Validity of chronic obstructive pulmonary disease simulation using straws

Background: The experience of chronic obstructive pulmonary disease (COPD) can be simulated by breathing through straws. However, the simulated severity of COPD remains unclear. Objective: The purpose of this study was to clarify the validity of COPD simulation using straws. Methods: Ten young healthy men participated in the study. We measured forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), and airway resistance through bundles of 0 (baseline) to 5 straws that were placed between the mouth and the measuring device. Airway resistance was measured by using a forced oscillation technique and airway resistance at 5 Hz was used for the analysis. Results: Airway resistance was approximately 20× baseline (=no straw) when breathing through 1 straw, 12× baseline through 2 straws, 6× baseline through 3 straws, 4× baseline through 4 straws, and 3× baseline through 5 straws. FEV1/FVC was 21.5% when breathing through 1 straw, 42.2% through 2 straws, 59.3% through 3 straws, 67.2% through 4 straws, and 73.0% through 5 straws. FEV1% predicted was 23.5% when breathing through 1 straw, 45.6% through 2 straws, 66.0% through 3 straws, 77.3% through 4 straws, and 80.8% through 5 straws. FVC was not affected by the number of straws. Conclusion: Breathing through 4 straws mimicked Global initiative for chronic Obstructive Lung Disease (GOLD) stage 2 severity in healthy volunteers; breathing through 2 to 3 straws mimicked GOLD stage 3 severity, and breathing through 1 straw approximated GOLD stage 4 severity. It must be noted that the flow volume curve generated during disease simulation is different from that observed in actual COPD.