Usmle Step-2 Subject Series...

[usmletools]

HI all I wanted to start a thread about the most confusing topics for students preparing for Step-2

So you list a topic you are having difficulty with and we will provide content on how to better understand it...

So a good topic would be like

Hey Usmletools I'm having trouble understanding the difference between Diastolic and Systolic CHF

Hey I'm having trouble differentiating between GERD and Accute Gastritis .

So go ahead ask about anything....

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[futuredoctor10]

Topic Requests:
*Basics of ICU including vent settings etc
*hypo/hypernatremia workup and meaning

Broad Topics: any good resources you recommend to review for
a) antibiotics
b) interpreting CXRs and CT imaging
c) EKG interpretation

 

[Ronin786]

Topic Requests:
*Basics of ICU including vent settings etc
*hypo/hypernatremia workup and meaning

Broad Topics: any good resources you recommend to review for
a) antibiotics
b) interpreting CXRs and CT imaging
c) EKG interpretation

For the Ventilation thing, I understood through just memorizing the following:

Ventilation = CO2 = Tidal Volume X Respiratory Rate

If you increase the Tidal Volume or the Respiratory Rate, you're going to increase the amount of CO2 and too much will cause alkalosis. Now if a patient is in alkalosis from the vent you want to decrease the respiratory rate before you decrease the tidal volume. This is because as in normal physiology, decreasing the tidal volume is going to cause a reflex increase in respiratory rate as compensation.

On the other hand, the O2 concentration is basically controlled by two parameters. The Positive End Expiratory Pressure (PEEP) and the Fraction of Inspired O2 (FiO2). An increase in either one of these is going to cause an increase in oxygenation (remember oxygenation is not the same as ventilation).

For O2 just remember that you generally want to keep the FiO2 below 40% in order to limit the effects of oxygen toxicity. That should be a general overview for the questions you'd be asked with regards to ventilation.

As far as Antibiotics go, MTB had a pretty decent list and UWorld has most of what you'll be asked. In general, with practice you'll start to get used to which antibiotic is used for which type of bacteria. I mean I got a question regarding antibiotic use in cholangitis, and even though I'd never studied that specifically, I think I managed to reason it out.

 

[Ronin786]

For the Hyponatremia, you can't go wrong with the explanation found in UWorld.

First step is to calculate the serum osmolarity if possible, with the formula being 2xNa + Glucose/18 + BUN/2.8

Then depending on the osmolarity you look at the volume status of the patient (dehydrated, fluid overload, normal) and you can narrow the differential based on the above table.

Hypernatremia is going to be either anything causing dehydration or Diabetes Inspidus. To differentiate between those two you look at the urine osmolality. If the urine is concentrated then its dehydration and if the urine is dilute (low osmolality) then its diabetes insipidus.

 

[AndyRSC]

b) interpreting CXRs and CT imaging

Felson's Principles of Chest Roentgenology, which covers CXR and CT. It's very concise and consists mostly of pictures, so you can power through it in two days. An invaluable resource if you're ever going to deal with imaging.

c) EKG interpretation

Dale Dubin's Rapid Interpretation of EKGs. If you have an aversion to things written by child pornographers, Thaler's Only EKG Book You'll Ever Need will do the trick. Both are entry-level and give you only what you need.

 

[usmletools]

Please find attached the sample document you requested . Please let me know if u found it easier to understand then the uworld.. explanation....Would love your feedback..

 

[futuredoctor10]

WOW thank you all for the responses!

I appreciate all of you taking the time to help, and hopefully this will help future students with similar questions!