Acid-base phys.txt

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Author:
freyerik
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110860
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Acid-base phys.txt
Updated:
2011-10-21 07:13:41
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acid base physiology
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MCQ's for physiology
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  1. Haemoglobin is a better buffer than plasma proteins because?

    a. present in much greater quanitity

    b. Hb contains 38 carboxyl residues

    c. plasma proteins have pKa closer to physiological pH
    • .
    • .
    • .
    • a. present in much greater quantity

    • NOT b - Hb contains 38 histadine resudues
    • NOT c - pKa of proteins...? 6.8
  2. Loss of 1 litre of pancreatic fluid-with normal fluid status causes?

    a. Hyperchloremic acidosis

    b. Every other wrong combination
    • .
    • .
    • .
    • a. Hyperchloremic acidosis
  3. Values measured directly from blood gas machine?

    a. Ph, p02, pco2

    b. other wrong combo's
    • .
    • .
    • .
    • a. PH, pO2, pco2
  4. During the infusion of a hydrochloric acid (HCl) infusion which of the following contributes most to buffering?

    A. Phosphate buffer

    B. Intracellular buffers

    C. Bicarbonate buffer

    D. Proteins

    E. ?
    • .
    • .
    • .
    • B or C – controversial. If just ECF – C, if both – possible B
  5. A patient is draining 1,5l from a pancreatic fistula per day whilst remaining of at a normal volume status. The most likely acid-base disorder is?

    A. Metabolic acidosis with a normal chloride

    B. Hypochloraemic metabolic acidosis

    C. Hyperchloraemic metabolic alkalosis

    D. Hyperchloraemic metabolic acidosis

    E. Hypochloraemic metabolic alkalosis
    • .
    • .
    • .
    • D. hyperchloraemic metabolic acidosis
  6. For the following blood gas results, which clinical scenario fits best?
    ABGs: pH 7.53, PCO2 26, HCO3 22

    A. Mountain climber after several weeks at altitude

    B. Chronic respiratory disease

    C. ?

    D. Hyperventilation for 5 minutes

    E. Prolonged vomiting
    • .
    • .
    • .
    • D. Hyperventilation for 5 minutes
  7. In plasma, a 'strong ion'?

    A. is usually a cation
    B. is usually an anion
    C. has its pKa close to 7.40
    D. almost completely dissociates
    E. ?
    • .
    • .
    • .
    • D. almost completely dissociates
  8. Base excess is?

    A. measured at a (? standard) pCO2 of 40mmHg

    B. is EQUAL to the difference between the measured bicarb and standard bicarb
    C. is always negative when pH > 7.40

    D. increases inversely with the bicarbonate level

    E. something wrong
    • .
    • .
    • .
    • A. measured at a (? standard) pCO2 of 40mmHg
  9. Why is phosphate such a good buffer in ICF and urine?

    A. ICF has lower pH than ECF (I'm pretty sure this was ICF has higher conc of phosphate than ECF actually)

    B. tubular pH is low

    C. pKa is close to pH

    D. concentration is high in urien and ICF (don't remember them asking about conc in the urine)

    E. all of above
    • .
    • .
    • .
    • E. all of above
  10. PO4 is a good intracellular buffer and tubular buffer because

    a. PKa is similar to intracellular pH

    b. intracellular concentration of PO4 higher

    c. tubular fluid concentration of PO4 higher

    d. Urine usually more acidic

    e. all of above
    • .
    • .
    • .
    • e. all of above
  11. pH 7.4. H+ concentration is

    a. 40 ummol/L
    b. 40 mmol/L
    c. 40 nmol/L
    d. 40 mg/L
    e. 40 ng/L
    • .
    • .
    • .
    • c. 40 nmol/L
  12. Addition of H+ to the following
    H+ + (HPO4)2- = H2PO4-

    a.
    b. increase in conjugate base
    c.
    d.
    e. decrease [HPO4 2-]
    • .
    • .
    • .
    • e. decrease [HPO4 2-]
  13. pH 6.96 pCO2 23 HCO3 5
    ABG is consistent with?

    a. ?
    b. ?
    c. diabetic coma
    d. ?
    e. prolonged vomiting
    • .
    • .
    • .
    • c. diabetic coma
  14. [Feb08] Calculation of Base Excess

    A. ? related to Henderson Hasselbalch equation
    B. Assumes a PCO2 of 40mmHg
    C. ?
    D. ?E. ?
    • .
    • .
    • .
    • b. assumes a PCO2 of 40mmHg
  15. [Feb08] A patient is draining 1 litre of fluid per day from a pancreatic fistula while maintaining normal volume status. The most likely acid-base disorder is:

    A. Hyperchloraemic metabolic acidosis
    B. Hypochloraemic metabolic acidosis
    C. Metabolic acidosis with normal chloride D. Hyperchloraemic metabolic alkalosis
    E. Hypochloraemic metabolic alkalosis
    • .
    • .
    • .
    • A. Hyperchloraemic metabolic acidosis
  16. [Feb08] Person with these blood gas results: pH 7.33 CO2 58 HCO3 33

