Serial echocardiographic measurements of cardiac output after spinal anesthesia for scheduled cesarean delivery in healthy patients: a prospective observational study.

BACKGROUND

Results of studies assessing cardiac output during cesarean delivery are conflicting. Transthoracic echocardiography has been applied in obstetric anesthesia research and clinical practice. We used transthoracic echocardiography to evaluate changes in cardiac output after spinal anesthesia for scheduled cesarean delivery in healthy patients.

METHODS

This single-arm, prospective observational study was conducted on 60 patients with full-term, singleton pregnancy. Patients received 1000 mL crystalloid coload over 10 minutes; rescue repeated ephedrine bolus for systolic blood pressure <90% (3 mg), 80% (5 mg), and 70% (10 mg) of baseline, respectively; and 10 IU/30 minutes oxytocin infusion. Transthoracic echocardiography was performed at baseline, 10 minutes after intrathecal injection, immediately after delivery, and 1 hour after intrathecal injection. Primary outcome was serial changes in cardiac output over time after spinal anesthesia. Secondary outcomes were serial changes in stroke volume and heart rate, number of patients receiving ephedrine, and incidence of hypotension, severe hypotension, bradycardia, and nausea/vomiting.

RESULTS

Mean ± standard devliation baseline cardiac output, stroke volume, and heart rate was 5601 ± 1430 mL/min, 61 ± 14.8 mL, and 92 ± 7.8 beats/min, respectively. Cardiac output and stroke volume increased over time lasting for 1 hour after intrathecal injection. Heart rate increased after spinal anesthesia and after delivery and returned to near baseline 1 h after intrathecal injection.

CONCLUSIONS

Using crystalloid coload, ephedrine boluses, and oxytocin infusion, cardiac output increased (accompanied with parallel increase in stroke volume) after spinal anesthesia, with highest values immediately after delivery. Transthoracic echocardiography was feasible and applicable for hemodynamic monitoring during cesarean delivery.