Primary FRCA Regional
Teaching Day - SBAs
Vivek Sinha
ST4 Anaesthetics
HRI
11/05/2013
Physiology
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1) A patient on the intensive care unit is being
ventilated in a volume-controlled mode with an FiO2
of 0.6. Arterial blood gas analysis reveals a PaO2 of
7.5kPa and a PaCO2 of 4.7kPa. Which ONE of the
following is the best intervention aimed at increasing
the PaO2?
a)
Increase the FiO2
b)
Increase the tidal volume
c)
Increase the frequency
d)
Increase the inspiratory time
e)
Increase the expiratory time
Physiology
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2) A hormone is produced in the cytoplasm of an
endocrine cell and is then stored in granules within
the cytoplasm. On release from the cell it is carried in
the blood-stream to a target cell, where it crosses the
cell membrane and binds directly to the nucleus,
increasing cell gene transcription. Which hormone is
best described in these terms?
a)
Adrenaline
b)
Thyroxine
c)
Aldosterone
d)
Thyroid-stimulating hormone
e)
Growth hormone
Explanation
3 main Classes of Hormone
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Peptides (eg. Growth Hormone)
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Synthesised in cell nucleus and then stored in granules and released by
exocytosis
Surface receptor
Act via second messengers
Amines
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Synthesised in the cytoplasm and then stored in granules
Two sub-types:
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Catecholamines (eg. adrenaline) – act at cell membranes and use second
messengers
Thyroid hormones (eg. Thyroxine) – binds directly to nucleus receptors,
stimulating transcription
Steroid (eg. Aldosterone)
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Synthesised from cholesterol
Immediately released (not stored)
Lipid-soluble
Enter cytoplasm and typically bind with receptors there and then enter
nucleus to stimulate transcription
Explanation
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Adrenaline & TSH – Gs protein-coupled
receptors
T3 & T4 stored in follicle stems between
thyroid cells as the protein thyroglobulin
33% Thyroxine (T4) converted to T3 in target
tissues and 45% to Reverse T3
T3 acts on nuclear receptors to alter cellular
function via messenger RNA
T4 has much less affinity to nuclear receptor
Explanation
Thyroid Follicular Cells
Physiology
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3) A patient with chronic obstructive pulmonary disease
presents for assessment for long-term oxygen therapy (LTOT)
and is found to have a compensated respiratory acidosis. Which
of the following sets of arterial blood gases best demonstrates
compensated respiratory acidosis?
a)
pH=7.30, PCO2=7.2kPa, PO2=9.5kPa, HCO3-=25mmol/L
b)
pH=7.36, PCO2=8.5kPa, PO2=7.5kPa, HCO3-=43mmol/L
c)
pH=7.24, PCO2=10.1kPa, PO2=7.0kPa, HCO3=27mmol/L
d)
pH=7.24, PCO2=3.5kPa, PO2=8.5kPa, HCO3-=18mmol/L
e)
pH=7.20, PCO2=6.2kPa, PO2=9.0kPa, HCO3-=15mmol/L
Physiology
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4) Which of the following statements regarding
humoral mechanisms involved in controlling
haemorrhage is INCORRECT?
a) Circulating catecholamines increase
b) Atrial natriuretic peptide (ANP) levels increase
c) Vasopressin release is mediated via the GauerHenry reflex
d) Stimulation of the adrenal cortex promotes release
of aldosterone
e) Circulating levels of enkephalins increase
Explanation
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Aldosterone
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Secreted by zona glomerulosa of adrenal cortex
Major regulators
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Renin-angiotensin system
Plasma concentration of potassium
ACTH
Miscellaneous regulators
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Sympathetic nerves
Baroreceptors
Plasma concentration of sodium
Aldosterone feedback
Explanation
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Enkephalins and endorphins
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Endogenous opioids that bind to and activate
opioid receptors throughout the CNS
Levels of enkephalins increased when adrenal
medulla is stimulated
Gauer-Henry reflex
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Atrial stretch sensors sense decrease in volume
and transmit signals to increase ADH secretion
Gravitational change from 1g to microgravity may
cause cephalad fluid shift, resulting in suppression
of ADH secretion and diuresis
Explanation
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ANP
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Plays important role in blood volume and electrolyte
homeostasis in normovolemia and in hypervolemic states
Secreted primarily from atria
Hypervolemia and elevation of left atrial pressure or volume
are the major known factors stimulating its release (local
wall stretch)
Plays important role in blood volume homeostasis by
inducing rapid natriuresis and water excretion
Lowers BP and antagonises renin-angiotensin-aldosterone
axis
Mild bleeding induces a rapid decrease in ANP secretion
Some studies show increased plasma ANP after prolonged
severe haemorrhage (possible biphasic effect of
haemorrhage)
Physiology
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5) A farmer slips and falls in a remote field during a
hot summer. He has nothing to eat and his only drink
is whisky from a hip flask. He is not found for 3 days.
