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Question 1
Correct
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The prospects of setting up a health facility to help patients with ischaemic heart disease in a remote area are under consideration and you have been asked to look into it. What's the crucial factor in finding out the amount of resources needed to go ahead with the idea?
Your Answer: Prevalence
Explanation:Both incidence and prevalence are indicators of the disease frequency. While incidence tells us about the number of cases reported per population in a provided time period, prevalence is the factor you should be vigilant about as it tells us about the total number of cases that have been reported in a population at a particular point of time.
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This question is part of the following fields:
- Statistical Methods
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Question 2
Incorrect
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Volunteers are being recruited for a new clinical trial of a novel drug treatment for Ulcerative colitis. The proposed study will enrol about 2000 people with ulcerative colitis. Testing will be performed to assess any reduction in disease severity with the new drug as compared to the current treatment available in the industry. Which phase of clinical trial will this be?
Your Answer: Phase 4
Correct Answer: Phase 3
Explanation:This clinical trial consists over 1000 patients being evaluated for the response to a new treatment against a currently licensed treatment for ulcerative colitis. Therefore, it is comparing its efficacy to an established therapeutic or control in a larger population of volunteers. These are the characteristics of a phase III clinical trial.
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This question is part of the following fields:
- Statistical Methods
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Question 3
Correct
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A 72-year-old man complains of severe, central abdominal pain that radiates to the back. He has a past medical history of an abdominal aortic aneurysm. A focused abdominal ultrasonography test (FAST) is performed, revealing diffuse dilatation of the abdominal aorta. The most prominent dilatation is at the bifurcation site of abdominal aorta into the iliac arteries. What vertebra level corresponds to the site of the most prominent dilatation as evident on the FAST scan?
Your Answer: L4
Explanation:The important landmarks of vessels arising from the abdominal aorta at different levels of vertebrae are:
T12 – Coeliac trunk
L1 – Left renal artery
L2 – Testicular or ovarian arteries
L3 – Inferior mesenteric artery
L4 – Bifurcation of the abdominal aorta.
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This question is part of the following fields:
- Anatomy
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Question 4
Correct
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In the United Kingdom, a new breast cancer screening test is being conducted compared to the conventional use of mammography. This test predicts that if the breast cancer is diagnosed at an earlier stage, it could improve the survival rate but the overall results remains constant. This is an example of what kind of bias?
Your Answer: Lead time bias
Explanation:Recall bias introduced when participants in a study are systematically more or less likely to recall and relate information on exposure depending on their outcome status.
In procedure bias, the researcher decides assignment of a treatment versus control and assigns particular patients to one group or the other non-randomly. This is unlikely to have occurred in this case, although it is not mentioned specifically.
Self Selection or volunteer bias occur when those subjects are selected to participate in the study who are not the representative of the entire target population. those subjects may be from high socio-economic status and practice those activities or lifestyle that improves their health.
Lead-time bias occurs when a disease is detected by a screening test at an earlier time point rather than it would have been diagnosed by its clinical appearance. In this bias, earlier detection improves the survival time in the intervention group.
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This question is part of the following fields:
- Statistical Methods
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Question 5
Correct
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A 89-year old male has hypertension, with a blood pressure of 170/68 mmHg and has been admitted to the hospital. He is on no regular medications. His large pulse pressure can be accounted for by which of the following?
Your Answer: Reduced aortic compliance
Explanation: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 = 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 -
This question is part of the following fields:
- Physiology And Biochemistry
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Question 6
Correct
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A new volatile anaesthetic agent has been approved for use in clinical testing. It's a non-irritating, sweet-smelling substance. It has a molecular weight of 170, a 0.6 blood:gas partition coefficient, and a 180 oil:gas partition coefficient. An oxidative pathway converts 2% of the substance to trifluoroacetic acid. Which of the following statements best describes this agent's pharmacological profile?
Your Answer: It has a lower molecular weight than isoflurane
Explanation:Because enflurane is much less soluble in blood and has a blood: gas partition coefficient of 1.8, both wash-in and wash-out should be faster.
Sevoflurane’s sweet-smelling, non-irritant nature, combined with a low blood: gas partition coefficient, would result in similar offset and onset characteristics.
Isoflurane and enflurane have a molecular weight of 184.
The oil: gas partition coefficient on a volatile agent is a measure of lipid solubility, potency, and thus MAC. Halothane has an oil: gas partition coefficient of 220 and a MAC of 0.74. One would expect the MAC to be higher with an oil gas partition coefficient of 180 (less lipid soluble).
The conversion of halothane (20%) to trifluoroacetic acid via oxidative metabolism has been linked to the development of hepatitis.
P450 2E1 converts sevoflurane to hexafluoroisopropanol, which results in the release of inorganic fluoride ions. It’s the only fluorinated volatile anaesthetic that doesn’t break down into trifluoracetic acid.
Desflurane is likely to cause airway irritation, which can lead to coughing, apnoea, and laryngospasm, despite its low blood:gas partition coefficient (0.42).
