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Patho Exam 4: Oxygenation, Perfusion and Infection (Dianne's PPT)
Terms in this set (88)
For the body to function normally we need;
adequate functional vascular bed
is toward the cord
is away from the cord
Sympathetic nervous system
primary integrator of the neurohumoral vasoconstrictor response to arterial under filling.
Activation of renin sympathetic nerves stimulates
the release of vasopressin causing peripheral and renal vasoconstriction.
constricts blood vessels and stimulates the release of aldosterone (adrenal glands) causing increased NA reabsorption.
Sepsis is the leading cause of death in __________________ ____________ _______ ________ and the ________________ leading cause of death in the us overall.
non-coronary intensive care units, eleventh
When the demand for oxygen by the cells in a tissue changes...
it is important to be able to have a corresponding change in the oxygen supply so that there is an efficient distribution of oxygen.
Where does oxygen exchange take place?
The microcirculation is where the exchange takes place.
Inadequate blood flow to the organs and tissues causes..
hypoxia and multiorgan failure
Hypoxia also alerts body tissue damage...... Inflammation Defenses
1. Increase vascular permeability
2. Blood vessels dilate
3. Migration of white cells to injury site (Phagocytes and neutrophils) further increase of fluid to the area.
Inflammatory chemicals, such as histamine, prostacyclin, and kinins, are...
Norepinephrine and epinephrine
promote an increase in cardiac output and generalized vasoconstriction when acting on alpha receptors (will promote vasodilation at beta receptors, which are present in skeletal and cardiac muscle).
Atrial natriuretic peptide
promotes vasoconstriction and water conservation by the kidneys, resulting in an increase in blood volume.
acts as a vasoconstrictor, as well as promoting the release of aldosterone and antidiuretic hormone.
is produced in response to high blood flow or other signaling molecules, and promotes systemic and localized vasodilation.
a life-threatening condition that occurs when the body is not getting enough blood flow. Lack of blood flow means that the cells and organs do not get enough oxygen and nutrients to function properly. Many organs can be damaged as a result. Shock requires immediate treatment and can get worse very rapidly..
Systemic imbalance between oxygen supply and demand
Inadequate blood flow to organs, tissues
Life-threatening cellular dysfunction
Homeostatic regulation --> components
Shock --> one or more components disrupted
is the amount of blood ejected by the left ventricle in one contraction. Although stroke volume can refer to either left or right side of the heart, it is most associated with the left side. It is measured in ml/beat and generally has a normal value of about 1 cc/kg.
is the amount of blood pumped by the heart per minute. Necessarily, the cardiac output is the product of the heart rate, which is the number of beats per minute, and the stroke volume, which is amount pumped per beat. CO = HR X SV. The cardiac output is usually expressed in liters/minute.
MAP, mean arterial pressure
is defined as the average pressure in a patient's arteries during one cardiac cycle. It is considered a better indicator of perfusion to vital organs than systolic blood pressure (SBP).
is the difference between the systolic and diastolic pressure readings. It is measured in millimeters of mercury (mmHg). It represents the force that the heart generates each time it contracts. If resting blood pressure is (systolic-diastolic) 120-80 millimeters of mercury (mmHg), pulse pressure is 40.
Early indicator of shock
Pulse pressure (Narrowing in cardiogenic and hypovolemia. Widening in septic shock)
What maintains muscle surrounding arteries, arterioles in sympathetic tone?
Pathophysiology and Etiology
Hemodynamic properties altered
Tissue perfusion inadequate
Triggered by sustained drop in MAP
Unresolved low blood flow. Poor tissue perfusion and inadequate oxygen delivery eventually causes
Common portals of entry are;
Urinary system; catheters, supra pubic catheters and cystoscopy
Respiratory system; suctioning, aspiration, tracheostomy, ET tubes
Gastrointestinal system; peptic ulcers, ruptured appendix, peritonitis, Septic shock from abdominal infections has a >72% mortality rate.
Integumentary system; surgical wounds, IV catheters, arterial catheters, invasive lines, decubitus ulcers, burns and trauma
Female reproductive system; elective surgical abortions, ascending infections from bacterial post delivery, tampons, and sexually transmitted infections.
