Swan Ganz Catheter is used to measure –
**Core Concept**
The Swan-Ganz catheter, also known as a pulmonary artery catheter (PAC), is a type of catheter used to measure various hemodynamic parameters in critically ill patients. It is inserted through a peripheral vein and advanced into the pulmonary artery to obtain direct measurements of cardiac output, pulmonary artery pressure, and other related parameters.
**Why the Correct Answer is Right**
The correct answer is to measure cardiac output. The Swan-Ganz catheter is equipped with a thermal dilution technique, which involves injecting a cold saline bolus into the right atrium while measuring the temperature change in the pulmonary artery. This temperature change is then used to calculate the cardiac output. The catheter also has a pressure port to measure the pulmonary artery pressure, which is a reflection of the left atrial pressure and left ventricular preload.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because while the Swan-Ganz catheter can measure cardiac output, it is not primarily used to measure cardiac output in the context of cardiac surgery or coronary artery bypass grafting.
**Option B:** This option is incorrect because the Swan-Ganz catheter is not typically used to measure central venous pressure (CVP). While CVP can be measured using a central venous catheter, the Swan-Ganz catheter is used to measure pulmonary artery pressure and cardiac output.
**Option C:** This option is incorrect because the Swan-Ganz catheter is not used to measure mixed venous oxygen saturation (SvO2). While mixed venous oxygen saturation can be measured using a central venous catheter, the Swan-Ganz catheter is used to measure pulmonary artery pressure and cardiac output.
**Clinical Pearl / High-Yield Fact**
A key clinical application of the Swan-Ganz catheter is in the management of patients with cardiogenic shock, where it can be used to guide fluid therapy and inotropic support. The PAC can also be used to monitor patients with severe left ventricular dysfunction or those undergoing cardiac surgery.
**Correct Answer:** C. Cardiac output.