Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Cardiovascular system > Lecture 20- Haemodynamic shock > Flashcards

Lecture 20- Haemodynamic shock Flashcards

1
Q

To control arterial BP

A

Cardiac output and peripheral resistance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Mean arterial BP=

A

CO xTPR

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

CO=

A

SV x HR

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Therefore: Mean arterial BP=

A

SV x HR x TPR

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Calculating maBP=

A

diastolic pressure + 1/3 pulse pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

which organs will constrict blood vessels to maintain blood pressure (altered peripheral resistance)

A

heart

brain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Haemodynamic shock

A

Acute condition of inadequate blood flow throughout the body

  • Catastrophic fall in aBP leads to circulatory shock
  • Inadequate flow= vital organs not perfused
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

when thinking of the causes of shock think

A

BP= CO xTPR

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

fall in CO

A
  • Mechanical- pump cannot fill properly e.g. hypertrophy
  • Pump failure- arrhythmia
  • Loss of blood volume- stabbing
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

fall in TPR

A

Excessive vasodilation e.g. sepsis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Shock due to fall in CO

Always a dramatic drop in arterial blood pressure.

A

1.Cardiogenic shock (pump failure)

2.Mechanical shock (obstructive)

3.Hypovolaemic shock

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

1.Cardiogenic shock (pump failure)

A

Ventricle cannot empty properly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

1.Mechanical shock (obstructive)

A

Ventricle cannot fill properly

Cardiac tamponade

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

3.Hypovolaemic shock

A

Reduced blood volume leads to poor venous return

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

cardiogenic shock occurs when

A
  • Acute failure of the heart to maintain CO- pump failure
  • Heart is filling but not pumping properly
  • Central venous pressure may increase
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

causes of cardiogenic shock

A
  • Following MI- damage to left ventricle
  • Due to serious arrhythmias
    • Heart block
    • Low heart rate
    • Profound bradycardia
    • Profound tachycardia
      • Not enough time for the ventricles to fill in diastole
    • Ventricular tachycardia
    • Acute worsening of heart failure
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

effect of cardiogenic shock

A
  • Poor perfusion of tissue
  • Poorly perfused coronary artery
    • Exacerbate the problem
  • Kidney poorly perfused
    • Will produce smaller amounts of dark urine
  • May increase or decrease heart rate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

mechanical shock due to

A

Restricted filling i.e. heart cant contract properly e.g. after a stab to the heart the blood that fills will increase pericardial fluid compressing it. No problem with emptying (continued electrical activity)

e.g. cardiac tamponade

19
Q

cardiac tamponade

A
  • Blood or fluid build up in pericardial space
  • Restricts filling of the heart- limits end diastolic volume
  • Affects left and right side of the heart
20
Q

causes of mechanical shock

A
  • High central venous pressure
  • Low arterial blood pressure (shock)
  • Reduction in stroke volume- reduces CO- reduce maBP
  • Rapid heart beat
21
Q
A
22
Q

mechanical shock and pulmonary embolism

A
  • Massive PE (most will be smaller and will not cause shock)
  • Embolus occludes a large pulmonary artery
    • Pulmonary artery pressure is high
    • Right ventricle cannot empty
    • Central venous pressure high
    • Reduced return of blood to left heart
    • Limits filling of the left heart
      • Left atrial pressure is low
      • Arterial pressure low- SHOCK
  • Also chest pain and dyspnoea
23
Q

How might an embolus reach the lung?

A
  • Typically due to deep vein thrombosis
  • Portion of thrombus breaks off (emboli)
  • Travels in venous system to right side of the heart
  • Pumped out via pulmonary artery to lungs
24
Q

hypovolaemic shock occurs due to

A

reduced blood volume 9most commonly due to haemorrhage)

25
Q

<20% blood loss

A

unlikely to cause shock

26
Q

>20-30% blood loss

A
  • signs of shock
27
Q

30-40% blood loss

A

Substantial decrease in mean aBP and serious shock response

28
Q

Severity of shock is related

A

to amount and speed of blood loss

29
Q

during haemorrhage

A
  • Venous pressure falls
  • CO falls (starlings law)
  • AP falls
  • Detected b baroreceptors
    • Compensatory response
      • Increase heart rate (chronotropy)and contractility (inotropy)
      • Contractility- increase in slope
30
Q
A
31
Q

Normally at the capillaries you get a small net movement of fluid out to the tissues…this then returns to the venous system via

A

the lymphatic drainage

32
Q
A
33
Q

In hypovolaemic shock this reverses

Internal transfusion

Increased peripheral resistances reduces the capillary hydrostatic pressure

Net movement of fluid into capillaries

Due to:

A
  • Arterials constrict peripherally to maintains arterial blood pressure
  • Downstream pressure is lower- in the capillariesà less fluid forced out due to hydrostatic pressure
34
Q

signs of hypovolaemic shock in a patient

A
  • Tachycardia
  • Weak pulse
  • Pale skin
  • Cold, clammy extremities (sympathetic adrenergic sweating)
  • Low central venous pressure
    • Less blood in the system
35
Q

Hypovolaemic shock can also due to:

A
  • Severe burns
  • Severe diarrhoea or vomiting and loss of Na+
36
Q

Danger of decompensation

A

Peripheral vasoconstriction (shutdown) impairs tissue perfusion (to increase BP)

  • Tissue damage due to hypoxia
  • Release of chemical mediators- vasodilators
    • TPR falls
    • BP falls dramatically
    • Vital organs no longer perfuses
    • Multi system failure
37
Q

long term responses to hypovolaemic shock

A

RAAS

ADH

38
Q

If you get a 20% of blood volume loss–> restoration of body fluid volume in

A

3 days (if salt and water intake are adequate)

39
Q

cardiac arrest is

A
  • Unresponsiveness associated with lack of pulse
  • Heart has stopped or has ceased to pump affectively
40
Q

causes of cardiac arrest

A
  1. Asystole (loss of electrical and mechanical activity)
  2. Can get pulseless electrical activity (PEA)
  3. Ventricular fibrillation (uncoordinated electrical activity)
  • Most common for of cardiac arrest
  • Often following MI
  • Or electrolyte imbalance
  • Or some arrythmias (e.g. long QT and Torsades de Pointes)
41
Q

treatment of cardiac arrest

A
  • Basic life support- chest compression and external ventilation
  • Advanced life support
    • Defibrillation
      • Electric current delivered to the heart
      • Depolarises all the cells at once- puts them into the refractory period
      • Allows coordinated electrical activity of the heart
    • Adrenaline
      • Enhances myocardial function
      • Increases peripheral resistance
42
Q

distributive shocck

A
  • Low resistance shock (normovolaemic- normal volume)
  • Profound peripheral vasodilation- decrease TPR
  • Blood vol= constant
    *
43
Q

what causes distributive shock

A

Toxic shock

Anaphylactic shock

44
Q

toxic shock

A
  • In response to sepsis- serious life-threatening response to infection
  • Can lead to septic shock
    • Endotoxins released by circulating bacteria
    • Chemokines released in response to inflammatory response- profound vasodilation
      • Dramatic fall in peripheral resistance, decrease in maBP
      • Hypoperfusion of vital organs
      • Also really leaky capillaries- reduced blood volume
      • Increased coagulation and localised hypo-perfusion (fingers and toes)

Cardiovascular system (30 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions