Current opinion in critical care
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Curr Opin Crit Care · Jun 2005
ReviewHow does interruption of cardiopulmonary resuscitation affect survival from cardiac arrest?
Survival rates from cardiac arrest are unacceptably low. The present review aims to summarize recent contributions to cardiopulmonary resuscitation research in relation to hemodynamic consequences and especially survival resulting from interruption of chest compressions for defibrillation and rescue breathing. ⋯ Interruption of cardiopulmonary resuscitation negatively affects survival from cardiac arrest. Fewer interruptions for interventions and interventions that take less time may improve survival.
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Because the right side of the heart supplies blood to the pulmonary circulation, its integrity is required for both adequate respiratory and circulatory function. By reducing pulmonary perfusion, right-sided heart failure may compromise arterial oxygenation and left ventricular filling, and monitoring of right-sided heart function at the bedside in critically ill patients is fundamental. Two recent clinical commentaries have focused on the invaluable help provided by echocardiography for this purpose. ⋯ Monitoring of right-sided heart function is essential in a clinical setting associated with hemodynamic instability, such as severe sepsis or acute coronary artery obstruction, and also in that it is associated with increased pulmonary vascular resistance, as in massive pulmonary embolism or acute respiratory failure. Moreover, use of mechanical ventilation requires regular evaluation of its effects on the right side of the heart.
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Curr Opin Crit Care · Jun 2005
ReviewWaveform analysis of ventricular fibrillation to predict defibrillation.
Ventricular fibrillation occurs during many cases of cardiac arrest and is treated with rescue shocks. Coarse ventricular fibrillation occurs earlier after the onset of cardiac arrest and is more likely to be converted to an organized rhythm with pulses by rescue shocks. Less organized or fine ventricular fibrillation occurs later, has less power concentrated within narrow frequency bands and lower amplitude, and is less likely to be converted to an organized rhythm by rescue shocks. Quantitative analysis of the ventricular fibrillation waveform may distinguish coarse ventricular fibrillation from fine ventricular fibrillation, allowing more appropriate delivery of rescue shocks. ⋯ Many quantitative ventricular fibrillation measures could be implemented in current generations of monitors/defibrillators to assist the timing of rescue shocks during clinical care. Emerging data suggest that a period of chest compressions or reperfusion can increase the likelihood of successful defibrillation. Therefore, waveform-based prediction of defibrillation success could reduce the delivery of failed rescue shocks.
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Curr Opin Crit Care · Jun 2005
ReviewHemodynamic assessment of critically ill patients using echocardiography Doppler.
The evaluation of hemodynamic status in critically ill patients is a leading recommended indication of transesophageal echocardiography in the intensive care unit. Advantages and diagnostic yield of transesophageal echocardiography in this setting are particularly relevant when considering limitations and questioned prognostic impact of pulmonary artery catheterization. ⋯ Transesophageal echocardiography appears well suited for the determination of cardiac index and to track its variations after therapeutic interventions. Although repeated measurements of left ventricular end-diastolic dimension allows to accurately track preload variations, a single determination is not reliable to predict fluid responsiveness in intensive care unit patients. Identification of preload dependence in hemodynamically unstable patients currently tends to rely mainly on dynamic parameters that use cardiopulmonary interactions under mechanical ventilation. Transesophageal echocardiography also allows to adequately assess right ventricular function and left ventricular filling pressure using combined Doppler modalities. Adequate education and training of intensivists and anesthesiologists is crucial to further develop the use of transesophageal echocardiography in the intensive care unit setting. Despite the absence of randomized controlled studies documenting transesophageal echocardiography benefits on patient outcome, present evidence and experience strongly recommend a larger use of echocardiography Doppler for a comprehensive functional hemodynamic assessment of critically ill patients with circulatory failure.
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To summarize the relevant peer-reviewed publications over the past year that addressed issues of when to give (or not give) fluid to the critically ill patient. ⋯ Preload is not preload responsiveness. Functional measures of preload responsiveness exist and are superior to traditional measures of filling pressures in driving resuscitation in critically ill patients.