An Evaluation of Incentive Inspirometers for Following Pulmonary Function by Self-Measurement in the Home

Measurements of inspired vital capacity made with two commercially available, inexpensive incentive inspirometers (Voldyne, Volurex) have been compared to standard expired forced vital capacity (FVC) measured by spirometry in the pulmonary function laboratory. Reliability of self-measurement made at home with these devices was also studied. There were 119 subjects in this study with an average age of 14.1 years, (4–44 years). Home and clinic Voldyne measurements were highly correlated (r = 0.96). There were no statistically significant differences between paired measurements. Although differences between inspired vital capacity using either device and FVC were significant (p < 0.001), inspired vital capacity was strongly correlated with FVC (r = 0.83 for Voldyne, r = 0.90 for Volurex). Subjects can make reliable measurements of lung capacity at home with inexpensive devices. These measurements are linearly related to standard FVC and can thus provide trend information on lung function over long time periods from an ambulatory setting. Such measurements have been used for tracking lung function in cystic fibrosis, and may be applicable in other chronic pulmonary diseases.