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Physiology And Pharmacology Of Systems > Integrated Cardiovascular Responses II, Hemorrhage, Shock and Ageing > Flashcards

Integrated Cardiovascular Responses II, Hemorrhage, Shock and Ageing Flashcards

1
Q

Definition of revealed haemorrhage

A

Obvious lending, quantity often hard to measure accurately

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2
Q

Definition of concealed haemorrhage

A

Bleeding not obvious but can occur in trauma

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3
Q

Definition of circulatory shock

A

Generalised inadequacy of blood flow throughout the body

Can lead to tissue damage due to inadequate O2 delivery and other nutrients

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4
Q

Definition of hypovolemia

A

State of decreased intravascular volume

May be due to loss of salt and water or decrease in blood volume

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5
Q

Definition of cardiogenic shock

A

Heart suddenly can’t pump enough blood to meet the needs of the body
Most often caused by MI

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6
Q

Definition of cardiopulmonary stretch receptors

A

Mechanoreceptors in the heart and large pulmonary vessels that respond to changes in the blood volume
Activate reflexes that reverse volume change, support BP and CO

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7
Q

Definition of haemodilution

A

Decreased conc of cells and solids in the blood resulting from gain of fluid

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8
Q

Definition of acute lung injury (ALI)

A

Characteristic form of parenchyma lung disease and represents a wide range of severity from short lived dyspnoea => terminal resp failure

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9
Q

Definition of acute respiratory distress syndrome (ARDS)

A

Life threatening condition when lungs cant provide enough O2

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10
Q

Definition of non progressive shock

A

Shock that gets better without treatment

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11
Q

Definition of refractory shock

A

Shock where death is inevitable

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12
Q

Definition of disseminated intravascular coagulation

A

Appearance of clots all over the body, cause damage

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13
Q

Definition of arteriosclerosis

A

Stiffening, increased fibrosis and calcification of arteries

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14
Q

What are the 2 main types of haemorrhage

A

Revealed, obvious bleeding, quantity hard to measure accurately
Concealed, can be due to trauma or other problems

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15
Q

What trauma can cause a concealed haemorrhage

A

Ruptured spleen
Pelvic floor fracture
Renal damage

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16
Q

What are the other possible causes of a concealed haemorrhage

A

Leaking aortic aneurysm
Ruptured ectopic pregnancy
Bleeding peptic ulcers before vomit

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17
Q

What are the possible effects of haemorrhage and what are they dependent on

A

Depends on the volume and speed of blood loss

  • Chronic, slow, persistent => Fe deficiency anaemia
  • Acute large loss => decrease in circulatory volume and circulatory shock
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18
Q

What is circulatory shock and what can it result it?

What can it be cause by

A

Generalised inadequate flow of the blood in the body
If prolonged, causes inadequate O2 and nutrient delivery => tissue damage

Caused by

  • Haemorrhage
  • Hypovolumia
  • Cardiogenic
  • Anaphalaxis
  • Sepsis
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19
Q

What are the signs and symptoms of circulatory shock

A

Anxiety, restless, confused, aggressive, lethargic, coma

Rapid shallow breaths, rapid weak pulse

Intense thirst, nausea

BP generally low, pulse pressure always low

Pale, grey cyanosis, clammy skin

Reduced urine output

Acidotic, decreased coagulation time, increased neutrophils

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20
Q

According to the WHO Haemorrhage classification system, what are the effects of minimal blood loss (<15%)

A

Shock unlikely in fit individual

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21
Q

According to the WHO haemorrhage classification system, what are the effects of mild blood loss (20-30%)

A

Generally induces shock

BP falls but not life threatening

22
Q

According to the WHO haemorrhage classification system, what are the effects of moderate blood loss (30-40%)

A

Severe shock, significant fall in BP and CO

May become refractory

23
Q

According to the WHO Haemorrhage classification system, what are the effects of severe blood loss (>50%)

A

Death inevitable

24
Q

How does the rate of blood loss affect your chances of survival according to the WHO

A

Rapid 30% loss => death

50% loss over 24hrs => could survive due to compensatory mechanisms

25
Q

What are the immediate forms on compensation

Why do we have compensation?

A

Maintain BP and CO despite the fall in BV

Reverse stress contraction
Reflex response
CNS ischaemic response
RAAS activation
Baroreceptor reflex
26
Q

What is reverse stress contraction

A

Most blood in veins => VC
Maintains venous P => maintains CVP => increased CO => increased BP
-Starts 10 mins after bleed

27
Q

What are the reflex responses

A

Increased HR and contractility => increased CO
Peripheral VC in skin, splanchnic, renal, muscle to increase BP
Increased sweating due to SNS activation via M3 cholinergic receptors

28
Q

What is the CNS ischaemic response

When is this activated

A

When MABP < 50mmHg

Profound peripheral VC => more blood to brain
Splanchnic, renal perfusion severely reduced => dangerous if sustained

29
Q

What happens when the RAAS system is activated

A

Electrolyte, water retention
VC, thirst, ADH

All maintain BV

30
Q

What is the baroreceptor reflex

A 
Decreased PNS stimulation
Increased SNS stimulation
-Increased HR, contractility, CO
-Venoconstriction => increased CVP
-VC of splanchnic, skin, renal, skeletal muscle => increase TPR
31
Q

Describe the acute response to severe blood loss

Describe the pathway of action

A

Cardiopulmonary stretch receptors in heart and large pulmonary vessels
Respond to changes in BV

