CHEMICAL CONTROL OF VENTILATION AND SLEEP ARTERIAL OXYGEN DESATURATION IN PATIENTS WITH COPD

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Abstract
In 41 patients with hypoxemic COPD [chronic obstructure pulmonary disease], nocturnal changes in arteril O2 saturation were compared to measurements of hypoxic and hypercapnic ventilatory control carried out during wakefulness. In 24 patients sleep was judged visually; in 17 sleep was staged by EEG. There were no differences between the 2 groups in terms of lung function, blood gases or sleep desaturation. All patients desaturated during sleep, with maximal desaturation occurring during rapid eye movement (REM) sleep. The maximal nocturnal change in O2 saturation in each patient was negatively correlated with that patient''s ventilatory sensitivity to hypercapnia; this relationship was independent of sleep stage. Maximal and mean nocturnal changes in O2 saturation were negatively correlated with O2 saturation during wakefulness. Hypoxic ventilatory response was not related to nocturnal desaturation. Patients sensitive to hypercapnia are unlikely to show major sleep desaturation; those insensitive to CO2 may do so, particularly if they have low O2 saturations while awake.