Evaluation of adherence to ambulatory liquid oxygen treatment: are commercialized dual-pressure transducers helpful?

Treatment adherence is widely recognized as a critical problem in long-term oxygen therapy, particularly in ambulatory liquid oxygen (LOX) systems. Adherence-monitoring strategies may be helpful in managing patients. We evaluated subjects' adherence to LOX using VisionOx and compared these results with the subjects' own adherence diaries and self-reported perceptions of use.

Patients using LOX were recruited for a clinical interview; the number of days/week and the mean time of use according to subjects' perceptions were recorded. A 14-day diary was provided for every subject while VisionOx was attached to the LOX. VisionOx is a small device that uses pressure transducers to detect oxygen flow and the subject's breathing frequency. Information is stored and downloaded using dedicated software.

Nineteen subjects were included (57.9% male with a median age of 63 years). When asked about the perception of LOX use, subjects self-reported using the device for a median of 100.0% of days (78.9% reported to have used it every day) for a median time of 180 min/day. According to data from VisionOx and subjects' diaries during the 14-day evaluation period, the median use was 92.8% of days for 210 min/day. No difference was found between the diaries and VisionOx data. Regarding subjects' perceptions of use, the declared use of LOX percent was significantly higher than reported in the diaries (P = .045) and VisionOx monitoring (P = .045) even though both underestimated the median use per day.

Subjects overestimated adherence to LOX therapy (when measuring percent of days of use) compared to adherence diary and objective adherence monitoring. Because no significant difference was found comparing the diaries and VisionOx use, either may be helpful in clinical practice.