Systemic inflammatory response to an insult (infection, injury, ischemia, infarct)
Inflammatory cells are activated causing the release of mediators, damage to endothelium, and hyper metabolism.
Vasodilatation and capillary permeability
Phagocytation of foreign debris occurs and the coagulation cascade is activated
Alert body tissue damage...... Inflammation Defenses
Blood vessels dilate
Increase vascular permeability
Migration of white cells to injury site (Phagocytes and neutrophils) further increase of fluid to the area.
Stage I: Early, Reversible, and Compensatory Shock
Baroreceptors detect sustained drop in MAP
SNS increases heart rate
Compensatory shock after MAP falls
MAP falls 10-15 mmHg below normal levels
Compensatory mechanisms short-acting
The SNS in Stage I
The SNS increases heart rate, and the force of cardiac contraction = increasing cardiac output, SNS increases peripheral vasoconstriction, increased systemic vascular resistance and an increase in arterial pressure.
Stimulation of the SNS results in the release of epinephrine from the adrenal medulla and the release of norepinephrine, both hormones stimulate the alpha and beta adrenergic fibers, this causes vasoconstriction in skin and visceral organs
Stimulated beta receptors cause vasodilatation in vessels supplying the heart and skeletal muscles and increase the heart rate and force of contractions. Beta 2 dilates respiratory system and increases respiratory rate.
Alpha-receptors are located on the arteries. When the alpha receptor is stimulated by epinephrine or norepinephrine, the arteries constrict. This increases the blood pressure and the blood flow returning to the heart. The blood vessels in skeletal muscles lack alpha-receptors because they need to stay open to utilize the increased blood pumped by the heart.
response occurs as the blood flow to the kidneys is reduced. Converted to Angiotensin 2 causing vasoconstriction and stimulates the adrenal cortex to release aldosterone, holding on to sodium and water. And lose potassium
causes the adrenal glands to release aldosterone, hanging on to sodium and water helps save volume
The types of sympathetic or adrenergic receptors are...
alpha, beta 1, and beta 2.
Posterior pituitary gland releases
antidiuretic hormone which increases renal reabsorption of water as well
15 - 30% loss of vascular fluid will result in...
sympathetic nervous system response. Hyper metabolic state.............Increase heart rate, Increase cardiac output, Increase respiratory rate, decreased urine output.....................................................If corrected with crystalloids for fluid replacement tissue dysfunction is reversible.
Compensatory mechanism: fluid shifts from
the interstitial space into the capillaries, raising volume
Stage II: Immediate or Progressive Shock
After sustained decrease MAP of 20 mmHg
Lactic acid formation
Sodium-potassium pump failure
Heart rate, vasoconstriction increase
Perfusion of organs decreases
Cells in heart, brain hypoxic
Generalized acidosis and hyperkalemia
Fluid loss of 35-50%
Aerobic to anaerobic metabolism
Anaerobic contributes to..
Adenosine triphosphate the source of energy for the cells is..
No longer effictive
The sodium potassium pump fails...
the cell swells and cell membrane integrity is lost, lysosomes spill out and destroy cells. DIC develops.
If cells are deprived of oxygen, instead of using aerobic (with oxygen) metabolism to function, the cells use the..
anaerobic (without oxygen) pathway to produce energy.
By product of anaerobic metabolism
With a persistent oxygen debt and overwhelming of the body's buffering abilities..
lactic acidosis ensues
What is lactic acid used for in the body?
lactic acid is the normal endpoint of the anaerobic breakdown of glucose in the tissues. The lactate exits the cells and is transported to the liver, where it is oxidized back to glucose. In the setting of decreased tissue oxygenation, lactic acid is produced as the anaerobic cycle is utilized for energy production
Stage III: Refractory or Irreversible Shock
Generalized tissue anoxia
No treatment can reverse damage
This stage begins as the compensatory mechanisms fail.
Circulating volume is depleted.
