Prostaglandin and thromboxane levels during endotoxin-induced respiratory failure in pigs.

Arterial plasma concentrations of thromboxane B2 (TxB2), prostaglandin F2 alpha (PGF2 alpha) and 6-keto-prostaglandin F1 alpha (PGF1 alpha) were measured during endotoxin-induced acute respiratory failure (ARF) in anesthetized 10-12 wk old pigs. A 4.5 hour (hr) infusion of endotoxin resulted in a biphasic pattern of ARF. Phase 1 (0-2 hr) was characterized by increased pulmonary artery pressure, pulmonary vascular resistance (PVR), and alveolar-arterial O2 gradient (delta A-aO2), and decreased cardiac index (CI) and lung dynamic compliance (LDC). Following a return of PVR and CI values towards baseline, a second phase (2-4.5 hr) of deteriorating function occurred and was characterized by additional increases in PVR and delta A-aO2 and decreases in CI and LDC. Baseline (i.e., 0 hr) plasma TxB2 concentrations were 241 +/- 24 pg/ml; these values peaked at 0.5 hr (3228 +/- 712 pg/ml) and declined to 1635 +/- 453 pg/ml at 4.5 hr. Plasma concentrations of PGF2 alpha slowly increased from a baseline value of 154 +/- 32 pg/ml to 2355 +/- 738 pg/ml at 4.5 hr, while PGF1 alpha values increased from 54 +/- 2 pg/ml at 0 hr to 503 +/- 172 pg/ml at 4.5 hr. Time-matched control pigs showed no changes in pulmonary hemodynamics or in plasma TxB2, PGF2 alpha or PGF1 alpha levels. These results indicate that cyclooxygenase products are increased during both phases of endotoxin-induced ARF in pigs.