Arterial oxygenation during sleep in patients with right-to-left cardiac or intrapulmonary shunts.

Publisher Website
Google Scholar
Abstract
Arterial oxygen saturation (SaO2), breathing patterns and EEG sleep stage were studied during nocturnal sleep in 6 patients with right-to-left cardiac or intrapulmonary shunts and 6 patients with chronic bronchitis and emphysema, chosen because they were equally hypoxemic when awake (SaO2 during wakefulness: bronchitis 74-90%, mean 83%; shunt 77-89%, mean 83%). The patients with bronchitis had far greater falls in SaO2 when asleep than those with shunts (maximum fall in SaO2 during sleep: bronchitis 14-47%, mean 29%; shunt 5-10%, mean 8%; P < 0.01). Significant episodes of hypoxemia (defined as SaO2 falls > 10%) occurred in all 6 bronchitic patients, from 1-7 times per night, but in none of the patients with shunts (P < 0.05). Of the 27 episodes of hypoxemia, 24 occurred in rapid eye movement (REM) sleep and 24 were associated with hypopnea. The 2 groups of patients had similar EEG sleep patterns and the same amount of hypopnea during sleep. Arterial level oxygenation when the patient is awake is not the sole determinant of the degree of nocturnal hypoxemia; the pathological process is also important.