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Question 1
Correct
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What vessel is NOT considered a major branch of the descending thoracic aorta?
Your Answer: Inferior thyroid artery
Explanation:The descending thoracic aorta begins at the lower border of T4 near the midline as a continuation of the arch of the aorta. It descends and ends at the level of T12 at the aortic hiatus in the diaphragm, where it becomes the abdominal aorta.
The aorta gives off the following branches: (descending order)
1. Bronchial arteries
2. Mediastinal arteries
3. Oesophageal arteries
4. Pericardial arteries
5. Superior phrenic arteriesThe posterior intercostal arteries are branches that originate throughout the length of the posterior aspect of the descending thoracic aorta.
The inferior thyroid artery is usually derived from the thyrocervical trunk, a branch of the subclavian artery.
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This question is part of the following fields:
- Anatomy
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Question 2
Incorrect
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With a 10-day history of severe vomiting, a 71-year-old man with a gastric outlet obstruction is admitted to the surgical ward. The serum biochemical results listed below are available: Sodium 128 mmol/L (137-144), Potassium 2.6 mmol/L (3.5-4.9), Chloride 50 mmol/L (95-107), Urea 12 mmol/L (2.5-7.5), Creatinine 180 µmol/L (60-110). Which of the following do you think you are most likely to encounter?
Your Answer: Bicarbonate 45-50 mmol/L
Correct Answer: The standard base excess will be higher than actual base excess
Explanation:Hydrochloric acid is lost when you vomit for a long time (HCl). As a result, the following can be expected, in varying degrees of severity:
Hypokalaemia
Hypochloraemia
Increased bicarbonate to compensate for chloride loss and metabolic alkalosisThe alkalosis causes potassium to move from the intracellular to the extracellular compartment at first. Long-term vomiting and dehydration cause potassium to be excreted by the kidneys in order to conserve sodium. Dehydration can cause urea and creatinine levels to rise.
The actual base excess is always greater than the standard base excess.
The actual base excess (BE) is a measurement of a base’s contribution to a blood gas picture’s metabolic component. It’s the amount of base that needs to be added to a blood sample to bring the pH back to 7.4 after the respiratory component of a blood gas picture has been corrected (PaCO2 of 40 mmHg or 5.3 kPa). The BE has a normal range of +2 to 2. A large positive BE indicates a severe metabolic alkalosis, while a large negative BE indicates a severe metabolic acidosis. As a result, the actual BE in vitro is unaffected by CO2.
In vivo, however, standard BE is not independent of pCO2 because blood with haemoglobin acts as a better buffer than total ECF.
As a result, it is impossible to tell the difference between compensating for a respiratory disorder and compensating for the presence of a primary metabolic disorder.
The differences between in vitro and in vivo behaviour can be mostly eliminated if the BE is calculated for a haemoglobin concentration of 50 g/L (the ‘effective’ or virtual value of Hb if it was distributed throughout the extracellular space) rather than the actual haemoglobin. Because haemoglobin has a lower buffering capacity, the standard BE is higher than the actual BE. It reflects the BE better in the extracellular space rather than just the intravascular compartment.
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This question is part of the following fields:
- Pathophysiology
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Question 3
Correct
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A 26-year-old doctor has recently been diagnosed with lung cancer. He would like to find out his survival time for the condition. Which statistical method is used to predict survival rate?
Your Answer: Kaplan-Meier estimator
Explanation:The Weibull distribution are used to describe various types of observed failures of the components. it is used in reliability and survival analysis.
Regression Analysis is used to measure the relationship between among two or more variable. It determines the effect of independent variables on the dependent variables.
Student t-test is one of the most commonly used method to test the hypothesis. It determines the significant difference between the means of two different groups.
A time series is a collection of observations of well-defined data obtained at regular interval of time.
Kaplan-Meier estimator is used to estimate the survival function from lifetime data. It can be derived from maximum likelihood estimation of hazard function. It is most likely used to measure the fraction of patient’s life for a certain amount of time after treatment.
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This question is part of the following fields:
- Statistical Methods
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Question 4
Incorrect
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Which of the following statements is true regarding the relation to the liver?
