Cardiogenic Shock Flashcards
What is cardiogenic shock?
Cardiogenic shock occurs when the heart fails to pump blood sufficiently to meet the body’s demands.
What are the key indicators of cardiogenic shock?
Decreased CO, hypotension, hypoperfusion, and indications of tissue hypoxia despite adequate intravascular volume.
What is the most common cause of cardiogenic shock?
Myocardial infarction (MI).
What happens to stroke volume (SV) and cardiac output (CO) in cardiogenic shock?
Both SV and CO decrease, resulting in insufficient perfusion to meet cellular demands.
What mediators contribute to the deterioration of cardiac function in cardiogenic shock?
Norepinephrine, which increases systemic vascular resistance.
What role does preload play in cardiogenic shock?
Preload increases as blood returning to the heart is added to blood that was not pumped forward.
What happens to coronary artery perfusion in cardiogenic shock?
Coronary artery perfusion is impaired due to increased preload and afterload.
What are the clinical manifestations of cardiogenic shock?
Hypoperfusion with hypotension, cyanosis, decreased urine output, neurologic changes, and elevated preload.
What is the primary goal of treatment for cardiogenic shock?
To improve CO, reduce myocardial workload and oxygen needs, and increase coronary perfusion.
Name two pharmacologic treatments for cardiogenic shock.
Vasodilators (e.g., nitroprusside, nitroglycerin) and positive inotropic agents (e.g., dobutamine, milrinone).
What is the function of the intra-aortic balloon pump in treating cardiogenic shock?
Enhances coronary and systemic perfusion while decreasing afterload and myocardial oxygen demands.
What is hypovolemic shock?
Diminished blood volume causing inadequate filling of the vascular compartment.
What percentage of circulating blood volume loss can lead to hypovolemic shock?
An acute loss of 15% to 20%.
What compensatory mechanisms occur in hypovolemic shock?
Sympathetic-mediated responses such as tachycardia, increased cardiac contractility, and vasoconstriction.
What laboratory tests are used to assess hypovolemic shock?
Hemoglobin and hematocrit, serum lactate, arterial pH, and arterial blood gas measurement.
What is the primary treatment goal in hypovolemic shock?
To restore vascular volume.
Name two types of fluids used in the treatment of hypovolemic shock.
Crystalloids (e.g., isotonic saline, Ringer lactate) and plasma volume expanders (e.g., pentastarch, colloidal albumin).
What characterizes distributive shock?
Loss of blood vessel tone, enlargement of the vascular compartment, and displacement of vascular volume away from the heart.
True or False: In hypovolemic shock, urine output decreases very quickly.
True.
Fill in the blank: The most immediate compensatory mechanism in shock is __________.
sympathetic-mediated responses.
What is distributive shock?
Distributive shock is characterized by loss of blood vessel tone, enlargement of the vascular compartment, and displacement of the vascular volume away from the heart and central circulation.
Distributive shock is also referred to as normovolemic shock.
What are the main causes of distributive shock?
The main causes are:
* Decrease in sympathetic control of vasomotor tone
* Release of excessive vasodilator substances
* Complications from vessel damage due to hemorrhage
What are the three shock states that share the basic circulatory pattern of distributive shock?
The three shock states are:
* Neurogenic shock
* Anaphylactic shock
* Septic shock
What causes neurogenic shock?
Neurogenic shock is caused by decreased sympathetic control of blood vessel tone due to defects in the vasomotor center in the brain stem or sympathetic outflow to blood vessels.
What is spinal shock?
Spinal shock describes neurogenic shock that occurs in people with spinal cord injury.
What are common clinical manifestations of neurogenic shock?
Common manifestations include:
* Slower than normal heart rate
* Dry and warm skin
What is anaphylactic shock?
Anaphylactic shock is a severe systemic allergic reaction that results from an immunologically mediated reaction causing the release of vasodilator substances like histamine.
What are frequent causes of anaphylactic shock?
Frequent causes include:
* Reactions to medications (e.g., penicillin)
* Foods (e.g., nuts, shellfish)
* Insect venoms (e.g., bees, wasps)
What are signs and symptoms associated with impending anaphylactic shock?
Signs and symptoms include:
* Abdominal cramps
* Warm or burning sensation of the skin
* Urticaria (hives)
* Coughing, choking, wheezing
What is the primary treatment for anaphylactic shock?
The primary treatment is the administration of epinephrine, which constricts blood vessels and relaxes bronchioles.
What is septic shock?
Septic shock is defined as severe sepsis with hypotension despite fluid resuscitation and is associated with a high risk for mortality.
What is the estimated occurrence of sepsis in the United States?
Sepsis occurs in approximately 1.5 million people each year in the United States, with about 250,000 deaths.
What are the clinical manifestations of sepsis and septic shock?
Manifestations include:
* Hypotension
* Warm, flushed skin
* Abrupt changes in cognition
* Fever and increased leukocytes
What is the primary focus of treatment for sepsis?
