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2022a Worked

Case 1 - 30 minutes

The questions in this case relate to the following paper: R.G Victor et al, (2018) A Cluster-Randomized Trial of Blood-Pressure Reduction in Black Barbershops, New England Journal of Medicine, 37:1291-1301

Part A - 4 minutes

  1. In your own words, outline the researchers’ rationale for undertaking this randomised controlled trial.

Part B - 4 minutes

  1. Interim analyses are often conducted by independent researchers in clinical trials. In this paper two interim analyses were conducted. In your own words outline the reasons for conducting interim analyses in clinical trials including this one.

Part C - 4 minutes

The main findings of the study rela;ng to the primary outcome are outlined in the results section of the paper (PRIMARY OUTCOME) and Figure 2.

  1. In your own words explain the results rela;ng to the primary outcome measure. Your answer should include an interpreta;on of the interven;on effects, rates of progression to cancer, rate difference, confidence intervals and cumulative incidence of progression to cancer.

Part D - 12 minutes

The conclusion in the abstract states that “Among participants with biopsy-proven anal HSIL, the risk of anal cancer was significantly lower with treatment for anal HSIL than with active monitoring.”

  1. What other results from this trial should be considered before recommending a national screening programme for anal cancer for high risk individuals in Aotearoa/ New Zealand?

Part E - 6 minutes

New Zealand has a national AIDS Epidemiology Group to “monitor the epidemic of HIV/AIDS in New Zealand through ongoing surveillance”. 6. 1. Why is it important to undertake surveillance of HIV/AIDS infection in New Zealand? 2. What public health and healthcare services might use the information collected by the AIDS Epidemiology Group?

Case 2 - 30 minutes

Mr David Lewis is a 62 year old NZ-European male who works as an accountant. He visited his general practitioner (GP) today having experienced some chest discomfort after he had to rush to catch a bus. The discomfort lasted about 10 minutes, during which time he felt lightheaded and breathless.

Mr Lewis reports that he has had a couple of similar, but much less severe episodes over the last few months. He had previously put these bouts of being breathless and dizzy down to just being “really unfit”, because they had come on when he was rushing around or carrying something heavy.

His GP considers that his symptoms are likely secondary to cardiac ischaemia.

Part A - 10 minutes

1. Label the structures numbered 1-10 in the image of the heart below. 1. Pulmonary trunk 2. right marginal artery 3. right coronary artey 4. aorta 5. left coronary artery 6. left pulmonary veins 7. left circumfles arteries 8. left anterior descending artery 9. posterior interventricular artery 10. inferior vena cava

The vessel labelled ‘7’ is accompanied by a venous structure.

  1. Where does this venous structure drain into? The great coronary vein drains in the

  2. The autonomic nervous system (ANS) regulates the heart rate. Where do the nerve fibres of the ANS come from and how do each of these systems affect the heart rate?

The origin of the ANS depend on whether the innervation is sympathetic or parasympathetic. Sympathatic will come from the spinal cord, through the sympathetic ganglia and to the visceral ganglia ventral to the abdominal aorta. They will synapse there and go to the heart. The parasympathetic innervation will come from the vagus nerve and go to the heart. parasympathetic slows and sympathetic hastens

  1. Why is cardiac muscle pain often felt in the arm? The receptors that sense pain report to the same parts of the brain that the arm does as so signal recieved from the heart sensory nerves often can be mistakenly attributed to the arm

Part B - 10 minutes

  1. Chest pain arising from myocardial ischaemia (as in Mr. Lewis’ angina) arises from a mismatch between myocardial blood supply (via coronary artery blood flow) and metabolic demands.

    Outline the mechanism(s) by which coronary artery blood flow is normally regulated so that oxygen delivery can match changes in myocardial demand.

incresaes in metabolic use of oxygen lead to increases in metabolic wastes being produced. This in turn causes vasodilation while reduced Vascular resistance and increases bloodflow to the areas of the heart which are highly active

myo genic response high blood pressure vasocontricts as high bp ususally means that the heart doesnt need to do much work low bp vasodilates as the heart needs to do lots of work

nervous stimulation also can increase or decrease vascular diameter through ach and na

  1. An ECG would have been recorded as part of the investigation of Mr. Lewis’ chest pain. This records the electrical activity of the heart which arises from spontaneous “pacemaker” potentials.

    Describe the pathway by which these “pacemaker” potentials spread through the myocardium. You should name the important structures in this pathway and indicate how conduction velocity varies in different parts of the pathway.

    1. SA node origin
    2. internodal pathways 0.5m/s
    3. AV node 0.05m/s
    4. AV bundle 5m/s
    5. R and L bundle branches 5m/s
    6. purkinje fibres 5m/s

Part C - 10 minutes

Mr. Lewis confirms that his chest symptoms presented on exertion. On examination, his BP is raised (160 / 98 mmHg). After careful assessment and exclusion of various differential diagnoses, Mr. Lewis is considered to have stable angina. Mr Lewis is therefore prescribed a sublingual glyceryl trinitrate (GTN) spray, which he is required to take when needed. An ACE inhibitor (cilazapril) is co-prescribed.

  1. Describe the mechanism of action and expected therapeutic effect of GTN in angina. Briefly explain why it is administered through a sub-lingual route.

sublingual is quick, little precautions are needed avoids FPM and is absorped well

GTn is metabolised in the endothelium to NO which is a vasodilator NO activates guanyl cyclase

  1. Why would cilazapril be advocated in angina? Explain your response in terms of the mechanistic impact of this drug on noradrenaline output, and on vascular, and myocardial issues.

