Pathophysiology 1

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A freely movable, intravascular mass that is carried from one anatomic site to another by the blood. (Becomes a thrombus once it stops)

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embolism

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-these represent fragments of thrombi carried by venous or arterial blood. Infected thrombi give rise to septic emboli.

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Thromboemboli

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these include fat emboli that occur after bone fracture, and amniotic fluid emboli caused by the entry of amniotic fluid into the uterine veins during delivery.

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liquid emboli

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an air embolism can be produced by injecting air into veins. Air that is liberated under pressure, as in decompression sickness is yet another form.

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gaseous emboli

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like cholesterol crystals can detach from atherosclerotic plaques, as well as from tumor cells, bone marrow emboli, or bullets.
The clinical significance of emboli lies in the fact that all emboli can occlude blood vessels thus interrupting the blood supply to an organ.

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solid particle emboli

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#1 tumor that can block vessels

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renal cell carcinoma

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which accounts for most of the emboli in clinical practice, are classified on the basis of the vessels through which they are carried in the blood.

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thromboemboli

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originate in the left atrium or ventricle, aorta, and the major arteries.
They are carried by arterial blood and are important causes of infarction resulting from the occlusion of peripheral arteries.

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arterial emboli

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are venous emboli that reach the arterial circulation through the foramen ovale or an interventricular septal defect that can cause symptoms similar to those of arterial emboli.

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paradoxical emboli

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#1 place for arterial emboli is the ______, other places: Spleen, kidney, intestines, periphery (lower leg)

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brain

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-#1 cause of pulmonary embolism:
#2

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stasis and immobility, post trauma

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often lethal because they prevent the entry of blood into the lungs and cause acute anoxia.

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saddle emboli

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Smaller emboli lodge in the minor branches of the pulmonary vascular tree and cause pulmonary infarcts. These infarcts are triangular or _________-shaped, are subpleural, and can cause irritation of the pleura, associated with sharp pleuritic pain, accentuated with inspiration.

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wedge

Front 14

Are common causes of ischemia in various organs and most originate from the endocardium or from valvular thrombi.
In cases of bacterial endocarditis, the emboli may be infected.
Other sources are thrombi from ulcerated atherosclerotic plaques of the aorta and its major branches.

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arterial embolism

Front 15

fragmented inside the vessels because arterial blood flows fast and disrupts them and so they tend to lodge in medium-sized and smaller arteries.
The greatest risk is associated with emboli of the cerebral circulation, which typically lodge in the middle cerebral artery and causes infarcts of the basal ganglia.

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arterial embolism

Front 16

Other organs commonly affected by _________ are the splenic infarcts (sharp subcostal pain), renal infarcts (associated with hematuria), and intestinal infarcts (results from a embolus that lodges in one of the major intestinal arteries, causing gangrene and necrosis of the bowel).

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arterial emboli

Front 17

fat embolism: Describes the release of emboli of fatty marrow into damaged blood vessels following severe trauma to fat-containing tissue, particularly with bone fractures.
In most instances, it is clinically inapparent.
Fat embolism syndrome appears 1-3 days after the injury, and in its most severe form is characterized by

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respiratory failure

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Also characterized by mental changes, thrombocytopenia, and widespread petechiae.
The lungs typically exhibit changes of ARDS and microscopically show numerous fat globules within the microvasculature.
The lesions in the brain include cerebral edema, red petechiae and microinfarcts, with fat globules also seen in the microvasculature.

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fat embolism

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Decreased platelets (thrombocytopenia)
Adult respiratory distress syndrome = hylin membrane disorder (in newborn, fibrin)
Petechiae: small blood
TRIAD of fat embolism:

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ARDS, petechiae, microinfarcts

Front 20

Usually considered a direct result of trauma, with fat entering ruptured capillaries at the site of the fracture.
The platelets adhere to the fat globules, causing ___________.
Although this occurs in about 90% of patients with severe skeletal injuries, less than 10% of such patients have clinical findings.

