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SHOCK

Prof.M.H.MUMTAZ

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SHOCK

Inadequate perfusion (blood flow) leading to inadequate oxygen delivery to tissues

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Physiology

Basic unit of life = cell Cells get energy needed to stay

alive by reacting oxygen with fuel (usually glucose)

No oxygen, no energy No energy, no life

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Aerobic Metabolism

6 O2

GLUCOSE

METABOLISM

6 CO2

6 H2O

36 ATP

HEAT (417 kcal)

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Anaerobic Metabolism

GLUCOSE METABOLISM

2 LACTIC ACID

2 ATP

HEAT (32 kcal)

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Anaerobic? So What?

InadequateInadequateCellularCellular

OxygenationOxygenation

InadequateInadequateCellularCellular

OxygenationOxygenation

AnaerobicAnaerobicMetabolismMetabolism

AnaerobicAnaerobicMetabolismMetabolism

MetabolicMetabolicFailureFailure

MetabolicMetabolicFailureFailure

MetabolicMetabolicAcidosisAcidosis

MetabolicMetabolicAcidosisAcidosis

InadequateInadequateEnergyEnergy

ProductionProduction

InadequateInadequateEnergyEnergy

ProductionProduction

Lactic AcidLactic AcidProductionProduction

Lactic AcidLactic AcidProductionProduction

Cell Death!Cell Death!Cell Death!Cell Death!

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Homeostasis is maintenance of balance

Requires proper functioning systems• Cardiovascular• Respiratory• Renal

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Cardiovascular System

Transports oxygen, fuel to cells Removes carbon dioxide, waste

products for elimination from body

Cardiovascular system must be able to maintain sufficient flow through

capillary beds to meet cell’s oxygen and fuel needs

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Flow = Perfusion

Adequate Flow = Adequate Perfusion

Inadequate Flow = Indequate Perfusion

(Hypoperfusion)

Hypoperfusion = Shock

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What is needed to maintain perfusion?

Pump Pipes Fluid

Heart

Blood VesselsBlood

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How can perfusion fail?

Pump Failure Pipe Failure Loss of Volume

Factors Affecting The Pump

Factors Affecting The Pump

Preload Contractile force

• Frank-starling mechanism Afterload

Preload Contractile force

• Frank-starling mechanism Afterload

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Muscle Anatomy

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Contraction: Sliding Filaments

image from: http://www.accessexcellence.com/AB/GG/muscle_Contract.html

What Is Blood Pressure?What Is Blood Pressure?

BP = COxSVR

BP = COxSVR

CO = Stroke VolumeCO = Stroke VolumeX Heart RateX Heart Rate

SVR= B.vessel calibre +viscositySVR= B.vessel calibre +viscosity

CO = Stroke VolumeCO = Stroke VolumeX Heart RateX Heart Rate

SVR= B.vessel calibre +viscositySVR= B.vessel calibre +viscosity

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What Affects Blood Pressure?

ANS balance Contractility

• Preload• Starling’s law

Afterload

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Types of Shock and Their Causes

CARDIOGENICHYPOVOLAEMIC

SEPTICNEUROGENICPSYCHOGENic

obstructiveANAPHYLACTIC

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Cardiogenic Shock

Pump failure Heart’s output depends on

• How often it beats (heart rate)• How hard it beats (contractility)

Rate or contractility problems cause pump failure

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Cardiogenic Shock

Causes• Acute myocardial infarction• Very low heart rates (bradycardias)• Very high heart rates (tachycardias)

Why would a high heart rate caused decreased output?

Hint: Think about when the heart fills.

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Neurogenic Shock

Loss of peripheral resistance Spinal cord injured Vessels below injury dilate

What happens to the pressure in a closed system if you increase its size?

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Hypovolemic Shock

Loss of volume Causes

• Blood loss: trauma• Plasma loss: burns• Water loss: Vomiting, diarrhea, sweating,

increased urine, increased respiratory loss

If a system that is supposed to be closed leaks, what happens to the pressure in it?

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Psychogenic Shock

Simple fainting (syncope) Caused by stress, pain, fright Heart rate slows, vessels dilate Brain becomes hypoperfused Loss of consciousness occurs

What two problems combine to produce hypoperfusion in psychogenic shock?

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Septic Shock

Results from body’s response to bacteria in bloodstream

Vessels dilate, become “leaky”

What two problems combine to produce hypoperfusion in septic shock?

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Anaphylactic Shock

Results from severe allergic reaction Body responds to allergen by releasing

histamine Histamine causes vessels to dilate and

become “leaky”

What two problems combine to produce hypoperfusion in anaphylaxis?

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OBSTRUCTIVE SHOCK

PUMONARY EMBOLISM ?

CRDIAC TEMPONADE ?

PNEUMOTHORAX ?

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Shock:Signs and Symptoms

Restlessness, anxiety

Decreasing level of consciousness

Dull eyes Rapid, shallow

respirations

Why are these signs and symptoms present? Hint: Think hypoperfusion

Nausea, vomiting Thirst Diminished urine

output

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Shock: Signs and Symptoms

Hypovolemia will cause• Weak, rapid pulse• Pale, cool, clammy skin

Cardiogenic shock may cause:• Weak, rapid pulse or

weak, slow pulse• Pale, cool, clammy skin

Neurogenic shock will cause:• Weak, slow pulse• Dry, flushed skin

Sepsis and anaphylaxis will cause:• Weak, rapid pulse• Dry, flushed skin

Can you explain the differences in the signs and symptoms?