On admission to hospital he is peripherally cold, with
a heart rate of 110 beats/min and a blood pressure
of 85/40mmHg. Which of the following is the most
potent stimulus for antidiuretic hormone release?
a)
Stimulation of central osmoreceptors
b)
Stimulation of aortic arch baroreceptors
c)
Ingestion of alcohol
d)
Pain
e)
Stress
Explanation
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Alcohol inhibits ADH
Pain and stress stimulate ADH
Osmoreceptors are very sensitive
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They respond to a change as small as a 1 to 2% increase in
tonicity
Baroreceptors are less sensitive (but more potent)
than the osmoreceptors
Hypovolaemia is a more potent stimulus for ADH
release than is hyperosmolality.
A hypovolaemic stimulus to ADH secretion will
override a hypotonic inhibition and volume will be
conserved at the expense of tonicity
Physiology
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6) Prior to induction of anaesthesia you
preoxygenate the patient with a Bain circuit
and a close fitting mask for 5 min. The
reason for this is:
a) To increase dissolved oxygen in the blood
b) To flush out nitrogen
c) To increase FRC
d) To increase oxygen Hg capacity
e) To increase the amount of oxygen in the
alveoli with 3l
Explanation
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Dissolved oxygen plays a tiny part in oxygen content
and transport compared to haemoglobin.
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100ml of arterial blood contains approximately 20ml of
oxygen, 19.7ml of which is combined with haemoglobin,
whereas only 0.3ml is dissolved in plasma.
In venous blood these figures are 14.9 and 0.1 respectively.
The oxygen content equation is as follows:
Oxygen content = (1.34 x Hb x sats)/100 +
0.023pO2,
where the Hb is measured in g/dl and the pO2 is
measured in kPa and the solubility coefficient of O2 is
0.023 ml/dl/kPa.
Explanation
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In normal person breathing room air with Hb
15g/dl, pO2 13.3kPa and sats 97%
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Even if the pO2 is increased to 80kPa
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Total arterial oxygen content would come to
19.80ml (bound to Hb = 19.497ml and dissolved
in plasma = 0.3059ml).
Total oxygen content would rise to only 21.337ml
(bound to Hb = 19.497ml and dissolved in plasma
= 1.84ml).
This is just a 1.08% rise in total oxygen content
Hyperbaric oxygen chamber
Explanation
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3L lung volume doesn't correlate with
any physiological lung measure and
alveoli is a very general term when you
discuss preoxygenation
Physiology
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7) A 78 year old patient has been admitted to the intensive care unit
for intubation and ventilation due to a low GCS. The family give a
history of progressive weakness over several weeks with abdominal
pain, decreased appetite, confusion and weight loss. The patient is
known to have ischaemic heart disease, peripheral vascular disease,
glaucoma, prostatic carcinoma and COPD. Blood results have come
back showing Hb 9, Platelets 90, WCC 13, Na 149, K 5.6, Ur 14, Cr
220, Ca 3.6. ECG shows a prolonged PR and prolonged QT.
What is the most likely cause of the ECG findings?
a) Congenital
b) Hypercalcaemia
c) Hyperkalaemia
d) Hypernatraemia
e) Myocardial Ischaemia
Explanation
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Very rare for a electrolyte abnormality to produce prolonged PR
and QT as well - as it needs both conduction and repolarisation
to be affected
Hypercalcaemia
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Range
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Normal serum corrected calcium = 2.1 – 2.6 mmol/L
Mild hypercalcaemia = 2.7 – 2.9 mmol/L
Moderate hypercalcaemia = 3.0 – 3.4 mmol/L
Severe hypercalcaemia = > 3.4 mmol/L
ECG
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Main ECG abnormality seen with hypercalcaemia is shortening of the
QT interval
ST segment duration shortened
In severe hypercalcaemia, Osborn waves (J waves) may be seen
Ventricular irritability and VF arrest has been reported with extreme
hypercalcaemia
Explanation
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Typical progressive changes of hyperkalaemia:
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Tall, pointed, narrow T waves.
Decreased P wave amplitude, decreased R wave height,
widening of QRS complexes, ST segment changes
(elevation/depression), hemiblock (esp. left anterior) and 1st
degree heart block.
Advanced intraventricular block (very wide QRS with RBBB,
LBBB, bi- or tri-fascicular blocks) and ventricular ectopics.
