Technology is now available to allow a complete haemodynamic analysis; however this is only used in a small proportion of patients and seems to occur when the medical staff have the time and inclination. As a result of this, significant delays occur between an event, its diagnosis and therefore, any treatment required. We can speculate that we should be able to collect enough real time information to make a complete, real time, haemodynamic diagnosis in all critically ill patients. This article advocates for “intelligent haemodynamic monitoring”. Following the steps of a functional analysis, we answered six basic questions. (1) What is the actual best theoretical model for describing haemodynamic disorders? (2) What are the needed and necessary input/output data for describing this model? (3) What are the specific quality criteria and tolerances for collecting each input variable? (4) Based on these criteria, what are the validated available technologies for monitoring each input variable, continuously, real time, and if possible non-invasively? (5) How can we integrate all the needed reliably monitored input variables into the same system for continuously describing the global haemodynamic model? (6) Is it possible to implement this global model into intelligent programs that are able to differentiate clinically relevant changes as opposed to artificial changes and to display intelligent messages and/or diagnoses? 1. Introduction Thirty years ago, tracking the heart rate (HR) was the only means of automatic, continuous, real-time and noninvasive, hemodynamic monitoring. A more elaborate level of monitoring was necessarily invasive and required a central venous catheter for continuous pressure (CVP) assessment. A third level was based on the placement of a pulmonary artery catheter (PAC) and of an arterial line for continuous pulmonary artery pressure (PAP) and systemic arterial pressure (SAP) curve recording. From this traditional data monitoring, a complete haemodynamic diagnosis was obtained on demand by the measurement of a set of additional variables, such as cardiac output (CO), pulmonary wedge pressure (PWP), blood lactate, haemoglobin concentration (Hb), arterial haemoglobin oxygen saturation (SaO2), and mixed venous haemoglobin oxygen saturation (SvO2). From these elementary data, several other variables were derived such as pulmonary and systemic resistance to flow (PVR and SVR), right and left ventricles stoke work (RVSW and LVSW), and tissue oxygenation indices: oxygen arterial and venous content (CaO2 and CvO2), oxygen delivery (DO2),
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