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Reevaluation of the role of cellular hypoxia and bioenergetic failure in sepsis

Article Abstract:

A lack of oxygen at the cellular level (cellular hypoxia) or failure of the energy-producing mechanism of the cell may not necessarily cause multi-organ failure in sepsis. Sepsis is an infection in the blood and tissues that is a major cause of death in intensive care units. Animal studies using NMR spectroscopy to evaluate energy production in cells during sepsis show that there is no defect in energy production compared to control, or healthy, animals. Studies using chemicals whose binding to cells indicates the level of oxygen in the cell show no evidence of cellular hypoxia in muscle, heart, lung and brain tissue in septic rats. Many patients with sepsis have elevated blood levels of lactate, which doctors assumed was an indication of cellular hypoxia. But there are other metabolic factors that could cause elevated lactate, and many patients' lactate levels do not drop when they are treated with oxygen or replacement fluids.

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Abnormal cellular metabolism in sepsis: a new interpretation

Article Abstract:

A report in this issue of JAMA indicates that the high blood lactate levels seen in patients with sepsis, a serious infection of the blood and tissues, may not be a result of cellular hypoxia. Cellular hypoxia is a decrease in the oxygen supply to cells. Since lactate production is associated with anaerobic metabolism, doctors assumed that septic patients had cellular hypoxia. But patients who are volume-depleted may exhibit signs of cellular hypoxia simply because of inadequate perfusion of organs. Other researchers have found increased uptake and metabolism of glucose in cells subjected to stress, which could account for increased lactate production in the presence of adequate oxygen. If these animal studies can be reproduced in humans, then it may not be necessary to give septic patients oxygen. These studies still do not explain the multiple organ failure that can occur in septic patients.

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A new therapy for the adult respiratory distress syndrome

Article Abstract:

Inhaled nitric oxide may be useful in the treatment of adult respiratory distress syndrome (ARDS). ARDS can result from direct injury to the lungs, such as pneumonia, a drug reaction or a systemic disorder. It is characterized by inadequate oxygenation, increased pulmonary-artery pressure, pulmonary edema and multi-organ dysfunction, and about 60% of ARDS cases are fatal. Treatment for ARDS is complicated because therapeutic attempts to decrease pulmonary-artery pressure tend to lower overall blood pressure and injure lung tissue, exacerbating the oxygen insufficiency. Recently, 10 patients with ARDS inhaled nitric oxide. Pulmonary-artery pressure dropped in all patients, but systemic pressure was not affected. Furthermore, among nine of the patients who were treated with both nitric oxide and prostacyclin, oxygenation improved with nitric oxide treatment but worsened with prostacyclin.

Health aspects, Care and treatment, Nitric oxide, Acute respiratory distress syndrome, Adult respiratory distress syndrome

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