Absent P waves, very broad, bizarre QRS complexes, AV
block, VT, VF or ventricular asystole
No significant changes on the ECG occur with hypo/hypernatraemia
Pharmacology
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8) You are asked to provide anaesthesia for a
pregnant woman undergoing emergency
appendicectomy. Of the following drugs
administered to the woman, which is the
least likely to accumulate in the fetus?
a)
Bupivacaine
b)
Pethidine
c)
Thiopental
d)
Diamorphine
e)
Diazepam
Explanation
Physiochemical properties
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Increased placental transfer
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High lipid solubility (eg. Diazepam, most sedatives, pethidine)
MW (<600 dalton for lipid-soluble, <100 dalton for polar)
Bases (LAs & most opioids are weak bases)
Non-ionised (eg phenobarbital)
Low protein-binding
Decreased placental transfer
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Acids
Charged (eg. heparin)
Size (heparin, IgM)
Altered or bound by enzymes within placenta (eg. amines, insulin)
Firmly and highly bound to
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maternal RBC (eg. CO)
Plasma proteins (eg dicloxacillin, propranolol)
Explanation
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Basic drugs
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Fetal pH lower (0.1-0.15) than maternal pH
Relatively more ionized than in
maternal blood and "ion trapping" may occur,
leading to fetal drug accumulation
LAs, Pethidine
However, significant ion-trapping of bupivacaine
only occurs in significant acidosis
Pethidine
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Pethidine and Norpethidine (active metabolite of
pethidine) accumulates in both the mother and
fetus with a half-life of 4 and 20 hours
respectively in mother and 13 and 62 hours in
neonate
Explanation
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All used inhalational agents cross the placenta
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Thiopental, propofol, benzodiazepines and ketamine
all cross placenta but only benzodiazepines known to
produce significant fetal effects
Diamorphine
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Very little fetal depression if <1MAC & delivery occurs within
10min of induction
Rapidly eliminated by the placenta
Diamorphine, diazepam & pethidine broken down to
lipid-soluble products
Pharmacology
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9) A new drug is being tested. Its onset of action
depends on the rate of diffusion across the cell
membrane. The following factors increase the rate of
diffusion of a substance across a biological
membrane, EXCEPT which one?
a) Decreased molecular weight
b) Increased concentration gradient
c) Decreased solubility of a gas
d) Increased lipid solubility
e) For a weakly acidic substance, a low
environmental pH
Explanation
Factors Influencing Rate of Diffusion
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Graham’s Law
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Fick’s Law
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Rate of transfer proportional to concentration gradient
across membrane
Ionization
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Rate of passive diffusion is inversely proportional to square
root of molecular size
For acidic substance more unionized in lower pH
Lipid-solubility
Protein-binding
Rate of simple diffusion = permeability constant x
membrane area x concentration gradient
Pharmacology
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10) An adult patient distressed by shivering in
the postoperative period would be most
effectively treated with which ONE of the
following?
a)
Pethidine 25mg
b)
Doxapram 100mg
c)
Clonidine 150 µg
d)
Ketanserin 10mg
e)
Alfentanil 250 µg
Pharmacology
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11) After intravenous administration of anaesthesia
you notice the area around the injection site has
become very swollen, erythematous and inflamed.
Which of the following is most likely to cause most
damage?
a) Rocuronium
b) Morphine
c) Ondansetron
d) Dexamethasone
e) Thiopental
Explanation
Drugs used in anaesthesia/intensive care unit with potential to
cause tissue damage
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Acids/alkalis
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Hyperosmolar agents
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Calcium chloride
Calcium gluconate
Glucose >10%
Magnesium sulphate 20%
Mannitol 10% and 20%
Parenteral nutrition
Potassium chloride
Sodium bicarbonate
Sodium chloride >0.9%
X-ray contrast media
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Aminophylline
Amiodarone
Amphotericin
Co-trimoxazole
Diazepam
Erythromycin
Phenytoin
Thiopental
Vancomycin
Vascular regulators
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Epinephrine
Dobutamine
Dopamine
Metaraminol
Norepinephrine
Prostaglandin
Vasopressin
Contin Educ Anaesth Crit Care
Pain (2010) 10 (4): 109-113.
