The American review of respiratory disease
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Am. Rev. Respir. Dis. · May 1988
Effect of almitrine on ventilation-perfusion distribution in adult respiratory distress syndrome.
Almitrine improves ventilation/perfusion relationships (VA/Q) in COPD, but its effects in ARDS, in which VA/Q mismatching is the cause of severe hypoxemia, are not known. The effects of almitrine on pulmonary gas exchange and circulation were assessed in 9 patients with ARDS who were sedated, paralyzed, and mechanically ventilated at constant FlO2 (range, 0.48 to 0.74). Systemic and pulmonary hemodynamics, conventional gas exchange, and the VA/Q distribution by the multiple inert gas elimination technique (MIGT) were measured before (baseline), during (ALM 15), at the end of (ALM 30), and at 30-min intervals after (POSTALM 30, 60, and 90) the intravenous infusion of 0.5 mg/kg body weight of almitrine over 30 min. ⋯ The Ppa increased from 26 +/- 5 to 30 +/- 5 mm Hg without changes in QT. Changes were transient, returning toward baseline 30 min after stopping the infusion of the drug. Almitrine significantly reduced the VA/Q inequalities present in ARDS and may be useful in the management of those patients.
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Am. Rev. Respir. Dis. · May 1988
High inflation pressure pulmonary edema. Respective effects of high airway pressure, high tidal volume, and positive end-expiratory pressure.
The respective roles of high pressure and high tidal volume to promote high airway pressure pulmonary edema are unclear. Positive end-expiratory pressure (PEEP) was shown to reduce lung water content in this type of edema, but its possible effects on cellular lesions were not documented. We compared the consequences of normal tidal volume ventilation in mechanically ventilated rats at a high airway pressure (HiP-LoV) with those of high tidal volume ventilation at a high (HiP-HiV) or low (LoP-HiV) airway pressure and the effects of PEEP (10 cm H2O) on both edema and lung ultrastructure. ⋯ It was markedly reduced by PEEP, which, in addition, preserved the normal ultrastructural aspect of the alveolar epithelium. This was in striking contrast to the diffuse alveolar damage usually encountered in this type of edema. To our knowledge, this constitutes the first example of a protective effect of PEEP during permeability edema.
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We have studied the effects and mechanism of fenoterol (a beta 2-agonist) on contractility of the fatigued canine diaphragm. Transdiaphragmatic pressure (Pdi) was measured by a pair of balloons, and diaphragmatic contractility was assessed from changes in tetanic contraction, produced by supramaximal electrical stimulation of the phrenic nerves. Diaphragmatic fatigue was developed by applying an inspiratory resistive load to a spontaneously breathing dog for approximately 30 min. ⋯ Dibutyryl cyclic AMP did not have significant effect on the Pdi at all stimulation frequencies. The augmentation of Pdi in the fatigued diaphragm by fenoterol was abolished by administration of a calcium antagonist, verapamil, and fenoterol did not change the diaphragmatic contractility in nonfatigued dogs. We thus have concluded that fenoterol improves contractility in the fatigued canine diaphragm and the effect might be brought about by an increased influx of calcium to the muscle cell.