Shock

By:Dawit AyeleMD,Internist

Definition Epidemiology Physiology Classes of Shock Clinical Presentation Management Controversies

Outline

A physiologic state characterized by◦ Inadequate tissue perfusion

Clinically manifested by◦ Hemodynamic disturbances◦ Organ dysfunction

Definition

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

◦ Cardiogenic shock – 60-90%

◦ Hypovolemic shock – variable/mechanism

Epidemiology

Imbalance in oxygen supply and demand

Conversion from aerobic to anaerobic metabolism

Appropriate and inappropriate metabolic and physiologic responses

Resultant systemic physiology:-◦ Cell death and end organ dysfunction◦ MSOF and death

Pathophysiology

Characterized by three stages◦Preshock (warm shock, compensated shock)

◦Shock

◦End organ dysfunction

Physiology

Compensated shock

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

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

Physiology

Shock◦ Initial signs of end organ dysfunction:

◦ Tachycardia

◦ Tachypnea

◦ Metabolic acidosis

◦ Oliguria

◦ Cool and clammy skin

Pathophysiology

End Organ Dysfunction◦ Progressive irreversible dysfunction

◦ Oliguria or anuria

◦ Progressive acidosis and decreased CO

◦ Agitation, obtundation, and coma

◦ Patient death

Physiology

Schemes are designed to simplify complex physiology

Major classes of shock◦ Hypovolemic

◦ Cardiogenic

◦ Distributive

Classification

Results from decreased preload

Etiologic classes◦ Hemorrhage - e.g. trauma, GI bleed, ruptured

aneurysm

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

Hypovolemic Shock

Hypovolemic Shock Hemorrhagic Shock

Parameter I II III IV

Blood loss (ml) <750 750–1500 1500–2000 >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 (bpm) 14–20 20–30 30–40 >35

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

CNS symptoms Normal Anxious Confused Lethargic

Crit Care. 2004; 8(5): 373–381.

Results from pump failure◦ Decreased systolic function◦ Resultant decreased cardiac output

Etiologic categories◦ Myopathic◦ Arrhythmic◦ Mechanical◦ Extracardiac (obstructive)

Cardiogenic 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)

Distributive Shock

Other causes◦ Systemic inflammation – pancreatitis, burns

◦ Toxic shock syndrome

◦ Anaphylaxis and anaphylactoid reactions

◦ Toxin reactions – drugs, transfusions

◦ Addisonian crisis

◦ Myxedema coma

Distributive Shock

Distributive Shock

Septic ShockSIRS 2 or more of the following:

Temp >38 or <36 HR > 90 RR > 20 WBC > 20K >10% bands

Sepsis SIRS in the presence of suspected or documented infection

Severe Sepsis Sepsis with hypotension, hypoperfusion, or organ dysfunction

Septic Shock Sepsis with hyotension unresponsive to volume resuscitation, and evidence of hypoperfusion or organ dysfunction

MODS Dysfunction of more than one organ

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

Clinical Presentation

Done in parallel with treatment! Hx&P/E – helpful to distinguish type of shock Full laboratory evaluation (including H&H,

cardiac enzymes, ABG) Basic studies – CxR, EKG, U/A Basic monitoring – V/S, UOP, CVP, A-line Imaging if appropriate – FAST, CT Echo vs. P/A catheterization

◦ CO, PAS/PAD/PAW, SVR, SvO2

Evaluation

Manage the emergency

Determine the underlying cause

Definitive management or support

Treatment

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?

Manage the Emergency

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

Manage the Emergency

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

Determine the Cause

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