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This question is part of the following fields:
- Pharmacology
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Question 7
Correct
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Out of the following, which is NOT a part of the contents of the porta hepatis?
Your Answer: Cystic duct
Explanation:The porta hepatis is a fissure in the inferior surface of the liver. All the neurovascular structures that enter and leave the porta hepatis are:
1. hepatic portal vein
2. hepatic artery
3. hepatic ducts
4. hepatic nerve plexus (It contains the sympathetic branch to the liver and gallbladder and the parasympathetic, hepatic branch of the vagus nerve.)These structures supply and drain the liver. Only the hepatic vein is not part of the porta hepatis.
The porta hepatis is also surrounded by lymph nodes, that may enlarge to produce obstructive jaundice.
These structures divide immediately after or within the porta hepatis to supply the functional left and right lobes of the liver.The cystic duct lies outside the porta hepatis and is an important landmark in laparoscopic cholecystectomy.
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This question is part of the following fields:
- Anatomy
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Question 8
Correct
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A 27-year-old woman arrives at the emergency room after intentionally ingesting 2 g of amitriptyline. A Glasgow coma score of 6 was discovered, as well as a pulse rate of 140 beats per minute and a blood pressure of 80/50 mmHg. Which of the following ECG changes is most likely to indicate the onset of life-threatening arrhythmias?
Your Answer: Prolongation of the QRS complex
Explanation:Arrhythmias and/or hypotension are the most common causes of death from tricyclic antidepressant (TCA) overdose.
The quinidine-like actions of tricyclic antidepressants on cardiac tissues are primarily responsible for their toxicity. Conduction through the His-Purkinje system and the myocardium slows as phase 0 depolarisation of the action potential slows. QRS prolongation and atrioventricular block are caused by slowed impulse conduction, which also contributes to ventricular arrhythmias and hypotension.
Arrhythmias can also be caused by abnormal repolarization, impaired automaticity, cholinergic blockade, and inhibition of neuronal catecholamine uptake, among other things.
Acidaemia, hypotension, and hyperthermia can all exacerbate toxicity.
The anticholinergic effects of tricyclic antidepressants, as well as the blockade of neuronal catecholamine reuptake, cause sinus tachycardia. Sinus tachycardia is usually well tolerated and does not require treatment. It can be difficult to tell the difference between sinus tachycardia and ventricular tachycardia with QRS prolongation.
A QRS duration of more than 100 milliseconds indicates a higher risk of arrhythmia and should be treated with systemic sodium bicarbonate.
The tricyclic is dissociated from myocardial sodium channels by serum alkalinization, and the extracellular sodium load improves sodium channel function.
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This question is part of the following fields:
- Clinical Measurement
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Question 9
Correct
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Which of the following statements is true regarding alfentanil?
Your Answer: Is less lipid soluble than fentanyl
Explanation:Alfentanil is less lipid-soluble than fentanyl and thus is less permeable to the membrane making it less potent.
Alfentanil is a phenylpiperidine opioid analgesic with rapid onset and shorter duration of action.
Alfentanil has less volume of distribution due to its high plasma protein binding (92%)
It can cause respiratory depression and can cause sedation
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This question is part of the following fields:
- Pharmacology
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Question 10
Correct
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Which of the following statements is true regarding oxygen?
Your Answer: Forms molecules containing either two or three atoms
Explanation:Oxygen is formed by a molecule of oxygen and two molecules of hydrogen with a molecular formula of H2O
The critical temperature is defined as a temperature above which the substance cannot be liquefied, no matter how much pressure is applied.
Water has a critical temperature of -118.6oC. So, it cannot be liquified at room temperature.Medical oxygen cylinder is stored in a cylinder with a white shoulder and black body. Meanwhile, medial air is stored in cylinders with a white and black shoulder and a French grey body.
The partial pressure of air at a high altitude is less but the relative concentration remains constant.
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This question is part of the following fields:
- Basic Physics
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Question 11
Incorrect
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The right coronary artery supplies blood to all the following, except which?
Your Answer: The sino atrial node
Correct Answer: The circumflex artery
Explanation:The right coronary artery supplies the right ventricle, the right atrium, the sinoatrial (SA) node and the atrioventricular (AV) node.
The circumflex artery originates from the left coronary artery and is supplied by it.
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This question is part of the following fields:
- Anatomy
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Question 12
Correct
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The cardiac tissue type that that has the highest conduction velocity is:
Your Answer: Purkinje fibres
Explanation:Potassium maintains the resting potential of cardiac myocytes, with depolarization triggered by a rapid influx of sodium ions, and repolarization due to efflux of potassium. A slow influx of calcium is responsible for the longer duration of a cardiac action potential compared with skeletal muscle.
The cardiac action potential has several phases which have different mechanisms of action as seen below:
Phase 0: Rapid depolarisation – caused by a rapid sodium influx.
These channels automatically deactivate after a few ms.Phase 1: caused by early repolarisation and an efflux of potassium.
Phase 2: Plateau – caused by a slow influx of calcium.
