shock

SHOCK

Dr Begashaw M (MD)

Introduction

• is a life-threatening condition• occurs when the circulatory system fails to

deliver oxygen and nutrients to the body tissues & becomes unable to remove waste products

• may rapidly progress to an irreversible state with subsequent multi-organ failure and death

DEFINITION

• a pathological state causing inadequate oxygen delivery to the peripheral tissues and resulting in lactic acidosis, cellular hypoxia & disruption of normal metabolic condition

CLASSIFICATION

1. Hypovolemic 2. Cardiogenic 3. Obstructive4. Distributive - Septic shock - Neurogenic shock - Anaphylactic shock

Shock• Hypovolemic

– Hemorrhage– Anemia– Fluid loss

• Obstructive– Aortic valve stenosis

• Distributive– Sepsis– Thyrotoxicosis– Anaphylaxis

• Cardiogenic– Decompensated CHF– Acute coronary syndrome– Dysrhythmia – Myocarditis

Cardiogenic•CHF•ACS•Dysrhythmia

Distributive•Sepsis•ThyrotoxicosisObstructive•Aortic valve stenosis

Hypovolemic•Hemorrhage•Anemia

Preload

Afterload

InotropyShock

MAP = (SV x HR) x SVR

Preload

Afterload

Contractility

Arterialpressure

Cardiacoutput

Peripheralresistance

Heartrate

Strokevolume

Leftventricular

size

Myocardialfiber

shortening

Cardiac Performance

Cardiovascular & metabolic characteristics of shock

Hypovolemic shock

• inadequate vascular volume• results from loss of fluid from circulation, either

directly or indirectlyE.g▪ Hemorrhage• Loss of plasma due to burn• Loss of water & electrolytes in diarrhea• Third space loss

Where do pt bleed enough to die?

• Remember, there are only 5 places into which a person can bleed enough to cause hemodynamic instability– Chest– Peritoneum– Retroperitoneum– Thighs– World

Not the mediastinum

Cardiogenic shock

• impaired cardiac function• myocardial infarction • pericardial tamponade

Obstructive Shock

• Resistance to cardiac outflow– ↑ afterload– Aortic stenosis– Tension pneumothorax

Septic Shock (vasogenic shock)

• as a result of the systemic effect of infection• result of a septicemia with endotoxin and

exotoxin release by gram-negative and gram-positive bacteria

• impaired extraction as a result of impaired metabolism

Neurogenic shock

• disruption of the sympathetic nervous system

- to pain - loss of sympathetic tone, as in spinal cord

injuries

PATHOPHYSIOLOGY OF SHOCK

• stimulates a physiologic response - conserve perfusion to the vital organs (heart

and brain) - vasoconstriction of skin, splanchnic & renal

vessels leads to renal cortical necrosis and acute renal failure

Hypovolemic shock: physiology

• Reduced blood volume• Reduced preload• Reduced stroke volume• Reduced cardiac output Response to shock - physiology

– Cathecholamines , ADH– Vasoconstriction, tachycardia– Improve venous return and CO

CLINICAL FEATURES

• Tachycardia• Feeble pulse• Narrow pulse pressure• Cold extremities (except septic shock)• Sweating, anxiety• Breathlessness / Hyperventilation• Confusion leading to unconscious state

ClassParameter I II III IV

Blood loss (ml) <750 750–15001500–2000 >2000

Blood loss (%) <15% 15–30% 30–40% >40%Pulse rate (beats/min) <100 >100 >120 >140

Blood pressure Normal Decreased Decreased Decreased

Respiratory rate (breaths/min) 14–20 20–30 30–40 >35

Urine output (ml/hour) >30 20–30 5–15 Negligible

Mental status Normal Anxious Confused Lethargic

Classification of Hemorrhage

MANAGEMENT OF SHOCK

• restoring oxygen delivery to the cells of vital organs

General Management

Priority-ABC• Stop bleeding• Fluid resuscitation-crystalloids• Head down position-flat • Transfusion• Oxygen , inotropic • Monitoring -determine hourly urine output, BP,

pulse rate

Specific Management

Hypovolemic Shock• Restore vascular volume• Fluid and blood replacement• Oxygen support

Specific Management

Septic Shock• antibiotics• Inotropic –adrenaline,dopamine• Surgical eradication of the infection focusCardiogenic shock• InotropesNeurogenic shock• Pain relief• Treat the causes, give supportive measures - inotropic support

COMPLICATIONS OF SHOCK

1. Shock lung (ARDS)2. Acute renal failure3. Gastrointestinal ulceration4. Disseminated intravascular coagulation5. Multiorgan failure6. Death

Questions?