NO administered by inhalation dilates pulmonary circulation of the neonate. Since its effects on systemic circulation are not known, we gave Survanta and we mechanically ventilated 5 preterm lambs (0.83 of gestation) to whom we administered 20 ppm of NO por 4.5h, after 1.5h of basal time. Five lambs were their controls (C). Systemic (SAP) and pulmonary (PAP) arterial pressure, blood gases, cardiac output (CO) and cerebral blood flow (CBF) (radiolabelled microspheres) were measured basally and at 1 and 2h with or without NO administration (NO and C groups, respectively). The results were (means± SEM;*p<0.05 NO vs. C and NO basal vs. NO 1h).Table

Table 1
Full size table

We conclude that NO inhalatory administration decreased trasiently the cerebral blood flow, effect associated to other hemodynamic changes or PCO variations. (Supported by U. Chile, U. North Carolina and AGA Chile).