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Question 1
Incorrect
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A 10-year-old girl complains of right iliac fossa pain, and a provisional diagnosis of appendicitis is made. Which of the following embryological structures gives rise to the appendix?
Your Answer: Vitello-intestinal duct
Correct Answer: Midgut
Explanation:The midgut gives rise to the appendix.
At week 6, the caecal diverticulum appears and is the precursor for the cecum and vermiform appendix. The cecum and appendix undergo rotation and descend into the right lower abdomen. The appendix can take up various positions:
1. Retrocecal appendix: behind the cecum
2. Retrocolic appendix: behind the ascending colon
3. Pelvic appendix: appendix descends into the pelvisThe appendix grows in length so that at birth, it is long and worm-shaped, or vermiform. After birth, the caecal wall grows unequally, and the appendix comes to lie on its medial side.
The midgut develops into the distal duodenum, jejunum, ileum, cecum, appendix, ascending colon, and proximal 2/3 of the transverse colon.
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This question is part of the following fields:
- Anatomy
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Question 2
Incorrect
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Regarding thermocouple, which of the following best describes its properties?
Your Answer: The measuring junction can be incorporated into a Wheatstone bridge
Correct Answer: The electromotive force at the measuring junction is proportional to temperature
Explanation:Thermocouples are based on the Seebeck effect, i.e. a small thermoelectric current is generated when two different metal wires are put into contact at both ends with their junctions having a different temperature. If one junction is open, a contact electromotive force is generated. The current, or the electromotive force, is to a first approximation proportional to the temperature difference ΔT between the two junctions. A better approximation is obtained with a MacLaurin expansion with the second power of ΔT.
Two wires bonded together with different coefficients of expansion can be used as a switch for thermostatic control.
The resistance at the measuring junction is irrelevant.
The resistance of a thermistor varies exponentially with temperature, while the resistance of a measuring junction varies linearly with temperature. Incorporated into a Wheatstone bridge is this unknown resistance, which is used to indirectly measure temperature.
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This question is part of the following fields:
- Basic Physics
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Question 3
Correct
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Modified rapid sequence induction with 1mg/kg rocuronium was done is a 42-year-old male for emergency appendicectomy. The patient weight was 70 kg and a failed intubation indicated immediate reversal of neuromuscular blockade. Which of the following is the correct dose of sugammadex for this patient?
Your Answer: 1120 mg
Explanation:Sugammadex is used for immediate reversal of rocuronium-induced neuromuscular blockade.
It is used at a dose of 16 mg/kg.Since the patient in the question is 70 kg, the required dose of sugammadex can be calculated as:
16×70 = 1120 mg.Sugammadex selectively binds rocuronium or vecuronium, thereby reversing their neuromuscular blocking action. Due to its 1:1 binding of rocuronium or vecuronium, it can reverse any depth of neuromuscular block.
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This question is part of the following fields:
- Pharmacology
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Question 4
Correct
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With regards to oxygen delivery in the body, which of these statements is true?
Your Answer: Anaemia will reduce oxygen delivery
Explanation:Oxygen delivery depends on 2 variables.
1) Content of oxygen in blood
2) Cardiac outputOxygen content (arterial) = (Hb (g/dL) x 1.39 x SaO2 (%) ) + (0.023 x PaO2 (kPa))
Oxygen content (mixed venous) = (Hb (g/dL) x 1.39 x mixed venous saturation) + (0.023 x mixed venous partial pressure of oxygen in kPA)
Huffner’s constant = 1.39 = 1g of Hb binds to 1.39 ml of O2
Oxygen delivery DO2 (ml/min) = 10 x Cardiac output (L/min) x Oxygen content
Normally 1000ml/minOxygen consumption VO2 (ml/min) = 10 x Cardiac output (L/min) x Difference in arterial and mixed venous oxygen content
Normally 250 ml/minOxygen extraction ratio (OER) = VO2/DO2
Normally approximately 25% -
This question is part of the following fields:
- Physiology And Biochemistry
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Question 5
Correct
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It was hypothesized that people that had lower socio economic status were more prone to developing gastric cancer. After 30 years of studying people with lower socio economic status, it was found that they did have a greater tendency to develop cancer. As a result of that the authors got to the conclusion that a strong association existed between the two. Later on another study conducted found that people from lower socio economic back grounds also had a tendency to be smokers. Which form of potential bias can be associated with this particular study?
