The Vicious Cycle

the-vicious-cycle-01

There is increasing information available on the effects of lymphatic dysfunction and the relationship between these outcomes. Before we explore these effects it’s important to revisit what are the mechanisms of normal lymphatic pumping and some useful reminders.

The article titled: Lymphatic pumping: mechanics, mechanisms and malfunction Scallan, Zawieja, Castrorena-Gonzalez and Davis. 2016. Journal of Physiology provides a detailed description of the physiology of lymphatic pumping. The key points are:

  • Initial capillaries have an absorptive role, collectors transport lymph and lymph nodes/lymphoid organs assist immune responses.
  • Movement of lymph is via a combination of extrinsic (passive) and intrinsic (active) forces.
  • “1/3 of lymph transport in the lower extremities results from compression of skeletal muscle contraction (extrinsic pump) and 2/3 to active pumping (intrinsic pump) of the collecting vessel network”.
  • “Robust contractions of lymphatic cells are the driving force for the active lymph propulsion against adverse gradients.”
  • Backflow is limited by one way valves.
  • Contraction waves of lymphatic vessels need to be coordinated along the length of the lymphangion.
  • There is regulation of lymphatic pumping by lymphatic preload, afterload and spontaneous contraction rate, contractility and neural influences.
  • A relatively new concept is that lymphatic collectors are permeable to solute and fluid and their albumin permeability is similar to postcapillary venules. This permeability allows antigens, transported via the collectors, to reach local immune cells to assist immune responses.

This article and another by Liao and von-der Weid (Angiogenesis, 2014; 17 (2) p 325 -334) provide a detailed explanation of what happens when lymphatic dysfunction occurs. In a nutshell:

  • Vessels are enlarged, exhibit weak contractions and elevated diastolic pressures with limbs in a dependent position.
  • It is still unclear whether lymphatic pump dysfunction precedes lymphoedema or lymphoedema overloads the capacity of the lymphatics to precipitate contractile dysfunction.
  • Lymphatic contractile dysfunction is often associated with tissue inflammation. Inflammation produces nitric oxide which inhibits lymphatic contraction.
  • Chronic inflammation produces fibrosis which is a significant factor in the aetiology of fat production.

For lymphoedema practitioners the molecular biology of this topic can sometimes be difficult to put in way that our clients can understand.

The Canadian Lymphoedema Pathways publication has an excellent article “Studying inflammation-induced lymphatic dysfunction to better understand lymphedema by Dr Pierre-Yves von der Weid. 2016

Read the article in full

This article will assist you educating your clients on this topic.

The key messages are:

1. Lymphatic pumping is influenced by:

  • The volume of lymph to be drained. An increase in lymph results in an increase in pumping. Except when there is inflammation.
  • Chemical activity.
  • Inflammation.

2. Lymphatic pumping is the main way to move lymph and in some areas the only way.

3. Inflammation:

  • Accompanies lymph stasis and oedema which causes tissue fibrosis and fat accumulation over time.
  • Dilates the lymphatic vessels and then the valves don’t work properly.
  • Inflammation decreases the contraction frequency of lymphatic collectors and results in a decrease in lymph flow with resulting increase in swelling. The take home message for clients is that during inflammation the lymphatic drainage from the limb will be reduced.

4. “Inflammation, fat deposition and lymphatic dysfunction/lymph stasis occur as a consequence of each other in a vicious circle manner” They each exacerbate each other.

Taking all of this information into consideration, below is a diagram that you might find client friendly and make the take home message that decreasing the swelling ( or reducing the risk of swelling) is important if you want to avoid long term problems. It includes the pathways that you will most commonly discuss with your clients.

road-map-002

Download a poster version