Comparison of PEFR and FEV1 in Patients with Varying Degrees of Airway Obstruction: Materials and Methods
All testing was performed at an altitude of approximately 1,606 m. Each patient performed three maneuvers with each instrument in an alternating fashion. The FEV, and PEFR obtained with the JPF as well a PEFR obtained with the WPF were converted to percent predicted, using normal standards for ventilatory function. In addition, absolute values of FEV„ JPF, and WPF were compared. Studies with 60 normal subjects in our laboratory demonstrated that the predicted values of Knudson et al correlated best with the equipment used. Therefore, all data reported are based on those authors’ predicted values.
Effect of Altitude
Each subject performed three maneuvers in an atmospheric chamber at simulated altitudes of sea level, 757.5, 1,515, and 2,272 m. Peak flow, FVC, and FEV, were recorded with a Jones Pulmonor Datamatic Spirometer, and the best effort for each subject was used for comparison. Forced expiratory efforts at the different altitudes were performed at approximately 20-min intervals and BTPS correction made. buy-asthma-inhalers-online.com
The correlation between FEV, and PEFR were assessed using the Statistical Package for the Social Sciences (SPSS). The FEV„ WPF, and JPF were compared using analysis of variance and the Newman-Keuls multiple comparisons procedure.
One hundred two patients participated in the study: 43 males and 59 females. Their ages ranged from 9 to 70 years, with a mean of 35.3 years. Seventy-one patients had diagnoses of airway obstruction. Sixty-one patients were judged to have hyperreactive airways disease based on a 15 percent increase in FEVt either spontaneously or following bronchodilator administration (n=46), a positive methylcholine challenge test (n = ll), or bronchospasm in response to exercise challenge (n = 4).