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Regional pulmonary perfusion in patients with acute pulmonary edema
Daniel P Schuster1, Claire Anderson, James Kozlowski
1Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110-1093, USA. schusted@msnotes.wustl.edu
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Redistribution of pulmonary blood flow (PBF) away from edematous regions of the lung is characteristic of experimental acute lung injury (ALI), helping to preserve ventilation-perfusion matching and gas exchange. The purpose of this study was to determine if such perfusion redistribution occurs in acute pulmonary edema in humans.
Methods:
We measured the regional distribution of lung water concentration (LWC) and PBF with PET in 9 patients with ALI, 7 patients with non-ALI pulmonary edema, and 7 healthy subjects.
Results:
The average patient chest radiographic score was 7.5 +/- 2.2 (scale: 0-12, where > or =4 met our criterion for pulmonary edema). The mean partial pressure of oxygen, arterial/fraction of inspired oxygen ratio (PaO(2)/FIO(2)) was 192 +/- 78. LWC was 35 +/- 4 mL H(2)O/100 mL lung versus 20 +/- 5 mL H(2)O/100 mL lung in the healthy subjects (P < 0.05). On average, the ventral-to-dorsal regional distribution of PBF was similar in patients with pulmonary edema and healthy subjects, regardless of the etiology of the pulmonary edema. However, LWC and an index of perfusion redistribution away from edematous lung regions, when combined, were a significant determinant of the PaO(2)/FIO(2) (coefficient of determination [R2] = 0.53; P = 0.03).
Conclusion:
These results suggest that hypoxic vasoconstriction is severely blunted in ALI. The perfusion redistribution that does exist contributes slightly to improved oxygenation during early pulmonary edema in humans.