The effect of positive end-expiratory pressure on regional pulmonary perfusion during acute lung injury.
OBJECTIVE
To determine whether positive end-expiratory pressure (PEEP) would change the altered regional pulmonary perfusion pattern caused by oleic acid (OA)-induced acute lung injury was the aim of this study. Our hypothesis was that fixed intravascular obstruction would not be affected by PEEP, leaving the perfusion pattern unchanged if this was the principal cause of perfusion redistribution after lung injury.


METHODS
Regional measurements of pulmonary perfusion and lung water concentration (LWC) were obtained both before and after lung injury and before and after PEEP (10 cm H2O) with the nuclear medicine imaging technique of positron emission tomography after injections of H2 15O in 7 supine anesthetized dogs. Four animals were also treated with meclofenamate to enhance perfusion redistribution after acute lung injury.


RESULTS
The application of PEEP before lung injury did not significantly affect the regional perfusion pattern. After administration of OA, LWC increased and fractional flow (without PEEP) decreased to the most edematous lung regions, consistent with perfusion redistribution. With the reapplication of PEEP, the perfusion pattern reverted toward the baseline pattern. The magnitude of this effect was roughly proportional to the effect of PEEP on regional inflation (r = .53), as evidenced by changes in LWC.


CONCLUSIONS
The reversibility with PEEP of the perfusion pattern caused by acute lung injury suggests that fixed intravascular obstruction is not the principal determinant of perfusion redistribution after OA-induced injury.
Schuster
D P
DP
Department of Internal Medicine, Washington University Medical School, St Louis, Missouri 63110.
Howard
D K
DK
D000208:Acute Disease; D000818:Animals; D004195:Disease Models, Animal; D004285:Dogs; D015633:Extravascular Lung Water / Q000000981:diagnostic imaging; D008469:Meclofenamic Acid / Q000494:pharmacology; D019301:Oleic Acid; D009829:Oleic Acids; D011175:Positive-Pressure Respiration / Q000009:adverse effects / Q000379:methods*; D011652:Pulmonary Circulation; D011654:Pulmonary Edema / Q000139:chemically induced / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000628:therapy*; D014055:Tomography, Emission-Computed
D009829:Oleic Acids; D019301:Oleic Acid; D008469:Meclofenamic Acid