In pediatric cystic fibrosis (CF) ambulatory care, handheld spirometry in individual clinic rooms would improve patient flow and potentially reduce patient‐to‐patient contact. A validation study was conducted to examine the accuracy of an entirely handheld turbine spirometer vs a standard laboratory device in pediatric CF patients.

Spirometric data were obtained from 76 CF patients aged less than 18 years in the ambulatory setting using the Micro Loop Spirometer (CareFusion) and compared to same‐day data from conventional laboratory spirometry.

Linear relationships were obtained between devices, demonstrating good correlation: r = .99, .99, .97, and .82 for forced expiratory volume in 1 second (FEV₁₎, forced vital capacity (FVC), FEF_25%‐75%, and peak expiratory flow, respectively (P < .001 for all). Biases (mean differences between devices) were −65 mL for FEV₁ (P < .001) and −115 mL for FVC (P < .001) on the handheld. Bland‐Altman plots demonstrated scatter in bias across all volumes. Limits of agreement (defined as mean ± 2 standard deviations [SD]) were large: +189 to −319 mL for FEV₁, equating to large limits of agreement for FEV₁ percent predicted of +9.0% to −13.9%. For repeated measurements on the same device on different days, a larger percent SD was obtained with the handheld compared to the conventional spirometer (6.7% vs 5.1%, respectively). Importantly, a relatively large number (15%) demonstrated a decrease in FEV₁ percent predicted of ≥10% on the handheld compared to conventional.

This suggests that while both devices have passed the recommendations for spirometry testing per American Thoracic Society/European Respiratory Society, handheld turbine vs conventional spirometers may not be used interchangeably in the pediatric CF population.