THE ADEQUACY OF OXYGENATION IN COPD PATIENTS UNDERGOING LONG-TERM OXYGEN-THERAPY ASSESSED BY PULSE OXIMETRY AT HOME

It is probable that some daily activities may cause marked falls in arterial oxygen saturation (Sao(2)) in patients undergoing long-term oxygen therapy (LTOT), despite good oxygenation at rest. We estimated the adequacy of LTOT in 34 randomly selected chronic obstructive pulmonary disease (COPD) patients at home by monitoring Sao(2) continuously over 24 h. The subjects were also asked to complete a questionnaire listing frequent daily activities. Despite almost normal mean Sao(2) (94%) at the beginning of recording (O-2 2 l.min(-1), at rest) the subjects studied spent 6.9 h below an Sao(2) of 90%, with minimum Sao(2) of 61%. On average we observed 10 episodes of desaturation in each patient over 24 h, both white breathing air and oxygen. The comparison of Sao(2) recordings and questionnaires revealed the highest number of desaturations during sleep, followed by naps, watching the television, eating, washing and talking. The oxygen flow rate prescribed, based on blood gas measurements at rest, did not protect 85% of the patients studied from deep falls in Sao(2) during daily life. An increase of oxygen flow during some activities and during sleep is suggested.