Edema and Congestion

peripheral edema?

can be bilateral or unilateral an example of gravity alone causing increased venous hydrostatic pressure is socks on ankles/feet! can be seen after sitting/standing with minimal activity, where venous blood pools and increases hydrostatic pressure! will go away upon walking

what is lymphedema?

occurs when the amount of edema in the interstitial tissue exceeds the ability of the lymphatic system to drain it in equation: decrease in lymph drainage leads to increase in accumulation of fluid in the interstitium.

clinical features of lymphedema?

- usually unilateral -- upper and lower limbs - made worse by prolonged dependency (gravity) - physical exam: - increased diameter of the limb - edema may be pitting, brawny, or weeping - sensory/range of motion problems - increased risk for infections (due to inability to properly drain the site of infection!) left: marked edema in the lower limb secondary to surgical trauma as noted by scars above the ankle. what we don't see is the destruction of inguinal lymph nodes. middle: upper limb edema following axillary lymph node dissection, most likely due to breast cancer. right: *lymphatic filariasis* or elephantiasis involving the scrotum and lower limb changes are not subtle...

what is venous congestion?

- venous blood engorgement (filling) of an organ - congestion often accompanies edema and may precede it - organs/tissues appear *cyanotic* (blue/purple) - increased organ weight/size

pitting edema?

= cutaneous edema. increased accumulation of interstitial fluid in the extremities. pitting refers to the fact that when pressure is applied the indentation (pit) remains after the pressure is released.

what is hyperemia?

= increased blood flow in an organ or tissue opening of precapillary sphincters in hypoxia, decreased pH due to CO2, increased temp, increased K+ ions.

Which one of the following best defines the mechanism of systemic edema in a patient with severe loss of protein in the urine (i.e. proteinuria)?

Decrease of intravascular oncotic pressure

An edematous upper limb following a mastectomy and axillary dissection for breast cancer is best explained by?

Destruction of lymphatics

interstitial fluid accumulation equation?

IFA = K[Pc-Pif] - x[Op-Opif] - Qlymph comes out at ~14mL/min. enters back into venule at ~12 mL/min. so, about 2mL/min goes into the lymphatics! at the arteriole end, hydrostatic pressure is high and oncotic pressure is low. at the venule end, hydrostatic pressure is low and oncotic is high. you've gotten rid of water so protein conc is higher and it wants to pull water back in! K=permeability coefficient. approx 1 normally. marked increase during *inflammation* which accounts for the swelling! Pc=intravascular hydrostatic pressure that pushes fluid out. Pif = interstitial hydrostatic pressure that pushes fluid back in Op=plasma oncotic pressure. under normal circumstances the interstitial fluid returns to blood via the postcapillary venules. this is due to plasma oncotic pressure of 25mmHg pulling it back in. Opif=interstitial oncotic pressure Qlymph=lymphatic flow returns extra fluid to vasculature via lymph vessels

Which of the following best defines the mechanism of pulmonary edema following a MI?

Increase of hydrostatic pressure

what causes pulmonary edema?

LEFT heart failure. inability of left heart to pump out appropriate volume of blood with each contraction. could be disease of aortic/mitral valves, damage to cardiac muscle fibers by infarction (ischemic injury) or infection (myocarditis) that weakens the heart. end result = blood backs up into the pulmonary veins of the lung increasing hydrostatic pressure within the pulmonary capillaries that form the thin walls of the alveoli.

A finding of alveolar macrophages filled with hemosiderin is commonly associated with which one of the following?

Left heart failure (macrophages take up RBCs that enter the alveoli and break down the hemoglobin and store iron as hemosiderin)

Which of the following would best explain liver congestion?

Right ventricle failure (the blood returning to heart would be backed up in liver)

active hyperemia vs passive hyperemia?

active = increased blood flow in tissue/organ most commonly associated with exercise and inflammation (associated with vascular dilatation secondary to exercise/inflammation) passive (congestion) = pooling of venous blood

pulmonary edema/congestion?

can see pulmonary congestion on x-ray as cloudiness resulting from left heart failure. patients have respiratory difficulties related to the pulmonary edema that accompanies left heart failure and congestion. these patients are short of breath (dyspnea) and cannot lie flat in bed (orthopnea)

clogged pipes?

cause of the "blue leg" on left is venous thrombosis -- clotting of the blood -- that prevents venous drainage from lower limb. rare condition. more common is venous stasis (right) due to defective valves in the large veins of the lower limb that leads to high venous pressures.

hepatic congestion histology?

classic appearance of congested liver is similar to that of a nutmeg; thus a nutmeg liver. brown color seen in fixed section represents blood expanding to hepatic sinuses. better seen at right! pink hepatocytes spread apart and sinuses filled with blood. can get very large due to right heart failure.

right sided heart failure (pump failure)?

