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Discussion Starter · #1 ·
Hello USMLE Forums Users!

MedicalExams.com is giving away 60 Free Challenging USMLE Step 1, 2 and 3 questions with full explanations to everyone who signs up to our site, no obligation!

We are also offering a coupon exclusive to this forum.

The coupon code is: fallspecial15 - It's good for 15% off of all exams!

If you're still wondering why you should sign up, here's a sample of one of our 4000+ questions with full explanations.

Sample Question+Explanation

You are called to assess a 4600g newborn who was noted be cyanotic. Upon arrival, you note a bluish
discoloration of the patient's extremities, face, and trunk. An initial arterial blood gas analysis indicates a pAO2
of 40 mm Hg. Physical examination reveals a grade 2/6 systolic murmur and a loud second heart sound. The
chest radiograph reveals a normal sized heart and decreased pulmonary vascular markings. After placing the infant
under a hood containing 100% oxygen, his cyanosis improves, and you obtain the following arterial blood gas
sample:

pH = 7.36
pCO2 = 37 mm Hg
pAO2 = 101 mm Hg
HCO3- = 20
Base excess = -3

Which of the following is the most appropriate interpretation of this infant's diagnostic evaluation?

A. The normal pAO2 on 100% oxygen indicates that cyanosis is likely due to methemoglobinemia
B. The arterial blood gas suggests alveolar hypoventilation is the mechanism for cyanosis
C. There is increased pulmonary vascular resistance, leading to a right-to-left shunt at the atrial or ductal levels
D. There is a right-to-left shunt at the ventricular level, likely due to complex congenital heart disease
E. This is acrocyanosis, and is a normal finding in a young newborn

________________________________________________________________

Explanation

The correct answer is choice C.

This infant has persistent pulmonary hypertension of the newborn (PPHN). Remember that in fetal life, oxygenation occurs in the
placenta - the resistance in the pulmonary vascular bed is high, and blood is shunted away from the fetal lungs through the
ductus arteriosus and the foramen ovale. At birth, however, the pulmonary vascular resistance should drop, beginning with the
infant's first breath. This allows blood to enter the lungs to be oxygenated, and the foramen ovale and ductus arteriosus should
close within hours to days of birth.

In some infants, this process does not occur - the vascular resistance in the pulmonary bed remains high. Because blood follows
the path of least resistance, it is thus "easier" for the blood to pass through the ductus arteriosus or foramen ovale and enter the
systemic circulation, without ever passing through the lungs to be oxygenated. This causes hypoxemia and cyanosis.

PPHN can result from a variety of conditions, most notably meconium aspiration syndrome and congenital diaphragmatic hernia.
Infants of diabetic mothers also have an increased rate of PPHN - and this infant's large size suggests that may be the case in this
vignette.

Even if you didn't recognize that this was PPHN, the clues in the stem should have led you to that physiologic explanation. For
example, the chest x-ray shows decreased pulmonary vascular markings, indicating that blood is not ever entering the lungs. Also,
the single, loud S2 is a marker of pulmonary hypertension.

Methemoglobinemia (choice A) can cause cyanosis, but the pAO2 should improve markedly with the administration of 100%
oxygen. Classically, patients with methemoglobinemia will remain cyanotic even on 100% O2, even though their pAO2 is high.

Hypoventilation (choice B) can cause hypoxemia and cyanosis, but would also cause CO2 retention.

Complex congenital heart disease (choice D) could cause cyanosis. However, the improvement that this patient experienced with
100% oxygen suggests that this is not the case. Even with 100% oxygen, infants with cyanotic heart disease will seldom attain a
pO2 of greater than 100 mm Hg, or have a rise of greater than 10-30 mm Hg from their pre-hyperoxygenated baseline. Also, in
this case, there are clues in the chest x-ray and physical exam that suggest an alternate mechanism of hypoxemia.

Acrocyanosis (choice E) is a bluish discoloration of the extremities that is a normal finding in infants. It is not associated with
systemic hypoxemia. This infant's cyanosis is initially severe and pronounced, and associated with a markedly decreased pAO2.

