Fluid And Hemodynamic Derangements Flashcards
excessive quantities of fluid that accumulate (typically) in the intercellular spaces
Edema
an “escape” of fluid into tissues or a structure
(as in movement of fluids from blood vessels into tissue
spaces or compartments)
Effusion (efflux)
TYpe of edema fluid that is a protein-poor fluid
consisting of water and electrolytes
Transudate
Type of edema fluid that is Protein-containing and results from leaky
(permeable) vessels
Exudate
Starlings hypothesis states that the direction and rate of movement of fluids between blood and the tissue spaces are influenced by:
- Hydrostatic and osmotic pressures of blood
- Hydrostatic and osmotic pressures of interstitial
fluids - The properties of the vessel wall (filtering
membrane)
The pathogenesis of edema occurs when there are alterations to Starling’s forces such as:
- Increased hydrostatic pressure of venules and
capillary beds, contributing causes include venous obstruction and pooling - Decreased oncotic (osmotic) pressure of plasma, Associated with hypoproteinemia
- Increased vacular (endothelial) permeability - causes include injury, inflammation, hypoxia, some forms of shock etc.
Lymph obstructions can also cause edema. Where are some causes of lymph obstruction?
- tumors
- inflammation and scarring
- elephantiasis
Excess peritoneal fluids
Ascites (hydroperitoneum)
Causes of ascites
Causes include chronic liver disease (most
common), CHF, and disseminated abdominal cancer
Excess pleural fluids
Hydrothorax (pleural effusion)
Causes of Hydrothorax (pleural effusion):
causes include “left side”
heart failure and obstruction of thoracic veins
severe generalized edema
Anasarca
Causes of anasarca:
contributing causes
include chronic congestive heart failure and renal disease
associated with subcutaneous edema,
applying pressure to the skin drives fluid out leaving a “dimple”
Pitting edema
fluids collect in “dependent region” of
body (ankle edema, etc.)
Dependent edema
What are local factor that contribute to edema?
- venous obstruction
- increased vascular permeability
- lymphedema
What are some systemic factors that contribute to edema?
- congestive heart failure
- hypoproteinemia
What are some common causes of venous obstruction that contributes to edema?
thrombi, tumors, poor posture,
tight garments, etc.
What are some possible causes of increased vascular permeability that would lead to edema?
inflammation,
vascular hypoxia, prolonged cold (“immersion foot)
HOw does congestive heart failure contribute to edema?
contributes to elevated
systemic venous pressure and reduced renal perfusion (renal hypoxia) with increased fluid retention
How does liver disease contribute to edema?
Liver disease leads to decreased synthesis of plasma proteins (hypoproteinemia) and fluid loss by osmosis
How does renal disease contribute to edema?
Can give rise to proteinuria and hypoalbuminemia when then leads to hypoproteinemia and fluid loss by osmosis
Is edema a disease?
No, it is a sign of disease
Organ edema with potential life threatening effects:
- Pulmonary edema- alveolar spaces fill with fluid
- Hydrothorax (pleural effusion) and
hydropericardium may compress lungs or heart - cerebral edema - Swelling leads to compression and distortion of affected regions
localized excess of blood, engorgement
Hyperemia
Factors contributing to hyperemia
- increased arterial blood flow (“active
hyperemia”) - impaired venous drainage (“passive hyperemia”)
What causes passive hyperemia?
Impaired venous drainage and decreased outflow of blood from affected region; causes include heart failure, venous obstruction, etc.
What causes active hyperemia?
Increased arterial blood flow from exercise (increased blood flow in skeletal muscle) acute inflammation, temperature regulation, cutaneous blushing and responses to temporary interruption of blood supply. This type is regulated by neurogenic and hormonal influences
What kind of hyperemia is characterized by local redness and increased warmth?
Active hyperemia
What kind of hyperemia is characterized by cyanosis and edema?
Passive hyperemia because there is decreased outflow of blood from affected region
What is the effect of passive hyperemia in the lungs?
- Pulmonary capillaries become engorged and leak fluid and blood cells
- Hemosiderin containing macrophages accumulate and cause pulmonary fibrosis
What is the effect of passive hyperemia on the liver?
Centrilobular venous congestion leads to “nutmeg” liver (brown spots on pale background) and can eventually cause cirrhosis or necrosis. This can be due to CHF or obstruction of the hepatic veins/inferior vena cava
What is the effect of passive hyperemia on the spleen?
