Applied and Basic sciences Flashcards
(99 cards)
1
Q
Platelets
A
Platelets are membrane-encapsulated fragments of megakaryoctes.
Although platelets have no nucleus, they are metabolically active and are able to express membrane receptors and release stored substances when triggered. They contain adenosine diphosphate and serotonin.
However, because they have no nucleus they are unable to produce new proteins and therefore aspirin and other drugs affect function for the remainder of the platelet lifespan. Platelet lifespan is approximately 9-10 days in normal individuals.
Platelets are capable of producing nitric oxide, prostaglandins and thromboxane, but not the vasodilator prostacyclin.
2
Q
Predisposing factors for the development of keloid scars include which of the following?
Male sex Patients of Afro-Caribbean origin with dark complexion Secondary wound closure Steroid therapy Use of local bupivacaine
A
Keloid scars are characterised by smooth hard nodules caused by excessive collagen production. Keloid scarring is much commoner in people of Afro-Caribbean origin. They also tend to affect young adults a lot more.
Keloid scarring may occur spontaneously but is associated with skin trauma, infection, and surgery.
There is no evidence to suggest that keloid scarring is associated with steroid therapy. However, if keloid scarring is treated with surgical removal then it must be followed by steroid injection or superficial radiotherapy or it may make the problem worse.
There is no evidence to suggest that keloid scarring is associated with wound healing by secondary intention. There is some evidence to suggest that primary wound closure is a risk factor.
Local anaesthetics are not associated with keloid scarring. They can be used in surgical removal of the scar.
Other methods of treatment include triamcinolone injection and compression with silica gels.
3
Q
Which one of the following gases can be measured by infrared analysers?
A
Gases with molecules that contain at least two dissimilar atoms absorb radiation in the infrared region of the electromagnetic spectrum. Therefore, carbon dioxide, nitrous oxide and all the halogenated volatile anaesthetic agents can be measured using infrared absorption analysers.
Oxygen, nitrogen, helium and the inert (or noble) gases do not absorb infrared light and cannot be measured using this technology.
Oxygen is measured using the paramagnetic, galvanic or polarographic method.
4
Q
Oncogenes and tumour suppressor genes
Which genetic abnormality is most strongly associated with BCR-ABL
A
CML
BCR-ABL is a gene implicated in chronic myeloid leukaemia. The Philadelphia chromosome found in this malignancy results from a reciprocal translocation between chromosomes 9 and 22. The breakpoint on chromosome 22 is at the BCR gene and, on chromosome 9, the ABL gene.
5
Q
Oncogenes and tumour suppressor genes
Which genetic abnormality is most strongly associated with B-RAF
A
B-RAF is an oncogene associated with a range of cancers. These include
malignant melanoma
Lymphomas
Non-small cell carcinoma
Adenocarcinoma of the lung.
6
Q
Oncogenes and tumour suppressor genes
Which genetic abnormality is most strongly associated with BRCA
A
Breast cancer
BRCAs 1 and 2 are tumour suppressor genes strongly associated with inherited forms of breast cancer. Women with an abnormal BRCA gene have an 85% chance of developing breast cancer before the age of 70. There is also a significantly increased risk of developing ovarian cancer in these patients.
7
Q
Which of the following is true regarding prostaglandins?
Cause uterine dilatation
Decrease blood flow to the kidneys
Increase gastric acid secretion
Lead to inflammatory responses
A
Lead to inflammatory responses
Prostaglandins act as chemical messengers at the site where they are synthesised. They are thus different from hormones, which can be transported in the blood and can act in distant sites in the body.
Prostaglandins have a variety of physiological effects including:
- Activate the inflammatory response at the site of tissue injury, leading to pain, swelling, redness and increase in temperature
- Haemostatic properties, such as when there is blood vessel damage (thromboxane stimulates vasoconstriction and activation of platelets)
- Stimulate uterine contractions and thus are effective in inducing labour
- Inhibit acid synthesis (including gastric acid) and increase secretion of protective mucus within the GI tract
- Increase blood flow in kidneys
- Constriction of bronchi, thus exacerbating bronchial asthma.
8
Q
In the presence of inflammation, which of the following is decreased?
Caeruloplasmin Complement proteins Fibrinogen Platelets Sweating
A
Inflammation induces high systemic levels of acute-phase proteins.
These proteins include C-reactive protein and vasopressin, which cause a range of systemic effects including;
Fever Increased blood pressure Decreased sweating and Loss of appetite. Thrombocythaemia occurs with chronic inflammation, for example, in rheumatoid arthritis.
Ferritin is an acute-phase reactant and serum levels rise in inflammation.
Caeruloplasmin is a copper carrying protein that is also an acute phase reactant.
Fibrinogen is a clotting factor and synthesis is increased by the liver in inflammation along with other acute phase proteins.
Complement proteins such as C3a and C5a have multiple roles in inflammation (chemotaxis, bacterial pore lysis) and serum levels rise accordingly.
9
Q
Which of the following is true regarding Pseudomonas aeruginosa?
Can cause osteomyelitis
Is a Gram positive bacterium
Is an uncommon cause of contact lens acquired infection
Is sensitive to chloramphenicol
Is usually resistant to ciprofloxacin
A
Osteomyelitis
Infection rates can be reduced by wearing the contact lens for 10 hours or less.
It is a Gram negative aerobic bacillus.
The most common organisms that cause osteomyelitis are Staphylococcus, Haemophilus influenzae, and Salmonella, although P. aeruginosa can cause osteomyelitis.
Chloramphenicol has good activity against Haemophilus influenzae but not P. Aeruginosa.
P. Aeruginosa is sensitive to quinolones which inhibit DNA topoisomerase
10
Q
Concerning which of the following must an aetiological factor satisfy the following before one can say that it is causally related to a disease?
Exposure to the factor may not necessarily precede the development of the disease
Elimination of the factor does not decreases the risk of the disease
The factor is found more frequently among the diseased than non-diseased
The factor is not found among persons without the disease
The factor is found in all cases with the disease
A
The factor is found more frequently among the diseased than non-diseased
Hill devised criteria for assessing causation and proposed that the cause must precede the effect.
Again, Hill’s criteria suggest that when assessing causation removing the factor of interest should reduce the risk of disease.
Hill suggested that there should be a dose-response relationship, that is, higher levels of the effect should lead to more severe disease or more rapid disease onset.
To illustrate this principle one can look at rheumatoid factor. It is found in people both with and without rheumatoid arthritis. Again, autoantibody tests illustrate this principle as they can be found in unaffected patients.
11
Q
Which of the following statements is true of wound infections?
Anaerobic organisms exert their lethal effects by producing endo- and exotoxins
MRSA wound infection is usually the result of wound contamination by the patient
Necrotising fasciitis is commoner in carriers of MRSA
Opportunistic organisms tend to affect young healthy adults
Streptococcus is the most common organism to infect the surgical wound
A
Anaerobic organisms exert their lethal effects by producing endo- and exotoxins
Staphylococci are aerobic, facultatively anaerobic, Gram positive cocci. They are the most common organism to infect the surgical wound as they are common skin commensals.
MRSA wound infection is hospital acquired and the risk of acquisition can be minimised by basic precautions such as hand washing before wound inspection. Sepsis and its sequelae such as acute respiratory distress syndrome illustrate this principle.
As part of sepsis toxins damage the endothelium of the lung capillaries and the accompanying inflammatory response results in oedematous changes and haemodynamic instability.
Surgical wounds become infected with opportunistic organisms because of the relatively immunocompromised state of the post-operative patient resulting in reduced microbial inhibitions.
Necrotising fasciitis is a deep-seated aggressive infection of subcutaneous tissue and skin. It is commonly caused by group A Streptococci and there is no evidence to suggest it is commoner in carriers of MRSA.
12
Q
Laparoscopy:
A 1 cm vertical incision was made below the umbilicus at the start of the procedure. Two stay sutures are placed in the fascia and the fascia divided. A blunt instrument was then inserted and a pneumoperitoneum was created.
A
This is Hassan’s cannula. The description given is that of an open technique (Hassan technique) of creating a pneumoperitoneum. The open technique avoids the relatively rare but potentially disastrous accidental perforation of an intra-abdominal structure during the insertion of a Veress needle (closed technique).
Gynaecologists are still keen on the Veress needle, thus providing general surgical registrars with valuable experience of iatrogenic abdominal injury.
13
Q
Laparoscopy:
During a laparoscopic cholecystectomy Calot’s triangle is dissected out using which instrument?
A
A number of instruments are available for dissecting structures laparoscopically. A Petalan’s forceps is usually favoured as it has a curved end and only the upper jaw moves. This provides more controlled dissection.
