Chapter 036. Edema (Part 5) ppsx

Chapter 036. Edema
(Part 5)

Idiopathic Edema
This syndrome, which occurs almost exclusively in women, is
characterized by periodic episodes of edema (unrelated to the menstrual cycle),
frequently accompanied by abdominal distention. Diurnal alterations in weight
occur with orthostatic retention of NaCl and H
2
O, so that the patient may weigh
several pounds more after having been in the upright posture for several hours.
Such large diurnal weight changes suggest an increase in capillary permeability
that appears to fluctuate in severity and to be aggravated by hot weather. There is
some evidence that a reduction in plasma volume occurs in this condition with
secondary activation of the RAA system and impaired suppression of AVP
release.
Idiopathic edema should be distinguished from cyclical or premenstrual
edema, in which the NaCl and H
2
O retention may be secondary to excessive
estrogen stimulation. There are also some cases in which the edema appears to be
diuretic-induced. It has been postulated that in these patients chronic diuretic
administration leads to mild blood volume depletion, which causes chronic
hyperreninemia and juxtaglomerular hyperplasia. Salt-retaining mechanisms
appear to overcompensate for the direct effects of the diuretics. Acute withdrawal
of diuretics can then leave the Na
+
-retaining forces unopposed, leading to fluid
retention and edema. Decreased dopaminergic activity and reduced urinary
kallikrein and kinin excretion have been reported in this condition and may also be
of pathogenetic importance.

Idiopathic Edema: Treatment
The treatment of idiopathic cyclic edema includes a reduction in NaCl
intake, rest in the supine position for several hours each day, and the wearing of
elastic stockings (which should be put on before arising in the morning). A variety
of pharmacologic agents, including angiotensin-converting enzyme inhibitors,
progesterone, the dopamine receptor agonist bromocriptine, and the
sympathomimetic amine dextroamphetamine, have all been reported to be useful
when administered to patients who do not respond to simpler measures. Diuretics
may be helpful initially but may lose their effectiveness with continuous
administration; accordingly, they should be employed sparingly, if at all.
Discontinuation of diuretics paradoxically leads to diuresis in diuretic-induced
edema, described above.
Localized Edema
(See also Chap. 243) Edema originating from inflammation or
hypersensitivity is usually readily identified. Localized edema due to venous or
lymphatic obstruction may be caused by thrombophlebitis, chronic lymphangitis,
resection of regional lymph nodes, filariasis, etc. Lymphedema is particularly
intractable because restriction of lymphatic flow results in increased protein
concentration in the interstitial fluid, a circumstance that aggravates retention of
fluid.
Generalized Edema
The differences among the three major causes of generalized edema are
shown in Table 36-2.
Table 36-2 Principal Causes of Generalized Edema: History, Physical
Examination, and Laboratory Findings
Organ
System
History Physical
Examination
Laboratory

Findings
Cardiac

Dyspnea
with exertion
prominent—often
associated with
orthopnea—or
paroxysmal
nocturnal dyspnea
Elevated
jugular venous
pressure, ventricular
(S
3
) gallop;
occasionally with
displaced or
d
yskinetic apical
pulse; peripheral
cyanosis, cool
extremities, small
pulse pressure when
severe

Elevated urea
nitrogen-to-creatinine
ratio common; elevated
uric acid; serum sodium

often diminished; liver
enzymes occasionally
elevated with hepatic
congestion
Hepatic

Dyspnea
infrequent, except if
associated with
significant degree of
ascites; most often a
history of ethanol
Frequently
associated with
ascites; jugular venous
pressure normal or
low; blood pressure
lower than in renal or
If severe,
reductions in serum
albumin, cholestero
l,
other hepatic proteins
(transferrin, fibrinogen);
liver enzymes elevated,
abuse cardiac disease
; one or
more additional signs
of chronic liver
disease (jaundice,

palmar erythema,
Dupuytren's
contracture, spider
angiomata, male
gynecomastia;
asterixis and other
signs of
encephalopathy) may
be present
depending on the cause
and acuity of liver
injury; tendency toward
hypokalemia,
respiratory alkalosis;
macrocytosis from
folate deficiency
Renal Usually
chronic: may be
associate
d with
uremic signs and
symptoms,
including decreased
appetite, altered
Blood
pressure
may be elevated;
hypertensive or
diabetic retinopathy in
selected cases;

nitrogenous fetor;
periorbital edema may
Albuminuria,
hypoalbuminemia;
sometimes, elevation of
serum crea
tinine and
urea nitrogen;
hyperkalemia, metabolic
acidosis,
(metallic or fishy)
taste, altered sleep
pattern, difficulty
concentrating,
restless legs or
myoclonus; dyspnea
can be present, but
generally less
prominent than in
heart failure
predominate;
pericardial friction rub
in advanced cases
with uremia
hyperphosphatemia,
hypocalcemia, anemia
(usually normocytic)

Source: From Chertow.
The great majority of patients with generalized edema suffer from advanced

cardiac, renal, hepatic, or nutritional disorders. Consequently, the differential
diagnosis of generalized edema should be directed toward identifying or excluding
these several conditions.