Critical care medicine
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To provide an overview of the splanchnic hemodynamic response to circulatory shock. ⋯ While angiotensin II has been viewed primarily as the mediator responsible for the increased total vascular resistance seen during (and after) cardiopulmonary bypass, it may also cause the disproportionate decrease in mesenteric perfusion, as measured in human subjects by intraluminal gastric tonometry and galactose clearance by the liver, as well as the consequent development of the multiple organ failure syndrome seen in 1% to 5% of patients after cardiac surgery.
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Critical care medicine · Feb 1993
Descriptive analysis of critical care units in the United States: patient characteristics and intensive care unit utilization.
To gather data about occupancy, admission characteristics, patients' ages, and types of therapy utilized in ICUs in the United States. ⋯ This report should be viewed as the beginning step of an effort to improve both the information base available on critical care medicine and the performance of ICUs. Our survey findings provide an introduction into the everyday workings of critical care units throughout the United States. Research is required to determine which patients will benefit from intensive care and how to efficiently utilize the vast technology we have available for them in a world with limited financial resources, an aging population, and a multiplicity of societal and ethical concerns.
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To remind practitioners of the conventional goals of resuscitation of overt hypotensive or uncompensated shock ("ABC," for airway, breathing, and circulation) and to introduce additional goals, represented by successive letters of the alphabet, to aid clinicians in recognizing the persistence of compensated shock in the splanchnic organs and in achieving more complete resuscitation by eliminating inadequate tissue perfusion in these organs. ⋯ In traumatic and septic shock, multiple system organ failure is associated with a persistent state of compensated shock in which hypotension and oliguria are corrected, but in which inadequate perfusion persists in the splanchnic organs and especially in the mucosal lining of the gut. The additional goals recommended include "D" for increasing the delivery of oxygen to levels that meet the metabolic demand by all tissues in the body, especially those tissues within the splanchnic circulation, and "E" for ensuring extraction and utilization of oxygen by the tissues. Future needs for goals that address reperfusion injury, translocation of bacterial toxins, and the release of toxic mediators are also considered.
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This paper reviews presently available techniques for monitoring the adequacy of tissue oxygenation, emphasizing the practical and theoretical problems that exist with presently used measurements. ⋯ In attempting to develop tools to assess adequate tissue oxygenation, emphasis should be placed on the monitoring of individual tissues that are felt to be highly susceptible to reduced oxygen delivery and key to overall survival. Preliminary data involving measurements of the interstitial pH of the gastrointestinal tract suggest that this measurement may be one approach to pursue.
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Critical care medicine · Feb 1993
Comparative StudyImposed work of breathing and methods of triggering a demand-flow, continuous positive airway pressure system.
To compare the inspiratory imposed work of breathing during spontaneous ventilation with continuous positive airway pressure using three methods of triggering "ON" the demand-flow system of a ventilator: a) conventional pressure triggering with the pressure measuring/triggering site inside the ventilator on the exhalation limb of the breathing circuit; b) tracheal pressure triggering from the tracheal or carinal end of the endotracheal tube; and c) flow-by (flow triggered) triggering. ⋯ An endotracheal tube is a resistor in the breathing apparatus over which a pressure decrease must be developed by the patient in order to inhale spontaneously. An endotracheal tube, therefore, imposes substantial resistance and work. The results indicate that the pressure measuring/triggering site for a ventilator's demand-flow system should be at the tracheal or carinal end of an endotracheal tube so as to effectively decrease the resistance of the endotracheal tube, thus, decreasing the patient's work of breathing.