2016 Paper 3 Flashcards
QUESTION 1
A 35-year-old man presents with gradual onset muscle weakness and polyuria. His blood pressure
is 150/95 mmHg.
Blood tests reveal the following:
Sodium 151mmol/L
Potassium 2.8mmol/L
Glucose 6mmol/L
Total CO2 32mmol/L
a) Name the most likely hormonal abnormality. (2)
○ Aldosterone
○ Conn’s syndrome
○ Aldosterone renin ratio high. Other tests include saline suppression test, ambulatory salt loading test and fludrocortisone suppression test
○ Malignant hypertension from renal vasoconstriction and plasma volume expansion
○ Polyuria secondary to high GFR renin suppression
QUESTION 2
A 20-year-old man on dialysis for chronic renal failure presents with a fractured radius.
Blood tests reveal the following:
Sodium 141mmol/L
Potassium 4.9mmol/L
Urea 22mmol/L
Calcium 2.0mmol/l (normal range 2.2 – 2.7mmol/L)
Phosphate 2.0mmol/l (0.8-1.4mmol/L)
a) What hormonal problem is he likely to be suffering from? (2)
b) Briefly explain the mechanism by which this hormonal problem arises. (3)
c) What abnormality is likely to be seen in his liver function tests? (1)
d) What is the cause of his polyuria? (2)
a) Secondary hyperparathyroidism
b) Total plasma calcium concentration is reduced in CRF. Renal production of
calcitriol (1,25-(OH)2D3) declines, causing decreased intestinal absorption of calcium. Phosphate
excretion is impaired as GFR falls below 20 ml min-1 1.73 m-2 and hyper-phosphataemia develops. As
phosphate levels increase, calcium phosphate is deposited in soft tissues such as skin and blood
vessels further lowering plasma calcium concentration. Hyperphosphataemia also has a negative effect on 1-α-hydroxylase the enzyme responsible for renal calcitriol production. Both
hypocalcaemia and hyperphosphataemia are potent stimuli for parathyroid hormone secretion, leading to secondary hyperparathyroidism. This causes increased osteoclast and osteoblast activity causing osteitis fibrosa cystica. Patients usually tolerate hypocalcaemia remarkably well, as long as oral calcitriol is prescribed and calcium carbonate is used both as an intestinal phosphate binder and a source of calcium.
c) Hepato-renal syndrome
d)
e) Calcitriol and calcium carbonate
QUESTION 3
This is a picture of the screen of a Bispectral index (BIS) monitor
a) What does SR stand for? What does it measure and what is the use/value of this parameter
when monitoring depth of anaesthesia?
b) What does SQI stand for? (1)
c) What does EMG stand for? What does it measure? Is the use/value of this parameter when monitoring depth of anaesthesia?
d) List conditions or drugs that affect accuracy of the BIS monitor when using it for monitoring depth of anaesthesia. (4)
a) Suppression ratio measured as a percentage, represents the proportion of a 63 second time period during which EEG signal was suppressed (isoelectric) and is inversely proportional to BIS value
b) Signal quality index is the quality of the EEG signal
c) Electromyography measures muscle activity, the BIS value becomes less reliable as the amount of muscle activity increased
d)
e
f
QUESTION 4
A 5-week-old boy has been vomiting for a week. Clinically he is severely dehydrated.
Abdominal examination shows a small mass in the upper abdomen.
Results of blood tests:
Sodium 130mmol/L
Potassium 2.8mmol/L
Chloride 82mmol/L
Bicarbonate 32mmol/L
Urine dip-test: acidic
a) Why is he hypochloraemic? (1)
b) Write short notes on why his serum bicarbonate is raised? (5)
c) List 4 possible reasons as to why his urine is acidic. (4)
Vomiting HCL acid
Normally, as the gastric acid passes into the duodenum, it is
neutralised by pancreatic HCO3,If vomiting occurs with an intact communication
between stomach and duodenum, both H+ and HCO3 are lost with a neutral effect on acid/base balance. However, in pyloric stenosis there is loss of H+ and a consequent net increase in plasma HCO3
– concentration.Metabolic alkalosis secondary to duodenal bicarbonate secretion
Hypokalaemia impairs Na/k atpas therefore excretion of hydrogen ions in exchange for Na occurs resulting in acid urine
Question 5
A 21-year- old female has the following liver function tests:
Total Bilirubin 6ɥmol/L (5-21)
Conjugated bilirubin 2 (0-3) ɥmol/L
Alanine transaminase 18 (7-35) U/L
Aspartate Tranasaminase (13-35) 16 U/L
Alkaline phosphatase 84 (42-98) IU/L
HBsAg +
HBcAb +
HBeAg –
a) What is the significance of the negative HBeAg test in this patient?
b) What two possible types of hepatitis does this patient have? (2)
c) What blood test is required to differentiate between these two types of hepatitis? (2)
d) Is this patient an infective risk for operating room personnel? Briefly explain your answer. (2)
e) Provide 2 long-term complications of this condition for this patient. (2)
a) level of HBeAg Correlate with the infectivity and viral replication while Anti HBeAg presence indicate low activity and infectivity.
b) acute or chronic infection
c) Anti HBcAg IgM positive in acute and negative in chronic infection
d) Yes he has acute hepatitis as indicated by the presence of HBsAg antigen and igm + HBcAg
e) Risk of hepatocellular carcinoma and cirrhosis
QUESTION 6
A patient in ICU is hypotensive. You decide to use the transthoracic echo to investigate the cause
and guide management.
a) Name the specific view.
b) Label from A to F.
c) What measurement can you obtain from the above view that is needed in the calculation of cardiac output?
d) Using the given measurements, Aorta diameter 2 cm; VTI 14 cm; EF 68%; heart rate 51 beats per minute supply the formula and calculate cardiac output. (5)
a) Parasternal long axis view
b) a= RV b= IVS C= AV D=LV E= RA F= Ascending aorta
c) VTI of LV, LVOT diameter = radius
d)
e)
QUESTION 7
Serial thromboelastograms (TEG’s) were done on a septic ICU patient.
With respect to each of the diagrams
a) What coagulation abnormality does this TEG show? (3)
b) Briefly explain the underlying pathophysiology at this stage of the coagulation disorder. (3)
c) State your specific management at this stage of this disease process. (4)
QUESTION 8
Pacemaker – A 75-year-old man with a known history of cardiac disease presents for an elective
inguinal hernia repair. On enquiry he confirms recent onset of syncope. Below is his admission ECG
(EKG)
a) Describe the rhythm and conduction abnormalities in this ECG. (4)
b) Based on this EKG, give the possible reason for his new onset syncope.
How would you manage this problem? (5
a) Sinus rhythm, irregular rhythm with p waves and qrs complexes asynchronous, Atrial sensing intact but no consistent ventricular capture
b) Complete heart block with pacemaker failure.
c) cardiology referral, temporal external or iv pacing, bloods for u&e exclude electrolyte imbalances
QUESTION 9
A 78-year-old woman is on the orthopaedic list for repair of a femur fracture. She reportedly became
dizzy and fell, fracturing her right hip. She also reports yellow halos around lights. Her post admission ECG (EKG) is as follows
a) Analyse the ECG with particular reference to any abnormalities. (4)
b) What are the likely pathophysiological causes for the ECG findings? (2)
c) What is the risk of proceeding with surgery under general anaesthesia considering the above
ECG?
d) You have excluded physiological causes for the abnormal ECG. How would you further address the problem? (3)
a) Sinus rhythm rate of91/min normal axis, no apparent chamber enlargement. Left ventricular strain pattern as marked by st depression and t wave inversion in l1,2 v 3456 -lateral and inferior leads
b) supply demand mismatch:
c) progression to stemi
d) coronary artery disease,
QUESTION 10
A 63-year-old female presented for a staging laparotomy. The following data was recorded on a
minimally - invasive cardiac output monitor during her operation.
a) What is your interpretation of this data? (2)
b) What are the reference and action guidelines when using stroke volume variation to evaluate volume responsiveness?
c) List 3 prerequisites that need to be fulfilled when using stroke volume variation to evaluate
volume responsiveness? (3)
d) List 3 limitations when using stroke volume variation to evaluate volume responsiveness. (3)
a) Patient initially had normal cardiac index and svv which declined rapidly then increased again to normal levels. This may have been secondary to acute blood Los with subsequent correct or use of vasoactive agen5s
b)
• Stroke volume variation is a functional hemodynamic variable that estimates fluid responsiveness in ventilated patients with low preload and thus also aids in the guidance of fluid resuscitation therapies.
• The concept is that cyclic changes in the intrathoracic pressure during positive pressure ventilation induce changes in SV and pulse pressure variation (PPV) secondary to multiple mechanisms.
• SVV represents the variability of SV during a respiratory cycle, in which it
increases during inspiration and decreases during expiration (the opposite occurs during spontaneous ventilation).
• It is calculated by the following equation: SV max – SV min/SV mean.
• A result of more than 13% (10–15%) suggests potential preload responsiveness.
c)
• Intact chest wall
• Muscle relaxation
• intra aortic balloon pump
• VAD
• Spontaneous breathing
• High PEEP
• Severe obesity
• Medication
•
d)
e
QUESTION 11
A patient is hypotensive in ICU after coronary artery bypass surgery. The attending doctor
administers 50µg of phenylephrine (PE) intravenously to the patient. Haemodynamic measurements
are taken before and after the phenylephrine bolus.
