OBJECTIVE: To evaluate the reliability of a new noninvasive method for the assessment of cardiac output with the partial carbon dioxide rebreathing technique. METHODS: This technique was applied to patients undergoing heart surgery. Values of cardiac index obtained with this equipment were compared with the artero-venous CO2 gradient, a reliable index of cardiovascular status. Positive and negative predictive values of the test were assessed. RESULTS: A total of 21 simultaneous measurement of the cardiac index and of the artero-venous CO2 gradient were obtained. The positive predictive value of the test was 67% while the negative predictive value was 100%, indicating that a normal value of cardiac index recorded with the rebreathing technique predicts with a good reliability a normal cardiovascular state. CONCLUSIONS: Working through a series of mathematical algorithms, accuracy in the computation of cardiac output can be decreased with this equipment; however, this limitation seems to be outweighed by the simplicity and noninvasive nature of the methods.
OBJECTIVE: To evaluate the reliability of a new noninvasive method for the assessment of cardiac output with the partial carbon dioxide rebreathing technique. METHODS: This technique was applied to patients undergoing heart surgery. Values of cardiac index obtained with this equipment were compared with the artero-venous CO2 gradient, a reliable index of cardiovascular status. Positive and negative predictive values of the test were assessed. RESULTS: A total of 21 simultaneous measurement of the cardiac index and of the artero-venous CO2 gradient were obtained. The positive predictive value of the test was 67% while the negative predictive value was 100%, indicating that a normal value of cardiac index recorded with the rebreathing technique predicts with a good reliability a normal cardiovascular state. CONCLUSIONS: Working through a series of mathematical algorithms, accuracy in the computation of cardiac output can be decreased with this equipment; however, this limitation seems to be outweighed by the simplicity and noninvasive nature of the methods.