Interstitial fluid colloid osmotic and hydrostatic pressures in subcutaneous tissue of patients with nephrotic syndrome

Abstract

Colloid osmotic pressure in plasma (II_p) and in interstitial fluid from subcutaneous tissue (II_i) was measured in 13 patients with nephrotic syndrome and in 20 healthy volunteers. Interstitial fluid was sampled by nylon wicks, and interstitial fluid pressure was measured by the ‘wick-in-needle’ technique. In the persons with normal plasma proteins we found a mean II_p of 26.9 mmHg, a mean II_i of 15.8 mmHg on the thorax, and a mean II_i of 11.1 mmHg on the lower leg. A fall of II_p from normal values to 16.5 mmHg caused a fall in II_i of about 8 mmHg on the thorax and about 7 mmHg on the leg without oedema formation. In patients with II_p from 16.0 mmHg down to 8.0 mmHg, II_i did not change very much, and was about 5.5 mmHg on the thorax and 2.6 mmHg on the leg. These results support the view that reduction of II_i plays an important role as an oedema preventing factor in patients with hypoproteinaemia.

Key-words:

• oedema-preventing mechanisms
• colloid osmotic pressure
• interstitial fluid
• wick method
• skin
• capillary
• albumin
• hypoproteinaemia
• tissue pressure