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Question 1
Correct
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A pulmonary function tests results are: (Measurement, Predicted result, Test result). Forced vital capacity (FVC) (btps): 3.85, 2.36 Forced expiratory volume in 1 second (FEV1) (btps): 3.34, 0.97. FEV1/FVC ratio % (btps): 85.1, 39.9. Peak expiratory flow (PEF) (L/second): 7.33, 2.11. Maximum voluntary ventilation (MVV) (L/minute): 116, 44.4. What does this indicate?
Your Answer: Moderate restrictive and severe obstructive picture
Explanation:Severity of a reduction in restrictive defect (%FVC) or obstructive defect (V1/FVC) predicted are classified as follows:
Mild 70-80%
Moderate 60-69%
Moderately severe 50-59%
Severe 35-49%
Very severe <35%This patient has a mixed deficit with a severe obstructive deficit as V1/FVC predicted is 46.9% and a moderate restrictive deficit as %FVC of predicted is 61.3
FEV1/FVC ratio 80% < predicted and VC < 80% = mixed picture.
FEV1/FVC ratio 80% < predicted and VC > 80% = obstructive picture.
FEV1/FVC ratio 80% > predicted and VC > 80% = normal picture.
FEV1/FVC ratio 80% > predicted and VC < 80% predicted= restrictive picture.
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This question is part of the following fields:
- Clinical Measurement
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Question 2
Correct
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A 25-year old male with palpitations and dizziness presents to the emergency room. In the triage process, cardiac monitoring shows supraventricular tachycardia with a heart rate of 200 beats per minute. This high heart rate arises as a result of different specialised cells and nerve fibres in the heart which are responsible for conducting that action potential which is generated in the event of systole. The fastest conduction velocity is carried out by which of the following?
Your Answer: Purkinje fibres
Explanation:The correct answer is the Purkinje fibres, which conducts at a velocity of about 4m/sec.
The electrical conduction system of the heart starts with the SA node which generates spontaneous action potentials.
This is conducted across both atria by cell to cell conduction, and occurs at around 1 m/s. The only pathway for the action potential to enter the ventricles is through the AV node in a normal heart.
At this site, conduction is very slow at 0.05ms, which allows for the atria to completely contract and fill the ventricles with blood before the ventricles depolarise and contract.The action potentials are conducted through the Bundle of His from the AV node which then splits into the left and right bundle branches. This conduction is very fast, (,2m/s), and brings the action potential to the Purkinje fibres.
Purkinje fibres are specialised conducting cells which allow for a faster conduction speed of the action potential (,2-4m/s). This allows for a strong synchronized contraction from the ventricle and thus efficient generation of pressure in systole.
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This question is part of the following fields:
- Physiology And Biochemistry
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Question 3
Correct
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In the adrenal gland:
Your Answer: Catecholamine release is mediated by cholinergic nicotinic transmission
Explanation:The adrenal (suprarenal) gland is composed of two main parts: the adrenal cortex, which is the largest and outer part of the gland, and the adrenal medulla. The adrenal cortex consists of three zones: 1. Zona glomerulosa (outermost layer) is responsible for the production of mineralocorticoids, mainly aldosterone, which regulates blood pressure and electrolyte balance. 2. Zona fasciculata (middle layer) is responsible for the production of glucocorticoids, predominantly cortisol, which increases blood sugar levels via gluconeogenesis, suppresses the immune system, and aids in metabolism. It also produces 11-deoxycorticosterone and corticosterone in addition to cortisol. 3. Zona reticularis (innermost layer) is responsible for the production of gonadocorticoids, mainly dehydroepiandrosterone (DHEA), which serves as the starting material for many other important hormones produced by the adrenal gland, such as oestrogen, progesterone, testosterone, and cortisol. It is also responsible for administering these hormones to the reproductive regions of the body.
The adrenal medulla majorly secretes epinephrine (adrenaline), and norepinephrine in small quantity. Both hormones have similar functions and initiate the flight or fight response.
Catecholamine is mediated by cholinergic nicotinic transmission through changes in sympathetic nervous system (T5 – T11), being increased during stress and hypoglycaemia.
