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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 shock Basic principles in management of shock. Shock. - PowerPoint PPT Presentation
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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