Your Answer: Ligamentum venosum is an anterior relation of the liver
Correct Answer: The caudate lobe is superior to the porta hepatis
Explanation:Ligamentum venosum is an anterior relation of the liver: The ligamentum venosum, the fibrous remnant of the ductus venosus of the fetal circulation, lies posterior to the liver. It lies in the fossa for ductus venosus that separates the caudate lobe and the left lobe of the liver.
The portal triad contains three important tubes: 1. Proper hepatic artery 2. Hepatic portal vein 3. Bile ductules It also contains lymphatic vessels and a branch of the vagus nerve.
The bare area of the liver is a large triangular area that is devoid of any peritoneal covering. The bare area is attached directly to the diaphragm by loose connective tissue. This nonperitoneal area is created by a wide separation between the coronary ligaments.
The porta hepatis is a fissure in the inferior surface of the liver. All the neurovascular structures (except the hepatic veins) and hepatic ducts enter or leave the liver via the porta hepatis. It contains the sympathetic branch to the liver and gallbladder and the parasympathetic, hepatic branch of the vagus nerve. The caudate lobe (segment I) lies in the lesser sac on the inferior surface of the liver between the IVC on the right, the ligamentum venosum on the left, and the porta hepatis in front.
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This question is part of the following fields:
- Anatomy
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Question 5
Incorrect
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Which of the following is true about the patellar reflex?
Your Answer: Has a reflex arc which involves a single interneuron
Correct 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 6
Incorrect
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A patient admitted to the hospital is on oxygen via a venturi mask. The air entrainment ratio is 1:9 i.e. 1 litre of 100% oxygen from the source entrains 9 litres of air from the atmosphere). The flow rate of 100% oxygen is 6L/minute. Based on the given data which of the following value approximates the oxygen concentration delivered to the patient?
Your Answer: 35%
Correct Answer: 28%
Explanation:The formula for calculating air: oxygen entrainment ratio is given as :
100% ˆ’ FiO2 = air/oxygen entrainment ratio
Since FiO2 ˆ’ 21% and the entrainment ratio is already known. Substituting the values in the equation: x = FiO2.100 ˆ’ x = 9
x ˆ’ 21
100 ˆ’ x = 9(x ˆ’ 21)
100 ˆ’ x = 9x ˆ’ 189
10x = 289
x = 289/10
x = 28.9%. -
This question is part of the following fields:
- Basic Physics
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Question 7
Correct
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A new drug treatment has been developed for Crohn's disease. The pharmaceutical company behind this, is planning to conduct a trial and is looking for hiring around 200 individuals that are suffering from Crohn's disease. The aim would be to determine if there is any decline in the disease activity in response to the drug and compare it with a placebo. What phase is the trial in?
Your Answer: Phase 2
Explanation:The study is being conducted on a smaller level with only 200 participants and is determining the effectiveness of the drug in comparison to a placebo. These characteristics are in accordance with the second phase of trial.
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This question is part of the following fields:
- Statistical Methods
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Question 8
Incorrect
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All the following statements are false regarding gabapentin except:
Your Answer: Therapy is best monitored through measuring plasma concentrations
Correct Answer: Requires dose adjustment in renal disease
Explanation:Therapy with gabapentin requires dose adjustment with renal diseases. However, plasma monitoring of the drug is not necessary.
Gabapentin is not a liver enzyme inducer unlike other anticonvulsants like phenytoin and phenobarbitone
Gabapentin has not been shown to be associated with visual disturbances.
Gabapentin is used for add-on therapy in partial or generalized seizures and used in the management of chronic pain conditions but is of no use in petit mal.
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This question is part of the following fields:
- Pharmacology
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Question 9
Correct
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A 24-year old female is brought to the emergency room due to urticarial rash and shortness of breath. Her mother reported that, prior to the symptoms, she took Co-amoxiclav (Augmentin) for her present ear infection. She also reported that she had no previous exposure to penicillin or any other related antibiotics. Which of the following can help to differentiate between type 1 and type II hypersensitivity reaction in this case?
Your Answer: IgE assay specific for amoxycilloyl
Explanation:Serum specific IgE assays against allergen sources/molecules are the most commonly used in vitro diagnostic approach. The measurement of specific IgE recognizing allergenic epitopes can be achieved both through the usage of single reagents (singleplex) or with a pre-defined panel of a number of molecules to be tested simultaneously (multiplex).
