RESPIRATORY RESISTANCE MEASURED BY FLOW-INTERRUPTION IN A NORMAL POPULATION

Data on reference values of total respiratory resistance (R(int)) in h ealthy people are limited. The aim of this study was to examine the re lationship between R(int) and gender, height, weight, age and smoking habits. The instrument used was the Jaeger Pneumoscope with a flow int erruption device. The method is based on transient interruption of air flow at the mouth for a brief period during which alveolar pressure eq uilibrates with mouth pressure. Measurement of mouth pressure is used to estimate alveolar pressure prior to interruption. The ratio of this to the flow prior to interruption gives airway resistance. The R(int) data were correlated with height, weight, age, gender and smoking hab its in 172 healthy subjects. They had a normal lung function (VC, FEV( 1)) and no signs of pulmonary disease. The important determining facto r for the value of the R(int) were height and age. The mean R(int) of 172 subjects was 0.38 +/- 0.17 kPa.1(-1) s. The average within-subject variability of repeated measurements of R(int) expressed as coefficie nt of variation was 14.4 +/- 6.9%. Reference equation and normal value s for R(int) in a healthy population are related to height and age. Th e measurements were obtained with a commercially available interruptio n technique.