Phase 3 – Final repolarisation – caused by an efflux of potassium.
Phase 4 – Restoration of ionic concentrations – The resting potential is restored by Na+/K+ATPase.
There is slow entry of Na+into the cell which decreases the potential difference until the threshold potential is reached. This then triggers a new action potentialOf note, cardiac muscle remains contracted 10-15 times longer than skeletal muscle.
Different sites have different conduction velocities:
1. Atrial conduction – Spreads along ordinary atrial myocardial fibres at 1 m/sec2. AV node conduction – 0.05 m/sec
3. Ventricular conduction – Purkinje fibres are of large diameter and achieve velocities of 2-4 m/sec, the fastest conduction in the heart. This allows a rapid and coordinated contraction of the ventricles
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This question is part of the following fields:
- Physiology And Biochemistry
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Question 13
Correct
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A 30-year-old man has been diagnosed with a direct inguinal hernia. A direct inguinal hernia passes through Hesselbach's triangle. What forms the medial edge of this triangle?
Your Answer: Rectus abdominis muscle
Explanation:The inguinal triangle of Hesselbach’s is an important clinical landmark on the posterior wall of the inguinal canal. It has the following relations:
Inferiorly – medial third of the inguinal ligament
Medially – lower lateral border of the rectus abdominis
Laterally – inferior epigastric vesselsDirect inguinal hernia is when the bowel bulges directly through the abdominal wall. These hernias usually protrude through Hesselbach’s triangle.
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This question is part of the following fields:
- Anatomy
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Question 14
Correct
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An 80-year-old presents to the emergency department with symptoms raising suspicion of mesenteric ischemia. To diagnose the condition, an angiogram is performed. The radiologist needs to cannulate the coeliac axis from the aorta for the angiogram. What vertebral level does the coeliac axis originate from the aorta?
Your Answer: T12
Explanation:Mesenteric ischemia is ischemia of the blood vessels of the intestines. It can be life-threatening especially if the small intestine is involved.
A critical factor for survival of acute mesenteric ischemia is early diagnosis and intervention. Angiography uses X-ray and contrast dye to image arteries and identify the severity of ischemia or obstruction.
The celiac axis is the first branch of the abdominal aorta and supplies the entire foregut (mouth to the major duodenal papilla). It arises at the level of vertebra T12. It has three major branches:
1. Left gastric
2. Common hepatic
3. Splenic arteriesThere are some important landmarks of vessels at different levels of vertebrae that need to be memorized.
T12 – Coeliac trunk
L1 – Left renal artery
L2 – Testicular or ovarian arteries
L3 – Inferior mesenteric artery
L4 – Bifurcation of the abdominal aorta.
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This question is part of the following fields:
- Anatomy
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Question 15
Correct
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A 70-year old male has diverticular disease and is undergoing a sigmoid colectomy. His risk of developing a post operative would infection can be minimized by which of the following interventions?
Your Answer: Administration of single dose of broad spectrum antibiotics prior to the procedure
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 16
Incorrect
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The following statements are about the cervical plexus. Which one is true?
Your Answer: The superficial branches pierce the deep fascia at the middle of the anterior border of the sternocleidomastoid muscle
Correct Answer: Recurrent laryngeal nerve block is a complication of a cervical plexus block
Explanation:The cervical plexus is a complex network of nerves within the head and neck region, providing nerve innervation to regions within the head, neck and trunk.
It is comprised of nerves arising from the anterior primary rami of the C1-C4 nerve roots.
The cervical plexus gives off superficial and deep branches. The superficial branches penetrate through the deep fascia at the centre point of the posterior border of the sternocleidomastoid. It provides sensory innervation from the lower border of the mandible to the 2nd rib. The deep branches provide motor innervation to the neck and diaphragmatic muscles.
Cervical plexus block is surgically relevant as it is used to provide regional anaesthesia for procedures in the neck region. The anaesthesia should be injected into the centre point of the posterior border of the sternocleidomastoid. Complications arise when anaesthesia is instead injected into the wrong point, including into the vertebral artery, subarachnoid and epidural spaces, blockade of phrenic and recurrent laryngeal nerves, and the cervical sympathetic plexus.
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This question is part of the following fields:
- Pathophysiology
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Question 17
Correct
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An 82-year-old male has severe abdominal pain that is out of proportion to the examination. He is a known case of atrial fibrillation and diverticulitis. Suspecting mesenteric ischemia, he was thoroughly investigated, and a mesenteric angiography shows ischemia of the left colic flexure. Which artery gives off branches that supply this region directly?
Your Answer: Inferior mesenteric artery (IMA)
Explanation:Mesenteric ischemia is ischemia of the blood vessels of the intestines. It can be life-threatening, especially if the small intestine is involved.
The inferior mesenteric artery originates 3-4 cm above the bifurcation of the abdominal aorta.
