Sleep apnea and pulmonary hypertension

Abstract

The pulmonary artery pressure values of 65 patients with sleep apnea syndrome were measured at rest and during ergometer exercise up to 100 W. Pulmonary hypertension at rest was found in 13, and during exercise in 31 more patients. Only 8 patients with pathological pressure findings suffered from pulmonary hypertension in combination with a pulmonary or cardiac disease. In the other 36 patients, no indication of a primary cause of pulmonary hypertension apart from sleep apnea syndrome could be found. Out of the 65 patients, 11 with a finding of more than 20 apnea episodes per hour's sleep underwent polysomnographic recordings in the sleep laboratory. The hemodynamic parameters were continuously measured. All 11 patients had a finding of severe sleep apnea with more than 300 apnea episodes during the night of recording. In 6 patients, the appearance of apnea episodes was accompanied by only moderate changes in pulmonary artery pressure. In 5 patients, there were critical increases in pulmonary artery pressure, which went along with increases in cardiac output and in pulmonary capillary wedge pressure. Increases in pulmonary vascular resistance were established in 3 out of these 5 patients, and a slight decrease in 2. The mechanism of hypoxic vasoconstriction of the pulmonary arteries may account for the pressure increases in 3 of our patients, but fails to explain the findings in the other 2 patients. Nocturnal changes in pulmonary artery pressure in patients with sleep apnea may therefore have different causes. Pulmonary hypertension constitutes a severe complication in patients with sleep apnea.(ABSTRACT TRUNCATED AT 250 WORDS)