Study protocol
Bradycardia, nausea, ’, Postoperative pain, pain, pruritus, NRS pain, hypotension, Hypotension, height of sensory block
HYPERTENSION, GROUP B
Based on a computer-generated random number sheet, patients were randomly allocated into Group B (intravenous administration of normal saline plus continuous intravenous pump of butorphanol) or Group P + B (intravenous administration of palonosetron plus continuous intravenous pump of butorphanol). An investigator (Hui Wu) who did not participate in any anaesthetic care or data collection opened the sealed envelopes, which contain the group assignments, and prepared the drug according to the group allocation.All patients fasted for over 6 h and received no premedication. On arrival in the operating room, basic vital sings, including pulse oximetry, non-invasive blood pressure, and electrocardiogram were continuously monitored. After a brief settling period, baseline resting BP of the patient will be recorded by calculating the mean of three consecutive measurements with a difference of not more than 10%. Combined spinal-epidural anaesthesia procedure was performed in the left lateral position of patient. First, under local anaesthesia, epidural puncture was performed at the estimated L3-4 vertebral interspace with a 16-G needle, the arrival of the needle tip into the epidural space was identified by the method of ‘loss of resistance to air’. Second, spinal puncture was conducted with a 27-G pencil-tip needle. After ascertaining free flow of clear cerebrospinal fluid from the pencil-tip needle, 15 mg of hyperbaric ropivacaine diluted with 10% dextrose was slowly injected over 15 s. If there is no outflow of CSF from the spinal needle, it will be removed, the direction of the epidural needle will be adjusted and the spinal needle will be reinserted. If there is still no CSF outflow, both needles will be removed and the CSE procedure will be repeated. If the second attempt is also unsuccessful, the case will be withdrawn from the study and further clinical care will be at the discretion of the attending anaesthesiologist. At the same time of ropivacaine injection, 5 mL/kg of warmed lactated Ringer’s solution was infused for 20 min and then slowed down to maintain the patency of veins. Simultaneously, phenylephrine (0.5 µg/kg/min) was given intravenously to prevent hypotension. An epidural catheter was placed into the epidural space cephalally for 3–4 cm. The patients were then returned to the supine position with left uterine displacement. The height of sensory block was evaluated by assessing the loss of anterior midline needling sensation. Surgery was permitted to start when sensory block height reached higher than T6. Hypotension, defined as systolic blood pressure < 90 mmHg or a drop in systolic blood pressure by more than 20% from baseline, was treated with a 50 μg bolus of intravenous phenylephrine. Reactive hypertension, defined as an increase in systolic blood pressure by over 20% from baseline, was treated by immediately stopping the infusion of phenylephrine. Bradycardia (heart rate <50 beats/min) without hypotension was managed by stopping the infusion of phenylephrine, which was restarted when the heart rate increased back to over 50 beats/min. Bradycardia with hypotension was treated with an intravenous injection of 0.5 mg atropine. If nausea occurred during the operation, dexamethasone 5 mg was given intravenously.At skin closure, 2 mg of morphine (diluted to a total volume of 2 mL), followed by a 1 mL normal saline flush, was injected At each time point (6 h, 12 h, 24 h, 48 h) after epidural morphine injection, the severity and location of pruritus and pain were recorded. Postoperative pain was evaluated by NRS pain score (a 10 cm linear scale, with 0 and 10 labelled as ‘no pain’ and ‘worst pain imaginable’, respectively) [