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81 Cards in this Set
- Front
- Back
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2 functions of the lymphatic system
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1. Immune - production, maintenance, distribution of lymphocytes
2. Faciliatete fluid movt from tissues back to BS to maintain normal blood volume and eliminate chemical imbalances in the interstitial fluid |
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What is ultrafilatration and resabsoprtion and where do they occur?
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Ultrafiltration occurs on the arterial end of the capillaries and results in fluid being pushed out into the tissues
Reabsorption occurs on the venous end of the capillaries are results in oxygen poor fluid returning to the BS when the tissue hydrostatic pressure is high enough |
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What can lymphatic vessels carry that venous vessels cannot?
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Protein-filled fluids
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3 general functions of lymphathic circulation?
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1. Recyle - remove excess fluid and proteins from tissue to return to BS
2. Garbage collection - removes waste products from tissues 3. Alarm system - carries antigens to lymph nodes to alert immune system |
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Why do we now think that is it the lymphatic system (and not venous sytem) that takes up the majority of excess tissue fluid?
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B/c venous insufficiency doesn't produce much swelling when lymphatic system is still in tact
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4 components of Microcirculation
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Capillaries
Tissue channels Proteolytic cells (macrophages) Initial lymphatics |
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What are capillaries composed of?
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Single layer of endothelial cells with a basement membrane joined in tight or narrow junctions
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How can proteins move across capillaries?
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Slowly via vesicles, which make up 35% of the endothelia
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Sol vs. gel state of Tissues
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Sol state consists of moving fluid through tissues
Gel state consists of collagen, elastin fibers, ground substance (hyaluranon and other PGs) which are holding onto some structure |
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What are tissue channels?
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Space where fluid can move thru tissues
Form a continuous network of passageways t/o the body Drain into initial lymphatics at very short distances (10-50 microns) Act as pre-lymphatics in regions where there are no lymph vessels (retina and brain) |
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What is hydrostatic pressure like in more tissue channels?
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Usually THP is negative (-3 to -5 mm HG), but is high at encapsulated organs and during edema
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Hydrostatic pressure vs. Colloidal Osmotic Pressure (COP)
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Hydrostatic - forces water out of a solution
COP - Osmosis - forces water into a solution ie. forcing protein molecules to draw fluid in to area of lesser concentration |
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What is total tissue pressure (TTP) the sum of and what is it influenced by?
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Sum of sol and gel pressure
Skin stretch, massage, movt, ex, respiration, peristalsis, increased fluid in tissues, compression |
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How can proteolytic cells (macrophages) help fluid move more easily thru the cannels to be returned to the ciculatory system?
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Through proteolysis, b/c they will break down proteins, which decreases the solute level
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Location of Macrophages
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Originate in bone marrow
Travel in blood as monocytes Some lodge in lymph nodes Majority found in interstitial fluid |
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Fxt of macrophages
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1. Lyse proteins and other waste debris
2. store particles that cannot be broken down 3. carry antigens to lymph nodes to alert immune cells 4. help destroy antigens` |
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How can lymphadema cause CT fibrosis?
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Conc'd proteins in the interstitial fluid act as foreign bodies stimulating chronic inflammation and proliferation of CT. The continual progression of fibrosclerotic tissue causes a reduction in the transport capacity of the entire remaining system.
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What can happen if lymphadema is left untreated?
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Proteins and cellular debri continue to accumulate, fibrosclerotic tissue continues to accumulate, and a cycle of inflammation, infection, and limb elargement with begin
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Where are initial lymphatics located?
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Just under the skin in the subcutaneous tissue near capillaries
They form a mesh and have small finger like projections |
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How are initial lymphatics similar and different from venous ends of capillaries?
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Resemble venous end of caps by having a single layer or endothelial cells
Different in that they have loose, openable junctions made of overlapping endothelial cells |
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Job of microfibrils that are attached to the initial lymphatics?
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Connect the endothelial cells of the initial lymphatics to the elastin in the CT of the skin (This is how lymph massage can work to open the valves)
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3 types of lymphatic vessels
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Superficial (initial lymphatics)
Intermediate (pre-collectors) Deep |
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How do gas and lipid substances get through membrane?
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Dissolve and diffuse
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How does water get through membrane?
