Shock

Definition

SHOCK: inadequate organ perfusion to meet the tissue’s

oxygenation demand.

Three major types of shock Hypovolemic shock

» Decreased intravascular volume resulting form loss of blood, plasma, or fluids and electrolytes

Cardiogenic shock

» Pump failure due to myocardial damage or massive obstruction of outflow tracts

Distributive shock

» Reduction of vascular resistance form

Sepsis

Anaphylaxis

Systemic inflammatory response syndrome (SIRS)

Cardiogenic Shock

Cardiogenic Shock

Diminished cardiac output leading to impaired tissue

perfusion

Most extreme form of pump failure

Cardiogenic Shock

Occurs in about 15% of acute MI patients

Usually occurs when 40% or more of the left ventricular muscle mass infarcts

Mortality is 85% or more with treatment

Etiologies Acute myocardial

infarction/ischemia

LV failure

Papillary muscle/chordalrupture- severe MR

Ventricular free wall rupture with subacutetamponade

Other conditions complicating large MIs

» Hemorrhage

» Infection

» Excess negative inotropic or vasodilator medications

» Prior valvular heart disease

» Hyperglycemia/ketoacidosis

» Post-cardiac arrest

» Post-cardiotomy

» Refractory sustained tachyarrhythmias

» Acute fulminantmyocarditis

» End-stage cardiomyopathyHypertrophic cardiomyopathy with severe outflow obstruction

» Aortic dissection with aortic insufficiency or tamponade

» Pulmonary embolu

» Severe valvular heart disease -Critical aortic or mitral stenosis, Acute severe aortic or MR

Pathophysiology

Characteristics of Cardiogenic Shock

Low cardiac output

Peripheral vasoconstriction

Left sided heart failure leads to pulmonary venous congestion and pulmonary edema

Right sided heart failure leads to systemic venous congestion and peripheral edema

It is essential to distinguish a cardiogenic from a hypovolemic

shock!Both forms are associated with reduced cardiac out put, and increased peripheral

vascular resistance, however:

Cardiogenic shock:

jugular venous distention (high

CVP)

Hypovolemic shock: collapsed capacitance veins (low CVP)

Signs/Symptoms

Confusion, restlessness, anxiety, stupor, coma

Cool, clammy skin

Pallor

Weak or absent extremity pulses

Tachycardia

Slow or absent capillary refill

Signs/Symptoms

BP < 90 systolic or > 30mmHg below normal

»BP is NOT the same as perfusion

» Shock can be present with a “normal” BP

»Evaluate signs of peripheral perfusion in addition to BP

Cardiogenic Shock

Treatment Priorities:

»Rate

»Rhythm

»BP (Volume, Pump/Vascular tone)

Correct major disorders of rate, rhythm before directly treating BP

Goals of Management

Improve oxygenation and peripheral perfusion

Avoid increasing cardiac workload

»myocardial oxygen demand

Management

Primary assessment & Focused Hx

Identify source of problem

»Acute pulmonary edema

»Volume problem

»Pump problem

»Rate problem

Acute Pulmonary Edema

First line interventions

» IV/O2/ECG Monitor

» If BP > 90-100 mm Hg:

furosemide 0.5 – 1.0 mg/kg slow IV (or twice patient’s single daily dose up to 120 mg)

Morphine 2 – 10 mg slow IV

Nitroglycerin 0.4 mg SL

» If BP < 90 mm Hg:

Vasopressors based on SBP

Volume Problem

IV/O2/ECG Monitor

Fluid challenge until rales or if evidence of anterior wall AMI

Vasopressors based on SBP

Pump Problem

IV/O2/ECG Monitor

SBP 100 mm Hg w/o shock

» dobutamine 2 – 20 mcg/kg/min IV inf

Management

If rate/rhythm adequate, treat BP

»Consider fluid challenge of 250cc LR over 10-15 minutes if relative or absolute hypovolemia possible, including RVF and NO pulmonary edema

»Avoid use of vasopressors until volume deficits corrected or pulmonary edema presents

BP Treatment Review

If rate, rhythm, volume adequate, treat BP with vasopressors:

»Norepinephrine, or

»Dopamine

Norepinephrine

0.5 - 30 mcg/min

Inotropic and vasoconstrictive properties

Can be used if systolic BP < 70

If systolic BP > 70, use dopamine instead

DO NOT use until hypovolemia corrected

DO NOT allow infiltration

Dopamine2 - 20 mcg/kg/min

» Place 200 mg/250cc of D5W

» Begin at 5 mcg/kg/min

» In 2 - 10 mcg/kg/min range, effects dominate

» > 20 mcg/kg/min effects dominate

» Use lowest dose that produces good perfusion

Use as initial vasopressor if BP 70-100 systolic

» If dopamine infusion rate is > 20 mcg/kg/min use norepinephrine

Dopamine

May cause tachycardia, ectopy, nausea

DO NOT use until hypovolemiais corrected

Distributive Shock

Distributive Shock

Reduced peripheral vascular tone leads to pooling of blood in extremities poor venous return

Physical exam depends on stage

» Early: Warm extremities, wide pulse pressure, low diastolic pressure

» Late: perfusion pressure falls and acidosis develops

Distributive Shock

Sepsis

» Due to gram negative or gram positive bacteria

Anaphylaxis

» Due to previous sensitization to an allergen

Neurogenic

» Due to traumatic spinal cord injury

» Effects of epidural or spinal anesthetics

» Reflex parasymapthetic stimulation

Bacteremia, SIRS, Sepsis

Bacteremia: an identifiable organism cultured from the blood

Systemic Inflammatory Response Syndrome (SIRS): sepsis without organism identified. Meet at least 2 of criteria:

» Hypo or hyperthermia

» Tachycardia or bradycardia

» Tachypnea

» Leukocytosis or leukopenia

Sepsis: SIRS from a systemic illness (bacterial, viral, protozoal)

Pathogenesis of Septic Shock(vasodilatory shock)

Sepsis is defined as a systemic inflammatory response to a bacterial infection with bacteriemia(though blood cultures can be negative)

Severe sepsis is defined by additional end-organ dysfunction (mortality rate: 25-30%)

Septic shock is defined as sepsis with hypotension despite fluid resuscitation and evidence of inadequate tissue perfusion (40-70%)

NEJM 2004, Vol. 351;2 pp 159-169

The syndrome of septic shock is characterized by

Systemic vasodilation (hypotension)

Diminished myocardial contractility

Widespread endothelial injury and activation leading to fluid leakage (capillary leak) resulting in acute respiratory distress syndrome (ARDS)

Activation of the coagulation cascade (DIC)

Septic Shock Early “Warm Shock”

↑ CO and ↓ SVR and wide pulse pressure

Signs: warm extremities, flushing, bounding pulses, ↑ HR, confusion

Hypocarbia, elevated lactate, hyperglycemia

Late “Cold Shock”

Uncompensated shock with drop in CO

Signs: cyanosis, cold, clammy skin, threadypulse, shallow respiration

Metabolic acidosis, hypoxia, coagulopathy, hypoglycemia

S/S of Septic Shock

Increased to low blood pressure

High fever, no fever, hypothermic

Skin flushed, Pale, Cyanotic

Difficulty breathing and altered lung sounds

TX of Septic Shock

Airway control

Administer oxygen

IV of crystalloid solution

Dopamine for blood pressure support

Monitor other vitals

Anaphylatic Shock

Severe immune response to foreign substance

S/S most often occur within minutes but can take up to hours to occur

The faster the reaction develops the more severe it is likely to be

Death will occur if not treated promptly

S/S of Anaphylactic Shock

Skin

- Flushing

- Itching

- Hives

-Swelling

-Cyanosis

S/S of Anaphylactic Shock

Respiratory System

- Breathing difficulty

- Sneezing, Coughing

- Wheezing, Stridor

- Laryngeal edema

- Laryngospasm

S/S of Anaphylactic Shock

Cardiovascular System

- Vasodilation

- Increased heart rate

- Decreased blood pressure

S/S of Anaphylactic Shock

Gastrointestinal System

- Nausea, vomiting

- Abdominal cramping

- Diarrhea

TX for Anaphylactic Shock

Airway protection which may include Endotracheal Intubation

Establish IV with crystalloid solution

Pharmacological interventions: Epinephrine, Antihistamines(Benadryl), Corticosteroids(dexamethasone), Vasopressors(dopamine, Epinephrine), and inhaled beta agonist(albuterol)