Decreased BV => decreased stretch atria and cardiopulmonary receptor stimulation => hypothalamus and brain stem => increased ADH and A => increased VC => increased CVP, TPR, CO, BP => increased thirst and water reabsorption

32
Q

Describe blood volume and flow when there is no blood loss

A

All organs have an appropriate blood flow
Arterial P = normal
Vascular R = normal
F =normal

33
Q

Describe the flow of blood during a moderate haemorrhage

A

SNS VC of splanchnic, renal, muscle skin
-Vascular R increased => decreased F

Coronary, cerebral circulation
-Vascular R normal => normal F

MABP is normal
Decreased CO
Increased TPR but pulse P is low

34
Q

Describe what systolic and diastolic pressure is determined by and the effects of haemorrhage on pulse pressure

A

Systolic dominated by CO => falls
Diastolic determined by VC => rises

Pulse pressure is the difference between the 2 => weak

35
Q

How is blood volume restored

A

Internal transfusion associated with haemodilution (within hours)

Increased thirst, decreased urine production
Increased renal Na and water reabsorption (days)

36
Q

What is internal transfusion

A

VC and decreased venous P => decreased capillary hydrostatic P
Net absorption occurs as net force => -ve
Increased hepatic glucose production/release => increased capillary oncotic P => net absorption

37
Q

Describe the renal mechanisms that help restore the blood volume

A

Decreased BP, BV
Carotid sinus baroreceptors, decreased atrial stretch
Hypothalamus and brain stem

Increased thirst, ADH, SNS

Decreased diuretics, increased renin, Ang 2, aldosterone
Increased Na, water reabsorption

BV restored

38
Q

How does the quality of blood recover

A

Contents take around 6 weeks to recover (120 days = RBC lifespan)
Erythropoietin prod from kidney stimulated in renal hypoxia
Plasma proteins produced in liver
Reticulocytes count increases by 5-15% => increased RBC counts

39
Q

How to restore haemoglobin in the blood

A

[Hb] immediately after haemorrhage = normal as no of RBCs and plasma volume have fallen to the same extent
In haemodilution BV= normal but [Hb] and RBC nos fall

6 weeks until full recovery
Blood gas reduced O2 carrying capacity but effect lessened by decreased viscosity which favours perfusion

40
Q

What are the 3 other responses to haemorrhage

A

Increased ventilation

  • Decreased flow through carotid bodies
  • Acidosis, decreased pH

Increased platelet and fibrinogen

  • Decreased coagulation time
  • All clotting factors decreased, all used up

Increased WBC for ALI/ARDS

41
Q

What is non progressive shock and how long does it take to restore the blood volume

A

Gets better without treatment (<20% blood loss)
Restored within 16-24 hours

After a blood donation

42
Q

What is refractory shock and what should you do before you reach this stage

A

If loss, greater than 30%, CO may improve due to compensation but will worsen unless transfusion given within reversible shock phase (golden hour)

Transfusions in irreversible shock cant help as irreversible cardiac damage has occurred

43
Q

What happens during circulatory failure

A

Decreased BP
Decreased perfusion
Hypoxia, increased acidosis, toxins and DIC
Decreased cardiac function and CO
Decreased vascular tone, increased vascular permeability and fluid loss to tissues
Loss of proteins to TF, loss of oncotic P grad

Lead to multi organ failure
Renal failure
Intestinal mucosal damage
Sepsis
Cardiac failure
ARDS
Hepatic failure
44
Q

What are the 4 cardiovascular effects of ageing

A

Changes in artery wall structure (arteriosclerosis)
Increase in systolic, decrease in diastolic
Decreased baroreceptor sensitivity
Impaired cardiac performance in exercise

45
Q

How does systolic and diastolic pressure change in ageing

A

Systolic P increases => HTN

Diastolic P increases then falls

46
Q

Describe the vascular changes in ageing

A

Decreased compliance in larger arteries

Elastic layers => thin and fragmented => arterial dilation
Collagen increases => increased stiffness, intimal layer thickens

SNS increases, NO release decreases => Increase in TPR, decrease in VD => decreased muscle flow in exercise

Lead to increase in systolic, pulse pressure and afterload

47
Q

Describe how arterial stiffening can lead to isolated systolic hypertension and widening of pulse pressure

A

Normally pulse wave reflected back by branching arteries
With age and HTN, pulse wave reflected back faster due to decreased compliance

Pulse wave returns faster, merges with forward wave => increased systolic
Decreased elasticity => decreased F => decreased diastolic

Results in widening of pulse pressure

48
Q

Describe the cardiac changes in ageing at rest

A

Little effect on resting cardiac function

Cardiac fibrosis => decreased relaxation and diastolic filling => decreased CO

49
Q

Describe the cardiac changes in ageing in stress

A

Less able to increase CO in stress

  • Max HR = 220 - age
  • Decreased contractility => decreased SV

Decreased B1 response, decrease in myocytes

Increased afterload due to increased stiffness => decreased SV and CO => increased cardiac O2 demand

50
Q

Describe how the cardiovascular reflexes change with age

A

Baroreceptor reflex still works but slower
-SNS, PSN responses impaired

Cardiopulmonary reflexes attenuated
-Fluid and electrolyte imbalances, harder to deal with

Physiology And Pharmacology Of Systems (22 decks)

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