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fat embolism, thrombocytopenia

Front 21

fetal cells and debris into the maternal circulation through a tear in the placental membranes and rupture of the open uterine and cervical veins.
A rare maternal complication of childbirth, but when it occurs it is often catastrophic.

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amniotic fluid embolus

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The classic findings are the presence of epithelial squamous cells shed from fetal skin, lanugo hair and fat from vernix caseosa within the pulmonary vasculature.
The onset is characterized by sudden severe dyspnea, cyanosis and hypotensive shock, followed by seizures and coma. If the pt survives, pulmonary edema develops, along with DIC (release of thromboplastins)

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amniotic fluid embolus

Front 23

these emboli, complete with hematopoietic cells and fat, are often seen in the lungs at autopsy.
They are usually encountered after cardiac resuscitation, a procedure in which fractures of the bones of the sternum, thorax and ribs are common.
There are no symptoms related to this event

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bone marrow embolism

Front 24

Air may be introduced into the venous circulation through neck wounds, thoro-centesis, punctures of the great veins during invasive procedures, and hemodialysis.
Small amounts of circulating air in the form of bubbles are of little consequence, but ____cc or more can lead to sudden death.
The bubbles act like physical obstructions which coalesce to form larger frothy masses

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air embolism, 100 cc

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these physically obstruct the flow of blood in the right side of the heart, the pulmonary circulation, and the brain.
On histologic exam, bubbles of air, which appear as empty spaces, can be seen in the capillaries and small vessels of the lungs.

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air bubbles

Front 26

A unique form of gas embolism, seen in persons exposed to increased atmospheric pressure, as in scuba divers and underwater drillers.
During descent, large amounts of inert gases (nitrogen or helium) are dissolved in body fluids. When the diver ascends, the gas is released from solution and exhaled.

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decompression sickness

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If the ascent is too rapid, gas bubbles form in the circulation and within tissues, obstructing blood flow and directly injuring cells.
______________, commonly known as the “bends”, is characterized by temporary muscle and joint pain to coma, owing to small vessel obstruction in these tissues.

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acute decompression sickness

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Refers to chronic decompression sickness in which the vascular obstruction causes multiple foci of ischemic (avascular) necrosis of bone, particularly affecting the head of the femur, tibia and humerus.
This complication was originally described in construction workers in diving bells.

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Caisson Disease

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Denotes an accumulation of blood in the peripheral circulation.
The resultant influx of blood into the capillaries.
Typically occurs in acute inflammation, blushing or exercise, and is separated into two types

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hyperemia, active and passive

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a consequence or dilatation of the arterioles and mediated by neural signals that lead to the relaxation of arteriolar smooth muscle.

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active hyperemia

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caused by an increased venous back pressure and most often occurs in a chronic form.
Typically a consequence of CHF, where the stagnation of venous deoxygenated blood contributes to a bluish discoloration of the tissues (cyanosis) and is often associated with peripheral or pulmonary edema.

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passive congestive/hyperemia

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Chronic passive congestion of the lungs leads to the formation of edema and extravasation of the RBC’s into the alveoli.
The disintegration of RBC’s are taken up by the alveolar macrophages and the hemoglobin of the RBC is degraded into a brown pigment (__________), which accumulates in the lysosomes of macrophages.

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hemosiderin

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These macrophages are called ‘__________________-” and are recognized in tissue sections of lungs histologically.
Chronic passive congestion is accompanied by anoxia and often results in pulmonary fibrosis.
There is also passive congestion of the liver which reveals centrilobular congestion around the central veins histologically.

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heart failure cells

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or passage of blood outside of the cardiovascular system.
Depending on the source, is can be classified as cardiac, aortic, arterial or venous.
Clinically, it may be of sudden onset (acute), or it may be long-standing (chronic), or it may be recurrent with repeated episodes of blood loss.

