Step I Kaplan Qbank question

[IkeBoy18]

A 57-year-old man is brought to the emergency department because of severe abdominal pain. The patient says that the abdominal pain began shortly after taking a new medication. He has a hx of multiple small bowel masses. Which of the following drugs is the most likely cause of the patients symptoms. (There is a video here with "tin drum" sounds of constipation.

A. Antacids
B. Famotidine
C. Lansoprazole
D. Metoclopramide
E. Sucralfate

I chose A because Aluminum hydroxide can cause constipation.

They said:

The correct answer is D. This patient clearly has bowel obstruction, as evidenced by the high pitched "tinkling" bowel sounds and abdominal distention Medications should be carefully considered for individuals with any degree of bowel obstruction, because of the risk or worsening the obstruction or causing perforation of the intestinal tract. As a general rule, the administration of any product that stimulates the intestinal tract is contraindicated in patients with bowel obstruction. These products can actually promote an intestinal tract perforation secondary to the build-up of pressure behind the obstruction. Since metoclopramide is a prokinetic agent that stimulates the intestinal tract, the use of this agent is absolutely contraindicated in patients with bowel obstruction

They go on to say that antacids are OK in these patients.



OK wait what? I know its late but do they have some combo of right/wrong question with a right/wrong answer? Maybe I didnt get the question somewhere but I was under the impression the question asked what was "causing" his symptoms (constipation)?

 

[IkeBoy18]

Another question sorry I dont feel like typing the whole thing.

Basically the question says a study is done on animals where the pituitary stalk is resected. 2 weeks later hormonal serum concentrations were measured. Which hormone would be increased?

A. Cortisol
B. FSH
C. GH
D. Oxytocin
E. Prolactin
F. Thyroid Hormone

I chose D oxytocin. I figured with the stalk cut that instead of the oxytocin being synthesized in the PVN and SON and stored in the post. pit. it would just be leaked into the blood stream.

They said the answer is E Prolactin because prolactin is inhibited by dopamine which is produced in the hypothalamus. Maybe I dont get what they meant by "resection." To me that means to cut and remove. Meaning there is nothing left of the pituitary after the stalk. So Im not sure how prolactin can even be synthesized?😕

 

[lyth0s]

For the second question they are simply trying to say if the pathway from the hypothalamus to the pituitary is interrupted (resected, not pituitary removal), what hormone would increase? And the answer to that is Prolactin due to it no longer being inhibited by dopamine.

A more simple way to imagine this is the following "If the pituitary stalk is injured during a fall, which hormone would be increased in the serum?"

 

[IkeBoy18]

For the second question they are simply trying to say if the pathway from the hypothalamus to the pituitary is interrupted (resected, not pituitary removal), what hormone would increase? And the answer to that is Prolactin due to it no longer being inhibited by dopamine.

A more simple way to imagine this is the following "If the pituitary stalk is injured during a fall, which hormone would be increased in the serum?"

ok thank you. In that case I can understand the answer.

 

[IkeBoy18]

Another question about alveolar ventilation... Im slightly confused about calculating physiologic dead space. I thought that about 150ml of an avg. 500ml is anatomic dead space so this amount wouldnt be exchanging gas.

when calculating Vd you use Vt to calculate the alveolar dead space but Why are we not using Vt-anatomic dead space in place of just Vt?

Since there is virtually no CO2 in the air roughly all CO2 will be expelled so I understand that
PaCO2-PeCO2/PaCO2 will give us the ratio of how much of the lungs are exchanging gas, I just dont undersand why we multiply this by Vt when 30% of Vt isnt exchanging any gas anyway?

Then when calculating Alveolar ventilation you have to subtract the dead space but not anatomical dead space + physiological (which to me would leave the true alveolar ventilation).

In short I just dont get how physiologic dead space can be calculated with a volume of air (Vt) that of which 150ml doesnt even participate in gas exchange?

 

[Greenbayslacker]

A 57-year-old man is brought to the emergency department because of severe abdominal pain. The patient says that the abdominal pain began shortly after taking a new medication. He has a hx of multiple small bowel masses. Which of the following drugs is the most likely cause of the patients symptoms. (There is a video here with "tin drum" sounds of constipation.

A. Antacids
B. Famotidine
C. Lansoprazole
D. Metoclopramide
E. Sucralfate

I chose A because Aluminum hydroxide can cause constipation.

They said:

The correct answer is D. This patient clearly has bowel obstruction, as evidenced by the high pitched "tinkling" bowel sounds and abdominal distention Medications should be carefully considered for individuals with any degree of bowel obstruction, because of the risk or worsening the obstruction or causing perforation of the intestinal tract. As a general rule, the administration of any product that stimulates the intestinal tract is contraindicated in patients with bowel obstruction. These products can actually promote an intestinal tract perforation secondary to the build-up of pressure behind the obstruction. Since metoclopramide is a prokinetic agent that stimulates the intestinal tract, the use of this agent is absolutely contraindicated in patients with bowel obstruction

They go on to say that antacids are OK in these patients.



OK wait what? I know its late but do they have some combo of right/wrong question with a right/wrong answer? Maybe I didnt get the question somewhere but I was under the impression the question asked what was "causing" his symptoms (constipation)?

check out the bottom of the second page of GI pharm in FA. of course FA is not an exhaustive pharm source, but metoclopramide is the only one listed that's a contraindication to small bowel obstruction.

 

[withrye]

The first question is asking about the symptom of abdominal pain, which in this case is due to intestinal motility against a bowel obstruction. A drug that increases motility will increase the pressure against the obstruction, causing pain. The drug on that list most likely to do that is metoclopramide.

 

[addo]

Another question about alveolar ventilation... Im slightly confused about calculating physiologic dead space. I thought that about 150ml of an avg. 500ml is anatomic dead space so this amount wouldnt be exchanging gas.

can you post the actual questions?

i just wanted to add that on the first question, antacids can mean a bunch of different meds (AlOH, MgOH, NaHCO3 cimetidine, omeprazole and so on...) you cant assume that antacids means aluminium hydroxide.
really simple if you look at it this way
small bowel obstruction =no prokinetic agents (metoclopramide)