14
Q
Laparoscopy:
Once the cystic duct and artery are clearly identified they are ligated and divided close to the gallbladder.
A
Three clips are placed on the cystic duct and on the artery. The artery and duct are then divided between the two clips nearest the gallbladder.
15
Q
Antibiotic prophylaxis prior to operations
A
Antibiotic prophylaxis is used to prevent infection and is based on the degree of contamination involved in the surgical procedure.
Breast, thyroid and hernia repair operations, where there is minimal risk of wound contamination, are classed as clean surgery. Antibiotic prophylaxis is controversial in this group. Most surgeons choose no antibiotics at all or one single shot of broad spectrum antibiotic at induction.
Operations such as cholecystectomy, elective/interval appendicectomy or bowel resection, where the contamination of the wound can be contained/controlled, are classed as clean contaminated wounds and require broad spectrum antibiotics given at induction and every six hours intra-operatively if the surgery is prolonged. The use of post-operative antibiotics is debatable in these situations.
Emergency operations or those where the amount of contamination is difficult to contain or estimate (including traumatic wounds) are classed as contaminated and are shown to benefit from 72 hours of intravenous broad spectrum antibiotics. Uncomplicated, early appendicitis generally only requires anaerobic cover with induction.
Grossly contaminated wounds before the start of surgery are classed as dirty wounds and need therapeutic antibiotics as opposed to prophylaxis - the choice of antibiotic being empirical as determined by the source of contamination.
Certain special conditions need specific antibiotic prophylaxis, as otherwise they could result in severe infections anywhere in the body. These include immune compromised states (including splenectomy and steroid therapy).
As outlined in the NICE guidance on Prophylaxis against infective endocarditis (CG64), routine antibiotic prophylaxis is no longer recommended for dental procedures or routine surgery for patients with congenital or acquired heart disease.
16
Q
Intravenous broad spectrum antibiotics, including anaerobic cover, commencing in the operating theatre with the induction of anaesthesia.
A
Emergency sigmoid colectomy
17
Q
No antibiotic prophylaxis.
A
Dental procedure for patient with atrial septal defect
18
Q
Penicillin G
A
Splenectomy
19
Q
Intravenous metronidazole during the induction of anaesthesia.
A
Emergency appendicectomy
20
Q
A 45-year-old male with pyloric stenosis presents with profuse vomiting and abdominal pain. What else besides a hypokalaemia may be expected?
A
Metabolic alkalosis
Patients with pyloric stenosis develop hypochloraemic hypokalaemic alkalosis, as they lose chloride ions with hydrogen ions when they vomit.
21
Q
A 60-year-old man with villous adenoma presents with profuse diarrhoea.
A
Hypokalaemia
Villous adenoma is associated with profuse watery diarrhoea, which is typically associated with hypokalaemia.
22
Q
A 62-year-old man presents to the emergency department with a six hour history of severe pain and altered sensation in his left leg. On examination, the pulses are absent beyond the femoral artery, his foot is cold and sensation is reduced. He is in atrial fibrillation and duplex scan of the femoral artery reveals a blockage in the common femoral artery.
A
Femoral embolectomy
This patient has got an acute embolic event, possibly from the underlying atrial fibrillation. He is manifesting signs of severe vascular compromise which if left untreated would soon progress to critical ischaemia. The six cardinal signs of critical ischaemia are: pain, pallor, pulselessness, paralysis, paraesthesia and cold to touch (perishing with cold). In this patient, since there is no pulsation beyond the superficial femoral artery and the duplex scan reveals a blockage in the common femoral artery, the most appropriate procedure would be a femoral embolectomy which can be undertaken either under general or local anaesthesia.
23
Q
A 65-year-old man presents to the vascular outpatient clinic with a four month history of pain in his legs whilst walking. He claudicates at around 75-100 yards. He has no rest pain. He is fit and well apart from osteoarthritis in his knees. Angiogram reveals occlusion of the lower end of abdominal aorta including the bifurcation but patent femoral vessels.
A
Aorto=bifemoral bypass
This patient is suitable for an aorto-bifemoral bypass grafting since his blockage is limited to the aorta and the bifurcation but has patent femoral vessels. He is also medically fit to undergo this procedure. Aorto-bifemoral bypass grafting has the highest patency rate of any bypass procedures to the femoral vessels.
24
Q
An 89-year-old man presents to the vascular outpatient clinic with inability to walk beyond 20-30 yards and severe rest pain. On examination, his legs are manifesting evidence of impending critical ischaemia. He has a type I diabetes, is hypertensive and has severe ischaemic heart disease. Angiogram reveals complete occlusion of the aorta but patent femoral vessels bilaterally.
A
Axillo-bifemoral bypass graft
Since this patient is elderly, has serious underlying medical problems, and is manifesting signs of impending critical ischaemia, an axillo-bifemoral bypass graft would be the most appropriate procedure. This type of grafting should be considered in surgically/anaesthetically unfit patients who have or are manifesting early signs of critical ischaemia. This procedure is less traumatic and complicated than an aorto-bifemoral bypass for the simple reason that it does not involve a laparotomy or clamping the aorta. It is not an appropriate procedure in patients with intermittent claudication.
25
Which of the following is regarded as an Indication for tonsillectomy?
The indications for tonsillectomy are controversial. Undoubtedly, upper airway obstruction, particularly if associated with hypoxaemia or apnoea, is a clear indication.
In most cases, recurrent tonsillitis with pus requiring antibiotic therapy more than three times a year for three successive years would encourage the surgeon to remove the tonsils. This is particularly the case if there has been a previous abscess.
However, if there is no history of chronic tonsillitis, the chance of a recurrence of quinsy is only about 10%, so isolated incision and drainage with antibiotics is all that is required.
26
Which of the following is correct regarding pulse oximetry?
Pulse oximetry is a non-invasive method of assessing arterial oxygen saturation and heart rate.
Any cause of poor peripheral perfusion causes unreliable readings, including external compression by a blood pressure cuff.
Though there may be mechanical causes for poor pulse oximetry readings you should always look for a physiological cause first. For example, vasoconstriction is one of the first compensatory mechanisms employed by the body following blood loss.
In these situations it is often helpful to check pulse rate in comparison to the electrocardiogram (ECG).
Other causes of error include abnormal pigments such as bilirubin, methaemoglobin and carboxyhaemoglobin. Jaundice underestimates the actual oxygen saturation, whereas carbon monoxide poisoning overestimates the level of saturation.
When the partial pressure of oxygen is plotted against percentage saturation, a sigmoidal curve is produced. The middle range of the curve is therefore particularly important as small changes in partial pressure will cause large changes in saturation.
Certain factors may result in 'shifts' in the curve. The following cause a right shift in the curve:
```
reduced pH
increased temperature
partial pressure of carbon dioxide, and
2-3 diphosphoglycerates.
This means that haemoglobin gives up oxygen more easily to the tissues.
```
27
Which one of the following is unlikely to inhibit wound healing?
```
Excessive methionine in the diet
High doses of corticosteroids
Low temperatures
Malnutrition
Vitamin C (ascorbic acid) deficiency
```
Wound healing is delayed in
```
Zinc deficiency
Methionine deficiency
Vitamin C deficiency (scurvy)
Hypothermia
Diabetes
Malnutrition
Cushing's syndrome.
```
28
Alpha-ketoglutarate is a five carbon molecule
Krebs' cycle (tricarboxylic acid cycle or citric acid cycle) is a sequence of reactions in which acetyl coenzyme A (acetyl-CoA) is metabolised to carbon dioxide and hydrogen atoms.
The sequence of reactions is known collectively as oxidative phosphorylation, which only occurs in the mitochondria (not cytoplasm).
The cycle requires oxygen and does not function under anaerobic conditions. It is the common pathway for the oxidation of carbohydrate, fat and some amino acids, required for the formation of high energy phosphate bonds in adenosine triphosphate (ATP).
Pyruvate enters the mitochondria and is converted into acetyl-CoA, which represents the formation of a two carbon molecule from a three carbon molecule (with the loss of one CO2 and the formation of one NADH molecule). Acetyl-CoA is then condensed with the anion of a four carbon acid, oxaloacetate, to form citrate which is a six carbon molecule.
Citrate is subsequently converted into isocitrate, alpha-ketoglutarate, succinyl-CoA, succinate, fumarate, malate and finally oxaloacetate.
Alpha-ketoglutarate is the only five carbon molecule in the cycle.
29
Which of the following electrocardiogram (ECG) changes is associated with a suspected myocardial infarction?
The usual ECG changes following an acute myocardial infarction include S-T elevation greater than 1 mm (convex upwards, concave downwards) developing within the first few hours. Tall peaked T waves may also be seen in the acute stages.
