Shock Flashcards
Shock is a broad term that describes _____________________.
a physiologic state where oxygen delivery to the tissues is inadequate to meet metabolic requirements. It may also be thought of as an imbalance between tissue oxygen supply and demand.
Differentiate compensated and uncompensated shock.
Both compensated and uncompensated shock present with inadequate perfusion, but compensated shock is characterized by normal blood pressure. Uncompensated shock is characterized by low blood pressure.
Describe the four types of shock.
- Hypovolemic (most common): decreased fluid volume –from hemorrhage or dehydration –leads to decreased perfusion
- Cardiogenic: decreased cardiac output leads to decreased perfusion
- Distributive: pathologic peripheral vasodilation leads to decreased perfusion; can be caused by infection, anaphylaxis, or neurogenic causes
- Obstructive: non-cardiac obstruction to blood flow leads to decreased perfusion (such as pulmonary embolism, tension pneumothorax, tamponade, or constrictive cardiomyopathy
Paradoxically, early shock may present with elevated _________________.
blood pressure
What signs suggest shock?
- Cool extremities
- Dry mucous membranes
- Pale extremities
- Decreased capillary refill
- Cyanosis
- Thready pulses (rapid, scarcely palpable pulses)
- Tachycardia
- Hypotension
Other signs will be specific to the type of shock; for instance, tamponade will show JVD and sepsis will show fever.
What is the shock index?
HR/SBP
Normally it is 0.5 - 0.7. If it is greater than 1.0, this predicts worse outcome in shock.
Which types of shock present with increased HR?
All four types
Which types of shock present with increased CVP?
Cardiogenic and obstructive, because in both cases blood is not being moved by the heart
Which type of shock classically has decreased SVR?
Septic shock
Note: obstructive shock due to tension pneumothorax can have decreased SVR.
Describe what labs can show end-organ damage.
Lactate is an indicator of anaerobic metabolism in all tissues.
- Brain: ischemic changes on CT; AMS
- Heart: troponin; CK-MB; arrhythmia
- Lungs: ARDS or edema on x-ray
- Liver: elevated AST/ALT
- Kidneys: elevated creatinine and BUN
Intubation is desirable in those with shock because it can reduce the metabolic load of breathing, but there are some disadvantages to it: ____________________.
(1) drugs used in intubation can cause negative hemodynamic effects; (2) PPV can further reduce SVR
Patients with shock are given fluids. Which conditions should you be cautious of in administering fluids?
Pulmonary edema
Shock is considered to be normalized when what things occur?
- Normalization of hemodynamic parameters (BP, HR, urine output)
- Lactate decreases
- Resolution of acidosis
Vasopressors that also cause _____________ can be used to treat hypovolemic shock.
reuptake of fluid in the kidneys
Example: ddAVP
Distributive shock is kind of like hypovolemic shock. How?
In distributive shock, the vessels dilate too much. As such, the fluid is relatively low (it can’t fill the additional volume).
Sepsis is the most common cause of distributive shock, but ______________ can also cause it.
spinal cord injuries
Why is epinephrine used to treat anaphylaxis?
A couple reasons: (1) it is a potent vasoconstrictor, (2) it leads to smooth muscle relaxation in the airway, and (3) it stabilizes mast cells
Other than epinephrine, what treatments are given to those with anaphylaxis?
- Antihistamines, both H1 and H2 antagonists
* Steroids
List some of the causes of cardiogenic shock.
- MI
- Arrhythmia
- Valvular stenosis
- Ventricular rupture
- Congestive heart failure
- Myocarditis (common in children)
List some of the causes of obstructive shock.
- Pulmonary embolism
- Tension pneumothorax
- Tamponade
What dose epinephrine is given in codes?
1 mg
What is renal dosing of dopamine?
Lower doses of dopamine only affect the afferent arteriole, while higher doses target the alpha and beta adrenergic receptors too.
Norepinephrine is first-line for ____________ shock.
distributive
What does dopamine target at low and high doses?
Low: beta-1 and beta-2
High: alpha-1, beta-1, and beta-2
What are some indications for central lines?
- Vasopressors for longer than an hour; vasopressors can only be given peripherally for about an hour before becoming too constricted
- Dialysis
- Multiple medications that cannot be mixed
Central lines are inserted into the __________ jugular.
internal
External jugular lines are not considered central lines.
Mean arterial pressure (MAP) is equal to ____________.
CO x SVR
Neurogenic shock specifically results from _________________.
injury to the sympathetic chain ganglion that disrupts sympathetic tone to the vasculature
In addition to being found in the arteries, alpha-1 receptors are also found in the heart. What do the cardiac alpha-1 receptors do?
They increase conduction and excitation.
Beta-1 stimulation causes increased _________________.
cardiac conduction and contractility
