Why is obstructive sleep apnea (OSA) a cardiovascular risk factor?

Patients with obstructive sleep apnea (OSA) frequently suffer from cardiovascular diseases. Mechanisms like intrathoracic pressure variations, changes in blood gases (hypoxia), arousals and neurohumeral adaption mechanisms, combined with breathing disorders are causing these cardiovascular sequelae. In particular repetitive hypoxemia and activation of the sympathetic nervous system have to be considered as stressors for the cardiovascular system. Special clinical findings should take OSA into consideration as a differential diagnosis. A systematic anamnesis with questions to daytime conditions (hypersomnia, decrease of performance), snoring and apneas while sleeping is easy to ascertain, and will lead to the correct diagnosis in more than 90% of cases. The extent and need for therapy should be assessed by three criteria: 1) daytime symptoms, 2) the extent of breathing disorder and 3) cardiovascular comorbidity.