Newborn piglets with meconium aspiration resuscitated with room air or 100% oxygen.

We investigated whether newborn piglets exposed to hypoxemia and severe meconium aspiration could be reoxygenated with room air as efficiently as with 100% O(2). Twenty-one 2- to 5-d-old piglets were randomly divided into three groups: 1) the room air group: hypoxemia, meconium aspiration, and reoxygenation with room air (n = 8); 2) the O(2) group: hypoxemia, meconium aspiration, and reoxygenation with 100% O(2) (n = 8); and 3) the control group: meconium aspiration, and reoxygenation with room air (n = 5). Hypoxemia was induced by ventilation with 8% O(2) until the mean blood pressure reached <20 mm Hg or the base excess reached <-20 mM. At this point, reoxygenation was started with either room air or 100% O(2). Three milliliters per kilogram of meconium 110 mg/mL was instilled into the trachea immediately before the start of reoxygenation. The O(2) tension in arterial blood was significantly lower in the room air group; at 5 min of reoxygenation it was 9.1 +/- 0.5 kPa versus 43.5 +/- 6 kPa in the O(2) group (p < 0.05). At 5 min of reoxygenation the tidal volume per kilogram was 12.1 +/- 0.7 mL/kg in the room air group and 13.1 +/- 0.9 mL/kg in the O(2) group (NS). There were no significant differences between the room air and the O(2) groups during 120 min of reoxygenation in mean arterial blood pressure, pulmonary arterial pressure, cardiac index, base excess, or plasma hypoxanthine. In conclusion, hypoxic newborn piglets with meconium aspiration were found to be reoxygenated as efficiently with room air as with 100% O(2).