Respiratory patterns associated with hemoglobin desaturation during sleep in chronic obstructive pulmonary disease

Respiration during sleep was monitored in ten patients with chronic obstructive pulmonary disease (COPD) and related to measures of hemoglobin saturation and intrathoracic pressure (ITP) or abdominal wall movement. Seven of the ten patients showed episodic hemoglobin desaturation of at least 5 percent during sleep. Two distinct patient groups could be distinguished on the basis of ITP measurements and breathing patterns. Desaturation was associated with reduced negative ITP or respiratory movement in three patients and with increased negative ITP or respiratory movement in four patients. These data suggest that desaturation may result from at least two distinct mechanisms, involving reduced respiratory effort in one group and increased upper airway occlusion in the other. Desaturation associated with reduced respiratory effort was primarily REM-sleep related and consisted of a few sustained episodes. Desaturation episodes associated with upper airway occlusion occurred in all stages of sleep and were very frequent and of short duration.