Shock Flashcards
shock is circulatory failure causing inadequate ______ delivery to cells.
oxygen
What is the quick and dirty beside evaluation for shock? (think: CHAOS)
- Cardiogenic
- Hypovolemic
- Adrenal (distributive)
- Obstructive
- Septic (distributive)
Which of the following subdivisions of shock DOES NOT lead to reduced cardiac output?
a. hypovolemic
b. obstructive
c. cardiogenic
d. distributive
d. distributive
* distributive leads to low peripheral resistance*
What defines preload?
a. Load imposed on resting muscle that stretches the muscle to a new length
b. Velocity of muscle contraction when muscle load is fixed
c. Load which muscle must act against during contraction
a. Load imposed on resting muscle that stretches the muscle to a new length
What defines afterload?
a. Load imposed on resting muscle that stretches the muscle to a new length
b. Velocity of muscle contraction when muscle load is fixed
c. Load which muscle must act against during contraction
c. Load which muscle must act against during contraction
What defines contractility?
a. Load imposed on resting muscle that stretches the muscle to a new length
b. Velocity of muscle contraction when muscle load is fixed
c. Load which muscle must act against during contraction
b. Velocity of muscle contraction when muscle load is fixed
What are the 3 stroke volume determinants?
- preload
- contractility
- afterload
Contractility is the ______ ability for your heart to squeeze.
intrinsic
regardless of what the preload is
Delivery of oxygen (DO2) is related to what 2 factors?
CaO2 (arterial oxygen content) x Q (perfusion)
Normal arterial oxygen content (CaO2) is equal to _______ mL O2/dL.
20 mL O2/dL
Oxygen consumption (VO2) is equal to what?
VO2 = SaO2 (arterial) - SvO2 (venous)
What 3 factors determine your arterial oxygen content?
- hemoglobin
- SaO2 (arterial oxygen saturation)
- PaO2 (arterial oxygen tension)
What are 3 common etiologies of hypovolemic shock?
- hemorrhage
- third spacing (e.g. burns, pancreatitis)
- dehydration
What are 3 common causes of obstructive shock?
- cardiac tamponade
- PE
- tension pneumothorax
What are the 4 common causes of distributive shock?
- septic shock
- adrenal insufficiency
- neurogenic shock
- anaphylaxis
What is the mechanism of hypovolemic shock?
a. reduced ability of the heart to pump blood forward
b. reduced venous return leading to reduced preload and reduced C.O.
c. mechanical obstruction to normal venous return C.O.
d. dilatation of vasculature
b. reduced venous return leading to reduced preload and reduced C.O.
What is the mechanism of distributive shock?
a. reduced ability of the heart to pump blood forward
b. reduced venous return leading to reduced preload and reduced C.O.
c. mechanical obstruction to normal venous return C.O.
d. dilatation of vasculature
d. dilatation of vasculature
What is the mechanism of cardiogenic shock?
a. reduced ability of the heart to pump blood forward
b. reduced venous return leading to reduced preload and reduced C.O.
c. mechanical obstruction to normal venous return C.O.
d. dilatation of vasculature
a. reduced ability of the heart to pump blood forward
What is the mechanism of obstructive shock?
a. reduced ability of the heart to pump blood forward
b. reduced venous return leading to reduced preload and reduced C.O.
c. mechanical obstruction to normal venous return C.O.
d. dilatation of vasculature
c. mechanical obstruction to normal venous return C.O.
What is the first sign of critical illness?
tachypnea
What is the first sign of shock?
oliguria (low urine output)
What 2 labs do you want to get for shock?
- lactate
- SVO2/ScVO2 (venous oxygenation)
If O2 delivery is impaired tissues compensate by ___________.
increasing extraction
If O2 delivery is impaired tissues compensate by increasing extraction. This results in what?
reduced venous saturation returning to the right heart
A “mixed” venous saturation (SVO2) is sampled from where?
distal to RV = pulmonary artery
A central venous saturation (ScVO2) is sampled from where?
cavoatrial junction
What is the relationship between SVO2 and ScVO2?
- ScVO2 is 5-10% lower than SVO2
* however, serial values track same as SVO2*
- What is “normal” SVO2?
- What does a low SVO2 <60% indicate?
What does a high SVO2 >80% indicate?
- normal: 60-80%
- low: O2 supply insufficient for demand
- high: adequate supply, but tissue unable to extract O2 (e.g. cyanide toxicity causing mitochondrial dysfunction)
- lactate will be elevated in low or high SVO2
What device do you need to measure a SVO2?
pulmonary catheter
What device do you need to measure a ScVO2?
centra line
What may be the only clinical signs of preshock?
- increase in HR
- small decrease in BP
What causes a metabolic acidosis in shock?
elevated lactate
What changes in preload, CO, and SVR do you see in hypovolemic shock?
- decrease preload
- decrease CO
- increase SVR
What changes in preload, CO, and SVR do you see in cardiogenic shock?
- increase preload
- decrease CO
- increase SVR
What changes in preload, CO, and SVR do you see in obstructive shock?
- increase or decrease preload
- big decrease in CO
- increase SVR
What changes in preload, CO, and SVR do you see in distributive shock?
- decrease in preload
- increase/decrease in CO
- DECREASE SVR
only subtype of shock that decreases SVR = distributive
What are the 3 stages of shock?
- “warm shock” = pre-shock
- shock
- end-organ dysfunction
What is the main treatment for shock?
treat underlying cause
What is the first line treatment for volume resuscitation?
- isotonic crystalloids (normal saline, LR)
What type of gauge needle do you want to use for a peripheral IV in a patient with shock?
short + fat
What is a safe way to administer vasopressors?
central venous catheter
Stimulating A1 receptors result in what?
vasoconstriction
Stimulating A2 receptors results in what?
vasodilatation
Stimulating B1 receptors results in what 2 things?
increase in inotropy and chronotropy
Stimulating B2 receptors results in what?
smooth muscle relaxation
Stimulating dopaminergic receptors (DA1/DA2) results in what?
varying effects based on dose
What is the main adverse effect of vasopressors?
distal ischemia
Phenylephrine has what receptor activity?
alpha-1 = causes vasoconstriction
Norepinephrine has what receptor activity? (2)
- strong alpha-1 = vasoconstriction
- modest Beta-1 = increase CO
Epinephrine has what receptor activity? (3)
- strong alpha-1 = vasoconstriction
- strong beta-1
- modest beta-2
Dobutamine has what receptor activity?
- strong beta-1 and beta 2 activity
Isoproterenol has what receptor activity?
- strong beta-1 and beta-2 activity
