A new method of expired gas collection for the measurement of breath hydrogen (H2) in infants and small children.

The measurement of hydrogen (H2) in breath is becoming increasingly useful as a diagnostic and research tool, but there is still no satisfactory method of sampling expired air in infants and small children. We tested a modified open-flow hood method where the child's head is put in a perspex box and expired air is collected by sucking air from the box by means of an air pump. Comparison of this method with end-expiratory sampling by a modified Haldane-Priestly and nasopharyngeal catheter gave a correlation coefficient of 0.83 and 0.65, respectively. We conclude that expired air sampling in children with this method is a more satisfactory and as reliable a method as any available at present, and has the added advantage of being quantitative.