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Edema
Edema
Edema is defined as an increase in
the extravascular (interstitial)
component of the extracellular fluid
volume, which may expand by
several liters before the
abnormality is recognized.
Edema
The blood volume that is detected by the
volume sensors located in the arterial side of
the circulation is sometimes referred to as the
effective arterial blood volume (EABV).
EABV is the amount of arterial blood volume
required to adequately ‘fill’ the capacity of
arterial circulation.
ECF volume and EABV can be independent of
each other.
Edema
For example, some edematous states can
be associated with an increase in total
ECF volume and decreased EABV.
Also, postural changes may cause fluid
shifts that influence the EABV without
affecting the total blood volume.
Volume changes in various
disease states
Renal
Compartment Volume Nephrosis Congestive A-V fistule
with congestive artery
depletion
heart
failure
state
stenosis
Total ECF
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volume
Total blood
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↑
volume
Arterial blood
↓
↓
↓
↑
↑
volume
EABV
↓
↓
↓
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↑
Renal blood
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↓
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flow
Edema
The characteristic feature of the body
fluid homeostatic mechanism is that the
composition of the body fluid
compartments remains remarkably
constant despite wide daily variations in
solute and water intake.
Edema
The integrated homeostatic response
involves two key components:
an afferent limb that contains sensors that
detect changes in the effective circulating
volume and
an efferent limb that regulates the rate of
sodium excretion by the kidney
Major efferent mechanisms
regulating ECF volume
I. Glomerular filtration rate
II. Physical factors: at the level of the proximal
tubule beyond the proximal tubule
III. Humoral effector mechanisms
Renin-angiotensin-aldosteron system,
Vasopressin, Catecholamines, Prostaglandins,
Kinin-kalikrein system, Atrial natriuretic
peptide, Endothelium-derived factors
IV. Renal sympathetic nerves
Hormones regulating renal sodium
excretion – Vasoconstrictors
Mediators
Angiotensin II
Site of production
Circulating/local
generation
Site of action
Glomerular arterioles,
proximal tubule
Tubular actions
Na retention
Aldosterone
Vasopressin
Adrenal glands,
Hypothalamus
Na retention
Water retention
Na retention
Catecholamines
Adrenal glands
Distal tubule
Thick ascending limb
of loop of Henle (TAL),
distal tubule
Glomerular arterioles,
proximal tubule
Glomerular arterioles,
proximal tubule
Glomerular arterioles
Inner medullary
collecting duct (IMCD)
Tubular Na/K ATPase
Kidneys
Renal sympathetics
Endothelium
Endothelin 1
Adrenal glands
Na/K ATPase
inhibitors
Na retention
Na retention
Natriuresis
Natriuresis
Hormones regulating renal sodium
excretion – Vasodilators
Mediators
Atrial natriuretic
peptide
Brain natriuretic
prptide
C-type natriuretic
peptide
Urodilatin
Nitric oxide
Site of production
Cardiac atria
Tubular actions
Natriuresis
Brain
Site of action
Cortical collectin
duct(CCD)
CCD/IMCD
Endothelium
CCD/IMCD
Natriuresis
Renal tubules
Endithelium
CCD/IMCD
Glomerular arterioles,
distal nephron
Glomerular arterioles,
TAL, CCD, IMCD
Glomerular arterioles,
IMCD
Natriuresis
Natriuresis
Prostaglandins E2 and
I2
Bradykinine-kalikrein
Kidneys
Distal nephron
Natriuresis
Natriuresis
Natriuresis
Classification of disorders associated with
extracellular fluid volume excess on the
type of physiologic derangement
I. Disturbed Starling forces: reduced effective
circulating volume, edema formation
-Systemic venous pressure increases: right
heart failure, constrictive pericarditis
-Local venous pressure increases: left heart
failure, vena cava obstruction, portal vein
obstruction
-Reduced oncotic pressure: nephrotic
syndrome
-Combined disorders: cirrhosis
Classification of disorders associated with
extracellular fluid volume excess on the
type of physiologic derangement.
II. Primary hormones excess: increased effective
circulating volume
Primary aldosteronism
Cushing’s syndrome
Syndrome of inappropriate secretion of
vasopressin (SIADH)
III. Primary renal sodium retention: increased
effective circulating volume
Acute glomerulonephritis
Edema
Depending on its cause and mechanism,
edema may be localized or have a
generalized distribution;
it is recognized in its generalized form by
puffiness of the face, which is most readily
apparent in the periorbital areas, and by
the persistence of an indentation of the skin
following pressure; this is known as
"pitting" edema.
