SBA SCE style Questions Flashcards
A 22 year old with no prior medical history arrives in ED with a low GCS. His friends state that he was complaining of headaches, nausea and dizziness prior to the drowsiness. They deny any alcohol or illicit drug use. They state that a new boiler was installed in the patient’s flat last week, and he was concerned that the workman did not seem competent. The landlord had declined to come and check the work. Observations: T 37.3, P 95, BP 110/70, Sats 98% on air, GCS 11 (E3 V3 M5)
What is the single most appropriate initial management plan?
A. Call the intensive care department to request intubation
B. Controlled oxygen with target sats 94-98%
C. High-flow oxygen 15L through a reservoir mask
D. Initiate non-invasive ventilation
E. Venturi mask 40% flow
C. High flow oxygen 15L through a reservoir bag
A normal/high oximetry reading should be disregarded in suspected CO poisining as saturation monitors cannot differentiate between COHb & HbO2, owing to their similar absorbances. This is a rare example of when a reservoir mask at 15 L/min should be used. COHb levels should be checked. These can be slightly high in smokers, but a significantly raised level would be expected in cases of CO poisoning (>3% in non-smokers, >10% in smokers). Levels correlate poorly with clinical severity. Oxygen hastens the dissociation of CO from COHb, turning it back into Hb. Hyperbaric oxygen is also a useful treatment where available. NIV & intubation are not usually required. Prevention of CO poisoning can be simply achieved by the maintenance of boilers, generators & stoves, & the use of CO detectors. In England landlords only have to fit a CO alarm in a room with a solid fuel burning appliance.
A 42 year old woman wants to stop smoking. She has tried on two previous occasions, using nicotine replacement therapy in the form of patches. She has recently had a health scare, and is very keen to successfully quit this time around. She asks you for advice about the most effective ways to stop smoking.
What is the single most accurate statement about smoking cessation interventions?
A. A combination of psychological support and pharmacological treatment is no more successful than pharmacological treatment alone
B. E-cigarettes have the same efficacy in achieving abstinence from tobacco smoking as other smoking cessation interventions
C. Patients with COPD are as likely to quit as smokers without COPD following smoking cessation interventions
D. Smoking cessation interventions lead to a quit rate of 50% at 1 year
E. Varenicline is more likely to be effective than psychological support alone
E. Varenicline is more likely to be effective than psychological support alone.
In a double blind placebo controlled RCT in patients with COPD from abstinence at 9-12wks was 42% with varenicline, compared to 8.8% in the placebo arm (https://t.co/TUPBDz982q).
A meta-analysis from 2006 in concluded varenicline > bupropin > nicotine replacement in supporting smokers to quit at 3 months. Indirect comparisons were used (https://t.co/kRMeNTsS0P).
In a pragmatic RCT people were randomised to nicotine e-cigarettes, placebo e-cigarettes or nicotine patches. E-cigarettes had similar rates of abstinence to patches, but quit rates were low in this study (https://t.co/clnEnVBa1D).
In a 2019 UK study e-cigarettes were significantly more effective than NRT. 1yr quit rates were 18% for e-cigarettes, 9.9% for NRT. They were also shown to be cost-effective (https://t.co/lZApHsvsSf).
A 42 year old woman is awaiting a cholecystectomy, and has spirometry as part of a pre-op assessment.
Spirometry shows:
FEV1 0.95L (36% predicted – SR –2.11)
FVC 2.15 (70% predicted – SR –1.76)
Ratio 44%
What is the single best description of these results?
A. Consistent with obesity
B. Mild restrictive defect
C. Poor effort, therefore un-interpretable
D. Severe obstructive defect
E. Within normal limits
D. Severe obstructive defect
In this example FEV1 is very low, whereas the FVC is almost within normal range. The ratio is 0.44 which shows severe obstruction, as per GOLD guidelines.
GOLD 1 mild, FEV1 >80% predicted
GOLD 2 moderate, 50% < FEV1 >80% predicted
GOLD 3 severe, 30% <FEV1>50% predicted
GOLD 4 very severe, <30% predicted</FEV1>
SR (standard residuals) are very useful. For a conventional 90% lower confidence limit, an SR value more negative than -1.645 means the index is abnormal.
A restrictive defect, as would be expected in obesity, would have a FEV1/FVC of >0.7.
We can’t fully interpret these results - we’d want to see a flow volume loop, a TLCO & a slow VC. There could well be a mixed defect. But from the info given the best answer is severe obstruction
A patient with COPD wishes to fly to see relatives in Tokyo, Japan. A direct flight is 11hr 50min. They ask whether it is safe for them to fly and whether they will need to arrange in-flight oxygen. Their COPD symptoms are currently stable. They take a combination LABA/LAMA inhaler and carbocisteine. They have never been admitted to ICU but had ward based NIV for hypercapnic respiratory failure 6 months ago due to influenza A leading to a severe exacerbation. On outpatient testing pCO2 had normalised by 6 weeks.
