Lymphatic Anatomy and Edema Physiology Flashcards
definition of lymphatic system
one-way system composed of tiny vessels which carry fluid from the interstitial fluid to the blood
functions of lymphatic system
- immune surveillance
- transport system
- edema prevention
immune surveillance
- Protects body from infection and disease via the immune response
- Production, maintenance and distribution of lymphocytes
transport system
Returns excess water, fats, proteinand large molecules to the venous
blood
edema prevention
Edemaresults when the lymphatic loadexceeds the lymphatic
transport capacity
what does edema do?
- impairs cellular nutrition (increases interstitial distance for oxygen and nutrients)
- impairs tissue viability
- increases risk for infection
- causes pain, mobility, and functional impairment
lymphatic levels of organization
*Initial lymphatics/lymphatic capillaries
*Pre-collectors
*Collectors
*Nodes
*Trunks
*Ducts
primary function of initial lymphatics/capillaries
absorb interstitial fluid from the interstitium
interstitial fluid =
lymphatic fluid
what does lymphatic fluid contain?
protein, water, fatty acids, salts, WBC, foreign debris, microorganisms
what are initial lymphatics/capillaries composed of?
*Composed of a single layer of epithelial cells
*No valvularstructure in the lumen
what do pre-collectors connect?
initial lymphatics to the lymphatic collectors
what aids transport in the pre-collectors?
- valvular structure and smooth muscle
do the pre-collectors absorb fluid?
not really –> minimal absorption of fluid
what do collectors do?
*Transport lymph to the lymph nodes and lymphatic trunks
*Contain contractilesmooth muscle
*Structurally similar to veins
*Contain valves that promote fluid proximally
lymphangion
region between the valves; considered the functional unit of the collectors
lymphangiomotoricity
- Frequency of lymphangion contraction
- Contracts 6-10 times per minute
- Increases 10 fold when there is an increased lymphatic load
the transport abilities of collectors are enhanced through:
- Respirations/diaphragmatic breathing
- Arterial/venous pulsations
- Skeletal muscle movement
- Newly formed lymphatic fluid
how many lymph nodes are in the human body?
600-700 nodes (regional or interval nodes)
can lymphatic vessels regenerate?
- yes (lymphangiogenesis)
- but lymphedema nodes cannot
functions of lymph nodes
- Removal of chemical, organic, inorganic cell products, viruses and bacteria
- Production of lymphocytes to support the immune system –introduce systemic immunity
- Passageway for lymphatic fluid
are lymph nodes normally palpable?
no
lymph nodes: practical anatomy
*Play an important role in the spread of cancer
*Regional lymph nodes my be invaded by malignant tumors which can result in metastases to other regions of the body
*Removal or irradiation of regional lymph nodes can result in lymphedema
L head and neck lymph nodes drain to
L cervical region
R head and neck lymph nodes drain to
R cervical region
L upper trunk drains to
L axilla
R upper trunk drains to
R axilla
L lower trunk quadrant drains to
L inguinal
R lower trunk quadrant drains to
R inguinal
what are the largest lymphatic vessels?
lymphatic trunks
what do lymphatic trunks form?
the main parts of the transporting vessels
what is the lymphatic trunks level?
Level at which the lymphatic fluid is mixed into the venous blood
via lymphovenous anastamoses
what innervates the lymphatic trunks
sympathetics
R lymphatic duct
- Drains R head, neck, trunk, arm
- Enters R internal jugular and subclavian veins
– right venous angle
left lymphatic duct (thoracic duct)
- Begins at the cisterna chyliat L2-T10
- Empties ~3L of lymph/day into L venous angle
- Drains lower half of body, L head, neck, trunk, arm
- Enters L internal jugular and subclavian veins
— Left venous angle
what are lympho-lymphatic anastomoses?
shared connections allowing drainage between two adjacent territories
why are lympho-lymphatic anastomoses a potential barrier to flow?
- Dilated avalvularcapillary network
- Shared connections are few but existent in the superficial collectors
what do lymph-lymphatic anastomoses include?
