19A13: Exam Report
Classify circulatory shock and provide examples (40% marks). Outline the cardiovascular responses (60%)
83% of candidates passed this question.
Answers should have included the various types of shock and provided clear examples.
Cardiovascular responses including sensor, integrator, effector mechanisms were necessary to pass.
G6 SYL2017 / 19A13: Classify circulatory shock and provide examples (40% marks). Outline the cardiovascular responses (60%)
Definition
A state of circulatory failure characterised by globally impaired tissue perfusion that is insufficient to meet body demands
Classification
- CARDIOGENIC
- OBSTRUCTIVE
- HYPOVOLAEMIC
- DISTRIBUTIVE
- ENDOCRINE
- ERROR
Cardiogenic
- Impaired contractility
- Dysrrhythmia
- Valvular dysfunction
- LVOT obstruction
Obstructive
- In circulatory system → massive PE
- External to circulatory system → Tension PTX
Hypovolaemic Shock
- Haemorrhage
- Fluid loss
Distributive
- i.e. sepsis, neurogenic, liver failure, anaphylaxis
Endocrine
- Adrenal insufficiency
- Hypo/Hyperthyroidism
Errors
- Arterial line transducer higher than RA
Cardiovascular Response
Sensor
Baroreceptors
MAP < 60
↓firing rate of BaroR afferents
Via CN X & IX
Chemoreceptors
↓tissue perfusion
Hypoxia
Anaerobic Metabolism
Stimulates Central & Peripheral ChemoR
Via CN X & IX
Ischaemic Cns Response
MAP < 60
Integrator
Baroreceptors
Vasomotor & cardiac centres of Lower Pons & Medulla
Chemoreceptors
Respiratory centre in RAS of lower pons & Medulla
Ischaemic Cns Response
Vasomotor & cardiac centres of Lower Pons & Medulla
Effector
Baroreceptors
ANS by negative feedback
↓BP → ↑symp. & ↓parasympathetic ouput
Chemoreceptors
↑symp outflow
↑MV
Ischaemic Cns Response
Mass SYMPATHETIC OUTFLOW
Sympathetic Stimulation:
- Adr & NA released from adrenal medulla and sympathetic n terminals ↑x50
@ Heart
- b1 receptor activation
- ↑HR & FoC
- ↑CO
@ Arteriolar
- a1 activation
- ↑SVR
- Maintenance of BP
- Mass VC of cutaneous, sk m, splanchinic vessels to redirect blood
- Renal A VC → especially supply to outer layers of renal cortex
- Cardiac/Cerebral vessel sparing
@Venous
- Mobilisation of reservoirs; lungs, liver, cutaneous
- ↑VR = ↑CO