Updated: Feb 13
Tutorial 1: Summary
What is Shock?
Inadequate tissue perfusion, inadequate oxygen supply
Normal BP does not rule out Shock
SIRS does not always equal Shock
What is the pathophysiology of shock?
Ohms law V=IR (Voltage = Current x Resistance)
BP = CO x SVR
CO = SV x HR
SV = Preload, Afterload, Inotropy (Frank-Starling Curve)
SVR = Poiseuille's law = vL/r^4 (v = viscosity, L = length of vessel, r = radius)
Baroreceptor response (Carotid/Ao Arch)
Regional circulation response (Metabolic, myogenic)
What are the stages of Shock?
1. Compensatory (Baroreceptor, Noradrenaline, RAAS, HR, Tachypnoea)
2. Progressive/Decompensated. (MODS, 2 or more organs)
3. Refractory (Shock can no longer can be reversed, organ death occurs)
What are the clinical signs of Shock?
Why do we get poor UO, ALOC, and impaired Liver function?
Brain CO 15%, VO2 20%
Kidney CO 25%, VO2 7%
Liver CO 30%, VO2 20%
What are the 4 classes of shock?
Cardiogenic (Arrhythmia, Ischaemic, Mechanical, Cardiomyopathy, Toxin)
Obstructive (Pulmonary Vascular, Mechanical)
Hypovolaemic (Haemorrhagic (Stages 1-4), Non Haemorrhagic)
Distributive (Neurogenic, Septic, SIRS, Endocrine, Anaphylaxis)
What is the prevalence of shock in ICU?
Distributive 60% (Sepsis)
Cardiogenic 16% (AMI 70%)
What are the investigations for shock?
Lactate, ABG, Glucose
FBC, UEC, LFT
Coagulation (DIC Septic Shock)
MAP (1/3 Systole, 2/3 Diastole, AUC Art line)
Pulse Pressure (Normal 40, Narrow < 20, Raised > 60) (Increases with age > 55)
CVP (Can be used as a marker of fluid status when giving fluids,
SVR (Product of CVP, MAP, CO)
CO/CI (Measured with Ficks Principle, Dilutional Technique)
MvO2 (Is a marker of tissue oxygenation, Ficks Law + can determine CO
CT CAP/PXR/Long bones/eFAST
How do we differentiate shock?
Clinical history + Examination
Warm vs Cold shock
Parameters (CO, SVR, PAWP/LVEDV, MvO2)
There will be combinations of Shock
Severity: SOFA Score (Sequential Organ Failure Assessment Score)
How do we treat shock?
Find and Stop the bleeding
Blood products (MTP, 2:1:1/1:1:1)
Fluid CSL > NaCL (nil secondary NAGMA)
Permissive Hypotension MAP >=65, SBP 80 - 100
Unless TBI (MAP > 80, SBP > 90)
Lethal Triad (Coagulopathic, Hypothermic, Acidotic)
Consider Vasopressor if ongoing hypotension with adequate
Fluid resuscitate (20 mL/kg boluses ~ 500 mL)
Massive PE, Submassive PE
Thrombolysis (Alteplase, Tenecteplase)
Finger thoracotomy bedside
Cardiogenic: (Complicated, treat the cause)
Is the patient wet or dry?
What is the cause of cardiogenic shock?
70% of Cardiogenic shock is due to AMI, is there AMI
Treat the cause
Does noradrenaline need to be started?
If MAP < 65 Norad advised, no point worrying about afterload if you cant perfuse your coronaries
Aim MAP ~ 65
Should I use an Inodilator like Dobutamine instead
Is mechanical support required?
Distributive: (Fluids + Pressor)
Fluids + Vasopressor and Antibiotics
Fluids + Adrenaline
Fluids + Vasopressor (Norad/Metaraminol)
Fluids + Vasopressor