Current opinion in critical care
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Curr Opin Crit Care · Jun 2002
Review Comparative StudyLithium dilution measurement of cardiac output and arterial pulse waveform analysis: an indicator dilution calibrated beat-by-beat system for continuous estimation of cardiac output.
Lithium dilution cardiac output (LiDCO trade mark; LiDCO, London, UK) is a minimally invasive indicator dilution technique for the measurement of cardiac output. It was primarily developed as a simple calibration for the PulseCO trade mark (LiDCO, London, UK) continuous arterial waveform analysis monitor. The technique is quick and simple, requiring only an arterial line and central or peripheral venous access. ⋯ The nominal stroke volume is converted to actual stroke volume by calibration of the algorithm with LiDCO trade mark. Initial studies indicate good fidelity, and the results from centers in the United States and the United Kingdom are extremely encouraging. The PulseCO trade mark monitor incorporates software for interpretation of the hemodynamic data generated and provides a real-time analysis of arterial pressure variations (ie, stroke volume variation, pulse pressure variation, and systolic pressure variation) as theoretical guides to intravascular and cardiac filling.
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Distributive shock is a common problem in intensive care. Systemic hypotension is a medical emergency and will cause end-organ injury if not reversed. There are relatively few medications available to treat distributive shock. ⋯ Thus, the appropriate therapeutic endpoints for vasopressor therapy are not uniform for all patients. Similarly, the available evidence comparing vasopressor agents in terms of safety and efficacy is limited. When used at doses necessary to reverse distributive shock, less potent vasoconstrictors (eg, dopamine) do not appear to be safer than more potent ones (eg, norepinephrine) and do not appear to be as effective.
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Basic life support and rapid defibrillation for ventricular fibrillation or pulseless ventricular tachycardia are the only two interventions that have been shown unequivocally to improve survival after cardiac arrest. Several drugs are advocated to treat cardiac arrest, but despite very encouraging animal data, no drug has been reliably proven to increase survival to hospital discharge after cardiac arrest. This review focuses on recent experimental and clinical data concerning the use of vasopressin, amiodarone, magnesium, and fibrinolytics during advanced life support (ALS). ⋯ Fibrinolytics are likely to be beneficial when cardiac arrest is associated with plaque rupture and fresh coronary thrombus or massive pulmonary embolism. Fibrinolysis may also improve cerebral microcirculatory perfusion once a spontaneous circulation has been restored. A planned, prospective, randomized trial may help to define the role of fibrinolysis during out-of-hospital CPR.
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Controversy concerning the pulmonary artery catheter (PAC) and its use as a bedside clinical tool continues to be a significant bone of contention. In the pursuit of evidence-based medicine, a substantial effort has been made over the last 25 years to demonstrate the benefit or lack thereof of PAC-led therapy, and this endeavor still persists with large, randomized, clinical trials currently in progress both in the United States and in the United Kingdom. This article reviews the core evidence for and against PAC efficacy and safety and considers the most appropriate method for validation of such a device.
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Cardiac arrest survival rates remain low despite increased access to advanced cardiac life support. Survival from cardiac arrest is, at least in part, related to the perfusion pressures and blood flow achieved during cardiopulmonary resuscitation (CPR). A number of alternative CPR devices have been developed that aim to improve the perfusion pressures and/or blood flow achieved during CPR. ⋯ A number of other devices, including the inspiratory impedance threshold valve, minimally invasive direct cardiac massage, phased chest and abdominal compression-decompression CPR, and vest CPR, are all capable of improving perfusion pressures and/or blood flow compared with standard external chest compressions. However, no convincing human outcome data has been produced yet for any of these devices. Although an interesting area of research, none of the alternative CPR devices convincingly improve long-term patient outcomes.