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Shock: Signs and Symptoms

Patients with anaphylaxis will:• Develop hives (urticaria)• Itch• Develop wheezing and difficulty

breathing (bronchospasm)

What chemical released from the body during an allergic reaction accounts for these effects?

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Shock: Signs and Symptoms

Shock is NOT the same thing as a low blood pressure!

A falling blood pressure is a LATE sign of shock!

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Treatment

Secure, maintain airway Apply high concentration oxygen Assist ventilations as needed Keep patient supine Control obvious bleeding Stabilize fractures Prevent loss of body heat

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Treatment

Elevate lower extremities 8 to 12 inches in hypovolemic shock

Do NOT elevate the lower extremities in cardiogenic shock

Why the difference in management?

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Management of Shock

Shock begins when DO2 to the cells is inadequate to meet metabolic demand

The major therapeutic goals in shock therefore are sufficient tissue perfusion and oxygenation

Early diagnosis remains a major problem

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Treatment

Administer nothing by mouth, even if the patient complains of thirst

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Hemodynamic Characteristics in Different Types of Shock

Type Preload CO PVR SVR

Hemmorrhagic LOW

Anaphylactic LOW

Cardiogenic HIGH

Septic (Hyperdynamic)

LOW

Septic (Hypodynamic)

LOW

/

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Inotropic Agents and Vasodilators

Vasoactive drugs are an important pharmacologic defense in the treatment of shock.

May be required to support BP in the early stages of shock.

These agents may be needed to:• Enhance CO through the use of inotropic

agents• Increase SVR through the use of vasopressors

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Effects of Inotropic Agents and Vasodilators

Epinephrine 0.02 – 0.5

Norepinephrine

0 - 0.05 – 0.5

Dopamine DR 2 -12

Dobutamine

2 - 12

Dopexamine

DR 0 - 0.9 - 5

Vasopressin Angiotensin III

5 - 20

Amrinone PDI 5 -10

Drug Receptor CO SVR Dose Range

0 -

(g/kg/min)

1

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Effects of Inotropic Agents and Vasodilators

Nifedipine 0 - 0.5 - 10

Nitroglycerin 0 - 3 - 5

Nitroprusside 0 - 0.5 - 5

Prostacyclin 10 - 40

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Drug CO SVR Dose Range

(g/kg/min)

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Dopamine An endogenous precursor of norepinephrine with

multiple dose-related effects

Low Dose (0.5 - 3 mg/kg/min)2 and dopaminergic (DR) effects

• Enhanced blood flow to renal and splanchnic beds

Moderate Dose (5 -10 mg/kg/min)• Positive inotropic effects

High Dose (>20 mg/kg/min)-actions (vasoconstriction)

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MANAGEMENT GUIDE

1,Haemodynamic monitoring Blood pressure/HR SV,HR,CI,CO SVR,SVRI TOOLS ; SWAN GANZ TEMPERATURE LIDCO CENTRAL VENOUS PRESSURE

2, OXYGENATION STATUS FIO2/PAO2/PaO2/DO2/VO2/ Lactate

3, ACID BASE STATUS

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HAEMODYNAMIC TRUTHS

1,TACHYCARDIA IS NEVER AGOOD THING. 2,HYPOTENSION IS ALWAYS PATHOLOGIC 3,THERE IS NO SUCH THING AS NORMAL CARDIAC OUTPUT. 4,CENTRAL VENOUS PRESSURE IS ONLY ELEVATED IN DISEASE. 5,PERIPHERA EDEMA IS OF COSMETIC

CONCERN.

PINKSY..Chest.2007; 132;2020-2029

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Bleeding

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Bleeding Significance

If uncontrolled, can cause shock and death

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Identification of External Bleeding

Arterial Bleed • Bright red• Spurting

Venous Bleed• Dark red• Steady flow

Capillary Bleed• Dark red

• Oozing

What is the physiology that

explains the differences?

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Control of External Bleeding

Direct Pressure• gloved hand• dressing/bandage

Elevation Arterial pressure points

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Arterial Pressure Points

Upper extremity: Brachial Lower extramity: Femoral

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Control of External Bleeding

Splinting• Air splint• Pneumatic antishock garment

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Control of External Bleeding

Tourniquets• Final resort when all else fails• Used for amputations• 3-4” wide• write “TK” and time of application on

forehead of patient• Notify other personnel

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Control of External Bleeding

Tourniquets• Do not loosen or remove until

definitive care is available• Do not cover with sheets, blankets,

etc.

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Epistaxis

Nosebleed Common problem

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Epistaxis

Causes• Fractured skull• Facial injuries• Sinusitis, other URIs• High BP• Clotting disorders• Digital insertion (nose picking)

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Epistaxis

Management • Sit up, lean forward• Pinch nostrils together• Keep in sitting position• Keep quiet• Apply ice over nose• 15 min adequate

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Epistaxis

Epistaxis can result in life-threatening blood loss

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Internal Bleeding

Can occur due to:• Trauma• Clotting disorders• Rupture of blood vessels• Fractures (injury to nearby vessels)

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Internal Bleeding

Can result in rapid progression to hypovolemic shock and death

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Internal Bleeding

Assessment• Mechanism?• Signs and symptoms of hypovolemia

without obvious external bleeding

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Internal Bleeding

Signs and Symptoms•Pain, tenderness, swelling,

discoloration at injury site•Bleeding from any body orifice

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Internal Bleeding

Signs and Symptoms• Vomiting bright red blood or coffee

ground material• Dark, tarry stools (melena)• Tender, rigid, or distended abdomen

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Internal Bleeding

Management• Open airway• High concentration oxygen• Assist ventilations• Control external bleeding• Stabilize fractures• Transport rapidly to appropriate facility