- Inter-axillary/Axillo-axillary
- Axillo-inguinal/Inguino-axillary
- Inter-inguinal/Inguino-inguinal
lymphatic watersheds
*Theoretical boundary between lymphatic territories
*Scarcity of lymphatic vessels
*Areas that are crossed by the lymphatic capillaries but not the deep collectors
what do lymphatic watersheds include
- Median sagittal
- Transverse
- Clavicular
- Spine of scapula
- chaps (“gluteal”)
microcirculation - diffusion
- Passive event
- Molecules move from higher to lower concentration, moving towards equilibrium
- Primary method of exchange of nutrients and metabolic end products across the capillary membrane
- Small molecules diffuse more rapidly
- Higher temperature –faster diffusion
Osmosis
- Unidirectional diffusion through a semi-permeable membrane to effect and equilibrium based on the concentration of protein molecules
Osmotic Pressure
Energy by which the more concentrated solution attracts water; the
lower the water concentration, the higher the osmotic pressure
hydrostatic pressure
Pressure exerted by fluid; blood pressure
what are colloids
protein molecules
colloidal osmosis
Semi-permeable membrane allows diffusion of water; prevents diffusion of protein molecules resulting in colloidal osmotic pressure
* Water molecules pas through the membrane increasing the pressure on the protein side
starlings law
*Rate and direction of fluid exchange between the capillaries and the interstitial space are determined by the hydrostatic and osmotic pressures of the two fluids
*Describes the balance of capillary filtration and capillary absorption
filtration
- Process by which fluid leaves the vessel
- Occurs when hydrostatic pressureforces water across a membrane
- Typically occurs at the arterial endwhere blood pressure is the highest
absorption
- Process by which fluid re-enters the vessel
- Result of osmosis
- Typically occurs at the venous end
what is blood capillary pressure
- Fluid pressure in the capillary at both the arteriole and venous ends
- Major determinant of fluid movement in normal circulation
what determines blood capillary pressure
- Determined by arterial pressure, venous pressure, pre-and post-capillary resistance
what is normal blood capillary pressure
- Normally around 35mmHg in the arteriole capillary which favors FILTRATION
- Normally around 15 mmHg in the venous capillary
what is blood capillary pressure practical application
Increases in venous capillary BCP with venous insufficiency will result in decreased absorption –> leading to edema
Interstitial pressure
- Fluid pressure in the interstitium
- Normally around 0-2 mmHg
- Minimal effect on filtration or absorption
plasma colloidal osmotic pressure
- Osmotic force due to plasma protein concentration
- Normally around 20-28 mmHg, which favors ABSORPTION in the venous end of the capillary
interstitial colloidal osmotic pressure
- Osmotic force due to interstitial fluid protein concentration
- normally around 3 mmHg
practical application of CPOi
COPi increases with lymphedema due to decreased uptake of proteins
in the lymphatic system, resulting in decreased absorption, leading to
edema
normal circulation results in
net filtration
what absorbs 90% of fluid and cells?
venous system
what absorbs 10% of fluid and cells?
- lymphatics (ultra filtrate)
- Ultrafiltrate includes large proteins and lipids that cannot be reabsorbed through the venous system
ultra filtrate =
Lymph obligatory load
- 2-4 L liquid, 80-200g protein per 24 hrs
key factors influencing lymphatic system
- lymphatic load
- transport capacity
- functional reserve
Lymphatic load
Amount of substances that have to be removed from the interstitium by the lymphatic system (water, proteins, fat, cells)
transport capacity
Maximum amount of lymph volume that can be transported by the lymphatics per unit of time
functional reserve
FR = TC - LL
lymphatic sufficiency
- LL < TC
healthy lymphatic system
dynamic insufficiency
LL > TC
healthy lymphatic system
low protein edema
(lymphatic load increases)
mechanical insufficiency
LL > TC
diseased lymphatic system = lymphedema
high protein edema
(transport capacity decreases)
combined insufficiency
LL > TC former healthy lymphatic system
LL > TC diseased lymphatic system
high protein edema
normal lymphatic compensations
*Increase of transport capacity
*Collateral circulation
*Lympho-lymphatic anastomoses
*Lympho-venous anastomoses
*Plasma protein reduction by macrophages
edema results when
lymphatic and venous systems can no longer absorb fluid
increased filtration, decreased absorption, or both
proteins that are not absorbed
will increase the interstitial osmotic pressure
long standing edema will change
from pitting edema to fibrosis due to the accumulation in the interstitial space
general edema (requires medical management)
- Congestive heart failure
- Renal failure
- Cirrhosis of the liver (salt and water retention)
- Nephroticsyndrome (low plasma oncotic pressure)
venous stasis (localized edema)
- Increased venous capillary hydrostatic pressure
- Resultant decrease in absorption
- Fluid accumulates in interstitial space = EDEMA
- Clinical picture: lower leg edema (unilateral/bilateral), hemosiderin staining
- Activates lymphatic functional reserve
- Longstanding edema will overwhelm lymphatic functional reserve => lymphedema
- Clinical picture: lower leg edema, fibrosis in tissues
how to treat venous stasis edema
compression
localized edema - inflammation
- Vasodilation of microcirculation leading to increased blood flow
- Increased capillary membrane permeability to fluid and proteins
- Net filtration of plasma into the interstitial space = EDEMA
- Chemotaxis through exit of leukocytes from venulesinto interstitial fluid; Phagocytosis to destroy bacteria; Tissue repair
- Clinical picture: edema localized to area of injury
from post surgical, trauma (strains, sprains)
how to treat inflammation
MLD and compression
localized edema - lymphedema
- Inability of lymphatic system to absorb lymph obligatory load
- Lymphatic load exceeds lymphatic transport capacity
- Increased interstitial osmotic pressure due to increase in interstitial proteins
- High protein fluid accumulates in interstitial space = EDEMA
- Clinical picture: edema may be unilateral or asymmetrical if bilateral; may involve whole extremity; history of lymphatic incapacity
how to treat lymphedema
treat with complete decongestive therapy
what is lymphedema?