The left colic artery branches off the inferior mesenteric artery to supply the following:
– distal 1/3 of the transverse colon
– descending colonAt approximately the left colic flexure (splenic flexure), a transition occurs in the blood supply of the GI tract. The SMA supplies the proximal part to the flexure, and the IMA supplies the part distal to the flexure. This is why the left colic flexure is a watershed area and is prone to ischemia exacerbated by atherosclerotic changes or hypotension. The dominant arterial supply of the splenic flexure is usually from the left colic artery, but it may also get collaterals from the left branch of the middle colic artery.
The AMA and PMA do not exist.
The splenic artery directly supplies the spleen and has branches that supply the stomach and the pancreas.
The proximal two-thirds of the transverse colon is supplied by the middle colic artery, a branch of the SMA. -
This question is part of the following fields:
- Anatomy
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Question 18
Incorrect
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A 60 year old non insulin dependent diabetic on metformin undergoes hip arthroscopy under general anaesthesia. Her preoperative blood glucose is 6.5mmol/L. Anaesthesia is induced with 200 mg propofol and 100 mcg fentanyl and maintained with sevoflurane and air/oxygen mixture. she is given 8 mg dexamethasone, 40 mg parecoxib, 1 g paracetamol and 500 mL Hartmann's solution Intraoperatively. The procedure took thirty minutes and her blood glucose in recovery is 14 mmol/L. What is the most likely cause for her rise in blood sugar?
Your Answer: Fentanyl
Correct Answer: Stress response
Explanation:A significant early feature of the metabolic response to trauma and surgery is hyperglycaemia. It is due to an increased glucose production and decreased glucose utilisation bought on by neuroendocrine stimulation. Catecholamines, Growth hormone, ACTH and cortisol, and Glucagon are all increased.
There is also a decreased insulin sensitivity peripherally and an inhibition of insulin production from the beta cells of the pancreas. These changes lead to hyperglycaemia.
The stress response to endoscopic surgery will only be prevented with use of high dose opioids or central neuraxial block at anaesthesia.
To reduce the risk of inducing hyperchloremic acidosis, Ringer’s lactate/acetate or Hartmann’s solution is preferred to 0.9% sodium chloride as routine maintenance fluids.Though it has been suggested that administration of Hartmann’s solution to patients with type 2 diabetes leads to hyperglycaemia, one Litre of Hartmann’s solution would yield a maximum of 14.5 mmol of glucose. A rapid infusion of this volume would increase the plasma glucose by no more than 1 mmol/L..
Dexamethasone, a glucocorticoid, produces hyperglycaemia by stimulating gluconeogenesis . Glucocorticoids are agonists of intracellular glucocorticoid receptors. Their effects are mainly mediated via altered protein synthesis via gene transcription and so the onset of action is slow. The onset of action of dexamethasone is about one to four hours and therefore would NOT contribute to the hyperglycaemia in this patient in the time given.
0.9% Normal saline with or without adrenaline is the usual irrigation fluid. With this type of surgery, systemic absorption is unlikely to occur.
Fentanyl is not likely the primary cause of hyperglycaemia in this patient. In high doses (50 mcg/Kg) it has been shown to reduce the hyperglycaemic responses to surgery.
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This question is part of the following fields:
- Pathophysiology
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Question 19
Incorrect
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A 45-year old male who was involved in a road traffic accident has had to receive a large blood transfusion of whole blood which is two weeks old. Which of these best describes the oxygen carrying capacity of this blood?
Your Answer: It will more readily release oxygen in metabolically active tissues than fresh blood
Correct Answer: It will have an increased affinity for oxygen
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 20
Incorrect
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The cardiac muscle will primarily utilize which metabolic substrate to produce energy when at rest?
Your Answer: Lactate
Correct Answer: Fatty acids
Explanation:Approximately 70% of the heart’s ATP requirement is met by cardiac mitochondria through beta-oxidation of fatty acids at rest. The remaining 30% is supplied by glucose.
Amino acids and ketones, in the presence of ketoacidosis, may supply at most 10% of the ATP requirement. And, when in high levels, lactate may also contribute to the ATP requirement of the heart, particularly during moments of high muscular activity.
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This question is part of the following fields:
- Pathophysiology
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Question 21
Incorrect
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What is the order of the anatomical components of the tracheobronchial tree from proximal to distal?
Your Answer: Bronchioles, terminal bronchioles, respiratory bronchioles, alveolar sacs, alveolar ducts
Correct Answer: Bronchioles, terminal bronchioles, respiratory bronchioles, alveolar ducts, alveolar sacs
Explanation:The tracheobronchial tree is subdivided into the conducting and the respiratory zones.
The zones from proximal to distal are:
Trachea
Bronchi
Bronchioles
Terminal bronchioles
Respiratory bronchioles
Alveolar ducts
Alveolar sacsfrom the trachea to terminal bronchioles are the conducting zone while the respiratory zone is from the respiratory bronchioles to the alveola sacs.
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This question is part of the following fields:
- Anatomy
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Question 22
Incorrect
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It is safe to perform a central neuraxial block without an increased risk of developing a vertebral canal haematoma in?