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Diffuse thru walls, leave via small pores, close intercellular junctions, fenestrae, and open junctions
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How do ions and small molecules get through membrane?
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Thru close intercellular junctions, fennestrae, and vesicles
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How do larget molecules get through membrane?
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Fenestrae and open junctions
Moved by bulk flow Main avenue is vesicles |
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What is large molecules permeability affected by?
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Molecular sieving : pore size (reflecion, blocking pores, wall friction) and electrical charge
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What is Starling's Forces a shoving match between?
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Pressure pushing fluid away (hydrostatic pressure) and Pressure pulling fluid in (Colloidal osmotic pressure)
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2 modifiers of permeability for proteins
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1. Filtration permeability coefficient: Kf... more permeable = larger coefficient
2. Reflection coefficient: 0-1, at 1, no pores exist and protein molectules can't get out. At 0, all proteins can get out. AVG value = 0.7 |
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Starling's Equation for net fluid flow?
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Kf (BHP-THP) - reflection coeff (BCOP-TCOP)
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Formula for effective ultrafiltration rate
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(BHP - THP) which occurs at arterial end of capillary
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formula for effective reabsoprtion rate
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(BCOP - TCOP) Which occurs at venous end of capillary
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What must lymph equal to maintain equlibrium?
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Net fluid flow - Startling's equation
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How do the flaps open to allow fluid into the lymphatics?
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As interstitial fluid inc and tissue pressure inc, the stretched anchoring filaments will pull on the endothelial cells resulting in an open junction btw the cells
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What are the bigger lymph collectors similar to?
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BVs with intima (inner wall), media (medium layer), and adventia (outer wall)
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Where do mamillary glands drain their lymph to?
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Axillary nodes, also parasternal and supraclavicular lymph nodes
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What could metasates in the axillary or supraclavicular lymph nodes result in?
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BC damage - parese of UEs
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Where do teh axillary lymph nodes receive lymph from?
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UE and skin of thorax (ANT and POS) above the horz watershed (belly button)
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What areas drain into the inguinal lymph nodes?
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Abdominal, lumbar, gluteal areas, external genitalia, and LEs
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Where may lymphadema occur after radiation to Andrew's breasts?
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drainage of lymph from UE will be impaired b/c of the axillary nodes
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What parts of the body drain into the thoracic duct? Right lymphatic duct?
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TD - L UQ and B LQ
RLD - R UQ |
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Where are the inguinal lymph nodes located?
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Medial femoral triangle - inguinal lig, sartorius and gracilis border it.
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How can lymphadema of the LEs occur?
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Most commonly due to congenital malformation of if lymphatic system
Can also occur due to dissection of inguinal lymph nodes |
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What is Lymph Time Volume?
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The amt of lymphatic loads transported by the lymphatic system in a unit of time (ie. TD: 2 L in 24 hrs)
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What is Transport Capacity?
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Equal to the maximum Lymph Time Volume (what the healthy lymphatic system can transport when working at max capacity). This is plenty of room for the healthy lymph system to response to whateva
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Lymphatic Safety Factor
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The fact that the Transport Capacity is much higher than the nomal lymphatic load and can respond to an increase in lymph no problem
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Dynamic (High Volume) Insufficiency
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When the lympatic load exceeds the Transport Capacity of the healthy lymphtic system, fluid will accumulate in the interstitial fluid. (Manual lymph techniques not recommended)
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Interventions for Dynamic (High volume) insufficiency?
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Eelvation, ex, compression garments if indicated
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What is Mechanical (Low Volume) Insufficiency?
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The lymphatic system is dx and has a reduced Transport Capacity - not able to cope with nomral lymph load. Safety factor is shot
Caused by trauma, surgery, infection, valvular insufficiencies, malofrotmations of the lymph system. This causes lymphadema |
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What is Safety Valve Insufficiency?
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Lymph load is inc and at the same time Transport Capacity is dec. Already have a problem, managed well, and then something happens (ie. infection) and you get blown up
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Examples of primary lymphadema
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Aplasia, hypoplasia, hyperplasia
Fibrosis or agenesis of lymph nodes |
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Examples of secondary lymphadema
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Lymph node dissection
Radiation Post-trauma Self-induced Malignancies |
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4 stages of lymphdema
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1. Latency (reduced Transport Capacity but no physical evidence)
2. Stage I (Pitting edema, no secondary tissue changes, elevation reduces swelling) 3. Stage II (Fibrosclerotic changes, hardening of tissue, and frequent infections) 4. Stage III (Extreme increase in volume and texture) |
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Why are infections common in lymphedema?
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Protein offer perfect env for bacterial growhth
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S/s of malignant lymphedema?
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Sudden onset
Rapid progression Pain Paresthesia Skin changes Dilated superficial veins |
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S/s of benign lymphedema?
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Unilateral (if bilateral, then swelling is asymetrical)
Slow progresion Normal skin color Positive Stemmer sign No pain or paralysis |
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General tx for lympedema?
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MLD
Short stretch bandages Skin care Remedial exercises Pt instruction |
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Components of Complete Decongestive Therapy
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MLD
Compression bandaging Decongestive ex (mm pumps) Skin care |
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2 phase therapy of lymphedema?
Overall goal? |
Phase I (Intensive): Mobilize accumulated protein rich fluid and initiate reduction of fibrosclerotic tissue
Phase II: Preserve and improve success achieve in Phase I Bring dx back to latency stage |
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Goals of Lymphedema Tx
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1. Utilize remaining and intact lymph vessels
2. decongest swollen body part 3. eliminate fibrotic tissue 4. avoid re-accumulation of lymph fluid 5. prevent/eliminate infections (skin care) 6. Maintain a near normal limb size |
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Pneumatic compression pumps
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Negative effects b/c cuases extreme fibrosis in ipsilateral quadrants, formation of cysts and fistulas, and swelling of genitalia b/c pump pushes fluid to the shitty nodes
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Charles procedure or debulking procedure
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Leaves unpleasant results bc dangerous and side effects
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When are elastic support garments effective?
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If prescribed after extremity is decongested.. or else it owuld just push fluid out - not protein. Fluid would rush right back in after pressure garments were released
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Diuretics for lymphadema?
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Don't do it - pulls water out but not protein. Will likely take fluid from other areas of the body
Sometimes necessary in malignant lmphedema |
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Why short stretch bandages?
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Have a high working pressure and low resting pressure, meaning pressure will maintain during activity
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Pathophysiology of fibrossi
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Conc'd proteins act as foreign bodies and cause chronic inflammation and proliferation of CT
Metabolic changes (reduced lymph flow) also causes accumulation of fibrosclerotic tissues |
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What happens to macrophages once you develop lymphadema?
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They become ineffective
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Two types of drug therapies for lymphadema
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Benzopyrones (flavenoids and coumarin)
Herbal: licorice root |
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What are Beonzopyrones?
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Falvenoids and Coumarin
Stimulate macrophage activity Not approved in US b/c chance for liver adverse effects and takes 6 months to see results Names include Venalot, Paroven, Venoruton |
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Why is licorice root not used much to tx lymphadema?
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Adverse liver effects
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6 type of measurements for lymphadema
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Girths
Volumeter Tonometer Weight Calipers Photos |
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Swelling severity scale
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0-5% = minimal inc volume
6-20% = mild incr volume 21-40% = moderate inc volume 41-60% = marked >60% = severe |
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% for low, medium and high stretch bandages
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Low = up to 90%
Med = 90-140% High = >140 % |
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Compression classes - class I vs. IV
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I: 20-30 mmHg
IV: >50 mmHG (Ted hoses = 8-10 mmHg) |
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What are foams useful for?
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Breaking up fibrosis
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Gradient compression
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More layers distally
Spirals or Herring bone Overlap more distally, less proximally BUT should always have at least 50% overlap Start 1st distal bandage with several anchoring loops |
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GRADING SYSTEM
#1+ |
(numerous small clumps-very cloudy background)
numerous medium and small sized agglutinations. background is turbid with many free red cells |
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fluid moves THRU tissue channels under control/influence of...
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tissue hydrostatic pressure
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fluid moves OUT of tissue channels under control/influence of...
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TTP and COP
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2 fluid exchange mechanisms
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permeability and pressures
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microfibrils attach on one end to ____ and at the other end to _____
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endothelial cells
elastin in CT |
