THURSDAY, Dec. 21 (HealthDay News) -- When patients are lying down, fluid displacement from the legs to the upper body significantly increases airflow resistance of the pharynx, which could lead to obstructive sleep apnea in those with heart or kidney failure, according to a study published in the Dec. 15 issue of the American Journal of Respiratory and Critical Care Medicine.
T. Douglas Bradley, M.D., of the Toronto General Hospital in Ontario, Canada, and colleagues studied 11 healthy, non-obese subjects as they lay on their backs. The researchers compared leg fluid volume, neck circumference and airflow resistance of the pharynx (Rph) before and after the subjects put on anti-shock trousers that increased their lower body positive pressure by 40 mm Hg.
The researchers found that the pressure application reduced leg fluid volume and increased neck circumference. They also found that displacement of just 12 ounces of fluid was enough to cause a 102 percent increase in Rph.
"Further studies will be required to determine whether fluid displacement from the lower to the upper body causes a greater increase in Rph in such patients than in subjects without these conditions, and whether fluid removal or displacement out of the neck in edematous patients reduces Rph," the authors write.
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