Several clinical entities have been described and those occurring immediately after drug exposure are immunoglobulin E (IgE)-mediated and explored by skin testing and by the in vitro measurement of serum-specific IgE. The sensitivity of these tests is not 100% and even for patients with a clear positive history, a drug provocation test may be required in order to confirm the diagnosis. The advantages of the in vitro determination of specific IgE antibodies when compared with in vivo testing are that the former poses no direct risk to the patient and does not require personnel with expertise. Even though in vitro tests are recommended in immediate hypersensitivity reactions, their exact place in the diagnostic procedure is not clear and certain authors do not use this method in daily practice. In one study, in terms of sensitivity, 11 of 26 patients (42%) with negative skin tests and a positive drug provocation challenge (or repeated clinical history) had specific IgE to benzylpenicilloyl or amoxicilloyl (4). The specificity of the test was 95€“100%. Therefore, IgE measurements can avoid a potentially harmful drug provocation test.
An elevated serum tryptase does not differentiate between type 1 and type 2 hypersensitivity reaction. It indicates mast cell degranulation.
RAST is a useful aid to improve the overall diagnosis of drug allergies by using radioactive detection. This, however, is now rarely used.
Quantification of basophil activation by CD63 expression can be done by flow cytometry, which forms the basis of experimental drug-induced basophil stimulation tests.
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This question is part of the following fields:
- Pathophysiology
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Question 10
Correct
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This vertebrae can be easily differentiated from the rest because of its prominent spinous process.
Your Answer: C7
Explanation:The spinous process is the part of a vertebrae that is directed posteriorly.
Typical cervical vertebra have spinous processes that are small and bifid, except for C7, which has a long and prominent spinous process.
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This question is part of the following fields:
- Anatomy
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Question 11
Incorrect
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Which of the following is true regarding the dose of propofol?
Your Answer: 2-3 mg/kg
Correct Answer: 1-2mg/kg
Explanation:Propofol is a short-acting medication used for starting and maintenance of general anaesthesia, sedation for mechanically ventilated adults, and procedural sedation.
The dose of propofol is 1-2 mg/kg.Dose of some other important drugs are listed below:
Thiopental dose: 3-7 mg/kg
Ketamine dose: 1-2 mg/kg
Etomidate dose: 0.3 mg/kg
Methohexitone dose: 1.0-1.5 mg/kg -
This question is part of the following fields:
- Pharmacology
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Question 12
Incorrect
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What statement about endotoxins is true?
Your Answer: Elicit an antibody response which may protect the host from future attack
Correct Answer: Can often survive autoclaving
Explanation:Endotoxins are the lipopolysaccharides found in the outer cell wall of Gram-negative bacteria. They are responsible for providing the structure and stability of the cell wall.
They cannot be destroyed by normal sterilisation as they are heat stable molecules. They require the use of certain sterilant such as superoxide, peroxide and hypochlorite to be neutralised.
They stimulate strong immune responses, but can only be destroyed partially by specific antibodies. Repeat infections occur as memory T cells cannot be formed.
It can cause septicaemia and associated symptoms such as fever, shock, hypotension and nausea.
It activates the alternative complement pathway and the coagulation pathway using secreted cytokines.
It is not involved in botulism as clostridium botulinum, the responsible organism, secretes a neurotoxic exotoxin.
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This question is part of the following fields:
- Pathophysiology
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Question 13
Correct
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The physiological properties of a fast glycolytic (fast twitch) muscle fibre are characterised by which of the following?
Your Answer: Synthesis of ATP is brought about by anaerobic respiration
Explanation:Muscle fibre myosin ATPase histochemistry is used to divide the biochemical classification into two groups: type 1 and type II.
Type I (slow twitch) muscle fibres rely on aerobic glycolytic and aerobic oxidative metabolism to function. They have a lot of mitochondria, a good blood supply, a lot of myoglobin, and they don’t get tired easily.
Because they contain more motor units, Type II (fast twitch) muscle fibres are thicker. They are more easily fatigued, but produce powerful bursts. The capillary networks and mitochondria are less dense in these white muscle fibres than in type I fibres. They have a low myoglobin content as well.
Muscle fibres of type II (fast twitch) are divided into three types:
Type IIa – aerobic/oxidative metabolism is used.
Type IIb – anaerobic/glycolytic metabolism is used by these fibres.When compared to skeletal muscle, cardiac and smooth muscle twitch at a slower rate.