Your Answer: Confounding bias
Explanation:Selection bias is when randomisation is not achieved and is often a result of in efficient recruiting method.
Recall bias is specifically appropriate to the case control studies that is when ever the memories retrieved by the participants differ in accuracy.
Measurement bias can be characterized by gathering of information in a manner that is distorted.
When the participants of a research study are recruited from the hospitals rather than the general population, its called Berkson Bias.
Confounding bias is the major player here because in this case the effects of smoking can be masked behind and can be read as outcomes of lower socio economic status. This extraneous factor (Smoking), distorts the founding.
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This question is part of the following fields:
- Statistical Methods
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Question 6
Correct
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A 25-year old lady is in the operating room and has had general anaesthesia for a knee arthroscopy. Induction was done with fentanyl 1mcg/kg and propofol 2mg/kg. A supra-glottic airway was inserted and using and air oxygen mixture with 2.5% sevoflurane, her anaesthesia was maintained. The patient is allowed to spontaneously breathe using a Bain circuit, and the fresh gas flow is 9L/min. Over the next 30 minutes, the end-tidal Co2 rises from 4.5kPa to 8.4kPa, and the baseline reading on the capnograph is 0kPa. The most appropriate initial action is which of the following?
Your Answer: Hypoventilation
Explanation:The commonest and most likely cause of a gradual rise in end-tidal CO2 (EtCO2) occurring during anaesthesia in a spontaneously breathing patient is hypoventilation. This occurs from the respiratory depressant effects of the opioid and sevoflurane.
Malignant hyperthermia should be sought if the EtCO2 shows further progressive rise.
Causes of rebreathing and a rise in the baseline of the capnograph can be caused by exhausted soda lime and inadequate fresh gas flow into the Bain circuit.
A sudden rise in EtCO2 can be caused deflation of the tourniquet.
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This question is part of the following fields:
- Physiology
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Question 7
Incorrect
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A 61-year-old woman with myasthenia gravis is admitted to the ER with type II respiratory failure. There is a suspicion of myasthenic crisis. She is in a semiconscious state. Her blood pressure is 160/90 mmHg, pulse is 110 beats per minute, temperature is 37°C, and oxygen saturation is 84 percent. With a PaCO2 of 75 mmHg (10 kPa) breathing air, blood gas analysis confirms she is hypoventilating. Which of the following values is the most accurate representation of her alveolar oxygen tension (PAO2)?
Your Answer: 8.5
Correct Answer: 7.3
Explanation:The following is the alveolar gas equation:
PAO2 = PiO2 ˆ’ PaCO2/R
Where:
PAO2 is the partial pressure of oxygen in the alveoli.
PiO2 is the partial pressure of oxygen inhaled.
PaCO2 stands for partial pressure of carbon dioxide in the arteries.
The amount of carbon dioxide produced (200 mL/minute) divided by the amount of oxygen consumed (250 mL/minute) equals R = respiratory quotient. With a normal diet, the value is 0.8.By subtracting the partial pressure exerted by water vapour at body temperature, the PiO2 can be calculated:
PiO2 = 0.21 × (100 kPa ˆ’ 6.3 kPa)
PiO2 = 19.8Substituting:
PAO2 = 19.8 ˆ’ 10/0.8
PAO2 = 19.8 ˆ’ 12.5
PAO2 = 7.3k Pa -
This question is part of the following fields:
- Physiology
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Question 8
Correct
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Metabolization of many drugs used in anaesthesia involves the cytochrome P450 (CYP) isoenzymes. The CYP enzyme most likely to be subject to genetic variability and thus cause adverse drug reactions is which of these?
Your Answer: CYP2D6
Explanation:Approximately 25% of phase-1 drug reactions is made responsible by CYP2D6.
As much as a 1,000-fold difference in the ability to metabolise drugs by CYP2D6 can happen between phenotypes, and this may result in adverse drug reactions (ADRs).
The metabolism of antiemetics, beta-blockers, codeine, tramadol, oxycodone, hydrocodone, tamoxifen, antidepressants, neuroleptics, and antiarrhythmics is also as a result of CYP2D6.
