Shock Dr.Hadeel AlOtair ABIM,MRCP,FCCP

Outline

Definition & mechanism of shock.Consequences of Shock.How to diagnose shock? Classification of Shock.Causes of various types of shockBasic principles in management of shock.

Shock

Reduction of effective tissue perfusion leading to cellular and circulatory dysfunction

Shock

The Aim of perfusion is to achieve adequate Cellular OxygenationThis requires :

Red Cell OxygenationRed Cell Delivery To Tissues

Fick Principle

Fick Principle

Air’s gotta go in and out.Blood’s gotta go round and round.Any variation of the above is not a

good thing!

Shock

Red Cell Oxygenation

Oxygen delivery to alveoli

Adequate FiO2

Patent airwaysAdequate ventilation

Shock

Red Cell Oxygenation

Oxygen exchange with blood

Adequate oxygen diffusion into bloodAdequate RBC mass/Hgb levelsAdequate RBC capacity to bind O2

– pH– Temperature

Shock

Red Cell Delivery To Tissues

Adequate perfusionBlood volumeCardiac output

– Heart rate– Stroke volume (pre-load, contractility, after-load)

Conductance– Arterial resistance– Venous capacitance

ShockRed Cell Delivery To Tissues

Adequate RBC mass

Adequate Hgb levels

Adequate RBC capacity to unbind O2

pHTemperature

Consequencies of Shock

Inadequate oxygenation or perfusion causes:

Inadequate cellular oxygenationShift from aerobic to anaerobic

metabolism

ANAEROBIC METABOLISM

GLUCOSE METABOLISM

2 LACTIC ACID

2 ATP

HEAT (32 kcal)

Glycolysis: Inefficient source of energy production; 2 ATP for every glucose; produces pyruvic acid

AEROBIC METABOLISM

6 O2

GLUCOSE

METABOLISM

6 CO2

6 H2O

36 ATP

HEAT (417 kcal)

Glycolysis: Inefficient source of energy production; 2 ATP for every glucose; produces pyruvic acid

Oxidative phosphorylation: Each pyruvic acid is converted into 34 ATP

Anaerobic Metabolism

Occurs without oxygenoxidative phosphorylation can’t occur without oxygenglycolysis can occur without oxygencellular death leads to tissue and organ deathcan occur even after return of perfusion

organ dysfunction or death

InadequateCellularOxygenDelivery

AnaerobicMetabolism

InadequateEnergyProduction

MetabolicFailure

LacticAcidProduction

MetabolicAcidosisCELL

DEATH

Ultimate Effects of Anaerobic Metabolism

Shock

Markers Of Hypoperfusion

↑S.LactatePerfusion related acidemiaHypotension

Maintaining perfusion requires:

VolumePumpVessels

Failure of one or more of these causes shock

Shock SyndromesHypovolemic Shockblood VOLUME problem

Cardiogenic Shock Blood pump problem

ObstructiveShock Filling Problem

Distributive Shock blood VESSEL problem

Hypovolemic Shock( Loss of Volume)

blood loss Trauma:BLOOD YOU SEE BLOOD YOU DON’T SEE

Non-traumaticVaginalGIGU

Fluid loss (Dehydration)

–Burns_Diarrhea–Vomiting–Diuresis–Sweating

–Third space lossesPancreatitisPeritonitisBowel obstruction

Signs

Due to Hypoperfusion– Altered mental state– Impaired capillary filling– ↓Urine output– Skin temperature cold clammy– BP(narrow pulse pressure, Postural↓BP)– Low volume pulse– Skin colour:peripheral cyanosis

Compensatory responses _ Tachycardia, _ pallor

Key Issues In Shock

Recognize & Treat during compensatory phase

Best indicator of resuscitation

effectiveness = Level of Consciousness

Restlessness, anxiety, combativeness = Earliest

signs of shock

Hypovolemic Shock managementgoal: Restore circulating volume, tissue perfusion & correct cause

• Airway & Breathing• Control bleeding• Elevate lower extremities • Avoid Trendelenburg

Two large bore IV lines/central lineFluids / Blood & Products /vasopressors

Target arterial BP – SBP ≥ 90 mmHg - MAP ≥65 mmHg.

