Current opinion in critical care
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Curr Opin Crit Care · Apr 2002
ReviewAdvanced monitoring in the neurology intensive care unit: microdialysis.
Cerebral microdialysis is a relatively new technique for measuring the levels of brain extracellular chemicals, which to date has predominantly been used as a research tool. This review considers the technical aspects of microdialysis, the importance of the commonly measured chemicals, and the use of microdialysis to monitor patients with ischemic stroke, head injury, and subarachnoid hemorrhage. The advantages and disadvantages of microdialysis are discussed, as is its future potential.
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Curr Opin Crit Care · Apr 2002
ReviewLung injury in acute pancreatitis: mechanisms, prevention, and therapy.
Lung injury is the most pertinent manifestation of extra-abdominal organ dysfunction in pancreatitis. The propensity of this retroperitoneal inflammatory condition to engender a diffuse and life-threatening lung injury is significant. ⋯ The variability in the clinical course of pancreatitis renders it a vexing entity and makes demonstration of the efficacy of any specific intervention difficult. The distinct pathologic entity of pancreatitis-associated lung injury is reviewed with a focus on etiology and potential therapeutic maneuvers.
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On the basis of currently available data, it can be suggested that maintained spontaneous breathing during mechanical ventilation should not be suppressed even in patients with severe pulmonary dysfunction if no contraindications, such as increased intracranial pressure, are present. Improvements in pulmonary gas exchange, systemic blood flow, and oxygen supply to tissues, which have been observed when spontaneous breathing was allowed during ventilatory support, are reflected in the clinical improvement in the patient's condition, as indicated by significantly fewer days with ventilation, earlier extubation, and shorter stays in the intensive care unit. ⋯ If ventilatory modalities are limited to those whose positive effects have been documented, then partial ventilatory support can be used as a primary modality even in patients with severe pulmonary dysfunction. Whereas controlled mechanical ventilation followed by weaning with partial ventilatory support modalities has been the earlier standard in ventilation therapy, this approach should be reconsidered in view of the available data.
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The clinical relevance of experimental ventilator-induced lung injury has recently received a resounding illustration by the Acute Respiratory Distress Syndrome Network trial that showed a 22% reduction of mortality in patients with acute respiratory disease syndrome when lung mechanical stress was lessened by tidal volume reduction during mechanical ventilation. This clinical confirmation of the concept of ventilator-induced lung injury has also undisputedly substantiated the experimental observation that excessive tidal volume and/or end-inspiratory lung volume is the main determinant of ventilator-induced lung injury. More recently, attention has focused on the roles and implication in the pathogenesis of ventilator-induced lung injury of inflammatory cells and mediators that may be activated and released either in the alveolar space or in the systemic circulation because of the rupture of the alveolar-capillary barrier and on the cellular response to mechanical stress.
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Curr Opin Crit Care · Feb 2002
ReviewReduced tidal volumes and lung protective ventilatory strategies: where do we go from here?
Three major determinants of lung injury associated with mechanical ventilation have been clearly identified: high pressure/high volume, the shear forces caused by intratidal collapse and decollapse leading to barotrauma/volotrauma/biotrauma. The lung protective strategy aims to reduce the impact of all three determinants. A groundbreaking study showed that reduced tidal volume is less dangerous than high tidal volume, but the researchers did not apply "full" lung protective strategy and did not take into account the shear forces. "Full" protective lung strategy was tested in only one study and in a limited number of patients. Several physiologic studies strongly suggest the advantages of the lung protective strategy.