Cardio physiology Flashcards
How does acidosis cause low BP?
Acidosis causes relaxation of precapillary sphincter causing increased flow in capillary bed and decreased systemic BP
Frank-Starling law
Increased energy causing increased contractility
Cardiac output
CO = SV x HR
Stroke volume
SV = EDV - ESV
Ejection fraction
EJ = SV / EDV
Normal pulse pressure
40mmHg
MAP
MAP = diastolic + 1/3 pulse pressure
Absent a waves
AF
Large a waves
Pulmonary hypertension
Pulmonary stenosis
Cannon a waves
Complete heart block
Large v waves
Tricuspid regurgitation
Rise in JVP on inspiration (Kussmaul’s sign)
Constrictive pericarditis
Carotid body
Chemoreceptors
Found at bifurcation of carotids
Carotid sinus
Baroreceptors
Found in adventitia of internal carotid
% estimated blood loss
I - <15%
II - 15-30
III - 30-40
IV - >40
Neurogenic shock
High injury
Interrupts sympathetic response - bradycardia, hypotension, hypothermia
Spinal shock
Injury to cord - bruising, swelling, ischaemia
Immediate loss below injury - areflexia, flaccid paralysis
Nerves involved in bulb-cavernosis reflex
S2 and S3
Spinal injury level causing autonomic dysreflexia
T6 or above
Pathophysiology of autonomic dysreflexia
Vasodilation above injury - flushed, bradycardia, headache
Vasoconstriction below injury - pale, cool, clammy, HTN
Most common cervical fracture from seat belt injury
C2 odontoid peg
Aortic deceleration
Beyond L subclavian
Most common lumbar fracture from seat belt injury
L2
Sick sinus syndrome
Bradycardia
Depolarisation of cardiac cells
Influx of Ca 2+
Repolarisation of cardiac cells
Outflux of K+
Hyperkalaemia ECG findings
ST elevation
Tall tented T waves
Long PR
Wide QRS
Hypokalaemia ECG findings
Depressed ST segment
Inverted T wave
Hypercalcaemia ECG findings
Short QT
Short ST
Hypocalcaemia ECG findings
Prolonged QT
Prolonged ST
