Predictability of Preoperative Carotid Artery Corrected Flow Time for Hypotension After Spinal Anesthesia in Patients Undergoing Cesarean Section

The purpose of this study was to investigate the incidence of hypotension after spinal anesthesia in patients undergoing cesarean section as predicted by preoperative carotid artery corrected flow time measured by Doppler ultrasound. Before entering the operation room, Two inspectors perform two measurements of carotid artery corrected blood flow time respectively, and an average of the four measurements is calculated and analyzed. At this time, the patient's posture is supine, and the head is turned about 30 degrees to the left. Corrected blood flow time (FTc) is measured using carotid ultrasound as previously described by Blehar and colleagues. Corrected blood flow time is calculated by Bazett's formular and Wodey's formular by evaluating a single cycle after several successive cycles have reached a stable and acceptable quality level. The occurrence of hypotension is recorded from the spinal anesthetic injection until the fetus is delivered. The definition of hypotension after spinal anesthesia is that the systolic blood pressure drops to 80 mmHg, less than 75% of the baseline value, or even if it does not meet the former criteria, symptoms that are consistent with hypotension (dizziness, dizziness, dyspnea, nausea or vomiting).