Patients who take drugs that are metabolised by CYP2D6 but have poor CYP2D6 metabolism are more likely to have ADRs. People with ultra-rapid CYP2D6 metabolism may have a decreased drug effect due to low plasma concentrations of these drugs.
All the other CYP enzymes are subject to genetic polymorphism. Variants are less likely to lead to adverse drug reactions.
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This question is part of the following fields:
- Physiology
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Question 9
Incorrect
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Which of the following drugs is safe to be used in porphyria?
Your Answer: Methohexitone
Correct Answer: Chloral hydrate
Explanation:Porphyria is a group of disorders in which there is excess production and excess excretion of porphyrins and their precursors. They are usually genetic and are caused due to defects in the haem metabolic pathway. However, other factors like infection, pregnancy, mensuration, starvation may precipitate the attack.
Sulphonamides, barbiturates (methohexitone and thiopental), and phenytoin are considered to be precipitants so are not safe to use
Chloral hydrate is thought to be safe to use.
Etomidate lacks proper studies and may be used with caution but it is generally advised not to use this drug especially if other alternatives are available. -
This question is part of the following fields:
- Pharmacology
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Question 10
Incorrect
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Which of the following is true about Calcium?
Your Answer: Chvostek's sign is when tapping the facial nerve causes facial muscle twitch/spasm
Correct Answer: Only 1% of total body Calcium is found in the plasma
Explanation:Only 1 percent of the calcium in the human body is found in the plasma where it performs the most critical functions.
Out of this 1 percent, approximately 15% is complexed calcium bound to organic and inorganic anions, 40% is bound to albumin, and the remaining 45% circulates as free ionized calcium.
The Chvostek sign is a clinical finding associated with hypocalcaemia, or low levels of calcium in the blood. This clinical sign refers to a twitch of the facial muscles that occurs when gently tapping an individual’s cheek, in front of the ear.
Prolonged QT interval are associated with hypocalcaemia as reported in multiple studies.
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This question is part of the following fields:
- Physiology And Biochemistry
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Question 11
Correct
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Which of the following is true about the patellar reflex?
Your Answer: Is abolished immediately after transection of the spinal cord at T6
Explanation:The patellar (knee jerk) reflex is a monosynaptic stretch reflex arising from L2-L4 nerve roots. It occurs after a tap on the patellar tendon which causes the spindles of the quadriceps muscles to stretch.
The afferent nerve pathway occurred through A gamma fibres.
Wesphal’s sign refers to a reduction, or absence of the patellar reflex. It is often indicated of a neurological disease affecting the PNS.
A transection of the spinal cord results in a degree of shock which causes all reflexes to be reduced or completely absent, and required a period of approximately 6 weeks to recover.
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This question is part of the following fields:
- Pathophysiology
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Question 12
Incorrect
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One litre of water at 0°C and a pressure of 1 bar is in a water-bath. A 1 kW element is used in heating it. Given that the specific heat capacity of water is 4181 J/(kg°C) or J/(kg K), how long will it take to raise the temperature of the water by 10°C?
Your Answer: 7 minutes
Correct Answer: 42 seconds
Explanation:The amount of energy required to change the temperature of 1 kg of a substance by 1°C is its specific heat capacity.
Energy required to increase the temperature of any object is given by the equation:
E = m × c × θ
Where:
E = energy required to heat an object
m = mass of object
c = specific heat capacity of the substance
θ = temperature changeThe specific heat capacity of water is 4181 J/(kg°C)
Therefore the energy required to raise 1kg of water by 10°C is:
1 kg × 4181 J/(kg°C) × 10°C = 41810 J
A 1 kW or 1000 W heater would be expected to supply 1000 J/s.
The approximate time it would take the 1 kW heater to raise the temperature of one Litre of water by 10°C is:
41810/1000 = 41.8 seconds.
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This question is part of the following fields:
- Physiology
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Question 13
Correct
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A 77-year-old woman is scheduled for day case cataract surgery under local anaesthesia. She has no cardiac or respiratory problems. Lisinopril is being used to treat her hypertension, which is under control. Which of the following preoperative investigations are the most appropriate for this patient?
Your Answer: No investigations
Explanation:Because the patient has mild systemic disease, he is ASA 2 and the procedure will be performed under local anaesthesia.
