ABSTRACT
AIM: Demand oxygen delivery systems (DODSs) were developed to secure the mobility of patients requiring oxygen therapy. The aim of the present study was to compare the efficacy of two currently available DODS with continuous oxygen administration (CONT). PATIENTS: Thirteen patients with COPD (mean [+/- SD] FEV1, 28 +/- 5.2% predicted; mean P(O2), 56.4 +/- 8.1 mm Hg [breathing room air]). INTERVENTION: Treatment for 30 min with CONT at a flow rate of 2 L/min, with the DODSs Oxytron 3 (Weinmann; Hamburg, Germany) or DeVilbiss EX 3000 (Somerset, PA) in random sequence. Arterialized blood samples were obtained from a hyperaemized ear lobe after 15 and 30 min. RESULTS: After 15 min, no significant differences in P(O2) or arterial oxygen saturation (Sa(O2)) were observed. In comparison with CONT (mean P(O2), 70.5 +/- 10.4 mm Hg; mean Sa(O2), 94.8 +/- 2.13%), oxygenation with the Oxytron 3 (mean P(O2), 66.3 +/- 10.3 mm Hg; mean Sa(O2), 93.5 +/- 2.6%) was significantly less after 30 min when measured independently by blood gas analysis and pulse oximetry. The DeVilbiss EX 3000 (mean P(O2), 69.1 +/- 12.0 mm Hg; mean Sa(O2), 94.5 +/- 3.2%) and CONT showed no differences. CONCLUSIONS: P(O2) did not reach equilibrium after 15 min of treatment with the DODSs. The titration of a patient to a DODS is recommended, since simply accepting the manufacturer's information on oxygen equivalent does not guarantee an adequate supply of oxygen.