*A swelling of a body part, most often found in the extremities
*An accumulation of protein-rich fluid in the interstitium which causes chronic inflammation and reactive fibrosis of the affected tissues
primary lymphedema
- Developmental abnormality of the lymphatic system
- Hereditary
- At birth
- < 35 years of age = lymphedema praecox
- > 35 years of age = lymphedema tarda
- Can often develop later in life without a cause
secondary edema
- Known cause of injury to lymphatic system
- Surgery and/or radiation
- Cancer
- Trauma
- Infection
- Filariasis
- Immobility
- Chronic venous insufficiency
- self induced
where can lymphedema develop
Only occurs in regions of body that affected lymph vessels and
nodes are responsible for draining
multiple classifications of primary lymphedema
- Onset time
- Clinical Manifestations
- Family History
- Lymphatic Malformation as seen in MR lymphangiography
filariasis treatment
*Global program to eliminate lymphatic filariasis
—– WHO sponsored
—– Mass drug administration of 2-drug treatment annually for 4-6 years
—— Ivermectinand Albendazole
*Hygiene to prevent infections
—– Infections increase fluid and decrease elastin in affected tissues
*Elevation, Exercise, Compression
characteristics of lymphedema
*Slow onset, progressive
*Pitting in the early stages
*Distal → Proximal
*Squaring of toes, (+)
Stemmer’s sign
*Dorsum of foot “Buffalo
hump”
*Loss of ankle contour
*Asymmetric (if bilateral)
*Cellulitis is common
*Rarely painful
*Discomfort common (heaviness, achiness)
*Hyperkeratosis, Papillomas, PeauD’Orange
*Ulcerations unusual
classification of lymphedema
slide 63
unilateral leg edema differential diagnosis
- Deep vein thrombosis
- Venous disease
- Arterial disease
- Lymphedema
- Trauma
- Surgery
- Obstruction of inguinal lymph nodes
bilateral leg edema differential diagnosis
- Cardiac disease
- Kidney disease
- Liver disease
- Immune/Nutritional/Endocrine disease
- Venous disease
- Lipedema
- Lymphedema
- Medications
- Obstruction of pelvic/abdominal lymph nodes
lipedema
*Found almost exclusively in females
*Bilateral accumulation of fat deposition in the LE and buttocks
*Insidious onset in adolescence
*Progressive swelling of the lower extremities; sparing of the feet; non-pitting
*Painful, varicose veins, weight gain
why is early diagnosis of lipedema important
to prevent impaired mobility, arthritis, and lymphatic insufficiency
lipedema treatment
- Weight control
- Complete Decongestive Therapy
- Liposuction
- Outcomes –improvement in pain, sensitivity to pressure, swelling, bruising and functional mobility
what is lymphangitis
*Infection of the lymphatic vessels
* Potential pathogens: bacteria, mycobacteria, fungi, parasites
signs and symptoms of lymphangitis
- Fever and chills
- Swollen lymph nodes
- Malaise
- Loss of appetite
- Headache
*aching muscles
cellulitis
- Common but potentially serious bacterial skin infection
- Infection can spread through lymphatic system into blood stream –> life threatening if untreated
signs and symptoms of cellulitis
- Erythema
- Edema
- Pain and tenderness
- Warmth
- Fever
- Skin dimpling
- blisters
what is obesity associated with?
sleep apnea and venous insufficiency
FACT-B +4
- Functional Assessment of Cancer Therapy –Breast
- Consists of 36 items across 5 domains
- Physical well-being, social/family well-being, emotional well-being, functional well-being and arm morbidity (4 questions on swelling and tenderness)
DASH
- Disability of Arm, Shoulder and Hand Questionnaire
- 30-item self report evaluating patient symptoms and functional tasks associated with limitations of the arm, shoulder and hand
Perometry
*Optoelectric device utilizing infrared light to create a 3D silhouette of the limb
*Can detect changes of less than 150 ml in a limb
Bioimpedance: ImpediMed
L-Dex® U400 is a bioimpedance analyzer designed to assist in the clinical assessment of extracellular fluid differences in the arm
volumetric girth
Volume = h . ((Ct . Ct) + (Ct . Cb) + (Cb . Cb)) / (12 . Π)
Interraterand intraraterreliability = .91-.99 (ICC 2,1)
Standard Error of Measurement = 116 mL
water displacement
- Water volume considered “gold standard”
- Provides an accurate way to include volumetric data of the foot and hand in the total limb volume measurement
- Cannot be performed with open wounds
- Time consuming and cumbersome
