Transcript Septic Shock

Chapter 20
Heart Failure and
Circulatory Shock
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Types of Heart Failure
• High-output versus low-output failure
– Is cardiac output high or low?
• Systolic or diastolic failure
– Is the heart failing to pump out enough blood, or
failing to accept enough blood from the body and
lungs?
• Right-sided or left-sided failure
– Is the right or left side of the heart failing?
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Manifestations of Heart Failure
• Effects of impaired pumping
• Effects of decreased renal blood flow  RAA pathway
• Effects of the sympathetic nervous system
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Scenario:
• Mr. M has heart failure and he complains of severe
shortness of breath, and has fluid in his lungs. He
has tachycardia, increased diastolic blood pressure,
pale moist skin, and says he feels weak, dizzy, and
anxious all the time.
Question:
• Which of these signs and symptoms are due to
decreased renal blood flow?
• Which are due to the sympathetic nervous system?
• Which side of his heart do you think is failing?
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Left-Sided Heart Failure
body
Body lacks blood
right
heart
Systolic: LV does
not pump enough
blood to body
left
heart
Lungs fill with fluid
lungs
Diastolic: LV does
not accept enough
blood from lungs
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Right-Sided Heart Failure
Diastolic: RV does
not accept enough
blood from body
body
Body fills with blood
right
heart
Systolic: RV does
not pump enough
blood to lungs
Lungs do not
oxygenate enough blood
lungs
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left
heart
Pulmonary Edema
• Capillary fluid moves into alveoli
– Lung becomes stiffer
– Harder to inhale
– Less gas exchange in alveoli
– Crackles
– Frothy pink sputum
• Hemoglobin not completely oxygenated
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Question
Tell whether the following statement is true or false:
The characteristic pink sputum produced is pulmonary
edema is tinged with blood.
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Answer
True
In pulmonary edema, the alveolar capillary membrane is
damaged, and blood from the capillaries moves into the
alveoli. The blood from the capillaries causes the sputum
(produced from the lower respiratory tract) to appear
pink or light red.
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Cardiogenic Shock
• Heart fails to pump blood adequately
– Decreased cardiac output lowers BP
– Sympathetic system responds
– Vasoconstriction increases resistance to blood flow
– Increased workload on heart worsens heart failure
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Types of Shock
• Cardiogenic
• Hypovolemic
• Obstructive
• Distributive
• Septic
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Blood Pressure
BP = CO x PR
• Which of the following affect CO, and which affect PR? Why?
–
Blood volume
–
Heart rate
–
Vasoconstriction
–
Angiotensin II
–
Aldosterone
–
Epinephrine
–
Histamine
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Scenario:
• Mr. M was injured in a motorcycle accident.
• On his arrival at the hospital he presented with
bleeding from the right leg, restlessness, pallor,
sweating, elevated heart rate, weak pulse, rapid
breathing, and lack of bowel sounds; his blood pressure
was slightly elevated
Question:
• What has happened to this patient’s:
– Stroke volume
– Cardiac output
–
Sympathetic nervous system
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Scenario (cont.)
• Although he was given 6 units of blood, Mr. M got
worse
• He became lethargic and his blood pressure began
to fall; he still had no bowel sounds or urine
production
Question:
• The intern ordered epinephrine, and Mr. M’s blood
pressure increased. Why?
• Later, you overhear the resident telling the intern
that was not the best treatment. Why not, if it raised
Mr. M’s blood pressure?
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Scenario (cont.)
• Mr. M’s blood pressure went up a bit
• He has been moved out of the ICU
Question:
• His chart says you should do a 24-hour urine
collection. Why?
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Scenario (cont.)
• Mr. M appears to be improving
• He sleeps quite a lot, but his blood pressure has remained
stable; he had a little urine production; and he did not eat
his supper
• Checking on him in the evening, you notice that he is
slightly flushed, his respiration rate is a little high, and his
temperature is elevated
Question:
• What is happening to his peripheral resistance?
• What do you expect his heart rate to be like? Why?
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Distributive or Vasodilatory Shock
• Blood vessels dilate
• There is not enough blood to fill the circulatory
system
• Blood flow decreases
• Less blood is returned to the heart
• Less blood is circulated to the body
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Question
Which type of shock is caused by low blood volume?
a. Cardiogenic
b. Hypovolemic
c. Distributive
d. Septic
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Answer
b. Hypovolemic
Hypo (low) volemia (blood volume) occurs when a patient
has lost blood due to trauma, surgery, or third space
fluid loss.
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Causes of Distributive Shock
• Decreased sympathetic activity: neurogenic
– Brain or spine injury; anesthetics; insulin
shock; emotion
• Vasodilator substances in blood
– Type I hypersensitivity (anaphylactic shock)
– Inflammatory response to infection (sepsis)
• Vessel damage from severe hypovolemia
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Anaphylaxis
• Systemic response to the inflammatory mediators
released in type I hypersensitivity
– Histamine, acetylcholine, kinins, leukotrienes, and
prostaglandins all cause vasodilation
º What will happen when arterioles vasodilate
throughout the body?