Suggested References
Tingelstad J. Consultation with the specialist: nonrespiratory cyanosis. Pediatr Rev. 1999; 20:350-352.
 

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Discussion Starter · #2 ·
Another Free USMLE Sample Question from MedicalExams.com

The development of conduction disturbances due to myocardial infarction and arrhythmia depends on the vascular
supply of the different components of the heart conduction system.

All statements are correct about the blood supply of the conduction system of the heart EXCEPT:

A. Sinoatrial node is is supplied by the right coronary artery in 60 percent of patients and by the left circumflex
artery in 40 percent of patients
B. Atrioventicular node supplied mostly by the right coronary artery
C. Main or proximal left bundle branch is mostly supplied by the left anterior descending artery
D. Left posterior and anterior fascicles are supplied by the left anterior descending artery
E. Right bundle branch is supplied by the left anterior descending artery

-Post Answer Below:

Full Answer+Explanation will be posted soon.

Try 60 Free questions like this at: http://MedicalExams.com/
 

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these are step 1 questions

These are nice questions. But I don't think they are Step 2 CK questions. These are Step 1 questions :toosad:
 

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Discussion Starter · #5 ·
These are nice questions. But I don't think they are Step 2 CK questions. These are Step 1 questions :toosad:
Sorry for the mix up!

Here is an example of one of our Step 2 CK Questions. The full explanation will be posted soon.

A 62 year old man with advanced cirrhosis is treated with lactulose for hepatic encephalopathy. On physical
examination he is confused and has asterixis. Blood pressure is 100/60 while the patient is supine and his pulse
rate is 110 beats per minute. There is no peripheral edema, but ascites is detected. Serum sodium concentration is
160 mmol/L and potassium is 2.6 mmol/L. The body weight is 64 kg.

This patient's hypernatremia can be best described by which of the following?

A. Excessive insensible losses, primarily of water (euvolemic hypernatremia)
B. Hypotonic losses of sodium and potassium and water (hypovolemic hypernatremia)
C. Hypervolemic hypernatremia
D. Not enough information to determine status
E. None of the above

-Post Answer Below:

Full Answer+Explanation will be posted soon.

Try 60 Free questions like this at: http://MedicalExams.com/
 

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Sorry for the mix up!

Here is an example of one of our Step 2 CK Questions. The full explanation will be posted soon.

A 62 year old man with advanced cirrhosis is treated with lactulose for hepatic encephalopathy. On physical
examination he is confused and has asterixis. Blood pressure is 100/60 while the patient is supine and his pulse
rate is 110 beats per minute. There is no peripheral edema, but ascites is detected. Serum sodium concentration is
160 mmol/L and potassium is 2.6 mmol/L. The body weight is 64 kg.

This patient's hypernatremia can be best described by which of the following?

A. Excessive insensible losses, primarily of water (euvolemic hypernatremia)
B. Hypotonic losses of sodium and potassium and water (hypovolemic hypernatremia)
C. Hypervolemic hypernatremia
D. Not enough information to determine status
E. None of the above

-Post Answer Below:

Full Answer+Explanation will be posted soon.

Try 60 Free questions like this at: http://MedicalExams.com/
Woow this is really a difficult question, I have no clue at all :toosad:
 

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Discussion Starter · #8 ·
10 premium question for the USMLE - Courtesy of Medicalexams.com

10 premium question for the USMLE - Courtesy of Medicalexams.com - 60 free questions with a signup....Premium quality!

Full answers + explanations at: http://MedicalExams.com

1) A 36 year old woman with presents to her primary care doctor for medical clearance. She is planning on a elective hernial repair. She was recently diagnosed with sarcoidosis several months ago and placed on prednisone. Upon inspection, her physician notices a well nourished woman with telangiectasias and purple red marks on her extremeties. She also has some signs of hirsutism that he did not notice on her previous visit several months ago.

Which of the following would correctly describe her primary acid-base disturbance?

A) Low pH, Low HCO3, High Base Deficit, Low pCO2.

B) Low pH, High HCO3, High Base Excess, High pCO2.

