Shock today
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Transcript of Shock today
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
Pathophysiology
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
Physiology
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
Pathophysiology
Shock Initial signs of end organ dysfunction
Tachycardia Tachypnea Metabolic acidosis Oliguria Cool and clammy skin
Physiology
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
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.
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)
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
Septic Shock
SIRS 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
Clinical presentation varies with type and cause, but there are features in common
Hypotension (SBP<90 ) 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
Manage the Emergency
Your patient is in extreme – 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
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
Determine the Cause
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
Controversies
IVF Resuscitation Limited resuscitation in penetrating trauma Use of hypertonic saline resuscitation in trauma Endpoints for prolonged resuscitation
Pressors Best pressors for distributive shock
Monitoring Most appropriate timing and use for PA
catheterization or intermittent echocardiogram