Profound hypotension and hypoxemia
Multisystem organ failure
Recovery is very unlikely
Third spacing, Anasarca
Capillary permeability increases, allowing fluid and proteins to leak from the intravascular space into the interstitial space
Classifications of shock
LOW BLOOD FLOW
- Tumors obstructing flow through the
superior and inferior vena cava
MALDISTRIBUTION OF BLOOD FLOW
Causes of shock
Heart's pumping ability compromised. Pump problem mechanical cardiac dysfunction leading to an acute and significant decrease in cardiac output. Decrease in CO leads to decreased in MAP. Causes include - Dysrhythmias, Cardiomyopathy, Structural Problems. The goal is to reduce the work load of the heart and to repair the heart to assist with forward flow through mechanical intervention.
MI, CDMY.... Inability to pump forward
affects the right side of the heart.............pulmonary circulation compromised.
Inadequate filling...... decreased cardiac output
Is the most common type of shock, present with trauma and acute blood loss. Decrease in intravascular volume = or > 15%. Decreased in blood to heart. Causes include - Severe trauma with massive tissue injury, Third Spacing.
Compression of Superior or Inferior Vena Cava, Pulmonary embolism (Obstruction in heart, great vessels)
Wide spread vasodilatation and encompasses septic, anaphylactic and neurogenic shock. Other causes - Pancreatitis, infection, (Bacterial - Fungal - Viral)
is defined as suspected or microbiologically proven infection together with SIRS.
Spinal cord injury, Opioid overdose. Impaired tissue perfusion resulting from damage or dysfunction of the sympathetic nervous system.
Imbalance between parasympathetic and sympathetic stimulation of vascular smooth muscle --> sustained vasodilation. Dramatic reduction in systemic PVR.
This type of shock is uncommon, and may be associated with trauma, anesthesia, spinal shock. Occurs following spinal cord injury at T5 or above. Hemodynamics phenomenon can occur.
Hyper sensitivity to a sensitizing substance. Immediate massive vasodilatation occurs. Immune response.... vasoactive mediators... increased capillary permeability with fluid in the interstitial space. Impaired tissue perfusion resulting from antigen-antibody reaction releasing histamine into the bloodstream. May be caused by contrast media, drugs, blood transfusions, food allergies, insect stings, snake bites. Capillary permeability increases, arteriolar dilation occurs. Blood return to the heart decreases dramatically
Was defined as sepsis-induced hypotension persisting despite adequate fluid resuscitation.
Leading cause of death in client in ICUs.
Part of progressive syndrome (Systemic inflammatory response syndrome).
Causes include: infection, (Bacterial - Fungal - Viral)
Effects of Shock on Body Systems
Cardiovascular- hypoxia, hyperkalemia, damaged electrical system, decreased cardiac output
Respiratory- impaired alveoli, decreased exchange, decreased oxygenated blood, increased carbon dioxide levels.
Gastrointestinal- ischemic, ulcerated mucosa, paralytic ileus occurs
Neurological- cerebral hypoxia, restlessness, cerebral edema, loss of sympathetic tone
Renal system- hypoperfusion, decrease in GFR
Skin, Temp and Thirst - cold, clammy skin; decreased body temp; increased thirst
SIRS - Widespread endothelial injury and dysfunction, Vasodilation and increased capillary permeability
Mediator excess: cytokines (tumor necrosis factor, interleukins), oxygen free radicals, etc.
Neutrophils entrapment in microcirculation
Hemodynamic phenomenon can occur within thirty minutes of a spinal cord injury. Occurs at T5 or above.
Massive vasodilatation without compensation R/T Sympathetic vasoconstrictor tone lacking. Blood pooling in vessels...tissue perfusion ends and impaired cellular metabolism.
DIC in Sepsis
DIC is a potential risk associated with sepsis, it is characterized by simultaneous bleeding and clotting throughout the vasculature. Sepsis injures blood cells causing platelet aggregation and decreased blood flow, blood clots form through out the microcirculation. The clotting slows circulation while stimulating excess fibrinolysis. As the body's stores of clotting factors are depleted generalized bleeding occurs.
is the clinical name for blood poisoning by bacteria. Septicemia that progresses to septic shock has a death rate as high as 50 percent, depending on the type of organism involved. Septicemia is a medical emergency and needs urgent medical treatment. Most likely cause staphylococcus and streptococcus bacteria
takes on temperature of environment.
