ULTRASONOGRAPHIC ASSESSMENT OF INTRAGASTRIC VOLUME IN NEONATES - FACTORS AFFECTING THE RELATIONSHIP BETWEEN INTRAGASTRIC VOLUME AND ANTRAL CROSS-SECTIONAL AREA

Measuring antral cross-sectional area by ultrasonography can be an ide al way to evaluate intragastric milk volume in infants. Technical deta ils, however, remain to be established before its clinical application . We investigated the effects of posture and ultrasonographic plane on the correlation between milk volume and antral cross-sectional area. After gastric aspiration through a nasogastric tube, healthy newborns were fed 0, 10, 20, and 40 mi of milk cumulatively, and antral cross-s ectional area was measured in either upright, sitting, or right latera l position. To determine the best sonographic plane, subjects were put in the right lateral position and antral cross-sectional area was mea sured in the plane of the aorta and either the superior mesenteric art ery, the superior mesenteric vein, the midline of the abdominal surfac e, 1 cm right of midline, or 2 cm right of midline. The results showed that antral cross-sectional area reflects intragastric milk volume mo st accurately, with minimal gas interference when measured in the righ t lateral position. The area correlates well with milk volume in the p lane of the aorta and either the superior mesenteric artery, the super ior mesenteric vein, or the midline. Next, we studied the effect of in tragastric gas on the antral cross-sectional area in subjects who were given 40 mi of milk followed by an injection of air. More than 20 mi of intragastric gas increases antral cross-sectional area significantl y. Ultrasonographic evaluation of intragastric volume requires attenti on to the above factors.