The Role of Pulmonary Function Testing in Infants

Abstract

Tests of pulmonary function are used routinely in school-age and older children to augment or confirm clinical findings obtained by a careful history and physical examination. Spirometry allows both detection of airway obstruction even before wheezing can be heard and objective assessment of medical interventions. Measurement of lung volumes separates those processes that cause restriction from those that do not affect lung size or those that cause air trapping. Serial measurements have yielded important insights into the normal growth and aging of the lung as well as showing how various diseases affect lung and airway growth and repair. Although techniques to measure lung function in infants and toddlers have been available for more than 40 years, they have not been used clinically to the same degree that pulmonary function testing has been used in older children and adults. Possible reasons for infant pulmonary function testing not to be performed routinely relate both to the testing conditions and to the information gained. Chief among the former is the need to sedate all but the youngest infants to perform many of these studies. Both parents (1) and physicians (2) express concern over the need to sedate sick infants, even though the sedation typically is tolerated well. Some tests, such as respiratory inductive plethysmography or the forced oscillation technique, do not require sedation of the infant. Other procedural barriers include what must be done to the infant to obtain the necessary information. For example, measurements of dynamic pulmonary compliance and resistance require placement of an esophageal balloon or catheter and, therefore, are considered invasive. Forced expiratory flows by the rapid thoracic compression (“squeeze”) technique may appear uncomfortable for the infant, although infants do not demonstrate any physiologic signs of distress or discomfort during the testing. Some parents have expressed negative feelings after …