Hypertensive- Shock 2 Flashcards Preview

Term 5 - PathoPhysio > Hypertensive- Shock 2 > Flashcards

Flashcards in Hypertensive- Shock 2 Deck (15):
1

The causes and types of shock:

  1. Hypovolemic shock:
    • Inadequate volume of blood to fill the vascular system
  2. Distributive shock (also called vasogenic or low-resistance shock):
    • Increased size of the vascular system produced by vasodilation in the presence of a normal blood volume
  3. Cardiogenic shock:
    • Inadequate output of the heart as a result of myocardial abnormalities
  4. Obstructive shock:
    • Inadequate cardiac output as a result of obstruction of blood flow in the lungs or heart

2

Physical findings in Hypovolemic Shock:

  • Hypotension (systolic pressure <90)
  • A rapid, low volume, thready pulse
  • Cold, pale, clammy skin
  • Intense thirst
  • Rapid respiration
  • Restlessness or Low activity
  • Markedly decreased urine output
  • Altered mental status
  • Do not rely on systolic BP as the main indicator of shock. Compensatory mechanisms prevent a significant decrease in systolic BP until the patient has lost 30% of the blood volume

3

Compensatory reactions activated by Hypovolemic Shock:

  • Vasoconstriction & consequences
  • Tachycardia
  • Venoconstriction
  • Tachypnea – cause and benefit
  • Increased movement of interstitial fluid into capillaries
  • Increased secretion of ADH
  • Increased secretion of glucocorticoids
  • Stimulation of renin-angiotensin-aldosterone
  • Increased secretion of erythropoietin
  • Increased synthesis of plasma proteins

4

Hypovolemic shock:

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5

Hypovolemic shock:

Baroreceptor response to decrease in BP

 

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6

  • Hypovolemic shock:
  • Compensatory Mechanisms
  • Neurohormonal Activation

  • Angiotensin II
  • Epinephrine
  • Norepinephrine
  • Vasopressin (ADH)
  • ACTH
  • Aldosterone

7

Hypovolemic shock:

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8

Consequences of increased vasomotor discharge during hypovolemic shock:

  1. Vasoconstriction is generalized, sparing only the vessels of the brain and the heart
  2. Vasoconstriction in the skin - Coolness and pallor
  3. Vasoconstriction in the kidney – Drop in GFR. This reduces water loss, but it reaches a point at which nitrogenous products of metabolism accumulate in the blood (prerenal azotemia). If hypotension is prolonged, there may be severe renal tubular damage, leading to acute renal failure.

9

Reason for tachypnea and its importance in hypovolemia:

  • The fall in blood pressure and the loss of red cells results in stimulation of the carotid and aortic chemoreceptors → stimulation of respiratory center→ Chemoreceptor reflex
  • Stimulation of respiration increases thoracic pumping and improves venous return
  • Stimulation of respiration also increases vasoconstrictor discharge

10

Hypovolemic shock:

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11

Hypovolemic shock:

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12

Hypovolemic shock:

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13

Hypovolemic shock:

Refractory Shock:

  • The shock persists for hours and eventually reaches a state in which there is no longer any response to vasopressor drugs
  • Even if the blood volume is returned to normal, cardiac output remains depressed
  • Factors that make shock refractory are:
    • Precapillary sphincters are constricted for several hours but then relax while postcapillary venules remain constricted. Therefore, blood flows into the capillaries and remains there.
    • Cerebral ischemia depresses vasomotor and cardiac discharge, causing blood pressure to fall and making the shock worse.
    • Reduced myocardial blood flow.

14

Traumatic Hypovolemic Shock:

  • Traumatic shock involves severe damage to muscle and bone - as seen in battle casualties and automobile accident victims
  • Significant bleeding into the injured areas
  • Breakdown of skeletal muscle is a serious additional problem when shock is accompanied by extensive crushing of muscle (crush syndrome)
  • Free radicals generated at the sites cause further tissue destruction (reperfusion-induced injury)
  • Increased Ca 2+ in damaged cells can reach toxic levels
  • Large amounts of K+ enter the circulation
  • Myoglobinuria worsens renal failure

15

Hypovolemic shock:

A complication of shock that has a very high mortality rate is:

  • Pulmonary damage with production of acute respiratory distress syndrome (ARDS)
  • The cause for ARDS: Capillary endothelial cell damage and damage to alveolar epithelial cells with the release of cytokines