PMC6205802_01
Changes in the resting respiratory system resistance on the flow-volume curve at pre-BT and at 1 year after BT. The forced oscillation technique was used. Pre-BT, a semicircular flow-volume curve was detected in the expiratory phase (white zone), with the nadir (closed arrow) detected in the middle of the phase. At 1 year after BT, the flow-volume curve was changed to a triangular shape, with the nadir (open arrow) detected in the early expiratory phase. The gray zone represents the inspiratory phase. BT bronchial thermoplasty
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PMC6205802_01_13223_2018_276_Fig1_HTML.jpg
Fig1
At 1 year after BT, the resting tests for respiration showed no improvement in FEV1, but the forced oscillation technique (FOT) (MostGraph, Chest M.I., Tokyo, Japan) showed decreases in both inhalation and exhalation respiratory resistance values (Table 1 and Fig. 1).
Changes in the cardiopulmonary variables before and after BT. Changes in the ventilatory variables at pre-BT and at 3 months and 1 year after BT. Cardiopulmonary function was assessed by three procedures of incremental cardiopulmonary exercise testing using a similar treadmill protocol. BT bronchial thermoplasty, ex expiratory, fR breathing frequency, in inspiratory, Te expiratory time, Ti/Ttot the ratio of inspiratory time to total breathing cycle time,  minute ventilation,  oxygen uptake, VT tidal volume. Closed circle: pre-BT; open triangle: 3 months after BT; open circle: 1 year after BT
13223_2018_276_Fig2_HTML.jpg
PMC6205802_01_13223_2018_276_Fig2_HTML.jpg
Fig2
All the CPET results indicated that exercise was terminated when the target heart rate (THR), which was calculated as 220-age in years was reached; thereafter, the CPET results were evaluated (Table 2, Fig. 2). At the end of exercise, comparison of the findings at pre-BT and at 1 year after BT showed (1) improvement in dyspnea based on the Borg scale; (2) longer exercise time to reach the THR; and (3) increase in arterial oxygen saturation (SpO2).