Integrated Cardiovascular Responses II, Hemorrhage, Shock and Ageing

Question 1

Definition of revealed haemorrhage

Answer 1

Obvious lending, quantity often hard to measure accurately

Question 2

Definition of concealed haemorrhage

Answer 2

Bleeding not obvious but can occur in trauma

Question 3

Definition of circulatory shock

Answer 3

Generalised inadequacy of blood flow throughout the body

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

Question 4

Definition of hypovolemia

Answer 4

State of decreased intravascular volume

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

Question 5

Definition of cardiogenic shock

Answer 5

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

Question 6

Definition of cardiopulmonary stretch receptors

Answer 6

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

Question 7

Definition of haemodilution

Answer 7

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

Question 8

Definition of acute lung injury (ALI)

Answer 8

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

Question 9

Definition of acute respiratory distress syndrome (ARDS)

Answer 9

Life threatening condition when lungs cant provide enough O2

Question 10

Definition of non progressive shock

Answer 10

Shock that gets better without treatment

Question 11

Definition of refractory shock

Answer 11

Shock where death is inevitable

Question 12

Definition of disseminated intravascular coagulation

Answer 12

Appearance of clots all over the body, cause damage

Question 13

Definition of arteriosclerosis

Answer 13

Stiffening, increased fibrosis and calcification of arteries

Question 14

What are the 2 main types of haemorrhage

Answer 14

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

Question 15

What trauma can cause a concealed haemorrhage

Answer 15

Ruptured spleen
Pelvic floor fracture
Renal damage

Question 16

What are the other possible causes of a concealed haemorrhage

Answer 16

Leaking aortic aneurysm
Ruptured ectopic pregnancy
Bleeding peptic ulcers before vomit

Question 17

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

Answer 17

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

Question 18

What is circulatory shock and what can it result it?

What can it be cause by

Answer 18

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

Question 19

What are the signs and symptoms of circulatory shock

Answer 19

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

Question 20

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

Answer 20

Shock unlikely in fit individual

Question 21

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

Answer 21

Generally induces shock

BP falls but not life threatening

Question 22

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

Answer 22

Severe shock, significant fall in BP and CO

May become refractory

Question 23

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

Answer 23

Death inevitable

Question 24

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

Answer 24

Rapid 30% loss => death

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

Question 25

What are the immediate forms on compensation | Why do we have compensation?

Answer 25

Maintain BP and CO despite the fall in BV ``` Reverse stress contraction Reflex response CNS ischaemic response RAAS activation Baroreceptor reflex ```

Question 26

What is reverse stress contraction

Answer 26

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

Question 27

What are the reflex responses

Answer 27

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

Question 28

What is the CNS ischaemic response | When is this activated

Answer 28

When MABP < 50mmHg Profound peripheral VC => more blood to brain Splanchnic, renal perfusion severely reduced => dangerous if sustained

Question 29

What happens when the RAAS system is activated

Answer 29

Electrolyte, water retention VC, thirst, ADH All maintain BV

Question 30

What is the baroreceptor reflex

Answer 30

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

Question 31

Describe the acute response to severe blood loss Describe the pathway of action

Answer 31

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

Question 32

Describe blood volume and flow when there is no blood loss

Answer 32

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

Question 33

Describe the flow of blood during a moderate haemorrhage

Answer 33

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

Question 34

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

Answer 34

Systolic dominated by CO => falls Diastolic determined by VC => rises Pulse pressure is the difference between the 2 => weak

Question 35

How is blood volume restored

Answer 35

Internal transfusion associated with haemodilution (within hours) Increased thirst, decreased urine production Increased renal Na and water reabsorption (days)

Question 36

What is internal transfusion

Answer 36

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

Question 37

Describe the renal mechanisms that help restore the blood volume

Answer 37

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

Question 38

How does the quality of blood recover

Answer 38

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

Question 39

How to restore haemoglobin in the blood

Answer 39

[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

Question 40

What are the 3 other responses to haemorrhage

Answer 40

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

Question 41

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

Answer 41

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

Question 42

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

Answer 42

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

Question 43

What happens during circulatory failure

Answer 43

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 ```

Question 44

What are the 4 cardiovascular effects of ageing

Answer 44

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

Question 45

How does systolic and diastolic pressure change in ageing

Answer 45

Systolic P increases => HTN | Diastolic P increases then falls

Question 46

Describe the vascular changes in ageing

Answer 46

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

Question 47

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

Answer 47

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

Question 48

Describe the cardiac changes in ageing at rest

Answer 48

Little effect on resting cardiac function | Cardiac fibrosis => decreased relaxation and diastolic filling => decreased CO

Question 49

Describe the cardiac changes in ageing in stress

Answer 49

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

Question 50

Describe how the cardiovascular reflexes change with age

Answer 50

Baroreceptor reflex still works but slower -SNS, PSN responses impaired Cardiopulmonary reflexes attenuated -Fluid and electrolyte imbalances, harder to deal with