Which statement correctly describes the Injectate Lumen Port?

• A. It is used for injectate delivery for thermodilution CO measurements
• B. It inflates the balloon
• C. It connects to the transducer for PA pressures
• D. It samples mixed venous blood

Answer: (A)

The injectate lumen port is the channel on the pulmonary artery catheter used to deliver the injectate for thermodilution cardiac output measurements. In thermodilution, a bolus of cold saline is injected rapidly through this port into the right atrium and then into the pulmonary artery, while a downstream temperature sensor records the temperature change. The resulting thermodilution curve is analyzed to determine cardiac output. This port is dedicated to injection, not for inflating the balloon, connecting to the PA pressure transducer, or sampling blood—balloon inflation uses a separate lumen, PA pressures come from the pressure/transducer lumen, and mixed venous blood is drawn from a sampling port.