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Week 1: Shock

Updated: Feb 13

CCM Shock

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)

Renal response

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?

Examination

Observations


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%)

Hypovolaemic 16%

Obstructive 3%

What are the investigations for shock?

Bloods:

Lactate, ABG, Glucose

FBC, UEC, LFT

Coagulation (DIC Septic Shock)

Pressures:

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)

PAWP

CO:

CO/CI (Measured with Ficks Principle, Dilutional Technique)

MvO2 (Is a marker of tissue oxygenation, Ficks Law + can determine CO

Imaging:

TTE

CXR

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?

Hypovolaemic:

Haemorrhagic:

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)

Normothermia

Lethal Triad (Coagulopathic, Hypothermic, Acidotic)

Consider Vasopressor if ongoing hypotension with adequate

fluid/product resuscitation

Non haemorrhagic:

Fluid resuscitate (20 mL/kg boluses ~ 500 mL)

Vasopressor

Obstructive:

Pulmonary Embolism

Massive PE, Submassive PE

Thrombolysis (Alteplase, Tenecteplase)

Pulmonary Endarterectomy

Endovascular thrombolysis

VA ECMO

Pericardial Effusion

Pericardiocentesis

US guided

Tension Pneumothorax

Surgical decompression

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?

Impella

IABP

VA ECMO


Distributive: (Fluids + Pressor)

Sepsis

Fluids + Vasopressor and Antibiotics

Anaphylaxis

Fluids + Adrenaline

Neurogenic

Fluids + Vasopressor (Norad/Metaraminol)

SIRS

Fluids + Vasopressor

Endocrine

Addisonian crisis

Fluids

Steroids

Glucose

Monitor Hyperkalaemia

Myxedema

Thyroxine



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