Comparison of estimation of cardiac output using an uncalibrated pulse contour method and echocardiography during veno-venous extracorporeal membrane oxygenation

Introduction:

During veno-venous extracorporeal membrane oxygenation, cardiac output monitoring is essential to assess tissue oxygen delivery. Adequate arterial oxygenation depends on the ratio between the extracorporeal pump blood flow and the cardiac output. The aim of this study was to compare estimates of cardiac output and blood flow/cardiac output ratios made using an uncalibrated pulse contour method with those made using echocardiography in patients treated with veno-venous extracorporeal membrane oxygenation.

Methods:

Cardiac output was estimated simultaneously using a pulse contour method (MostCareUp; Vygon, Encouen, France) and echocardiography in 17 hemodynamically stable patients treated with veno-venous extracorporeal membrane oxygenation. Comparisons were made using Bland–Altman and linear regression analysis.

Results:

There were significant correlations between cardiac output estimated using pulse contour method and echocardiography and between blood flow/cardiac output estimated using pulse contour method and blood flow/cardiac output estimated using echocardiography (r = 0.84, p < 0.001 and r = 0.87, p < 0.001, respectively). Bland–Altman analysis showed a good agreement (bias −0.20 ± 0.50 L/min) and a low percentage of error (25%) for the cardiac output values estimated by the two methods. The bias between the blood flow/cardiac output ratios obtained with the two methods was 5.19% ± 12.3% (percentage of error = 28.1%).

Conclusions:

The pulse contour method is a valuable alternative to echocardiography for the assessment of cardiac output and the blood flow/cardiac output ratio in patients treated with veno-venous extracorporeal membrane oxygenation.

Carotid intima–media thickness: a suitable alternative for cardiovascular risk as outcome?

BACKGROUND

Surrogate markers for cardiovascular disease might be of great value in observational research, clinical trials, and clinical practice. Carotid intima-media thickness (CIMT) is probably the most commonly used marker for atherosclerotic disease as an alternative for cardiovascular morbidity and mortality. A suitable marker for atherosclerosis, however, should meet several criteria before it can be validly used.

METHODS AND RESULTS

We reviewed the literature following a set of criteria for a surrogate marker. These include a comparison with a 'gold standard'; adequate reproducibility; cross-sectional relations with established risk factors and prevalent disease; relations with severity of atherosclerosis elsewhere in the arterial system; relations with the occurrence with future events; ability for a biomarker to change over time; ability to be affected by interventions over time; and relations between change over time in biomarker level and change in risk. A large number of studies from a variety of populations provide evidence for the validity of CIMT as a suitable measure of atherosclerotic disease. Data on the relation between change in CIMT and change in risk, however, is much sparser.

CONCLUSION

CIMT progression meets the criteria of a surrogate for cardiovascular disease endpoints and may be considered as a valid alternative for cardiovascular events as outcome. Further studies should examine the association between changes in CIMT and changes in risk for future events.