Non-invasive foreign gas rebreathing measured cardiac output reliably compared to the direct Fick method, demonstrating a mean bias of 0.1 +/- 0.9 L/min after correction for intrapulmonary shunt.
Observational (n=11)
Does a non-invasive foreign gas rebreathing method provide reliable cardiac output measurements compared to direct Fick and thermodilution in patients with heart failure or pulmonary hypertension?
A new non-invasive foreign gas rebreathing method using an infrared photoacoustic gas analyzer provides reliable cardiac output measurements comparable to thermodilution and direct Fick methods in heart failure patients.
Values of effective pulmonary blood flow (Q(EP)) and cardiac output, determined by a non-invasive foreign gas rebreathing method (CO(RB)) using a new infrared photoacoustic gas analysing system, were compared with measurements of cardiac output obtained by the direct Fick (CO(FICK)) and thermodilution (CO(TD)) methods in patients with heart failure or pulmonary hypertension. In 11 patients, of which three had shunt flow through areas without significant gas exchange, the mean difference (bias) and limits of agreement (+/- 2 S.D.) were 0.6 +/- 1.2 litre x min(-1) when comparing CO(FICK) and Q(EP), and -0.8 +/- 1.3 litre x min(-1) when comparing CO(FICK) and CO(TD). When correction for intrapulmonary shunt flow was applied (i.e. calculation of CO(RB)) in all 11 patients, the bias between CO(FICK) and CO(RB) was 0.1 +/- 0.9 litre x min(-1), primarily because agreement improved in the three patients with significant shunt flow. In the eight patients without significant shunt flow, the agreement between Q(EP) and CO(FICK) was 0.3 +/- 0.9 litre x min(-1). In conclusion, a foreign gas rebreathing method with a new infrared photoacoustic gas analyser provided at least as reliable a measure of cardiac output as did thermodilution. In the absence of significant shunt flow, measurement of Q(EP) itself provides a reliable estimate of cardiac output in heart failure patients. The infrared photoacoustic gas analyser markedly facilitates clinical use of the rebreathing method in general, which makes the method available to a larger group of clinicians working with patients with cardiovascular diseases.
Gabrielsen et al. (Mon,) conducted a observational in Heart failure or pulmonary hypertension (n=11). Non-invasive foreign gas rebreathing method vs. Direct Fick and thermodilution methods was evaluated on Mean difference (bias) and limits of agreement in cardiac output. Non-invasive foreign gas rebreathing measured cardiac output reliably compared to the direct Fick method, demonstrating a mean bias of 0.1 +/- 0.9 L/min after correction for intrapulmonary shunt.