Abstract
In France, 12,000 patients receive long-term oxygen therapy at home supplied by oxygen concentrators (OCs) which are provided by a non-profit organization, the National Home Treatment for Respiratory Insufficiency Association (ANTADIR--31 regional associations). OCs are regularly checked at home by technicians from the associations. Technical data, oxygen fraction (Fo2) supplied at working flow-rate and working duration, were recorded by technicians only during the planned home controls. Data were collected from January 15th to February 15th, 1988. Twenty three associations taking care of more than 10,000 OCs participated in the study. 2,414 machines of six different brands were controlled in the study. 77.5% of OCs had a working duration of less than 15,000 h (about 3 yrs). Working flow-rate of OCs was equal to or lower than 2 l.min-1 in 79.2% of cases. Mean Fo2 of the 2,414 measurements was equal to 92 +/- 6%. Three quarters of OCs had an Fo2 equal to or higher than the Fo2 predicted by the manufacturers. Less than 0.3% of machines were out of order (Fo2 less than or equal to 50%). We observed a significant progressive decrease in measured Fo2 in relation to flow-rate and working duration (analysis of variance (ANOVA) 2: p less than 0.001): the higher the flow-rate and the longer the working duration, the lower the Fo2. We conclude that supply of used OCs has to be avoided when the prescribed flow-rate is high, and that systematic technical checks are essential to keep OCs in good working order.
