SESSION TYPE: Physiology/PFTs/ Rehabilitation I
PRESENTED ON: Sunday, October 21, 2012 at 01:15 PM - 02:45 PM
PURPOSE: Both Airflow Perturbation Device (APD) and Impulse Oscillometry (IOS) are devices developed to measure airway resistance. Each utilizes very different methodologies. Limited data exist comparing the devices, particularly in patients with abnormal pulmonary function. This study examines how the two devices compare both with each other and standard spirometry.
METHODS: Consecutive patients referred for pulmonary function testing were asked to consent to additional testing with APD and IOS. Subjects were seated, nose clips applied, and airflow was measured during normal tidal breathing through an antimicrobial filter mouthpiece. With APD, airflow is perturbed by a rotating wheel which briefly interrupts airflow at a frequency of 10 Hz. The mouth pressure to airflow ratio is used to calculate inspiratory and expiratory airway resistances. IOS analyses the reflection of pressure impulses of 5 - 20 Hz.
RESULTS: Forty eight subjects enrolled. Male:female ratio was 15:33. Three African-American and 45 Caucasians were tested; 34 patients were current or former smokers. Average BMI was 30.2 ± 6.7 (mean ± SD, range 17.7 - 42.4) and average age was 61 ± 11 years (range 37 - 86). Baseline spirometric values: mean FVC of 85% predicted ± 22, mean FEV1 of 84% predicted ± 30, FEV1/FVC of 70% ± 16. Average APD inspiratory resistance (APD ins) and expiratory resistance (APD exp) correlated well with R5 (R2= 0.802). APD exp correlated more strongly with R5 than APD ins. There was no correlation between APD exp-APD ins and AX (area of reactance) and very weak correlation with Fres (Resonant Frequency) (R2 = 0.17). APD and IOS correlated only weakly with spirometric values.
CONCLUSIONS: APD and IOS demonstrated strong correlation in a spectrum of patients with normal lung function and restrictive and obstructive lung disease. These airflow resistance measurements were not well predicted by spirometry.
CLINICAL IMPLICATIONS: As a quick and effort independent test that correlates well with IOS, APD has the potential to provide easily obtained, useful information regarding lung function status not available through spirometry.
DISCLOSURE: The following authors have nothing to disclose: Peter Whitesell, John Whitesell, Jafar Vossoughi, Arthur Johnson
No Product/Research Disclosure InformationShore Health Systems, Easton, MD