The following factors should be considered when requesting preoperative investigations:
Indications derived from a preliminary clinical examination
Whether or not a general anaesthetic will be used, the possibility of asymptomatic abnormalities, and the scope of the surgery.No special investigations are needed if the patient has no history of significant systemic disease and no abnormal findings on examination during the nurse-led assessment.
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This question is part of the following fields:
- Clinical Measurement
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Question 14
Correct
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A randomized study aimed at finding out the efficacy of a novel anticoagulant, in preventing stroke in patients suffering from atrial fibrillation, relative to those already available in the market was performed. A 59 year old woman volunteered for it and was randomised to the treatment arm. A year later, following findings were reported: 165 out of 1050 patients who were prescribed the already prevalent medicine had a stroke while the number of patients who had a single stroke after using the new drug was 132 out of 1044. In order to avoid one stroke case, what is the number of patients that need to be treated?
Your Answer: 32
Explanation:Number needed to treat can be defined as the number of patients who need to be treated to prevent one additional bad outcome.
It can be found as:
NNT=1/Absolute Risk Reduction (rounded to the next integer since number of patients can be integer only).
where ARR= (Risk factor associated with the new drug group) — (Risk factor associated with the currently available drug)
So,
ARR= (165/1050)-(132/1044)
ARR= (0.157-0.126)
ARR= 0.031
NNT= 1/0.031
NNT=32.3
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This question is part of the following fields:
- Statistical Methods
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Question 15
Correct
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Which of the following is true when testing for statistical significance?
Your Answer: The probability associated with a type I error is the significance level
Explanation:The null hypothesis states that there is no significant difference between two groups.
The alternative hypothesis states that there is a significant difference between two groups.
A type I error (false positive) occurs when a null hypothesis is rejected when it should be accepted.
A type II error (false negative) occurs when the alternative hypothesis is rejected when it should be accepted.
The probability determines the rejection of a null hypothesis.
The level of significance is set at p <0.05.
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This question is part of the following fields:
- Statistical Methods
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Question 16
Correct
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The incidence and prevalence of a diabetes in a locality are being measured by a health care professional. This is what he found: Year: People with Diabetes vs New Cases 2017: 150,000 vs 2000 2018: 150,000 vs 4000. What can be stated regarding the incidence and prevalence of the disease in that area?
Your Answer: Incidence increasing, prevalence equal
Explanation:Incidence tells us about the number of new cases that have been reported while prevalence gives us the idea of existing cases.
In this particular instance, the parameter of the study i.e. the total number of cases has not changed thus the prevalence of the disease remains same. Although, more cases have been reported in the second instance as a result of which incidence has increased.
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This question is part of the following fields:
- Statistical Methods
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Question 17
Incorrect
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All of the following options describes a thermistor for the measurement of temperature except:
Your Answer: Small bead of semiconductor material is incorporated in a Thermistor
Correct Answer: Resistance of the bead increases exponentially as the temperature increases
Explanation:There are different types of temperature measurement. These include:
Thermistor – this is a type of semiconductor, meaning they have greater resistance than conducting materials, but lower resistance than insulating materials. There are small beads of semiconductor material (e.g. metal oxide) which are incorporated into a Wheatstone bridge circuit. As the temperature increases, the resistance of the bead decreases exponentially
Thermocouple – Two different metals make up a thermocouple. Generally, in the form of two wires twisted, welded, or crimped together. Temperature is sensed by measuring the voltage. A potential difference is created that is proportional to the temperature at the junction (Seebeck effect)
Platinum resistance thermometers (PTR) – uses platinum for determining the temperature. The principle used is that the resistance of platinum changes with the change of temperature. The thermometer measures the temperature over the range of 200°C to1200°C. Resistance in metals show a linear increase with temperature
Tympanic thermometers – uses infrared radiation which is emitted by all living beings. It analyses the intensity and wavelength and then transduces the heat energy into a measurable electrical output
Gauge/dial thermometers – Uses coils of different metals with different co-efficient of expansion. These either tighten or relax with changes in temperature, moving a lever on a calibrated dial.
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This question is part of the following fields:
- Clinical Measurement
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Question 18
Correct
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A 240 volt alternating current (AC) socket from a wall is used to charge a direct current (DC) cardiac defibrillator. Name the electrical component that converts AC to DC.
