Primary MCQs-July 2010

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Primary MCQ papers

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GP21 [Feb04] [Jul10] All exist as racaemic mixtures except:

A. Thiopentone

B. Lignocaine

C. Bupivucaine

D. Isoflurane

E. Enflurane

Comparing dexamethasone and hydrocortisone:

A. Both are endogenous hormones

B. Dexamethasone has 25 times the potency of hydrocortisone

C. Both have mineralocorticoid activity

D. Dexamethasone is the only water-soluble compound

E. ?

GP29 Which of the following drugs cannot cross the BBB?

A. Ondansetron

B. Scopolamine

C. Metoclopramide

D. Droperidol

E. Domperidone

General Anaesthetics - Inhalational

Regarding desflurane, sevoflurane and isoflurane (not sure about the sequence/wording of answer stems)

A. All 3 ?inhibit mitochondrial K-ATPase
B. All 3 are degraded by soda lime into CO
C. Desflurane is not metabolised in the body to fluoride ions

Repeat question : MAC is changed/unchanged in ??

  • new*

With regards to the ratio of anaesthetic concentration at awareness to anaesthetic concentration required to prevent response to surgical stimulus (feel free to correct wrong answer stems, can't remember them well)

A. Ratio for nitrous oxide is higher than other volatile anaesthetics
B. Ratio for nitrous oxide is the same as other volatile anaesthetics
C. Propofol has a higher ratio compared to volatile anaesthetics
D. ?
  • Answer: A ... 0.4 MAC isoflurane prevents recall and responses to commands whereas nitrous oxide requires greater than 0.5 to 0.6 MAC to produce similar effects, (Stoelting 4th edition p 48)
  • Propofol requires a higher calculated end point concentration to prevent movement than it does to prevent awareness. But this is not MAC?

Toxic effects of inhalationals

A. Compound A not toxic to humans
B All inhalationals produce CO in soda lime

Nitrous oxide

A. Oxidises cobalt atom in vitamin B12
B Triggers MH
C. Oxidises methionine


A. MW greater than enflurane
B. ?

General Anaesthetics - Intravenous

Ketamine causes:

A. Bronchoconstriction
B. Myocardial depression
  • Answer: B

Ketamine causes bronchodilation and is a negative inotrope

REPEAT -Propofol is 98% protein bound

Emulsifier in propofol

A. Egg lethicin
B. Glycerol
C. Intralipid
  • Answer: A. "Current formulations of propofol use soybean oil as the oil phase and egg lecithin as the emulsifying agent that is composed of long chain triglycerides." (Stoelting 4th edition p 155)

Propofol clearance

A. Oxidation
B. Glucuronidation
C. ?

Local Anaesthetics

At least 3 questions about structure activity relationship of local anaesthetics

Muscle Relaxants & Antagonists

Graph showing Twitch height recovery 95% 25 min after 2x ED 95 dose

A. Atracurium
B. Suxamethonium
C. Mivacurium

Plasma cholinesterase deficiency greatest affect on

A. Esmolol
B. Mivacurium

Associated with ligand gated channels

A. Vecuronium
B. Opioids

Can't remember other options

Neostigmine works by

A. Carbamylation at esteratic site
B Hydrogen bonds at esteratic site
C Carbamylation at anionic site


A. Monoquaternary structure at phys pH

Major Analgesics/Opioids

No active metabolites

A. Morphine
B. Pethidine
C. Methadone

Most unlikely SE of morphine used for post-op pain

A. Nausea and vomit
B. Resp depression
C. Dependence

Fentanyl patch

A. After removal all eliminated from body in 17 hours
B Reaches steady state by 5 hours
C Releases 5mcg/hr
D. ?
  • After removal of fentanyl patch, time for serum fentanyl concentration to fall to 50% is 17 hour.
  • Time to reach steady serum levels after applying first patch is 12-24 hours.
  • Releases 12.5/25/50/75/100mcg per hour.
  • Reference: MIMs PI

Fentanyl rapid offset due to

A. Redistribution to non-active sites
B Uptake by lung


Psychotherapeutic Drugs

Action of anticonvulsants

A. Phenytoin works by keeping Na channels inactive
B. Vigabatrin MOA is inhibition of seratonin metabolism

Cardiovascular Drugs

Carvedilol for CCF because

Decrease renin release due to action at beta 2 receptor
B. ISA activity

Endocrine Drugs


Miscellaneous Drugs

G protein mediated only

A. Histamine
B. Seratonin
C. Ach

Not an example of ligand gated ion channel

A. Alpha 1 adrenoreceptor
B. Nicotinic receptor

Paracetamol causes

A. Haemorrhage
B. Renal failure
C. MetHb

Statistics & Drug Trials

Pearson R

A. Between 0 and 1
B. 0.75 = strong association

Answer from this would be B

  • Mild 0.2-0.4
  • Moderate 0.4-0.7
  • Strong 0.7-1.0

Ref: Myles and Gin page 80

Parametric tests preferred to non-parametric

A. Because they have greater power
B. Less alpha error
C. Less beta error
D. ?


Fluid & electrolytes

FE01 ECG Changes in hypokalaemia:

A. Prolonged QT
B. Depressed ST
C. Shortened QT
D. ?
E. ?

Acid-base physiology

AD08 During the infusion of a hydrochloric acid (HCl) infusion wich of the following contributes most to buffering?

