[Efficacy and patterns of ambulatory oxygen usage - experience of a university hospital]

To determine patterns of ambulatory oxygen (AO) use among patients with chronic obstructive pulmonary disease (COPD) and interstitial lung diseases, and analyze the effects of this therapy on daily activities and quality of life (QoL).

We included 37 consecutive adult patients on AO by liquid O(2) for more than three months prescribed by hospital pulmonologists. The acute response to O(2) was evaluated through the standardized 6-minutes walk test (6MWT) and the Borg dyspnea scale during the O(2) pre-intervention trial. Time spent away from home, compliance, side effects and QoL (SF-36 v1 questionnaire) were evaluated by a telephone interview during the follow-up period. Time spent away from home and QoL comparisons after and before the intervention were assessed retrospectively.

COPD was the most frequent diagnosis (54%), and 29 (78%) patients were already on long-term oxygen therapy. In relation to the acute response to O(2) evaluated through the 6MWT, there were significant improvements in the distance walked (p<0.001), in resting SatO(2) (p<0.001), in minimal SatO(2) (p<0.001), and in percentage of desaturation (p=0.002), independently of the diagnosis. No differences were observed in Borg dyspnea scale. AO was used for a mean of 4.1h/day. Patients spent fewer hours per day away from home after AO treatment (3.5h vs. 5.0h, p<0.025). Six patients (16%) were not compliant to the prescription, and 54% mentioned side effects. We verified low scores in almost all of the sub-domains of SF-36 QoL questionnaire, with a significant improvement noted only in role emotional (p=0.032). Improvement in health global state was described by 49% of patients.

Acute improvement in 6MWT parameters was not predictive of enhancement of outdoor activities and QoL with AO. More detailed studies are needed to achieve evidence based AO benefits.