hypoxia (nocturnal)

Last reviewed 01/2018

Nocturnal hypoxia is phenomenon which has been shown in patients with chronic bronchitis and emphysema who show severe arterial hypoxaemia. A marked nocturnal hypoxaemia occurs with a PaO2 as low as 2.5 kPa (19mm Hg) occurring - this is especially prominent during REM sleep.

Nocturnal hypoxaemic episodes are associated with a further rise in pulmonary arterial pressure and many of the deaths of patients with COAD occur at night, possibly due to cardiac arrhythmias.

An attack of nocturnal hypoxia normally causes the patient to awake. Thus patients with this condition suffer from daytime sleepiness.

Sleeping tablets must not be given because of a further depression in respiratory drive. Treatment is with nocturnal administration of oxygen.