Pathological Q waves (representing transmural infarction), a reduction in R wave height and deeply inverted T waves (in the leads facing the infarcted muscle) may develop over the next 72 hours.
The absence of Q waves implies partial-thickness infarction. A subendocardial MI is associated with flat S-T depression (not elevation) and T wave inversion in leads facing the infarction.
The S-T segment changes following a myocardial infarct usually resolve within days. The T wave changes often persist for weeks but may be permanent. The Q waves are usually, but not always permanent.
It is possible to diagnose an acute MI in the presence of right bundle branch block and also in left bundle branch block when using non-standard ECG criteria.
True posterior left ventricular infarction is characterised by tall R waves, S-T depression and peaked upright (not inverted) T waves in leads V1 and V2.
Right ventricular infarction does not produce a specific pattern in the standard 12 lead ECG, so the use of right-sided precordial leads (V4R - V6R) is required.
30
transcutaneous liver biopsy is considered for an 80-year-old female
Contraindications?
A haemoglobin concentration of 9.9 g/dl (NR 11.5-15.5)
A platelet count of 140 ×109 (NR 150-400)
Age
An INR of 1.5
Extra-hepatic biliary obstruction
Contraindications to liver biopsy include:
Bacterial cholangitis because of the risk of causing peritonitis or septic shock.
A platelet count below 80,000/mm3 (there is no absolute agreed lower level: 50,0003 may be acceptable. Platelet function is more important than absolute numbers (eg stop clopidogrel a week before)
A deranged INR above 1.5 (this value is debatable as 90% of bleeds occur in patients with an INR
31
Regarding prostate specific antigen (PSA), which of the following is correct?
Elevated concentrations are expected following digital rectal examination (DRE)
Is a serine protease
Is found only in the prostate
Is required for sperm motility
Mutations of the PSA gene are aetiological in the development of prostate cancer
PSA was thought to be specific for the prostate but we now realise that it is found in the peri-urethral glands, peri-anal glands and also in breast tumours.
Concentrations are elevated in benign prostatic hyperplasia, prostate cancer and following procedures such as biopsy.
Although there may be a small rise in PSA following digital rectal examination (DRE), elevated concentrations are not expected.
Gene mutations are not associated with prosate cancer - which is associated with oncogenes such as c-myc, etc.
Its role is in the liquefaction of seminal gel not in sperm motility.
A normal PSA does not exclude prostate cancer with studies showing a risk of 15% of prostate Ca in subjects with a PSA less than 4 ng/ml.
32
Barr body is caused by the presence of an inactive X chromosome
Barr body is only found in people who are phenotypically female
Cells containing YO chromosome are compatible with life
The Y chromosome is larger than the X chromosome
There are 23 pairs of autosomal chromosomes
During interphase chromosomes are too tenuous to be stained and seen by light microscopy. However, a dense, stainable structure, called a Barr body (after its discoverer) is seen in the interphase nuclei of female mammals. The Barr body is one of the X chromosomes. Its compact appearance reflects its inactivity.
People with XXY or XXXY karyotypes are males (because of their Y chromosome), and display the features of Klinefelter's syndrome. The phenotypic effects of the extra X chromosomes are mild because, just as in females, the extra Xs are inactivated and converted into Barr bodies.
No YO individuals have been identified, not even aborted fetuses. It has been suggested that there is something fundamental on the X chromosome that is needed for life.
The Y chromosome is smaller than the X chromosome.
There are 22 pairs of autosomes, and one pair of sex chromosomes.
33
```
Regarding Staphylococcus aureus
Is a Gram positive motile organism
Is arranged in chains
Is typically anaerobic
Produces a coagulase
Produces endotoxin
```
Staph aureus is a Gram positive, non-motile, aerobic coccus whose colonies are arranged in grape-like clusters.
Strains are responsible for food poisoning through the production of an enterotoxin and pathogenicity is also associated with coagulase positivity.
34
A 45-year-old female is noted to have a mean cell volume (MCV) of 102 fl (80-96) on full blood count.
Causes of a high MCV include folate or B12 deficiency (pernicious anaemia), alcoholism and hypothyroidism.
Blood loss, as in peptic ulceration or menorrhagia, is associated with iron deficiency and microcytosis.
35
By which of the following is HIV not reliably inactivated?
```
Chlorhexidine
Glutaraldehyde
Hypochlorites
The autoclave
The hot-air oven
```
Chlorhexidine is effective, but does not guarantee complete clearance of HIV.
36
Which factor does not affect the performance of a disinfectant?
```
Concentration of disinfectant
Number of organisms present
pH
Type of organisms
Water hardness
```
The concentration of disinfectant, as well as the type of organism, are also important factors.
Numbers of organisms - high numbers of organisms leads to clump formation. Organisms inside of the clump are shielded from the control method.
pH plays an important role in the performance of a disinfectant. Many organisms have an optimum pH at which they work best. Deviation from this optimum value results in loss of activity.
Water hardness was historically a problem for disinfectants dissolved in water. However, modern disinfectants are able to withstand water hardness.
Temperature is also an important factor: warm liquid disinfectants are more effective than colder ones, as increasing the temperature decreases surface tension whilst also increasing the rate of chemical reactions.
37
Which of the following statements concerning intravenous fluids is correct?
0.9% saline solution has a similar pH to plasma
Colloids generally have lower sodium concentrations than 0.9% saline
Hartmann's solution has a higher chloride concentration than 0.9% saline
Hydroxyethyl starch solutions interfere with blood cross-matching
Pruritis is associated with the use of hydroxyethyl starch solutions
Hartmann's solution contains
```
131 mmol per litre of sodium ions
111 mmol per litre of chloride ions
2 mmol per litre of calcium ions
5 mmol per litre of potassium ions
29 mmol per litre of lactate ions.
It therefore has a lower chloride concentration than 0.9% saline (154 mmol per litre of sodium and chloride ions).
```
0.9% saline has a pH of 5.5, whereas plasma pH is approximately 7.4.
Hydroxyethyl starch solutions do not interfere with blood cross-matching, unlike the dextrans, although rouleaux formation may occur.
Artificial colloids are suspensions of large molecules in 0.9% saline and so contain 154 mmol per litre of sodium (the same).
The hydroxyethyl starches are removed from the circulation by the reticuloendothelial system and are deposited in the skin.
Pruritis is therefore a relatively common and significant sequel of over-enthusiastic administration of starches.
38
Which of the following is true regarding penicillins?
Are bacteriostatic
Exert their actions by combining with a transpeptidase
Have a spectrum of action which is independent of the beta-lactam side chain
Have significant toxic effects on humans
May be activated by enzymes which are plasmid coded
Exert their actions by combining with a transpeptidase
Penicillins are generally bactericidal and exert their effect by combining with and inhibiting the transpeptidase enzyme which cross-links the peptidoglycans in the cell wall. This weakens the cell wall and allows the cell to lyse under the influence of an osmotic gradient.
The widespread resistance to penicillins is due to beta-lactamase enzymes which break the beta-lactam ring and inactivate the drug.
The beta-lactamase enzyme is often encoded in the bacterial plasmid. The plasmid is bacterial DNA (separate from the main chromosome) that can be translocated from bacterium to bacterium and it is for this reason that resistance may be also transferred.
Although the penicillins have similar spectra of action, their specific spectra may be changed by altering the beta-lactam side chain.
They do not have significant toxic effects on humans, but allergy is common.
39
Which one of the following statements regarding intravenous fluids is correct?
5% dextrose has a pH of 6.0
Haemaccel causes histamine release
Hartmann's solution contains 154 mmol/l of sodium
Normal saline contains 150 mmol/l of both potassium and chloride
The average particle size in hydroxyethyl starch is 300,000 kDa
Haemaccel causes histamine release
All dextrose containing crystalloid solutions has a pH of 4.0 (not 6.0).
Haemaccel does cause histamine release and at 0.15% has a low incidence of allergic reactions.
Hartmann's solution (compound sodium lactate or Ringer's lactate) contains
```
131 mmol/l of sodium
111 mmol/l of chloride
5 mmol/l of potassium
2 mmol/l of calcium
29 mmol/l of lactate.
Normal saline or 0.9% sodium chloride contains 154 mmol/l of both sodium and chloride in water, and it does not contain potassium.
```
At 70,000 kDa hydroxyethyl starch has an average particle size similar to albumin.
40
Which of the following is true regarding the insertion of a pulmonary artery catheter (flotation or flow-directed)?
