Medical therapy of heart failure or heart transplantation may correct disordered breathing. Periodic breathing may also be overridden by mechanical ventilatory support at night. Irregular breathing may occur when there are irregular transitions between wakefulness and sleep from sleep disruption. Deep breaths during arousal may produce apneas or hypopneas by lowering PC02 or by vagal mechanisms. Top of page Altered breathing during sleep affects cardiovascular status Alterations in breathing pattern and gas exchange during sleep affect the cardiovascular system.
Apneas slow the heart rate and can produce transient asystoles.
Periods of upper airway obstruction lower cardiac output and delivery of oxygen to tissues. Hypoxemia, hypercapnia, and perhaps arousals increase sympathetic activity which raises blood pressure and may contribute to ventricular dysrhythmias. Hypoxemia and hypercapnia also constrict the pulmonary arteries and may cause right ventricular dysfunction. Periodic breathing during sleep commonly accompanies severe left ventricular dysfunction, is predictive of mortality in heart failure, and is treatable with CPAP and probably oxygen. Top of page Summary Sleep impairs breathing effort and alters both the volume of ventilation and stability of breathing pattern.