from NBME exam Flashcards
What virus usually causes croup?
parainfluenza virus
right dominant circulation vs. left dominant circulation
right dominant circulation is more common. in a right dominant heart, the posterior descending/interventricular artery, which supplies the posterior 1/3 of the IV septum and the posterior wall of the ventricles, is supplied by the RCA.
In a left dominant heart, the PDA arrises from the LCX.
There are also some people who have codominant circulation.
types of shock
distributive shock: this is HIGH OUTPUT failure. Patients have decreased TPR, increased CO, and increased venous return. pulmonary capillary wedge pressure is decreased. they have warm, dry skin and blood pressure does not improve with IV fluids.
hypovolemic: TPR incr, CO decr.
cardiogenic shock: decr. CO, incr. TPR.
PCWP is incr. in cardiogenic shock, PCWP is decr. in hypovolemic shock.
hypovolemic and cardiogenic will feel cold and clammy.
neurogenic shock: decr. TPR, decr. CO.
explain acetaminophen overdose and treatment
overdose produces hepatic necrosis becasue the acetaminophen metabolite NAPQI depletes glutathione and causes free radical damage and toxic tissue adducts. N-acetylcysteine is the antidote because it regenerates glutathione.
cholinesterase poisoning
often due to organophosphates that irreversibely inhibit AChE. causes excessive parasympathetic stim. After stabilizing airway, FIRST GIVE ATROPINE. Then, you might give pralidoxime (regenerates AChE if given early).
creatinine phosphate
phosphorylated creatinine molecule that serves as a rapidly mobilizable reserve of high energy phosphates in skeletal muscle and brain. It is synthesized in the liver and transported to muscle for storage.
alveolar gas equation
PAO2 = pressure of inspired O2 - (PaCO2/R).
usually A-a gradient is about 150 - (PaCO2/0.8)
A-a gradient
normal A-a gradient is about 10-15 mmHg. increases in A-a gradient occur in hypoxemia- causes include shunting, V/Q mismatch, fibrosis (NOT resp. depression!!).