Pharmacology
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12) You are to carry out an experiment to assess the
speed of gastric emptying. A standard dose of a
marker drug is to be given to healthy volunteers. You
will then measure plasma drug concentration at
standard time intervals. Which of the following drugs
will be suitable for this:
a) Aspirin
b) Gentamicin
c) Paracetamol
d) Propranolol
e) Vancomycin
Explanation
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pH = pKa + log [BASE]/[ACID]
PKa of the drug (Dissociation or ionization constant):
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pH of the medium:
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Too much absorbed in stomach to be useful as marker
Still absorbed in small intestine despite low unionised fraction, due to large intestinal
surface area
Propranolol (weak base), pka= 9.4
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Affects ionization of drugs.
Weak acids  best absorbed in stomach.
Weak bases  best absorbed in intestine.
Aspirin (weak acid), pka=3.0
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pH at which half of the substance is ionized & half is unionized.
Absorbed mainly in small intestine
Extensive first-pass metabolism
Paracetamol (weak base), pKa=9.5
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Absorbed mainly in small intestine
Paracetamol absorption depends on gastric emptying
Low first-pass metabolism (approx 25%)
Pharmacology
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13) NIDDM patient had a 30 minute knee
arthroscopy. Pre-op BM 7. Given Ondansetron and
Dexamethasone for PONV. Post-op BM 13. What is
the most likely cause for raised BM post-op?
a) Dexamethasone
b) Ondansetron
c) Surgical stress
d) Missed morning dose of anti-diabetic medication
e) Metabolism of Hartmann's fluid
Pharmacology
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14) An asthmatic patient developed
bronchospasm from diclofenac. Which one of
the following could this be due to?
a) Thromboxane A2
b) Arachidonic acid
c) Leukotriene
d) Prostacyclin
e) Prostaglandin
Explanation
Pharmacology
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15) A 25 year old male has just been transferred to the operating table
for a repair of an umbilical hernia. After pre-oxygenation and induction
of general anaesthesia with thiopentone, fentanyl, mivacurium, an i-gel
was inserted and the patient was ventilated with IPPV. A bag of
gelofusine was being transfused and remifentanil and sevoflurane used
for maintenance of anaesthesia. A dose of teicoplanin was given for
surgical prophylaxis. 5 minutes into the surgery the patient develops
hypotension, bronchospasm, flushing.
Anaphylaxis was diagnosed and appropriate treatment was started.
What is the most likely cause of the anaphylaxis.
a) thiopentone
b) fentanyl
c) mivacurium
d) gelofusine
e) teicoplanin
Explanation
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Since 1980 more than 4,500 cases of perianaesthetic
anaphylaxis have been reported by French and
English authors.
The drugs most frequently responsible for
anaphylactic reactions in the French epidemiological
survey were
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NMBAs (54%)
Latex (22.3%)
Antibiotics (14.7%)
Opioid agents (2.4%)
Hypnotic agents (0.8%)
Colloids (2.8%)
Others (3%)
World Allergy Organization (WAO)
Explanation
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Among the cases of anaphylaxis attributed to NMBAs
in the literature, the following substances have been
incriminated, in decreasing order of importance:
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suxamethonium, vecuronium, atracurium, pancuronium,
rocuronium, mivacurium and cisatracurium.
If one expresses the number of reactions observed in
terms of the number of subjects exposed to NMBAs,
the drugs can be divided into 3 groups:
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those associated with a high frequency of allergic reactions,
including suxamethonium and rocuronium;
those associated with an intermediate frequency of allergy,
including vecuronium and pancuronium;
those associated with a low frequency of allergy, including
atracurium, mivacurium and cisatracurium.
World Allergy Organization (WAO)
Expanation
Causes of life-threatening allergic reactions during
anaesthesia
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Neuromuscular blocking agents (70%)
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Steroid-based compounds (vecuronium and pancuronium)
cause anaphylactic reactions, whereas benzylisoquinoliniums
(mivacurium and atracurium) tend to cause anaphylactoid
reactions.
Of drug reactions caused by neuromuscular blocking agents,
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43% are caused by succinylcholine,
37% vecuronium and
7% atracurium.
Latex (12.6%)
Colloids (4.7%)
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The risk is greatest with gelatin solutions.
All hyperosmolar solutions can release histamine directly.
Contin Educ Anaesth Crit Care
Pain (2004) 4 (4): 111-113.
Expanation
Causes of life-threatening allergic reactions during
anaesthesia
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Induction agents (3.6%)
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Antibiotics (2.6%)
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Penicillins most frequently implicated
Benzodiazepines (2%)
Opioids (1.7%)
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Incidence of severe reactions to thiopental been reported approx 1 in 14000
Reactions to propofol less common
Least common to etomidate
Opioids usually cause anaphylactic reactions; morphine implicated most
commonly.
Reactions to synthetic opioids rare
Morphine, codeine and meperidine can cause a dose-dependent, nonimmunological cutaneous histamine release
Other agents (2.5%)
Contin Educ Anaesth Crit Care
Pain (2004) 4 (4): 111-113.
