Continuous Positive Airway Pressure for the Treatment of Supine Hypertension and Orthostatic Hypotension in Autonomic Failure

BACKGROUND: Supine hypertension affects most patients with orthostatic hypotension (OH) due to autonomic failure, but it is often untreated for fear of worsening OH. We hypothesized that increasing intrathoracic pressure with continuous positive airway pressure (CPAP) had a Valsalva-like blood-pressure-lowering effect that could be used to treat nocturnal supine hypertension in these patients, while reducing nocturnal pressure diuresis and improving daytime OH.METHODS: In Protocol 1, we determined the acute hemodynamic effects of increasing levels of CPAP (0, 4, 8, 12, and 16 cm H2O, 3 minutes each) in 26 patients with autonomic failure and supine hypertension studied while awake and supine. In Protocol 2 (n=11), we compared the effects of overnight therapy with CPAP (8-12 cm H2O for 8 hours) versus placebo on nocturnal supine hypertension, nocturnal diuresis and daytime OH in a 2-night crossover study.RESULTS: In Protocol 1, acute CPAP (4-16 cm H2O) decreased systolic blood pressure in a dose-dependent manner (maximal drop 22 +/- 4 mmHg with CPAP 16) due to reductions in stroke volume (-16+3%) and cardiac output (-14 +/- 3%). Systemic vascular resistance and heart rate remained unchanged. In Protocol 2, overnight CPAP lowered nighttime systolic blood pressure (maximal change -23 +/- 5 versus placebo -1 +/- 7 mmHg; P=0.023) and was associated with lower nighttime diuresis (609 +/- 84 versus placebo 1004 +/- 160 mL; P=0.004) and improved morning orthostatic tolerance (AUC upright SBP 642 +/- 121 versus placebo 410 +/- 109 mmHg*min; P=0.014).CONCLUSIONS: CPAP is a novel nonpharmacologic approach to treat the supine hypertension of autonomic failure while improving nocturia and daytime OH.

Automated summary

We conducted two studies and found that continuous positive airway pressure (CPAP) can effectively reduce nocturnal supine hypertension in patients with autonomic failure, improve nocturia and symptoms of daytime orthostatic hypotension.