Critical care clinics
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Current monitoring of critically ill patients uses measurement of global parameters such as oxygen consumption and lactate levels. With development of new monitoring technologies, it may be possible to monitor patients on an organ or tissue level, allowing manipulation of specific organ or tissue perfusion. Potentially useful techniques for monitoring tissue energetics in the future include NIR and NMR spectroscopy. ⋯ Both of these techniques may be useful for identification of dysoxia or oxygen-limited mitochondrial turnover. Experimental evidence suggests that organs in the septic state are more sensitive to dysoxia. Implications for the care of the patient with sepsis include possible decreased tolerance to factors leading to dysoxia, such as hypoxemia, hemodilution, or ischemia.
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Critical care clinics · Oct 1996
ReviewDetermination of oxygen delivery and consumption versus cardiac index and oxygen extraction ratio.
Measuring cardiac output without knowledge of the oxygen extraction by the tissues is of limited value. Instead of calculating oxygen consumption and oxygen delivery, a diagram relating cardiac index to the oxygen extraction ratio is proposed to interpret hemodynamic data at the bedside. This diagram is particularly helpful in interpreting cardiac index in the presence of changes in hemoglobin or oxygen demands and in evaluating the effects of therapy.
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Critical care clinics · Oct 1996
ReviewHemodynamics and positive end-expiratory pressure in critically ill patients.
This article examines the factors that affect the transmission of airway pressures to intrathoracic structures. The effects of positive end-expiratory pressure on central venous pressures, cardiac filling pressures, and right and left ventricular function are discussed. Various techniques for estimating intrathoracic pressures and their limitations are reviewed.
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Arterial blood gas (ABG) measurements are one of the most frequently requested laboratory examinations in critically ill patients. ABGs include measurement of pHa, PaCO2, PaO2, and oxyhemoglobin saturation. These measurements allow for assessment of the nature, progression, and severity of metabolic and respiratory disturbances.
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Critical care clinics · Oct 1996
ReviewThe new pulmonary arterial catheters. Right ventricular ejection fraction and continuous cardiac output.
The flow-directed pulmonary artery catheter is the mainstay of hemodynamic monitoring in critically ill and injured patients. During its 25-year history, the catheter has been modified to measure mixed venous oxygen saturation, right ventricular ejection fraction, and recently, continual thermodilution cardiac output. The clinical application of the new generations of pulmonary artery catheters is reviewed in this article.