Effects of indomethacin and hyperventilation on cerebral hemodynamics and oxygenation in newborn piglets.

We investigated the effect of indomethacin (INDO) and hyperventilation (HV) on cerebral hemodynamics and oxygenation in newborn piglets using near-infrared spectroscopy (NIRS). A total of 10 piglets aged 7-10 days were divided into 2 groups. INDO (Experimental group; 0.2 mg/kg i.v.) or saline (Control group) was administered after steady state, then each group was hyperventilated (pCO2; 20 mm Hg). Cerebral oxyhemoglobin concentrations (HbO2) significantly decreased immediately after INDO administration compared to controls (p < 0.01). This decrease continued for 15 min. During HV, HbO2 remained low compared to the steady state (p < 0.05) in the experimental group. Total hemoglobin concentrations (HbT) decreased simultaneously with HbO2. In the control group, no changes in HbO2 or HbT were observed after saline administration, and only a slight decrease in HbO2 was observed during the 5 minutes' HV compared to the steady state. No changes in cytochrome aa3 (Cytaa3) were observed in either group during 100% O2 inhalation. We conclude that INDO decreased HbO2 and HbT by vasoconstriction, but that HV did not further aggravate this tendency. Great care should be taken when using INDO for newborn neonates.