The NAEPP (National Asthma Education and Prevention Program) guidelines recommend that spirometry be performed on patients with asthma because they serve as an objective measure of airway obstruction. Unfortunately, most children under 5 years of age are unable to perform a forced expiratory maneuver making conventional spirometry unavailable in this age group in most venues. Furthermore, other population groups such as retarded people, elderly or physically handicapped share the same difficulty.