<p>The lymphatic system is a low-flow, low-pressure system, with the latter generally remaining in single figures, but occasionally rising to 40–50 mmHg when blocked. These low pressures – coupled with the delicate nature of even the collecting lymphatics, their location, and the relatively few muscular and structural elements in their walls – mean that the lymphatic system is very sensitive to external pressures, even more so than the venous system.</p>