Shock Flashcards
What are the two peices of data used to diagnose shock?
Hemodynamics andmixed venous O2
A reflection of LAP, which, in the absence of mitral valve disease, is an indication of
LVEDP and LVEDV
Left ventricular failure, aortic valve disease, mitral valve disease, and cardiogenic shock are conditions w/ increased
PCWP AND LAP
When LAP is greater than 20 mmHG, we will likely see
Pulmonary Edema
What is an example of a condition with increased PCWP but LOW left atrial pressure?
Pulmonary Artery Hypertension
CO x the amount of oxygen in the arterial blood gives us the
Oxygen delivery to tissues
CO x amount of oxygen in the venous blood gives us
Oxygen returne to the heart
Mixed venous oxygen content is derived from the
Fick equation
What is the Fick equation?
(CaO2 - CVO2)/CaO2
If oxygen delivery declines than we see an increase in
Extraction ratio
What are three factors that affect oxygen delivery?
CO, Hb, and PaO2
Reflects the balance between oxygen delivery and oxygen demand
SvO2
A physiological state characterized by insufficient oxygen delivery to the tissues
Shock
We see no protein or RNA synthesis w/ low levels of
ATP
Low ATP levels also causes failure of membrane ion pumps which leads to loss of
mb potential
The cytosolic proton burden increases when we have low ATP levels. This causes
Acidosis
Clinical shock is often accompanied by
Hypotension
MAP less than 60 mm Hg in a previously normotensive person
Clinical Shock
What are the two compensatory responses ot hypotension
Broreceptor response and renin-angiotensin system
The baroreceptor respopnse autoregulates
Blood Pressure
Decrease in arterial pressure leads to decreased baroreceptor firing in the
Carotid sinus and aortic arch
Hypotension disinhibits the
Vasomotor center
Decreased baroreceptor firing causes a decrease in inhibitory neurons which leads to increased sympathetic tone and increased
HR and contratility
In response to low BP, the kidney releases
Renin
Renin then causes activation of
AN-II
AN-II then leads to which 3 things?
- ) Vasoconstriction
- ) Na+ resorption
- ) Net water resorption
Metabolic rates of heart and brain are high with low nutrient stores. Therefore they are critically dependent on blood flow for
Oxygen delivery
What are the visual features of low CO shock?
Cool, clammy skin, pale or gray color
The cool, clammy skin and pale or gray color seen in low CO shock are the result of vasoconstriction which shunts blood from
Periphery to vital organs
We can also see agitation/anxiety; “sense of impending doom” confusion; obtundation w/
Low CO shock
Normal capillary refill time is less than
2 seconds
What are some abnormal findings as far as vascularity to the hands?
Clubbing, splinter hemorrhage, and peripheral cyanosis
A metabolic acidosis is a clasic feature of
Shock
The metabolic acidosis in shock induces
Tachypnea
This tachypnea results in a compensatory
Respiratory alkalosis
Cardiogenic shock and myocardial infarction both decrease
Myocardial contractility
A pulmonary embolism increases
Afterload
Hypovolemic shock and obstructive shock are both causes of decreased
Preload
Caused by a tension pneumothorax and pericardial tamponade
Obstructive shock
Leading cause of death for patients with acute MI
Cardiogenic Shock
Occurs in 5-7% of patients w/ acute MI
Cardiogenic shock
More prominent in STEMI than NSTEMI and mortality approaches 80%
Cardiogenic shock
Cardiogenic shock is the result of primary
Pump failure
i.e. MI in ventricle 40%
Pathophysiology is: coronary occlusion/MI, profound depression of contractility, reduced CO, and low BP
Cardiogenic shock
What are three clinical findings of cardiogenic shock?
Hypotension, hypoperfusion, and pulmonary congestion
Tachycardia, faint pulses, soft heart sounds, and displaced apical impulse are the result of hypotension and low CO seen in
Cardiogenic shock
Component of cardiogenic shock that causes agitation, disorientation, or lethargy w/ cool, clammy, or cyanotic extremities
Hypoperfusion
Component of cardiogenic shock leading to pulmonary rales and elevated JVP
Pulmonary congestion
Pulmonary congestion results in which murmur
S3
Caused by intravascular volume depletion
Hypovolemic Shock
Loss of blood cell mass and loss of plasma volume lead to
Hypovolemic shock
The essential derangement of hypovolemic shock is
Decreased preload
Class 2 hypovolemic shock can be recognized by
Narrow pulse pressure
Characterized by cold, clammy skin, tachycardia, and a narrow pulse pressure
Hypovolemic shock
The result of impaired venous return to the R or L ventricle
-caused by pericardial tamponade and tension pneumothorax
Obstructive shock
Clinically presents w/ absent breath sounds, JVD, and tracheal deviation
Tension pneumothorax
What are the three types of distributive shock?
Septic shock, neurogenic shock, and anaphylactic shock
Decrease in peripheral vascular resistance despite increased vasopressors
Septic Shock
Loss of sympathetic tonesecondary to spinal cord injury
Neurogenic shock
Histamine, leukotriene C4, prostaglandin D2 release cause profound vasodilatation
Anaphylctic shock
Third leading cause of death in US (from all causes)
-35-40% mortality
Septic Shock
25-30% of cases of sepsis are caused by
Gram negative sepsis
30-50% of cases of sepsis are caused by
Gram positive and mized sepsis
Initiated by danger signals such as Pathogen-associated molecular patterns (LPS, flagellin, fimbria, DNA etc.)
Septic Shock
We see distributive shock, diffuse endothelial injury, and altered microvascular flow w/
Sepsis
Failure of vascular smooth muscle constriction
Distributive (vasoplegic) shock
Inflammatory mediators can disrupt cell-cell contacts leading to
Edema
We see a marked decrease in peripheral vascular resistance w/
Septic Shock
CO and peripheral blood flow are increased w/
Setic shock
Septic shock is characterized by diminished vasoconstrictor response to
Catecholamines
