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Journal of Clinical Monitoring and Computing (2008) 22:225255
DOI: 10.1007/s10877-008-9121-4 Springer 2008
SCATA-ESCTAIC 2007: LECTURE ABSTRACTS (Thursday Session I Lecture b)CARDIAC PHYSIOLOGY AND ALGORITHIMS FOR MINIMALLY INVASIVE CARDIAC OUTPUT MEASUREMENT: RELEVANCE TO THE MANAGEMENT OF SEPSISDr. Karen Stuart-Smith, Consultant Anaesthetist Glan Clwyd Hospital, Rhyl, UK
Fluid management in septic shock, and the optimisation of cardiac output in sepsis, have been a matter of intense debate-and changes in management fashion-for 30 years.A major advance in the assessment and treatment of septic patient was considered to be the measurement of cardiac output, and derived indices such as systemic vascular resistance, via the pulmonary artery catheter (PAC).Although use of the PAC has not been shown to improve outcome in septic shock1, cardiac output continues to be considered to be an important index in sepsis management. The perceived problem that the PAC is an invasive monitor with potential complications1 has led several companies to develop minimally invasive cardiac output monitoring. In general these devices depend on analysis of the arterial pulse wave, measured at either the radial or femoral artery-pulse contour analysis. Individual company algorithims arise from modications of Wesselings three-element model of an arterial pressure pulse propagated along a vessel2.
Cardiac output measurement via minimally invasive devices has been shown to correlate well with the PAC, long considered the gold standard. Unfortunately, like thePAC, these devices have not yet been shown to have a benecial impact on the outcome in sepsis3. This is in contrast to the clinical results in early goal directed therapy, where aggressive early uid management may improve the outcome in elective major surgery and acutely ill patients. This talk will consider the following:
1. The PAC was originally designed for use in cardiac patients, and so makes assumptions about the quality of the cardiac muscle and arterial tone which may not be relevant to sepsis. This would explain the lack of effect of the PAC on outcome.
2. Minimally invasive cardiac output monitors are designed to make the same assumptions, and may compound the problem by not sufciently taking into account the greater distensibility of septic vessels and wider recruitment of vascular beds (secondary to nitric oxide production from white cells) that may dampen the pulse pressure signal in endotoxaemia.
3. Early goal...