congestion of liver, spleen, lower limbs (these organs contain a lot of blood). comes with edema

what does hemosiderin pigment in sputum mean?

congestive heart failure

histology of pulmonary congestion?

dark/cyanotic appearance of lung associated with congestion. can see upper right pulmonary edema filling the alveoli and alveolar capillaries that are engorged with erythrocytes (arrows). the lower right image shows chronic pulmonary congestion with widening of alveolar septa (arrows) and alveolar macrophages packed with hemosiderin pigment!

causes of decreased oncotic pressure?

decreased serum protein concentration due to: increased protein (albumin) loss - nephrotic syndrome - proteinuria - gastroenteropathy - diarrhea decrease protein (albumin) synthesis - hepatic cirrhosis - malnutrition excess IV fluid resuscitation (increased volume of fluid dilutes protein content)

why does excess fluid accumulate in extravascular tissue/interstitium?

due to: 1. increased vascular permeability 2. increased hydrostatic pressure 3. decreased oncotic pressure 4. and/or obstruction of lymph vessels

right sided heart failure?

enlarged right ventricle (looks like a tennis shoe) physical exam: cyanosis, distention of jugular vein (arrow), an enlarged liver (hepatomegaly) and spleen (splenomegaly). there may be a fluid wave indicative of ascites, and pitting edema in the lower limbs. venous blood pressure is usually elevated.

causes of increased hydrostatic pressure?

impaired venous return - hepatic cirrhosis - pulmonary edema due to congestive heart failure venous obstruction - lower limb inactivity (gravity) - thrombosis - mass backup of venous blood! this increases the hydrostatic pressure in the microvasculature, thus increasing the net outward filtration of fluid into the interstitium.

what is edema?

increased fluid in the extravascular or interstitial tissue

explain movement of fluid across the endothelium?

it is bidirectional! hydrostatic (=hemodynamic) pressure "pushes" fluid out at the arteriole side of the microvasculature. then, fluid reenters the circulation at the venule end! oncotic pressure (directly proportional to protein concentration in the serum) "draws" fluid back into the vascular channel. at arteriole end, it's the hydrostatic pressure (NOT bp) that pushes the fluid out. small interstitial pressure offsets this. at the venule end, fluid comes back in due to *oncotic pressure*. not all of the fluid moves back at the venule end, there's some leftover that has to leave via the lymphatic vessels.

causes of pitting edema?

kidney disease, thrombosis (clot) in a vein, inflammation of a vein (thrombophlebitis). mass obstruction of the venous return from the lower limbs (pregnancy). congestive heart failure could lead to right heart failure, thus causing a backup of blood returning to the heart from the limbs and thus pitting edema.

what is anasarca?

left baby: systemic edema (anasarca) due to decreased oncotic pressure due to malnutrition, Kwashiorkor. baby was breast fed until the mother became pregnant and delivered a new baby. this infant was taken off the mother's breast milk and fed carbs no protein! right child: anasarca due to kidney failure secondary to malaria

what is congestion?

pooling of blood in the *venous* circulation that can occur alone, or in conjunction with edema in several clinical settings

causes of lymphedema?

primary - congenital - hereditary secondary - infection/inflammation - obstruction/fibrosis (trauma, surgery, tumors, radiation therapy) - surgical dissection (lymphadenectomy) - chronic venous insufficiency

left sided heart failure (pump failure)?

pulmonary congestion. comes with edema

what is pulmonary edema?

refers to fluid accumulation in the alveoli. can be transudate or exudate. autopsy demonstrate the frothy nature of the transudate when the lungs are pressed. normal lung = upper right. clear open spaces = alveoli where the gas exchange occurs. alveolar space is extravascular space. pink staining (eosinophilic material -- proteaceous due to surfactant) in the alveoli represents pulmonary edema.

ascites?

severe ascites patient with bulging abdomen. pressing on the abdomen elicits a fluid wave, and a difference in the percussion as the patient is turned on their side! ascites refers to a fluid (either transudate [more commonly] or an exudate [exudate = increased endo cell permeability with inflammation]) accumulation in abdominal cavity. at the extreme, it can be >20L. ascites that are transudates arise from cirrhosis of the liver, which increases the hydrostatic pressure in the portal vein backward into the microvasculature, forcing more fluid out. cirrhosis causes scarring of the liver that can destroy the normal architecture. "cobblestone appearance". the nodules consist of regenerating liver cells (hepatocytes) surrounded by dense CT. trichrome stain = CT blue. with H&E. destruction of normal architecture causes compression of branches of portal vein in liver. venous blood entering the liver is then backed up into the microvasculature that feeds into the portal vein (stomach!!! -- why his abdomen is swollen) liver disease also decreases serum oncotic pressure which also contributes.

what causes venous congestion?

think "pump failure" (heart) or "clogged pipes" (veins)