Air in the manometer tubing may result in over-estimation of the pulmonary artery occlusion pressure
Associated with a less than 10% incidence of arrhythmias
Associated with rupture of a pulmonary vein
Contraindicated in the presence of right bundle branch block
Facilitated during deep inspiration in a spontaneously ventilating patient
The complications associated with the insertion of pulmonary artery catheters (PACs) include:
Arrhythmias (up to 70%)
Right bundle branch block
Pulmonary infarction
Pulmonary artery (not vein) rupture (0.2%)
Sepsis
Knotting of the catheter
Endocrinal damage
Central venous cannulation (arterial puncture, pneumothorax, air embolism).
For the PAC to enter the pulmonary circulation, it should be advanced during maximal pulmonary blood flow (inspiration with spontaneous ventilation and expiration with positive pressure ventilation).
The manometer tubing connecting the pressure transducer to the PAC is fluid filled and it should be free of air bubbles, the presence of which can result in damping of the trace and under-estimation of the pulmonary artery occlusion pressure.
41
Which of the following is true regarding electrocardiogram (ECG) interpretation
0.16 seconds represents a normal QRS duration
50 mm per second is the standard paper speed
Standard calibration implies that 0.1 mV is equivalent to a deflection of 1 cm
The P-R interval is measured from the start of the P wave to the start of the QRS complex
The Q-T interval is measured from the start of the QRS complex to the start of the T wave
The standard paper speed for recording the ECG is 25 mm per second and 1 mm corresponds to 0.04 seconds.
The standard calibration of voltage deflections is 0.1 mV equals 1 mm.
The P wave represents atrial depolarisation. Atrial repolarisation occurs during the P-R interval and the QRS complex. The P-R interval is measured from the start of the P wave to the start of the QRS complex and is normally between 0.12 and 0.2 seconds. It serves as a rough approximation of atrioventricular conduction time.
The QRS complex represents ventricular depolarisation and is normally less than 0.12 seconds. The Q-T interval is measured from the start of the QRS complex to the end of the T wave. It approximates to the ventricular refractory period and is normally 0.42 seconds.
The S-T segment is measured from the end of the QRS complex to the start of the T wave. It represents the time period between ventricular depolarisation and ventricular repolarisation. The T wave is produced by ventricular repolarisation.
42
Which of the following is true in disorders of cardiac conduction?
Deep S waves are found in leads I and V6 in left bundle branch block
Left anterior hemiblock causes right axis deviation
Left posterior hemiblock causes left axis deviation
Right bundle branch block and left axis deviation indicate bifascicular block
Right ventricular hypertrophy cannot be diagnosed in the presence of right bundle branch block
Right bundle branch block and left axis deviation indicate bifascicular block
The bundle of His consists of three fascicles
1.The right bundle branch
2.The anterior fascicle of the left bundle branch
3.The posterior fascicle of the left bundle branch.
Bifascicular block describes the combination of right bundle branch and either left anterior or left posterior hemiblock. Left anterior hemiblock causes left axis deviation, and left posterior hemiblock causes right axis deviation.
A-V conduction is maintained by the remaining functional fascicle. Impaired conduction in the latter may be manifest by a prolonged P-R interval.
Bifascicular block may progress to trifascicular block and may be an indication for the insertion of a permanent cardiac pacemaker.
Right bundle branch block (RBBB) in isolation is a normal ECG variant. The delayed right ventricular depolarisation results in a second positive wave in the right ventricular leads, and a second negative wave in the left ventricular leads.
Diagnostic features include
Widened QRS complex
Second positive wave in V1.
Other features include
Deep slurred S waves in leads I, aVL, V4-6
S-T segment
T wave changes in leads V1-3.
Left bundle branch block (LBBB) is always pathological. In the presence of LBBB, the diagnosis of ventricular hypertrophy, myocardial ischaemia/infarction, and abnormalities of the P wave, QRS complex or S-T segment cannot be made using conventional ECG criteria.
43
Which of the following features is compatible with hypertension?
```
Fifth heart sound
Loud aortic second heart sound
Retinal haemorrhages and soft exudates, indicating a grade 2 hypertensive retinopathy
Tapping apex beat
Third heart sound
```
Loud aortic second heart sound
Hypertensive patients usually have no specific symptoms or signs. Abnormal signs usually only appear after a period of prolonged, severe hypertension.
A fourth heart sound is due to increased atrial activity. It occurs in diastole, preceding the first heart sound and can occur in any form of left ventricular disease.
Hypertension is associated with left ventricular hypertrophy and causes a thrusting apex beat, in contrast to the tapping apex beat characteristic of mitral stenosis.
A loud aortic second heart sound is a classical finding in hypertension. A third heart sound may be a normal finding in patients under 40 years of age.
A pathological third heart sound occurs with
```
Mitral and tricuspid regurgitation
Constrictive pericarditis
A dilated left ventricle
Acute myocardial infarction.
Hypertensive retinopathy is graded as follows:
```
1. Grade 1 - arterial narrowing
2. Grade 2 - arteriovenous nipping
3. Grade 3 - haemorrhages and exudates
4. Grade 4 - all of the above plus papilloedema
44
With which of the following is hyperkalaemia associated?
Hyperactive reflexes
Inverted T waves on the electrocardiogram
Muscle weakness
QRS narrowing on the electrocardiogram
U waves on the electrocardiogram
Muscle weakness
Hyperkalaemia causes
```
Electrocardiogram abnormalities
Peaked T waves
Prolongation of the PR interval
QRS widening
Decreased P waves
Heart block
Arrhythmias
Muscle abnormalities
Weakness
Paraesthesia
Hypoactive reflexes.
U waves on the electrocardiogram are seen in hypokalaemia.
```
45
Which of the following is true concerning the central venous pressure (CVP) trace?
The C wave represents atrial contraction
The V wave represents ventricular contraction
Third degree heart block causes canon A waves
Tricuspid regurgitation causes large A waves
X descent occurs between the A and C waves
Third degree heart block causes canon A waves
A waves represent atrial contraction.
C waves correspond to the tricuspid valve bulging into the atrium during right ventricle contraction.
V waves represent atrial filling with a closed tricuspid valve.
X descent occurs following the C wave.
Large A waves occur with right ventricular hypertrophy and complete heart block.
Tricuspid regurgitation causes giant V waves.
46
Which of the following is true regarding intra-abdominal pressure?
A pressure of 5-10 mmHg is normal
Causes abdominal compartment syndrome when >15 mmHg
If elevated may cause an increase in systemic vascular resistance
May be measured in the oesophagus
Surgical decompression is indicated if intra-abdominal pressure is >10 mmHg
If elevated may cause an increase in systemic vascular resistance
The normal intra-abdominal pressure is zero or sub-atmospheric.
When the intra-abdominal pressure is greater than 25 mmHg the abdominal compartment syndrome can occur, which usually requires surgical decompression.
The systemic vascular resistance (SVR) is often found to be increased when the intra-abdominal pressure is high.
It can be measured directly at laparoscopy, or indirectly via the femoral vein, stomach, rectum and bladder.
47
Which of the following is true regarding the anion gap?
```
Depends on plasma magnesium
Is decreased in diabetic ketoacidosis
Is normal with lactic acidosis
Normal value is 2-8 mmol/l
The gap is partially due to phosphate
```
The anion gap is a method of assessing the contribution of unmeasured anions to acidosis.
It is calculated as a difference between the total of sodium and potassium concentration, minus the total of chloride and bicarbonate concentration. Some people omit the potassium. Thus:
Anion Gap = [K+] + [Na+] - [Cl-] - [HCO3-] (plasma concentrations)
The normal range for the anion gap is 8 to 16 mmol/l. The anion gap provides a measure of the difference between unestimated anions - phosphate, acetate and ketones - and cations.
The anion gap is likely to be abnormally high in most conditions of acidosis except
Renal tubular acidosis
Treatment with acetazolamide
Ureteric implantation into the colon.
When a metabolic acidosis is due to bicarbonate loss from gut or kidneys, the anion gap may be normal. The anion gap may be elevated when fixed or organic acids (for example, ketoacidosis, lactic acidosis, uraemia, drugs) are retained.
48
Which of the following is a diagnostic feature of a left-sided tension pneumothorax?
```
Increased breath sounds on the left
Left side is dull to percussion
Pulsus paradoxus
Raised jugular venous pressure (JVP)
Tracheal deviation to the left
```
A tension pneumothorax results in
Deviation of the trachea away from the side
Decreased venous return causing an elevated jugular venous pressure (JVP) or distended neck veins
Hyper-resonance to percussion
Decreased breath sounds.
Pulsus paradoxus occurs in asthma and cardiac tamponade.
49
Hyponatraemia is a recognised feature of which of the following?
```
Conn's syndrome
Hyperthyroidism
Post-operative pneumonic consolidation
Steroid therapy
Teratoma
```
Post-operative pneumonic consolidation
Hyponatraemia is the commonest biochemical abnormality, occurring in up to 10% of hospitalised patients.
