1) What does “MostCare” stand for? What does “P.R.A.M.” stand for?

MostCare is the name of our device, it stands for MOnitor of STroke Volume and CARdiac Efficiency; P.R.A.M. is the algorithm inside the device: it stands for Pressure Recording Analytical Method.

2) Which disposable devices do I need to buy in order to use MostCare? Do I need to change my actual arterial catheters or my pressure transducers?

MostCare does not need any dedicated disposable! MostCare works taking the pressure signal by any arterial catheter (any brand!) and by any pressure transducer (any brand!).

3) How can I provide MostCare with the arterial signal?

It’s your choice. You can link MostCare to the arterial pressure transducer or to your main monitor. MostCare is compatible with most of the pressure transducer/monitor today on the market. Just tell your local Sales Representative the device you are using today: we will provide you MostCare with the proper, compatible monitor/transducer cable.

4) How long does it take to prepare MostCare before using it?

MostCare is totally plug-and-play. To perform haemodynamic monitoring in your patient, just connect it to your main monitor or directly to the arterial pressure transducer. In 5 short steps, you will be able to see a CO value with all the other major haemodynamic parameters. Total time: less than 2 minutes.

5) In which artery should I place the arterial catheter to use MostCare?

MostCare is totally versatile. Both radial or femoral arterial pressure curve can be precisely analyzed when all haemodynamic parameters need to be visualized.

6) Why is it so important MostCare’s unique ability to sample arterial signal at 1000Hz?

Arterial signal exiting from the pressure transducer is analogical, it means that it is continuous. To analyze an arterial curve, the analogical signal has to be sampled. Sampling process consists in detecting some subsequent points so to reconstruct arterial continuous shape. Sampling frequency indicates how many subsequent values are registered and elaborated. MostCare, differently from other monitors on the market, samples the analogical signal at 1000Hz (versus 100-200Hz). Such precise curve detection permits to estimate in a better way the impedance of the cardiovascular system and so, to obtain a more precise value of the haemodynamic parameters.

7) MostCare samples the signal at 1000Hz, but it can take the signal from a monitor working at 100Hz: how is it possible?

Be careful! In order to obtain the signal, we connect MostCare with the ANALOG OUTPUT connector of the monitor: it means that the signal is taken before being sampled at 100Hz! MostCare receive the analogical signal both from the main monitor or from the catheter transducer and then it samples it at 1000Hz.

8) What does MostCare need to provide accurate calculations?

a) As PRAM works solely on arterial pressure curve analysis, the prerequisite to have reliable calculations is to have a good quality of the arterial pressure signal; compromised waveforms due to an under-dumped or an over-dumped signal can result in wrong CO value. We recommend verifying with the square wave test the quality of the arterial pressure curve. A dP/dt value higher than 1,7 can indicate that the pressure signal is resonant and you should better dump the signal.

b) To calculate Stroke Volume from Pulse Contour wave analysis, the area underneath the systolic portion of arterial pulse should be divided for the impedance. The diastolic pressure represents the start point of arterial curve area to be considered, while the dicrotic pressure is the end of it. This is why it is essential that the dicrotic notch be correctly recognized and evidenced by the device (vertical green line). When the typical pulses shape is recognized and the vertical green line in MostCare screen coincide with the dicrotic notch, you can trust the parameters. Even in case of moderate arrhythmias, fibrillations and valves pathologies (both insufficiency and stenosis), when the arterial pulse and the dicrotic notch are appropriately recognized by MostCare, all the hemodynamic parameters can be considered reliable.

1) Can I trust MostCare in case of atrial fibrillation? And in case of aortic valve insufficiency?      

Yes, until the dicrotic notch is visible and correctly indicated by the green line. No particular settings are necessary. Just remember that in case of atrial fibrillation dynamic fluid responsiveness parameters are not trustable as their variability is not related to venous return only but basically to heart contractions.

2) Can I use MostCare when the patient is treated with intra-aortic balloon pump (IABP)?

Yes. You only have to set the device accordingly; "IABP" option should be indicated since the beginning of the monitoring. Visually inspect that the dicrotic notch is well detected. MostCare performs well both when IAPB is settled with a beat ratio of 1:1 or less (1:2, 1:4, 1:8). The parameters has the same reliability as the one in a non-IABP assisted patient; SV, CO, dP/dt and CEE visualized values are referred to effective patient's heart.

3) Can I use MostCare when the patient is haemofiltrated? And with a Ventricle Assisted Device?