Which one of these suggests the patient is at risk of in-flight hypoxia, and therefore needs to undergo a hypoxic challenge test?
A. Exacerbation within the last 3 months
B. Hospital admission within the last 6 months
C. MRC breathlessness score of 2
D. Resting Spo2 <98%
E. Six minute walk test desaturation to <84%
E. Six minute walk test desaturation to <85%
Patients with COPD who should undergo hypoxic challenge testing include: resting SpO2 ≤95%; MRC score 3 or greater; and desaturation to <84% on 6MWT or SWT in whom there are concerns about hypercapnia.
BTS guidelines on air travel: https://t.co/jH4GCrchFk
European & N American regulations limit max cabin altitude to 2438m (8000 ft) under normal operating conditions. This is based on the oxyhaemoglobin dissociation curve - up to this level SaO2 remain >90% in the average healthy individual. In a study of 1260 healthy volunteers, no significant changes occurred in (SpO2) during a simulated 8-hour flight at cabin altitudes up to 2438m (8000 ft). However, if cabin altitude exceeds 3048m (10000 ft) SaO2 falls to∼89% (https://t.co/X8d6oLx5nf).
The hypoxic challenge test uses an inspired gas mixture containing 15% oxygen, which gives similar PO2 to breathing air at the max allowable cabin pressure altitude. The patient breathes the hypoxic gas mixture for 20min, or until SpO2 reaches 85%.
When interpreting the hypoxic challenge test
PaO2 ≥6.6kPa (≥50mm Hg) or SpO2 ≥85%: in-flight oxygen NOT required.
PaO2 <6.6kPa (<50mm Hg) or SpO2 <85%: in-flight oxygen recommended
A 21 year old patient with Cystic Fibrosis is being assessed for eligibility for CTFR modulators. They have one copy of the F508del mutation and another previously undescribed residual function mutation.
Which ONE of the following CFTR modulators is the single best treatment option?
A. Kaftrio
B. Kalydeco
C. Lumacaftor
D. Orkambi
E. Symkevi
E. Kaftrio
There are now several CFTR modulators available, in three main classes: potentiators, correctors and premature stop codon suppressors. Kaftrio is triple combination therapy, ivacaftor, tezacaftor and elexacaftor (Trikafta in the USA). It’s available for patients with two copies of the F508del mutation or one copy of F508del and any other mutation.
There are 6 classes of CFTR mutation. Class I & II CFTR mutations are characterised by a reduction in the quantity of expressed CFTR protein. This ERS review is a great read: https://t.co/K3Eisej6qh.
Class I mutations can result from nonsense & frame-shift mutations, as well as mRNA splicing defects. E.g. G542X is a nonsense or stop mutation. Introduction of a premature stop codon leads to production of truncated CFTR protein. Class II mutations, including F508del, have folding or maturation defects, which can result in premature CFTR degradation.
You are in the regional respiratory failure unit for a placement. You spend time with the specialist respiratory physiotherapist and comment on the fact that there are a significant number of young adults treated by the service. You discuss causes of respiratory failure in young people.
Which ONE of the following is at highest risk of respiratory decompensation by adolescence?
A. Duchenne muscular dystrophy
B. Limb girdle muscular dystrophy
C. McArdle disease
D. MELAS (Mitochondrial Encephalomyopathy with Lactic Acidosis and Stroke-like episodes)
E. Pompe disease
A. Duchenne Muscular Dystrophy
Duchenne muscular dystrophy is one of the most frequent genetic conditions affecting approx 1/ 3500 male births worldwide (it is X-linked). It leads to progressive weakness & respiratory failure by adolescence.
Pompe disease and McArdle disease are glycogen storage disorders, and limb girdle muscular dystrophy is a sarcoglycanopathy, all of which are highly variable. MELAS (Mitochondrial Encephalomyopathy With Lactic Acidosis and Stroke-Like Episodes) may also progress to respiratory failure, but this is typically in adulthood.
You are teaching final year medical students about normal thoracic physiology and how it is relevant to respiratory disease. During a discussion on pneumothorax and chest drains, a students asks you to explain intrapleural pressure changes.
Which ONE of the following is the most accurate estimation of intrapleural pressure at end expiration?
A. -8kPa
B. -4kPa
C. 0kPa
D. 4kPa
E. 8kPa
B -4kPa
Intrapleural pressure depends on the ventilation phase, atmospheric pressure, and the volume of the intrapleural cavity. At end expiration there is a negative intrapleural pressure of -4kPa below atmospheric pressure. This is due to the recoil of the chest and lungs away from each other.
You are asked by your consultant to do a presentation at your weekly departmental educational meeting. Your heart sinks when they tell you that the theme is ‘tumours of the mediastinum’.
Which ONE of the following is the single most common anterior mediastinal tumour ?