Portal venous congestion and hypertension will lead to distention of the spleen (splen omega LH) and engorgement of splenic sinuses
discharge of blood from vessels into surrounding tissues (“extravasation” of blood)
Hemorrhage
Loss of 20% of blood due to hemorrhage will result in:
Feeling sick
Loss of 40% of blood due to hemorrhage will result in:
Risk of hypovolemic shock
Chronic hemorrhage in which someone sustains losses of few ml/day of blood could give rise to ____.
Anemia
Discharge of blood from vessels to environment
External hemorrhage
Discharge of blood from vessels to tissue
Internal hemorrhage
What are the effects of internal hemorrhage on organs?
- compression
- destruction
- disruption of blood supply
What are common causes of internal hemorrhage?
- coagulation disturbances
- platelet dysfunction
- congestion
- shock
- vasculitis due to infection or hypersensitivity
Small, “pin-point” hemorrhages (1-2 mm) of epithelial tissues (skin, conjunctiva, mucous membranes, serosa, etc.)
Petechiae
Causes include shock, venous obstruction,
platelet abnormalities, etc.
Medium hemorrhagic patches (3-5
mm of epithelial tissues (skin, conjunctiva, mucous membranes, serosa, etc.)
Purpura
Causes include shock, venous obstruction,
platelet abnormalities, vasculitis, vascular degeneration or coagulation disorders
Large hemorrhagic patches (1-2 cm or more) of epithelial tissues (skin, conjunctiva, mucous membranes, serosa, etc.)
Ecchymosis (bruise)
Accumulation of blood in tissues that creates a
“mass”; in some instances, adjacent structures may be compressed
Hematoma
may affect local
blood flow and delay healing.
Bleeding into peritoneum
Hemoperitoneum
Bleeding in pleural spaces
Hemothorax
Bleeding into pericardium
Hemopericardium
Bleeding into joint space
Hemarthrosis
Respiratory bleeding
Hemoptysis
Bloody vomit
Hematemesis
dark stool due to degraded blood pigment,
associated with bleeding in upper-mid GI tract
Melina
“bright blood” present in stool, due to
bleeding in lower colon, rectum and anal regions
Hematochezia
Causes of vascular obstruction
- External compression: tumors, scar tissue
- Arterial spasms
- Diseases of vessel wall (arteriosclerosis and vasculitis) with narrowing, etc.
4. Thrombi and emboli
Closely regulated processes maintain blood in a fluid state under normal conditions and provide for rapid formation of localized hemostatic plugs at sites of vascular injury.
Hemostasis
a pathological process that leads to the formation of aggregates of coagulated blood within the lumen of blood vessels or heart chambers in a living organism.
Thrombosis
Arterial thrombosis is most commonly caused by:
atherosclerosis and
is a major cause of myocardial infarction, stroke and vascular obstruction of the lower extremities.
Other contributing causes include inflammatory
arteritis, aneurysms, and altered endothelial cell function
a common complication of venous congestion (stasis), inflammation, trauma and hypercoagulability. They are most common in the deep veins of the lower extremities and pelvis
Venous thrombosis
DVT if in the deep veins of the lower extremity
The Symptoms of DVT are variable but these thrombi carry a high risk for ____.
pulmonary embolization.
coagulation of blood “everywhere else” except blood vessels and heart
Blood clots
______ occur within blood vessels and heart
after death and are differentiated from antemortem thrombi.
Postmortem clots
In general, activation of the ____ and ____ promote thrombosis
plasma clotting factors and platelets
actions of the ____ and ____ inhibits this process.
endothelial cells and plasmin
the circulating precursors
(clotting factors) are activated through a series of enzymatic interactions that ultimately give rise to thrombin and the polymerization of fibrinogen to form ____.
Fibrin
hemostasis usually is associated with the _____ pathway of coagulation
intrinsic
activation of the ____ pathway of coagulation is more common with thrombosis.
extrinsic
What functions do platelets have in hemostasis?
- formation of platelet plug
- promote coagulation
- produce thromboxane, ADP, growth factors and other agents
Platelets are activated by exposure to collagen at site of injury and then undergo the following reactions:
- adhesion
- secretion
- aggregation
The _____ provides
molecular bridges between platelet surface receptors and exposed collagen in adhesion that are strong enough to overcome the hemodynamics forces of flowing blood
von Willebrand Factor
Normal vascular endothelial cells exhibit antiplatelet, anticoagulant and fibrinolytic properties but when injured they also exert _____ actions. Ultimately, the balance between these activities determines whether thrombus formation, propagation or degradation occurs.
prothrombic
Antiplatelet effects of normal vascular endothelial cells:
Normal endothelial cells are unreactive to non-activated platelets. These cells also secrete agents that inhibit platelet responses
Anticoagulation effect of normal vascular endothelial cells:
Normal endothelial cells produce heparin-like agents and thrombomodulin which inactivate clotting factors
Fibrinolytic properties of normal vascular endothelial cells
Normal endothelial cells synthesize plasminogen
activator which clears (degrades) fibrin deposits, etc.
