Nocturnal oxygen desaturation is a frequent complication in portopulmonary hypertension

Nocturnal oxygen desaturations (NOS) are a common feature in patients with idiopathic pulmonary arterial hypertension. In patients with portopulmonary hypertension (PPHT), the frequency, degree and potential causes of NOS are unknown.

We retrospectively analyzed patients with PPHT, in whom right heart catheterization, pulmonary function testing, measurements of arterial oxygen tension (paO(2)) during daytime both at rest and at maximum physical exercise on cycle ergometer, and nocturnal polygraphy including pulse oximetry were performed. The data of these examinations were analyzed.

Six patients with moderate to severe PPHT were included. Mean pulmonary artery pressure was 50+/-8 mmHg. Lung function did not reveal relevant pathological findings. Pulse oximetry demonstrated moderate to severe NOS as classified by duration of oxygen desaturation <90 % in 5 patients. Mean paO(2) at rest and during maximum exercise was 10.6+/-1.2 kPa and 9.2+/-1.6 kPa, respectively. One of 5 patients with moderate to severe NOS demonstrated exertional hypoxemia with a paO(2) value of <8.0 kPa. None of the patients showed sleep apnea.

Moderate to severe nocturnal hypoxemia seems to be common and is not related to sleep apnoea and lung function in patients with PPHT. The absence of exertional hypoxemia does not exclude NOS. We recommend to perform overnight oximetry in the routine examination of PPHT patients because nocturnal oxygen supplementation should be considered in patients with NOS.