Your Answer: A patient on subcutaneous low molecular weight heparin (LMWH) prophylaxis 6 hours after last dose
Correct Answer: A patient on clopidogrel 7 days after last dose
Explanation:The incidence of vertebral canal haematoma following neuraxial blockade was reported (third National Audit Project (NAP3)) as 0.85 per 100 000 (95% CI 0-1.8 per 100 000). The incidence following neuraxial blockade in coagulopathic patients is likely to be higher hence coagulopathy remains a relative contraindication for conducting a spinal or epidural. When indicate, risk and benefits are weighed, and it is only performed by experienced personnel in this case.
Acceptable time to perform a block after the last dose of rivaroxaban in a patient with a creatinine clearance of greater than 30mL/minute is 18 hours.
Acceptable time to perform a block after the last dose of subcutaneous LMWH as prophylaxis is 12 hours.
Acceptable time to perform a block after the last dose of subcutaneous UFH as prophylaxis is 4 hours.
Acceptable time to perform a block after the last dose of thrombolytic therapy (streptokinase or alteplase) is 10 days.
Clopidogrel should be stopped 7 days prior to surgery, particularly if a central neuraxial procedure is considered.
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This question is part of the following fields:
- Pathophysiology
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Question 23
Incorrect
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During exercise, muscle blood flow can increase by 20 to 50 times. Which mechanism is the most important for increased blood flow?
Your Answer: Beta-2 adrenoreceptor stimulation
Correct Answer: Local autoregulation
Explanation:Skeletal muscle blood flow is in the range of 1-4 ml/min per 100 g when at rest. Blood flow can reach 50-100 ml/min per 100 g during exercise. With maximal vasodilation, blood flow can increase 20 to 50 times.
The adrenal medulla releases catecholamines and increases neural sympathetic activity during exercise. Normally, alpha-1 and alpha-2 would cause vasoconstriction in the muscle groups being used, but vasodilatory metabolites override these effects, resulting in a so-called functional sympathectomy. Local hypoxia and hypercarbia, nitric oxide, K+ ions, adenosine, and lactate are some of the stimuli that cause vasodilation.
However, the splanchnic and cutaneous circulations, which supply inactive muscles, vasoconstrict.
Sympathetic cholinergic innervation of skeletal muscle arteries is found in some species (such as cats and dogs, but not humans). Vasodilation is induced by stimulating smooth muscle beta-2 adrenoreceptors, but at rest, the alpha-adrenoreceptor effects of adrenaline and noradrenaline predominate. During exercise, the skeletal muscle pump promotes venous emptying, but it does not necessarily increase blood flow.
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This question is part of the following fields:
- Physiology
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Question 24
Incorrect
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The typical fluid compartments in a normal 70kg male are:
Your Answer: intracellular>interstitial
Correct Answer: intracellular>extracellular
Explanation:Body fluid compartments in a 70kg male:
Total volume=42L (60% body weight)
Intracellular fluid compartment (ICF) =28L
Extracellular fluid compartment (ECF) = 14LECF comprises:
Intravascular fluid (plasma) = 3L
Extravascular fluid = 11LExtravascular fluids comprises:
Interstitial fluid = 10.5L
Transcellular fluid = 0.5L -
This question is part of the following fields:
- Physiology
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Question 25
Incorrect
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A 35-year-old male presents to GP presenting an area of erythema which was around a recent cut on his right forearm. He was prescribed a short course of antibiotics and after 5 days again presented with progressive fatigue, headaches, and fevers. On clinical examination: Oxygen saturation: 98% on room air, Respiratory rate: 22 per minute, Heart rate: 100 beats per minute, Blood pressure: 105/76 mmHg, Temperature: 38.2 degree Celsius. On physical examination, a dramatic increase in the area of erythema was noted. Blood culture was done in the patient and indicated the presence of bacterium containing beta-lactamase. Which of the following antibiotics was likely prescribed to the patient?
Your Answer: Minocycline
Correct Answer: Amoxicillin
Explanation:Ciprofloxacin belongs to the quinolone group of antibiotics, and doxycycline and minocycline are tetracyclines. So, they are not affected by beta-lactamase.
However, amoxicillin is a beta-lactam antibiotic and beta-lactamase cleaves the beta-lactam ring present in amoxicillin. This results in the breakdown of the antibiotic and thus the area of erythema dramatically increased.
Co-amoxiclav contains amoxicillin and clavulanic acid which protects amoxicillin from beta-lactamase. -
This question is part of the following fields:
- Pharmacology
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Question 26
Incorrect
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A 28-year-old man is admitted to the critical care unit. He has been diagnosed with adult respiratory distress syndrome and is being ventilated. His haemodynamic condition is improved using a pulmonary artery flotation. His readings are listed below: Haemoglobin concentration: 10 g/dL, Mixed venous oxygen saturation: 70%, Mixed venous oxygen tensions (PvO2): 50 mmHg. Estimate his mixed venous oxygen content (mL/100mL).
