Download Question 2 : SC

Case 619: Surgical Problems for the Intern - 1
Authors and Affiliations
Peter Devitt
Head, Professorial Surgical Unit
Royal Adelaide Hospital
and
Department of Surgery
University of AdelaideThese MCQs deal with some of the problems that an intern may be faced with
whilst working on a surgical ward.
Case Overview
Learning Objectives
Question 1 : SC
Question Information:
A 63-year-old man develops diarrhoea five days after a laparotomy and small bowel resection for an
enterocutaneous fistula. The antibiotics he has been given since the operation are ceased and over the
next three days the diarrhoea settles and he is making a good postoperative recovery. A stool specimen
sent for analysis shows Clostridium difficile toxin.
Question:
Which one of the following is the most appropriate management plan?
Choice 1: Continue current management plan Score : 1
Choice Feedback:
Correct. Clostridium was first identified as a cause of diarrhoea in 1978 and since then the incidence
and severity of Cl difficile-related diarrhoea and colitis has increased to epidemic proportions. It is now a
major cause of morbidity in hospitalised patients and is perhaps the commonest cause of diarrhoea in
long-stay patients. The emergence of new, resistant strains of C. difficile have added to the morbidity
and healthcare costs associated with this infectious agent.
Many individuals are asymptomatic carriers of C. difficile and as such, probably do not need any
treatment. The risk of treatment is the development of more resistant strains of the organism. This
particular patient has no symptoms now and does not need any more antibiotic therapy.
Choice 2: Metronidazole Score : 0
Choice Feedback:
Incorrect. This might be quite appropriate for a patient who is otherwise well and has a mild episode of
C. difficile-related diarrhoea.
Choice 3: Vacomycin Score : 0
Choice Feedback:
Incorrect. This would be appropriate for a patient with a severe C. difficile-related diarrhoea.
Choice 4: Fidaxomicin Score : 0
Choice Feedback:
Incorrect. This is one of the new macrocyclic antimicrobial agents and has minimal systemic absorption
after oral administration and a narrow spectrum of activity against Gram-positive aerobic and anaerobic
bacteria, including C. difficile.
Choice 5: Fecal microbiota transplantation Score : 0
Choice Feedback:
Whilst this mode of therapy sounds unappetising, it can be an effective way of restoring the normal gut
flora that might have been disrupted through the administration of a broad spectrum antibiotic regimen.
Using naso-duodenal intubation, an infusion of a liquid suspension of intestinal microorganisms from
the stool of a health donor has been shown to be as effective as vancomycin in patients with recurrent
C. difficile-related diarrhoea.
Question 2 : SC
Question Information:
A 30-year-old man is admitted to hospital after a motor vehicle crash in which he sustained a right tibial
fracture. This is treated by internal fixation. One day after surgery he is started on enoxaparin. He
makes satisfactory postoperative progress and two days after admission is starting to mobilise. Two
days later he complains of some right sided chest pain and begins to feel short of breath. Examination
of his chest is normal. His pulse is 105/min and his blood pressure is 140/90mmHg.
Question:
Which one of the following is the most appropriate initial investigation?
Choice 1: CT pulmonary angiogram (CTPA) Score : 0
Choice Feedback:
Incorrect. Whilst this may be the most useful definitive investigation, it is likely to take time to arrange
and in most circumstances it will be much easier to arrange a chest X-ray first. This might show
evidence of chest infection - which must be considered in the differential diagnosis of his respiratory
symptoms.
Choice 2: CT chest Score : 0
Choice Feedback:
Incorrect.
Choice 3: Chest X-ray Score : 1
Choice Feedback:
Correct. This is the simplest investigation to arrange and if it shows evidence of infection - there is no
need to pursue any further imaging. On the other hand, if the chest X-ray is normal, it would be quite
reasonable to think about a pulmonary embolus and consider a CT pulmonary angiogram. Given that
the patient is an otherwise fit, young man and has begun to mobilise rapidly after surgery, the risk of a
venous thromboembolic complication is relatively small.
Choice 4: Duplex ultrasound lower limbs Score : 0
Choice Feedback:
Incorrect.
Choice 5: D-dimer Score : 0
Choice Feedback:
Incorrect.
Question 3 : SC
Question Information:
An otherwise fit 45-year-old man is admitted for a laparoscopic fundoplication for chronic gastrooesophageal reflux disease. Apart from a deep venous thrombosis after a leg injury in his teens, he is in
good health. Mechanical calf compression devices will be used during surgery and other means of
venous thromboprophylaxis must be considered.
Question:
Which one of the following is the most appropriate management?
Choice 1: No other prophylaxis required Score : 0
Choice Feedback:
Incorrect.