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extravasation / hemorrhage

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The classification of hemorrhage is:
1. _______: resulting from a GSW or stab wound and is often fatal. A softened heart muscle from an MI can result in a ventricular rupture and pericardial tamponade.
2. _________: can be caused by trauma, aortic aneurysm dilation and rupture which can lead to massive thoracic or abdominal hemorrhage.

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cardiac, aortic

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are often caused by penetrating wounds inflicted by bullets or knife wounds. Fractured bones may also tear arteries, and in any cases, the blood squirts out under arterial pressure, and unless stopped, it is usually fatal

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arterial hemorrhage

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is usually traumatic in which the blood either flows out of the body, resulting in exsanguination and a marked reduction in blood volume (Hypovolemia).

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venous hemorrhage

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what type of hemorrhage: Blood released by internal hemorrhage may fill various body cavities and form hematomas. Small hemorrhages into the skin and mucosa that are less than 1mm in diameter are called Petechiae, and those that measure 1mm. to 1cm. In diameter are termed Purpura. Larger, blotchy bruises are termed Ecchymoses.

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venous

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hemorrhage <1mm

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petechia

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hemorrhage 1mm - 3cm

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purpura

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hemmorrhage >3cm

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ecchymoses

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Massive acute hemorrhages should be treated as a ___________.
Most adults can lose 500 ml’s of blood without any adverse consequences, but losses of 1000-1500 ml’s of blood may result in profound circulatory shock, and losses over 1500 ml’s may be fatal.

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life-threatening event

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The transformation of the fluid blood into a solid aggregate encompassing blood cells and fibrin.

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thrombosis

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Fibrin is polymerized fibrinogen and forms a meshwork of thin filaments that bind together the cellular elements of the blood, forming a ________ or clot.

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thrombus

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Thrombi only form in living organisms and are the end product of a coagulation sequence which is normally activated to prevent blood loss from disrupted vessels.
When the same coagulation sequence is activated in intact vessels, pathologic intravascular thrombosis develops.
Normal intravascular coagulation is the result of the interaction of three factors:

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1) coagulation proteins
2) endothelial cells
3) platelets

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In the sequence of coagulation, these factors act on each other to form Thrombin. Thrombin acts as a catalyst, promoting the polymerization of Fibrinogen into Fibrin. The meshwork of fibrin represents the framework for the clot, which includes all the blood cells and many plasma proteins.

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coagulation proteins

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A thrombus attaches to the vessel wall, reflecting the fact that the coagulation factors of the plasma are inter-acting with the endothelium. Normal, resting endothelial cells have an antithrom-botic function. In inflammation or trauma, if activated, endothelial cells can initiate coagulation by means of mediators of inflammation, such as Interleukin-I &TNF.

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endothelial cells

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participate in clotting by neutralizing anticoagulation factors while promoting clotting. The thrombi formed under normal circumstances are typically small and short-lived. Pathologic thrombi disrupt the circulation and have serious consequences for the organs in which they have been formed.

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platelets

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are attached to the mural endocardium of the heart chambers and are commonly found overlying a MI.

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intramural thrombi

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are attached to the arterial wall and typically cover ulcerated atheromas in an atherosclerotic aorta or the coronary arteries.

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arterial thrombi

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are usually found in dilated veins (varicose veins). Long-standing venous thrombi are organized by granulation tissue, which may give an impression of inflammation (thrombophlebitis).

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venous thrombi

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are found in arterioles, capillaries, and venules, are typical of Disseminated Intravascular Coagulation.

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microvascular thrombi

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thrombi are classified as either red thrombi, which are composed of tightly intermixed RBC’s and fibrin, or layered thrombi, which show distinct layering of cellular elements and fibrin…the white layers in these thrombi are called the “_________”.
Thrombi in small vessels tend to be red.