Edema
Therefore, the weight gain of
several kilogrames usually precedes
overt manifestations of edema, and
a similar weight loss from diuresis
can be induced in a slightly
edematous patient before „dry
weight” is achieved.
Edema
In its more subtle form, it may be
detected by noting that after the
stethoscope is removed from the
chest wall, the rim of the bell leaves
an indentation on the skin of the
chest for a few minutes.
Edema
An early symptom a patient may
note is the ring on the finger fitting
more snugly than in the past, or
difficulty in putting on shoes,
particularly in the evening
Ascites and hydrothorax refer to
accumulation of excess fluid in the
peritoneal and pleural cavities,
respectivly, and are considered to
be special forms of edema.
Anasarca refers to gross,
generalized edema.
Congestive heart failure
Clinical manifestation
Patient with congestive heart failure
usually present with history of
dyspnea on exertion,
weakness,
decrease exercise tolerance,
orthopnea,
paroxysmal nocturnal dyspnea,
sometimes nocturia
Patient with congestive heart
failure
Physical examination reveals
increased weight gain
distention of the jugular veins
pulmonary rales
tachycardia, third heart sound
ankle edema (pretibial and ankle edema is
frequently seen in the evening in
ambulatory patients, and presacral edema
is features of individuals at bed rest)
Nephrotic syndrome
The edema of nephrotic syndrome is
usually diffuse and manifests itself as
anasarca.
Periorbital edema is a characteristics
feature of nephrotic syndrome.
Some patients may present with pleural
effusions or ascites.
SODIUM HOMEOSTASIS AND
EDEMA FORMATION
The presence and severity of edema are related in a general way
to the extent of depression of albumin concentration; however,
notable exceptions may occur.
Initially a drop in interstitial oncotic pressure concomitant with
the decline in plasma oncotic pressure tends to preserve the
transcapillary oncotic pressure gradient and retard the
development of edema.
The limited ability of the interstitial oncotic pressure to fall
further despite worsening of plasma albumin concentration and
plasma oncotic pressure (below about 8 mm Hg) ultimately leads
to enhanced flow of fluid into the interstitial space at rates that
cannot be accommodated by a further increase in lymphatic
flow, so edema fluid accumulates.
SODIUM HOMEOSTASIS AND
EDEMA FORMATION
It seems likely that the Na+ retention in nephrotic
states is related to intrarenal events and is not
dependent on a change in activity of the reninangiotensin-aldosterone system.
Indeed, values for plasma volume, plasma renin,
and plasma aldosterone are highly variable in
nephrotic subjects with edema.
In general, expanded plasma volume and
suppressed plasma renin are more often observed
in patients with proliferative glomerular lesions,
especially with reduced GFR.
SODIUM HOMEOSTASIS AND
EDEMA FORMATION
Lowered plasma volume and enhanced plasma renin are
more often observed in patients with minimal glomerular
lesions and the acute onset of severe proteinuria.
Water immersion of nephrotic subjects with edema will
result in a diuresis, natriuresis (albeit blunted compared
with normal subjects), phosphaturia, and calciuria.
These effects can occur without major change in plasma
aldosterone concentration, and the intensity of the
augmented excretion of Na+ is related directly to the
preimmersion plasma volume.
Complications and General Management
EDEMA
The edema of nephrotic syndrome is in many instances a
bothersome but not debilitating clinical feature, but it can
occasionally be severe and associated with accumulation of
peritoneal or pleural fluid.
Pericardial effusions are rare in uncomplicated nephrotic
syndrome.
In the periphery, edema is characteristically soft and easily
pitting and accumulates in areas of low interstitial tissue
pressure and high compliance, such as the periorbital areas.
It is usually worse about the face on arising and increases in
dependent areas with activity and upright posture.
Complications and General Management
EDEMA
Treatment of edema consists of mild sodium restriction
and, in selected cases, the judicious use of diuretics.
Many patients experience spontaneous diuresis during
recumbency.
Potent loop diuretics such as furosemide, bumetanide,
or ethacrynic acid have become popular, although
thiazide diuretics (hydrochlorothiazide or
chlorthalidone) may suffice in many cases.
