The effect of gavage feeding on the mechanics of the lung, chest wall, and diaphragm of preterm infants.

Preterm infants when given bolus nasogastric (gavage) feedings have well-characterized decreases in arterial partial pressure of oxygen, increases in arterial partial pressure of carbon dioxide, a tendency to have apnea, and are reported to have no change in the mechanics of breathing. The purpose of this study was to assess the function of the lungs, chest wall, and diaphragm in preterm infants without lung disease before and after gavage feeding. Lung mechanics were measured with a pneumotachograph and esophageal balloon, and the mechanics of the chest wall and diaphragm were assessed by inductance plethysmography and measurement of transdiaphragmatic pressure. After feeding, there was a significant decrease in dynamic lung compliance and increase in the minute ventilation (p less than 0.05). The work performed on the lungs was unchanged. The chest wall became more stable, with a significant decrease in its dynamic compliance (p less than 0.05). The diaphragmatic volume displacement, expressed as a percentage of the minute ventilation, was unchanged. The diaphragmatic work increased significantly (p less than 0.05), and was greater than four times the work performed on the lungs. These results are consistent with previous reports of a decrease in functional residual capacity after feeding. The mechanical stability of the chest wall may have been improved by an increase in the area of apposition of the diaphragm to it, or by an increase in the central drive to breathing after feeding.(ABSTRACT TRUNCATED AT 250 WORDS)