Endotracheal cardiac output monitor

Background: The endotracheal cardiac output monitor (ECOM) is a new device that uses an endotracheal tube with multiple electrodes to measure cardiac output (CO), It measures the changes In electrical impedance caused by puls atile blood flow in the aorta. The system was tested for safety and efficac y in 10 swine. Methods: Swine (60-80 kg) were chronically instrumented with a transit time flow probe on the ascending aorta and vascular occluders on the vena cava and pulmonary artery After a minimum recovery of 4 days, the animals were a nesthetized and intubated with an ECOM endotracheal tube. CO measurements f rom the ECOM system were compared to transit time flow probe measurements u sing linear regression and Bland-Altman analysis. Three different inotropic states were studied: (1) baseline; (2) increased (dobutamine); and (3) dec reased (esmolol). CO was changed at each inotropic state by impeding left v entricular filling with the vena cava or pulmonary artery occluders. CO val ues between 0 and 15 l/min were studied. Pigs were studied for 24 h consecu tively. Results: There was no deterioration of the impedance signal with time and n o tracheal injury from the ECOM electrodes. There is a linear relationship between the ECOM and transit time flow probe CO between 0 and 15 l/min (slo pe = 0.94; intercept = 0.15 l/min; R-2 = 0.77), The mean difference between the two measures (bias) is 0.15 l/min and the SD is 1.34 l/min, The limits of agreement are -2.53 to 2.82 l/min, Conclusion: Endotracheal CO monitor is a promising technology that needs fu rther evaluation in clinical trials.