Causes of hyponatraemia include
SIADH (subarachnoid haemorrhage, pneumonia)
Hypothyroidism
Addison's disease
Diuretic therapy.
Steroid therapy would cause salt and water retention, as does Conn's syndrome.
It is not a feature of teratoma.
50
Which of the following is true of percutaneous needle biopsy of the liver?
Is indicated to make a tissue diagnosis in suspected hydatid disease of the liver
Is associated with a mortality rate of 0.5%
Is associated with a recognised risk of pneumothorax
Should be avoided in suspected metastatic disease of the liver
Should only be performed with a normal coagulation screen
Is associated with a recognised risk of pneumothorax
Needle biopsy of the liver is not without risk, with bleeding being the most common side effect but fatal complications have been reported in up to 0.1% of biopsied patients (range 0.009-0.1%).
In fact, pneumothorax, although rare is also recognised.
Although a normal coagulation profile is ideal, it is not essential for the procedure. It should not be performed in patients with suspected hydatid disease because of the risk of seeding.
However, malignancy is not a contra-indication and needle biopsy is often performed to elucidate potential malignant deposits.
51
Disseminated intravascular coagulation (DIC) is not a recognised complication of which of the following?
```
Eclampsia
Endometriosis
Ovarian carcinoma
Placental abruption
Placenta praevia
```
Endometriosis
DIC occurs in numerous obstetric conditions including placenta praevia and abruptio.
It is also associated with
Infections
Carcinoma
Amniotic fluid embolism and
Eclampsia.
52
Prothrombin time is not increased in which of the following?
```
Aspirin therapy
Cirrhosis
Disseminated intravascular coagulation
Unfractionated heparin therapy
Warfarin therapy
```
The prothrombin time (PT) measures the clotting time from the activation of factor VII, through the formation of fibrin clot.
This test measures the integrity of the extrinsic and common pathways of coagulation, whereas the activated partial thromboplastin time (PTT) measures the integrity of the intrinsic and common pathways of coagulation.
Causes of prolonged PT include
Warfarin therapy
Unfractionated heparin (not low molecular weight)
Disseminated intravascular coagulation and
Liver diseases.
Aspirin has no impact on the coagulation cascade.
53
Of which of the following is weight loss a typical feature?
```
Hyperparathyroidism
Hypothyroidism
Insulinoma
Phaeochromocytoma
Polycystic ovarian syndrome
```
Phaeochromocytoma
Weight loss is a feature of hyperthyroidism but not hypothyroidism and is not typical of hyperparathyroidism.
It is associated with a phaeochromocytoma which is multifactorial but the sympathetic overdrive is implicated.
PCOs is, of course, associated with weight gain, hirsutism and oligomenorrhoea.
Weight gain is more typical of an insulinoma due to stimulated appetite.
54
Which of the following is true of mammographic screening for breast cancer?
Has been shown to reduce mortality from breast cancer in women over the age of 50
Has no evidence to support screening beyond the age of 70
Is associated with a false positive rate of approximately 15%
Should be offered more frequently to women on HRT
Mammographic screening for breast cancer has a high sensitivity and specificity, with a false positive rate of less than 10% in younger females, which is even better in older women (5%).
Screening is advocated every two to three years in women above the age of 50. There is no evidence to support more frequent screening.
Women beyond 70 years of age have an increased risk of breast cancer and it may be more readily demonstrated in this age group with mammography.
55
Which of the following is true of colorectal cancer?:
Affects females more commonly than males
Risk is associated with the decreased intake of dietary fat
Risk is elevated in patients with obesity
Risk is elevated in postmenopausal females taking hormone replacement therapy
Risk is higher in lower social classes
Obesity
Colorectal carcinoma is the fourth most common cancer in males and females and affects the sexes equally.
No specific difference in incidence has been identified between the sexes and there is no obvious increased risk with obesity. Yet dietary fat and lower social class have been implicated.
Although breast cancer risk increases with HRT use, the Women's Health Initiative showed a reduced incidence of colorectal cancer associated with HRT use.
56
Which of the following is not a tumour suppressor gene?
```
APC
BRAC1
c-myc
p53
VHL
```
c-myc
Mutations in tumour suppressor genes have been implicated in malignancy as down regulation of these genes can result in the unrestricted growth of cells and hence predispose to malignancy.
These genes include VHL (von Hippel-Lindau), p53, Rb1 (retinoblastoma), BRAC and APC (adenomatous polyposis coli) genes.
Oncogenes, on the other hand are associated with the promotion of cell division and include myc, erb, ras and ret.
57
Which of the following oncogenes is associated with the development of breast cancer?
```
BCL-2
BRAC3
HER-2
N-MYC
RET
```
BRAC1 and 2 together with HER - the human epidermal growth factor receptor mutations are well recognised to be associated with breast cancer.
The loss of the tumour suppressor gene p53 is also associated with many carcinomas.
RET is associated with thyroid malignancy, whilst BCL-2 is associated with lymphomas.
N-myc (unlike c-myc which is associated with breast neoplasia) is associated with cerebral malignancy.
58
Which one of the following cancers has a five year survival greater than 50%?
```
Colon
Lung
Melanoma
Pancreatic
Stomach
```
Melanoma has a five year survival rate of 78-90%.
The five year survival of
```
Pancreatic is 2-3%
Colon is 45-46%
Lung is 6% and
Stomach is 12-13%.
(Cancer Research UK: Relative five-year survival estimates based on survival probabilities observed during 2000-2001, England and Wales).
```
59
Which of the following viruses is not associated with human cancers?
```
Epstein-Barr virus
Hepatitis B virus
Human papilloma virus
Mumps virus
Polio virus
```
EBV is associated with a rare tumour- Burkitt's lymphoma as well as nasopharyngeal cancers.
HPV is associated with cervical carcinoma.
One of the risk factors for testicular cancer is mumps orchitis in childhood.
Hepatitis B virus is associated with hepatocellular carcinoma in association with chronic liver disease.
60
Hormones synthesised by the kidney include which of the following?
```
1,25 dihydroxycholecalciferol
Aldosterone
Angiotensin I
Angiotensin II
Cortisol
```
The kidney is responsible for the manufacture of renin which acts on the circulating peptide angiotensinogen to convert it to angiotensin I which is then further cleaved in the lungs to angiotensin II.
This acts on the adrenal cortex to release aldosterone.
The kidney also manufactures 1,25 dihydroxyvitamin D (hence hypocalcaemia in chronic renal failure) and is also responsible for the synthesis of erythropoietin.
Aldosterone and cortisol are synthesised by the adrenal cortex.
61
Of which of the following is an elevated alkaline phosphatase concentration a typical feature?
```
Gilbert's syndrome
Osteoporosis
Paget's disease
Peptic ulceration
Pulmonary embolism
```
Alkaline phosphatase isoenzymes are found in liver and bone and may be raised in hepatic cholestasis or through any bony involvement.
It is not however raised in osteoporosis and is not elevated with pulmonary embolism or peptic ulceration.
Similarly, in Gilbert's syndrome there is no cholestasis and alkaline phosphatase is typically normal.
Slight elevation is seen in the last trimester of pregnancy.
62
Which of the following is true regarding directional airflow in theatre?
May be vertical or horizontal
Produces turbulent airflow
Produces 20-40 air changes per minute
The air is pumped in through filters and out of vents in the periphery of theatre
Work with the aid of negative pressure
The air is pumped in through filters and out of vents in the periphery of theatre
The correct answer is that the air is pumped in through filters and out of vents in the periphery of theatre, producing flow in a clean to dirty direction.
The directional (laminar) airflow is in addition to the normal turbulent airflow in theatre which maintains humidity and temperature. This directional airflow produces non-turbulent flow.
Most theatres have 20-40 air changes per hour, as opposed to 20-40 air changes per minute. This increased rate of air change is necessary to reduce the number of contaminated particles over the patient.
The directional airflow in theatre works with positive pressure as air is pumped into theatre through filters.
63
Which one of the following leucocytes arrive in the wound first following wounding?
```
Basophils
Eosinophil
Lymphocytes
Macrophages
Neutrophils
```
Neutrophils
Following wounding the first event to occur is haemostasis/coagulation, which results from the interaction of platelets trapping the erythrocytes lost into the wound.
Neutrophils enter the wound within a few hours these are followed by macrophages (one to two days after wounding).
Lymphocytes enter much later and in greater numbers if infection is present.
64
Which one of the following regarding properties of laser is untrue?
All the photons are in phase
All the photons have the same wavelengths
It is entirely monochromatic
The distance between the mirrors within a laser tube is a multiple of the wavelength of the light emitted
The waves of light are parallel
Laser is virtually monochromatic but not entirely so.
