Reduction of immunoreactive prostacyclin metabolite after paralysis in ventilated preterm infants.

Levels of the stable metabolite of prostacyclin, 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) were measured by radioimmunoassay during the first 48 hours of life in a group of 20 infants ventilated for the respiratory distress syndrome in whom a simultaneous record of respiratory activity was made. 6-Keto-PGF1 alpha was significantly lower when the infants were paralysed (P = 0.0004) than when they were breathing spontaneously. Elimination of the capacity for spontaneous respiration may reduce barotrauma and hence the stimulus for prostacyclin release from the lung.