Critical care medicine
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Management of shock is generally guided by hemodynamic data, but the true aim of therapy should be optimizing oxygen delivery (DO2) and consumption (VO2). Available data do not support the hypothesis that there is a single critical threshold of DO2 below which tissue hypoxia occurs; thus, DO2 and VO2 should be addressed for each patient. Interventions that raise BP, such as infused catecholamines, may actually decrease DO2, as can mechanical ventilation with PEEP. Therefore, the clinician should avoid responding solely to hemodynamic data and should direct interventions toward delivering the optimum amount of oxygen to the patient's tissues.
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Critical care medicine · Jan 1990
ReviewTherapy of shock based on pathophysiology, monitoring, and outcome prediction.
High-risk patients who survived general (noncardiac) surgery were observed to have cardiac index (CI) values averaging 4.5 L/min.m2, oxygen delivery (DO2) greater than 600 ml/min.m2, and oxygen consumption (VO2) 170 ml/min.m2 during the first 2 or three days postoperatively. Patients who subsequently died maintained relatively normal CI, DO2, and VO2 values in this period. Values of other variables in survivors and nonsurvivors were not appreciably different. ⋯ Optimal goals were more easily attained with colloids, red cells, and an inotropic agent, dobutamine. Dobutamine was used because, in a prospective crossover clinical trial with dopamine at various doses, dobutamine produced greater increases in flow and flow-related variables. More importantly, it improved tissue perfusion as reflected by greater increases in VO2 and greater reductions in pulmonary and systemic vascular resistance.
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Critical care medicine · Jan 1990
Comparative StudyAutomated sulfur hexafluoride washout functional residual capacity measurement system for any mode of mechanical ventilation as well as spontaneous respiration.
A new sulfur hexafluoride (SF6) washout functional residual capacity (FRC) measurement system has been developed which will work with any mode of mechanical ventilation, as well as with spontaneous respiration. This system was evaluated in three different human studies. In the first two studies, the accuracy of the system was compared with He dilution and body plethysmography in 12 spontaneously breathing normal volunteers and in 12 spontaneously breathing chronic obstructive pulmonary disease (COPD) patients. ⋯ The "stable" periods were 14 +/- 2 h long and ranged from 60 min to 63.5 h. The reproducibility for all 12 patients was 188 +/- 17 ml or 11.7 +/- 0.7%. This automated SF6 washout system should make routine FRC measurements in patients who are being mechanically ventilated simple and easy to do.(ABSTRACT TRUNCATED AT 250 WORDS)
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Critical care medicine · Jan 1990
ReviewHeart failure in septic shock: effects of inotropic support.
Many animal studies have attempted to simulate the circulatory responses to Gram-negative septicemia (iv infusion of live bacteria, fecal inoculation into body cavities, and administration of purified endotoxins by various routes), but the contribution of the heart to the adverse hemodynamic derangements and thus to the pathogenesis of shock is difficult to determine because of peripheral vascular events that influence cardiac performance. When blood pools in the periphery, venous return decreases and cardiac output can decrease without a primary myocardial defect being present. However, early heart dysfunction has been recognized in sepsis. Hemodynamic monitoring has not reduced overall mortality, but it has been helpful in guiding fluid administration and evaluating response to vasopressor therapy.
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Critical care medicine · Jan 1990
Correct positioning of an endotracheal tube using a flexible lighted stylet.
Endotracheal intubation is not without complications, among the most serious of these being misplacement of the endotracheal (ET) tube. Unrecognized esophageal placement is a lethal complication, but even when placed in the trachea, ET tubes can be displaced distally and enter a mainstem bronchus. Correct positioning of an ET tube is usually defined as the placement of the tube within the trachea approximately 5 cm above the carina. ⋯ A chest x-ray was taken and the distance of the tube tip from the carina was calculated. In each case the tube tip could be placed consistently at a level 5 +/- 1 cm from the carina by observing the maximal transilluminated glow at the sternal notch. We conclude that transillumination of the neck using a flexible lighted stylet can accurately and consistently position an ET tube at an appropriate distance above the carina.(ABSTRACT TRUNCATED AT 250 WORDS)