Blood supply to the adrenal gland is by these three arteries: superior suprarenal arteries, middle suprarenal artery and inferior suprarenal artery. Venous drainage is via the suprarenal vein to the left renal vein or directly to the inferior vena cava on the right side. There is no portal (venous) system between cortex and medulla.
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This question is part of the following fields:
- Anatomy
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Question 4
Incorrect
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An acidic drug with a pKA of 4.3 is injected intravenously into a patient. At a normal physiological pH, the approximate ratio of ionised to unionised forms of this drug in the plasma is?
Your Answer: 10,000:1
Correct Answer: 1000:01:00
Explanation:The pH at which the drug exists in 50 percent ionised and 50 percent unionised forms is known as the pKa.
To calculate the proportion of ionised to unionised form of an ACID, use the Henderson-Hasselbalch equation.
pH = pKa + log ([A-]/[HA])
or
pH = pKa + log [(salt)/(acid)]
pH = pKa + log ([ionised]/[unionised]).Hence, if the pKa ˆ’ pH = 0, then 50% of drug is ionised and 50% is unionised.
In this example:
7.4 = 4.3 + log ([ionised]/[unionised])
7.4 ˆ’ 4.3 = log ([ionised]/[unionised])
log 3.1 = log ([ionised]/[unionised])Simply put, the antilog is the inverse log calculation. In other words, if you know the logarithm of a number, you can use the antilog to find the value of the number. The antilogarithm’s definition is as follows:
y = antilog x = 10x
Antilog to the base 10 of 0 = 1, 1 = 10, 2 =100, 3 = 1000, and 4 = 10,000.
If you want to find the antilogarithm of 3.1, for a number between 3 and 4, the antilogarithm will return a value between 1000 and 10,000. The ratio is 1:1 if pKa = pH, that is, pH pKa = log 0. (50 percent ionised and unionised).
According to the above value, there is only one unionised molecule for every approximately 1000 (1259) ionised molecules of this drug in plasma, implying that this drug is largely ionised in plasma (99.99 percent ).
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This question is part of the following fields:
- Pharmacology
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Question 5
Correct
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An individual who recently moved his residence from the plains to the mountains will experience immediately which physiologic response to high altitude and hypoxia?
Your Answer: Increased cardiac output
Explanation:A person remaining at high altitudes for days, weeks, or years becomes more and more acclimatized to the low PO2, so it causes fewer deleterious effects on the body.
After acclimatization, it becomes possible for the person to work harder without hypoxic effects or to ascend to still higher altitudes. The principal means by which acclimatization comes about are (1) a great increase in pulmonary ventilation, (2) increased numbers of red blood cells, (3) diffusing capacity of the lungs, (4) increased vascularity of the peripheral tissues, and (5) increased ability of the tissue cells to use oxygen despite low PO2.
The cardiac output often increases as much as 30% immediately after a person ascends to high altitude but then decreases back toward normal over a period of weeks as the blood haematocrit increases, so the amount of oxygen transported to the peripheral body tissues remains about normal.
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This question is part of the following fields:
- Pathophysiology
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Question 6
Incorrect
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Many of the processes we deal with in anaesthesia entail a relationship between two or more variables. Which of the following relationships is a linear relationship?
Your Answer: The relationship between a decrease in plasma concentration of an intravenous bolus of a drug with time for a single compartment model
Correct Answer: The relationship between the junction potential and temperature in a thermocouple
Explanation:Two bonded wires of dissimilar metals, iron/constantan or copper/constantan, make up a thermocouple (constantan is an alloy of copper and nickel). At the tip, a thermojunction voltage is generated that is proportional to temperature (Seebeck effect).
All of the other connections are non-linear.
For a single compartment model, the relationship between a decrease in plasma concentration of an intravenous bolus of a drug and time is a washout exponential.
A sine wave is the relationship between current and degrees or time from a mains power source.
A sigmoid curve represents the relationship between efficacy and log-dose of a pure agonist on mu receptors.
