Mechanical stimulation of the lymphatic system
Interstitial fluid dynamics and lymphatic flow are known to be both temperature and exercise dependent which has been attributed to filtration forces acting across capillary walls (38). Tissue compression [e.g. when walking] increases interstitial flow whereas stretching impedes this in a process that may be governed by fibroblasts (39). The impact of these mechanical phenomena on SQ drug dispersion and uptake has not been extensively studied though models have been developed (40). In an effort to promote lymphatic flow [and thus drug uptake] it is also possible to employ other mechanical methods. Clinical studies have been conducted on the impact of manual lymph drainage (MLD) in fibromyalgia patients (41). The methods, which include use of soft tissue massage regimens, targeted physical exercise [e.g. yoga], use of graduated compression bandages and pneumatic devices (e.g. the Lympha Press system) have shown a dramatic increase in lymph flow, reducing edema and other clinical markers (Figure 3) (42). Studies have also shown synergistic impact of ultrasound with manual drainage to increase lymph flow (43), which may afford additional benefits. The connective tissues are not fully hydrated at physiological state, and compression/stretching cycles results in substantial flux as GAG’s attract water based on their net negative charges.