Effect of pulmonary artery pressure on extravascular lung water in an experimental model of acute lung injury.
BACKGROUND
Lung edema can be influenced by hemodynamic changes in pulmonary circulation. The aim of this study was to evaluate, in an experimental model of acute lung injury, the effect on extravascular lung water (EVLW) of an increase in pulmonary artery pressure (Ppa) without changes in cardiac output and wedge pressure.


METHODS
Lung edema was produced by an intravenous oleic acid infusion in mixed-breed pigs weighing 25-31 kg, which, after 20 min, were randomly assigned to a control group (100% FiO(2)) (n = 6) or a high Ppa group (21% FiO(2)) (n = 7). An increase in pulmonary artery pressure of at least 40% over baseline was produced in the high Ppa group by alveolar hypoxia. Hemodynamic, ventilatory and gas exchange parameters were collected at regular intervals. Pulmonary, wedge and capillary pressures were measured with a pulmonary artery catheter and the occlusion technique. EVLW was calculated gravimetrically.


RESULTS
At 240 min, both gravimetric-measured EVLW and mean pulmonary artery pressures were significantly higher (P < 0.05) in high Ppa animals vs. controls (12.06 +/- 4.21 vs. 7.98 +/- 2.46 ml/kg and 39.0 +/- 1.3 vs. 26.6 +/- 4.7 mmHg, respectively). Cardiac output (6.8 +/- 2.5 vs. 7.3 +/- 1.3) and pulmonary wedge pressures (9.2 +/- 1.7 vs. 9.4 +/- 2.8 mmHg) were similar. A difference was detected in pulmonary capillary pressures [17.0 +/- 3.3 (high Ppa) vs. 13.8 +/- 2.7 mmHg (controls)] but did not reach statistical significance.


CONCLUSIONS
In this model, an increase in pulmonary artery pressure by alveolar hypoxia produces an increase in extravascular lung water, probably related to changes in pulmonary capillary pressures.
Colmenero
M
M
Unidad de Medicina Intensiva, Servicio de Cuidados Crrticos y Urgencias, Hospital Universitario Virgen de las Nieves, Granada, Spain. macol@telefonica.net
Pérez Villares
J M
JM
Fernández Sacristán
M A
MA
Garcia Delgado
M
M
Fernández Mondéjar
E
E
D000208:Acute Disease; D000818:Animals; D002302:Cardiac Output / Q000502:physiology; D015633:Extravascular Lung Water / Q000502:physiology*; D006439:Hemodynamics / Q000502:physiology; D010100:Oxygen / Q000097:blood; D010865:Pilot Projects; D011654:Pulmonary Edema / Q000503:physiopathology*; D011659:Pulmonary Gas Exchange / Q000502:physiology; D011669:Pulmonary Wedge Pressure / Q000502:physiology*; D015656:Respiratory Mechanics / Q000502:physiology; D013552:Swine
D010100:Oxygen