The pressure of a fixed mass of gas and its volume (Boyle’s law) at a fixed temperature are inversely proportional, resulting in a hyperbolic curve.
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This question is part of the following fields:
- Anaesthesia Related Apparatus
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Question 7
Correct
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An 84-year-old woman has a fall. She fractures the neck of her femur and requires emergency surgery. On history and examination, she appears to also have a possible heart failure for which an echocardiogram is scheduled. Her measurements are: End-diastolic volume: 40mL (70-240), End-systolic volume: 30mL (16-140). Calculate her approximate ejection fraction.
Your Answer: 25%
Explanation:An echocardiogram provides real-time visualisation of cardiac structures. The ejection fraction (EF) is normally measured using this system.
The ejection fraction (EF) can be deduced mathematically if the patient’s end-diastolic volume (EDV), end-systolic volume (ESV) and stroke volume (SV) are known, as:
SV = EDV – ESV, and
EF = SV/EDV x 100
The normal range for EF is >55-70%.
For this patient,
SV= 40 – 30 = 10 mL, therefore
EF = 10/40 x 100 = 25%.
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This question is part of the following fields:
- Clinical Measurement
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Question 8
Correct
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A 30-year-old woman admitted following a tonsillectomy has developed stridor with a respiratory rate of 22 breaths per minute and obstructive movements of the chest and abdomen that is in a see-saw pattern . Her SpO2 is 92% on 60% oxygen with pulse rate 120 beats per minute while her blood pressure is 180/90mmHg. She is repeatedly trying to remove the oxygen mask and appears anxious. Her pharynx is suctioned and CPAP applied with 100% oxygen via a Mapleson C circuit. Which of these is the most appropriate next step in her management?
Your Answer: Administer intravenous propofol 0.5 mg/kg
Explanation:Continuous closure of the vocal cords resulting in partial or complete airway obstruction is called Laryngospasm. It is a reflex that helps protect against pulmonary aspiration.
Predisposing factors include: Hyperactive airway disease, Insufficient depth of anaesthesia, Inexperience of the anaesthetist, Airway irritation, Smoking, Shared airway surgery and Paediatric patients
Its primary treatment includes checking for blood or stomach aspirate in the pharynx, removing any triggering stimulation, relieving any possible supra-glottic component to airway obstruction and application of CPAP with 100% oxygen.
In this patient, all the above has been done and the next treatment of choice is the administration of a rapidly acting intravenous anaesthetic agent such as propofol (0.5 mg/kg) in increments as it has been reported to relieve laryngospasm in approximately 75% of cases. Administering suxamethonium to an awake patient would be inappropriate at this stage.
Magnesium and lidocaine are used for prevention rather than acute treatment of laryngospasm. Superior laryngeal nerve blocks have been reported to successfully treat recurrent laryngospasm but it is not the next logical step in index patient.
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This question is part of the following fields:
- Pathophysiology
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Question 9
Correct
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Which one of the following statement is true regarding United Kingdom gas cylinders?
Your Answer: Tensile tests are performed on sections of one cylinder in every hundred
Explanation:Medical gas cylinders are made up of molybdenum steel but not cast iron. They are checked and assessed at a regular interval.
At least one cylinder in each hundred are tested for tensile, pressure, smash, twist and straightening.
Nitrous Oxide cylinders contain a mixture of liquid and vapour at a pressure of approx. 4500 kPa or 45 Bar. Carbon dioxide cylinder contain gas at the pressure of 5000kPa.
The filling ratio is the ratio of mass of liquified gas in the cylinder to the mass of water required to fill the cylinder at the temperature of 15ºC. In the united kingdom, filling ratio of liquid nitrous oxide is 0.75. The cylinders are usually attached to the anaesthetic machine. As nitrous oxide is an N-methyl-d-aspartate receptor antagonist that may reduce the incidence of chronic post-surgical pain.
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This question is part of the following fields:
- Anaesthesia Related Apparatus
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Question 10
Incorrect
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When combined with a general anaesthetic or central neuraxial block, which of the following medications used to treat dementia involves the risk of significant hypotension?