It is coherent, that is, photons have the same wavelength and in phase and collimated, that is, the light waves are parallel.
The laser tube contains two mirrors with the distance between them a multiple of the light wavelength.
65
With respect to the heart, which of the following is correct?
At rest, denervation of the heart would result in a rise in heart rate
In exercise, systole shortens more than diastole
Sympathetic stimulation decreases the force of atrial contraction
The spread of excitation through the walls of the ventricles is from the outside the ventricular wall inwards
Vagal stimulation decreases the force of ventricular contraction
At rest, denervation of the heart would result in a rise in heart rate
The excitation impulse is spread from the endocardial surface outwards with vagal stimuli reducing heart rate rather than force.
Sympathetic stimulation causes increased heart rate and increased atrial contraction.
With increased heart rate there is a greater shortening of diastole. This is because vagal tone would be removed and the heart would beat at its intrinsic rate (about 100 beats per minute).
66
When a normal person lies down, which of the following is correct?
Blood flow in the apices of the lungs decreases
Cerebral blood flow settles to a higher level than when standing
Heart rate settles to a higher level than when standing
Lower limb veins constrict actively
Venous return (VR) is immediately increased
Venous return (VR) is immediately increased
After initially lying down there is a rise in BP, increased VR and hence reduction in heart rate because gravity normally has an effect in the standing position giving lower perfusion in the upper parts of the lungs when compared with the base.
67
Concerning the electrocardiogram (ECG) of an adult human:
A P-R interval of 0.15 seconds indicates impaired conduction
During the isoelectric phase between the S and T waves, the intracellular potential in ventricular muscle cells is negative with respect to the interstitial fluid
Normal QT interval is 0.5 s
The Q wave coincides with depolarisation of the atria
The R wave coincides with depolarisation of the apex of the heart
The R wave coincides with depolarisation of the apex of the heart
A P-R interval of 0.15 seconds indicates impaired conduction
During the isoelectric phase between the S and T waves, the intracellular potential in ventricular muscle cells is negative with respect to the interstitial fluid
Normal QT interval is 0.5 s
The Q wave coincides with depolarisation of the atria
The R wave coincides with depolarisation of the apex of the heart
68
In the normal human heart, which of the following is correct?
0.3s corresponds to a normal PR interval
The duration of the action potential in a ventricular muscle fibre is about the same as in a skeletal muscle fibre
The last part of the ventricle to be activated is the apex
The most quickly conducting fibres in the heart are the Purkinje fibres
The T-wave of the ECG occurs at the beginning of the absolute refractory period of the ventricle
The Purkinje fibres conduct at about 4m/s (against ~1m/s in ventricular and atrial muscle).
The Bundles of His are activated at the AVN and travel to the apex from whence they activate the lateral walls of the heart.
The P wave of the ECG corresponds to atrial contraction, QRS ventricular and T wave ventricular relaxation. The duration of the ap of a cardiomyocyte is much longer than that of a skeletal muscle fibre.
Normal PR interval is 0.12-0.2s, QRS duration less than 0.12s and QT interval less than 0.42s.
69
When blood passes through systemic capillaries, which of the following is correct?
CO2 diffuses into plasma and the red blood cells; HCO3- is formed faster in the RBCs because of carbonic anhydrase and therefore HCO3- moves out of the cells into the plasma.
The rise in CO2 shifts the curve to the right (Bohr effect), that is, with an increased Pco2 haemoglobin has a diminished ability to bind O2 and therefore gives it up to the tissue more readily.
Increasing temperature and a decrease in pH will also cause a rightward shift in the curve.
Even though the volume must be the same as that in the aorta, the flow must be lower because the total cross sectional area is greater.
70
Which of the following is synthesised in the liver?
```
Alpha1 antitrypsin
Cytokines
Immunoglobulin IgA
Thromboxane A2
Vitamin B12
```
Caeruloplasmin, Alpha 1 antitrypsin and prothrombin are synthesised in the liver.
Cytokines are principally secreted by macrophages.
Vitamin B12 is synthesised by bacteria and found in meat, eggs and dairy products. It is absorbed in the terminal ilem and stored in the liver.
Thromboxane A2 is derived from arachidonic acid.
IgA is synthesised by lymphocytes in mucosal surfaces.
71
Features of biliary atresia include which of the following?
```
Dark stools
Normal excretion of isotope into duodenum in HIDA scan
Osteoarthritis
Prolonged hyperbilirubinaemia
Unconjugated hyperbilirubinaemia
```
```
Chalk-coloured stools
Dark urine
Weight loss
Jaundice and
Abdominal distension
are characteristic of biliary atresia.
```
Breast milk jaundice is a benign self limiting condition causing unconjugated hyperbilirubinaemia; biliary atesia causes prolonged obstructive jaundice.
If the isotope passes from the liver into the duodenum the bile ducts would be patent, unlike in biliary atresia.
Osteoporosis and osteomalacia are potential consequences of vitamin D malabsorbtion.
72
Which of the following is true with regard to the thyroid gland?
A thyroglossal cyst is usually an embryological remnant
It develops from the third branchial arch
It is not fully developed until the second year of life
The presence of lingual thyroid could lead to hyperthyroidism
The thyroglossal duct is closely related to the thyroid
A thyroglossal cyst is usually an embryological remnant
The thyroid gland is fully developed at birth.
The development starts as early as 4 weeks of intrauterine life and is fully complete by 6 weeks.
The thyroid develops from the caudal end of the thyroglossal duct. The thyroglossal duct extends from the foramen caecum in the tongue to the neck.
A thyroglossal cyst develops from the epithelial remnants in the thyroglossal duct. The cyst appears in the first decade of life and is attached to the hyoid bone; hence removal of the cyst necessitates removal of the body of the hyoid bone.
The lingual thyroid may be the only thyroid tissue, and hence the patient may be hypothyroid or euthyroid.
73
Which of the following is true concerning grief reactions?
Angry outbursts are an atypical feature of the natural grieving process
Antidepressants is the most appropriate initial therapy
Grief reactions may occur many years after the death of the person
Hallucinations of the deceased are an abnormal feature of the normal grief reaction
Suicidal ideations are a common feature of a grief reaction
Grief reactions may occur many years after the death of the person
Grief reactions are typically mapped along the lines of anger, denial and guilt.
Delayed grief is said to occur if it commences two weeks after bereavement.
Grief reactions often occur on anniversaries such as weddings, births etc.
The most appropriate treatment is counselling and antidepressants should not be routinely used.
Suicidal ideations are also abnormal.
74
In proximal femoral fractures which of the following is correct?
Avascular necrosis of the femoral head is a serious complication of intracapsular fractures.
Extracapsular fractures have the greatest risk of non-union
Fractures of the femoral head are more common in the old
Gardens' classification of proximal femoral fractures is based on oblique radiographic images
Avascular necrosis of the femoral head is a serious complication of intracapsular fractures.
Fractures of the femoral head are more common in the young, and are associated with trauma and traumatic dislocation of the hip joint.
Intracapsular fractures have a higher risk of non-union since the blood supply to the femoral head is distal to proximal. Therefore, avascular necrosis of the femoral head is a serious complication of intracapsular fractures.
Gardens' classification of proximal femoral fractures is based on antero-posterior radiograph images and it describes the relationship of displacements between the femoral head, femoral neck and the acetabulum.
Extracapsular fractures are usually managed by dynamic sliding (hip) screws or plates and reconstruction nail or intramedullary hip screw in more severe types.
75
Which of the following is true regarding polyglactin 910 (Vicryl):
Absorbs completely in 60 days.
Allows capillarity
Handling properties are similar to Prolene
Is a monofilament synthetic absorbable suture Incorrect answer selected
Loses tensile strength more rapidly than polyglycolic (Dexon)
Allows capillarity
Vicryl is a braided synthetic absorbable suture.
Dexon loses tensile strength more rapidly and is absorbed more slowly than Vicryl.
Vicryl absorbs completely in 30 days, Dexon absorbs completely in 120 days, polydioxanone synthetic (PDS) absorbs completely in 180 days.
Both silk and Vicryl knot easily and the knots hold well unlike the monofilament Prolene.
Capillarity refers to the characteristic that allows the passage of tissue fluids along the strand, permitting infection to be drawn into the wound.
76
Which one of the following is an example of a closed biopsy technique?
```
Excision biopsy
Frozen section biopsy
Shave biopsy
Tru-cut needle biopsy
Wedge biopsy
```
Biopsies are divided into two main groups:
Open direct biopsies
Closed indirect biopsies
Excision biopsy involves removal of the entire lesion usually with a margin of healthy tissue.
A frozen section biopsy is an example of an open direct biopsy. This technique allows for a tentative diagnosis in 10-15 minutes, allowing the surgeon to proceed with a definitive procedure.
