Circulatory SHOCK MAP = CO * TPR
CO = SV * HR
SV = EDV - ESV
Circulatory SHOCK MAP = CO * TPR
CO = SV * HR
SV = EDV - ESV
Definition
Inadequate perfusion (oxygen supply) of tissues, resulting in:
Organ dysfunction
Cellular and organ damage
And if not quickly corrected…
Death
Causes of Shock – a quick list:
Heart Attack
Anaphylaxis
Loss of Circulating Blood Volume (bleeding , burns, dehydration)
Venous Dilation (allergy, pain, drugs, heat stroke, infection)
High or Low Body Temperature
Signs of Shock
Pulse: Rapid, weak, thready
Tachycardia
Why?
Compensation for decreased MAP sensed by ___________
Baroreceptors
Signs of Shock
Respirations
Shallow, irregular, labored
May be tachypnea (increased respiratory rate.) Why?
Compensation for hypoxia sensed by:
Chemoreceptors
Signs of Shock: MAP
Blood Pressure
Low, Falling
Hypotension is a late finding: why?
Compensatory mechanisms work at first to maintain MAP
Signs of Shock
Due to hypoperfusion:
Decreased “mentation” - confused, sluggish, anxious
Skin cold, mottled
Emergency Treatment
Evaluate vital signs
BP, Respiration Rate, Pulse Oximeter, Temp.
Control bleeding
Prevent loss of body heat
CO reduced due to loss of intravascular VOLUME
Reduced venous return
Causes
Most often, blood loss (hemorrhage)
Dehydration
Burns
Fluid lost into peritoneal cavity w/ pancreatitis
MAP = CO * TPR
Low output circulatory failure, affects CO (by decreasing EDV due to decreased venous return.)
Hypovolemic Shock
CO reduced due to loss of intravascular VOLUME
Reduced venous return
Causes
Most often, blood loss (hemorrhage)
Dehydration
Burns
Fluid lost into peritoneal cavity w/ pancreatitis
MAP = CO * TPR
Low output circulatory failure, affects CO (by decreasing EDV due to decreased venous return.)
Cardiogenic Shock
Myocardial Infarction (most frequent cause)
Acute Valvular Dysfunction – e.g. papillary muscle rupture post-MI
Arrhythmia – e.g., heart block, ventricular tachycardia
MAP = CO * TPR
CO severely reduced due to heart dysfunction (“pump failure”)
Cardiogenic Shock
Myocardial Infarction (most frequent cause)
Acute Valvular Dysfunction – e.g. papillary muscle rupture post-MI
Arrhythmia – e.g., heart block, ventricular tachycardia
MAP = CO * TPR
CO severely reduced due to heart dysfunction (“pump failure”)
Obstructive Shock
CO reduced by vascular obstruction:
Obstruction of Venous return (vena cava syndrome – usually neoplasms)
Compression of the heart (pericardial tamponade*)
Outflow from heart (Massive pulmonary embolism, aortic dissection)
Pericardial Tamponade
Life threatening condition caused by fluid (blood, effusion fluid) under pressure around the heart.
Decreases CO by decreasing filling
Causes include pericarditis and MI
Distributive Shock
Maldistribution of flow
Two Categories:
Low Output - Venous pooling due to loss of venous tone
High Output Circulatory Failure
Venous Pooling
A Low Output Circulatory Failure
Often due to spinal shock or drug overdose
Behaves like hypovolemic shock
CO severely reduced because blood is pooled in peripheral veins, rather than returned to heart
Distributive Shock: High Output
CO is normal or elevated; distribution inappropriate
Shock is due to loss of vascular resistance
Examples:
Sepsis, Toxic Shock:
Bacterial endotoxin triggers vasodilation
Anaphylaxis
MAP = CO * TPR
Distributive Shock: High Output
CO is normal or elevated; distribution inappropriate
Shock is due to loss of vascular resistance
Examples:
Sepsis, Toxic Shock:
Bacterial endotoxin triggers vasodilation
Anaphylaxis
MAP = CO * TPR
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