Flashcards in Exam #2: Hemodynamics I Deck (48):
What are hemodynamic disorders?
Generally, hemostasis maintains the fluid portion of the CV system in balance; failure of hemostasis mechanisms that can lead to:
- Excessive bleeding
- Vessel occlusion by excessive blood clot formation
Describe normal fluid hemostasis.
- Fluid flows out of the arterial end of microcirculation into the ISF
- Fluid returns at the venous end of microcirculation
Whatever is leftover goes into the lymphatic system & is drained into the thoracic duct-->subclavian vein
What is edema?
Increased ISF that cannot be completely dealt with by the lymphatics
What is the difference between transudate and exudate?
Transudate= edema caused by increased capillary hydrostatic pressure or reduced plasma protein, which results in protein-poor fluid with a low specific gravity ( <1.012)
What is a hydrothorax?
Fluid in the pleural space
What is hydropericardium?
Fluid is the space between the heart and pericardium
What is hydroperitoneum?
Ascites, fluid in the peritoneal space
What are the five potential etiologies of edema?
1) Increased hydrostatic pressure
2) Decreased plasma oncotic pressure (low protein)
3) Sodium & water retention
4) Lymphatic obstruction
Draw the algorithm that outlines the etiologies of edema.
What generally causes edema resulting from a generalized increase in hydrostatic pressure?
Congestive heart failure-->compromised right ventricular function causes backup in the venous circulation
What is pitting edema?
Finger-shaped depression remaining after pressing on skin with a finger
What protein is mostly responisble for maintaining colloid osmoitc pressure?
What causes hypoalbuminemia?
2) Decreased hepatic synthesis i.e. liver failure or cirrhosis
3) Nephrotic Syndrome
What is ascites commonly caused by?
Advanced liver cirrhosis
What is anasarca?
A term that describes severe general edema that is usually due to a lack of oncotic pressure
What is the earliest sign of anasarca?
How does Na+ retention lead to edema?
- Increased Na+ in the circulation causes an obligate associated shift of water intravascular space
- The effect is 2-fold: 1) increased in hydrostatic pressure due to volume expansion, & 2) dilution of intravascular fluid & deceased oncotic pressure
- Edema results
How does inflammation lead to edema?
Increased vascular permeability leads to a leaking of fluid into the extracellular space
*****Note that this fluid is PROTEIN-RICH & called "Exudate"
What does lymphatic obstruction lead to? What are two of the common causes of lymphedema?
Lymphedema i.e. edema resulting from any type of lymphatic obstruction
1) Inflammation w/ fibrosis-->filariasis
A 65 y/o female s/p left radical mastectomy presents to you complaining of severe edema of the left arm. What is the most likely cause an explanation of her edema?
Surgical removal of axillary lymph nodes during radical mastectomy can lead to significant lymphedema of the UE of the effected side b/c drainage is impaired.
What is elephantiasis?
Severe edema of the external genitalia & lower limbs due to "Filariasis" cased by parastic infection, most commonly Wuchereria bancrofti
- Parasite--> inguinal lymphatic & node fibrosis
- Obstruction of lymph drainage
Describe the microscopic appearance of edema.
Usually just see clearing and separation of the ECM elements, but you may see pink staining if protein content is significant
- High protein= pink
What is the clinical relevance of subcutaneous edema?
Subcutaneous edema is seldom of clinical significance, but it can:
- Interference of healing
- Increase risk of infection and ulceration
What are the two anatomical sites that are clinically important in terms of edema?
What are the three most common causes of cardiogenic pulmonary edema?
1) Systemic HTN (leading to:)
2) Left ventricular failure
List the common causes of noncardiogenic pulmonary edema. Try to use the mnemonic.
N= Near drowning
O= O2 therapy
A= Allergic alveolitis
R= Renal failure
I= Inhaled toxins
What are the symptoms of pulmonary edema?
Generally, remember that pulmonary edema= DYSPNEA + COUGH. More specifically, manifestations associated with those two primary symptoms include:
- Cyanosis (central)
- "Air hunger"
- Blood tinged
What are the physical signs of pulmonary edema?
2) Bounding pulse
3) Crackles/ Rales
What is the difference between interstitial & alveolar pulmonary edema?
Alveolar= airspace/ air sac edema
Interstitial= branching pulmonary arteries
Review the radiographic differences between interstitial and alveolar pulmonary edema.
Alveolar= radiolucent, fluid accumulation in the alveoli obscure normal anatomy
Interstitial= radiodense, there prominent lung markings with aerated lungs
What are the microscopic features of pulmonary edema?
- Pink fluid
- Hemosiderin laden macrophages or "heart failure cells"
- Thick septa
What is tonsillar herniation?
Herniation of the brainstem into the foramen magnum that can be caused by cerebral edema
What are the localized causes of cerebral edema?
What is the most common cause of an epidural hematoma?
Arterial rupture i.e. trauma causing damage to the middle meningeal a.
What is the most common cause of a subdural hematoma?
What is the most common cause of subarachnoid hemorrhage?
Intraparenchymal hemorrhage into the brain tissue
What are the generalized causes of cerebral edema?
2) HTN crisis
3) Obstruction of venous outflow
Review the different types of herniation that may occur as a result of cerebral edema.
Subfalciform= innermost part of the frontal lobe is scraped under part of the falx cerebri, the dura mater at the top of the head between the two hemispheres of the brain
Transtentorial= innermost part of the temporal lobe, the uncus, can be squeezed so much that it moves towards the tentorium and puts pressure on the brainstem, most notably the midbrain
Tonsillar= Brainstem herniation through the foramen magnum
What is hyperemia?
An ACTIVE process of arterial dilation that results in increased oxygenated blood flow to a tissue
*Tissue is erythematous due to engorgement with oxygenated blood
What is congestion?
A PASSIVE process due to impaired OUTFLOW of blood from a tissue
*Tissue is blue-red (purple) due to accumulation of deoxygenated hemoglobin i.e. cyanosis
What is chronic passive congestion? What are the potential outcomes of chronic passive congestion?
Long-term congestion that results in stasis, cellular degeneration, and death
- Capillary rupture at these sites can result in small foci of hemorrhage
- Capillary rupture, breakdown, and phagocytosis of RBC debris--> "hemosiderin-laden macrophages" at the site
Thus, hemosiderin-laden macrophages or heart failure cells = chronic congestion
Describe the microscopic appearance of chornic pulmonary congestion.
- Thickened & fibrotic septa
- Heart failure cells i.e. "hemosiderin-laden macrophages" in alveolar spaces
What is hepatic congestion?
Right ventricular failure leading to backup of blood into the central regions of the hepatic lobules
What is the term for chronic hepatic congestion?
Nutmeg liver i.e. central regions of hepatic lobules that are grossly red/brown & depressed due to cellular loss, surrounded by unaffected areas
What is a hematoma?
Collection of blood under the skin
How are hematomas classified?
Purpura= in between
What should you think with petechiae that DO NOT blanch?