Your Answer: 10
Correct Answer: 9.5
Explanation:Mixed venous oxygen content (CvO2) is the oxygen concentration in 100mL of mixed venous blood taken from the pulmonary artery. It is usually 12-17 mL/dL (70-75%). It is represented mathematically as:
CvO2 = (1.34 x Hgb x SvO2 x 0.01) + (0.003 x PvO2)
Where,
1.34 = Huffner’s constant
Hgb = Haemoglobin level (g/dL)
SvO2 = % oxyhaemoglobin saturation of mixed venous blood
PvO2 = 0.0225 = mL of O2 dissolved per 100mL plasma per kPa, or 0.003 mL per mmHgTherefore,
CvO2 = (1.34 x 10 x 70 x 0.01) + (0.003 x 50)
CvO2 = 9.38 + 0.15 = 9.53 mL/100mL.
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This question is part of the following fields:
- Clinical Measurement
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Question 27
Correct
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Many of the processes we deal with in anaesthesia are exponential. What is the underlying mathematical principle of an exponential process?
Your Answer: The rate of change of x is dependent on the magnitude of x
Explanation:The magnitude of x determines the rate of change of x. First-order drug kinetics is a good example. Most drugs’ plasma levels are controlled by an exponential process. The rate of change in drug metabolism is proportional to the current plasma concentration (so-called non-linear kinetics).
A tear-away function is just one type of exponential relationship (y = ex), in which e is Euler’s number, x is the power, and e is the base. Natural logarithms rely on Euler’s number.
Euler’s number is a mathematical constant, not a mathematical principle. It’s referred to as an irrational number. This is a number that cannot be expressed as a simple fraction or a ratio.
A line or curve that acts as the limit of another line or curve is known as an asymptote. A washout exponential curve, for example, where the value y represents the plasma concentration of a drug in a single compartment model against time on the x axis. This descending curve approaches but never touches the x axis. This curve is asymptotic to the x axis, which is the curve’s asymptote. An asymptote isn’t just a characteristic of exponential curves.
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This question is part of the following fields:
- Basic Physics
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Question 28
Incorrect
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Following a physical assault, a 28-year-old man is admitted to the emergency room. A golf club has struck him in the head. There is a large haematoma on the scalp, as well as a bleeding wound. In response to painful stimuli, he opens his eyes and makes deliberate movements. Because of inappropriate responses, a history is impossible to construct, but words can be discerned. Which of the options below best describes his current Glasgow Coma Scale (GCS)?
Your Answer: E3V4M3=10
Correct Answer: E2V3M5=10
Explanation:The Glasgow Coma Scale (GCS) has been used in outcome models as a measure of physiological derangement and as a tool for assessing head trauma.
Eye opening (E):
4 Spontaneously
3 Responds to voice
2 Responds to painful stimulus
1 No response.Best verbal response (V):
5 Orientated, converses normally
4 Confused, disoriented conversation, but able to answer basic questions
3 Inappropriate responses, words discernible
2 Incomprehensible speech
1 Makes no sounds.Best motor response (M):
6 Obeys commands for movement
5 Purposeful movement to painful stimulus
4 Withdraws from pain
3 Abnormal (spastic) flexor response to painful stimuli, decorticate posture
2 Extensor response to painful stimuli, decerebrate posture
1 No response.In this case, GCS = 2+3+5 = 10.
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This question is part of the following fields:
- Pathophysiology
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Question 29
Incorrect
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Regarding thyroid hormones, one of the following is true.
Your Answer: D-thyroxine is more active than L-thyroxine
Correct Answer: Thyroid binding globulin (TBG) is increased in pregnancy
Explanation:T3 is produced by peripheral de-iodination of T4. It is more active than T4.
TBG, like most binding proteins, is increased in pregnancy. Because of this, measurement of free thyroid hormone concentration is more important than total.
T4 and T3 concentrations are decreased in Illness and starvation.
L-T4 that is the active molecule while D-T4 is inactive.
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This question is part of the following fields:
- Pathophysiology
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Question 30
Incorrect
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Standard error of the mean can be defined as:
Your Answer: Number of patients / square root (standard deviation)
Correct Answer: Standard deviation / square root (number of patients)
Explanation:The standard error of the mean (SEM) is a measure of the spread expected for the mean of the observations – i.e. how ‘accurate’ the calculated sample mean is from the true population mean. The relationship between the standard error of the mean and the standard deviation is such that, for a given sample size, the standard error of the mean equals the standard deviation divided by the square root of the sample size.
SEM = SD / square root (n)
where SD = standard deviation and n = sample size
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This question is part of the following fields:
- Statistical Methods
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Question 31
Correct
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The mandibular division of the trigeminal nerve passes through which anatomic structure?
Your Answer: Foramen ovale
Explanation:The mandibular branch of the trigeminal nerve passes through the foramen ovale. Other structures that pass through this foramen are the accessory meningeal artery, and occasionally, the lesser petrosal nerve.
