OBJECTIVE: To assess the accuracy of room-temperature thermodilution cardiac output measurements from the venous infusion port. DESIGN: Central venous port cardiac output measurements were compared with venous infusion port measurements in 48 right-heart catheters. INTERVENTION: Three 10-mL injections of 5% dextrose in water were made through each port. The order of port injection was random. RESULTS: The cardiac outputs were 5.8 +/- 1.8 L/min from both ports, with no difference between ports (paired t test). CONCLUSION: Room-temperature thermodilution cardiac output determinations from the venous infusion port can be used in place of central venous port cardiac outputs if the central venous port becomes nonfunctional.