The purpose of this clinical trial is to demonstrate that cardiac output (CO) as determined with the Clinical Platform (Model:EV1000A, Software Version:1.9) in a noninvasive manner is comparable to CO as determined by Pulmonary Artery Catheter (PAC) thermodilution (TD). The results of this study may be used for registration and regulatory submissions.

Inclusion Criteria:

• Subjects must be at least 18 years of age
• Subjects provide written informed consent prior to trial procedures
• Subjects' height and weight must be accurately obtained prior to study start.

Exclusion Criteria:

• Aortic or tricuspid valve regurgitation
• Aortic stenosis or aneurysms
• Cardiac rhythm disorder
• Patients with extreme contraction of the smooth muscle in the arteries and arterioles in the lower arm and hand, such as may be present in patients with Raynaud's or Buerger's disease or with extremely cold hands
• Inability to place the finger cuff appropriately due to subject anatomy or condition
• Known pregnancy
• Patients being treated with an intra-aortic balloon pump
• Patient is currently participating in an investigational drug or another device study that clinically interferes with the study endpoints
• Intracardiac shunt

Patients undergoing elective major cardiothoracic surgery with an indwelling PA catheter. The surgical intervention includes, but is not limited to, mitral valve surgery or coronary artery bypass grafting.