Shock Flashcards
What is shock?
Inadequate tissue perfusion marked by decreased delivery of required metabolic substrates and inadequate removal of cellular waste products
Untreated shock leads to…
Organ dysfunction, organ failure, and death
6 types of shock?
Hypovolemic
Cardiogenic
Septic
Neurogenic
Traumatic
Obstructive
What are the four different categories of shock based on hemodynamic findings?
Hypovolemic (hemorrhagic, GI/UT volume loss, third spacing)
Cardiogenic (myocardial pump failure)
Distributive (sepsis, anaphylaxis, spinal cord injury, corticosteroid insufficiency)
Obstructive (cardiac tamponade, tension pneumothorax, PE)
Hypovolemic shock
HR:
MAP:
CVP:
PAOP:
SVR:
HR: high
MAP: low
CVP: low
PAOP: low
SVR: high
Cardiogenic Shock (Left ventricular failure)
HR:
MAP:
CVP:
PAOP:
SVR:
HR: Increased
MAP: Variable
CVP: normal
PAOP: High
SVR: High
Cardiogenic shock (right ventricular failure)
HR:
MAP:
CVP:
PAOP:
SVR:
HR: High
MAP: variable
CVP: High
PAOP: Normal
SVR: High
Cardiogenic Shock (Biventricular failure)
HR:
MAP:
CVP:
PAOP:
SVR:
HR: High
MAP: Variable
CVP: High
PAOP: High
SVR: High
Distributive Shock (Early vs Late)
HR:
MAP:
CVP:
PAOP:
SVR:
HR: Both High
MAP: Both Low
CVP: low or normal (early); high or normal (late)
PAOP: Low or normal (early); high or normal (late)
SVR: Low for both
Obstructive shock
HR:
MAP:
CVP:
PAOP:
SVR:
HR: high
MAP: low
CVP: high
PAOP: high
SVR: high
Chance of mortality with shock
Hypovolemic:
Cardiogenic:
Septic:
Hypovolemic: Very variable
Cardiogenic: 60%-90%
Septic: 35% - 40%
What are some determinants of shock?
- Loss of circulating intravascular volume
- Inadequate capillary and tissue perfusion
- Disturbed cell metabolism
- Mismatch of oxygen delivery and oxygen demand
What are the four stages of shock?
Initial
Compensatory
Progresive
Refractory
What happens during each stage of shock?
Initial:
Compensatory:
Progressive:
Refractory:
Initial: hypo-perfusion, tissue hypoxia, lactic acidosis
Compensatory: cytokine release, hypervent. endogenous catecholamine release
Progressive: failing compensation, capillary leakage and metabolic acidosis, increased blood viscosity, organ dysfunction (MODS)
Refractory: irreversible organ damage, cell death, degradation of ATP
What is the systemic response to shock?
- Progressive vasoconstriction
- Increased BF to vital organs
- Increase in CO/CI
- Increase in respiratory rate and tidal volume
- Reduced urine production
- Reduction in gastric and intestinal activity
What types of organ dysfunction are associated with shock?
Acute kidney injury
Liver congestion
Gastrointestinal ischemia
ARDS
What is cardiogenic shock?
Critical reduction in myocardial pump capacity (loss of > 40%) leading to malperfusion of tissues
What differential factors should be excluded in cardiogenic shock?
Hypovolemia
Arterial hypoxia
Vasovagal reaction
What percentage of patients with acute MI develop a cardiogenic shock?
5-10%
What are some of the clinical signs of cardiogenic shock?
- Signs of centralized circulation and organ dysfunction
- Agitation
- Pale, cool, clammy skin
- RV dysfunction
- LV dysfunction (leads to pulmonary edema)
Hemodynamic effects of Cardiogenic shock?
Systolic BP < 90mmHG or blood pressure drop by 30mmHG for > 30 min
May need inotropic therapy or balloon pump to stabilize BP
Increased LVEP
Reduced cardiac index
Myocardial etioligies of Cardiogenic shock
Acute MI
Myocarditis
Cardiomyopathy
RV pump failure
Myocardial depressoin
Mechanical etiologies of cardiogenic shock
Acute mitral insufficiency
Aortic insufficiency
Rupture of ventricular septum
Rupture of free ventricular wall
Obstruction
Ischemic Cardiogenic shock progression
Decreased perfusion → Cardiac injury → Decreased stroke volume → Increased catecholamines → increased Heart rate → decreased perfusion… etc
In Cardiogenic shock, the duration of diastole ______ due to _______ ________
decreases; compensatory tachycardia
In cardiogenic shock, what causes metabolic derangement?
Lactic acidosis due to systemic tissue malperfusion → cardiac dysfunction
What are some compensatory mechanisms for cardiogenic shock? What is the trigger?
Trigger: critical decrease in SV
Activation of sympathetic nervous system
Result in increased HR, increase SVR, increased catecholamine release (RAA system), aldosterone, and baroreceptor mediated ADH release
Overall results of compensatory mechanisms in cardiogenic shock
Increased preload and afterload - leads to worsening of myocardial function
Diagnostic tests for cardiogenic shock
EKG
Chest x-ray
arterial blood gas (VBG)
CBC, cardiac enzymes
Serial lactate levels
What are cardiac biomarkers with STEMI?
