Chapter 4: Shock

Question 1

What is shock?

Answer 1

Shock is a state in which diminished cardiac output or reduced effective circulating blood volume impairs tissue perfusion and leads to cellular hypoxia

Question 2

Is shock injury reversible?

Answer 2

Yes, unless prolonged

Question 3

Shock may complicate severe hemorrhage, extensive trauma or burns, myocardial infarction, pulmonary embolism, and microbial sepsis. Its causes fall into three general categories. What are these three categories?

Answer 3

• Cardiogenic shock
• Hypovolemic shock
• Septic shock is triggered by microbial infections and is associated with severe systemic inflammatory response syndrome (SIRS)

Question 4

Where does cariogenic shock result from?

Answer 4

Cardiogenic shock results from low cardiac output as a result of myocardial pump failure. It may be caused by myocardial damage (infarction), ventricular arrhythmias, extrinsic compression (cardiac tamponade), or outflow obstruction (e.g., pulmonary embolism)

Question 5

Where does hypovolemic shock result from?

Answer 5

Hypovolemic shock results from low cardiac output due to loss of blood or plasma volume (e.g., resulting from hemorrhage or fluid loss from severe burns)

Question 6

Where can SIRS (besides microbes) be triggered by?

Answer 6

SIRS may be triggered by a variety of insults, including burns, trauma, and/or pancreatitis

Question 7

What is the common pathogenic mechanism for septic shock?

Answer 7

The common pathogenic mechanism is a massive outpouring of inflammatory mediators from innate and adaptive immune cells that produce arterial vasodilation, vascular leakage, and venous blood pooling. These cardiovascular abnormalities result in tissue hypoperfusion, cellular hypoxia, and metabolic derangements that lead to organ dysfunction and, if severe and persistent, organ failure and death.

Question 8

What factors play major roles int he pathophysiology of septic shock?

Answer 8

• Inflammatory and counter-inflammatory responses
• Endothelial activation and injury
• Induction of a procoagulant state
• Metabolic abnormalities
• Organ dysfunction

Question 9

How is septic shock treated?

Answer 9

Antibiotics

Question 10

Please see figure 4.19

Answer 10

I did not include the text of ‘pathology of septic shock’ in these flashcards. To my belief, it is way too much and too detailed, so personally I am choosing to skip this, to focus on other subjects. However feel free to read/study it! (p116-118)

Question 11

Will shock eventually lead to death?

Answer 11

Yes, if the underlying problems are not corrected

Question 12

(hypovolemic) Shock tends to evolve through three general stages. What are these? (+describe)

Answer 12

• An initial nonprogressive stage during which reflex compensatory mechanisms are activated and vital organ perfusion is maintained,
• A progressive stage characterized by tissue hypo-perfusion and onset of worsening circulatory and metabolic derangement, including acidosis,
• An irreversible stage in which cellular and tissue injury is so severe that even if the hemodynamic defects are corrected, survival is not possible.

Question 13

In the early nonprogressive phase of shock, various neurohumoral mechanisms help maintain cardiac output and blood pressure. Where some examples of these mechanisms?

(please don’t learn by heart)

Answer 13

These mechanisms include baroreceptor reflexes, release of catecholamines and anti-diuretic hormone, activation of the renin-angiotensin-aldersterone axis, and generalized sympathetic stimulation

Question 14

What happens because of the mechanisms that maintain the cardiac output and blood pressure?

Answer 14

The net effect is tachycardia, peripheral vasoconstriction, and renal fluid conservation; cutaneous vasoconstriction causes the characteristic “shocky” skin coolness and pallor

Question 15

If the underlying causes are not corrected, shock passes imperceptibly to the progressive phase, which as noted is characterized by widespread tissue hypoxia. What are some examples that happen on cellular/molecular level?

(don’t learn by heart svp)

Answer 15

intracellular aerobic respiration is replaced by anaerobic glycolysis with excessive production of lactic acid. The resultant metabolic lactic acidosis lowers the tissue pH, which blunts the vasomotor response; arterioles dilate, and blood begins to pool in the microcirculation

Question 16

In the absence of appropriate intervention, or in severe cases, the process eventually enters an irreversible stage. Name some examples of what happens on molecular/cellular leve

Answer 16

• Lysosomal enzyme leakage, aggravating shock state.
• NO synthesis -> myocardial function worsens
• Ischemic bowel allowing intestinal flora to enter circulation
• renal failure

Question 17

What are symptoms of shock?

Answer 17

In hypovolemic and cardiogenic shock, patients exhibit hypotension, a weak rapid pulse, tachypnea, and cool, clammy, cyanotic skin. In septic shock, the skin may be warm and flushed owing to peripheral vasodilation.