A. Phosphate buffer
B. Intracellular buffers
C. Bicarbonate buffer
D. Proteins
E. ?

AD10 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

AD12 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

AD18 Base excess:

A. Calculated from PaCO2 40mmHg
B. ?
C. ?

Respiratory Physiology

RE67 What percentage of total blood volume is found in the pulmonary capillaries?

A. 1%
B. 3%
C. 9%
D. 11%
E. 15%


A. Production by Type 1 alveolar cells
B. Synthesis is slow
C. Acts like detergent in water
D Decreases pulmonary interstitial hydrostatic pressure

Hypoxaemia during anaesthesia is best fixed by

A. Increased pressure between breaths
B. Increased respiratory rate
C. Increased tidal volume
D. V/Q matcing

Altitude question (repeat) What would PAO2 be with PC02 40 when atmospheric pressure 248mmHg

A. 17 mmHg
B. 20 mmHg
C. 40 mmHg

Not possible: pAO2 = 0.21(248-47) - 40/0.8 = -7!!

RE66 A-a gradient of 50 mmHg due to

A. Hypoventilation
B. Venous admixture

RE70Anatomical dead space:

A. Increased with moving supine to erect
Can't remember other options

FRC reduced in anaesthesia by

A. Cephalad displacement of diapragm
B. Muscle relaxants
C. Age

CVS physiology

Example of autoregulation

A. Increased tissue vascularity
B. Renin angiotensin system
C. ?

What is 'Cardiac Efficiency'?

A. 20-30%
B. 31-40%
C. 41-50%
D. 51-60%
E. 61-70%

Answer = A

T Tubule in cardiac muscle

A. Z line
B. A band
C. H band

Answer = A

RE71 VO2 Max in a sedentary male (repeat)

A. 4
B. 11
C. 40

CV70 Repeat question about radial art trace v aorta

A. Peaks earlier
B. Bigger diacrotic notch

Question about MAP

A. Determined by area under arterial waveform
B. Determined by arteriolar resistance

Pulmonary wedge pressure

A. a but no c or v wave
B. a and c but no v wave
C. a, c and v wave

Renal physiology

KD38 Creatinine/urea is not used for the measurement of GFR because:

A. It is not readily filtered
B. It is secreted in the ascending loop of Henle
C. It is reabsorbed in the proximal tubule
D. ?
E. ?

What is Glomerular capillary hydrostatic pressure?

A. 20 mm Hg
B. 30 mm Hg
C. 40 mm Hg
D. 50 mm Hg
E. 60 mm Hg

Answer = E


A. Increases Na, K and H20 reabsorption
B. Increases Na and H20 reabsorption
C. ?
D. ?

GI physiology

What increases gastric pH?

B. Gastrin
C. Secretin

?Wording error? See GI09

Which of the following is NOT produced by the liver:

A. Immunoglobulins
B. Clotting Factors
C. Cholesterol
D. Conjugated Bilirubin
E. ?

Blood & immunology

FFP contains:

A. All pro-coagulants except platelets
B. Is treated to inactivate viruses
C. ?

Endocrine & metabolic physiology



Which spinal cord (Rexed) laminae do C-fibers synapse in?

A. I and II
B. I and IV
C. I and V
D. II and IV
E. II and V

Answer = A

Biggest concentration difference between plasma and CSF

A. Proteins
B. Potassium
C. Sodium

Answer = A

Physiology of muscle & NMJ

Smooth Muscle differs from Skeletal Muscle because:

A. It contains more mitochondria
B. It contains Troponin
C. It has a better developed Sarcoplasmic Reticulum
D. It has a higher ratio of Actin to Myosin
E. It contains fibers in a regular arrangement

Answer = D

Maternal, foetal & neonatal physiology

Hb Sats in Foetal IVC are:

A. 67%
B. 50%
C. 80%
D. 23%

(can't remember options correctly)

  • Power and Kam 2nd ed p.411 diagram - 67% in the IVC

Clinical measurement

What is NOT important when measuring Cardiac Output by oesophageal Doppler?

A. Haematocrit
B. Aorta Cross Sectional Area
C. Red Cell Velocity
D. Heart Rate
E. Red Cell Velocity

Answer = A I think, B & C are required to estimate SV, and HR required to calculate cardiac output using estimated stroke volume.

Clark electrode question:

A. Ag/Ag Cathode and Platinum anode
B. Can measure concentration in both blood and gas samples
C. Requires 0.6V applied to it (?wording)
D. ?

CM38 [Jul09] [Mar10] [Jul10]

Regarding Raman scattering:

A. The wavelength remains unchanged
B. It is a form of mass spectroscopy
C. ?... the emitted photon has the same wavelength
D. Only occurs with ?monoatomic molecule -OR- Can only be used to measure one gas at a time
E. Can be used to measure the concentration of a gas

CM39ECG R wave in V1 compared to V5

A. Bigger than
B. Smaller than
C. Proportional to
D. Not related
E. ?

Repeated question about pulse oximetry - Reading falsely ?high in

A. MetHb
B. Bilirubin
C. Methylene Blue
  • Answer = A. B should have no effect. C is the cure for A and underestimates SpO2 <--Disagree. MetHb pulls result towards 85%, so usually falsely low. Best answer not listed
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