Choice 2: Enoxaparin given immediately before surgery and continued until discharge Score : 0
Choice Feedback:
Incorrect.
Choice 3: Enoxaparin given immediately after surgery and continued until discharge Score : 0
Choice Feedback:
Incorrect.
Choice 4: Enoxaparin given immediately after surgery and continued for 10 days Score : 1
Choice Feedback:
Correct. This type of surgery is considered high risk for venous thromboembolism - it is an intraabdominal procedure and may well take more than 45 minutes. The patient is also at increased risk as
he suffered a previous thrombotic event. Some other form of prophylaxis must be used in addition to the
perioperative mechanical devices. The current guidelines suggest a low molecular weight heparin which
should be continued after discharge from hospital for between 7-10 days. Since the patient had not had
a recent or current thrombotic event, there is no need to consider any form of anticoagulation
preoperatively.
Choice 5: Caval filter Score : 0
Choice Feedback:
Incorrect.
Question 4 : SC
Question Information:
A 19-year-old man is injured in motorbike crash in which his right femur is fractured. This is treated by
internal fixation and early mobilisation is encouraged. He makes satisfactory postoperative progress but
on day five complains of sudden on of left sided chest pain which makes him catch his breath. A friction
rub can be heard on the left side on auscultation.
Question:
Which one of the following investigations is most likely to help establish the diagnosis?
Choice 1: Chest X-ray Score : 0
Choice Feedback:
Incorrect.
Choice 2: Electrocardiogram Score : 0
Choice Feedback:
Incorrect.
Choice 3: D-dimer Score : 0
Choice Feedback:
Incorrect.
Choice 4: Arterial blood gas analysis Score : 0
Choice Feedback:
Incorrect.
Choice 5: CT pulmonary angiogram (CTPA) Score : 1
Choice Feedback:
Correct. This patient has almost certainly had a pulmonary embolism. Whilst an ECG and a chest X-ray
will almost certainly be required as part of the diagnostic work-up, it is the CT pulmonary angiogram that
will define the underlying cause of the patients current symptoms.
Question 5 : SC
Question Information:
An otherwise well 68-year-old man is admitted for a total hip replacement. This is being done for
degenerative disease. His past history is unremarkable and he is not on any medications.
Arrangements will be made to minimise his risk of post-operative venous thromboembolic
complications. Apart from the use of graded compression stocking and intra-operative pneumatic calf
compression, other measures must be considered.
Question:
Which one of the following would be most appropriate?
Choice 1: No other measures are necessary Score : 0
Choice Feedback:
Incorrect.
Choice 2: Low molecular weight heparin until discharge Score : 0
Choice Feedback:
Incorrect.
Choice 3: Low molecular weight heparin for one week after discharge Score : 0
Choice Feedback:
Incorrect.
Choice 4: Low molecular weight heparin for four weeks after discharge Score : 1
Choice Feedback:
Correct.
Choice 5: Warfarin for three months after discharge Score : 0
Choice Feedback:
Incorrect.
Question 6 : SC
Question Information:
A 76-year-old man underwent a laparoscopic repair of an incarcerated para-oesophageal hernia. The
procedure was uncomplicated. Twelve hours later he feels well and is sitting up in bed. His blood
pressure is 110/70 mmHg and his urine output since operation has been 100 ml. He has intravenous
isotonic saline running at 80 ml/hr.
Question:
Which one of the following is the most appropriate next step in management?
Choice 1: Continue current management Score : 0
Choice Feedback:
Incorrect.
Choice 2: Intravenous frusemide Score : 0
Choice Feedback:
Incorrect.
Choice 3: One litre isotonic saline over four hours Score : 1
Choice Feedback:
Correct. This man is hypotensive and probably fluid-deplete. Whilst some of his hypotension could be
due to vasodilatation associated with his recent anaesthetic, he has a relatively poor urine output and
this must be corrected.
Choice 4: Dopamine infusion Score : 0
Choice Feedback:
Incorrect.
Choice 5: Noradrenaline infusion Score : 0
Choice Feedback:
Incorrect.
Question 7 : SC
Question Information:
A 72-year-old woman undergoes an emergency laparotomy for perforated diverticular disease. She has
a localised peritonitis and a Hartmann's procedure (sigmoid colectomy, end-colostomy and mucous
fistula) is performed. She makes good progress for the first three days and then on the fourth evening
becomes confused, disoriented and noisy. She is not hypoxic and haematological and biochemical
screens earlier that day showed normal results. A chest X-ray and an ECG are both normal. She has
resumed oral fluids and has required minimal analgesia by this stage.
Question:
Which one of the following is the most appropriate next step in management?
Choice 1: Administer 2mg of intravenous diazepam Score : 0
Choice Feedback:
Incorrect.
Choice 2: Give 10 mg of diazepam orally Score : 0
Choice Feedback:
Incorrect.
Choice 3: Nurse separately in a well-lit room Score : 1
Choice Feedback:
Correct. Postoperative confusion is a common sequelae after surgical events, particularly major
procedures in elderly patients. The first step in the management of such patients is to exclude any
organic and treatable cause for the confusion. This might be a chest infection, drug withdrawal or an
electrolyte disturbance. Once this has been done and any abnormalities corrected, other means of
countering the confusion can be considered. Taking a patient out of their own familiar environment and
routine can be disturbing for them and nocturnal confusion is common. Simple measures such as
providing human contact and lighting the room may be all that is necessary to restore calm. If that does
not work, some form of sedative or hypnotic may be required.
Choice 4: Contact a relative to come in and sit with the patient Score : 0
Choice Feedback:
Incorrect.
Choice 5: Start an intravenous infusion of heminevrin Score : 0
Choice Feedback:
Incorrect.
Question 8 : SC
Question Information:
A 70-year-old man is admitted with a three day history of vomiting. The vomitus is clear-coloured and
contains recognisable particles of food. He has passed very little urine in the preceding 24 hours. He
has suffered with increasing dyspepsia over the last three months. On examination he looks unwell,
with a dry coated tongue and loss of skin turgor. His serum biochemistry shows:
Sodium
126mmol/L (135-145)
Potassium
Chloride
3.0mmol/L (3.8-4.9)
75mmol/L (95-110)
Bicarbonate
Creatinine
Urea
40mmol/L (22-32)
0.18mmol/L (0.06-0.12)
25.1mmol/L (3.0-8.0)
The patient will require intravenous fluids.
Question:
Which one of the following intravenous fluids regimens would be most appropriate?
Choice 1: 2L 0.9% isotonic saline + 30 mmol KCL over four hours Score : 0
Choice Feedback:
Incorrect.
Choice 2: 2L 0.9% isotonic saline + 30 mmol KCl over two hours Score : 0
Choice Feedback:
Incorrect.
Choice 3: 2L 0.9% isotonic saline in two hours Score : 1
Choice Feedback:
Correct. This is a complex problem of presumed chronic peptic ulceration producing gastric outlet
obstruction with persistent vomiting and dehydration. These patients can get a severe metabolic
alkalosis with marked potassium deficiency - but such an extreme situation is not common. The
sequence of events in these patients is starvation and dehydration with a subsequent reduction in the
glomerular filtration rate and a resultant stimulation of aldosterone secretion. This encourages the
reabsorption of sodium in exchange for potassium and hydrogen ions in the distal renal tubule. Isoosmotic reabsorption of sodium in the proximal renal tubule depends on the passive reabsorption of
chloride.
This system would normally lead to conservation of water and sodium by the kidneys and subsequent
excretion of potassium and hydrogen ions into the urine. In cases of severe and prolonged vomiting
there is loss of hydrogen and potassium in the vomitus and an increased loss of potassium in an
increasingly acid urine. This results in severe metabolic alkalosis and hypokalaemia. In an attempt to
counter the effects of the large amounts of hydrogen and potassium ions (with accompanying chloride
ions) lost in the vomitus, the kidneys reabsorb sodium and bicarbonate in the proximal tubules and
more sodium in the distal tubules - doing this in exchange for potassium and hydrogen ions.
With persisting vomiting and the renal efforts to correct the extracellular component biochemical
balance, there will be an extracellular metabolic alkalosis and an intracellular acidosis. The total body
store of potassium becomes depleted as more of the anion is lost in the urine (and the vomitus) and the
kidneys start to excrete more hydrogen ions. This worsens the extracellular metabolic alkalosis with a
paradoxical aciduria. The bottom line is that the patient will require rapid rehydration and replacement of
the lost chloride and potassium ions. Once a diuresis has been established potassium can be given
safely at a rate of 30 mmol/hr.
Choice 4: 4L 0.9% isotonic saline over four hours Score : 0
Choice Feedback:
Incorrect.
Choice 5: 2L 0.9% isotonic saline + 2L 0.5% dextrose over four hours Score : 0
Choice Feedback:
Incorrect.
Question 9 : SC
Question Information:
A previously well 78-year-old man undergoes a laparotomy and oversewing of a perforated peptic ulcer.
His weight is 76 kg. A urinary catheter has been inserted and the patient drains 40ml/hr over the first
three hours after surgery. His serum biochemistry was normal immediately before the operation.
