Plasma 6-keto prostaglandin F1 alpha and thromboxane B2 in sick preterm neonates.

To determine if vascular abnormalities in preterm neonates might be related to vasoactive prostaglandins, stable prostacyclin (6-KPGF1 alpha) and thromboxane A2 (T X B2) metabolites in arterial blood were measured at less than or equal to 6 hours after birth and at 24, 48, and 72 hours using a radioimmunoassay. Neonates of less than 32 weeks gestation (N = 26) were diagnosed as having either the idiopathic respiratory distress syndrome (IRDS, N = 15) or pulmonary edema (PE, N = 11), and were also grouped according to the presence or absence of intracranial hemorrhage (ICH, N = 11) or patent ductus arteriosus (PDA, N = 10). Initial plasma 6-KPGF1 alpha was greater in neonates with ICH (0.23 +/- 0.04 ng/ml, mean +/- SE) than without ICH (0.11 +/- 0.04, p less than 0.05). Neonates with both ICH and IRDS (N = 8) had significantly elevated T X B2 at all sampling times compared to neonates with IRDS and no ICH (N = 7). Both T X B2 and 6-KPGF1 alpha increased with time in those with major ICH. Among neonates without ICH, 7 with IRDS had higher initial 6-KPGF1 alpha (0.19 +/- 0.07 ng/ml) and lower T X B2 (0.15 +/- 0.04 ng/ml) than 8 with PE (0.04 +/- 0.01 and 0.37 +/- 0.09 ng/ml, respectively). The initial 6-KPGF1 alpha (0.024 + 0.003 ng/ml), measured in neonates with PE and without PDA or ICH (N = 6), was significantly less than the corresponding value in the other neonates (0.201 +/- 0.036 ng/ml) (N = 20).