Your Answer: Rectifier
Explanation:There are two types of defibrillators
AC defibrillator
DC defibrillatorAC defibrillator,
consists of a step-up transformer with primary and secondary winding and two switches. Since secondary coil consists of more turns of wire than the primary coil, it induces larger voltage. A voltage value ranging between 250V to 750V is applied for AC external defibrillator. And used to enable the charging of a capacitor.DC defibrillator,
consists of auto transformer T1 that acts as primary of the high voltage transformer T2. Is an iron core that transfers energy between 2 circuits by electromagnetic induction. Transformers are used to isolate circuits, change impedance and alter voltage output. transformers do not convert AC to DC.Diode rectifier composed of 4 diodes made of semiconductor material allows current to flow only in one direction. Alternating current (AC) passing through these diodes produces direct current (DC). Capacitor stores the charge in the form of an electrostatic field.
Capacitor is used to convert the rectified AC voltage to produce DC voltage but capacitors do not directly convert AC to DC.
Inductor induces a counter electromotive force(emf) that reduces the capacitor discharge value.
In step-down transformer primary coils has more turns of wire than secondary coil, so induced voltage is smaller in the secondary coil.
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This question is part of the following fields:
- Anaesthesia Related Apparatus
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Question 19
Incorrect
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A 64-year old lady has been diagnosed with hypertension. Her GP explains how this occurs, and that blood pressure is determined by multiple factors which include action by the heart, nervous system and the diameter of the blood vessels. This lady's cardiac output (CO) is 4L/min. Her exam today revealed a mean arterial pressure (MAP) of 140 mmHg. Using these values, her systemic vascular resistance (SVR) is which of these?
Your Answer: 560mmHg‹…min‹…mL-1
Correct Answer: 35mmHg‹…min‹…mL-1
Explanation:Impaired ventricular relaxation reduces diastolic filling and therefore preload.
Decreased blood volume decreases preload due to reduced venous return.
Heart failure is characterized by reduced ejection fraction and therefore stroke volume.
Cardiac output = stroke volume x heart rate
Left ventricular ejection fraction = (stroke volume / end diastolic LV volume ) x 100%
Stroke volume = end diastolic LV volume – end systolic LV volume
Pulse pressure (is increased by stroke volume) = Systolic Pressure – Diastolic Pressure
Systemic vascular resistance = mean arterial pressure / cardiac output
Factors that increase pulse pressure include:
-a less compliant aorta (this tends to occur with advancing age)
-increased stroke volume
Aortic stenosis would decrease stroke volume as end systolic volume would increase.
This is because of an increase in afterload, an increase in resistance that the heart must pump against due to a hard stenotic valve. -
This question is part of the following fields:
- Physiology And Biochemistry
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Question 20
Correct
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A 72-year-old woman with a medical history of ischaemic heart disease, hypertension, and hypothyroidism was brought to ER with a change in her mental state over the past few hours. Medications used by her were hydrochlorothiazide, aspirin, ramipril, and levothyroxine. On physical examination, decreased skin turgor, orthostatic hypotension, and disorientation of time and place were found. There were no significant neurological signs. Initial biochemical tests are as follows: Na: 111 mmol/L (135-145), K: 4.1 mmol/L (3.5-5.1), Cl: 105 mmol/L (99-101), Bic: 29 mmol/L (22-29), Urea: 16.4 mmol/L (1.7-8.3), Creatinine: 320µmol/L (44-80), Glucose: 13.5mmol/L (3.5-5.5), Plasma osmolality: 278mOsm/kg, Urinary osmolality: 450mOsm/kg, TSH: 6.2 miu/L (0.1-6.0), Free T4: 10.1 pmol/L (10-25), Free T3: 1.4nm/L (1.0-2.5), Which of the following is most likely cause for this condition of the patient?
Your Answer: Drug idiosyncrasy
Explanation:Based on the laboratory reports, the patient is suffering from significant hyponatremia. The symptoms of hyponatremia are mainly neurological and depend on the severity and rapidity of onset of hyponatremia.
Patient symptom according to the hyponatremia level is correlated below:
125 – 130mmol/L – Nausea and malaise
115 – 125mmol/L – Headache, lethargy, seizures, and coma
<120mmol/L – Up to 11% present with coma. -
This question is part of the following fields:
- Pathophysiology
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