Critical care medicine
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Critical care medicine · Mar 1994
ReviewComponents of the work of breathing and implications for monitoring ventilator-dependent patients.
a) To discuss the components of the work of breathing using an established physiologic model (Campbell diagram); b) to describe the requirements of a monitor to measure work; and c) to discuss the implications and relevance for assessing the work of breathing of ventilator-dependent patients. ⋯ Accurate measurement of physiologic and imposed work performed by the patient are essential to assess the afterload on the respiratory muscles, diagnose specific work of breathing abnormalities, and monitor the effects of interventions to mitigate respiratory muscle loading. Work of breathing data are useful in formulating objective guidelines for setting the ventilator appropriately to optimize respiratory muscle loads, e.g., selecting an appropriate amount of pressure support ventilation to decrease the work of breathing to a specific level.
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Critical care medicine · Mar 1994
Optimal release time during airway pressure release ventilation in neonatal sheep.
To systematically investigate the effect of altering release time during airway pressure release ventilation in a neonatal animal model before and after oleic acid-induced acute lung injury. ⋯ In this neonatal laboratory model, release times that were much shorter than previously reported maintained clinically acceptable oxygenation and ventilation. The optimal duration of the release time is a function of the time constant of the respiratory system. During airway pressure release ventilation, alveolar ventilation was maintained without apparent lung volume loss with release times of between 4 tau and 10 tau.
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Critical care medicine · Mar 1994
Hematocrit modifies the circulatory control of systemic and myocardial oxygen utilization in septic sheep.
To describe the relationship between hematocrit and oxygen utilization before and after the onset of a hyperdynamic septic state. ⋯ The normal circulatory compensation to anemia in hyperdynamic sepsis includes increases in cardiac index and whole-body oxygen extraction, although greater reliance is likely placed on the use of systemic flow reserve to maintain tissue oxygen uptake in septic vs. healthy study conditions. Furthermore, increased reliance on myocardial oxygen extraction in sepsis suggests that the normal flow-reserve supporting myocardial oxygen availability may be limited in this syndrome.
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Critical care medicine · Mar 1994
Continuous infusion of haloperidol controls agitation in critically ill patients.
To evaluate the safety and efficacy of continuous infusion of haloperidol in treating agitated critically ill adult patients. ⋯ Continuous infusion of haloperidol effectively controls severe agitation in critically ill patients, reduces requirements for bolus administration of sedatives and nursing time lost to that task, and may facilitate ventilator weaning. Parenteral administration of haloperidol was associated with few complications in > 1,340 patient-hours of continuous administration.
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Critical care medicine · Mar 1994
Nitric oxide synthase inhibition with NG-mono-methyl-L-arginine reversibly decreases cerebral blood flow in piglets.
We tested the hypothesis that, in piglets, the intravenous administration of the reversible inhibitor of nitric oxide synthase, NG-mono-methyl-L-arginine, decreases cerebral blood flow via a mechanism unrelated to cerebral oxygen consumption. ⋯ These data suggest that nitric oxide and/or a nitric oxide-containing substance is an important mediator of cerebrovascular tone in piglets, acting via a mechanism unrelated to altering cerebral oxygen consumption.