Mini-bolus technique for thermodilution cardiac output measurements.

摘要

A composite catheter for in vivo fluid injection is provided in which a thin tube (32) is located within a lumen (18) of a conventional catheter (10). The thin tube has a small diameter inner passage (44) for the in vivo injection of a fluid to be applied through a port (48) in the catheter wall (12) into the blood stream. A sensing device, such as a thermistor (50), is mounted on the catheter downstream of the port to measure changes in the properties of the fluid resulting from fluid injection for thermodilution applications. The space (45) within the lumen (18) insulates the fluid from the catheter environment and the small bore inner passage (44) reduces residual fluid permitting small fluid injections that accommodate frequent injection measurements.