Explanation
Incidence of anaphylaxis according to the NMBA in
France over 6 years ( 1997-2002 )
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Rocuronium
1 : 5,100 patients exposed
Succinylcholine
1 : 5,500 patients exposed
Vecuronium
1 : 13,000 patients exposed
Pancuronium
1 : 14,700 patients exposed
Mivacurium
1 : 38,200 patients exposed
Atracurium
1: 52,800 patients exposed
Cisatracurium
1 : 148,7000 patients exposed
Explanation
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Fentanyl
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Teicoplanin
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“To date, there have been seven reported cases of fentanylinduced anaphylaxis” (Br. J. Anaesth. (2011) 106 (2): 283-284)
“Anaphylactic Reactions: Uncommon - More than 1 in 1000 people
who have Teicoplanin” (NHS Choices website)
“Anaphylactic Shock: The frequency of these side-effects is
unknown” (NHS Choices website)
Gelofusine
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“Anaphylactoid reaction to Gelofusine, that contains succinylated
gelatin and other plasma expanders carries an estimated incidence
of 0.07–0.15%.” (Ioannis Polyzois et al. Anaphylaxis due to
gelofusine in a patient undergoing intramedullary nailing of the
femur: a case report. Cases Journal 2009, 2:12)
Physics & Measurement
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16) A 25-year-old woman who is 16 weeks pregnant
is admitted to hospital with sudden onset of
breathlessness and collapse. A transthoracic
echocardiogram suggests a massive pulmonary
embolus. An ECG is studied and shows sinus
tachycardia with right axis deviation. The cardiac axis
is likely to lie at which of these angles?
a)
-60 degrees
b)
+60 degrees
c)
+90 degrees
d)
+120 degrees
e)
-90 degrees
Explanation
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both I and aVF +ve = normal axis
both I and aVF -ve = axis in the Northwest Territory
lead I -ve and aVF +ve = right axis deviation
lead I +ve and aVF -ve
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lead II +ve = normal axis
lead II -ve = left axis deviation
Physics & Measurement
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17) Whilst checking the anaesthetic machine in
theatre you notice that a piece of monitoring
equipment has the symbol of a man enclosed in a
box. Which ONE of the following is not true regarding
the electrical safety of this equipment?
a) It is a floating circuit
b) It cannot be used in direct connection with the
heart
c) It has a maximal leakage current of 10 μA
d) It contains an isolating transformer
e) It has a maximal leakage current of 500 μA
Explanation
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This is the symbol for type BF equipment.
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Therefore has a maximal leakage current of 500 μA and
Cannot be used in direct connection with the heart
Equipment classified into 3 groups
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Class I equipment - any accessible conductible part must be
connected to earth
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Class II equipment has double or reinforced insulation of any
conductible parts
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For this system to work correctly, fuses must be present in the live and
neutral wires.
Does not have an earth wire.
Class III equipment uses batteries at a voltage unlikely to cause
electrocution
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But may result in microshock.
Davis PD, Kenny GNC. Basic
Physics and Measurement in
Anaesthesia, 5th edn. Oxford:
Butterworth Heinemann, 2003;
pp. 181-5.
Explanation
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Further classified by the maximum leakage current it
allows (type B, BF and CF).
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Type B or BF equipment is used in medical monitoring
equipment.
Type B has a maximum leakage current of 100–500 μA
under single fault conditions and should not be directly
connected to the heart.
It can be class I, II or III.
Type BF is type B but also uses a floating circuit.
Type CF has a floating circuit and a maximal leakage current
of 10–50 μA. It is used in equipment which may contact the
heart directly.
Davis PD, Kenny GNC. Basic
Physics and Measurement in
Anaesthesia, 5th edn. Oxford:
Butterworth Heinemann, 2003;
pp. 181-5.
Explanation
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Circuit breakers exist that are current-operated
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Consist of coils of the live wire around a transformer
An equal number of coils of the neutral wire are also wound
around the transformer
A third wire connects to a relay that operates the circuit
breaker
With equal currents in the live and neutral wire, the
magnetic fluxes are equal and opposite and therefore there
is no magnetic field.
With a small leakage current, the magnetic fluxes are
different, and a magnetic field that induces a current in the
third winding results in the relay breaking the circuit.
Davis PD, Kenny GNC. Basic
Physics and Measurement in
Anaesthesia, 5th edn. Oxford:
Butterworth Heinemann, 2003;
pp. 181-5.