Your Answer: Donepezil
Correct Answer: Risperidone
Explanation:Atypical antipsychotic drugs include risperidone and quetiapine. They not only inhibit dopamine receptors in the limbic system, but also histamine (H1) and alpha2 adrenoreceptors. When combined with general and/or central neuraxial block, this might result in severe hypotension.
Donepezil (Aricept) is an acetylcholinesterase (AChE) inhibitor that increases the neurotransmitter acetylcholine in the cerebral cortex and hippocampus in a reversible, non-competitive manner. It is used to reduce the advancement of Alzheimer’s disease symptoms (AD). Rivastigmine and galantamine are two more drugs that work in the same way.
Ginkgo Biloba contains anti-oxidant characteristics and is used to treat early-stage Alzheimer’s disease, vascular dementia, and peripheral vascular disease. It lowers platelet adhesiveness and decreases platelet activating factor (PAF) increasing the risk f bleeding, especially in individuals who are also taking anticoagulants and antiplatelet medication.
Memantine is an antagonist of the NMDA receptor. Synaptic plasticity, which is thought to be a critical component of learning and memory, can be inhibited at high doses. The use of ketamine is a relative contraindication since antagonism of this receptor can cause a dissociative state.
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This question is part of the following fields:
- Pharmacology
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Question 11
Correct
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Which type of epithelium lines the luminal surface of the oesophagus?
Your Answer: Non keratinised stratified squamous epithelium
Explanation:Normally, the oesophagus is lined by non-keratinized stratified squamous epithelium. This epithelium can undergo metaplasia and convert to the columnar epithelium (stomach’s lining) in long-standing GERD that leads to Barret’s oesophagus.
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This question is part of the following fields:
- Anatomy
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Question 12
Correct
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A single intravenous dose of 100 mg phenytoin was administered to a 70 kg patient and plasma concentration monitored. The concentration in plasma over time is recorded as follows: Time (hours): 1, 2, 3, 4, 5, Concentration (mcg/mL) 100, 71, 50, 35.5, 25. From the data available, the drug is likely eliminated by?
Your Answer: First-order kinetics with a half-life of 2 hours
Explanation:Elimination of phenytoin from the body follows first-order kinetics. This means that the rate of elimination is proportional to plasma concentration.
The rate of elimination can be described by the equation:
C = C0·e-kt
Where:
C = drug concentration
C0 = drug concentration at time zero (extrapolated)
k = Rate constant
t = TimeEnzyme systems become saturated when phenytoin concentrations exceed the normal range and elimination of the drug becomes zero-order. At this point, the drug is metabolised at a fixed rate and metabolism is independent of plasma concentration.
Aspirin and ethyl alcohol are other drugs that behave this way.
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This question is part of the following fields:
- Pharmacology
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Question 13
Correct
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Following a traumatic head injury, you are summoned to the emergency department to transfer a patient to the CT scanner. With a Glasgow coma score of 3, he has already been intubated and ventilated. It is important to ensure that cerebral protection strategies are implemented during the transfer. Which of the following methods is the most effective for reducing venous obstruction?
Your Answer: Position with a head-up tilt of 30°
Explanation:ICP is significant because it influences cerebral perfusion pressure and cerebral blood flow. The normal ICP ranges from 5 to 13 mmHg.
The components within the skull include the brain (80%/1400 ml), blood (10%/150 ml), and cerebrospinal fluid (CSF) (10%/150 ml).
Because the skull is a rigid box, if one of the three components increases in volume, one or more of the remaining components must decrease in volume to compensate, or the ICP will rise (Monroe-Kellie hypothesis).
Primary brain injury occurs as a result of a head injury and is unavoidable unless precautions are taken to reduce the risk of head injury. A reduction in oxygen delivery due to hypoxemia (low arterial PaO2) or anaemia, a reduction in cerebral blood flow due to hypotension or reduced cardiac output, and factors that cause a raised ICP and reduced CPP are all causes of secondary brain injury. Secondary brain injury can be avoided with proper management.
