Fluid & swelling in legs/ankles/feet during day was reduced (average 1.32 lbs, or 62%), as was its redistribution into the neck at night.
Wearing compression stockings may be a simple low-tech way to improve obstructive sleep apnea in patients with chronic venous insufficiency, according to French 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,” says lead researcher Stefania Redolfi, MD, at the University of Brescia in Italy.
The Mechanism Involved
Chronic venous insufficiency (CVI), marked most often by foot/ankle/leg swelling, occurs when a patient’s veins cannot pump enough oxygen-depleted blood back to the heart. In active people, accumulation of fluid in the legs is counteracted by leg muscle contractions that squeeze the veins. However, prolonged sitting/inactivity can prevent this process.
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 hypopnea per hour of sleep, the research team found. [See their report, “Attenuation of Obstructive Sleep Apnea in Subjects with Venous Insufficiency,” published online Aug 4 by the Journal of Respiratory and Critical Care Medicine.]
Sought Alternatives to CPAP
Continuous positive airway pressure machines, known as CPAP, are one of the only treatment options currently recommended for people with OSA. However, many find wearing a mask all night prohibitively uncomfortable, and compliance is low, resulting in many patients living with untreated OSA and its serious health consequences.
Finding a more effective means of treating OSA, therefore, is a high priority, and Dr. Redolfi and colleagues sought to determine whether a simple intervention like wearing compression stockings might be effective in some OSA patients.
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“We hypothesized that the fluid accumulation that occurs in the legs of people with chronic venous insufficiency would be reduced by wearing compression stockings, and that the reduction in the fluid would also reduce the shift of that fluid to the neck during the night,” says Dr. Redolfi. “There is strong evidence linking that rostral shift of fluid overnight to apnea. If we could reduce that, we would expect that apneic events would likewise be reduced.”
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 one week of wearing the compression stockings or to a one-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 stockings and control periods.
Average 36% Apnea Reduction In 7 Days
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 hypopnea 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 obstructive sleep apnea,” Dr. Redolfi says. “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.”.
Will Longer Use Improve Benefits?
“These findings are what we expected,” she continued, “but the extent to which simply wearing compression stockings reduced apnea in just one week was not expected. It would be very interesting to see whether the wearing of the stockings over longer periods would have an even greater effect.”
Source: American Thoracic Society news release, Aug 4, 2011