Effect of positive end-expiratory pressure on regional ventilation distribution during bronchoconstriction in XXXX studied by synchrotron radiation imaging.

@entity2507 @entity95 @entity112
OBJECTIVE: To assess the effects of positive end-expiratory pressure on regional ventilation distribution in normal lung and after @entity112 -induced bronchoconstriction. DESIGN: Experimental study. SETTING: International research laboratory. SUBJECTS: Six healthy @entity95 weighing 2.5    0.1 kg. INTERVENTIONS: @entity95 were anesthetized, tracheostomized, paralyzed, and mechanically ventilated. Synchrotron radiation computed tomography images of tissue density and specific ventilation were acquired using K-edge subtraction imaging with inhaled stable xenon gas in middle and caudal thoracic levels on 0 and 5 cm @entity2507 positive end-expiratory pressure at baseline and twice after @entity112 inhalation. MEASUREMENTS AND MAIN RESULTS: At baseline, a positive end-expiratory pressure of 5 cm @entity2507 significantly increased lung volume. @entity112 inhalation caused patchy areas of decreased specific ventilation, including some areas with no ventilation. After @entity112 , positive end-expiratory pressure significantly increased the area of well-ventilated lung regions and decreased the heterogeneity of specific ventilation. This improvement went together with a significant but limited increase in the area of hyperinflated lung zones. CONCLUSIONS: The findings of this study suggest that in mechanically ventilated @entity95 with severely heterogeneous bronchoconstriction, a positive end-expiratory pressure of 5 cm @entity2507 significantly improves regional ventilation homogeneity through dilation of flow-limited airways and recruitment of closed airways.