Draw two superimposed, labelled, pressure-volume loops which depict the haemodynamics
before and after the phenylephrine bolus. Include representations of the endsystolic elastance
(Ees) and effective arterial elastance (Ea) lines on your diagrams.
b) Provide a brief clinical interpretation of the data. (4)
Left ventricular pressure-volume (PV) loops showing the effects of contractility changes on Ees and afterload variations in Ea. (A) Cardiac contractility was increased with dobutamine and decreased with esmolol. The slope of the end-systolic PV relation (ESPVR) defines the end-systolic elastance (Ees, dashed colored lines) and the contractility performance at each stage. (B) Afterload was increased with phenylephrine and decreased with sodium nitroprusside. The lines connecting the end-diastolic volume and end-systolic pressure describes the effective arterial elastance at each stage (Ea, dotted colored lines).
QUESTION 12
Read the following abstract from a recent publication and answer the questions below.
a) Explain what the advantage of a crossover trial is.
b) 55 Why are calculation of confidence intervals, rather than “p” values, needed to prove noninferiority
Regarding the sentence in the results: “Compared to black coffee, the gastric volume for 20% milk was significantly decreased with a difference of -10.0ml (95% confidence interval, -18.2, -1.8), and for 50% milk it was insignificantly decreased, -7.2ml (95% confidence interval, -17.4, +2.9)”, does “insignificantly decreased” refer to statistical significance, clinical significance, or possibly to both? Explain clearly
With the information available in this abstract, would you change your practice i.e. let patients have milk in their coffee 2 hours before surgery? List 3 reasons.
a) Above is an ultrasound image in the transverse plane just caudal to the inguinal ligament showing normal anatomy. Draw a diagram of this image indicating the important venous, neural and fascial structures.
57 What is the importance of identifying the fascia layers when doing nerve blocks in this region? (2)
List six methods to prevent nerve injury during nerve blocks.
QUESTION 14 58
a) Draw and annotate a normal trans-gastric mid-papillary short-axis echocardiography view. Also mark the areas of muscle supplied by the 3 main coronary arteries. (5)
b) What is the best indicator of global left ventricular function that may be calculated from this view and how is it calculated?
c) Provide 2 limitations of this calculation as index of global left ventricular function.
d) Draw another image of the same view in a patient with acute massive pulmonary embolism. (1)
a)
b) fractional shortning
c)
d) PE will cause increase pulmonary artery pressures with right ventricular dilation from the back pressure. This will result in D shaped LV as the IVS pushes toward it
QUESTION 15 60
a) Give the formula used to calculate the A-a (Alveolar-arterial) gradient. (2) - b) c)
b) What are the shortcomings of the A-a gradient? (2)
c) For each of the following cases, calculate the A-a gradient and the PaO2/FiO2 ratio. Using the result of your calculation, give ONE likely mechanism for the hypoxemia and the appropriate treatment thereof.
i) Following general anaesthetic. PaO2 = 7,9 kPa PaCO2 = 9,6 kPa FiO2 = 21% (3) -
ii) Patient with abdominal sepsis. PaO2 = 7,5 kPa PaCO2 = 5,4 kPa FiO2 = 21%
a) (Pbar-pH20 )FIO2- Pco2/0.8- PaO2
b) Gradient varies with age and FiO2:
FiO2 0.21 – 7 mmHg in young, 14 mmHg in elderly
FiO2 1.0 – 31 mmHg in young, 56 mmHg in elderly
• For every decade a person has lived, their A–a gradient is expected to increase by 1 mmHg – a conservative estimate of normal A–a gradient is < [age in years/4] + 4.
• an exaggerated FiO2 dependence in intrapulmonary shunt (PAO2 vs PAO2/PaO2 difference diagram with regard to increasing percentageof shunt) and even more so in V/Q mismatch.
c)
d)
QUESTION 16 62 A 48-year-old hypertensive man with a 3 year history of myasthenia gravis. He is 176cm tall and weighs 137kg. He has a 20 pack year history of smoking. His daily medication includes pyridostigmine (Mestinon) 60mg, prednisone 40mg. A baseline arterial blood gas (ABG) on room air performed usigna co-oximiter reveals the following pH: 7.43 (normal 7.35-7.45) pCO2: 6.8 kPa (normal 4.67-6.00) pO2: 10.64 (normal 10.67-13.33 kPa) SO2: 94% Hb: 13.3g/dL COHb: 5% (normal 0.5-1.5) BE: +4.53 mmol/L HCO3־ ST : 32.0 mmol/L
a) Calculate BMI and categorise this patient according to the standard WHO BMI classification table.
b) Interpret the arterial blood gas.
c) List 3 possible reasons for hypercarbia: COAD, Obesity, OSA, Myasthenia, Medications. (
Pulse oximetry in the theatre on room air indicates saturation to be 99%. Explain why this may be different from co-oximiter measured saturation.
