgeries.

80 patients, ASA grade I and II, aged 20-65 yrs scheduled for orthopedic procedures were included in this study. After careful pre-anaesthetic check up and routine investigations, an informed consent was taken from the patients. Patients were kept fasting overnight after a light meal. Premedication with tablet rantidine 150 mg per orally at night and in the morning, 2 hours before the surgery was given to all the patients.

·         After shifting the patients to the operating table, ECG, SpO2, NIBP monitor were attached and baseline values of heart rate (HR), blood pressure (BP) were noted. The patients were preloaded with 10 - 12 ml/kg of Ringer’s lactate over 15-20 minutes after securing 18G intravenous canula in non dominant forearm. Before commencement of anaesthesia patients were instructed on method of sensory and motor assessment. Combined spinal epidural anaesthesia was performed at L3/L4 or L4/L5 intervertebral space using 18G tuohy’s needle for epidural space and 27G Whittacre’s needle for subarachnoid block via needle through needle technique. After confirming free flow c.s.f, study drug was given slowly over 30 seconds. Immediately after intrathecal injection the spinal needle will be withdrawn, epidural catheter will be put through the Tuohy’s needle and the patient will be made to lie supine on the operating table. Surgery will be allowed after level of block reaches T 10 dermatome. An anaesthesiologist who was blinded regarding which local anaesthetic used assessed the sensory and motor block.

GROUP R (n=40):  2.5 ml of 0.75% ropivacaine (isobaric) with 25 µg fentanyl (0.5 ml)

GROUP B (n=40):  2.5 ml of 0.5% bupivacaine (hyperbaric) with 25 µg fentanyl (0.5 ml)

Intra-operatively, heart rate, non invasive blood pressure, continuous ECG, spO2 monitoring, quality of surgical anaesthesia, onset and duration of sensory and motor block, and any other side effects were observed by another researcher who was blinded to the drug given. Post operatively, heart rate, non invasive blood pressure, regression of sensory and motor block, duration of post operative analgesia and any other side effects were observed.

Patients in both the groups were comparable with regard to age, weight, height and type of surgery.

HYPOTHESIS

We hypothesize that addition of intrathecal ropivacaine with fentanyl would be equally effective as compared to that of intrathecal bupivacaine with fentanyl for duration of sensory and motor blockade and hemodynamic response.