The analgesic efficacy of a low dose of bupivacaine plus fentanyl versus a conventional dose of bupivacaine plus fentanyl for subarachnoid anaesthesia during caesarean section

The patients that met the inclusion criteria were assigned to one of the two comparison groups by a random number table: 1. Group 1 received 7.5 mg of hyperbaric bupivacaine 0.5% plus 25 µg of fentanyl 2. Group 2 received 12.5 mg of hyperbaric bupivacaine 0.5% plus 25 µg of fentanyl For both groups, the total solution volume was 3 ml. Group 1 was supplemented with 1 ml of saline. The drug was prepared by a chemical pharmacy and a second person was designated to the group to make the markings on the syringes. Neither the anaesthesiologist who performed the procedure and readied the syringe nor the research team knew the drug supplied. On admission to the surgical ward, patients were monitored with non‐invasive blood pressure (NIBP), electrocardiogram (ECG) at D II derivation, heart rate measurements, pulse oximetry, and respiratory rate measurements and supplemental oxygen was administered via a nasal cannula at 2 liter per minute. All patients received load of 7 ml / kg of 0.9% normal saline solution (SSN) or Ringer?s lactate in 10‐15 minutes. Patients were placed in a sitting position and a 26 G Quincke needle was inserted at the L3‐4 interspace by a medial or paramedial approach. Asepsis was ensured by performing antisepsis at the lumbar region. Clear cerebrospinal fluid was injected with an anesthetic solution at a rate of 1 ml/25 s bubbling. After the injection, the position of the needle was confirmed by aspiration of 0.5 ml of CSF and re‐injected. The patient was immediately accommodated in a supine neutral position by passing the uterus 15 degrees to the left using a wedge. Maintenance was performed with 0.9% SSN or Ringer's lactate at 10 ml / kg / h. If the mean arterial pressure decreased by more than 20% compared to baseline levels or systolic blood pressure reached levels below 90 mmHg, ephedrine was administered by IV at a dose of 5‐10 mg. If this dose failed to anesthetise, etilefrine or phenylephrine was administered at a dose of 50‐100 µg. If the heart rate reached levels below 50 beats per minute, then the patient was given atropine at a dose of 0.01 to 0.02 mg/k. 1. Patient and obstetrician satisfactions were defined as satisfied, moderately satisfied, very satisfied or unsatisfied 2. Postoperative pain was evaluated at two and six hours after operation by a verbal numerical scale (0‐10, with 0 indicating no pain and 10 indicating excruciating pain). If the patient indicated a number greater than 5, a 4 mg / k dose of morphine was added via IV. 1. The maternal side effects 2. Intraoperative pain 3. Onset time for motor and sensory block, motor block level, maximum level of sensory block, patient and obstetrician satisfaction. The assessment of sensory block was made by prick and thermal sensitivity, while motor block was evaluated using the Bromage scale 3.1. I‐patient moves only the legs, 3.2. II‐ Patient moves only the feet 3.3. III‐ The knees flex 3.4 IV‐patient raises and extends the legs . This evaluation was performed at 5, 10, and 15 minutes with the medicine cord. 4. For transitional analgesia, 50 mg / k doses of dipyrone were administered intraoperatively. If anesthetic effects were not properly observed (absence of sensory and motor block), the procedure was repeated with the same dose. In cases of inadequate anesthesia (presence of surgical pain after 20 minutes) or cases in which the patient?s discomfort or inconvenience was related to manipulation of the uterus, the patient was administered a fentanyl bolus of 50 µg then two bowls by IV. If full pain management was not achieved, the general anesthetic technique was used.