American journal of respiratory and critical care medicine
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Am. J. Respir. Crit. Care Med. · Jan 1998
Leukocyte activation and flow behavior in rat skeletal muscle in sepsis.
In animal models of endotoxemia, sepsis is associated with the accumulation of leukocytes and altered microvascular perfusion. In order to test the hypothesis that bacterial sepsis upregulates leukocyte-endothelial adhesion, we used intravital microscopy to examine the flow behavior of leukocytes in the postcapillary venules (PCV) of rats made septic by cecal ligation and perforation (CLP). Animals were randomized to CLP or sham study groups and studied 6 h, 24 h, or 48 h later. ⋯ After correction for the reduction in systemic leukocyte count associated with CLP, the effect of sepsis on leukocyte adhesion and extravasation no longer reached statistical significance. These findings suggest that chronic (6 to 48 h) bacterial sepsis does not upregulate leukocyte adhesion in a manner similar to that seen in models of acute endotoxemia. These data suggest that the increased microcirculatory flow heterogeneity seen in this and other models of bacterial sepsis may not be explained by leukocyte entrapment in postcapillary venules.
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Am. J. Respir. Crit. Care Med. · Dec 1997
Effects of noninvasive ventilation on pulmonary gas exchange and hemodynamics during acute hypercapnic exacerbations of chronic obstructive pulmonary disease.
Noninvasive positive pressure ventilation (NIPPV) can replace tracheal intubation in acute exacerbations of chronic obstructive pulmonary disease (COPD) with severe hypercapnic respiratory failure. However, the underlying mechanisms by which NIPPV improves pulmonary gas exchange are not known. We studied 10 male COPD patients (68 +/- 8 [SD] yr) with acute severe hypercapnic respiratory failure within 36 h after hospital admission. ⋯ We conclude that improvement in respiratory blood gases during NIPPV is essentially due to higher alveolar ventilation (p < 0.001) and not to improvement in VA/Q relationships. The increase in AaPO2 was explained by the rise in R due to an increased clearance of body stores of C02 during NIPPV. Our results indicate that attainment of an efficient breathing pattern rather than high inspiratory pressures should be the primary goal to improve arterial blood gases during NlPPV in this type of patient.
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Am. J. Respir. Crit. Care Med. · Dec 1997
Implementation of bronchoscopic techniques in the diagnosis of ventilator-associated pneumonia to reduce antibiotic use.
In intensive care units, a large proportion of antibiotics are prescribed for presumed episodes of ventilator-associated pneumonia (VAP). VAP is usually diagnosed on a combination of clinical, radiographic, and microbiologic criteria with a high sensitivity but low specificity for VAP. As a result, patients may receive antibiotics unnecessarily. ⋯ Withholding of antibiotic therapy had no negative effect on the recurrence of a clinical suspicion of VAP or on mortality rates. We conclude that addition of bronchoscopic techniques to the criteria for VAP may help to reduce antibiotic use. However, the definite benefits and cost-effectiveness of these techniques should be analyzed in a randomized study.
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Am. J. Respir. Crit. Care Med. · Dec 1997
Influence of ethnicity and gender on airway function in preterm infants.
While maximal expiratory flow at functional residual capacity, calculated from partial expiratory flow volume curves (V'maxFRC), is a valuable measure of peripheral airway function in infants, limited data are available in preterm infants despite their high prevalence of respiratory problems. To investigate the influence of gender and ethnic group, V'maxFRC and other indices of respiratory function were measured in 28 black and 28 white preterm infants (50% female in each group) at time of discharge from the neonatal unit (mean [SD] weight 2.36 [0.3] kg, postnatal age 19 [9] d). No infant had any history of cardiorespiratory disease and all were born to non-smoking mothers. ⋯ L-1.s). Similarly, time to peak tidal expiratory flow as a proportion of total expiratory time (tPTEF:tE) was significantly longer in black than white (95% CI: 0.06, 0.20) and in female than male (95% CI: 0.02, 0.15) infants. These findings suggest that certain parameters of airway function may be influenced by both ethnic group and gender in preterm infants, both of which should therefore be taken mw account when investigating the effects of disease and/or therapeutic interventions in this group.