Yes. In this case, the mechanical device inserted in the circulatory system impacts in arterial wave; as the external device is characterized from a particular rigidity, the arterial curve could suffer of some effects similar to the one occurring in case of a resonant catheter. dP/dt value could appear particularly high (>1.7). To eliminate possible artifacts, select “DISTURBED LINE”; SV and CO measurements will be correctly calculated.

4) Can I use MostCare to monitor paediatric patients?     

Yes. MostCare doesn't use normogram-based, precalculated data but it really considers the monitored patient; paediatric patients can effectively be monitored thanks to PRAM algorithm. Just select "paediatric patient" in MostCare setting when you need to observe a patient weighting less than 18-20 kg.

1) What is Pulse Contour Method (PCM)?

PCM is a theory postulated by O.Frank in 1899 [1]; O.Frank first found that pressure rise during systole was related to systolic filling of aorta and proximal large arteries; many authors later confirmed this relation.

O.Frank perceived that SV was the result of the pulsatory systolic component of arterial wave divided by the impedance Z(t). With those days science findings, it was not possible to measure the dynamic Z(t) value. He resigned himself to proceed with some simplifications: PCM could lead only to an approximated SV. PRAM finally concretizes O.Frank first purpose.

2) How can MostCare calculate Stroke Volume (SV) without the need of an external calibration or preestimated data?

As we already know, SV is calculated dividing an area under the systolic phase of the pressure waveform (A) by an impedance Z(t) changing over time. The way in which P.R.A.M. method calculates the parameters A and Z(t) allows to avoid the use of a system calibration. In fact, differing from other pulse contour methods:

a) the area under the curve A is calculated considering not only the pulsatile component of the systolic phase, but also the continuous one.

b) the impedance Z(t) takes into account both the systolic and the diastolic phase in their pulsatile and continuous components. Pressure waveform is analyzed in a "perturbative" manner, meaning that all the active and/or purely resistive components that contribute to the heartbeat are considered. In this way, we calculate the specific impedance of the subject under osservation, real time and beat-to-beat.

All these calculations would not be possible without a sampling rate of 1000 Hz.

3) What does Z(t) mean and why it is so difficult to calculate it?

Z(t) represents the cardiovascular impedance; it comprehends heart contractility, arterial compliance, arterial impedance and peripheral vessel resistance. Graphically, Z(t) is expressed by an arterial curve profile. As too many factors simultaneously and continuously concur in determining Z(t), for years nobody found how to measure it.

The attempts to quantify Z(t) led to a determination of a Zfix: the only way to give Z a quantification was to "freeze" it and to consider it stable during time. This was done by PCM based devices via an external calibration (thermo or indicator dilution) or by in vivo/in vitro measurement of impedance.

4) What does CCE is descriptive of and what does it mean?

CCE stays for Cardiac Cycle Efficiency; it is a "stress index", describing the cardiac haemodynamic performance in terms of hemodynamic work performed and energetic expenditure. CCE indicates the efforts committed by the heart to maintain homeostasis. Different energetic expenditures can be spent by the heart to keep the cardiovascular system in some kind of balance; CCE physically represents the ratio between the shape of the pressure wave that patients should ideally have and the actually detected one. Expressed as a pure number, it ranges between +1 and -1. The more positive is CCE, the more is the heart efficiency.

5) Does CCE have any clinical evidence?

Yes! CCE has been compared with LV ejection fraction (EF%) by echocardiography before and after cardiopulmonary bypass [2]. Overall, the correlation coefficient between LVEF% and CCE values was 0.82 (r2 =0.91, p<0.001), and the correlation coefficients at each time of the study ranged from 0.80 to 0.84, p<0.0015. Thus, PRAM seemed a reliable tool for detecting changes in cardiac cycle performance and for monitoring myocardial function and recovery during cardiac surgery. An inverse correlation has also been found between CCE and pro-BNP values [3]. Pro-BNP has been shown to correlate with myocardial hypertrophy (MH) and dysfunction [4].

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[1]Frank O. Die Grundform des arteriellen Pulses. Z Biol. 1899; 37:483-526

[2] Scolletta S, Romano SM, Maglioni E, et al. Left ventricular performance by PRAM during cardiac surgery. Intensive Care Med 2005; 31(Suppl 1):S157

[3] Sabino Scolletta, Federico Franchi, Pierpaolo Giomarelli, Bonizella Biagioli. Asswssment of cardiac surgery patients: the coupling between pro-B-Type natriuretic peptide and arterial wave form analysis“. Cardiomyopathies: Causes, Effects and Treatment, Editors: Peter H. Bruno and Matthew T. Giordano – Nova Publishers – IN PRESS

[4] Ikeda T. Pro-BNP and ANP elevate in proportion to left ventricular end-systolic wall stress in patients with aortic stenosis. Am Heart J 97