These are the structures that pass through the other openings in the cranial fossa:
Foramen rotundum – Maxillary branch of the trigeminal nerve
Foramen lacerum – Greater petrosal nerve, traversed by the internal carotid artery
Superior orbital fissure – Oculomotor nerve; trochlear nerve; lacrimal, frontal and nasociliary branches of the ophthalmic branch of the trigeminal nerve; abducens nerve, superior ophthalmic vein
Stylomastoid foramen – facial nerve.
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This question is part of the following fields:
- Anatomy
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Question 32
Incorrect
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A 27-year-old woman takes part in a study looking into the effects of different dietary substrates on metabolism. She receives a 24-hour ethyl alcohol infusion. A constant volume, closed system respirometer is used to measure CO2 production and consumption. The production of carbon dioxide is found to be 200 mL/minute. Which of the following values most closely resembles her anticipated O2 consumption at the conclusion of the trial?
Your Answer: 200 mL/minute
Correct Answer: 300 mL/minute
Explanation:The respiratory quotient (RQ) is the ratio of CO2 produced by the body to O2 consumed in a given amount of time.
CO2 produced / O2 consumed = RQ
CO2 is produced at a rate of 200 mL per minute, while O2 is consumed at a rate of 250 mL per minute. An RQ of around 0.8 is typical for a mixed diet.
The RQ will change depending on the energy substrates consumed in the diet. Granulated sugar is a refined carbohydrate that contains 99.999 percent carbohydrate and no lipids, proteins, minerals, or vitamins.
Glucose and other hexose sugars (glucose and other hexose sugars):
RQ=1Fats:
RQ = 0.7Proteins:
Approximately 0.9 RQEthyl alcohol is a type of alcohol.
200/300 = 0.67 RQ
For complete oxidation, lipids and alcohol require more oxygen than carbohydrates.
When carbohydrate is converted to fat, the RQ can rise above 1.0. Fat deposition and weight gain are likely to occur in these circumstances.
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This question is part of the following fields:
- Physiology
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Question 33
Incorrect
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With respect to the peripheral nerve stimulators, which one is used to perform nerve blocking?
Your Answer: Stimulation in the mid-inguinal line causes plantar flexion
Correct Answer: Using an insulated needle improves the success rate for the block
Explanation:The nerve stimulators deliver a stimulus lasting for 1-2 milliseconds (not second) to perform nerve blockage.
There are just 2 leads (not 3); one for the skin and other for the needle.
Prior to the administration of the local anaesthesia, a current of 0.25 – 0.5 mA (not 1-2mA) at the frequency of 1-2 Hz is preferred.
If the needle tip is close to the nerve, muscular contraction could be possible at the lowest possible current.
Insulated needles have improved the block success rate, as the current is only conducting through needle tip.
Stimulus to the femoral nerve which is placed in the mid lingual line causes withdrawer of the quadriceps and knee extension, that’s the dancing patella ( not plantar flexion).
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This question is part of the following fields:
- Anaesthesia Related Apparatus
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Question 34
Incorrect
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All of the following statements are false regarding tetracyclines except:
Your Answer: Inhibit transpeptidation
Correct Answer: The simultaneous administration of aluminium hydroxide impedes its absorption
Explanation:Tetracyclines inhibit protein synthesis through reversible binding to bacterial 30s ribosomal subunits (not 50s) which prevent binding of new incoming amino acids (aminoacyl-tRNA) and thus interfere with peptide growth.
They penetrate macrophages and are thus a drug of choice for treating infections due to intracellular organisms.
Tetracycline does not inhibit transpeptidation. Meanwhile, it is chloramphenicol which is responsible for inhibiting transpeptidation.
Tetracycline can get deposited in growing bone and teeth due to its calcium-binding effect and thus causes dental discoloration and dental hypoplasia. Due to this reason, they should be avoided in pregnant or lactating mothers.
Simultaneous administration of aluminium hydroxide can impede the absorption of tetracyclines.
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This question is part of the following fields:
- Pharmacology
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Question 35
Incorrect
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In a normal healthy adult breathing 100 percent oxygen, which of the following is the most likely cause of an alveolar-arterial (A-a) oxygen difference of 30 kPa?
Your Answer: Hypoventilation
Correct Answer: Atelectasis
Explanation:The ‘ideal’ alveolar PO2 minus arterial PO2 is the alveolar-arterial (A-a) oxygen difference.
The ‘ideal’ alveolar PO2 is derived from the alveolar air equation and is the PO2 that the lung would have if there was no ventilation-perfusion (V/Q) inequality and it was exchanging gas at the same respiratory exchange ratio as real lung.
The amount of oxygen in the blood is measured directly in the arteries.
The A-a oxygen difference (or gradient) is a useful measure of shunt and V/Q mismatch, and it is less than 2 kPa in normal adults breathing air (15 mmHg). Because the shunt component is not corrected, the A-a difference increases when breathing 100 percent oxygen, and it can be up to 15 kPa (115 mmHg).
