Lymphatic capillary pressure in patients with primary lymphedema.

Flow and pressure dynamics in minute human lymphatics are unexplored. Lymphatic capillary pressure was measured by the servo-nulling technique at the foot dorsum of 14 patients with primary lymphedema and 15 healthy controls. Glass micropipettes (7-9 microns) were inserted under microscopic control into lymphatic microvessels previously stained by fluorescence microlymphography (FITC-Dextran 150,000). Mean lymphatic capillary pressure was 7.9 +/- 3.4 mm Hg in the controls and 15.0 +/- 5.1 mm Hg in the patients. The difference was significant at the P < 0.001 level. In about half of the patients and control subjects studied pressure fluctuated by more than 3 mm Hg. The mean intralymphatic pressure of lymphedema patients was slightly below mean interstitial pressure measured by J. T. Christensen, N. J. Shaw, M. M. Hamas and H. K. Al Hassan (1985, Microcirc., Endothelium, Lymphatics 2, 267-384) (17.9 mm Hg) in lower leg lymphedema. Microlymphatic hypertension present in patients with primary lymphedema is probably an important factor for edema formation.