Finapres arterial pulse wave analysis with Modelflow is not a reliable non-invasive method for assessment of cardiac output.

Non-invasive continuous monitoring of cardiac output could be very useful in clinical care and in research settings, particularly in elderly subjects. We studied whether Finapres arterial pulse wave analysis with Modelflow is a reliable non-invasive method for the assessment of cardiac output in healthy elderly subjects. We compared Modelflow cardiac output (MFCO) with thermodilution cardiac output (TDCO) in 28 healthy subjects, aged 70+/-4 years (mean+/-S.D.). TDCO was measured during right-sided heart catheterization, while MFCO was calculated with Modelflow(R) software from non-invasive arterial Finapres blood pressure, which was measured simultaneously. The two methods were compared using a paired t-test, by Pearson correlation, and by Bland-Altman analysis. TDCO was 6.4+/-1.1 litres/min (mean+/-S.D.) and MFCO was 4.7+/-1.3 litres/min (P<0.001). There was no significant correlation between MFCO and TDCO (r=0.28, P=0.13). Mean difference (bias) was -1.7 litres/min (S.E.M. 0.27 litres/min), with an S.D. (precision) of 1.5 litres/min. The 95% limits of agreement were -4.6 to +1.1 litres/min. In conclusion, non-invasive MFCO values differed significantly from and showed no significant correlation with invasively determined TDCO values in the normal range. Although simple, non-invasive and patient-friendly, the Modelflow method is inaccurate for assessment of cardiac output without invasive calibration.

Recruitment and coaching of healthy elderly subjects for invasive cardiovascular research with right-sided catheterisation.

BACKGROUND AND AIMS: Heart failure is primarily a disorder of the elderly. To investigate a non-invasive method to diagnose heart failure in the elderly, right-sided catheterisation was needed in healthy elderly subjects. We studied the feasibility of recruitment of healthy elderly subjects for this invasive investigation and aimed to identify the factors important for recruitment and for successful participation. METHODS: Healthy subjects, aged >/=65 years, were invited by advertisement in a local newspaper to participate in an invasive study, preceded by extensive medical examination. An experienced research nurse provided coaching and care on an individual basis. Motivation to participate, satisfaction and the expected and perceived burden were assessed with a questionnaire before and after catheterisation. RESULTS: From 180 subjects responding, 53 were invited for screening of whom 38 were included. Cardiovascular examination was the most important reason for participation. The questionnaire showed considerable satisfaction about the information and care given and about participating in the study in general. CONCLUSIONS: Recruitment of healthy elderly subjects for an invasive cardiovascular study is feasible. Individual coaching contributed to the satisfaction experienced. The appointment of an experienced research nurse appears important for successful recruitment and participation of healthy elderly subjects in an invasive cardiovascular study.