| "Puffy-Head Bird-Legs" Syndrome |
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"Puffy-Head Bird-Legs" syndrome, as its name suggests, occurs when sinuses swell and blood shifts away from the legs, causing the respective appearances. This is a direct result of microgravity. To accommodate for this shift in fluid, more urine is excreted to decrease excess fluid. After a few days, symptoms are less severe, and after returning to earth, gravity causes fluid levels to return to normal in a couple of days.
On Earth, the force of gravity causes blood to gather in the veins of the legs, away from the chest and head. In microgravity, this blood accumulates in the upper limbs. The result is a “puffy head” as the face and sinuses swell, and “bird legs” due to weakened muscles and the shift of blood away from the legs. Muscles weaken from lack of use in supporting body weight, but proper exercise can help prevent this.
When blood shifts to the chest, the heart increases blood flow by pumping more blood per beat. This increase causes the pituitary gland to decrease secretion of anti-diuretic hormone (ADH), which in turn expands blood vessels, and increases excretion of urine by the kidneys. This helps rid the chest and head of the excess fluid.
In a few days, the body's fluid levels are less than what they were on Earth. The symptoms become less severe, and upon returning to Earth, gravity will reverse the effects. As the astronaut takes in more water, his fluid levels will return to normal in a couple of days.
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