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This question is part of the following fields:
- Pharmacology
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Question 14
Incorrect
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All of the following statements about that parasympathetic nervous system (PNS) are true except:
Your Answer: Use Acetylcholine as the neurotransmitter
Correct Answer: The PNS has nicotinic receptors throughout the system
Explanation:With regards to the autonomic nervous system (ANS)
1. It is not under voluntary control
2. It uses reflex pathways and different to the somatic nervous system.
3. The hypothalamus is the central point of integration of the ANS. However, the gut can coordinate some secretions and information from the baroreceptors which are processed in the medulla.With regards to the central nervous system (CNS)
1. There are myelinated preganglionic fibres which lead to the
ganglion where the nerve cell bodies of the non-myelinated post ganglionic nerves are organised.
2. From the ganglion, the post ganglionic nerves then lead on to the innervated organ.Most organs are under control of both systems although one system normally predominates.
The nerves of the sympathetic nervous system (SNS) originate from the lateral horns of the spinal cord, pass into the anterior primary rami and then pass via the white rami communicates into the ganglia from T1-L2.
There are short pre-ganglionic and long post ganglionic fibres.
Pre-ganglionic synapses use acetylcholine (ACh) as a neurotransmitter on nicotinic receptors.
Post ganglionic synapses uses adrenoceptors with norepinephrine / epinephrine as the neurotransmitter.
However, in sweat glands, piloerector muscles and few blood vessels, ACh is still used as a neurotransmitter with nicotinic receptors.The ganglia form the sympathetic trunk – this is a collection of nerves that begin at the base of the skull and travel 2-3 cm lateral to the vertebrae, extending to the coccyx.
There are cervical, thoracic, lumbar and sacral ganglia and visceral sympathetic innervation is by cardiac, coeliac and hypogastric plexi.
Juxta glomerular apparatus, piloerector muscles and adipose tissue are all organs under sole sympathetic control.
The PNS has a craniosacral outflow. It causes reduced arousal and cardiovascular stimulation and increases visceral activity.
The cranial outflow consists of
1. The oculomotor nerve (CN III) to the eye via the ciliary ganglion,
2. Facial nerve (CN VII) to the submandibular, sublingual and lacrimal glands via the pterygopalatine and submandibular ganglions
3. Glossopharyngeal (CN IX) to lungs, larynx and tracheobronchial tree via otic ganglion
4. The vagus nerve (CN X), the largest contributor and carries ¾ of fibres covering innervation of the heart, lungs, larynx, tracheobronchial tree parotid gland and proximal gut to the splenic flexure, liver and pancreasThe sacral outflow (S2 to S4) innervates the bladder, distal gut and genitalia.
The PNS has long preganglionic and short post ganglionic fibres.
Preganglionic synapses, like in the SNS, use ACh as the neuro transmitter with nicotinic receptors.
Post ganglionic synapses also use ACh as the neurotransmitter but have muscarinic receptors.Different types of these muscarinic receptors are present in different organs:
There are:
M1 = pupillary constriction, gastric acid secretion stimulation
M2 = inhibition of cardiac stimulation
M3 = visceral vasodilation, coronary artery constriction, increased secretions in salivary, lacrimal glands and pancreas
M4 = brain and adrenal medulla
M5 = brainThe lacrimal glands are solely under parasympathetic control.
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This question is part of the following fields:
- Physiology And Biochemistry
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Question 15
Correct
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Regarding aldosterone, one of the following is true.
Your Answer: Secretion is increased following haematemesis
Explanation:Aldosterone is produced in the zona glomerulosa of the adrenal cortex and acts to increase sodium reabsorption via intracellular mineralocorticoid receptors in the distal tubules and collecting ducts of the nephron.
Its release is stimulated by hypovolaemia, blood loss ,and low plasma sodium and is inhibited by hypertension and increased sodium. It is regulated by the renin-angiotensin system.