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Lines of Zahn

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Thrombi in larger arteries and veins, as well as mural thrombi, tend to be _______.
Histologically, all thrombi consists of RBC’s that appear dark red, as well as lighter red strands of fibrin. Nucleated cells and platelets are intermixed with the fibrin and RBC’s.
Most small thrombi are lysed with no consequences, but larger thrombi remain attached to the surface of the vessel wall or endocardium.

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layered

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Initially, the attachment of these larger thrombi is mediated by the actions of adhesion molecules, such as _______.

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fibrin

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With time, the thrombus stimulates the in-growth of inflammatory cells and vessels, producing ___________. This _________ provides a much firmer anchorage

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granulation tissue, granulation tissue

Front 57

Initially, the attachment of these larger thrombi is mediated by the actions of adhesion molecules, such as fibrin.
With time, the thrombus stimulates the in-growth of inflammatory cells and vessels, producing granulation tissue. This granulation tissue provides a much firmer anchorage.
This process is called “__________”, and the inflammatory cells of this granulation tissue dissolve the thrombus, while the thrombus is replaced by collagen from the granulation tissue.
Occlusive thrombi may also be recanalized, and the blood could flow again through the previously impassable lumen.

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Organization

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If the thrombus cannot be organized and firmly attached or dissolved, it may break off from the anchoring surface, giving rise to _____.

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emboli

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white or red: infarcts are typical of arterial occlusion in solid organs (heart, kidneys, etc).

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white

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white or red infarct: The area of ischemic necrosis caused by the arterial obstruction is typically paler than the surrounding tissue. It is often rimmed by a thin red zone containing extravasated blood that was destined to reach the ischemic zone from surrounded anastomotic blood vessels.

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white

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red or white infarct: typical of venous obstruction involving the intestines or testes. The venous circulation may be interrupted as a result of twisting of the organ around its supporting structure.

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red

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red or white infarct:Twisting of the sigmoid colon (volvulus) causes compression of the blood vessels in the mesentery. As the veins have thin walls, they are compressed much more easily than arteries. This leads to a sudden onset of venous congestion, local ischemia, and necrosis.

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red

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red or white infarcts: typical of organs that have a dual blood supply, such as the liver or lungs.

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red

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Necrotic brain cells cannot be replaced by regeneration either but fibrous scars do not form. The liquefied brain tissue is ultimately resorbed, leaving behind a cyst filled with clear fluid, that later undergoes _________

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gliosis

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Infarcts caused by infected thrombi or emboli (septic infarcts) show signs of inflammation and may transform into an _________ that tends to heal poorly because of an inadequate blood supply to the infarcted area.

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abscess

Front 66

A state of hypoperfusion of tissues with blood, caused by one of three mechanisms:

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1. Pump failure of the heart (Cardiogenic Shock)
2. Loss of fluid from the circulation (Hypo-volemic Shock)
3. Severe gram negative bacteremia (Septic Shock

Front 67

Results from pump failure of the heart, most often secondary to an infarction that destroys a large part of the functioning myocardium. The loss of contractile elements decreases the ability of the heart to pump blood, leading to an arrhythmia.
Similar consequences may result from myocarditis, valvular heart disease or CHF.

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cardoigenic shock

Front 68

Results from a loss of circulatory volume, attributed to massive hemorrhage or to water loss related to a massive burn, vomiting, or diarrhea.

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hypovolemic shock

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results from a loss of vasc-ular tone and pooling of blood in dilated peripheral blood vessels. This occurs in pt’s with anaphylactic shock caused by exposure to an allergen (bee sting) or neurogenic stimuli (pain caused by trauma or spinal cord injury).

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hypovolemic shock

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___________________ shock resulting from the spread of bacteria from a severe localized infection into the blood stream (ie abscesses, pneumonia, or peritonitis)
Can also occur with gram-positive and fungal infections.
Currently the most common cause of death in ICU’s (>100,000/ year).

