Cardiac output by thermodilution and the MostCare system in patients on intra-aortic balloon pump

Introduction

The intra-aortic balloon pump (IABP) is a device used to help the heart pump. During the IABP assistance, significant changes in arterial pressure waveform occur. The so-called pulse contour methods (PCMs) use proper algorithms to analyse the arterial pressure waveform and obtain the cardiac output (CO) [1]. As a consequence, changes in pressure waveform in patients on IABP may affect the reliability of different PCMs. The aim of this study was to investigated the reliability of a new PCM, the MostCare powered by the pressure recording analytical method (PRAM) (Vytech Health, Laboratoires Pharmaceutiques Vygon, Ecouen, France), by comparing its CO values (PRAM-CO) with those determined by bolus thermodilution (ThD-CO) during aortic counterpulsation.

Methods

Eight patients requiring hemodynamic support with an IABP after coronary surgery were studied. A thermodilution pulmonary artery catheter was inserted. To compute the CO from the analysis of the radial artery pressure waveform, the MostCare was connected via a cable to the monitoring system (Hewlett Packard, Andover, MA, USA). The comparisons of CO values by the two techniques were carried out at four different IABP settings: 1:1, 1:2; 1:3, and 1:4. Pearson's correlation and Bland–Altman analysis were applied. Percentages of error were also calculated.

Results

A total of 64 ThD-CO and PRAM-CO measurements were evaluated. ThD-CO values ranged from 2.4 to 6.8 l/min; PRAM-CO values ranged from 2.6 to 6.2 l/min. Mean ThD-CO values ranged from 4.0 ± 0.8 to 4.3 ± 0.9 l/min. Mean PRAM-CO values ranged from 3.9 ± 0.7 to 4.2 ± 0.8 l/min. At each IABP setting: (1) correlations between the two methods were 0.90, 0.87, 0.88, and 0.86; (2) mean biases were 0.11, 0.05, 0.10, and 0.12; and (3) percentages of errors were 19%, 20%, 19%, and 18%.

Conclusion

Bolus thermodilution and MostCare showed a good agreement at each time of the study. Although the IABP altered the arterial pressure wave profile this did not seem to affect the capability of the MostCare to adequately estimate the CO. This new device seemed to perform suitably in patients assisted with the IABP.