Shock

Outline

 Definition

 Epidemiology

 Physiology

 Classes of Shock

 Clinical Presentation

 Management

 Controversies

Definition

 A physiologic state characterized by

 Inadequate tissue perfusion

 Clinically manifested by

 Hemodynamic disturbances

 Organ dysfunction

Epidemiology

 Mortality

 Septic shock – 35-40% (1 month mortality)

 Cardiogenic shock – 60-90%

 Hypovolemic shock – variable/mechanism

Pathophysiology

 Imbalance in oxygen supply and demand

 Conversion from aerobic to anaerobic metabolism

 Appropriate and inappropriate metabolic and physiologic responses

 Cellular physiology

 Cell membrane ion pump dysfunction

 Leakage of intracellular contents into the extracellular space

 Intracellular pH dysregulation

 Resultant systemic physiology

 Cell death and end organ dysfunction

 MSOF and death

 Characterized by three stages

 Preshock (warm shock, compensated shock)

 Shock

 End organ dysfunction

 Compensated shock

 Low preload shock – tachycardia, vasoconstriction, mildly decreased BP

 Low afterload (distributive) shock – peripheral vasodilation, hyperdynamic state

 Shock

 Initial signs of end organ dysfunction

 Tachycardia

 Tachypnea

 Metabolic acidosis

 Oliguria

 Cool and clammy skin

 End Organ Dysfunction

 Progressive irreversible dysfunction

 Oliguria or anuria

 Progressive acidosis and decreased CO

 Agitation, obtundation, and coma

 Patient death

Classification

 Schemes are designed to simplify complex physiology

 Major classes of shock

 Hypovolemic

 Cardiogenic

 Distributive

Hypovolemic Shock

 Results from decreased preload

 Etiologic classes

 Hemorrhage - e.g. trauma, GI bleed, ruptured aneurysm

 Fluid loss - e.g. diarrhea, vomiting, burns, third spacing, iatrogenic

 Hemorrhagic Shock

Cardiogenic Shock

 Results from pump failure

 Decreased systolic function

 Resultant decreased cardiac output

 Etiologic categories

 Myopathic

 Arrhythmic

 Mechanical

 Extracardiac (obstructive)

Distributive Shock

 Results from a severe decrease in SVR

 Vasodilation reduces afterload

 May be associated with increased CO

 Etiologic categories

 Sepsis

 Neurogenic / spinal

 Other (next page)

 Other causes

 Systemic inflammation – pancreatitis, burns

 Toxic shock syndrome

 Anaphylaxis and anaphylactoid reactions

 Toxin reactions – drugs, transfusions

 Addisonian crisis

 Myxedema coma

 Septic Shock

Clinical Presentation

 Clinical presentation varies with type and cause, but there are features in common

 Hypotension (SBP<90 or Delta>40)

 Cool, clammy skin (exceptions – early distributive, terminal shock)

 Oliguria

 Change in mental status

 Metabolic acidosis

Evaluation

 Done in parallel with treatment!

 H&P – helpful to distinguish type of shock

 Full laboratory evaluation (including H&H, cardiac enzymes, ABG)

 Basic studies – CxR, EKG, UA

 Basic monitoring – VS, UOP, CVP, A-line

 Imaging if appropriate – FAST, CT

 Echo vs. PA catheterization

 CO, PAS/PAD/PAW, SVR, SvO2

Treatment

 Manage the emergency

 Determine the underlying cause

 Definitive management or support

Manage the Emergency

 Your patient is in extremis – tachycardic, hypotensive, obtunded

 How long do you have to manage this?

 Suggests that many things must be done at once

 Draw in ancillary staff for support!

 What must be done?

 One person runs the code!

 Control airway and breathing

 Maximize oxygen delivery

 Place lines, tubes, and monitors

 Get and run IVF on a pressure bag

 Get and run blood (if appropriate)

 Get and hang pressors

 Call your senior/fellow/attending

Determine the Cause

 Often obvious based on history

 Trauma most often hypovolemic (hemorrhagic)

 Postoperative most often hypovolemic (hemorrhagic or third spacing)

 Debilitated hospitalized pts most often septic

 Must evaluate all pts for risk factors for MI and consider cardiogenic

 Consider distributive (spinal) shock in trauma

 What if you’re wrong?

 85 y/o M 4 hours postop S/P sigmoid resection for perforated diverticulitis is hypotensive on a monitored bed at 70/40

 Likely causes

 Best actions for the first 5 minutes?

Definitive Management

 Hypovolemic – Fluid resuscitate (blood or crystalloid) and control ongoing loss

 Cardiogenic - Restore blood pressure (chemical and mechanical) and prevent ongoing cardiac death

 Distributive – Fluid resuscitate, pressors for maintenance, immediate abx/surgical control for infection, steroids for adrenocortical insufficiency