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This question is part of the following fields:
- Pathophysiology
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Question 16
Incorrect
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A 19-year-old woman presents to the emergency department. She complains of symptoms indicative of an acute exacerbation of known 'brittle' asthma. On history, she reveals her asthma is normally controlled using inhalers and she has never had an acute exacerbation requiring hospitalisation. On her admission into the ICU, further examination and diagnostic investigations are conducted. Her readings are: Physical state: Alert, anxious and non-cyanotic. Respiratory rate: 30 breaths/min, Pulse: 120 beats/min, Blood pressure: 150/90 mmHg, SPO2: 95% on air. Auscultation: Quiet breath sounds at both lung bases. What is the next most important step of investigation?
Your Answer: Erect chest x ray
Correct Answer: Peak expiratory flow rate
Explanation:Peak expiratory flow rate (PEFR) is the maximum speed of air flow generated during a single forced exhaled breath. It is most useful when expressed as a percentage of the best value obtained from the patient.
Forced expiratory volume over 1 second (FEV1) is a lung parameter measured using spirometry. It is the amount of air forced out of the lung in one exhaled breath. It is a more accurate measure of lung obstructions as it doesn’t rely on effort like PEFR
PEFR and FEV1 are usually similar, but become more different in asthmatic patients as airflow becomes increasingly obstructed.
Acute severe asthma is most often diagnosed on history taking and examinations:
Respiratory rate: >25 breaths/min
Heart rate: >110 beats/min
PEFR: 33 – 50% predicted (<200L/min)
Patient state: Unable to complete a sentence in a single breath.A chest x-ray is not routinely required, and is only indicated in specific circumstances, which are:
If a pneumomediastinum or pneumothorax is suspected
Possible life threatening asthma
Possible consolidation
Unresponsive asthma
If ventilation is required.An echocardiograph (ECG) is not necessary in this case
Routine haematological and biochemical investigations are not urgent in this case as any abnormalities they detect will be secondary to the patient's presentation.
An arterial blood gas (ABG) will only be indicated if SPO2 was <92% or if patient presented with life threatening symptoms.
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This question is part of the following fields:
- Clinical Measurement
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Question 17
Incorrect
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A pharmaceutical company has developed a new drug considered a breakthrough in treating ovarian cancer. The efficacy of this drug can be assessed by which phase of a clinical trial?
Your Answer: Phase IIa
Correct Answer: Phase IIb
Explanation:Phase IIa studies are usually pilot studies designed to demonstrate clinical efficacy or biological activity (‘proof of concept’ studies) whereas phase IIb studies determine the optimal dose at which the drug shows biological activity with minimal side-effects (€˜definite dose-finding’ studies).
Phase III and Phase IV studies are performed on larger set of participants (usually hundreds to thousands) when safety and efficacy have been established.
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This question is part of the following fields:
- Statistical Methods
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Question 18
Incorrect
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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 obstructive and severe restrictive picture
Correct 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 19
Correct
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Regarding the emergency oxygen flush, which is true?
Your Answer: May lead to awareness if used inappropriately
Explanation:When the emergency oxygen flush is pressed, 100% oxygen is supplied from the common gas outlet. This gas bypasses BOTH flowmeters and vaporisers. The flow of oxygen is usually 45 l/min at a PRESSURE OF 400 kPa.
There is an increased risk of pulmonary barotrauma when the emergency flush is pressed, especially when anaesthetising paediatric patients.
The inappropriate use of the flush causes dilution of anaesthetic gases and this increases the possibility of anaesthetic awareness.
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This question is part of the following fields:
- Anaesthesia Related Apparatus
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Question 20
Incorrect
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Which of the following statement is not true regarding Adrenaline or Epinephrine?
Your Answer: Causes a lactic acidosis when continuously infused
Correct Answer: Inhibits Glucagon secretion in the pancreas
Explanation:Adrenaline acts on α1, α2, β1, and β2 receptors and also on dopamine receptors (D1, D2) and have sympathomimetic effects.
Natural catecholamines are Adrenaline, Noradrenaline, and Dopamine
Adrenaline is a sympathomimetic amine with both alpha and beta-adrenergic stimulating properties.
Adrenaline is the drug of choice for anaphylactic shock
Adrenaline is also used in patients with cardiac arrest. The preferred route is i.v. followed by the intra-osseous and endotracheal route.Adrenaline is released by the adrenal glands, acts on α 1 and 2, β 1 and 2 receptors, and is responsible for fight or flight response.
It acts on β 2 receptors in skeletal muscle vessels-causing vasodilation.
