[Behavior of arterial blood oxygen saturation at night in patients with obstructive lung diseases qualifying for home...

In COPD patients undergoing LTOT recent ATS and ERS guidelines suggest increase of oxygen flow by I L/min. to avoid severe desaturations during sleep. The aim of this study was to investigate frequency of overnight desaturations in COPD patients qualified for LTOT. We studied 101 consecutive COPD patients qualified for LTOT. Their functional characteristics were as follows: FVC = 2.24 +/- 0.78 L, FEVI = 0.88 +/- 0.39 L, PaO2 = 50 +/- 5 mmHg, PaCO2 = 48 +/- 8 mmHg. Overnight pulse oximetry was performed twice, while breathing air and on supplemental oxygen assuring satisfactory oxygenation (PaO2/O2 at rest when awake = 65 +/- 7 mmHg). We distinguished three groups of patients according to mean overnight arterial blood saturation breathing supplemental oxygen (mean SaO2/O2). First group - 40 patients (39.6%) had mean SaO2/O2 > 93% and time spent in saturation below 90% (T90/O2) = 4.5 +/- 6.7% of the recording time. Second group - 30 patients (29.7%) had mean SaO2/O2 between 90% and 92% and T90/O2 = 32.7 +/- 15.3%. Third group - 31 patients (30.6%) had mean SaO2/O2 < 90% and T90/O2 = 81.8 +/- 16.2% of the recording time. Comparison of ventilatory variables and daytime blood gases in these groups revealed statistically significant elevation of PaCO2 in group 3 (54 +/- 9 mmHg) compared to group 1 and 2 (45 +/- 6 mmHg and 47 +/- 7 mmHg respectively). FVCI, PaO2 and age were similar in all groups. We conclude that around 1/3 of COPD patients qualified for LTOT need increased oxygen flow during sleep. Such need should to be confirmed by the overnight pulse oximetry.