PURPOSE: All carcinoma types can invade the trachea, and in more severe cases, it can be difficult to perform spirometry and CT due to the deterioration of forced expiratory volume and patients unable to execute the spine position. However, as impulse oscillometry (IOS) does not require any forced expiratory maneuvers, it is possible to assess patients incapable of forced expiratory maneuvers and evaluate the severity. We assessed the efficiency of IOS measurements before and after interventional bronchoscopy.
METHODS: IOS was performed before and after stenting in 14 patients with malignant tracheal stenosis from April 2008 to April 2010. The IOS measurements (resistance at 5Hz and 20Hz: R5, R20, reactance at 5Hz and 20Hz: X5, X20 and frequency of resonant: Fres) obtained from IOS were calculated at frequency ranges of 5Hz increments from 5Hz to 20 Hz at inspiratory and expiratory phases.
RESULTS: After stenting, airway patency was achieved for all patients with improvements in both R5 (0.38±0.13 kPa/(L/s)) and X5 (-0.15 kPa/(L/s)±0.06 kPa/(L/s)). Before stenting, all cases displayed values in R5 (0.66±0.33kPa/(L/s)) and values in X5 (-0.33±0.29 kPa/(L/s)). For severe cases, prior to treatment, R5-R20 increased (0.30±0.28 kPa/(L/s)) since impulses at 20Hz could not reach the peripheral airway due to tidal expiratory flow limitation. After stenting, the released tidal expiratory flow limitation allowed R5-R20 to decrease significantly (0.07±0.09 kPa/(L/s)).
CONCLUSION: In this study, IOS was useful in evaluating pulmonary functions before and after interventional bronchoscopy. We think R5-R20 can reflect the severity of tidal expiratory flow limitation for the malignant tracheal stenosis.
CLINICAL IMPLICATIONS: IOS can be a feasible examination for patients with severe tracheal stenosis, incapable of forced expiratory maneuvers.
DISCLOSURE: Hiroshi Handa, No Financial Disclosure Information; No Product/Research Disclosure Information