American journal of respiratory and critical care medicine
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Am. J. Respir. Crit. Care Med. · Apr 1995
Inspiratory muscle weakness in chronic heart failure: role of nutrition and electrolyte status and systemic myopathy.
Inspiratory muscle weakness has been demonstrated in ambulatory, stable chronic heart failure (CHF) and may contribute to dyspnea during daily living. However, the mechanisms underlying this weakness are unknown. Malnutrition and electrolyte depletion are recognized complications of CHF that may impair skeletal muscle function, and limb muscle weakness and myopathic changes have also been demonstrated in CHF. ⋯ As compared with the matched controls, the CHF patients had reduced inspiratory muscle strength (p < 0.0025), but their expiratory and limb muscle strength were not significantly reduced. CHF patients were not malnourished; they were heavier than matched controls because of increased body fat (p < 0.05). Serum sodium was significantly lower in the CHF patients than in the controls (p < 0.01), but was within the normal range in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)
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Am. J. Respir. Crit. Care Med. · Apr 1995
Interfacing between spontaneous breathing and mechanical ventilation affects ventilation-perfusion distributions in experimental bronchoconstriction.
The effect of interfacing between spontaneous and mechanical ventilation on ventilation-perfusion (VA/Q) distributions was determined during pressure-support ventilation (PSV) and in the presence and absence of spontaneous breathing during biphasic positive airway pressure (BIPAP) in 10 pigs with methacholine-induced bronchoconstriction. Whereas BIPAP without spontaneous breathing provides full and PSV breath-to-breath synchronized ventilatory support, BIPAP allows unrestricted spontaneous breathing throughout the mechanical cycle. Compared with BIPAP with and without spontaneous breathing, PSV effected an increase in ventilatory rate (p < 0.05) and a higher minute ventilation (VE) (p < 0.05). ⋯ Dead space ventilation decreased with spontaneous breathing during BIPAP by 12% compared with PSV (p < 0.05). Dispersion of ventilation distribution was lowest during BIPAP. Uncoupling of spontaneous and mechanical ventilation during BIPAP improved gas exchange by allowing better VA/Q matching during experimental bronchoconstriction.(ABSTRACT TRUNCATED AT 250 WORDS)
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Am. J. Respir. Crit. Care Med. · Mar 1995
Tissue factor pathway inhibitor and von Willebrand factor antigen levels in adult respiratory distress syndrome and in a primate model of sepsis.
Tissue factor pathway inhibitor (TFPI) is an anticoagulant protein primarily synthesized by the endothelium. A major fraction (approximately 85%) of TFPI remains associated with the endothelium, whereas a small fraction (approximately 15%) is secreted into the blood. In our attempts to search for a marker(s) of endothelial injury in the setting of adult respiratory distress syndrome (ARDS), we retrospectively measured plasma TFPI levels in patients at risk for and with ARDS caused by several etiologic factors. ⋯ The vWF-Ag levels were elevated approximately 5-fold after infusion of LD100 concentrations of E. coli at 6 h and 4-fold after infusion of sublethal concentrations of E. coli at 24 h. Autopsies on animals in the LD100 group revealed pulmonary congestion, leukocyte infiltration, edema, and hemorrhage, all suggestive of acute lung injury. Thus, in the setting of acute lung injury plasma vWF-Ag appears to be considerably increased prior to significant damage to the endothelium, whereas increased plasma TFPI occurs only after severe injury.(ABSTRACT TRUNCATED AT 400 WORDS)
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Am. J. Respir. Crit. Care Med. · Mar 1995
Comparative StudyDistribution of regional density and vascular permeability in the adult respiratory distress syndrome.
Although recent X-ray computed tomography (CT) data show that ventral-dorsal gradients in density are common in the adult respiratory distress syndrome (ARDS), we hypothesized that the ventral-dorsal gradient of pulmonary vascular permeability would be evenly distributed in patients with ARDS. We tested this hypothesis by analyzing previously reported data (Am Rev Respir Dis 1991; 143:150-154) obtained by the nuclear medicine imaging technique of positron emission tomography (PET). Measurements of regional lung density (LD), extravascular density (EVD), and the pulmonary transcapillary escape rate (PTCER; an index of vascular permeability) were obtained in eight patients with ARDS and in 10 normal subjects. ⋯ A significantly negative slope of PTCER versus bin was detected in five cases and a positive slope in 3, so that the group value was not significant. These data confirm that ventral-dorsal gradients in LD and EVD exist in patients with ARDS. In contrast, no consistent ventral-dorsal distribution of increased pulmonary vascular permeability is present.