Physiological outcomes.

The degree of airway obstruction, as well as airway responsiveness, can be quantified in infants and pre-school children by several different physiological measurements. These measurements include forced expiratory flows, resistance, tidal flow volume indices, transcutaneous oxygen, and lung sounds. These different measurements have been applied to assess lung growth, respiratory epidemiology, airway reactivity, and the effectiveness of therapeutic interventions. Additional research is required to establish normative data, to relate physiological measurements to clinical symptoms, and to compare the information obtained from the different measurements. In addition, there is a need to develop alternative methodologies that avoid sedation of infants and minimise the degree of cooperation required of preschool children.