An abnormally low or abnormally high V/Q ratio within the lung can cause an increased A-a difference, though the former is more common. Atelectasis, which results in a low V/Q ratio, is the most likely cause of an A-a difference in a healthy adult breathing 100 percent oxygen.
Hypoventilation may cause an increase in alveolar (and thus arterial) CO2, lowering alveolar PO2 according to the alveolar air equation.
The alveolar PO2 is also reduced at high altitude.
Healthy people are unlikely to have a right-to-left shunt or an oxygen transport diffusion defect.
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This question is part of the following fields:
- Physiology
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Question 36
Incorrect
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Which of the following is the smallest value of pressure?
Your Answer: 1,520 mmHg
Correct Answer: 14.69 psi
Explanation:The SI unit of pressure is the pascal (Pa) and it is equal to one newton (N) per square meter (m2) or N/m2.
1 atmosphere (atm) is the equivalent of:
101325 Pa760 mmHg
1.01325 bar
1033.23 cmH2O.
14.69 pounds per square inch (psi)
1013.25 millibar (mbar) or hectopascals (hPa), and14.69 psi is equal to one atmosphere. The other values are equal to two atmospheres of pressure.
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This question is part of the following fields:
- Basic Physics
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Question 37
Incorrect
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Which of the following statement is correct regarding the difference between dabigatran and other anticoagulants?
Your Answer: Reduced platelet aggregation
Correct Answer: Competitive thrombin inhibitor blocking both free and bound thrombin
Explanation:Dabigatran template is a prodrug and its active metabolite is a direct thrombin inhibitor. It is a synthetic, reversible, non-peptide thrombin inhibitor. This inhibition of thrombin results in a decrease of fibrin and reduces platelet aggregation.
Drugs like warfarin act by inhibiting the activation of vitamin K-dependent clotting factors. These factors are synthesized by the liver and activated by gamma-carboxylation of glutamate residues with the help of vitamin K. Hydroquinone form of vitamin K is converted to epoxide form in this reaction and regeneration of hydroquinone form by enzyme vitamin K epoxide reductase (VKOR) is required for this activity. Oral anticoagulants prevent this regeneration by inhibiting VKOR, thus vitamin K-dependent factors are not activated. These factors include clotting factors II, VII, IX, and X as well as anti-clotting proteins, protein C and protein S.
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This question is part of the following fields:
- Pharmacology
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Question 38
Incorrect
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An otherwise fit 7-year-old boy for an elective tonsillectomy is seen holding a bottle of sugared orange squash at anaesthetic assessment . He appears to have consumed 120 mL of the bottle's contents. What is the minimal safe fasting time prior to proceeding with a general anaesthetic in this patient?
Your Answer: 12 hours
Correct Answer: 1 hour
Explanation:The incidence of Pulmonary aspiration in children is about 0.07%€�0.1%.
The Association of Paediatric Anaesthetists of Great Britain and Ireland, The European Society of Paediatric Anaesthetists and L’Association Des Anesthésistes€�Réanimateurs Pédiatriques d’Expression Française produced a consensus statement in April 2018 with revised starvation times in children prior to elective surgery.
The preoperative fasting for elective procedures for children aged 0-16 years of age are:
Solid food/formula milk – 6 hours
Breast milk – 4 hours
Clear fluid – 1 hourA liberal clear fluid fasting regime does not affect the incidence of pulmonary aspiration in children as long as there are no specific contraindications (e.g. gastro-oesophageal reflux, cerebral palsy). Prolonged periods of fasting in children are associated with increase thirst and irritability and can lead to other adverse physiological and metabolic effects.
Clear fluids are defined as water, clear (nonopaque) fruit juice or squash/cordial, ready diluted drinks, and non-fizzy sports drinks.
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This question is part of the following fields:
- Pathophysiology
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Question 39
Incorrect
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Which of the following is a feature of a central venous pressure waveform?
Your Answer: A y descent due to atrial relaxation
Correct Answer: An a wave due to atrial contraction
Explanation:The central venous pressure (CVP) waveform depicts changes of pressure within the right atrium. Different parts of the waveform are:
A wave: which represents atrial contraction. It is synonymous with the P wave seen during an ECG. It is often eliminated in the presence of atrial fibrillation, and increased tricuspid stenosis, pulmonary stenosis and pulmonary hypertension.
C wave: which represents right ventricle contraction at the point where the tricuspid valve bulges into the right atrium. It is synonymous with the QRS complex seen on ECG.
X descent: which represents relaxation of the atrial diastole and a decrease in atrial pressure, due to the downward movement of the right ventricle as it contracts. It is synonymous with the point before the T wave on ECG.
V wave: which represents an increase in atrial pressure just before the opening of the tricuspid valve. It is synonymous with the point after the T wave on ECG. It is increased in the background of a tricuspid regurgitation.
Y descent: which represents the emptying of the atrium as the tricuspid valve opens to allow for blood flow into the ventricle in early diastole.
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This question is part of the following fields:
- Pathophysiology
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Question 40
Incorrect
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Which of the following is true when testing for statistical significance?
Your Answer:
Correct 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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