    A. Acclimitization after several weeks at altitude

    B. Person with chronic pulmonary disease

    C. Diabetic ketoacidosis

    D. Hyperventilation

    E. Prolonged vomiting
    • .
    • .
    • .
    • B. Person with chronic pulmonary disease
  17. [Feb08] Person with these blood gas results: pH 7.53 pCO2 27 HCO3 22

    A. Acclimitization after several weeks at altitude

    B. Person with chronic pulmonary disease

    C. Diabetic ketoacidosis

    D. Hyperventilation

    E. Prolonged vomiting
    • .
    • .
    • .
    • D. Hyperventilation
  18. Which of the following is a 'strong ion'?

    A. PO4
    B. SO4
    C. Cl
    D. Albumin
    E. Propyl geline
    • .
    • .
    • .
    • C. Cl
    • Stewarts Strong Ion theory states that the difference between strong cations and anions, independently influences the pH of a solution.

    • and in human ECF is in the range 40-44. However Millers Anaesthesia also lists SO4 as a strong cation and (think sulfuric acid) so this could also be correct, but based on the formula above, chloride is the most correct.
    • i think SID = { [Na+] + [K+] + 2[Ca++] + 2[Mg++] } - { [Cl-] + [Other strong anions-] }
  19. Which of the following sets of values are measured directly by ABG machine

    A. pCO2, paO2, pH
    B. paCO2, HCO3, pH
    C. paCO2, base excess, paO2
    D. Something with base excess
    E. Something with HCO3
    • .
    • .
    • .
    • A. pCO2, paO2, pH
  20. Arterial Blood Gas Result -
    pH 7.56
    HCO3 43
    pCO2 53

    A. Mountaineer at altitude after a (week?)
    B.
    C.
    D. Hyperventilation
    E. Prolonged vomitting
    • .
    • .
    • .
    • E. Prolonged vomitting
  21. Base excess calculation from

    A. when PaCO2 is 40 mmHg

    B. difference of measured HCO3 from standard HCO3

    C. lower with higher HCO3

    D. is an indicator of cellular buffers

    E. is negative when pH greater than 7.40
    • .
    • .
    • .
    • A. when PaCO2 is 40 mmHg
  22. [Jul05] ABGs: pH 7.35, pCO2 60 mmHg, pO2 40 mmHg.
    These blood gas results are consistent with:

    A. Atelectasis

    B. Morphine induced respiratory
    depression (OR: Acute morphine overdose)

    C. Diabetic ketoacidosis

    D. Patient with COAD

    E. Lobar pneumonia (OR: bronchopneumonia)

    F. Metabolic acidosis

    (Alt version of the gas results: pH 7.35; pO2 45mmHg; pCO2 60mmHg; HCO3- 34mmol/l)
    • .
    • .
    • .
    • D. Patient with COAD
  23. The ABGs of a 60yr old man who has overdosed on morphine would be:

    A. paO2 60, paCO2 55, pH 7.29, HCO3 32, BE -1

    B. paO2 40, paCO2 60, pH 7.37, HCO3 26, BE +5

    C. ?
    • .
    • .
    • .
    • A. paO2 60, paCO2 55, pH 7.29, HCO3 32, BE -1
    • Not really correct – A would be correct if HCO3 was near normal
  24. Buffering of a bicarbonate infusion:

    A. 60 to 70% occurs intracellularly

    B. Exchanged for Cl- across the red cell membrane

    C. Compensated for by increased respiratory rate.

    D. Intracellular proteins
    • .
    • .
    • .
    • B. Exchanged for Cl- across the red cell membrane
  25. Phosphate buffer system is an effective buffer intracellularly and in renal tubules because:

    A. Its pKa is close to the operating pH

    B. High concentration in distal tubule

    C. High concentration intracellularly

    D. All of the above
    • .
    • .
    • .
    • D. All of the above
  26. Arterial gases including pH 7.46 bicarbonate 31mmol/l PCO2 46mmHg indicate:

    A. Metabolic alkalosis with respiratory compensation

    B. Respiratory alkalosis

    C. Respiratory acidosis with compensation

    D. Metabolic acidosis with respiratory compensation

    E. Mixed metabolic and respiratory alkalosis

    (Apr 01: AB05 changed so 2 top stems read partially compensated then bottom stem was "none of the above")
    • .
    • .
    • .
    • A. Metabolic alkalosis with respiratory compensation
  27. Metabolic acidosis is characterised by:

    A. Increased H+] intracellularly
    B. Decreased production of bicarbonate
    C. ?
    D. ?
    E. ?
    • .
    • .
    • .
    • A. Increased H+] intracellularly
  28. [Feb04]
    Bicarbonate system is the most important ECF buffer system because:

    A. It has a pKa close to physiological pH

    B. CO2 can be exchanged in lungs and HCO3 excreted in the kidneys

    C: HCO3- occurs in such large amounts

    D. ?

    E: CO2 can be regulated by lung & HCO3 by the kidneys
    • .
    • .
    • .
    • E: CO2 can be regulated by lung & HCO3 by the kidneys
    • pKa
    • Phosphate 6.8
    • HCO3- 6.1
    • Imidazole groups 6.8
    • Amino gp 9
    • Carboxyl gp 2 (?)
  29. In a patient with diabetic ketoacidosis, the following are true except:

    A. ?

    B. There is decreased PaCO2

    C. There is decreased concentration of H+ intracellularly

    D. Renal excretion of titratable acids will be increased

    E. There is increased synthesis of bicarbonate
    • .
    • .
    • .
    • C. There is decreased concentration of H+ intracellularly
  30. ABG's in healthy young man with pneumothorax:

    A. pO2=50, pCO2=25
    B. pO2=50, pCO2=46
    C. pO2=90, pCO2=25
    D. pO2=90, pCO2=46
    • .
    • .
    • .
    • ??????
  31. ABG of young male who develops total collapse of one lung postop:

    A. pO2 95mmHg pCO2 50 mmHg
    B. pO2 80mmHg pCO2 50mmHg
    C. pO2 90mmHg pCO2 25mmHg
    D. pO2 60mmHg pCO2 50mmHg
    • .
    • .
    • .
    • B. pO2 80mmHg pCO2 50mmHg
  32. [Jul10] For the following blood gas results, which clinical scenario fits best?
    2003 version:
    ABGs pH 7.48, PCO2 24 (or 26), HCO3 19 BE 15

    Jul10 version:
    ABGs: pH 7.53, PCO2 26, HCO3 22

    A. Mixed metabolic and respiratory acidosis

    B. Acute respiratory alkalosis

    C. Metabolic acidosis with compensated respiratory alkalosis

    D. Chronic respiratory disease

    E. Mountain climber after several weeks at altitude

    F. Hyperventilating consistent with acclimatisation to altitude

    G. Hyperventilation for 5 mins
    • .
    • .
    • .
    • B. Acute respiratory alkalosis
    • G. Hyperventilation for 5 mins
  33. A 26 year old female with the following ABG’s: pH 7.1, pCO2 11, pO2 110

    A. ?

    B. Metabolic acidosis with respiratory compensation

    C. ?
    • .
    • .
    • .
    • B. Metabolic acidosis with respiratory compensation
  34. [Feb04] A 19 year old is admitted unconscious. She has the with the following arterial blood gases:
    PaO2 117
    PaCO2 11
    pH 7.1
    BE -15

    This is most consistent with:

    A. Metabolic acidosis with respiratory compensation

    B. Respiratory alkalosis with metabolic
    compensation

    C. Mixed metabolic and respiratory acidosis

    D. ?
    • .
    • .
    • .
    • A. Metabolic acidosis with respiratory compensation
  35. Diabetic ketoacidosis:

    A. Causes increased intracellular H+
    • .
    • .
    • .
    • as above
  36. [Mar05] A previously healthy man with this blood gas:
    pH 7.40
    pCO2 50
    pO2 88

    Must indicate

    A. Breathing FIO2> 0.21

    B. Acute respirator acidosis

    C. Fully compensated metabolic acidosis

    D. HCO3 levels will be raised

    E. ?Mixed respiratory & metabolic acidosis
    • .
    • .
    • .
    • D. HCO3 levels will be raised
  37. [Mar05] A man is air lifted up to 5000m and his arterial blood gas is taken after ½ hr. He lives there and his blood gas is repeated after 1 week. Compared to the first sample, the second blood gas shows:

    A. No change in PaCO2 and PaO2

    B. PaCO2 increase, PaO2 increase

    C. PaCO2 increase, PaO2 decrease

    D. PaCO2 decrease, PaO2 decrease

    E. PaCO2 decrease, PaO2 increase
    • .
    • .
    • .
    • D. PaCO2 decrease, PaO2 decrease
  38. [Feb06]
    ABG: pH 7.48, PaO2 70, HCO3 raised (~35mmHg), PaCO2 48 (OR 58).

    This ABG could be explained by:

    A. Acclimatisation to altitude

    B. COAD

    C. Metabolic acidosis

    D. ?

    E. Prolonged vomiting
    • .
    • .
    • .
    • E. Prolonged vomiting
  39. [Feb08] Base excess calculation:

    A. When PaCO2 is 40 mm Hg

    B. Difference of measured HCO3 from standard HCO3

    C. Lower with higher HCO3

    D. Is an indicator of cellular buffers

    E. Is negative when pH is greater than 7.40
    • .
    • .
    • .
    • A. When PaCO2 is 40 mm Hg
  40. [Feb08] Person with these blood gas results: pH 7.33 CO2 58 HCO3 33

    A. Acclimitization after several weeks at altitude

    B. Person with chronic pulmonary disease

    C. Diabetic ketoacidosis

    D. Hyperventilation

    E. Prolonged vomiting
    • .
    • .
    • .
    • B. Person with chronic pulmonary disease
  41. [Feb08] Person with these blood gas results: pH 7.53 pCO2 27 HCO3 22

    A. Acclimitization after several weeks at altitude

    B. Person with chronic pulmonary disease

    C. Diabetic ketoacidosis

    D. Hyperventilation

    E. Prolonged vomiting
    • .
    • .
    • .
    • D. Hyperventilation

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