Spirometry (pre- and postbronchodilator) was assessed using a flow-sensitive spirometer (Renaissance II; Puritann-Bennett, Carlsbad, CA). A respiratory therapist who was experienced in performing spirometry in children conducted all tests, and all tests conformed to the criteria of the American Thoracic Society. All tests were performed between 10 a.m. and 2 p.m. The following parameters were measured: forced vital capacity (FVC), forced expiratory volume in 1 second (FEVi) and forced expiratory flow at midlung volume (FEF25-75). The ratio of FEVi to FVC (FEVi/FVC) was calculated. All values were adjusted for body temperature and barometric pressure. Percent predicted values for FVC,
Table 1. Questionnaires used to elicit symptoms
FEVi and FEF25-75 were calculated from reference values based on the Harvard six-cities study. Subjects were asked to refrain from use of asthma medications for 24 hours before testing. Before use of an inhaled bronchodilator, the best three of five forced expiratory maneuvers were recorded. Acute bron-chodilatation was achieved with inhalation of two puffs (90 |ngm each) of albuterol metered-dose inhaler (Ventoline; GlaxoSmithKline, Research Triangle Park, NC) delivered via a spacer (Opticham-ber Advantage; Respironics, Cedar Grove, NJ). Ten minutes later, spirometry was repeated, with no more than five attempts made to obtain three acceptable forced expiratory maneuvers. All maneuvers were done in the standing position, with a nose clip in place. A single observer for the quality of the FEVi and FVC reviewed all studies. Asthma was defined as FEVi <80% predicted and FEVi/FVC >5% lower than predicted for age and sex. Source your medication needs online. Canadian viagra home delivered
Values are presented as mean ± standard deviation. Chi-squared analysis was used for nominal data, and unpaired t-tests were used for continuous data. Statistical significance was assumed when the p value was <0.05.