Comparison of 6-minute walking distance test due to different oxygen conserving devices

Background: Problems of oxygen conserving devices up to now include (1) poor synchronism of the inspiratory trigger, (2) FIO2 decreases as the respiratory rate increases, (3) waste of oxygen decreases compared with the constant flow, but FIO2 also decreases, (4) discomfort is appeared in high pulse dose. The new SmartDoze® is developed to automatically adjust the oxygen pulse dose according to the breathing rate and is automatically reduced the flow rate at rest. We compared the conventional oxygen conserving devices with SmartDoze® in 6 minutes walking distance (6MWD) test. Methods: The subjects were 25 patients (75.2 ±5.9 y/o, %VC82.7±19.0%, FEV1%42.3±19.5%, %FEV141.7±21.2%, PImax56.1±31.6cmH2O) with chronic respiratory insufficiency, with 20 cases of COPD, 5 cases of interstitial pneumonia. We compared arterial blood gas, pulse oximetry, respiratory rate, heart rate, blood pressure, dyspnea and lower limb muscle fatigue due to Borg scale before and after the 6MWD test. Results: The 6MWD by the conventional oxygen conserving was 289.6 ± 133m, and the 6MWD when using SmartDoze® was significantly improved to 314.1±123.9m (p Conclusions: SmartDoze® improves exercise tolerance, oxygenation and dyspnea by supplying an oxygen amount synchronized with an increase in respiratory rate at the time of exertion, and it seemed to be effective in pulmonary rehabilitation.