It acts on α adrenergic receptors to inhibit insulin secretion by the pancreas. It also stimulates glycogenolysis in the liver and muscle, stimulates glycolysis in muscle.
It acts on β adrenergic receptors to stimulate glucagon secretion in the pancreas. It also stimulates Adrenocorticotrophic Hormone (ACTH) and stimulates lipolysis by adipose tissue
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This question is part of the following fields:
- Pharmacology
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Question 21
Correct
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Which of the following causes the right-sided shift of the oxygen haemoglobin dissociation curve?
Your Answer: Chronic iron deficiency anaemia
Explanation:With respect to oxygen transport in cells, almost all oxygen is transported within erythrocytes. There is limited solubility and only 1% is carried as solution. Thus, the amount of oxygen transported depends upon haemoglobin concentration and its degree of saturation.
Haemoglobin is a globular protein composed of 4 subunits. Haem is made up of a protoporphyrin ring surrounding an iron atom in its ferrous state. The iron can form two additional bonds – one is with oxygen and the other with a polypeptide chain.
There are two alpha and two beta subunits to this polypeptide chain in an adult and together these form globin. Globin cannot bind oxygen but can bind to CO2 and hydrogen ions.
The beta chains are able to bind to 2,3 diphosphoglycerate. The oxygenation of haemoglobin is a reversible reaction. The molecular shape of haemoglobin is such that binding of one oxygen molecule facilitates the binding of subsequent molecules.The oxygen dissociation curve (ODC) describes the relationship between the percentage of saturated haemoglobin and partial pressure of oxygen in the blood.
Of note, it is not affected by haemoglobin concentration.Chronic anaemia causes 2, 3 DPG levels to increase, hence shifting the curve to the right
Haldane effect – Causes the ODC to shift to the left. For a given oxygen tension there is increased saturation of Hb with oxygen i.e. Decreased oxygen delivery to tissues.
This can be caused by:
-HbF, methaemoglobin, carboxyhaemoglobin
-low [H+] (alkali)
-low pCO2
-ow 2,3-DPG
-ow temperatureBohr effect – causes the ODC to shifts to the right = for given oxygen tension there is reduced saturation of Hb with oxygen i.e. Enhanced oxygen delivery to tissues. This can be caused by:
– raised [H+] (acidic)
– raised pCO2
-raised 2,3-DPG
-raised temperature -
This question is part of the following fields:
- Physiology And Biochemistry
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Question 22
Correct
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Seven days after undergoing an inguinal hernia repair, a 24-year old male presents with a wound that is erythematous, tender and has a purulent discharge. The most likely cause of this is which of the following?
Your Answer: Infection with Staphylococcus aureus
Explanation:Staphylococcus aureus infection is the most likely cause.
Surgical site infections (SSI) occur when there is a breach in tissue surfaces and allow normal commensals and other pathogens to initiate infection. They are a major cause of morbidity and mortality.
SSI comprise up to 20% of healthcare associated infections and approximately 5% of patients undergoing surgery will develop an SSI as a result.
The organisms are usually derived from the patient’s own body.Measures that may increase the risk of SSI include:
-Shaving the wound using a single use electrical razor with a disposable head
-Using a non iodine impregnated surgical drape if one is needed
-Tissue hypoxia
-Delayed prophylactic antibiotics administration in tourniquet surgery, patients with a prosthesis or valve, in clean-contaminated surgery of in contaminated surgery.Measures that may decrease the risk of SSI include:
1. Intraoperatively
– Prepare the skin with alcoholic chlorhexidine (Lowest incidence of SSI)
-Cover surgical site with dressingIn contrast to previous individual RCT’s, a recent meta analysis has confirmed that administration of supplementary oxygen does not reduce the risk of wound infection and wound edge protectors do not appear to confer benefit.
2. Post operatively
Tissue viability advice for management of surgical wounds healing by secondary intentionUse of diathermy for skin incisions
In the NICE guidelines the use of diathermy for skin incisions is not advocated. Several randomised controlled trials have been undertaken and demonstrated no increase in risk of SSI when diathermy is used. -
This question is part of the following fields:
- Physiology And Biochemistry
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Question 23
Correct
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During 2015 it was reported in the New England Journal of Medicine that the usage of empagliflozin(a sodium-glucose-co-transporter 2 inhibitor) caused a decrease in the cardiovascular deaths, non fatal heart attacks and strokes in patients suffering from type 2 diabetes. The results were published per 1000 patient years. With the above mentioned drug, the event rate turned out to be 37.3/1000 patient years whereas the placebo had an event rate of 43.9/1000 patient years. How many further patients need to be treated with empagliflozin to avoid any further incidence of cardiovascular death or non fatal myocardial infraction and non fatal stroke?
