Serial pulmonary vascular pressures and cardiac volumes, filling pressures, output, and heart rates. Serial cardiopulmonary parameters comparing 42-day-old (closed circle, solid line) and 7-day-old (open circle, dashed line) transfused blood. Measures of pulmonary vasoconstriction in animals (A-B) significantly increased after transfusion of 42- compared with 7-day-old stored blood (P = .02 for both) at 24 hours. This greater increase in 42-day-old blood mPAP was associated with a reduced cardiac end diastolic (E, P = .01) and end systolic (F, P = .02) volume index and a subsequent decrease in stroke volume index (D, P = .04) compared with 7-day-old blood. The decrease in these indexes coincided in a significant increased heart rate (C) with older blood at 24 hours (P = .003) that remained elevated to 48 hours (P = .04) resulting in a similar cardiac index (G, P = NS) between treatment groups. Pulmonary artery occlusion pressures (H) were not significantly different after transfusion of 42- compared with 7-day-old transfused blood (P = NS). Data presented as mean ± SE.