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Gram-negative endotoxic

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Caused by endotoxin-producing gram-negative bacteria such as E.coli, Proteus, Serratia, Pseudomonas, K. pneumoniae, and the anaerobe Bacteroides.

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septic shock

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these are bacterial cell wall Lipopoly-saccahrides (LPS) in gram-negative bacteria, that forms a complex with LPS binding protein in the serum. This complex binds to receptors on WBC’s and tissue cells, causing release of inflammatory mediators.

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endotoxins

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an initial phase during which reflex compensatory mechanism are activated and perfusion of vital organs is maintained.

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1. Nonprogressive Stage:

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The cardiac failure and the resultant hypo-perfusion are initially compensated for by peripheral vasoconstriction. This redirects blood to vital organs such as the brain and preserves their critical function.

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1. Nonprogressive Stage:

Front 75

Central pooling of blood in the abdominal organs and the lungs is accompanied by pallor of the skin, which also is clammy.
Vasoconstriction of the renal blood vessels results in renal hypoperfusion and a decreased GFR. This activates the RAS for conservation of fluid, increasing the cardiac output and blood pressure. The early stage is reversible and treatable.

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1. Nonprogressive Stage:

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Characterized by tissue hypoperfusion and the onset of worsening circulatory and metabolic imbalances (acidosis).
Results in widespread tissue hypoxia and impairment of intracellular aerobic respiration by which anaerobic respiration follows, resulting in lactic acidosis.

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progressive stage of shock

Front 77

low pH dilates the arterioles and blood begins to pool in the microcirculation, which worsens the cardiac output.
Metabolic acidosis also has a depressive effect on the heart, further potentiating pump failure. Left ventricular insufficiency raises the intrapulmonary venous pressure, causing stagnation of blood in the pulmonary circula-tion, and favors the formation of pulmonary edema and ARDS (shock lungs).

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progressive stage of shock

Front 78

In the lungs, the capillaries are congested and leaky owing to anoxia. The alveolar capillaries necrotize and slough off, and are covered and lined by _______

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fibrin (hyaline membranes)

Front 79

what begins to fall, marking the transition between the reversible and non-reversible stage three. This is due to marked constriction of the renal cortical vessels reducing the GFR with decreased renal output.

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urinary output

Front 80

Sets in after the body has incurred cellular and tissue injury so severe that even if treatment is instituted, survival is not possible.

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Irreversible Stage of Shock

Front 81

The cellular injury is widespread, affecting all organs, the kidneys being the most serious with renal shutdown. The intestines exhibit necrosis, perforation, and peritonitis.

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Irreversible Stage of Shock

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The brain exhibits ischemic encephalopathy, confusion and coma.
Typically, patients are in great distress or are unconscious.
There is marked hypotension, respiratory distress, acidosis, and anuria.
Multiple organ failure is usually present and DIC is common.

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Irreversible Stage of Shock

Front 83

is massive, usually bilateral, hemorrhage into the adrenal glands caused by fulminant meningococcemia. WFS is characterised by overwhelming bacterial infection, rapidly progressive hypotension leading to shock, disseminated intravascular coagulation (DIC) with widespread purpura, particularly of the skin, and rapidly developing adrenocortical insufficiency associated with massive bilateral adrenal

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Waterhouse-Friderichsen syndrome (WFS)

Front 84

On gross examination, the body is usually edematous (_________), and the body cavities contain fluid (effusions and ascites).
On internal examination, the organs appear congested and wet from edema, most prominent in the lungs (2-3 x’s normal wt).
The liver is congested and enlarged, with blood oozing from the cut surface.

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pathology of shock: anasarca

Front 85

The intestines are ____ due to pooling of blood in their vessels, and the walls are swollen from the edema.
The kidneys are swollen with a pale cortex on cut surface, due to the constriction of the cortical blood vessels with cortical-tubular necrosis.
The brain is edematous with flattening of the gyri.

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pathology of shock, dark