Metolazone may be effective when used alone or in
combination with furosemide in severe or refractory
nephrotic edema.
Complications and General Management
EDEMA
Because marked kaliuresis may occur with the use of
these diuretics, a K+ sparing diuretic such as
spironolactone, amiloride, or triamterene may be
employed concomitantly to prevent hypokalemia.
However, these agents should not be used when GFR is
substantially decreased because of the danger of
precipitating hyperkalemia. Diuretics should be used
cautiously in patients with profound hypoalbuminemia.
Hyperoncotic salt-poor albumin infusions should be
reserved for patients for whom orthostatic hypotension
and hypovolemia are a significant problem or in cases of
severe and refractory edema.
Complications and General Management
EDEMA
Albumin infusions transiently increase plasma volume
and oncotic pressure and may restore diuretic
responsiveness, but most of the infused albumin is
excreted in the urine 24 to 48 hours after completion of
the infusion.
When plasma oncotic pressure is profoundly depressed
(less than 8 mm Hg), as in the case of severe
hypoalbuminemia, there may be a tendency for
accumulation of interstitial fluid even in the lowpressure pulmonary circuit.
Even minor increases in left atrial filling pressure may
induce florid pulmonary edema in such patients.
Complications and General Management
EDEMA
Treatment for this complication is similar to that for
the pulmonary edema of left ventricular failure, with
the addition of measures to increase plasma oncotic
pressure, while at the same time ensuring that left
atrial (pulmonary wedge) pressure is not further
increased.
The combination of intravenous furosemide and
hyperoncotic albumin infusion would seem to be a
reasonable therapeutic approach to this uncommon
problem.
Extracorporeal ultrafiltration is rarely, if ever,
required unless GFR is markedly reduced.
Hepatic cirrhosis
Hepatic cirrhosis presents clinically as ascites
and lower-extremity edema as a result of
portal hypertension and hypoalbuminemia.
Other signs of liver disease include:
jaudice, spider angiomas
palmar erythema
gynecomastia
TREATMENT
The management of ECF volume-expanded states is
dependent on the accurate diagnosis and treatment of
the underlying disorder
The cornerstones of therapy in these patients is
1) salt restriction
patients with mild volume expansion – 4g/day (172 mmol/day)
patients with moderate-to-severe ECF volume expansion – 2g/day
(86 mmol/day)
2) diuretics
3) restriction of daily fluid intake (the intake should be
adjusted to equal urinary losses and insensible loss
THE MANAGEMENT OF VOLUME –
EXPANDED STATES SHOULD AIM TO
CORRECT
THE
UNDERLUING
PRIMARY DISORDER
Drugs that predispose to salt retention or
alter the effect of diuretics need to be
discontinued
Classification of diuretics
Site of action
Proximal diuretics
Loop diuretics
Distal
convoluted
tubule diuretics
Collecting duct
diuretics
Acetozolamide
Metolazone
Furosemide
Bumetanide
Torsemide
Ethacrynic acid
Thiazides
Metolazone
Amiloride
Triamterene
Spironolactone
Classification of diuretics based
on predominant site of action
Type of diuretic
Site of
action
Carbonic anhydrase
inhibitor
Acetozolamid
Proximal
tubule
Potency Primary Secondary Complications
effect
effect
↑ K loss
↑ HCO 3 loss
+++
+++
↓ Na + /K +
/2Cl absorption
↑ K + loss
↑H+
secretion
Hypokalemic
alkalosis
++
++
++
↓ Na +
absorption
↑ K + loss
↑H+
secretion
Hypokalemic
alkalosis
+
+
+
↓ Na +
absorption
↓ K + loss
↓H+
secretion
Hyperkalemic
acidosis
+
Loop
Furosemide
Etacrynic acid
Loop of
Henle
Thiazide
Chlorthiazide
Distal
tubule
Hydrochlorothiazide
M etolazone
Potassium sparing
Collecting
Triamterene
duct
Amiloride
Spironolocatone
Hypokalemic
hyperchloremic
acidosis
↓ Na /K
exchange
+
+
+
Idiopathic edema
This syndrome occurs almost exclusivly in
women often with psychosocial difficulties, is
characterized by periodic episodes of edema,
frequently accompanied by abdominal distention
Fairly large, diurnal alterations in weigh occur,
so that the patient may weigh several pounds more
after having been in the upright posture for several
hour. This fact suggest an increase in capillary
permeability which appears to fluctuate in severity
and is aggrevated by hot weather.
