Shock Shock General Surgery Orientation Medical Student Lecture Series Dr. Peter Meade.

ShockShock

General Surgery OrientationGeneral Surgery OrientationMedical Student Lecture SeriesMedical Student Lecture Series

Dr. Peter MeadeDr. Peter Meade

SHOCK

SHOCK

Burning building Desert

SHOCK

Lack of Oxygen Delivery

Low blood pressure

Decreased perfusion of tissues with Oxygen

Inflammatory Response

Cell Damage

SHOCKLack of Oxygen Delivery

(Hypoperfusion)

Cellular Damage

Inflammatory Response

Hypoperfusion causes Inflammation

Inflammation causes Hypoperfusion

What causes….

SHOCK

SHOCK

Most common forms in surgery:

Hypovolemic

Septic

Cardiogenic

SHOCK

Lack of Oxygen Delivery

(Hypoperfusion)

HypovolemiaBleeding / Hemorrhage

Vomiting

Pancreatitis

Burns

Trauma

Hypoperfusion causes Inflammation

Inflammation causes Hypoperfusion

SHOCK HYPOVOLEMIC

hemorrhagic

SHOCK HYPOVOLEMIC

Non-hemorrhagic fluid losses

Open wounds Burns- incredible fluid losses !

SHOCK:SEPTIC: Endotoxins from bacteria = Shock!

SHOCK

Lack of Oxygen Delivery(Hypoperfusion)

Septic

Septicemia, Endotoxins, Vasodilatation, pneumonia,

urinary tract infection, dead intestine, necrotic tissue

Hypoperfusion causes Inflammation

Inflammation causes Hypoperfusion

SHOCK CARDIOGENIC

Pump Failure Cardiogenic Shock

SHOCKLack of Oxygen

Delivery(Hypoperfusion)

Cardiogenic

Acute Myocardial infarctionAortic or mitral valve dysfunction

DysrhythmiaCardiac contusion

Massive Pulmonary embolismCardiac Tamponade

Congestive Heart Failure

Hypoperfusion causes Inflammation

Inflammation causes Hypoperfusion

SHOCKLack of Oxygen Delivery

(Hypoperfusion)

Cellular Damage

Inflammatory Response

Hypoperfusion causes Inflammation

Inflammation causes Hypoperfusion

Inflammatory Response

• Vasoconstriction

• Vasodilation

• Capillary leak– Nitric Oxide, PG2, kinins, histamine serotonin

• White Cells/ Polymorphonuclear cells– Phagocytosis: proteases, Interleukins

Inflammatory Response

Platelet Activation

PDGF

TGF-B

WBC Products

P-seletin

E-selectin

ICAM 1

WBC Proteases

IL-1, IL8

TNF

The Inflammatory ResponseIt can be like using a machine gun to kill a fly on the wall….

You might get the fly, but the wall gets hit too!

Hypoperfusion

• Anaerobic glycolysis

• Lactic Acidemia– Low bicarbonate– Low pH

• Multisystem Organ Failure

Krebs Cycle

36 ATPs

Anaerobic glycolysis

2 ATPs

Burning glucose without Oxygen = lactic acidosisBurning wet sticks = smoke

TREATMENT OF SHOCK

Treat the primary cause

“Source Control”

Hemorrhagic / Hypovolemic– Stop the bleeding– Replace blood loss, volume

Septic– Drain the abscess– Treat with antibiotics, volume, pressor agents

Starling Curve

• Preload

• Contractility

• Afterload

Starling Curve

• Preload

• Contractility

• Afterload

Hypovolemic Shock

Loss of circulating blood volume (Plasma)

Normal Blood Volume:

- 7% IBW in adults

- 9% IBW in children

Hypovolemic Shock

Hemorrhagic shock (3 categories)

1. Compensated:– 0-20% of blood loss

– Blood pressure is maintained – increased vascular tone – increased blood flow to vital organs

Hypovolemic Shock

The body’s response:

Compensated shock Baroreceptor mediatedvasoconstriction

Increased epinephrine, vasopressin, angiotensin

Results in:TachycardiaTachypneaLowered pulse pressureSlightly lowered urine output

Hypovolemic Shock

The Organs who win:BrainHeartKidneysLiver

The Organs who lose:SkinGI tractSkeletal Muscle

Hypovolemic Shock

But why

The body will make whatever adjustsments it can to maintain….

AdequateCardiacOutput

Brain and heart perfusions remain near normal less critical organ systems stressed by ischemia..

Hypovolemic Shock

2. Uncompensated:

20-40% loss of blood volume

Decrease in BP

Tachycardia

Hypovolemic Shock

The body’s response:

Uncompensated shock

vasoconstrictive mechanisms

FAIL to maintain systemic perfusion pressure.

• Increased cardiac output• Increased respiration• Sodium retention

Hypovolemic Shock

3. Lethal exsanguination: 40% loss of blood volume

Profound hypotension and inability to perfuse vital organs

Hypovolemic Shock

Volume Resuscitation ~ What are my goals?

1. Rapid Responder– Give 500cc-1 Liter crystalloid rapid

improvement of BP/HR/Urine output– < 20% blood loss– Surgery consult

Hypovolemic Shock

Volume Resuscitation ~ What are my goals?

2.Transient Responder– 500cc-1 Liter crystalloid improves briefly then deteriorates

– 20-40% blood loss– Continue crystalloid infusion +/- Blood– Surgery consult

Hypovolemic Shock

Volume Resuscitation ~ What are my goals?

3. Non Responder– Give 2 Liters crystalloid/ 2 units Blood no

response– > 40% blood loss– STAT Surgery consult!

Hypovolemic Shock

Is my volume resuscitation adequate/inadequate?

Urine output Vital signsSkin perfusionPulse OximetryAcidemia

Septic Shock

exaggerated endogenous inflammatory response to invasive infection leading to:

-circulatory collapse

-multiple organ failure

-death

Septic Shock

Mortality

over 35% (sepsis with hypotension)

45% (sustained septic shock)

Septic ShockManagement:Identify and treat the infectious source

eg – simple incision & drainage? Exploratory laparotomy?

Amputation?

Volume resuscitation

Restoration of perfusion pressure (may need pressors!)

Cardiogenic Shock

Acute hypotension

low cardiac output

inadequate LV outflow

Poor end organ perfusion!

Cardiogenic Shock

Causes most likely to see on the surgery wards:Causes most likely to see on the surgery wards:

Acute MIAcute MI

Arrhythmia (A. fib)Arrhythmia (A. fib)

Cardiac Contusion Cardiac Contusion

Cardiac TamponadeCardiac Tamponade

Massive Pulmonary EmbolismMassive Pulmonary Embolism

Decompensated Congestive Heart FailureDecompensated Congestive Heart Failure