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
