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Am J Respir Crit Care Med. 2011 May 1;183(9):1193-9. doi: 10.1164/rccm.201008-1318OC. Epub 2011 Jan 21.

Lung regional metabolic activity and gas volume changes induced by tidal ventilation in patients with acute lung injury.

Author information

1
Department of Experimental Medicine (DIMS), University of Milan-Bicocca, Via Cadore 48, 20052 Monza (MB) Italy.

Abstract

RATIONALE:

During acute lung injury (ALI), mechanical ventilation can aggravate inflammation by promoting alveolar distension and cyclic recruitment-derecruitment. As an estimate of the intensity of inflammation, metabolic activity can be measured by positron emission tomography imaging of [(18)F]fluoro-2-deoxy-D-glucose.

OBJECTIVES:

To assess the relationship between gas volume changes induced by tidal ventilation and pulmonary metabolic activity in patients with ALI.

METHODS:

In 13 mechanically ventilated patients with ALI and relatively high positive end-expiratory pressure, we performed a positron emission tomography scan of the chest and three computed tomography scans: at mean airway pressure, end-expiration, and end-inspiration. Metabolic activity was measured from the [(18)F]fluoro-2-deoxy-D-glucose uptake rate. The computed tomography scans were used to classify lung regions as derecruited throughout the respiratory cycle, undergoing recruitment-derecruitment, and normally aerated.

MEASUREMENTS AND MAIN RESULTS:

Metabolic activity of normally aerated lung was positively correlated both with plateau pressure, showing a pronounced increase above 26 to 27 cm H(2)O, and with regional Vt normalized by end-expiratory lung gas volume. This relationship did not appear to be caused by a higher underlying parenchymal metabolic activity in patients with higher plateau pressure. Regions undergoing cyclic recruitment-derecruitment did not have higher metabolic activity than those collapsed throughout the respiratory cycle.

CONCLUSIONS:

In patients with ALI managed with relatively high end-expiratory pressure, metabolic activity of aerated regions was associated with both plateau pressure and regional Vt normalized by end-expiratory lung gas volume, whereas no association was found between cyclic recruitment-derecruitment and increased metabolic activity.

Comment in

PMID:
21257791
PMCID:
PMC3114052
DOI:
10.1164/rccm.201008-1318OC
[Indexed for MEDLINE]
Free PMC Article

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