Physics & Measurement
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18) Consider a hypothetical situation in which the
following gases or vapours are stored separately in
cylinders in a hot operating theatre (the thermometer
reads 35 degrees Celsius). Which one of the following
would NOT contain gas alone, irrespective of the
pressure within the cylinder?
a) Oxygen
b) Nitrogen
c) Nitrous oxide
d) Carbon dioxide
e) Air
Explanation
Nitrous Oxide Storage
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French blue cylinders
In a liquid phase with its vapour on top
At a gauge pressure of 4400 kPa at room temperature.
As the liquid is less compressible than a gas, the cylinder should
be only partially filled.
The filling ratio is weight of the fluid in the cylinder divided by
weight of water required to fill cylinder
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In the UK, the filling ratio for N2O is 0.75
But in hotter climates the filling ratio needs to be 0.67, to avoid
cylinder explosion.
Hospitals store N2O in large cylinders (e.g. size J) in two groups
of cylinder manifolds.
Physics & Measurement
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19) Capnography is part of the AAGBI minimal monitoring
requirements for general anaesthesia. Regarding capnography,
which of following is the LEAST correct?
a) Capnography is based on the principle that gases with two or
more different atoms in the molecule will absorb infrared
radiation
b) The particular frequency of infrared radiation is selected by
first passing it through a crystal window
c) A reference cell increases accuracy of the system
d) The use of infrared radiation with a wavelength of 4.28 µm
for the analysis of carbon dioxide should reduce interference
from the presence of nitrous oxide
e) In the sidestream capnograph, a sample is drawn at about
150mL/min
Explanation
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Basic analyser system consists of an infrared source,
sample chamber and detector
Basic principle of capnograph is based on Beer
Lambert Law
Beer Law
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Amount of infrared rays absorbed is proportional to the
concentration of the infrared absorbing substance
ie. The more CO2 present, the more infrared rays absorbed
The chamber is made of special material that freely
allows infrared waves to pass through (e.g.
sapphire).
Explanation
Explanation
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CO2 maximally absorbs infrared waves with
wavelengths of about 4.28 micrometers
Nitrous oxide maximally absorbs infrared
waves with wavelengths of about 4.5
micrometers
Collision Broadening
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Absorption pattern of CO2 broadens when N2O or
O2 added
Can lead to a potential source of error in
measurement
Modern analysers measure the amount of N2O
and O2 present to correct for errors due to
collision broadening.
Physics & Measurement
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20) A group of doctors from your hospital have recently
returned from a charity trip climbing Mount Everest. They are
relieved to be home as they said they couldn’t have a good cup
of tea on the mountain. Which of these responses would best
explain why?
a) The boiling point of water is 373.15 kelvin
b) The boiling point is the temperature of a substance at which
its saturated vapour pressure equals external atmospheric
pressure
c) A gas is a substance at a temperature above its critical
temperature
d) Boiling point increases with increasing pressure
e) The saturated vapour pressure of a substance increases with
increasing temperature
Physics & Measurement
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21) Arterial line pressure curve can
measure ventricular contraction by
a)
Dicrotic notch
b)
Area under the curve
c)
Wave upstroke
d)
Height of curve
e)
Length of curve
Explanation
Information in Arterial Waveform
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Arterial blood pressure
The slope of the upstroke of the wave reflects
myocardial contractility (dP/dt).
The stroke volume
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The position of the dicrotic notch on the down stroke.
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Calculated by measuring the area from the beginning of the
upstroke to the dicrotic notch.
If this is multiplied by the HR, then CO can be estimated.
A low dicrotic notch is seen in hypovolaemic patients.
The slope of the diastolic decay indicates resistance
to outflow (SVR).
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A slow fall is seen in vasoconstriction.
Physics & Measurement
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22) The potential difference across the capacitor
decreases, if the frequency of AC current increases.
What is the reason for this?
a) Capacitance inversely proportional to AC frequency
b) Impedence inversely proportional to AC frequency
c) Inductor inversely proportional to AC frequency
d) Resistance inversely proportional to AC frequency
e) Conductance inversely proportional to AC
frequency
Explanation
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Conductance = A measure of a material's ability to
conduct electric charge; the reciprocal of the
resistance
Resistance (R) = Opposition to current. (The part
which is constant regardless of frequency).
Reactance (X) = measure of the opposition of
capacitance and inductance to current.
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Reactance varies with the frequency of the electrical signal
Impedance (Z) = measure of overall opposition of a
circuit to current.

Takes into account both resistance and reactance.