Procoagulant/prothrombic activities of injured vascular endothelial cells include:
- Release of thromboplastin which
activates the “extrinsic” pathway - Produce von Willebrand factor (vWF),
- Inhibits plasminogen activator which diminishes fibrinolysis, etc.
- Damage to the endothelium; collagen and other underlying elements are exposure to reactive elements of the blood
Once activated, the thrombosis must be restricted (localized) to the site of origin to prevent coagulation of the entire circulatory system.
Regulatory and thrombolytic factors include the following:
- Activation of serum protease inhibitors
- “depletion” of local platelets and clotting factors
- “Clearance” of activated factors by blood flow
- Endothelial cell functions
- Fibrinolytic mechanisms
Describe the plasminogen system
activated plasmin lyses and removes fibrin clots; it also gives rise to “fibrin split products” which are weak anticoagulants. This is used in regulation of clotting
How do streptokinase help regulate coagulation?
There are derived from certain bacteria and are used to lyse thrombi
What is Virchow’s triad?
Predisposing factors that contribute to formation of thrombi
What are the three predisposing factors of Virchow’s triad that contribute to formation of thrombi?
- endothelial injury and dysfunction
- alterations in blood flow
- hypercoagulation
dominant influence that may singly cause thrombosis:
Endothelial injury and dysfunction
What are examples of endothelial injury and dysfunction that can contribute to formation of thrombi:
- vascular lesions such as atherosclerosis and vasculitis
- Myocardial and valvular disease including cardiac dysfunction, endothelial injury and valve dysfunction
What are examples of alterations in blood flow that could contribute to thrombi formation?
- stasis due to vascular obstruction or immobilization, heart failure or other circulatory deficits
- turbulence from aneurysms, valve lesions or atherosclerotic plaques
Hypercoagulation “states” contribute less frequently to thrombosis but are also important causes; these include:
- Tissue injury (trauma, surgery, burns) release thromboplastins - Obstetrical conditions - Neoplasms - Smoking - Elevated estrogen - Polycythemia and other blood disorders - Factor V mutations and other genetic factors.
Thrombi formed in “moving blood”; are usually firmly attached to vessel wall
Antemortem thrombi
Common locations from antemortem thrombi?
regions predisposed to
atherosclerosis, the heart and veins
What are the classifications of antemortem thrombi?
Arterial (white) thrombi
Venous (red) thrombi
Septic (infected)
Bland (sterile)
What are lines of Zahn?
alternating layers of fibrin and aggregated platelets as seen in arterial thrombi
When are arterial thrombi occlusive and when are they usually non occlusive?
When formed in the aorta or within the heart, these are usually nonocclusive (mural) whereas occlusive thrombi are common in small arteries and in veins
Are venous thrombi usually occlusive or not?
Occlusive
Venous thrombi are usually associated with _____
Stasis
Blood elements not associated to vessel wall that “settle out” and give rise to layer of “chicken fat” and “currant jelly”
Post Morten thrombi
What does the “chicken fat” layer of a postmortem thrombi contain?
Lighter weight “supernatant portion” of platelets and fibrin
What does the “currant jelly ” layer of a postmortem thrombi contain?
heavier elements enriched with RBC that “settle out”
When thrombi enlarge and elongate
Propagation (extension)
Generally, propagation progresses in direction of blood
flow unless blood flow is blocked
action of the fibrinolytic system commonly occurs 24-48 hours after thrombosis, especially in the lungs, and results in
Resolution (lysis)
Thrombosis resulting in obstruction in sites remote to the location of the original thrombus
Embolization
Abnormal masses carried in the blood, includes thrombi, gases,
lipids, amniotic fluid, tissue fragments, etc.