– Acetylcholine, kinins, leukotrienes, and
prostaglandins all can cause bronchoconstriction
º What will happen when the bronchioles constrict?
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Sepsis or Systemic Inflammatory
Response Syndrome (SIRS)
• Inflammatory mediators released into the circulation
– Tumor necrosis factor
– Interleukins
– Prostaglandins
• Cause systemic signs of inflammation
– Fever and increased respiration, respiratory
alkalosis, vasodilation, warm flushed skin
• Activate inflammatory pathways
– Coagulation, complement
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Sepsis or Systemic Inflammatory
Response Syndrome (SIRS) (cont.)
Discussion:
• Why is septic shock called distributive?
• In the later phases of septic shock, blood volume
decreases. What part of the inflammatory
process explains this?
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Septic Shock
vasodilation
decreased
peripheral
resistance
decreased
blood pressure
SEPTIC SHOCK
40% mortality
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Septic Shock
• Also called systemic
inflammatory
response syndrome
(SIRS)
• Inflammatory mediators
also increase the
metabolic rate of
tissues, so they need
more oxygen
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Septic Shock (cont.)
“Despite the prompt implementation of
appropriate antibiotic therapy, sepsis
mortality remains high, in the range
of 28% to 50%.”
(Aird, W. C. [2003.] The role of the endothelium in severe sepsis and multiple organ
dysfunction syndrome. Blood 101[10],3765-3777. Retrieved February 10, 2004, from
http://www.blood journal.org/cgi/content/full/101/10/3765.0)
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Septic Shock (cont.)
“Second, patients with culture-positive
and culture-negative sepsis or septic
shock have comparable mortality
rates.”
(Aird, W. C. [2003.] The role of the endothelium in severe sepsis and multiple organ
dysfunction syndrome. Blood 101[10],3765-3777. Retrieved February 10, 2004, from
http://www.blood journal.org/cgi/content/full/101/10/3765.0).
.
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Septic Shock (cont.)
“Third, administration of antiendotoxin antibodies in large,
clinical trials did not improve
survival.”
(Aird, W. C. [2003.] The role of the endothelium in severe sepsis and multiple organ
dysfunction syndrome. Blood 101[10],3765-3777. Retrieved February 10, 2004, from
http://www.blood journal.org/cgi/content/full/101/10/3765.0)
Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins
Question
Which type of shock is the result of a severe allergic
reaction?
a. Cardiogenic
b. Obstructive
c. Anaphylactic
d. Septic
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Answer
c. Anaphylactic
Anaphylactic shock is caused when inflammatory mediators
are released (type I hypersensitivity reaction). The
mediators include histamine, acetylcholine, kinins,
leukotrienes, and prostaglandins, all of which cause
vasodilation.
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Activated Protein C
• Drotrecogin alpha
• Blocks clotting
• Blocks inflammation
• Increases survival of the most seriously ill
sepsis patients
• May cause bleeding!
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Complications of Shock
Scenario:
• A doctor has been called in to treat Mr. M and
has started him on fluid and antibiotics
• You are warned to watch him carefully for any
signs of respiratory distress
Question:
• Why would blood pressure imbalances cause
respiratory distress?
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Complications of Shock (cont.)
• Acute respiratory distress syndrome
• Acute renal failure
• Gastrointestinal complications
• Disseminated intravascular coagulation
• Multiple organ dysfunction syndrome
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Acute Respiratory Distress Syndrome
(ARDS)
• Exudate enters alveoli
– Blocks gas exchange
– Makes inhaling more difficult
• Neutrophils enter alveoli
– Release inflammatory mediators
– Release proteolytic enzymes
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Acute Renal Failure (ARF)
• Renal vasoconstriction cuts off urine production
– Acute renal failure
• Continued vasoconstriction cuts off renal
oxygen supply
• Renal tubular cells die
– Acute tubular necrosis
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Disseminated
Intravascular
Coagulation
(DIC)
coagulation
pathways
activated
clots in
many
small
blood
vessels
platelets
and
clotting
proteins
used up
microinfarcts,
ischemia
bleeding
problems
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Multiple Organ Dysfunction Syndrome
(MODS)
• The most frequent cause of death in the
noncoronary intensive care unit
• Mortality rates vary from 30% to 100%
• Mechanism not known
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Question
Tell whether the following statement is true or false:
Treatment for ARDS often includes breathing assistance
using mechanical ventilation.
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Answer
True
Because alveoli are filled with exudate and blood that has
leaked from the capillary, the surface area available for
gas exchange is greatly reduced. Most patients will
require ventilatory support until the process reverses.
ARDS has a high mortality rate because it is difficult to
ventilate these patients.
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