title: Plasma colloid osmotic pressure in venous blood from the human foot in orthostasis.
abstract: Several theories could explain the slow rate of edema formation in the feet of sitting or standing man. One possible mechanism is a rise in local plasma colloid osmotic pressure (pi p). We measured pi p in blood from superficial veins of warm and cold feet during orthostasis. The difference in venous pi p between the foot and the arm averaged 12.8 mmHg (range 9.4-16.1 mmHg) in subjects sitting in a cold room. Hemoconcentration was also reflected as increased hematocrit. These findings support the view that a local increase of pi p in foot capillaries contributes considerably to edema prevention during orthostasis.
mesh_terms: D000328:Adult; D005528:Foot / Q000098:blood supply*; D006400:Hematocrit; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D008297:Male; D008875:Middle Aged; D009997:Osmotic Pressure; D011187:Posture; D013696:Temperature; D014690:Venous Pressure
chemical_list: D006454:Hemoglobins