The most important initial management task is to make certain that:
There is protection of the airway and the cervical spine
There is proper ventilation and oxygenation
Blood pressure and cerebral perfusion pressure are both adequate (CPP).Following the implementation of these management principles, additional strategies to reduce ICP and preserve cerebral perfusion are required. The volume of one or more of the contents of the skull can be reduced using techniques that can be used to reduce ICP.
Reduce the volume of brain tissue
Blood volume should be reduced.
CSF volume should be reduced.The following are some methods for reducing the volume of brain tissue:
Abscess removal or tumour resection
Steroids (especially dexamethasone) are used to treat oedema in the brain.
To reduce intracellular volume, use mannitol/furosemide or hypertonic saline.
To increase intracranial volume, a decompressive craniectomy is performed.The following are some methods for reducing blood volume:
Haematomas must be evacuated.
Barbiturate coma reduces cerebral metabolic rate and oxygen consumption, lowering cerebral blood volume as a result.
Hypoxemia, hypercarbia, hyperthermia, vasodilator drugs, and hypotension should all be avoided in the arterial system.
PEEP/airway obstruction/CVP lines in neck: patient positioning with 30° head up, avoid neck compression with ties/excessive rotation, avoid PEEP/airway obstruction/CVP lines in neckThe following are some methods for reducing CSF volume:
To reduce CSF volume, an external ventricular drain or a ventriculoperitoneal shunt is inserted (although more a long term measure).
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This question is part of the following fields:
- Pathophysiology
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Question 14
Correct
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Drug toxicity when using bupivacaine is most likely to occur when this local anaesthetic technique is performed.
Your Answer: Intercostal nerve block
Explanation:An intercostal nerve block is used for therapeutic and diagnostic purposes. Intercostal nerve blocks manage acute and chronic pain in the chest area. Common indications are chest wall surgery and shingles or postherpetic neuralgia.
An intercostal nerve block is also an effective option for the management of pain associated with chest trauma and rib fractures. These blocks have been shown to improve oxygenation and respiratory mechanics, and offer pain relief that is comparable to that of epidural analgesia.
This technique, however, is limited by the relatively large doses of local anaesthetic required, and relatively high intravascular uptake from the intercostal space, increasing risk of local anaesthetic toxicity.
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This question is part of the following fields:
- Pharmacology
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Question 15
Correct
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The arterial-venous oxygen (a-vO2) difference is the difference between the oxygen content of arterial blood (CaO2) and mixed-venous blood (CvO2). At rest, which organ has the greatest a-vO2 difference?
Your Answer: Heart
Explanation:At rest, the heart has the greatest a-vO2 difference, a high capillary to myocyte ratio, short diffusion distances, and a high mitochondrial density. The flow of blood through the coronary arteries is also tightly controlled. At rest, 70-80 percent of the oxygen available to the cardiac muscle is extracted, increasing to 90 percent during exercise.
The a-vO2 difference indicates the body’s or an individual organ’s ability to extract oxygen from the blood.
CaO2 is influenced by a number of factors, including Hb concentration, PaO2 and pulmonary diffusion capacity.
CvO2 is influenced by a number of factors, including capillary density, regional blood flow, heart, resting skeletal muscle, kidney, intestine and skin.
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This question is part of the following fields:
- Pathophysiology
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Question 16
Correct
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Which of the following is the best associated option with Kaplan-Meier survival plot?
Your Answer: An estimate of decreasing survival with time after an event.
Explanation:Also known as the €œproduct limit estimate”, the Kaplan-Meier survival plot is used to estimate the true survival function from the collected data.
Using this plot, probabilities of occurrence of an event at a certain point in time can be computed. The successive probabilities are multiplied by any earlier computed probabilities to get the final estimate. For a given population, the survival probability at any particular time on the plot = (number of subjects living at the start – number of subjects who died)/number of subjects living at the start.
The description of a scatter plot is a graphical representation using Cartesian coordinates to display values for more than two variables for data set. It is used for to assess the relationship between 2 different variables.
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This question is part of the following fields:
- Statistical Methods
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Question 17
Correct
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The coronary sinus is a collection of veins joined together to form a large vessel that collects blood from the myocardium. Which structure forms the largest tributary of the coronary sinus?
