Comparison of pulmonary artery and arterial thermodilution cardiac output in critically ill patients

Objective: We studied the agreement between cardiac output measurements via pulmonary artery thermodilution [CO(PA)], regarded as the current clinical gold standard, and aortic transpulmonary thermodilution [CO(AORTA)]. Design: Prospective clinical study. Setting: Surgical intensive care unit of a university hospital. Patients: 37 patients with sepsis or septic shock (n = 34) and subarachnoid haemorrhage (n = 3). Measurements and results: We analysed 449 simultaneous cardiac output measu rements. All patients were deeply sedated and mechanically ventilated in a pressure controlled mode. Each patient received a 7.5-F five-lumen pulmonar y artery catheter and a 4-F aortic catheter with an integrated thermistor. The thermistors of the two different catheters were connected to one comput er system (COLD-Z021, Pulsion Medical Systems, Munich, Germany). Linear reg ression analysis revealed: CO(AORTA) = 0.96 . CO(PA) + 1.02 (l/min) (r = 0. 97, p < 0.0001). CO(AORTA) was consistently higher than CO(PA) with a bias of 0.68 (l/min) and a standard deviation of 0.62 (l/min). Conclusion: Cardiac output derived from aortic transpulmonary thermodilutio n is suitable for measurement in the intensive care unit. Measurements of C O(AORTA) are consistent with, but slightly higher than, those obtained from pulmonary artery thermodilution.