Using Thoracic Electrical Bioimpedance to Measure Stroke Volume and Cardiac Output in Patients Under Spinal Anesthesia for Cesarean Section

The investigators hypothesize that continuously measuring stroke volume (SV) and cardiac output (CO) will 1) reveal hemodynamic instability in a timely manner and alert the physician promptly, 2) provide information for the physician to make the differential diagnosis as to whether the hemodynamic instability was due to vasodilatation or reduction of venous blood return, and 3) lead to appropriate and prompt treatment to improve patient outcome.

-determine the SV and CO and their kinetic change using ICON® to establish a hemodynamic profile of the patient under spinal anesthesia for cesarean section. To determine if using instantaneous measurements of SV and CO to guide patient management improves hemodynamic stability.