C) Neutal pH, Low HCO3, High Base Deficit, Low pCO2.

D) High pH, High HCO3, High Base Excess, High pCO2.

E) High pH, Low HCO3, High Base Excess, Low pCO2.

Explanation will be posted soon....

2) A 23-year-old man with rheumatic mitral regurgitation presents to your clinic with frequent palpitations and exercise intolerance. He is currently in no distress and other wise appears healthy. He is a current smoker and has a 10 pack-year smoking history. He has no history of diabetes and has never been hospitalized since he had rheumatic fever as a child.

Which one of the following is not an indicator of the severity of his mitral regurgitation?

A) Third heart sound

B) The loudness of the murmur.

C) Signs of heart failure.

D) Presence of thrill.

E) S4

Explanation will be posted soon....

3) A 60-year-old man complains of left eye pain and photophobia. On examination there is an erythematous rash of the periorbital skin and forehead on the left side. You also note erythema and a small vesicle on the tip of the patient's nose. His ipsilateral conjunctiva is injected and after staining the affected eye with fluorescein, Wood's lamp examination reveals corneal uptake in a fine branching pattern.

What is the most appropriate therapy for this patient?

A) Oral acyclovir 800mg three times a day for 7-10 days

B) Oral valacyclovir 500 mg three times a day for 7 days

C) Oral famciclovir 500mg three times a day for 7 days

D) Oral prednisolone, 40mg daily for 7 days

E) Topical acyclovir, 5 times a day until resolution of ocular symptoms

Explanation will be posted soon....

4) Match the most likely micro-organism with the clinical scenario:

A 35-year-old woman, recently returned from a hiking trip in Arizona, presents with low-grade fever, cough with minimum clear sputum production, and rash. She is otherwise healthy with no significant past medical history. She has been on treatment with ventolin for intermittent asthma and she does have seasonal allergies.

A) Coccidioides immitis

B) Measles virus (rubeola)

C) Mycobacterium tuberculosis

D) Mycoplasma pneumoniae

E) Histoplasmosis

5) A 15-year-old high school student and several of her friends ate lunch at a local Chinese restaurant. They all were served the daily luncheon special, which consisted of sweet and sour pork with vegetables and fried rice. All the girls developed nausea, vomiting, abdominal pain, and diarrhea within 6 hours of eating lunch. The were all sent to the local emergency department for work-up of their suspected food poisoning. The children are all otherwise healthy and none are on any medication and have no known allergies.

Which of the following is the most likely cause of these symptoms?

A) Bacillus cereus

B) Staphylococcus aureus

C) Clostridium botulinum

D) Clostridium perfringens

E) EHEC (Enterohemorrhagic Escherichia coli)

6) A 57-year-old man is brought to the emergency room with a 2 hour history of central crushing chest pain radiating to the left arm. Clinical examination revealed a sweaty distressed gentleman with a pulse rate of 130, blood pressure of 140/95, but no other signs of cardiac or respiratory disease.

An electrocardiogram showed a wide-complex ventricular tachycardia at a rate of 126 beats per minute. The physician prescribed a drug to decrease Sino atrial (SA) node automaticity, increase Atrio Ventricular (AV) node refractoriness, and decrease AV node conduction velocity.

Which of the following agents was most likely prescribed?

A) Amiodarone

B) Disopyramide

C) Lidocaine

D) Propranolol

E) Verapamil

7) A 65- year- old retired truck driver who smokes a pack of cigarettes daily is diagnosed with essential hypertension. He has no previous history of cardiovascular disease or sexual dysfunction. In the primary care physician's office, his blood pressure is 170/95 mmHg. He is prescribed a single therapeutic agent. Shortly after the beginning of the treatment, he experiences difficulties in obtaining and maintaining an erection.

What medication is most likely to have caused this adverse effect?

A) Hydrochlorothiazide

B) Enalapril

C) Losartan

D) Prazosin

E) Verapamil

8) A 34-year-old California man in otherwise good health presents with coughing spasms followed by post-tussive emesis for three weeks. A nasopharyngeal swab was collected and the culture came back positive for a gram negative aerobic extracellular coccobacillis.