Your Answer: Great cardiac vein
Explanation:The coronary sinus is large venous structure located on the posterior aspect of the left atrium, coursing within the left atrioventricular groove. The function of the coronary sinus is to drain the venous blood from the majority of the heart. It opens into the right atrium between the opening of inferior vena cava, the fossa ovalis and the right atrioventricular orifice. The coronary sinus is often guarded by a thin, semicircular endocardial fold, also known as the thebesian valve.
Tributaries include: Great cardiac vein, middle cardiac vein, small cardiac vein, posterior vein of left ventricle, oblique vein of left atrium. The great cardiac vein is the largest tributary of the coronary sinus. -
This question is part of the following fields:
- Anatomy
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Question 18
Incorrect
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The ED95 of muscle relaxants is the dose required to reduce twitch height by 95% in half of the target population. The dose of non-depolarizing muscle relaxants used for intubation is 2-3 times the ED95. For procedures that need a short duration of muscle relaxation and abrupt recovery, the short-acting drug Mivacurium is given at less than 2 times the ED95. What is the explanation for Mivacurium being an exception to this rule?
Your Answer: Mivacurium has a high potency
Correct Answer: Dose related histamine release occurs which frequently leads to tachycardia and hypotension
Explanation:Mivacurium, when administered at doses greater than 0.2 mg/kg,increases the risk for hypotension, tachycardia, and erythema. This is due to the ability of mivacurium to release histamine with increasing dose. Contrary to this fact, anaphylaxis is rare for mivacurium because of the short duration of histamine release.
The effective dose 50 (ED50) of mivacurium is between 0.08-0.15 mg/kg. It is administered slowly to prevent and decrease the risk of developing adverse effects.
Mivacurium has a high potency thus a longer duration of action, however this is not the answer that we are looking for.
Although drug metabolism takes longer for mivacurium than succinylcholine, it has no effect on the dose required for intubation.
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This question is part of the following fields:
- Pharmacology
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Question 19
Incorrect
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A sevoflurane vaporiser with a 2 percent setting and a 200 kPa ambient pressure is used. At this pressure, which of the following options best represents vaporiser output?
Your Answer: The output is 1% because the splitting ratio alters
Correct Answer: The output is 1% because the saturated pressure of sevoflurane is unaffected by ambient pressure
Explanation:Ambient pressure has no effect on a volatile agent’s saturated vapour pressure (SVP). At a temperature of 20°C, the SVP of sevoflurane is approximately 21 kPa, or 21% of atmospheric pressure (100 kPa).
The SVP of sevoflurane remains the same when the ambient pressure is doubled to 200 kPa, but the output of the vaporiser is halved, now 21 percent of 200 kPa, equalling 10.5 percent. The vaporiser’s output has increased to 1%, but the partial pressure output has remained unchanged. The splitting ratio will not change because it is determined by temperature changes.
Calculations can be made as follows:
Vaporizer output % (ambient pressure) = % volatile (calibrated) x 100 kPa calibrated pressure/ambient pressure
2% = 2% (dialled) × 100/100
2% of 100 = 2 kPaAltitude, pressure 50 kPa
4% = 2% (dialled) × 100/50
4% of 50 = 2 kPaHigh pressure at 200 kPa
1% = 2% (dialled) × 100/200
1% of 200 = 2 kPaSevoflurane has a boiling point of 58°C and, unlike desflurane (which has a boiling point of 22.8°C), does not need to be heated and pressurised with a Tec 6 vaporiser.
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This question is part of the following fields:
- Anaesthesia Related Apparatus
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Question 20
Correct
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Which term among the following is used for the proportion of a particular disease that would be eradicated from a population if the rate of disease were to be reduced to that of the group that has not been exposed to it?
Your Answer: Attributable proportion
Explanation:The attributable risk is the rate of a disease in an exposed group to that of a group that has not been exposed to it. It involves the measure of association that is pertinent to making decisions for the individuals.
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This question is part of the following fields:
- Statistical Methods
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