Continuous measurement of cardiac output with the electrical velocimetry method in patients under spinal anesthesia for cesarean delivery.

In this study, we aimed to continuously measure cardiac output (CO) with the electrical velocimetry (EV) method and characterize the hemodynamic profile of patients undergoing spinal anesthesia for elective cesarean delivery (CD), and to discuss the potential benefit of using real time CO monitoring to guide patient management. Forty-two patients scheduled for elective CD under spinal anesthesia were enrolled in this observational study. A non-invasive CO monitor incorporating the electrical velocimetry algorithm, ICON(®) (Cardiotronic(®), La Jolla, California, USA), was used to measure CO and stroke volume (SV) continuously. Peripheral venous pressure was measured intermittently at pre-defined time points. Systemic vascular resistance was calculated retrospectively after completion of the study. Hemodynamic changes at pre-defined time points and caused by phenylephrine administration were analyzed. Hypotension (MAP reduction more than 20% from baseline values) occurred in 71.1% of patients after spinal anesthesia, while the coinstantaneous CO was increased ≥20% from baseline in the majority of patients (76.3%) at the same time. Significant increase in CO took place at 3-2 min before the administration of phenylephrine bolus. Treatment of hypotension with phenylephrine was associated with significant decrease in CO. Continuous CO monitoring with EV enables clinicians to determine CO and SV changes prior to onset of hypotension and to better understand patients' hemodynamics. It is an important addition to the current monitoring. The benefit of routinely using this technique remains to be determined in term of the patient outcomes.