Edema; Anasarca
Swelling involves the enlargement of organs,
skin, or other body structures caused by
excessive buildup of fluid in the tissues.
This buildup can lead to a rapid increase in
weight over a short period of time (days to
weeks).
Swelling can occur throughout the body
(generalized) or it may be limited to a specific
part of the body (localized).
Edema; Anasarca
Slight edema of the lower legs commonly occurs in
warm summer months, especially if a person has been
standing or walking a lot.
Generalized swelling, or massive edema (also called
anasarca), is a common sign in severely ill people.
Although slight edema may be difficult to detect,
especially in an overweight person, massive edema is
very obvious.
Edema can indicate a chronic and progressive medical
illness.
Edema; Anasarca
Edema may be generally described in one
of two ways:
Pitting edema -- When you press a finger
against a swollen area for 5 seconds and then
quickly remove it, an indentation is left that
fills slowly.
Nonpitting edema -- When you press a finger
against a swollen area for 5 seconds and then
quickly remove it, no indentation is left in the
skin.
Edema; Anasarca
Common Causes
Too much salt or sodium intake
Burns
Sunburn
Too little albumin in the blood (hypoalbuminemia)
Malnutrition
Pregnancy
Drugs
Androgenic and anabolic steroids
Antihypertensives
Corticosteroids such as prednisone (causes sodium retention)
Estrogens
Nonsteroidal anti-inflammatory drugs (see NSAIDs)
Calcium channel blockers
Nephrotic syndrome
Acute glomerulonephritis
Chronic kidney disease
Heart failure
Liver failure from cirrhosis
Thyroid disease
Edema; Anasarca
Medical history
Time pattern
When did you first notice this?
Is it present all the time?
Does it come and go?
Quality
How much swelling is there?
When you poke the area with a finger, does the dent remain?
Location
Is it overall or in a specific area (localized)?
If swelling is in a specific area, what is that area?
Other
What seems to make the swelling better?
What seems to make the swelling worse?
What other symptoms are also present?
Edema; Anasarca
Diagnostic tests that may be performed include the
following:
Albumin levels
ECG
Echocardiography
Serum electrolyte tests
Urinalysis
X-rays
Liver function tests
Kidney function tests
Edema; Anasarca
Treatment may include fluid and sodium
restriction, diuretics, or water pills.
fluid intake and output should be monitored,
and patient should be weighed daily.
„Avoid alcohol if liver disease (such as
cirrhosis or hepatitis) is causing the
problem.”
Vascular support hose may be advised.
Localized edema
due to venous or lymphatic obstruction may be
caused by
thrombophlebitis,
chronic lymphangitis
resection of regional lymph nodes,
filariaris etc.
Lymphedema is particularly intractable because
restriction of lymphatic flow results in increased
protein concentration in the interstitial fluid, a
circumstance which aggravates retention of fluid
Edema – peripheral
Swelling of the ankles - feet - legs; Ankle swelling; Foot swelling;
Leg swelling;
Peripheral edema is an abnormal buildup of fluids in ankle and
leg tissues.
Painless swelling of the feet and ankles is a common problem,
particularly in older people. It may affect both legs and may
include the calves or even the thighs.
Because of the effect of gravity, swelling is particularly
noticeable in the lower legs.
When the swollen area is squeezed, the fluid will move out of
the affected area and may leave a deep impression for a few
moments.
Swelling of the legs is many times related to systemic causes
(for example, heart failure, renal failure, or liver failure).
Edema – peripheral
Common Causes
Long airplane flights or automobile rides
Menstrual periods (for some women)
Sunburn
Generalized allergy
Prolonged standing
Injury or trauma to the ankle or foot
Venous insufficiency (varicose veins)
Pregnancy (mild to severe swelling)
Environmental
Burns
Insect bite or sting
Starvation or malnutrition
Edema – peripheral
Common Causes
Medical treatments
Body fluid overload
Infiltration of an IV site
Extremity surgery
Medications
Estrogens and progestin oral contraceptives
Blood pressure-lowering drugs
Certain antidepressants (such as Nardil)
Estrogen - oral
Long-term corticosteroid therapy
Nifedipine
Testosterone
Diagnostic tests
Venogram
Congestive heart failure
Glomerulonephritis or other kinds of kidney disorders
Edema – peripheral
Home Care
Elevate the legs above the heart while lying down.
