Pulmonary function tests (PFTs) are an integral component of the evaluation of patients with pulmonary diseases. 1 Due to concerns for virus transmission, multiple respiratory societies recommend to postpone or limit PFTs during the coronavirus disease 2019 pandemic. [2][3][4][5][6] Repeated forced breathing maneuvers during PFTs may generate bioaerosol by airway opening 7,8 or inducing cough. 1,7 However, the concentrations of particles that are generated and change over time during and after PFTs are unknown, leading to the current recommendation to close PFT laboratories for 20 minutes to 3 hours between tests. 2-4 Thus, we investigated aerosol particle generation and clearance during and after PFTs. MethodsThis prospective observational study was conducted in three PFT laboratories located at Rush University Medical Center (room size, 3 Â 3 Â 2.8 m), Rush Oak Park Hospital (room size, 3.6 Â 4.6 Â 2.8 m), and an outpatient clinic (room size, 3.4 Â 4.6 Â 2.8 m) with air exchange frequencies of five, three, and nine times/h, respectively. Adult patients whose condition required PFTs were enrolled after screening negative for coronavirus disease 2019. The study was approved, and informed consent was waived by the ethics committee at Rush University.

BACKGROUND: Pulse oximeters are used to measure S pO 2 and heart rate. These devices are either standalone machines or integrated into physiologic monitoring systems. Some smartphones now have pulse oximetry capabilities. Because it is possible that some patients might utilize this technology, we sought to assess the accuracy and usability of smartphone pulse oximeters. METHODS: This was a prospective, observational study that involved noninvasive measurements of S pO 2 and heart rate with 3 devices: Masimo Radical-7, Kenek Edge with the Apple iPhone 6S, and the Samsung S8 smartphone. Ambulatory adult patients visiting our institution's pulmonary function lab for a 6-min walk test were eligible to participate in the study. Pretest and posttest results for each subject were obtained simultaneously using all 3 devices. All results were analyzed with the Spearman rho correlation test, and Bland-Altman plots were used to assess the agreement of measures between the devices. RESULTS: Forty-seven subjects were enrolled in the study, with pulmonary hypertension (30%) and COPD (23%) being the 2 major diagnoses. The mean 6 SD difference between the Masimo and Apple devices for pretest S pO 2 was 2.3 6 2.4%, and the difference for posttest S pO 2 was 2.1 6 3.9%. The mean difference between the Masimo and Samsung devices for pretest S pO 2 was 3.2 6 2.8%, and the difference for posttest S pO 2 was 2.4 6 3.5%. The number of subjects who were unable to obtain S pO 2 was higher with the Samsung device than with the Apple device in both pretest (14 of 47 vs 3 of 47) and posttest (17 of 47 vs 5 of 47). In contrast, the Masimo device was able to measure S pO 2 in all subjects. CONCLUSIONS: Smartphone pulse oximeters were unreliable compared to a hospital pulse oximeter. Further research is needed with evolving technology to better understand smartphone pulse oximetry. (ClinicalTrials.gov registration NCT03534271.