[Usefulness of twenty-four-hour home monitoring of oxygen saturation in patients with chronic obstructive pulmonary disease].

The clinical usefulness of 24 hr home monitoring of oxygen saturation (SaO2) with pulse oximeter was studied in 48 outpatients with COPD. In addition, doppler echocardiography for measurement of acceleration time (AcT), which inversely correlates with mean pulmonary arterial pressure, a 6-minute walk test, and an exercise study on a bicycle ergometer were performed in 26, 17, and 14 patients, respectively. Nadir SaO2 and the total time during which SaO2 was below 90% were calculated to estimate diurnal and nocturnal oxygen desaturation (diurnal nadir SaO2, diurnal TSaO2 < 90%, nocturnal nadir SaO2, and nocturnal TSaO2 < 90%). Relations between the indices of desaturation measured during home monitoring and dyspnea grade (Fletcher-Hugh-Jones), awake PaO2, AcT, Hb, Ht, and oxygen desaturation during the exercise tests were also studied. Diurnal nadir SaO2 was lowest and diurnal TSaO2 < 90% was longest in the group with dyspnea grade IV. In the other groups, various degrees of oxygen desaturation were observed, even within groups. Diurnal nadir SaO2 and nocturnal nadir SaO2 correlated with awake PaO2, but not with diurnal TSoO2 < 90%. Diurnal nadir SaO2 was similar to nadir SaO2 during the exercise tests. AcT, hemoglobin, and hematocrit correlated with diurnal oxygen desaturation but not with nocturnal oxygen desaturation. From the above findings, we conclude that pulmonary hypertension may be associated with diurnal oxygen desaturation, and that home monitoring of SaO2 is useful for the detection of oxygen desaturation not predicted from dyspnea grade and PaO2 while awake.