Cilarabril inhibit ACE which cleave angiotensin I to angiotensin II which is the main active molecule. ATII causes volume retention, vasocontriction and increases sympathetic signalling. all of these arent great for angina and prescribing this will lead to reduced output, reduced TPR, reduced MABP and reduced sympathetic signalling.

Case 3 - 40 minutes

George Te Rangi is an 87 year old Māori tane who lives at home with his wife. Mr Te Rangi had been experiencing some difficulty in breathing and had lost his appetite, so his wife and his son have encouraged him to see a doctor. He has come into the GP practice today with his son, Joshua.

You are a locum GP and this is your first time meeting Mr Te Rangi. You use the Hui process in your interaction with Mr. Te Rangi and his son.

Part A - 10 minutes

  1. Name and briefly describe the purpose of each of the FOUR (4) phases of the Hui Process.

  2. Describe why it is important to pronounce the names of pa;ents correctly.

Part B - 10 minutes

Mr. Te Rangi’s history and physical examinations findings were suggestive of a pneumonia. He was febrile and his GP arranged for him to be admitted to hospital. Blood and sputum samples were collected.

As part of Mr. Te Rangi’s work up an arterial blood gas (ABG) analysis is done and the results were:

Arterial blood gas (on air)Reference Range
PaO260 mmHg85 - 100 mmHg
PaCO252 mmHg37 - 43 mmHg
pH7.297.35 - 7.45
HCO324 mmol/l24 - 30 mmol/l

The ABG indicates that Mr. Te Rangi is hypoxaemic.

  1. Use the ABG results to identify/rule out the possible cause(s) of his hypoxaemia. Justify your answer.

  2. The examination showed Mr Te Rangi’s respiratory rate to be 26 breaths/minute. Comment on his ventilatory status.

  3. Mr Te Rangi has a haemoglobin concentration of 135 g/L. Estimate his arterial blood oxygen content.

Part C - 10 minutes

  1. Describe the dual blood circulation of the lung.

  2. List the layers that make up the respiratory membrane.

  3. State TWO (2) differences between terminal bronchioles and respiratory bronchioles. goblet cell vs none columnar cells vs coboidal

  4. Label the structures in the following image of a normal chest radiograph.

Part D - 10 minutes

Subsequently, Mr Te Rangi’s fever progressed (39.1˚C), and he additionally developed dysponea and a productive cough with copious yellow sputum. Blood cultures, and a further sputum culture were collected; and a chest radiograph was taken which showed areas of consolidation (shown below).

  1. Briefly describe the type of laboratory tests that would routinely be performed on Mr. Te Rangi’s sputum to determine the infecting microbe. gram stain, culture PCR

  2. Why were blood cultures taken? to see if there was septicaemia or bacteraemia

Laboratory testing revealed an abundance of encapsulated small Gram negative coccobacilli in Mr. Te Rangi’s sputum (shown below). A clinical diagnosis of bronchopneumonia was made.

  1. Which antibiotic would you choose to treat Mr. Te Rangi’s bronchopneumonia ceftriaxone - for H influenza

  2. During therapy, Mr. Te Rangi developed severe antibiotic-associated diarrhoea. Briefly comment on the mechanisms behind this adverse response to the antibiotic therapy. Antibiotics kill off the microbiome which means that unabsorbable sugars and fibre cannot be broken down and leads to osmotic diarrhoea

Case 4 - 20 minutes

Mrs Shepherd is a 63 year old NZ-European female who consults her GP complaining of fatigue and shortness of breath on exertion. Tests show her to be anaemic.

After further investigation she is found to have a carcinoma in her ascending colon. She is admitted to hospital and a right hemicolectomy is performed.

A right hemicolectomy is a procedure that involves removing the bowel from the terminal ileum to the first third of the transverse colon, along with fat and lymph nodes.

Part A - 10 minutes

As part of her investigation she has a double contrast barium enema, a normal example of which is shown here.

  1. What normal anatomical feature of the gastrointestinal tract is demonstrated clearly on this image? What causes this appearance? Colon? its in a funny configuration as the person d

  2. A right hemicolectomy is a procedure that involves removing the bowel from the terminal ileum to the first third of the transverse colon, along with fat and lymph nodes. Which anatomical features demarcate the start and end of the ASCENDING colon? the right colic flexure denotes the end of the ascending colon and the ileocecal valve denotes the beginning of it

  3. The blood supply to the colon is a key component of this surgery. Describe and order the blood supply (both arterial and venous) of the ascending colon which the surgeon will need to be mindful of. ileocecal artery right colic

inferior mesentric vein all needs to be tied off

  1. The lymphatic drainage of the colon is a key component in the staging of the cancer, and the surgeon will take this into account during the surgery. Describe the lymphatic drainage of the ascending colon. it goes pericolic, epicolic, abdominal preaortic than drains out

  2. Which embryological feature facilitates relative ease of mobilising the ascending colon. the mesentry allows the ascending colon to be moved into place and then they fuse

Part B - 10 minutes

  1. What are the normal physiological functions of the large bowel/colon? To store chyme and resorbs salt and water as well as faciliate mass movement

  2. What motility patterns are normally seen in the large bowel/colon? mass movement, where faeces are moved tot he rectum and expelled

  3. What other physiological problem might arise if part of the terminal ileum was also removed? macrocytic anaemia from lack of b12 as b12 is absorbed in the ilieum

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