Your Answer: 150
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= (43.9-37.3)
ARR= 6.6
NNT= 1000/6.6
NNT=151.5
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This question is part of the following fields:
- Statistical Methods
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Question 24
Correct
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A radical neck dissection is being performed. The ENT surgeon wishes to expose the external carotid artery fully. He inserts a self-retaining retractor close to the origin of the external carotid artery. What structure lies posterolaterally to the external carotid at this point?
Your Answer: Internal carotid artery
Explanation:External carotid artery originates at the upper border of the thyroid cartilage. It ascends and lies anterior to the internal carotid arteries and posterior to the posterior belly of the digastric muscle and stylohyoid muscle.
The external carotid artery has eight important branches:
Anterior surface:
1. Superior thyroid artery (first branch)
2. Lingual artery
3. Facial artery
Medial branch
4. Ascending pharyngeal artery
Posterior branches
5. Occipital artery
6. Posterior auricular artery
Terminal branches
7. Maxillary artery
8. Superficial temporal artery. -
This question is part of the following fields:
- Anatomy
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Question 25
Correct
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At sea level, Sevoflurane is administered via a plenum vaporiser. 100 mL of the fresh gas flow is bypassed into the vaporising chamber. Temperature within the vaporising chamber is maintained at 20°C. The following fresh gas flows approximates best for the delivery of 1% sevoflurane.
Your Answer: 2.7 L/minute
Explanation:The equation for calculating vaporiser output is:
Vaporiser output (VO) mL = Carrier gas flow (mL/minute) × SVP of agent (kPa)
Ambient pressure (kPa) ˆ’ SVP of agent (kPa)The saturated vapour pressure of sevoflurane at 1 atm (100 kPa) and 20°C is 21 kPa.
VO = (100 mL × 21 kPa)/(100 kPa ˆ’ 21kPa) for sevoflurane,
VO = 26.6 mL26.6 mL of 100% sevoflurane and 100 mL bypass carrier gas is being added to the fresh gas flow per minute.
2660 mL of 1% sevoflurane and 100 mL bypass carrier gas is approximately 2.7 L/minute.
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This question is part of the following fields:
- Pharmacology
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Question 26
Correct
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Which of the following statements is true about data analysed from a new drug trial?
Your Answer: The data could be evaluated using the chi square test
Explanation:The data is ideal for chi square test evaluation as it will help determine if observed outcomes are in line with expected outcomes, and also if results are significant or due to chance.
The student’s t test is not ideal as it requires comparison of means from different populations, rather than proportions.
Pearson’s coefficient of linear regression is not ideal as it requires the plotting of a linear regression.
The numbers should be analysed before determining if there are any statistical conclusions that can be drawn from the population.
Statistical analysis is always required to determine the performance of any treatment during a clinical drug trial. Conclusions cannot be drawn simply by looking at the data.
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This question is part of the following fields:
- Statistical Methods
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Question 27
Correct
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A 30-year old lady has a sub total thyroidectomy. On the 5th post-operative day, the wound becomes erythematous and there is a purulent discharge. The most likely organism causing this is:
Your Answer: Staphylococcus aureus
Explanation:Staphylococcus aureus infection is the most likely cause.
Surgical site infections (SSI) occur when there is a breach in tissue surfaces and allow normal commensals and other pathogens to initiate infection. They are a major cause of morbidity and mortality.
SSI comprise up to 20% of healthcare associated infections and approximately 5% of patients undergoing surgery will develop an SSI as a result.
The organisms are usually derived from the patient’s own body.Measures that may increase the risk of SSI include:
-Shaving the wound using a single use electrical razor with a disposable head
-Using a non iodine impregnated surgical drape if one is needed
-Tissue hypoxia
-Delayed prophylactic antibiotics administration in tourniquet surgery, patients with a prosthesis or valve, in clean-contaminated surgery of in contaminated surgery.Measures that may decrease the risk of SSI include:
1. Intraoperatively
– Prepare the skin with alcoholic chlorhexidine (Lowest incidence of SSI)
-Cover surgical site with dressingIn contrast to previous individual RCT’s, a recent meta analysis has confirmed that administration of supplementary oxygen does not reduce the risk of wound infection and wound edge protectors do not appear to confer benefit.