Failure of more than one organ (system) in an acutely ill patient
Primary: occurs early, result of well defined illness or injury
Secondary: result of uncontrolled systemic inflammation with resultant organ dysfunction.
1. Activation of the inflammatory cells mediator release
2. Damage to endothelium
3. Excessive vasodilation.....decrease SVR and hypo tension
4. Increase vascular permeability.......fluid interstital space
5. WBC results in phagocytosis activating the coagulation cascade.
Acute Respiratory Failure
May develop suddenly or gradually
May rapidly become life-threatening
ARF's is an inability of lungs to meet O2 demands of tissues
Greatest risk of death occurs if ARF co-exists with cardiac problems, anemia and or shock states
Exists when exchange of oxygen for carbon dioxide in the lungs cannot keep up with the rate of O2 consumption and CO2 production by cells of the body
the concentration of hydrogen in arterial blood.
reflect the metabolic demands of the tissue
reflect the partial pressure of the gas in the alveoli.
Hypoxemic Respiratory Failure
PaO2 of 60 mmHg or less when patient receiving supplemental O2 concentration of 60% or greater
Causes: Any disorder that interferes with O2 transfer into blood and low cardiac output states
(Primary cause is sepsis. Other causes - Pneumonia, pulmonary edema, PE, smoke inhalation, ventilator-induced lung injury. Heart failure, shock)
refers to the ease with which the lungs can be inflated
Elastin and collagen fibers................Elastin fibers stretch and increase lung inflation...........Collagen fibers resist stretching
Pulmonary blood vessels and hypoxia
Blood vessels in the pulmonary circulation under go marked vasoconstriction when exposed to hypoxia.
Prolonged hypoxia can lead to pulmonary HTN, Increase R sided heart workload
PAO2 in Hypoxemic Respiratory Failure
PAO2 decreases despite increase in O2 supplement
Mediators cause changes in lungs
Increased pulmonary capillary membrane permeability
Destruction of elastin and collagen
Formation of pulmonary micro emboli
Pulmonary artery vasoconstriction
In ARDS pain and hypoxia cause...
systemic vasoconstriction and activates the stress response. Increase in O2 consumption and increase in CO2 production.
Surface tension in the alveoli is required for...
lines the inner surface of the alveoli ..................surfactant decreases surface tension and provides stability.
Pulmonary artery vasoconstriction
Pulmonary artery vasoconstriction is thought to serve as an adaptive mechanism for diverting blood flow from poorly ventilated to better-ventilated regions of the lung to improve ventilation
Initiation of ARDS
Alveolar collapse (Decreased compliance, Atelectasis, Fluid filled alveoli interfere with gas exchange, Blood PaO2 levels fall)
Fibrin and cell debris form hyaline membrane
When macrophages and neutrophils adhere to endothelial surfaces of the alveoli and capillaries...
They release oxidants, inflammatory mediators enzymes, and peptides that damage the capillary and alveolar walls.
Damaged capillary and alveolar walls become permeable allowing plasma, proteins, and erythrocytes to enter the interstitial space. As interstitial edema increases, and fluid leaks into alveoli. An imbalance occurs between the osmotic force that pulls fluid from the interstitial space into the capillaries and the normal hydrostatic pressure that pushes fluid out of the capillaries causing more fluid to accumulate.
Protein rich fluid __________ surfactant
Surfactant is lost and the alveoli stiffen and collapse, atelectasis, increased breathing effort.
This ion transport system moves sodium ions out of the cell and brings potassium ions into the cell. This transport function is necessary for cell survival because sodium diffusion into the cell and potassium diffusion out of the cell down their concentration gradients would reduce their concentration differences (gradients) across the cell membrane over time. Loss of these ion gradients would lead to cellular depolarization and loss of the negative membrane potential that is required for normal cell function
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