The primary focus is on controlling the causative agent and supporting circulation, including early use of antibiotics and aggressive fluid administration.
What does obstructive shock result from?
Obstructive shock results from mechanical obstruction of blood flow through the central circulation.
What is the most frequent cause of obstructive shock?
The most frequent cause of obstructive shock is pulmonary embolism (PE).
What are major complications of severe shock?
Major complications include:
* Pulmonary injury
* Acute renal failure
* GI ulceration
* Disseminated intravascular coagulation (DIC)
* Multiple organ dysfunction syndrome (MODS)
What characterizes Acute Lung Injury/Acute Respiratory Distress Syndrome (ALI/ARDS)?
ALI/ARDS is characterized by rapid onset of profound dyspnea, hypoxemia, and impaired gas exchange.
ARDS is a more severe aspect of ALI.
What is required for the Berlin definition of ARDS?
The following criteria must be present:
* Respiratory symptoms within 1 week of clinical insult
* Bilateral opacities on chest x-ray or CT
* Not solely due to cardiac failure or hypervolemia
* Impairment of oxygenation
What is acute renal failure associated with severe shock?
Acute renal failure is often caused by impaired renal perfusion or direct injury to the kidneys, typically resulting in acute tubular necrosis.
What is an important factor in mortality due to severe shock?
Acute renal failure
Acute renal failure is often caused by impaired renal perfusion or direct injury to the kidneys.
What is the most frequent renal dysfunction seen after severe shock?
Acute tubular necrosis
Acute tubular necrosis is usually reversible but may require weeks or months for normal renal function to return.
How long can a normal kidney tolerate severe ischemia?
15 to 20 minutes
The degree of renal damage is related to the severity and duration of shock.
What monitoring is essential during shock to assess renal blood flow?
Continuous monitoring of urinary output
Frequent monitoring of serum creatinine and blood urea nitrogen levels also provides valuable information regarding renal status.
What role do mediators play in septic shock?
They are powerful vasoconstrictors
They activate the sympathetic nervous system and cause intravascular clotting, contributing to acute renal failure.
What are the most important risk factors for gastrointestinal complications during shock?
Shock and administration of drugs used to treat shock
Splanchnic perfusion and intolerance to enteral nutrition may lead to hypoperfusion of the gut.
What can result from poor perfusion in the GI tract during shock?
Gastrointestinal bleeding and increased vascular permeability to intestinal bacteria
This can contribute to the development of sepsis and shock.
What is DIC characterized by?
Widespread activation of the coagulation system
This results in the formation of fibrin clots and thrombotic occlusion of small- and medium-sized vessels.
What is the estimated occurrence of clinically overt DIC in hospitalized patients?
1%
In people with sepsis, the occurrence can range from 30% to 50%.
What is MODS?
Multiple Organ Dysfunction Syndrome
It reflects the presence of altered organ function in a person who is acutely ill, often requiring intervention to maintain homeostasis.
What are major risk factors for the development of MODS?
- Severe trauma
- Sepsis
- Prolonged periods of hypotension
- Hepatic dysfunction
- Infarcted bowel
- Advanced age
- Alcohol abuse
These factors contribute to the severity of organ dysfunction.
What is the most frequent cause of death in the noncoronary intensive care unit?
MODS
Mortality rates can vary from 40% to 75% in people with MODS due to sepsis.
What is the pathogenesis of MODS primarily attributed to?
Elevated levels of endotoxins consistent with septic shock
Apoptosis is also delayed during sepsis, contributing to multiple organ failure.
What characterizes circulatory shock?
Body tissues are deprived of oxygen and cellular nutrients
This may develop due to various types of shock, including cardiogenic, hypovolemic, distributive, and obstructive.
What are the manifestations of hypovolemic shock?
- Thirst
- Changes in skin temperature
- Decreased blood pressure
- Increased heart rate
- Decreased venous pressure
- Decreased urine output
- Changes in sensorium
These manifestations are related to low peripheral blood flow and excessive sympathetic stimulation.
What can shock lead to regarding the lungs?
Acute Lung Injury/Acute Respiratory Distress Syndrome (ALI/ARDS)
This condition is characterized by changes in the permeability of the alveolar–capillary membrane.
What is a common complication of shock related to blood coagulation?
Disseminated Intravascular Coagulation (DIC)
DIC results from inappropriate activation of the coagulation cascade due to toxins or other products released during shock.
What is the main focus of the management of sepsis-induced DIC?
Treatment of the underlying disorder
Measures to interrupt the coagulation process, including platelet and factor replacement, are also recommended.
What is the mortality rate associated with failure of vital organs like the brain, liver, kidneys, and lungs?
High mortality rate
Mortality rates increase with the number of organs failing.
What is the likely treatment for severe upper GI bleeding?
IV proton pump inhibitors
This treatment is used to manage bleeding caused by shock.
