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Bedside assessment of myocardial performance in the critically ill
J N Shephard1, S J Brecker, T W Evans
1Department of Anaesthesia and Intensive Care, Royal Brompton National Heart and Lung Hospital, London, UK.
Insights
No ideal method exists for monitoring myocardial performance in the ICU. While various techniques offer insights, their routine clinical utility and interpretation for critically ill patients remain unproven, with pulmonary artery catheters likely dominating future monitoring.
Area of Science:
- Critical Care Medicine
- Cardiology
- Physiology
Background:
- Current intensive care unit (ICU) monitoring methods for myocardial performance lack ideal characteristics.
- Interdependence of myocardial performance indices complicates quantification of individual component contributions to overall cardiac function.
- Established diagnostic roles exist for some techniques, but routine clinical utility in influencing practice is often unproven.
Purpose of the Study:
- To review and evaluate current bedside monitoring techniques for myocardial performance in critically ill patients.
- To assess the limitations and potential clinical utility of various monitoring modalities.
- To determine the likely future role of existing and developing technologies in ICU cardiac monitoring.
Main Methods:
- Review of existing literature and clinical practices concerning myocardial performance monitoring in the ICU.
- Comparison of major monitoring techniques including echocardiography, radionuclide imaging, Doppler, and pulmonary artery catheterization.
- Discussion of the practical considerations, limitations, and data interpretation challenges associated with each method.
Main Results:
- Bedside measurements of left ventricular (LV) function are available but their routine use is not established.
- Transesophageal echocardiography and radionuclide techniques have diagnostic roles but practical limitations hinder routine ICU use.
- Doppler techniques offer continuous, non-invasive data but have significant limitations; pulmonary artery catheters remain a mainstay despite ongoing controversies.
Conclusions:
- No single monitoring technique for myocardial performance is currently ideal for the ICU.
- The clinical utility of many individual monitoring indices remains unproven due to interdependence and interpretation challenges.
- Pulmonary artery catheterization, especially with enhanced capabilities like continuous cardiac output monitoring, is expected to remain central to bedside myocardial performance assessment in the critically ill.
Abstract:
No measurement of myocardial performance currently available in the ICU can be regarded is ideal. Table 2 summarises the main features of the major monitoring techniques. As many of the indices of myocardial performance are interdependent, quantifying the contribution of each component to overall cardiac function is not possible currently, and the clinical utility of monitoring each individually is not therefore established. Bedside measurements of LV dimensions, volumes and ejection fraction, and the other indices of systolic and diastolic function can now be made, but the case for their routine use in influencing clinical practice remains unproven. Transoesophageal echocardiography has an important and established diagnostic role and has been used successfully for continuous monitoring during surgery, but practical considerations seriously limit its potential for routine use. Radionuclide techniques allow the measurement of many of the same parameters and have the potential for continuous use, but practical problems and the additional risk of radiation exposure may limit this application in the critical care environment. Doppler techniques are non-invasive, provide continuous data and are simple to operate, but the data provided has important limitations. Although the pulmonary artery catheter has been in use for over twenty years, questions regarding the information is provides concerning myocardial function remain and the extent to which it should influence therapeutic decisions is still controversial. However with the development of additional facilities, particularly the continuous measurement of cardiac output the pulmonary artery catheter seems likely to remain the mainstay of bedside monitoring of myocardial performance in the critically ill in the immediate future.