A shave biopsy is performed with a small scalpel blade or a curved razor blade. Ideally only a small fragment of protruding tumour is removed leaving the skin relatively flat after the procedure. The technique is ideal for the diagnosis/management of basal cell carcinomas.
A Tru-cut biopsy takes a core of tissue (breast mass or prostate) using a specialised needle and sheath.
A wedge biopsy is an example of an open direct biopsy. A wedge of the lesion (ulcer or tumour) is taken including the margin and normal surrounding skin for histological comparison.
77
Which of the following is correct in multiple organ dysfunction syndrome (MODS)?
Secondary MODS occurs when organ dysfunction is a consequence of the host's response
The mortality is up to 20%
The phenomenon is irreversible
The renal system often deteriorates first
The sequence of organ dysfunction is not associated by the site of the original insult
Secondary MODS occurs when organ dysfunction is a consequence of the host's response
The respiratory system often deteriorates first.
The organs involved and the sequence of their dysfunction are determined by the original insult.
Mortality increases with the number of organ systems affected and with the severity of physiological disturbance at onset.
Prompt intervention can reverse organ dysfunction.
Primary MODS is a direct consequence of a specific insult that causes early dysfunction of the organs involved.
78
Which one of the following definitions regarding the sepsis sequelae is correct?
Sepsis is an inflammatory response to microorganisms or their invasion of normal sterile host tissue
Septicaemia is a clinically symptomatic exotoxaemia
Septic shock is sepsis with hypotension and hypoperfusion despite adequate fluid resuscitation
Severe sepsis is the systemic inflammatory response syndrome (SIRS) plus a confirmed infective process
Systemic inflammatory response syndrome (SIRS) is the alteration of organ function in acute illness such that homeostasis cannot be maintained without intervention
Septic shock is sepsis with hypotension and hypoperfusion despite adequate fluid resuscitation
SIRS is defined by the presence of two or more of the following:
Temperature >38°C or 90 beats/min
Respiratory rate >20 per min or an arterial partial pressure of CO2 (PaC02) 12 or
79
The diagnosis of the systemic inflammatory response syndrome (SIRS) requires which of the following?
```
Erythrocyte sedimentation rate (ESR) >30
Pulse >80 beats/min
Respiratory rate >30 per min
Temperature >39°C
White cell count >12,000 cells/ml
```
The diagnosis of SIRS requires two or more of listed parameters to be abnormal:
Temperature >38°C, or 90 beats/min
Respiratory rate >20 per min or an arterial partial pressure of carbon dioxide (PaCO2) 12,000 cells/ml or
80
Safe positioning of a patient on the operating table requires which of the following?
Minimal movements of the arms
Removal of lumbar supports
Requires spinal injury patients to be operated on the bed to avoid injuries during transfer
The legs to be rested against the support bar when the patient is in the lithotomy position
Transfer from the trolley to the operating table by lifting
Minimal movements of the arms
Lifting of patients should be avoided to prevent risk of injury to staff.
Instead patients should be slid from trolley to operating table using a Patslide (a tough plastic board with a low coefficient of friction, which acts as a bridge to enable the patient to be slid rather than lifted).
Soft cushions or partially filled intravenous fluid bags are used to support the lumbar lordosis.
The common peroneal nerve may be damaged by pressure against a leg support bar.
The brachial plexus is prone to injury with excessive arm movement.
Patients with spinal injuries or symptomatic osteoarthritis should have their transfer rehearsed by the staff prior to movement to avoid unnecessary injuries.
81
Which of the following is true of a good scrub-up technique?
Removes deeper organisms from hair follicles and sweat glands
Requires a minimum of 10 minutes
Requires hand skin boils to be covered prior to scrubbing
Requires the nails and skin to be scrubbed with a nail brush
Using chlorhexidine kills organisms for up to 2 hours after scrubbing
Using chlorhexidine kills organisms for up to 2 hours after scrubbing
The aim of pre-operative scrubbing is to remove surface organisms from the hands and forearms. The technique does not remove deeper organisms.
Povidone iodine and chlorhexidine kill organisms for up to two hours.
The hands and forearms are lightly washed, the fingernails are then scrubbed with povidone iodine/chlorhexidine and a nail brush. The hands and forearms are then washed for a further two minutes, rinsed and dried. There is no advantage to excessive and lengthy scrubbing.
Only the nails require scrubbing. Scrubbing the skin with a nail brush increases the release of skin bacteria.
Staff skin infections should not be in theatre until recovery is complete.
82
Theatre etiquette dictates which of the following?
Only the minimum number of people should be in theatre
Patients should only enter and leave via the anaesthetic room
Patients must have the operation site shaved the day before surgery
Theatre instruments should enter and leave theatre by the same route
Woven non-disposable drapes should be used
Only the minimum number of people should be in theatre
The bacteriology count in theatre is related to the number of persons and their movement in the operating theatre.
As theatre air flows from clean to dirty, the patient should enter theatre via the anaesthetic room and leave via another route.
Patients must have hair removed from the operation site either immediately before coming to theatre or preferably in theatre. Shaving before surgery produces folliculitis and increases the wound infection rate.
Used instruments should leave theatre via another exit to the disposal area.
The use of laundered and re-autoclaved drapes is no longer encouraged.
83
An operating theatre is divided into a number of zones, including which of the following?
```
Anaesthetic zone
Dirty zone
Inner zone
Operating zone
Recovery zone
```
Dirty zone
An operating theatre is organised to minimise bacterial contamination.
The outer zone involves the patient reception area and recovery.
The area between the reception bay and the operating theatre is the clean zone and includes the anaesthetic room.
The dirty zone includes the disposal areas and the dirty corridor.
The aseptic zone is the operating theatre.
84
Operating theatres should be situated in which of the following areas?
```
Adjacent to anaesthetic department
Adjacent to blood bank
Adjacent to the accident and emergency department
Next to the intensive care unit
On the ground floor
```
Next to the intensive care unit
Theatres should preferably be situated on the first floor away from the main hospital traffic. Ideally they should be on the same floor or adjacent to the intensive care unit.
Accident and emergency departments should be situated on the ground floor.
There should be a minimum distance from the accident and emergency department and theatres.
The anaesthetic department should be sited well away from main theatres in order to keep the anaesthetists fit.
Theatres should preferably be situated on the same floor or adjacent to the surgical wards.
Blood banks should be close to theatre if possible but do not need to be adjacent.
85
Which of the following is correct in a laser control area (LCA)?
Adequate ventilation must be provided
All surfaces must be coated in matt black paint
Eye protection is optional
Only a laser safety officer (LSO) is permitted to use the laser
Only the person discharging the laser is permitted to be present
Adequate ventilation must be provided
An LSO is appointed from the staff of each department using the laser and has custody of the laser key.
All persons using a laser should be suitably trained and be aware of all safety precautions. There should be a control of personnel allowed to enter the area and the entrance should be marked with appropriate illuminated warning signs.
Reflective surfaces should be avoided. However, matt black surfaces are not necessary.
Eye protection must be appropriate to the type of laser being used.
The ventilation should include an extraction system to vent the fumes produced.
86
Which one of the following classes of lasers is considered to be of low risk?
```
Class 5
Class 4
Class 3b
Class 3a
Class 2
```
A Class 5 laser is capable of burning objects directly exposed to energy.
Class 4 is considered high risk. These are high powered devices with a potential fire hazard. Most medical lasers are in this class.
Class 3b is considered a medium risk. Direct viewing may be a risk.
Class 3a is considered low risk but may be a hazard if the beam is optically focused.
Class 2 is considered low risk. These are low power devices emitting visible radiation. Safety is normally afforded by natural aversion responses.
Class 1 is considered low risk. These are low power devices emitting radiation below the maximum permissible exposure (MPE).
87
Which one of the following is an example of lasers commonly used in surgery?
```
Carbon monoxide
Helium
Magnesium
NdYAG
Silicon
```
Carbon dioxide is an example of a gaseous lasing medium commonly being employed in colposcopy.
NdYAG (Neodymium Yttrium Aluminium Garnet) is an example of a crystalline lasing medium commonly being employed in endoscopes.
88
Which of the following are true of laser?
Is an acronym for Light Amplification of Stimulated Ejection of Radiation
Lasing medium must be liquid
Produces multichromatic light
Requires a pair of mirrors at opposite ends of an optical cavity containing the lasing medium
Wavelength is determined by the stimulating current
Is an acronym for Light Amplification of Stimulated Emission of Radiation.
A laser produces a highly directional beam of coherent (monochromatic) electromagnetic radiation.
Photons of energy produced from energised atoms in the lasing medium are reflected back and forth many times between the mirrors amplifying their number.