Avoid sitting or standing without moving for prolonged
periods of time.
Avoid putting anything directly under the knees when lying
down, and don't wear constricting clothing or garters on
the upper legs.
Exercising the legs causes the fluid to work back into the
veins and lymphatic channels so that the swelling goes
down.
Elastic bandages or support stockings can provide pressure
to help reduce ankle swelling.
Edema – peripheral
Medical history questions documenting ankle, feet,
and leg swelling in detail include the following:
Location
What specific body part(s) swell?
Is there ankle swelling?
Is the whole foot swollen?
Is there swelling over the small bones of the feet?
Is there swelling of the toes?
Is the knee swollen?
Is the whole leg swollen?
Time pattern
Is the swelling always present?
Is it worse in the morning or the evening?
Edema – peripheral
Medical history questions documenting ankle, feet,
and leg swelling in detail include the following:
Aggravating and relieving factors
What makes it better?
Does the swelling go down when the legs are
elevated?
What makes it worse?
What other symptoms are also present?
The physical examination may include
emphasis on the heart, lungs, kidneys, and legs.
Edema – peripheral
Diagnostic tests that may be
performed include the following:
Blood tests such as a CBC or blood
chemistry (Chem-20)
ECG
Chest X-ray or extremity X-ray
Edema – peripheral
The specific treatment will be directed at
whatever underlying cause is found.
Diuretics may be prescribed. These are
effective in reducing the swelling but have
some side effects.
Home treatment for benign causes of leg
swelling should be tried before drug
therapy under medical supervision.
Facial swelling
Edema, central on the face
Puffy face;
Swelling of the face;
Moon face;
Facial edema
Facial swelling involves an accumulation of
fluid in the face, which may extend to the neck
and upper arms.
Facial swelling
If the facial swelling is mild, it may be hard to
detect.
it is important to note the following:
Whether there is pain
The duration of the swelling
What makes it better or worse
Any other symptoms that accompany the swelling
Facial swelling
Common Causes
Obesity
Allergic reaction (such as allergic rhinitis, hay fever, or a bee sting)
Conjunctivitis with swelling around the eye(s)
Stye with swelling around the infected eye
Malnutrition (when severe)
Sinusitis
Facial trauma or injury (such as burns)
Drugs including prolonged use or allergic reaction to aspirin, antipyretics, penicillin,
sulfa, glucocorticoids, or other drugs
Blood transfusion reaction
Head, nose, or jaw surgery
Angioedema from any cause including reaction to contrast media from radiologic tests
Cellulitis
Tooth abscess
Facial swelling
If facial swelling is caused by burns and/or respiratory distress is present,
emergency measures must be taken first. Then the medical history will be
obtained and a physical examination performed.
Medical history questions documenting facial swelling in detail may include
the following:
Time pattern
• How long has the facial swelling lasted?
• When did it begin?
What makes it worse?
What makes it better?
General health
• What is your height and weight?
• How is your diet?
Facial swelling
Other
• Has there been exposure to something to which the person may be allergic (an
antigen)?
• What medication(s) are you taking?
• Have you had recent facial injury?
• Have you had a recent test or surgical procedure?
• What other symptoms are also present? Especially, is there:
– Facial pain
– Sneezing
– Difficulty breathing
– Hives or rash
– Eye redness
– Fever
Diagnostic tests will be determined by other accompanying symptoms and
results of the physical examination.
Joint swelling
Swelling of a joint;
Knee swelling;
Toe swelling;
Finger swelling;
Hip swelling
Swelling occurs in the joints when fluid accumulates in
the soft tissue, such as "water on the knee."
Joint swelling may occur along with joint pain.
Joint swelling
Common Causes
Acute gouty arthritis (gout)
Chronic gouty arthritis
Rheumatoid arthritis
Trauma
Ankylosing spondylitis
Enteropathic arthropathy
Infection
Pseudogout
Psoriatic arthritis
Reiter's syndrome
Systemic lupus erythematosus
Hemarthrosis
Joint swelling
Medical history questions
Location
Which joint is swollen?
Is it the big toe?
Is the jaw or neck swollen?
Are multiple joints swollen?
Time pattern
When did the joint swelling develop?
Is it always present or off and on?
Is this the first time you have had swollen joints?
Quality
How swollen is the area?
If you press over the swollen area with a finger, does it leave a dent after
you take the finger away?