Explanation
Explanation
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C=Q/V
Energy (E) needed to move an electric charge (Q) through a
p.d. (V):
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E= QV
As p.d. between plates increases more energy needed to add
extra charge
In DC circuit, current will flow initially and then die away as
capacitor becomes fully charged
In AC circuit, current will flow as capacitor being constantly
charged and discharged
AC frequency directly proportional to current size
R=V/I
AC frequency therefore inversely proportional to impedence
Physics & Measurement
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23) Long plastics operation approx 4 hours
long. Temp measured 34.5. No body warmer
or fluid warmer. What is the main reason for
the drop in temp:
a) iv fluids
b) convection
c) conduction
d) radiation
e) evaporation
Explanation

“Royal”
“College”
“Exam”
“Room”
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Conduction
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Radiation (~40%)
Convection (~30%)
Evaporation (8-15%)
Respiration (8-10%)
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Conduction (~5%)
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Clinical Scenario
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24) You are working as a ship’s doctor in the tropics. The ship rescues
a 40-year-old, 72 kg man from an island who was shipwrecked 2 days
previously. He has had nothing to eat or drink for 2 days and the
average daytime temperature has been 34 degrees Celsius. He looks
severely dehydrated but is conscious and cooperative. Which ONE of
the following would be your fluid resuscitation of choice over the next
24 hours?
a) Let him drink water freely
b) Cautiously allow to drink water and administer 2000mL of 5%
dextrose solution intravenously over the next 24 hours
c) Cautiously allow to drink water and administer 3000mL of
Hartmann’s solution intravenously over the next 24 hours
d) Prohibit oral fluids and administer 4000mL of 0.9% saline solution
intravenously over the next 24 hours
e) Prohibit oral fluids and administer 5000mL of dextrose saline
solution intravenously over the next 24 hours
Explanation
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Patient conscious and cooperative so
can be given mixture of oral + IV
rehydration
Just oral water will not replace lost
elecrolytes (neither will just 5%
dextrose)
Clinical Scenario
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25) You are required to take over an emergency laparotomy in a 54year-old, 80 kg male patient with a history of well-controlled
hypertension who is otherwise previously fit and well. You insert an
oesophageal Doppler probe and note the following haemodynamic
observations: heart rate103 beats/min, blood pressure 74/49 mmHG,
cardiac output 4.1 L/min, flow time corrected (FTc) 290 milliseconds.
Your initial management should be ONE of the following:
a)
Give a 200mL intravenous colloid bolus over 5 minutes
b)
Give a 200mL intravenous colloid bolus over 5 minutes and start
an intravenous infusion of dobutamine
c)
Give a 200mL intravenous colloid bolus over 5 minutes and start
an intravenous infusion of metaraminol
d)
Give a 200mL intravenous colloid bolus over 5 minutes and start
an intravenous infusion of noradrenaline
e)
Start an intravenous infusion of gliceryl trinitrate
Explanation
Explanation
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Reference ranges in adult with no comorbidities
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CO 5-8L/min
SV 60-100ml
PV
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20yrs: 90-120cm/s
50yrs: 70-100cm/s
70yrs: 50-80cm/s
FTc 330-360ms
Explanation
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Flow time
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Systolic ejection time
Will clearly vary according to heart rate, so to allow comparison,
corrected to HR of 60bpm (FTc)
FTc inversely related to SVR, therefore narrow waveform base
(<330ms) is indicator of vasoconstriction, of which hypovolaemia is
commonest cause
PV directly related to left ventricular contractility (agedependent)
An increase of SV or stroke distance of >10% would be seen as
positive response and challenge should be repeated
Concurrent shifts in FTc and PV indicates changes in afterload
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Increase in afterload gives simultaneous reduction in FTc and PV
(narrow waveform with decreased amplitude)
Explanation
Examples
Narrow waveform base, decreased FTc
characteristic of hypovolaemia
Explanation
Examples
Same patient after fluid resuscitation
Explanation
Examples
Explanation
Examples
Clinical Scenario
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26) Regarding the management of acute myocardial
infarction presenting with ischaemic symptoms and
persistent ST elevation, which ONE of the following
would be an absolute contraindication to fibrinolytic
therapy?
