Can Hypotension Episodes that were not Identified in the Non-Invasive Blood Pressure be Detected during Cesarean Section? A Randomized Controlled Trial

BACKGROUND: Neuraxial anesthesia is a commonly used technique for cesarean section (C/S) because of its simplicity, rapid onset of action, and the requirement of lower doses of anesthetic agents with the lack of uteroplacental transfer. However, this type of anesthesia often causes sudden onset of hypotension, and its pathogenesis is not yet clearly understood. AIMS: To evaluate the efficacy and necessity of continuous noninvasive arterial pressure (CNAP) by comparing it with non-invasive blood pressure (NIBP) in order to understand whether it has advantages over oscillometric technique for detection of hypotensive episodes in healthy pregnant women who underwent C/S under neuraxial anesthesia. STUDY DESIGN: A randomized controlled study. METHODS: This prospective study evaluated healthy pregnant women at term who were scheduled for elective C/S under spinal anesthesia. Subjects were randomly assigned into two groups to receive either CNAP and NIBP, or only NIBP. A 30% decrease in systolic blood pressure from either baseline or the measured values in the first two minutes, or if the systolic blood pressure was less than 90 mmHg, is considered hypotension. Pre-, peri-, and postoperative specifications; newborn characteristics; and complications were recorded and compared. RESULTS: A total of 106 individuals were enrolled in the study, with 53 parturients in each group. They were equally distributed in both groups (P > 0.05). The oscillometric method failed to detect hypotension in 8 out of 29 pregnant women who were noted to be hypotensive with CNAP. The number of hypotension events detected was higher, and the time to detection of the first episode of hypotension was shorter in the CNAP group (P > 0.05). A total of four newborns required intensive care unit treatment, one of whom needed mechanical ventilator support, all born to mothers in the CNAP group (P > 0.05). CONCLUSION: Continuous non-invasive arterial pressure in detecting hypotensive episodes does not provide an additional advantage to healthy pregnant women undergoing elective cesarean section.