Clinical utility of preoperative bilateral carotid artery corrected flow time (FTc) and carotid artery pulsatility index(PI) for predicting hypotension after spinal anesthesia in parturient undergoing elective caesarean section in tertiary care hospital

The parturient scheduled for an elective cesarean section under spinal anesthesia will be recruited after obtaining informed and written consent one day prior to surgery. After being transferred to the operating room, standard ASA monitors will be attached to the parturient. Baseline values of heart rate, systolic blood pressure, diastolic blood pressure, and mean arterial pressure will be recorded with the table in a left lateral tilt at 15-20 degrees. A high-frequency linear ultrasound probe will be placed over the common carotid artery, approximately 2 cm proximal to the carotid bifurcation, to obtain Doppler waveforms. These measurements will be taken with the table in a left lateral tilt at 15-20 degrees. The data obtained from each side will be used to calculate the corrected flow time interval (FTc) and pulsatility index (PI).Following the ultrasound assessments, the parturient will be positioned for spinal anesthesia, and 0.5% hyperbaric bupivacaine (1.8-2 ml) will be administered. The parturient will then be turned supine with a wedge placed under the right hip. The level of sensory block will be confirmed by the response to cold touch. Systolic blood pressure will be measured at one-minute intervals after spinal anesthesia until the delivery of the baby. Hypotension will be defined as a decrease in systolic blood pressure to less than 100 mmHg or a fall of more than 80% from baseline. Any hypotension will be treated with intravenous vasopressors, and the details of the treatment will be recorded. The obtained data will be analyzed to identify any correlation with post-spinal hypotension.