The lasing medium determines the wavelength of electromagnetic radiation emitted.
The lasing medium is most commonly gaseous but may be crystalline.
89
Which one of the following increases the risk of an inadvertant laparoscopic diathermy injury?
A carbon dioxide pneumoperitoneum
Adequate views of the operation field
Avoid touching other instruments when the active electrode is in use
Good insulation of the active electrode only
Use of the lowest diathermy current possible
Avoiding touching other instruments prevents inadvertent burns out of view of the operator.
All laparoscopic instruments require good insulation to prevent inadvertent contact and sparking.
Good views of the operation field are essential.
Carbon dioxide is an inert gas which prevents sparking when diathermy is used.
Lower currents or bipolar diathermy minimise spread of current and sparking.
90
Does safe diathermy use include any of the following?
Avoiding using diathermy on the colon
Increasing the current slowly if the diathermy performance is poor
Only requires placing the active electrode in the insulating quiver when peritoneal lavage is performed
The assistant should press the diathermy pedal, allowing the surgeon to concentrate on the operation
The theatre nurse should check the diathermy settings before starting the operation
The colon contains hydrogen and methane therefore diathermy use on the colon is an explosive risk.
Only the surgeon wielding the active electrode should activate the machine. The dial setting should be checked by the surgeon operating before the operation starts. The active electrode should always be placed in the insulating quiver when not in use as this prevents inadvertent burns.
If diathermy performance is poor the plate and lead should be checked and replaced if necessary
91
Which one of the following is true of diathermy safety features?
Only isolated diathermy machines alarm when switched on if the plate is not connected to the machine
Shave the skin in contact with the diathermy plate if the patient is hairy
The area under the plate should have a good blood supply
The patient plate is applied to ensure the current is moving towards the electrocardiogram electrodes
The person who applies the diathermy plate is responsible for its correct application
Only isolated diathermy machines alarm when switched on if the plate is not connected to the machine
Shave the skin in contact with the diathermy plate if the patient is hairy Incorrect answer selected
The area under the plate should have a good blood supply This is the correct answer
The patient plate is applied to ensure the current is moving towards the electrocardiogram electrodes
The person who applies the diathermy plate is responsible for its correct application
92
Which of the following is true of isolated diathermy machines?
Are earth referenced generators
Are inherently safer
Can only pass current back to the generator via the patient plate
Operate in a frequency range of 400-600 kHz
Produce unavoidable large earth leakage currents
Modern diathermy machines are isolated (unearthed) generators as opposed to the old earth referenced generators.
The old earth referenced generators tend to produce higher frequency current over a wider range than the narrow range of the isolated generators.
Current will only pass back to the generator with no pathway back to earth, that is, a small area of skin touching a metal contact (for example, drip stand) will not result in a burn.
If the plate is omitted current will not flow.
The sophisticated electronics in the isolated generator ensure a considerable reduction in earth leakage currents compared to the earth referenced generators.
93
Which of the following is true regarding monopolar diathermy?
Blend facility only functions in the coagulation mode
Plate must be at least 20 cm2
Produces cutting diathermy at temperatures of up to 500 degrees centigrade
Produces local coagulation by a local heating effect
Spreads current from the plate to the electrode (diathermy point)
In monopolar diathermy the high frequency alternating current (AC) passes through the active electrode (diathermy tip) which has a very small surface area producing a powerful heating affect.
The current passes from the diathermy tip to the plate. The plate should be in good contact with the patient and be a minimum of 70 cm2. Misapplication of the patient plate is the commonest cause of inadvertent diathermy burns.
Cell water is instantly vaporised causing tissue disruption and a degree of coagulation.
The blend facility only functions in the cutting mode, allowing a combination of cutting and coagulation to increase the degree of haemostasis during cutting.
94
Which one of the following is true in the selection of suture needle types?
A blunt round point is the needle of choice in tendon repairs
A blunt taperpoint is the needle of choice in ligament repairs
A reverse cutting needle should be used in a mass closure
A round bodied needle is used in a bowel anastomosis
A TapercutTM is the needle of choice to suture liver
A TapercutTM combines the initial penetration of a cutting needle with the minimised trauma of the round-bodied needle. The cutting tip is limited to the point of the needle. This is the needle of choice for fascia, ligament or scar tissue.
Blunt taperpoint is the needle of choice when needlestick injury is a major concern (high risk patients).
On a reverse cutting needle the body is triangular in cross section with the apex on the outside of the needle curvature. This the needle of choice in skin, ligament and tendon.
Round bodied needles are designed to separate tissue fibres rather than cut them. After the passage of the needle the tissue closes tightly round the suture material, therefore forming a leak proof suture line making them the needle of choice in bowel and vascular anstomosis.
A blunt point needle has been designed for suturing extremely friable vascular tissue, for example, liver, spleen and kidney.
95
Which one of the following is true of suture material?
Absorbable sutures can cause buttonhole hernias
Jenkins rule dictates the length of suture to be used in an amputation stump
Only fine non-absorbable sutures should be used in a vascular anastomosis
Persistent infection and sinus formation is more common with non-braided sutures
The choice of suture should be dictated by the surgeon's preference
The choice of suture is dictated by the expected rate of healing of the tissue being sutured.
The process of capillarity (the characteristic that allows the passage of tissue fluid along the strands) is more common with braided sutures.
Jenkins rule (the suture material should be four times the length of the wound and each bite should be 1 cm deep and 1 cm apart) applies to the mass closure technique of the rectus.
Monofilament Prolene is the suture of choice in vascular anastomosis as there is a lower associated long term anastomotic (false) aneurysm formation than with other sutures.
A buttonhole hernia results when an non-absorbable suture erodes defects through the muscle layer.
96
Which one of the following sutures is non-absorbable?
```
Dexon
Monocryl
PDS
Prolene
Vicryl
```
Monocryl is a synthetic absorbable monofilament vicryl (polyglactin).
Polydioxanone synthetic (PDS) is a synthetic absorbable monofilament suture.
Polyglactin 910 (vicryl / Dexon) is a synthetic absorbable braided suture.
Polypropylene (Prolene) is a synthetic non-absorbable monofilament suture.
97
Which of the following is true regarding fine needle aspiration cytology (FNAC)?
Can distinguish between a follicular adenoma and a follicular carcinoma
Has replaced radionuclide scanning as the procedure of choice in evaluating thyroid nodules
No longer forms part of the triple assessment of a breast lump
Of a branchial cyst produces a serous fluid
Has replaced radionuclide scanning as the procedure of choice in evaluating thyroid nodules
The key factor which distinguishes a follicular adenoma from a carcinoma is invasion of the capsule. An FNAc does not supply this information.
A branchial cyst produces an opalescent fluid containing cholesterol crystals or frank pus.
All patients presenting with a breast lump should have a clinical examination, a radiological examination (ultrasound if under 35 years or a mammogram if over 35 years) and either an FNAC or a biopsy.
The needle is advanced into the lesion and suction applied as the needle is moved in different directions within the mass (stereotactic). In the hands of an experienced cytopathologist the technique is very accurate with a 1% false positive and a 5% false negative rate.
98
Which of the following is correct regarding cytology?
Assessment should not be used on impalpable breast lesion
Evaluation is relatively simple to learn
Refers to the examination of cells and is inherently more reliable than histology
Specimens achieved using fine needle aspirations are usually painless
Specimens are reliable achieved using a TruCut® needle
Histology is the examination of architectural detail and cellular detail at a microscopic level and is therefore more reliable than cytology.
Cytological evaluation requires expert and specialised pathological interpretation.
The procedure can be performed quickly and easily in the out-patients department without the need for local anaesthetic.
A radiologically guided FNA is a useful way of obtaining tissue on an area of microcalcification seen on a mammogram.
A TruCut needle produces a core of tissue which is evaluated histologically.
An FNAC is obtained using a narrow gauge (21G) needle attached to 10 ml syringe under suction.
99
Treatment of hand wounds caused by bites include which one of the following?
A four week course of oral antibiotics for a superficial bite wound
Bite wounds should be closed with interrupted sutures
Bite wounds should be closed with a subcuticular suture
Tetanus toxoid prophylaxis
The use of a tourniquet should be avoided when exploring a septic hand wound
Human and animal bites are usually heavily contaminated and may require debridement, irrigation, immobilisation and systemic antibiotics. Superficial bites often require cleansing and a course of antibiotics. If the patient is not already covered they will require a tetanus booster.
Tourniquets are useful as they produce a bloodless field.
Bite wounds to the hand should never be closed primarily.
Local anaesthetic should not be injected into infected tissue as it has a poor action in the acid medium. Ring block for distal finger injury, or regional anaesthesia may be used rather than a general anaesthetic.
