L63 – Shock and Heart Failure Flashcards
(51 cards)
Define Shock?
Systemic, Generalized hypoperfusion of all cells and tissues due to failure of circulatory system
resulting in inadequate effective circulating volume
What are the 3 causes of shock?
Reduction in blood volume
Reduction in cardiac output
Redistribution of blood
What are the initial and protracted recovery of shock?
At first: reversible
Protracted: irreversible injury, death
What are the 4 types of Shock?
Cardiogenic
Anaphylactic
Septic
Hypovoleamic
What is the cause of Hypovolaemic shock?
insufficient blood volume due to:
Hemorrhage > external and internal
Fluid loss > dehydration
Name some causes of external and internal hemorrhage?
External: chop / gunshot wounds, laceration
Internal:
Gastro-intestinal bleeding
Hemoperitoneum due to ruptured aortic aneurysm
Ruptured ectopic pregnancy
What is the normal plasma, interstitial and intracellular fluid volumes?
Plasma 3 L
Interstitial fluid 11 L
Intracellular fluid 28 L
What is the normal blood volume?
5L > 60% plasma and 40% RBC
Body can compensate up to how many percentage fluid loss?
up to 20%
What is the effect of <10% volume loss on cardiac output ?
symptomatic (no change in arterial pressure, cardiac output)
What is the effect of 15%-25% volume loss on cardiac output ?
cardiac output starts to drop»_space; compensated hypotension
Explain the mechanism for maintaining BP in hypovolemia?
Sympathetico-adrenal
stimulation> release catecholamines > peripheral vasoconstriction
Atrial stretch receptor firing decrease > CVS centre > hypothalamus > release ADH to increase blood volume
Autoregulation > maintain perfusion to brain, heart but not other organs
Renal RAAS activation
What are the 4 stages of hypovolemic shock?
Asymptotic (<10%)
Early stage (15-25%)
Progressive/ advanced stage
Irreversible shock
How does progressive/ advanced stage hypovolemia occur?
when no therapeutic intervention is given for the early stage
What are the results of progressive/ advanced stage hypovolemia?
Same mechanisms stimulated in early stage to restore volume
Unique features:
- Irreversible damage to organs and tissue due to impaired perfusion, hypoxia
- Multi-organ breakdown by ischaemia
- Cardiac depression
- Tissue inflammation further decrease volume and CO
Explain the vicious cycle in progressive or decompensated shock?
Decreased CO > cardiac depression > decrease tissue perfusion > tissue necrosis
> Release of toxins > increase capillary permeability > further loss in volume
> further decrease in CO
What causes cardiac depression?
Decreased cardiac nutrition
How does decrease blood flow to brain lead to vascular dilation?
Decreased flow to brain > decreased nutrition of brain
> Decrease VASOMOTOR activity
Vascular dilation
What type of hypersensitivity reaction is Anaphylactic shock?
Type I
What triggers anaphylactic shock?
Specific antigens
+ prior sensitization
How does anaphylactic shock lead to DAD?
injured endothelium, epithelium»_space;
Inflammatory mediators cause Vasodilatation of
micro-circulation
> > Interstitial edema, congested capillary, hyperplasia of type II pneumocyte and hyaline membrane formation
> > Exudate leak into alveolar airspace»_space; DAD
WHat is the treatment for anaphylactic shock?
inject adrenaline»_space; peripheral vasoconstriction to conserve blood volume
What are some symptoms of anaphylactic shock?
Swollen lips, eyes, soft tissue > skin rashes
Swollen mucosal lining > breathing difficulty
What occurs in cardiogenic shock?
Suddenly Weakened heart cannot pump enough blood to meet body’s needs