Bladder catheterArterial Cannulation

Key Issues In Shock

Tissue ischemic sensitivityHeart, brain, lung: 4 to 6 minutesGI tract, liver, kidney: 45 to 60 minutesMuscle, skin: 2 to 3 hours

Resuscitate Critical Tissues

First!

Consequence Of Volume Loss:

15%[750ml]- compensatory mechanism maintains cardiac output

15-30% [750-1500ml]-, decreased BP & urine output

30-40% [1500-2000ml] -Impaired compensation & profound shock along with severe acidosis

40-50% - refractory stage

Shock

Cardiogenic Shock = Pump Failure

MyopathicM ICHFCardiomyopathy

ArrhythmicTachy or bradyarrhythmias

–Mechanical Valvular Failure

HOCM

Cardiogenic Shock

History : Chest pain, Palpitations,SOB RHD,IHD

Physical exam:Signs of ventricular failureHeart:Murmurs,S3,S4

Cardiogenic Shock

Supine, or head and shoulders slightly elevated, do NOT elevate lower extremities

Treat the underlying cause if possible examples

Treat rate, then rhythm, then BP

Correct bradycardia or tachycardia Correct irregular rhythms Treat BP

↑Cardiac contractility(inotropes)– Dobutamine, Dopamine

Distributive Shock

Inadequate perfusion of tissues due to mal-distribution of blood flow

(blood vessels problem)Cardiac pump & blood volume are normal but blood is not reaching the tissues

Distributive Shock Septic Shock

Anaphylactic Shock Histamine is released

– Blood vessels» Dilate (loss of resistance)» Leak (loss of volume)

– Extravascular smooth muscle spasm» Laryngospasm» Bronchospasm

Neurogenic/Vasogenic(spinal cord)

Endocrinologic

Sepsis & Septic shock

Septic Shock management

A B C,Assist ventilation & Augment OxygenationMonitor Tissue perfusion-

Restore Tissue perfusion-

IVFluids, VasopressorsIdentification & Eradication of septic fociSpecific Therapies

-

Neurogenic Shock

Patient supine; lower extremities elevatedAvoid Trendelenburg Infuse isotonic crystalloid Maintain body temperature

Anaphylactic Shock

Suppress inflammatory responseAntihistaminesCorticosteroids

Oppose histamine responseEpinephrine

– bronchospasm & vasodilation

Replace intravascular fluidIsotonic fluid titrated to BP ~ 90 mm

Obstructive shock

Impaired diastolic fillingCardiac tamponadeConstrictive pericarditisTension pneumothorax

Increased ventricular afterload Pulmonary embolism

Obstructive Shock

Treat the underlying causeTension PneumothoraxPericardial Tamponadeanticoagulation

Isotonic fluids titrated to BP w/o pulmonary edemaControl airway

Intubation

Key Issues In Shock

Falling BP = LATE sign of shockBP is NOT same thing as perfusionPallor, tachycardia, slow capillary refill = hypoperfusion, until proven otherwise

Shock Management

Avoid vasopressors until hypovolemia ruled out, or

correctedSqueezing partially

empty tank can cause ischemia, necrosis of

kidney and bowel

Hypovolemic Shock:

Fluid loss: Dehydration Nausea & vomiting, diarrhea, massive diuresis, extensive burns

Blood loss: trauma: blunt and penetrating BLOOD YOU SEE BLOOD YOU DON’T SEE

Initial Management Hypovolemic Shock

goal: Restore circulating volume, tissue perfusion & correct cause

• Arrest ongoing blood loss

• Early Recognition- Do not relay on BP! (30% fld loss)• Restore circulating volume - IV fluids 1-2 ltr-Crystalloid VS Colloids - Blood & Products