L63 – Shock and Heart Failure Flashcards Preview

MBBS I CPRS > L63 – Shock and Heart Failure > Flashcards

Flashcards in L63 – Shock and Heart Failure Deck (51):
1

Define Shock?

Systemic, Generalized hypoperfusion of all cells and tissues due to failure of circulatory system

resulting in inadequate effective circulating volume

2

What are the 3 causes of shock?

Reduction in blood volume
Reduction in cardiac output
Redistribution of blood

3

What are the initial and protracted recovery of shock?

At first: reversible

Protracted: irreversible injury, death

4

What are the 4 types of Shock?

Cardiogenic
Anaphylactic
Septic
Hypovoleamic

5

What is the cause of Hypovolaemic shock?

insufficient blood volume due to:

Hemorrhage > external and internal
Fluid loss > dehydration

6

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

7

What is the normal plasma, interstitial and intracellular fluid volumes?

Plasma 3 L
Interstitial fluid 11 L
Intracellular fluid 28 L

8

What is the normal blood volume?

5L > 60% plasma and 40% RBC

9

Body can compensate up to how many percentage fluid loss?

up to 20%

10

What is the effect of <10% volume loss on cardiac output ?

symptomatic (no change in arterial pressure, cardiac output)

11

What is the effect of 15%-25% volume loss on cardiac output ?

cardiac output starts to drop >> compensated hypotension

12

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

13

What are the 4 stages of hypovolemic shock?

Asymptotic (<10%)

Early stage (15-25%)

Progressive/ advanced stage

Irreversible shock

14

How does progressive/ advanced stage hypovolemia occur?

when no therapeutic intervention is given for the early stage

15

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

16

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

17

What causes cardiac depression?

Decreased cardiac nutrition

18

How does decrease blood flow to brain lead to vascular dilation?

Decreased flow to brain > decreased nutrition of brain

> Decrease VASOMOTOR activity
> Vascular dilation

19

What type of hypersensitivity reaction is Anaphylactic shock?

Type I

20

What triggers anaphylactic shock?

Specific antigens
+ prior sensitization

21

How does anaphylactic shock lead to DAD?

injured endothelium, epithelium >>
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 >> DAD

22

WHat is the treatment for anaphylactic shock?

inject adrenaline >> peripheral vasoconstriction to conserve blood volume

23

What are some symptoms of anaphylactic shock?

 Swollen lips, eyes, soft tissue > skin rashes
 Swollen mucosal lining > breathing difficulty

24

What occurs in cardiogenic shock?

Suddenly Weakened heart cannot pump enough blood to meet body's needs

25

What are the causes of cardiogenic shock?

 Acute myocardial infarction
 Cardiac tamponade

26

What are the causes of cardiac tamponade?

Fluid buildup in pericardial sac > exert pressure on heart

due to:
Ruptured MI
Ruptured dissecting aortic aneurysm
Penetrating injury to heart

27

What is the leading cause of septic shock?

Severe infection by Gram-negative, endotoxin-producing bacteria

28

What are some predisposing factors of septic shock?

- Debilitating diseases (e.g. neoplasm)
- Mechanical carriage of bacteria into blood during surgery
- Burns
- Age
- Health status (e.g. nutrition)

29

Compare cardiogenic and septic shock. Which one causes more death in hospital settings?

Cardiogenic

30

What is the pathogenesis of septic shock?

1. Endotoxins > extensive endothelial damage

2. Disseminated intravascular coagulopathy

3. Inflammatory reaction

31

What are the common causes of septic shock?

 Peritonitis

 Infection spreading into blood from kidney, urinary tract (E. coli)

 Generalised infection from streptococcal / staphylococcus skin infections

 Generalized gangernous infections

32

Name 2 causes of Peritonitis that can lead to septic shock?

From instrumental abortion and ruptured guts

33

What is the difference between procoagulant and anti-fibrinolytic factors?

Procoagulant:
 Activate clotting factors

anti-fibrinolytic:
 Consume clotting factors

34

What is the result of Histamines, complements activating endothelium?

Vasodilation
Increase vascular permeability
Inflammatory reaction

35

Heart failure can be due to pressure or volume problems?

Both

36

What is ejection fraction?

fraction of volume of blood in left ventricle that is pumped out with each ejection / contraction

37

How is ejection fraction calculated?

(EDV - ESV)/ EDV

EDV = end-diastolic volume
ESV = end-systolic volume

38

What is the normal and abnormal ejection fraction?

Normal = 55-70%;
Abnormal = <40%

39

What are the vasoconstricting systems?

RAAS
Vasopressin
Sympathetic tone

40

What are the vasodilating systems?

Vasodilator prostaglandins
Endothelium relaxing factors
Atrial natriuretic factor

41

What are the most common causes of Heart failure with decreased ejection fraction?

 Ischaemic heart disease; or
 Diseases that result in damage to heart muscles

42

What are some muscle abnormalities of the heart? (diseases)

MI
Cardiomyopathy
Myocarditis

43

What diseases affect the coordination of heart pumping?

Valvular problems
Abnormal rhythms (nerve issue)

44

3 ways the heart fails?

Muscel abnormality

Uncoordianted pumping

Physically prevented from pumping

45

How does heart failure with decreased ejection fraction lead to pulmonary regurgitation?

Ventricular wall is weakened, dilated:
End-diastolic volume increases and ejection fraction decreases

Increase residual volume leads to regurgitation to pulmonary vessels

46

What is the common cause of Heart failure without drop in ejection fraction?

**Chronic hypertension

LV hypertrophy and decrease filling

47

How come ejection fraction is still normal in some heart failures?

Decrease in stroke volume

but relative to volume of LV, the ejection fraction maintains normal

48

What are the clinical examination results of heart failure?

Elevated JVP
Hepatojugular reflux
Third heart sound

49

What is the function of nitroglycerin?

Vasodilator and pain relieve

50

What is the function of Digitalis?

Anti-arrhythmic

51

What is cardiac ablation?

scar or destroy tissue for fibrillation

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