Fluctuation of skin lymphatic capillary pressure in controls and in patients with primary lymphedema.

The microlymphatic pressure was monitored by using the servo-nulling technique at the forefoot skin in 24 healthy volunteers (number of capillaries studied: 97) and in 27 patients with primary lymphedema (capillary number: 67). The lymphatic capillaries were stained by fluorescence microlymphography with fluorescein isothiocyanate-dextran 150 and cannulated using glass needles with a diameter between 7 and 9 microns. The lymphatic capillary hypertension described recently in primary lymphedema was confirmed in this series (mean pressure of controls 6.7 +/- 3.8 and, of patients 12.8 +/- 5.9 mm Hg; p < 0.001). Two patterns of pressure fluctuation were observed: rhythmic low-amplitude (mean value 3.7 mm Hg) waves with a frequency identical to respiration (respiratory movements of the thorax recorded simultaneously by a photo cell) and spontaneous nonrhythmic, low-frequency waves with a higher amplitude (mean value 5.5 mm Hg). The prevalence of waves synchronous with respiration was identical in patients and controls, whereas the low-frequency waves exhibited a significantly (p < 0.05) higher prevalence in the patients (41.7%) than in the controls (70.4%). The hypothesis is advanced that in primary lymphedema a considerable amount of lymphatic fluid is removed by lymphatic pathways with small calibre and high resistance, resulting in microvascular hypertension, and that contractions of the few preserved large proximal lymphatic collectors are enhanced. The latter mechanism could explain the increased prevalence of spontaneous microlymphatic pressure fluctuations with high amplitude and low frequency.