Sleep-related hemodynamics and hypertension with partial or complete upper airway obstruction during sleep

Many different hemodynamic changes can be observed during obstructive apneas in the nocturnal sleep period. The most significant changes are observed whenever apneas occur in rapid succession. Systemic, pulmonary, and wedge pressure are modified. Many of these changes are mediated through cholinergic mechanisms. The mechanical effort of breathing against a partially or completely obstructed airway may also have an impact on hemodynamics. This impact must be dissociated from the impact of hypoxemia and blood gas changes. It has been questioned whether obstructive sleep apnea syndrome (OSAS) has any significant role in the development of 24-hour hypertension. In support of this theory, we found that tracheostomy does eliminate hypertension in obstructive sleep apneic children. In adults the issue is more complicated. Hypertension was eliminated in a subgroup of our patients treated with tracheostomy or nasal continuous positive airway pressure (CPAP), although the total group had no statistically significant blood pressure differences. Many variables that might dissociate treatment responders from nonresponders are not available. Hypertensive patients whose blood pressure normalized with OSAS treatment were significantly less overweight than the nonresponders in our series. Patients who remained hypertensive after treatment did, however, develop a normal circadian blood pressure trough during nocturnal sleep.