Wearing compression stockings may be a simple low-tech way to improve obstructive sleep apnea in patients with chronic venous insufficiency (CVI), according to researchers.
"We found that in patients with chronic venous insufficiency, compression stockings reduced daytime fluid accumulation in the legs, which in turn reduced the amount of fluid flowing into the neck at night, thereby reducing the number of apneas and hypopnea by more than a third," said Stefania Redolfi, MD, of the University of Brescia in Italy, who led the research.
CVI occurs when a patient’s veins cannot pump enough oxygen-depleted blood back to the heart. It occurs most often in the veins of the legs.
The findings appear online ahead of publication of the American Thoracic Society’s American Journal of Respiratory and Critical Care Medicine.
In active people, fluid accumulation in the legs is counteracted by leg muscle contractions that squeeze the veins. However, prolonged sitting can prevent this process, and the accumulated fluid in the legs then shifts rostrally overnight. This shift results in fluid accumulation in neck tissue and is thought to increase apneic events by increasing the volume of the tissue, leading to repetitive collapse of the pharynx during night breathing. In otherwise healthy subjects who have heart failure or hypertension, the amount of this overnight rostral fluid shift is strongly correlated with the degree of overnight increase in neck circumference and the number of apneas and hypopneas per hour of sleep.
To investigate whether compression stockings could alleviate this problem, the researchers recruited subjects from the chronic venous insufficiency clinic at La Pitié-Salpêtrière hospital in Paris. Twelve patients were randomly assigned to 1 week of wearing the compression stockings or to a 1-week control period without compression stockings. At the end of the first week, they crossed over to the other arm of the study. Each subject underwent polysomnography and overnight changes in leg fluid volume and neck circumference were measured at baseline and at the end of the compression stocking and control periods.
At the end of the compression stocking period, subjects had an average of a 62% reduction in overnight leg fluid volume change as compared to when they did not wear the stockings. Patients also had a 60% reduction in neck circumference increase, which the researchers used as a proxy measurement to estimate fluid shift into the neck and a 36% reduction in the number of apneas and hypopneas per hour of sleep.
"Our findings provide proof-of-concept that among subjects with CVI, overnight rostral fluid displacement is a mechanism of disease for OSA. The effect of compression stockings on OSA is based on counteracting this fluid displacement. Prevention of dependent fluid accumulation could constitute a new therapeutic approach to OSA," said Redolfi.