Joint swelling
Medical history
Aggravating factors
What makes the swelling worse?
Is it any worse in the morning or at night?
Does exercise make it worse?
Relieving factors
What make the swelling better?
Does elevating the affected body part make the swelling go down?
Is it better if you use an elastic wrap?
What home treatment have you tried? How effective was it?
Other
What other symptoms are also present?
Is there joint pain?
Is there fever?
Is there a rash?
The physical examination will include a detailed examination of the affected
joint(s).
Joint swelling
Diagnostic tests that may be performed
include the following:
Blood studies (such as a CBC or blood
differential)
Joint X-rays
Physical therapy for muscle and joint
rehabilitation may be recommended.
Angioedema
Angioneurotic edema; Swelling - eyes
The development of large welts below the
surface of the skin, especially around the
eyes and lips.
The welts may also affect the hands, feet,
and throat.
The condition is associated with allergies
and histamine release.
Angioedema
Common allergens include:
medications
foods (such as berries, shellfish, fish, nuts, eggs, milk, and
others)
pollen
animal dander (scales of shed skin)
insect bites
exposure to water, sunlight, cold or heat
emotional stress
Hives and angioedema may also occur after infections or
illness (including autoimmune disorders, leukemia, and
others).
Angioedema
Symptoms
sudden development of wheals or welts
usually located on the eyes and mouth, but may also occur on the
hands and feet or in the throat
red
itching or painful
blanch and swell if irritated
deep
localized edema (eyes and mouth appear swollen)
abdominal cramping
difficulty breathing
chemosis (swollen conjunctiva)
Angioedema
Signs and tests
The diagnosis is primarily based on the
appearance of the skin and a history of
exposure to an irritant/allergen.
There may be stridor (crowing sound
when inhaling) if the throat is affected.
Rarely, allergy testing may be performed
to determine the causative allergen.
Angioedema
Treatment
Mild symptoms may not need treatment.
Moderate to severe symptoms may need treatment.
Difficulty breathing or stridor indicates an emergency condition.
Self-care includes cool compresses or soaks to the area to provide
pain relief and reduce symptoms.
Medications to reduce the allergic response and associated
symptoms include antihistamines, adrenaline (epinephrine),
terbutaline, cimetidine, corticosteroids, sedatives, and
tranquilizers.
For an emergency condition, protect the airway. At the hospital,
there may be a need for intubation (placement of a tube in the throat to
keep the airway open).
To prevent recurrence of angioedema avoid irritating the affected
area, avoid known allergens, and avoid temperature extremes.
Angioedema
Complications
Angioedema that does not affect the
breathing may be uncomfortable, but it
generally is harmless and resolves itself in
a few days.
life-threatening airway obstruction (if
swelling occurs in the throat)
anaphylactic reaction
Edema of Nutritional Origin
A diet grossly deficient in protein over a prolonged period
may produce hypoproteinemia and edema.
The latter may be intensified by the development of
beriberi heart disease, also of nutritional origin, in which
multiple peripheral arteriovenous fistulas result in reduced
effective systemic perfusion and effective arterial blood
volume, thereby enhancing edema formation.
Edema may actually become intensified when these
famished subjects are first provided with an adequate diet.
The ingestion of more food may increase the quantity of
salt ingested, which is then retained along with water.
Edema of Nutritional Origin
So-called "refeeding edema" may also be
linked to increased release of insulin, which
directly increases tubular sodium
reabsorption.
In addition to hypoalbuminemia,
hypokalemia and caloric deficits may be
involved in the edema of starvation.
Other Causes of Edema
These include hypothyroidism, in which the
edema (myxedema) may be located typically
in the pretibial region and which may also be
associated with periorbital puffiness.
Exogenous hyperadrenocortism, pregnancy,
and administration of estrogens and
vasodilators, particularly the calcium
antagonist nifedipine, may also all cause
edema.
Effect of hemodynamic
changes on proximal
tubule solute transport: a
summary.
Hemodynamic
mechanisms by which a
reduction of effective
arterial volume causes
salt and water retention
and thereby contributes
to the formation of edema
Sequence of events
leading to the
formation and
retention of salt
and water and the
development of edema.
ANP, atrial natriuretic
peptide; RPF,
renal plasma flow;
GFR, glomerular
filtration rate.
Inhibitory influences
are shown by broken
lines. ADH,
antidiuretic hormone.