According to the Centers for Disease Control and Prevention, which one of the following is the best next step?

A) Prescribe inhaled albuterol

B) Do not prescribe antibiotics for the patient until culture results are available

C) Administer whole-cell pertussis vaccine

D) Treat close household contacts with antibiotics

E) Strict isolation of patient

9) A 10 year-old male is brought to the urgent care clinic by his grandmother. She tells you that her cat bit the boy on the hand approximately 8 hours ago while he was teasing the animal. He just told his grandmother a few minutes ago because his hand started to hurt. The cat is up to date on all immunizations, as is the patient with his as their immunization records showed.

The child is otherwise healthy except for recurrent otitis media and mild season allergies. He is allergic to penicillins as he developed a rash the last time he took the antibiotic. On examination, vital signs are: BP 106/68 mmHg, Temp 99 F, Resp 17/min, Pulse 92/min. The physical exam is remarkable only for a deep pair of puncture wounds to the right thenar eminence, mild surrounding erethema, and localized tenderness to palpation.

After appropriate wound care in the urgent care clinic, what is the best antibiotic regimen for this patient?

A) cephalexin and trimethoprim-sulfamethoxazole

B) clindamycin and trimethoprim-sulfamethoxazole

C) azithromycin and cephalexin

D) azithromycin and trimethoprim-sulfamethoxazole

E) ciprofloxacin and clindamycin

10) You are working in a local TB health center and you are about to interpret the result of a Mantoux tuberculin skin test on one of your patients who has had a history of fever and cough.

Which of the following is NOT true about tuberculin skin testing (TST) for tuberculosis?

A) Patients who have received BCG vaccine should not have TST.

B) An initially negative test does not exclude the possibility of active infection.

C) A subsequent (2nd) negative test, several weeks after the first, does not exclude the possibility of active infection.

D) A previously TST-positive patient can become TST-negative later in life.

E) For TST to reflect recent infection it should be done > 3 weeks after exposure
 

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Respiratroy Acidosis?

10 premium question for the USMLE - Courtesy of Medicalexams.com - 60 free questions with a signup....Premium quality!

Full answers + explanations at: http://MedicalExams.com

1) A 36 year old woman with presents to her primary care doctor for medical clearance. She is planning on a elective hernial repair. She was recently diagnosed with sarcoidosis several months ago and placed on prednisone. Upon inspection, her physician notices a well nourished woman with telangiectasias and purple red marks on her extremeties. She also has some signs of hirsutism that he did not notice on her previous visit several months ago.

Which of the following would correctly describe her primary acid-base disturbance?

A) Low pH, Low HCO3, High Base Deficit, Low pCO2.

B) Low pH, High HCO3, High Base Excess, High pCO2.

C) Neutal pH, Low HCO3, High Base Deficit, Low pCO2.

D) High pH, High HCO3, High Base Excess, High pCO2.

E) High pH, Low HCO3, High Base Excess, Low pCO2.

Explanation will be posted soon....
Answer is B, I think
Since she turned cushinoid from steroid therapy she would then suffer from obesity and restrained ventilation which should cause respiratory acidosis.
Am I right?
 

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Not sure

2) A 23-year-old man with rheumatic mitral regurgitation presents to your clinic with frequent palpitations and exercise intolerance. He is currently in no distress and other wise appears healthy. He is a current smoker and has a 10 pack-year smoking history. He has no history of diabetes and has never been hospitalized since he had rheumatic fever as a child.

Which one of the following is not an indicator of the severity of his mitral regurgitation?

A) Third heart sound
B) The loudness of the murmur.
C) Signs of heart failure.
D) Presence of thrill.
E) S4

Explanation will be posted soon....
I think S3 is not worrying in this case, but am not sure :notsure:
 

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Discussion Starter · #11 ·
I think S3 is not worrying in this case, but am not sure :notsure:
Thanks for answering laithbv. We are actually moving these questions to individual threads in the forums. Please feel free to post and answer on these new threads. I apologize for the confusion.
 
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