2. Post operatively
Tissue viability advice for management of surgical wounds healing by secondary intentionUse of diathermy for skin incisions
In the NICE guidelines the use of diathermy for skin incisions is not advocated. Several randomised controlled trials have been undertaken and demonstrated no increase in risk of SSI when diathermy is used. -
This question is part of the following fields:
- Physiology And Biochemistry
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Question 28
Correct
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The following is true about the extracellular fluid (ECF) in a normal adult woman weighing 60 kg.
Your Answer: Has a total volume of about 12 litres
Explanation:Total body water (TBW) is about 50% to 70% in adults depending on how much fat is present. ECF is relatively contracted in an obese person.
The simple rule is 60-40-20. (60% of weight = total body water, 40% of body weight is ICF and 20% is ECF)
For this woman, the total body water is 36 litres (0.6 × 60). ECF is 12 litres (1/3 of TBW) and 24 litres (2/3 of TBW) is intracellular fluid .
Sodium concentration is approximately 135-145 mmol/L in the ECF.
The ECF is made up of both intravascular and extravascular fluid and plasma proteins is found in both.
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This question is part of the following fields:
- Physiology
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Question 29
Incorrect
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Which statement regarding the cardiac action potential is correct?
Your Answer: Phase 4 is repolarization due to potassium efflux after calcium channels close
Correct Answer: Phase 2 is the plateau phase with large influx of calcium ions
Explanation:Cardiac conduction
Phase 0 – Rapid depolarization. Opening of fast sodium channels with large influx of sodium
Phase 1 – Rapid partial depolarization. Opening of potassium channels and efflux of potassium ions. Sodium channels close and influx of sodium ions stop
Phase 2 – Plateau phase with large influx of calcium ions. Offsets action of potassium channels. The absolute refractory period
Phase 3 – Repolarization due to potassium efflux after calcium channels close. Relative refractory period
Phase 4 – Repolarization continues as sodium/potassium pump restores the ionic gradient by pumping out 3 sodium ions in exchange for 2 potassium ions coming into the cell. Relative refractory period
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This question is part of the following fields:
- Physiology And Biochemistry
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Question 30
Incorrect
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All of the following statements are true regarding calcium except:
Your Answer: Hypocalcaemia may cause cardiac failure
Correct Answer: Serum calcium accounts for 10% of total body calcium stores
Explanation:Calcium is a very important ion and is involved in:
-cell homeostasis
-coagulation
-muscle contraction
-neuronal impulse transmission/membrane stabilization
-bone formation and skeletal strength
-secretion processes99% is found in bone and 1% in the plasma. Of the 1% that is in the plasma
-45% is free ionized calcium
-45% is bound to proteins, mainly Albumin
-10% is present as an anion complexReduced levels of IONIZED calcium give rise to features of hypocalcaemia , resulting in increased excitability of membranes. This results when the total calcium concentration goes below 2 mmol/L.
Features of mild to moderate hypocalcaemia are:
-paraesthesia (peri-oral, fingers)
-tetany
-spasm
-muscle cramps
-ECG changes (prolonged QT)
-Trousseau’s sign (inflation of tourniquet induces carpopedal spasm)
-Chvostek’s sign (tapping the facial nerve – cranial nerve VII – causes facial muscle twitch/spasm)Features of severe hypocalcaemia are:
-cardiogenic shock and congestive cardiac failure due to reduced myocardial contractility
respiratory distress due to bronchospasm, agitation, confusion, seizuresFeatures of hypercalcaemia (remember ‘bones, stones, groans and psychic moans’):
-Abdominal pain
-Vomiting
-Constipation
-Polyuria
-Polydipsia
-Depression
-Lethargy
-Anorexia
-Weight loss
-Hypertension
-Confusion
-Pyrexia
-Calcification in the cornea
-Renal stones
-Renal failure
-Decreased Q-T interval
-Cardiac shock/collapse -
This question is part of the following fields:
- Physiology And Biochemistry
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