a) Previous fibrinolysis 5 months ago
b) Resuscitated cardiac arrest within the last hour
c) Diabetic retinopathy
d) Ischaemic stroke 2 months ago
e) Pregnant at 36 weeks gestation
Explanation
Absolute Contraindications
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Any prior ICH
Known structural cerebral vascular lesion (eg. AVM)
Known malignant intracranial neoplasm (primary or
metastatic)
Ischaemic stroke within 3 months EXCEPT acute
ischaemic stroke within 3 hours
Suspected aortic dissection
Active bleeding or bleeding diathesis (excluding
menses)
Significant closed-head or facial trauma within 3
months
2004 ACC/AHA Practice Guidelines
Explanation
Relative Contraindications
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History of chronic, severe, poorly-controlled HTN
Severe uncontrolled HTN on presentation (SBP >180mmHG or DBP
>100mmHg)
History of prior ischaemic stroke greater than 3 months, dementia, or
other known intracranial pathology
Traumatic or prolonged (>10min) CPR or major surgery (<3 weeks)
Recent internal bleeding (<2-4 weeks)
Noncompressible vascular punctures
Pregnancy
Active peptic ulcer
Current use of anticoagulants: the higher the INR, the higher the risk
of bleeding
For streptokinase: prior exposure (>5 days)
Prior allergic reaction to these agents
2004 ACC/AHA Practice Guidelines
Clinical Scenario
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27) You are fast bleeped to an elderly medicine ward to find a 84 year
old morbidly obese patient with weak respiratory effort on 15L nonrebreathe and a weak pulse with an unrecordable blood pressure. Just
as you try and assess the patient the patient stops breathing and you
call the cardiac arrest team and initiate CPR at 30 compressions to two
breaths. After one cycle the AED demonstrates VF and one shock is
administered. An i-Gel is inserted and the second cycle of CPR
commences. Peripheral IV access has proven difficult with multiple
attempts. What is your next action during this cycle of CPR?
a) Remove the i-Gel and perform tracheal intubation with an ETT tube
and give 1 mg Adrenaline down the Ett Tube
b) Give 1mg adrenaline IM
c) Attempt to gain central venous access and give 1 mg adrenaline
d) Give an intracardiac injection of adrenaline
e) Gain intraosseous access and give 1mg Adrenaline
Explanation
Resuscitation Council (UK) Guidelines 2010
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Delivery of drugs via a tracheal tube is no longer recommended
– if intravenous (IV) access cannot be achieved give drugs by
the intraosseous (IO) route.
When treating VF/VT cardiac arrest, adrenaline 1 mg is given
once chest compressions have restarted after the third shock
and then every 3-5 min (during alternate cycles of CPR).
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In the 2005 Guidelines, adrenaline was given just before the third
shock. This subtle change in the timing of adrenaline administration
is to separate the timing of drug delivery from attempted
defibrillation. It is hoped that this will result in more efficient shock
delivery and less interruption in chest compressions.
Amiodarone 300 mg is also given after the third shock.
Atropine is no longer recommended for routine use in asystole
or pulseless electrical activity (PEA).
Clinical Scenario
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28) You have anaesthetised a patient for a routine cystoscopy and
dilatation of urethral stricture. The patient is normally fit and well, is a
smoker and previous similar operations have been uneventful. You
have inserted a laryngeal mask airway and allowed the patient to
spontaneously breathe on a mixture of oxygen/air/desflurane.
Induction and transfer to theatre have been uneventful but10 minutes
into the procedure you notice the oxygen saturations reading 84%.
Attempted bag ventilation is impossible and you notice seesawing of
the abdomen. You diagnose laryngospasm tell the surgeon to stop.
what would be your next course of action.
a) Give 100% oxygen and increase your concentration of desflurane
and apply CPAP
b) Give a dose of alfentanil 1mg
c) Give 100% oxygen and give a bolus of propofol and apply CPAP
d) Give 100% oxygen and give a bolus of suxamethonium
e) Give 100% oxygen and apply CPAP
Clinical Scenario
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29) You have just induced your last patient on an elective
orthopaedic list. He is a 60 year old man for a bunionectomy of
left forefoot. You have used 200mg Propofol, 100 micrograms of
fentanyl and inserted an LMA and he is breathing spontaneously
on a mixture of oxygen/air/sevoflurane. His next blood pressure
is 76/30 with a heart rate of 56 bpm.
hat would you do next?
a) Give 600 micrograms atropine
b) Give 200 micrograms glycopyrrolate
c) Give metaraminol 0.5 mg
d) Give ephedrine 6 mg
e) Give a fluid challenge of 250 mls Hartmanns
Clinical Scenario
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30) A 42 year old female is undergoing a laparoscopic incisional
hernia repair for a large abdominal hernia developed after a
laparotomy for small bowel obstruction 12 months earlier.
During the surgery the patient develops high ventilation
pressures, desaturation, distended neck veins , hypotension,
reduced air entry and movement on the left side of the chest.
What should be the next step for this patient?
a) Endotracheal suction
b) Increasing PEEP
c) Increasing minute ventilation
d) Give muscle relaxant
e) Needle decompression and insertion of an intercostal chest
drain