Articles: respiratory-distress-syndrome.
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We assessed pulmonary mechanics in 35 premature infants with respiratory distress syndrome just before and one hour after the administration of 90 mg of surfactant to each infant. Transpulmonary pressure was measured between the airway opening and an esophageal balloon with use of a differential transducer, and flow rates were measured by a pneumotachometer. Values for pulmonary mechanics were then calculated by microcomputer processing. ⋯ However, in the 25 infants examined during spontaneous breathing with continuous positive airway pressures (identical airway pressures before and after treatment), large and consistent improvements in pulmonary mechanics were found after the administration of surfactant. Tidal volume increased by 32 percent (P less than 0.03), minute ventilation by 38 percent (P less than 0.02), dynamic compliance by 29 percent (P less than 0.004), and inspiratory flow rates by 54 percent (P less than 0.01). We conclude that significant improvement in pulmonary mechanics results from surfactant-replacement therapy for respiratory distress syndrome, but that these mechanical changes are apparent only during spontaneous respiration and can be masked if measurements are made during mechanical ventilation.
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Comparative Study
Activation of the contact system of plasma proteolysis in the adult respiratory distress syndrome.
Adult respiratory distress syndrome (ARDS) is a complex pulmonary clinicopathologic condition associated with pulmonary endothelial injury and blood coagulation activation. In patients with ARDS from all causes, factor VII levels were significantly reduced. Patients with ARDS caused by sepsis had more evidence of intravascular coagulation and fibrinolysis than did patients with trauma-related ARDS by having significantly (p less than or equal to 0.05) increased prothrombin times, activated partial thromboplastin times, and fibrin degradation products, and decreased antithrombin III concentration. ⋯ These findings showed that the proteins of the contact system were more extensively activated in ARDS than were the proteins that contribute to later reactions in intravascular coagulation and fibrinolysis. Activation of the contact system proteins could be the result of endothelial injury occurring as part of ARDS. Intravascular coagulation and fibrinolysis in patients with ARDS also arise from components independent from contact system activation.
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Fourteen consecutive ARDS patients were examined within 24 h from the onset of mechanical ventilation to determine respiratory resistance (Rrs) and compliance (Cstrs), and to assess the influence of "intrinsic" positive end-expiratory pressure (PEEPi) on the measurement of Cstrs. Flow, pressure, and changes in lung volume were measured with the transducers of the Servo 900C Siemens ventilator. Airway occlusion was performed with the end-inspiratory and end-expiratory buttons of the ventilator. ⋯ Maximum and minimum respiratory resistance (Rrsmax and Rrsmin), and frequency-dependence of Rrs were also measured. On average, there was a marked frequency-dependence of resistance, as manifested by the difference between Rrsmax and Rrsmin, with an increase of both Rrsmin (7.7 +/- 4.2 cm H2O.l-1.s) and Rrsmax (14.3 +/- 5.0 cm H2O.l-1.s). The added resistance of the endotracheal tubes and ventilator tubings was flow dependent, and averaged 13.2 +/- 2.9 cm H2O.l-1.s.(ABSTRACT TRUNCATED AT 250 WORDS)
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Seminars in perinatology · Jul 1988
ReviewBiophysical behavior of lung surfactant: implications for respiratory physiology and pathophysiology.
The major emphasis of this article has been the complex, multicomponent system of surfactants that are required for proper pulmonary mechanics and function in the mammalian lung. Although LS was discovered over 30 years ago, and soon after was linked directly with neonatal RDS, it has taken a significant time for researchers to develop a fundamental understanding of the pulmonary surfactant system, and its actions and roles in respiratory physiology. Nonetheless, knowledge about LS has increased greatly over the past decade, and it is now clear that exogenous surfactant replacement therapy for infants with RDS provides a substantial clinical advantage for these patients. ⋯ In dealing with ARDS, it is well to remember that there are a variety of complicating factors, since lung injuries vary with animal age and species, and according to the level and duration of exposure. For example, in the hyperoxic injury described in the previous section there was clearly significant LS involvement. However, had animals been subjected to a lower level of oxygen (eg, 60%), even for a comparatively long time (eg, 21 days), the entire pathologic pattern would have been altered, as demonstrated, for example, by Holm et al.(ABSTRACT TRUNCATED AT 400 WORDS)