Shock (Nassar) Flashcards
what are the 5 types of shock?
- cardiogenic (eg, myocardial infarction or arrhythmia)
- hypovolemic (bleed)
- distributive (eg, sepsis)
- obstructive (eg, cardiac tamponade/Pulm embolism)
- neurogenic (form of distributive shock)
What are the 3 most important therapies for someone in shock?
- volume resuscitation (fluids)
- optimization of oxygen demand (think intubation for someone who’s tachypnic, or in respiratory failure)
- support of the circulation (vasopressors and ionotropes)
2 most common types of shock
septic and cardiogenic
definition of shock
maldistribution of blood flow, causing an imbalance between oxygen delivery and oxygen demand, leading to tissue hypoxia
formula determining O2 delivery
O2 delivery = cardiac output x arterial Oxygen
cardiac function is dependent on which 3 things?
- preload
- contractility
- afterload
**intervention in shock focuses on the first 2.
how do the baroreceptors work to regulate blood pressure?
- via negative feedback.
- high blood pressure activates the baroreceptors, and they in turn inhibit the sympathetic system, lowering BP.
4 causes of distributive shock
- sepsis
- anaphylaxis
- liver cirrhosis
- pancreatitis
T/F Septic shock has elements of hypovolemic shock and cardiogenic shock.
True.
3 contributing factors to septic shock
- systemic vasodilation
- endothelial dysfunction
- capillary leak / relative hypovolemia
what is the significance of pulse pressure in shock.
pulse pressure is a loose measure of stroke volume. If low, think cardiogenic shock. If large or normal, think septic shock /distributive.
pulse, skin appearance and capillary refill in septic shock
pulse = bounding.
skin = flushed (vasodilation)
cap refill = brisk (vasodilation.
pulse, skin appearance and capillary refill in cardiogenic shock
pulse = weak
skin = cyanotic (vasoconstriction)
capillary refill = delayed (vasoconstriction)
Note: these symptoms may also be present in hypovolemic shock. To differentiate, look at JVD
peripheral edema is also commonly present in cardiogenic shock
Case: cold, pale, clammy, mottled skin, delayed cap refill. What does this mean? what is on the DDx?
low cardiac output state,
Could be cardiogenic shock or hypovolemic shock. Look at the JVD to differentiate.
T/F - urine output provides an excellent indicator of organ perfusion.
True.
Which test should be performed ASAP in any patient with shock?
echocardiography
what is the best way to do a non-invasive, real time assessment of circulatory dysfunction in someone with shock?
- ultrasound!
- look at the heart (echo)
- look at IVC, aorta, look for DVTs,
what causes lactate elevation in shock? - 2 things
- low flow states (leading to tissue hypoxia and anaerobic metabolism)
- impaired liver function (impairing clearance of lactate.)
elevated lactate helps diagnose shock
How is mixed (central) venous O2 saturation level used in shock? What is the SVO2 level in low-flow shock and in distributive shock?
the lower it is, the more oxygen tissues are stripping off (the more hypoxic they are).
low flow state (or anemia) - it will be low
distributive/septic shock - it will be normal or high.
4 ways to intervene to improve O2 delivery in shock (in order of priority)
intravascular volume – fluids
vascular resistance - vasopressors
hemoglobin - blood transfusion (if hb
What are some non-invasive ways to determine if patients could benefit from fluids (and that they would not be harmed)
- passive leg raising (increases the blood to the heart by about 500cc - if their stroke output increases then they will be responsive to fluids.)
- inferior vena cava diameter - (ultrasound) - if collapsed, need fluids.
exclusive inotropes
- dobutamine
- isoproterenol
vasoconstrictor of choice for septic shock.
norepinephrine
when should mechanical ventilation be used in pt’s with shock?
- tachypnic patients (excessive O2 utilization by breathing mm
- patient with respiratory failure / low O2 sat.