Thread: MCQs : Acid-Base Disorders

MCQs : Acid-Base Disorders

Question 1

A 50-year-old homeless man was brought to the emergency room in a stuporous state. Blood pressure is 100/50 mmHg, heart rate 120 beats/min, respiratory rate 35/min, and his temperature is 104F (40C). He was found to have cellulitis of his left foot. Below are his lab results: Sodium 150mEq/L (135-145), Potassium 2.5mEq/L (3.5-5.0), Chloride 107mEq/L (95-105),Bicarbonate 10mEq/L (24-26), pH 7.2 (7.35-7.45), PCO2 25mmHg (35-45), Alcohol 40mmol/L (0), Osmolality 370mOsm/L (280-295), Glucose 50mg/dl (60-110) BUN 40mg/dl (5-22). What is the acid-base status?

a. metabolic acidosis and metabolic alkalosis
b. metabolic acidosis with partial respiratory compensation
c. respiratory acidosis and partial metabolic compensation
d. respiratory acidosis

Answer:

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The correct answer is: b
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Question 2

A 44-year-old man is brought to the emergency room stuporous and obtunded. He has not seen a physician previously and he takes no medication. Physical examination reveals BP 120/70 and pulse 90 (supine); and BP 90/50 and pulse 120 (standing). Serum chemistries are: Na+ = 140 mEq/L; Cl = 86 mEq/L; K+ = 2.9 mEq/L; HCO3 = 42 mEq/L; arterial pH = 7.5; PCO2 = 50mmHg. The disease process that best accounts for this problem

a. chronic obstructive pulmonary disease
b. congestive heart failure
c. protracted vomiting
d. renal failure

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The correct answer is: c
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Question 3

The medical student next to you, realizing that there is an examination question on acid base balance, begins nervously hyperventilating and then faints. You make him breathe into a paper bag and he recovers. If you had drawn and analysed his blood when he fainted you would have expected to see

a. decreased pH, decreased pCO2
b. decreased pH, decreased pCO2
c. elevated pH, decreased pCO2
d. elevated pH, elevated pCO2

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The correct answer is: c
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Question 4

A hospital patient with AIDS has large amount of diarrhea over the past 4 hours. He becomes hypovolemic over a short period of time. Which of the following lab results would best fit this clinical history?

a. pH: 7.15, pCO2: 55 mmHg, HCO3: 40 mEq/L
b. pH: 7.25, pCO2: 36 mmHg, HCO3: 15 mEq/L
c. pH: 7.40, pCO2: 40 mmHg, HCO3: 24 mEq/L
d. pH: 7.50, pCO2: 28 mmHg, HCO3: 24 mEq/L

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The correct answer is: b
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Question 5

A 28-year-old man with bronchiectasis presents to the hospital emergency room with 3 days of increasing cough, sputum, and dyspnea despite maximizing his bronchodilators. About 1 month ago, an outpatient stable room arterial blood gas showed pH 7.38, PaO2 55 mmHg, PaCO2 65 mmHg, and HCO3- 32 mEq/L. His current vital signs are BP 117/65 mmHg, P 123/min, T 100°F. His room air ABG in the ER is pH 7.28, PaCO2 70 mmHg, PaO2 50 mmHg, and HCO3- 23 mEq/L. Which of the following best characterizes the current acid-base status?

a. compensated metabolic acidosis
b. compensated metabolic alkalosis
c. uncompensated metabolic acidosis
d. uncompensated respiratory acidosis

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The correct answer is: d
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Question 6

The anion gap is calculated as follows:

a. [K+] + [HCO3- + Cl-]
b. [Na+] + [Cl- + HCO3-]
c. [Na+] – [HCO3- + Cl-]
d. This is typically machine derived so I will not have to calculate it.

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The correct answer is: c
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Question 7

The bicarbonate gap, calculated as Delta AG – Delta HCO3-, is a useful tool with mixed acid-base disorders because

a. If it is a positive a number it clearly indicates two respiratory problems.
b. If it’s negative, it clearly indicates one of the conditions is renal in origin.
c. If it’s positive or negative, it simply indicates I am dealing with a mixed problem.
d. It’s of no value at all and was simply cooked up to make my life miserable.

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The correct answer is: c
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Question 8

The so called proximal type of renal tubular acidosis, type 2 RTA, is characterized by

a. Reduced carbonate reabsorption and plasma bicarbonate levels between 12 and 20 mEq/L
b. Impaired renal tubular acidification and serum bicarbonate levels often below 10 mEq/L
c. High serum K+ levels
d. The loss of large amounts of protein and glucose.

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The correct answer is: a
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Question 9

The so called distal type of renal tubular acidosis, type 1 RTA, is characterized by

a. Reduced carbonate reabsorption and plasma bicarbonate levels between 12 and 20 mEq/L
b. Impaired renal tubular acidification and serum bicarbonate levels often below 10 mEq/L
c. High serum Na+ levels
d. Lack of response to aldosterone

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The correct answer is: b
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Question 10

Bob is a 64 year-old man who develops acute renal failure while recovering from a particularly bad MI. His labs are Na+ 140 mEq/L, K+ 4 mEq/L, Cl- 115 mEq/L, CO2 5 mEq/L, pH = 7.12, PaCO2 13 mmHg, and HCO3- 4 mEq/L. Calculate his bicarbonate gap and then choose the best answer that explains Bob's acid-base problem.

a. His bicarbonate gap of 14 indicates he has more than one reason for his acidosis.
b. His anion gap of 20 is conclusive evidence of a respiratory acidosis.
c. His delta bicarbonate of 22 strongly suggests an underlying GI problem.
d. None of this makes the remotest sense to me and I think Bob is malingering.

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The correct answer is: a
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Notes on Slides:

Acid-Base Balance and the Anion Gap

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http://medsci.indiana.edu/c602web/60...id_base_sl.pdf
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they are interesting but please anyone explaine me Q no 7 please
thanks

thank you

Thanks Boss.

Thank you!

thank u

great effort .thanks

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