Cardiac troponin (higher with reperfusion)
CKMB (higher with no reperfusion)
What are the goals for management of cardiogenic shock?
Optimize ventricular filling
Improve coronary perfusion pressure with: vasopressors, inotropics, IABP
If acute MI is the cause: coronary angiography and immediate revascularization
Vasoactive drugs
Inconstrictors (inotropic action + peripheral alpha 1 adrenergic induced vasoconstriction):
Inodilators (inotropic action + peripheral beta 2 adrenergic induced vasodilation):
- Inoconstrictors
- Norepinephrine
- Epinephrine
- Dopamine
- Inodilators
- Dobutamine
- Dopexamine
- Isoproterenol
- Milrinone
What is SIRS and what type of shock is it associated with?
Systemic inflammatory response syndrome - septic shock
What is MODS
multi-organ dysfunction syndrome - also associated with septic shock
SIRS diagnosis has what criteria? How many does it have to meet for diagnosis?
Tachypnea (>20 breath per minute or PACO2 < 32mmHg)
WBC < 4000cells or > 12000 cells
Heart rate > 90bpm
Temperature: fever> 100.4º or hypothermia < 96.8º
Must meet at least 2 of the criteria
What manifestations of inadequate organ perfusion are found in Sepsis?
Alteration in mental state
Hypoxemia
Elevated plasma lactate level
Olliguria (low urine output)
What are the characteristics of septic shock?
Persistent arterial hypotension Despite adequate fluid resuscitation in severe sepsis
Tissue hypoperfusion
Culture positive bacteremia in 30-50% of cases
What are Primary and Secondary MODS?
- Primary
- Direct result of insult, organ dysfunction occurs early in the course
- Secondary
- Consequence of a host response
- Inflammatory host response to toxins and other components of microorganisms
What are some causes of septic and vasodilatory shock?
- Systemic response to infection
- Pancreatitis
- Burns
- Anaphylaxis
- Hemorrhagic shock
- Acute adrenal insufficiency
What are the recommendations for sepsis?
Initial resuscitation
Screening of at risk patients
Antimicrobial therapy
Source control
Infection prevention
Septic shock treatment (within 3 hours)
- Measure lactate level
- Obtain blood cultures prior to administration of antibiotics
- Administer broad spectrum antibiotics
- Administer crystalloid for hypotension or lactate
Septic shock treatment (to be complete within 6 hours)
- Apply vasopressors (for hypotension)
- In the event of persistent hypotension despite resuscitation
- measure CVP
- Measure central venous oxygen saturation
- Remeasure lactate if initial lactate was elevated
How is initial resuscitation performed in septic shock patients?
Crystalloids
Hydroxyethyl starches (increased incidence of renal failure)
Albumin suggested in severe sepsis and septic shock when patients require substantial amounts of crystalloids
What is the first choice vasopressor for septic shock? whats is the second choice? Which is only in very select patients?
Norepinephrine = first choice
Epinephrine = second choice
Dopamine only in very select patients
When would you use inotropic support in septic shock?
In case of myocardial dysfunction (dobutamine)
What is hypovolemic shock?
Traumatic or hemmorhagic shock caused by burns or dehydration
Describe the progression of traumatic shock
Soft tissue or bony injury lead to activation of inflammatory cells and release of inflammatory mediators → Combined inflammatory response and effects of hemorrhage create a more complex and amplified deviation from hemostasis
Hemorrhagic shock occurs with a loss of _____ supply and delivery
oxygen
Oxygen delivery is calculated from ___ x ______ x 10
CO x arterial oxygen content x 10
How many classes of hemorrhage exist? What is their order from least blood lost to most?
- Class I (< 750 ml - <15%)
- Class II (750 - 1500 ml - 15-30%)
- Class III (1500-2000ml - 30-40%)
- Class IV (>2000ml - >40%)
What therapy is used for hemorrhagic shock?
- Volume therapy
- Cristalloid solutions
- Colloid solutions
- PRBC
- FFP
- SDPs
- Small volume resuscitation
What is obstructive shock?
Form of cardiogenic shock that results from mechanical impediment to circulation
Depressed cardiac output rather than primary cardiac failure
What are etiologies associated with obstructive shock?
Pulmonary embolism or tension pneumothorax
What is Neurogenic shock?
Profound vasodilation of arterial and venous blood vessels caused by injury of the brain stem, the spinal cord or traumatic brain injury
What is anaphylactic shock?
Distributive disturbance of the blood volume
or
physical, chemical or osmotic induced
- hypersensitivity reaction
What is IgE-dependent anaphylactic shock
What is IgE independent anaphylactic shock
IgE dependent = type-I-allergic anaphylactic
IgE independent = anaphylactoid
Anaphylactic shock classification
Class 0 - locally limited cutaneous reaction
Class 1 - disseminated cutaneous reaction
Class 2 - Hemodynamic dyregulation
Class 3 - Shock, bronchospasm
Class 4 - Respiratory and circulatory arrest
Therapy for anaphylactic shock?
Rapid infusion of cristalloid (or colloid) solutions
Epinephrine (for bronchodilation, positive inotrope, anti inflamm)
Norepinephrine (refractory hypotension)
Vasopressin
Hemodynamic Responses to different types of shock?
