INHALED NITRIC OXIDE DOES NOT ACTIVATE SYSTEMIC INFLAMMATORY MARKERS IN PREMATURE LAMBS. |[dagger]| 1709

Inhalation of nitric oxide may be toxic, yet it is being increasingly used as a pulmonary vasodilator in infants with severe lung disease. To determine if inhaled nitric oxide (INO) causes an increase in systemic inflammatory markers, we measured neutrophil respiratory burst (NRB), spontaneous blastogenesis (SB), hemiallogeneic mixed lymphocyte reactivity (stimulation index; MLR-SI), and plasma interleukin-6 (IL-6) in premature lambs randomized to receive either INO or control gas. We studied six sets of premature lamb twins (119-126 days gestation, ≅ 0.8 term). Arterial and venous catheters, and tracheal tubes were placed and modified natural surfactant(beractant) was given prior to mechanical ventilation. Lambs were delivered, stabilized and mechanically ventilated for approximately two hours prior to obtaining samples for baseline inflammatory marker measurements. One twin was randomly assigned to receive 20 ppm INO while the other received control gas(Control) for the next four hours. Blood samples for inflammatory marker measurements were collected at two, three, and four hours of the study. There were no significant differences in the systemic inflammatory marker measurements between the INO and Control groups. Data intable are mean ± SE at baseline and two or four hours. We conclude that four hour INO administration does not cause systemic inflammatory marker activation in preterm lambs. These results may reflect the non-stimulated, immunosuppressed state of the surgically-delivered preterm animals.