<prompt> Which of the following is not useful in measuring cardiac output?Transthoracic echocardiogramCentral venous catheterThermodilution pulmonary catheterContinuous cardiac output pulmonary catheter  <response>: Ans. B. Central venous catheter Central venous catheter alone is not useful for measuring cardiac output. Various methods to measure cardiac output are as follows:- Pulmonary artery flotation catheter PAFC: Use dye dilution and thermodilution techniques bolus and continuous thermodilution cardiac output monitoring- Arterial waveform analysis- Thoracic electrical bioimpedance- Fick partial rebreathing method uses CO2 - Aortic Doppler transesophageal and transcutaneous- Point-of-care Echo transthoracic as well as transesophageal--LVOT is analyzed for cross-sectional area CSA and velocity time integral VTI. Cardiac output CO is measured by the formula COCSAxVTIxHR- Lithium dilution uses peripheral vein- Combined lithium dilution and pulse contour analysis 