Emboli
99% of emboli are thrombo emboli
What is a paradoxic emboli?
emboli of venous origin enter systemic
arteries through septal defects of heart or other abnormal arterial-venous connections
Air- introduced in blood vessels through trauma
(laceration of veins, chest wall injury), vascular
catheterization, obstetric complications, injection and other procedures
Gas emboli
nitrogen gas-bubbles form in the blood giving rise to pulmonary obstruction- ”chokes”) and in tissue (“bends”- with pain). May be encountered in underwater divers, high altitude flight crews, etc.
Rapid decompression
What occurs with repeated compression/decompression exposure?
gas bubbles may accumulate and obstruct blood vessels in parts of the skeleton (known as “caisson disease”, etc.) and may cause ischemic necrosis of bone (head of femur, tibia and humerus, etc.).
Said to be a ”distant” second to thrombi as a source of emboli
Soft tissue trauma and fracture of long bones contribute to fat and adipose emboli, these are carried through the systemic veins to reach the lungs
disruption of blood supply leading to hypoxia and death (ischemic necrosis) of affected tissue
Infarct
infarcts tend to be “______ -shaped” with the location of occlusion at the apex
wedge
Causes of infarct
any form of cardiovascular inadequacy (CHF, shock, thrombi and emboli and any other interruption of blood flow)
What kind of infarct is most common?
Arterial
Venous is less common except in single venous outlet such as gonads
What is an anemic or ”pale” infarct
Type of infarct common in arterial obstruction of solid organs (heart, kidney spleen)
What are predisposing risk factors for infarct?
- Pre-existing cardiovascular disease
- Low blood oxygen levels (anemia)
- High oxygen requirements of affected tissues
- Poor blood supply at the site of obstruction (collaterals help)
- Acute onset and rapid progression of occlusive event (less time to adapt)
Inadequate perfusion of tissues by blood leads to
Shock
Shock due to loss of fluid
Hypovolemic shock
What are causes of hypovolemic shock
- hemorrhage
- dehydration
- inadequate water intake
- excessive sweating
- GI disturbance
Inadequate perfusion of tissues by blood due to heart failing to pump
Cardiogenic shock
What are some common causes of cardiogenic shock?
severe MI, fibrillation, valve rupture,
cardiac tamponade, large pulmonary embolus
Loss of vasomotor tone (vasodilation) that can lead to shock
Peripheral pooling
-> pooling of blood -> decreased venous return -> decreased cardiac output -> inadequate perfusion of tissues
Neurogenic causes of peripheral pooling that can lead to inadequate perfusion of tissues:
- pain
- deep anesthesia
- brain or spinal cord injury
- vasovagal syncope
Type of shock associated with endotoxins proving bacterial infection
Septic shock
TYpe of shock that is associated with sensitization to an antigen resulting in widespread vasodilation and bronchospasm
Anaphylaxis
Clinical manifestations of shock:
- cold skin (in hypovolemic and cardiogenic shock)
- warm skin (in septic and anaphylactic shock)
- Increased heart rate, weak pulse and sweating are common
- hypoxia contributes to
acidosis (anaerobic glycolysis gives rise to lactic acid) and increased risks for cell injury and death
In early stages of shock ____ mechanism dominate and effects are reversible. Later, ____ may occur if not checked
Compensatory
Progressive shock
What are the compensatory mechanisms for shock”
- activation of SNS reflex for increased HR and peripheral vasoconstriction which helps maintain circulation in central organs but can cause ischemia in peripheral organs
- secretion fo renin and angiotensin which elevates vasomotor tone and increases secretion of aldosterone to increase blood volume
Severe or prolonged shock to the brain will cause:
Diminished CNS function due to “boundary zone” infarcts and global brain ischemia and necrosis
Severe or prolonged shock to the heart will cause:
Greater risk of infarct due to poor oxygenation of blood, plus increased compensatory cardiac work load
Severe or prolonged shock to the kidneys will cause:
renal tubular epithelium is at risk for necrosis during
severe or prolonged shock, this is known as ATN (acute tubular necrosis), which may cause acute renal failure
Severe or prolonged shock to the lungs will cause:
widespread alveolar damage and respiratory failure (“shock lung”) may occur
- the lungs are relatively unaffected by most forms of shock
except septic shock
Generally, all forms of shock may be considered to be reversible
but when advanced or with significant organ damage, shock may begin to ______.
decompensate
What occurs when shock begins to decompensate when advanced and organ damage occurs?
- The compensatory responses are no longer adequate or are reversed
- Progressive vascular injury, damage to the vasomotor center and thrombosis contribute to deterioration and ultimately, irreversible changes
What types of shock have the poorest prognosis?
Cardiogenic and septic
