Comparison of post operative analgesic effects of intrathecal nalbuphine and intrathecal clonidine in patients undergoing elective lower limb orthopaedic surgeries : a prospective randomized double blind study.

SOURCE OF DATA:  This prospective, randomized, double blind interventional study was carried out in the department of anaesthesiology, SDM College of Medical Sciences and Hospital, Dharwad from December 2015 to May 2017 with the permission from hospital ethical committee along with well-informed written consent from all patients undergoing elective lower limb orthopaedic surgeries requiring sub-arachnoid blockade as a modality of anaesthesia. 99 patients were included randomly based on sealed envelope method into three study groups comprising 33 patients in each. Study Design:  A prospective randomized double blinded clinical study. Inclusion Criteria: 1. Aged between 18 and 60 years 2. ASA Physical status 1, 2 and 3. 3. Patients undergoing elective lower limb long bone orthopaedic surgery under sub arachnoid block. Exclusion Criteria: 1. Patients with ischemic heart disease, neurological or psychiatric disorders, renal or hepatic insufficiency. 2. Pregnant or lactating women. 3. Obese as defined by a BMI of more than 30 kg/m2.  4. Patients on α antagonists.  5. Patients allergic to the medications being used.  6. CNS and local infections.  7. Spine deformities, raised intracranial pressure and progressive neurological disorders. 8. Those parents who refuse consent.   16   Sampling Procedure:  The study was conducted on patients undergoing elective surgery at SDM College of Medical Sciences and Hospital. All the patients falling under inclusion criteria were numbered and the patients were randomly allocated into either nalbuphine group (Group N), clonidine group (Group C) or control group (Group Z) using sealed envelope technique.   Study Instrument: A pre-designed and pre-tested proforma was used to collect information.   PRE ANAESTHETIC EXAMINATION AND PREPARATION    All patients underwent a thorough preanaesthetic evaluation. Patients who met inclusion criteria were enrolled for this study. Written informed consent was obtained.    All the patients were kept nil-per-oral overnight and premedicated with oral diazepam 5 mg on the previous night of surgery. No analgesic was given on the day of surgery before taking to OR. At the pre-operative visit, patients were familiarized with the recording of post-operative pain using a 10-cm visual analogue sale (49) anchored at one end by ―no pain at all ―and at the other end by ―worst pain imaginable.―     PRE-ANAESTHETIC RE-ASSESSMENT  On the day of operation, all the patients were re-assessed in pre-operative anaesthesia room and basal vital data like pulse, blood pressure and SpO2 were recorded.             17   METHOD The patients were randomly allocated into nalbuphine group (Group N), Clonidine group (Group C) or control group (Group Z) using sealed envelope technique into three groups of 33 each, which was opened just before shifting the patient to the operation theatre. 1. Group Z: -2.6 ml of 0.5% hyperbaric bupivacaine and 0.4 ml of Normal saline. 2. Group N: - 2.6 ml of 0.5% hyperbaric bupivacaine and 0.4 ml of 0.8 mg nalbuphine. 3. Group C: - 2.6 ml of 0.5% hyperbaric bupivacaine and 0.4 ml of 60 μg clonidine.   In the operation theatre, an appropriate i.v. access was secured and i.v fluids started. Standard monitoring with electrocardiogram, noninvasive arterial blood pressure (NIBP) and pulse-oximetry was initiated and baseline values were recorded. The patients were administered 2.6 ml of 0.5% bupivacaine hyperbaric with the adjuvant. The sterile drug solution was prepared by an experienced and trained anesthesiologist, who is not involved in intraoperative and postoperative management. Anaesthesia resident doing the study was blinded for the study drug being injected. Under strict aseptic precautions, the subarachnoid blockade was performed with a 26G Quincke spinal needle in the L3-L4 interspace in sitting position. The preloaded sterile drug solution was injected over 10-15 seconds after confirmation of free aspiration of cerebrospinal fluid (CSF). The time at which the preloaded sterile drug solution was completely injected into the sub-arachnoid space was noted as the zero time of the study and all subsequent measurements were recorded from this point. Following the administration of the subarachnoid block, the patients were made to lie down supine. Sensory testing was done by cold swab method using cotton swab and time taken to reach T10 level noted. Motor block assessed using modified Bromage Score.  The time taken to reach modified Bromage 3 was recorded. Intravenous ephedrine 6 mg was administered if the systolic blood pressure reduction was ≥ 20% of the baseline value or if the MAP was ≤60 mm Hg. Intravenous atropine 0.6 mg administered if the HR was ≤50 bpm. Patients did not receive any additional analgesic in intra-operative period while anxious patients were given intravenous midazolam 1mg. The incidence of any adverse 18   effects such as hypotension, bradycardia, shivering, nausea, vomiting, pruritus, respiratory depression and ECG changes were noted. If there was inadequate or failed spinal, the duration of surgery extended more than 120 min or if the patients complains of pain, they were excluded from the study.   All the patients were monitored in the post anaesthesia care unit (PACU) for two hours. In the PACU, inj.Diclofenac 75 mg i.v was administered if the patient complained of pain and had visual analogue scale ≥5. Second line of analgesic inj.tramadol 50 mg slow i.v was administered, if VAS scale did not come below 3, after 30 min administration of inj.Diclofenac 75 mg. If any nausea or vomiting, treated with IV ondansetron 4 mg    Post-operatively, various haemodynamic variables, oxygen saturation and various scores were recorded by a trained attending nurse in the PACU blinded to the injected adjuvant, until complete recovery of the patients from sub-arachnoid blockade.   After SAB, vital parameters - heart rate, SBP, DBP, MAP, and use of ephedrine, atropine were recorded and documented during the first 120 min at intervals of 1min, 3min, 5min, 10min, 15min,20min, 30min,45min,60min,75min,90min,105min, and 120min .   Post operative pain assessment done at the intervals of 4th h, 8th h, 16th h, & 24th h.   Duration of analgesia was taken from the time of intrathecal drug administration to the first supplementation of rescue analgesic when the patient complained of pain or visual analogue scale ≥5.    Definitions of various parameters studied   Time of onset of sensory block: It is defined as time taken from the completion of the injection of the study drug till the patient does not feel the pin prick at T10 level.   19   Time taken for highest level of sensory block: It is defined as the time from the completion of the injection of the study drug to the maximum sensory blockade attained.   Time for two segment sensory regression: It is the time from maximum attainment of sensory block to regression of blockade by two segments Total duration of analgesia: It is the time from drug injection to first request for analgesics. Time of onset of grade III motor blockade: is defined as the time taken from the completion of injection of the study drug till patient develops Bromage-scale 3 Total duration of motor blockade: is the time taken from the time of injection till the patient attains complete motor recovery, Bromage- scale 0.