Question:
Which one of the following fluid regimens would be most appropriate for the next 24 hours?
Choice 1: 2L isotonic saline + 1L dextrose 5% + 30 mmol potassium Score : 0
Choice Feedback:
Incorrect.
Choice 2: 1L isotonic saline + 1L dextrose 5% Score : 1
Choice Feedback:
Correct. In terms of maintenance fluid requirements, 2L should meet the 24-hour requirements of an
adult of this body weight. In the immediate postoperative period, there will be increased secretion of
antidiuretic hormone and fluid retention. In a younger, fit patient with assured normal renal function, the
administration of potassium in the immediate postoperative period would be quite safe. However, in the
older patient and those with impaired renal function, it would be prudent to withhold potassium
replacement until a good diuresis has been established.
In reality, this patient will be closely monitored, with serum biochemistry performed shortly after surgery,
and fluid and electrolyte needs titrated to any fluid losses and biochemical disturbances. Third space
losses need to be considered, apart from those from nasogastric and other drains.
Choice 3: 2L isotonic saline + 1L dextrose 5% + 60 mmol potassium Score : 0
Choice Feedback:
Incorrect.
Choice 4: 1L isotonic saline + 1L dextrose 5% + 30 mmol potassium Score : 0
Choice Feedback:
Incorrect.
Choice 5: 3L isotonic saline + 30 mmol potassium Score : 0
Choice Feedback:
Incorrect.
Question 10 : SC
Question Information:
A 57-year-old man is being treated for intestinal obstruction that resulted from an incarcerated inguinal
hernia. Two days after the procedure he has evidence of a paralytic ileus and still requires intravenous
fluids. In the previous 24 hours there has been 1.5L of nasogastric aspirate and 1.2L urine output. His
serum biochemistry shows the electrolyte values are within normal limits.
Question:
Which one of the following would be the most appropriate intravenous fluid regimen for the next 24
hours?
Choice 1: 3L isotonic saline Score : 0
Choice Feedback:
Incorrect.
Choice 2: 2L isotonic saline + 1L dextrose 5% Score : 0
Choice Feedback:
Incorrect.
Choice 3: 1L isotonic saline + 2L dextrose 5% Score : 0
Choice Feedback:
Incorrect.
Choice 4: 3L isotonic saline + 30 mmol potassium Score : 0
Choice Feedback:
Incorrect.
Choice 5: 2L isotonic saline + 1L dextrose 5% + 60 mmol potassium Score : 1
Choice Feedback:
Correct. The normal maintenance fluid for this man will be 2 - 3 L in 24 hours. He will require 100 - 150
mmol of sodium and 60 - 90 mmol of potassium. This can easily be given in the form of 1 L of isotonic
(0.9%) saline (154 mmol sodium), 1 L of dextrose saline, with 30 mmol of KCL added to each litre of
fluid. He will also need some replacement fluid. In this instance 1.5 L of gastric contents have been
aspirated and should be replaced with isotonic saline. Thus he will need at least 3 L of fluid in the next
24 hours. He has a good urine output with normal renal function, so the potassium supplements can be
given safely.
Question 11 : SC
Question Information:
An otherwise well 57-year-old man is admitted with a mild episode of cholecystitis. He has been unwell
for 12 hours with right upper quadrant pain. On examination he looks well and his blood pressure is
130/90 mmHg, pulse rate 90/min and temperature 37.2C. There is mild tenderness in the right upper
quadrant. An ultrasound confirms the presence of gallstones, with minimal thickening of the gallbladder
wall. A cholecystectomy is planned for the day after admission. As part of his management,
consideration must be given to the need for antibiotic prophylaxis.
Question:
Which one of the following would be most appropriate?
Choice 1: No antibiotic prophylaxis is required Score : 0
Choice Feedback:
Incorrect.
Choice 2: Single dose antibiotic at the start of the cholecystectomy Score : 0
Choice Feedback:
Incorrect.
Choice 3: Antibiotics to start on admission and continued until the completion of surgery Score : 1
Choice Feedback:
Correct. The patient has acute cholecystitis. As such, antibiotics will be given on admission. The
standard of care for acute cholecystitis is cholecystectomy during the current admission. Given this
scenario, it is likely that the procedure will be completed laparoscopically and the patient ready for
discharge home the day after cholecystectomy. Whilst the evidence supports the use of prophylactic
antibiotics before and during surgery, there is no hard evidence to support their continued use
afterwards.
Choice 4: Antibiotics to start on admission and to continue until the time of discharge Score : 0
Choice Feedback:
Incorrect.
Choice 5: Antibiotics to start on admission and to continue for five days after surgery Score : 0
Choice Feedback:
Incorrect.
Synopsis