MostCare Versus Echo-Doppler for Cardiac Output Measurement

Overview

Recently, an uncalibrated minimally invasive Pulse-code Modulator (PCM) has been developed: the MostCare system. This monitoring system is powered by Pressure Recording Analytical Method (PRAM), which is based on the mathematical analysis of the arterial pressure profile changes. It allows beat-to-beat Stroke Volume (SV) assessment from the pressure signal recorded invasively in radial, brachial, or femoral arteries. The most innovative features of this method are: 1) the lack of a calibration requirement, 2) the analysis of the arterial wave signal is performed at 1000 Hz, 3) a dedicated arterial catheter-transducer is unnecessary. MostCare is powered by PRAM (Pressure Recording Analytical Method) algorithm. The investigators primary end-point was to evaluate the relationship between Cardiac Output (CO) measured by MostCare with CO calculated with Echo-Doppler in Intensive Care Unit (ICU) patients under different clinical conditions. As a secondary end-point the investigators evaluated the relationship between CO measured by MostCare with CO obtained with thermodilution techniques (standard bolus thermodilution or transpulmonary thermodilution, i.e. PiCCO system). This is a prospective multicentre observational study.

(\*) Study design A. MostCare system data acquisition Before each CO measurement, the arterial pressure catheter and transducer quality will be assessed as follows: easy aspiration of 5 ml of blood easily re-injected without resistance; visual assessment of the quality of the arterial waveform contour; adequate response to the flush test (square wave). If necessary, the best position for the signal quality will be checked by extending the wrist and manipulating the catheter. For each determination of Echo-Doppler (and ThD-CO when applicable), a corresponding value for MostCare must be obtained by averaging the individual beats over the same time necessary to obtain the Echo-doppler-CO (and ThD-CO when applicable) measurements. B. Echo-Doppler data acquisition (transoesophageal - TOE - or transthoracic - TTE - echo) Echo-Doppler-CO will be measured using the standard formula CSA x VTI (cross sectional area x velocity time integral x heart rate in ml/min). 2D measurement of the aortic annulus diameter allows calculation of the flow CSA which is then multiplied by the VTI (velocity time integral) of the Pulsed Doppler flow velocity profile across the aortic valve to determine the SV. Other hemodynamic variables as an ancillary part of the study will compare shortening fraction (SF) or EF fraction from Echocardiography with CCE and dp/dt. C. Thermodilution data acquisition (ThD-CO) (when applicable) Data coming from ThD pulmonary artery catheter (PAC) or a CVC + femoral artery catheter (transpulmonary thermodilution, PiCCO system) will be collected from the monitor itself or the system for patient monitoring used in the units. For standard PAC-ThD-CO, five consecutive injections of 10 ml of 5% glucose cold solution will be randomly injected during respiratory cycle over a 5-min period. Thermodilution-CO (or PiCCO-CO) will be calculated as the average of the five measurements. All these 5 measurements will be collected. MostCare, Echo-doppler (and Thermodilution when applicable) Change in ventilator parameters, sedation drugs, or fluid infusions or vasopressor dose will not be allowed during the acquisition time. (\*) Study timing and procedure For each patient CO determinations will be performed as follows: Mandatory measurements: • Baseline: (MostCare + Echo-doppler simultaneously, and MostCare + Echo-doppler + Thermodilution when applicable) = single comparison between techniques. Recorded but not mandatory measurements (fitting to the therapeutic protocol used in each center): • Pre- and post- treatment (fluid challenge, vasoactive drugs and inotropics changes) (MostCare + Echo-doppler simultaneously, and MostCare + Echo-doppler + Thermodilution when applicable) = dynamic comparison between techniques (two measures). This will allow a sub-analysis of CO (the trend of CO) changes, validity of trend, for both SV and CO before and after a therapeutic intervention. Data to be collected: Patient: demographic, anthropometric, pre-medical history, indication(s) for ICU admission; (cardiovascular diseases and cardiac function, respiratory diseases, etc...), severity scores (SAPS II, SOFA, ….). All patients enrolled will be analysed in intention-to-treat even data recording failed. In this case, that would be a limit if any, for the tested technique. Hemodynamic MostCare: SV, HR, CO, CCE, ∆P/∆T, ABPs, ABPd, ABPm. Other hemodynamic data: CVP, PaoP, SvO2, lactate,... Echocardiography: stroke volume, heart rate, cardiac output. Other hemodynamic variables are allowed to be collected by Echo according to the centre protocols and the experience of each centre. Cardiac and vasoactive drugs dose or infusion rate will be collected: dobutamine, dopamine, norepinephrine, epinephrine, nitrates, beta-blockers, ACE-I,ecc. Ventilatory: mechanical ventilation settings: mode of ventilation (CPAP, BiPAP, VC, PC), pressure support (if applicable), peak and plateau pressure, PEEP level, FiO2 oxygenation (SaO2, PaO2,…) ICU stay and outcome: morbidity (number and type of complications), length of stay, mortality. (\*) Statistical analysis and methodology, number of patients to be enrolled, duration of the study: Collected data will be copied on an excel file to be properly independently analyzed with a statistical software. Correlation tests (Spearman or Pearson), Student paired t-test, and Bland-Altman analysis will be applied. A minimum of 30 patients per centre will be enrolled in the study in a period of 18 months. This "minimum number" of patients is mandatory as: 1) the enrollment of 30 patients per centre eliminates the potential bias that may occur when few data come from a single centre, 2) minimum 300 patients enrolled represents a suitable number to obtain the "statistical power" necessary to validate the comparison between the different methods, and 3) further analysis and comparisons in subgroup of patients having similar clinical settings can be performed.