The effect of inhaled nitric oxide on splanchnic perfusion in a neonatal piglet model.

BACKGROUND

Inhaled nitric oxide (iNO) is a commonly used pulmonary vasodilator in neonates, but its effects on intestinal perfusion remain unclear. This study assessed the impact of iNO on splanchnic tissue oxygenation as a surrogate for intestinal perfusion using near infrared spectroscopy (NIRS), with NG-nitro-L-arginine methyl ester (L-NAME) used to inhibit endogenous nitric oxide synthase (NOS) and isolate the effect of exogenous NO.

METHODS

Seventeen piglets (7-10 days old) were anesthetized and ventilated with NIRS probes placed on the forehead and abdomen. Piglets were allocated to group 1 (n = 4) receiving iNO only, group 2 (n = 6) receiving iNO then L-NAME, and group 3 (n = 7) receiving L-NAME then iNO. Serum nitrate/nitrite and endothelin-1 expression were assessed via colorimetric assay and ELISA.

RESULTS

iNO increased splanchnic oxygenation, significantly reducing the difference between cerebral and abdominal NIRS. This effect was blunted by L-NAME pre-treatment (p = 0.02 at 0 and 60 ppm). Serum nitrate/nitrite and endothelin-1 levels did not differ significantly between groups, nor did mean arterial pressure.

CONCLUSION

iNO enhances splanchnic tissue oxygenation to near cerebral levels. Pretreatment with L-NAME eliminates this effect, suggesting a role for endogenous NOS in this process. These findings suggest a potential protective role of iNO against intestinal ischemia and merit further investigation.

IMPACT: As shown in previous studies, there are extrapulmonary effects of inhaled nitric oxide (iNO) on tissue perfusion; this study specifically validates this by evaluating oxygenation of the gut. iNO increases splanchnic tissue oxygenation to cerebral levels. This preclinical research establishes improvement in intestinal oxygenation with iNO use in contrast to other studies proposing iNO as a potential contributor to the development of NEC in the setting of cardiac defects. This study suggests that iNO could be a potential therapeutic agent in ischemic intestinal conditions.