Study protocol
Bradycardia, bradycardia, loss of pinprick sensation, Hypertension, hypotension
HYPERTENSION, UTERINE ATONY
Based on a randomized number sheet generated by a research assistant using an online randomization generator (None of the patients received any premedication. In the waiting room, peripheral access was created using an 18 G intravenous cannula inserted into the left upper limb vein. Upon arrival at the operating room, a standard monitoring procedure, which included a non-invasive blood pressure cuff, electrocardiography leads, and a pulse oximeter, was applied to record the patients’ vital signs. The baseline systolic blood pressure (SBP) and heart rate (HR) were calculated as the means of three readings, which were consecutively measured at 3-min intervals, after the patient was relaxed. Oxygen was delivered by a nasal catheter at a rate of 3 L per minute. There was no prehydration.With the patient positioned on a left lateral position, the combined spinal-epidural technique was performed using the needle-through-needle procedure at the established L3-L4 disc space, which was detected by palpation. After detecting cerebrospinal fluid (CSF) efflux, 15 mg hyperbaric ropivacaine combined with 5 μg sufentanil were injected into the subarachnoid space over 20 seconds. Immediately after intrathecal injection, 0.5 μg/kg/min phenylephrine [According to institutional standards, hypotension was defined as a fall of SBP ≥ 20% from its baseline value and to an absolute value of SBP < 90 mmHg. Hypertension was defined as an absolute value of SBP > 140 mmHg. Bradycardia was defined as the HR < 55 beats per minute (bpm). If hypotension was accompanied by a rapid HR (> 90 bpm), 100 μg phenylephrine were administered by an intravenous (i.v.) injection. If hypotension was not accompanied by a rapid HR, 5 mg ephedrine were administered through i.v. injection. If bradycardia co-occurred with hypotension, it was treated by an i.v. injection of 0.5 mg atropine. If not, phenylephrine infusion was paused and restarted when the HR > 55 bpm.Surgery was not permitted until the sensory block level (by asking the patient for the loss of pinprick sensation) reached T6 dermatome or higher. All cesarean procedures were accomplished by the same group of surgeons with more than 10 years of obstetric experience. After neonatal delivery and umbilical cord clamping, 3 IU oxytocin were slowly intravenously injected over 15 seconds, followed by an infusion of 50 mL/h oxytocin (whose dose depended on the patient’s group) to prevent uterine atony. Until 20 minutes after umbilical cord clamping, the adequacy of UT was assessed by the leader of the obstetric group at 3-min intervals [