A. Lymphangioma
B. Parathyroid adenoma
C. Seminoma
D. Teratoma
E. Thymoma
D. Thymoma
The mediastinum is an anatomical space between the lungs that houses: thymus, heart, large blood vessels, lymph nodes, nerves, & parts of the oesophagus & trachea. Mediastinal boundaries are anteriorly: sternum; posteriorly: thoracic vertebrae; superiorly: thoracic inlet; inferiorly: diaphragm; laterally: pericardial & mediastinal pleurae. It has anterior, middle, & posterior compartments.
Mediastinal masses range from benign to malignant. 50% of mediastinal masses are in the anterior compartment, the most common of which are: thymoma, teratoma, thyroid goitre & lymphoma.
Thymomas represent approximately 20% of anterior mediastinal tumours. Teratomas and seminomas are both germ cell tumours and together account for approximately 15% of tumours. Lymphangiomas and parathyroid adenomas are rare.
Thymomas typically occur in adults >40yrs, & affect males & females equally. 30% - 50% of patients with a thymoma have myasthenia gravis, whereas 10–15% of patients with myasthenia gravis have a thymoma
A 55 year old presented with uveitis and fatigue. A CT chest showed bilateral hilar lymphadenopathy. EBUS-TBNA showed non-caseating granulomas. His pulmonary function tests were normal. Topical steroids were given for his uveitis. At follow-up he complains of episodes of palpitations. He has had one episode where he briefly lost consciousness but he did not seek medical attention. He feels well today.
Which ONE of the following is the most appropriate action?
A. Cardiac MRI
B. Coronary angiogram
C. Reassure and continue 6 monthly review
D. Refer for cardiac biopsy
E. Start prednisolone 60mg OD
A. Cardiac MRI
Cardiac sarcoidosis can lead to arrhythmias including complete heart block and cardiac failure. An ECG and echocardiogram would be useful initial tests, along with a Holter monitor but would not be diagnostic. Biopsy would provide a definitive diagnosis but is invasive and has significant risks. It would not be justified prior to non-invasive options. Diagnosis is often achieved by cardiac MRI so this is the next step.
The incidence of cardiac #sarcoidosis has been increasingly recognised, with a large 25-year Finnish cohort study reporting an exponential increase from 1988 to 2012, with a prevalence of 2.2 per 100,000 adults (https://t.co/VdBS1woHte).
Among patients with systemic #sarcoidosis ~5% will have clinically manifest cardiac sarcoidosis, but 25% may have evidence of cardiac involvement on autopsy or imaging studies.
A 58 year old woman is seen in clinic with breathlessness. She is a non-smoker but had significant second hand smoke exposure from age 18-40. She has had 2 pneumothoraces and required VATS pleurodesis with apical bullectomy 2 years ago. Her daughter recently had a pneumothorax and the patient is concerned that her lung condition is heritable. Her CT scan shows panlobular emphysema with basal predominance.
Which ONE of the following is the most useful investigation?
A. Alpha-1-antitrypsin phenotype (AAT)
B. Beryllium Lymphocyte Proliferation Test (BeLPT)
C. Human Leukocyte Antigen B27 (HLA-B27)
D. Serum Angiotensin Converting Enzyme (sACE)
E. Serum Vascular Endothelial Growth Factor- D (VEGF-D)
A. Alpha-1-antitrypsin phenotype (AAT)
Alpha-1-antitrypsin (AAT) deficiency is a genetic disorder that produces inactive/defective AAT due to mutations in the SERPINA1 gene. The disease is associated with decreased activity of AAT in the lungs and deposition of excessive defective AAT protein in the liver. Approx 1–5% of patients with diagnosed COPD are estimated to have AAT deficiency.
AAT deficiency can present with liver dysfunction from childhood & with COPD from 30 years. People with AAT deficiency are also at increased risk for panniculitis (migratory, inflammatory, tender skin nodules which may ulcerate).
Phenotypic expression varies within & between families with AAT deficiency. In adults, smoking is the major factor in accelerating the development of COPD; non-smokers may have a normal life span, but can also develop lung &/or liver disease.
Diagnosis of AAT deficiency is through demonstration of low serum concentration of AAT & protease inhibitor (PI) typing. The most common (normal) allele is PIM, the most common pathogenic allele is PIZ.
Most patients with AAT deficiency have panlobular emphysema, typically with basal predominance. However patients with a less severe PI allele combination (i.e. PISZ) have more apical involvement than those with the most severe (PIZZ)
A patient states that since moving from Norfolk to London their asthma has been much worse. They have more daily symptoms and exacerbations, and it does not seem to be seasonal. They are concerned that the higher exposure to air pollution is to blame and ask for your advice on what to do to reduce exposure.
Which ONE of the following is the most accurate statement?
A. Cloth face masks remove >20% particulate matter
B. Driving to work with the windows closed will reduce your exposure compared to walking or cycling
C. Segregated and on-road bike lanes have the same level of pollution
D. The protective effects of exercise outweigh risks from exposure
E. Using an Ecodesign woodburning stove to heat your home will avoid indoor pollution
D. The protective effects of exercise outweigh risks from exposure
Air Pollution is particles & gases harmful to human health. We particularly worry about PM2.5 NO2 & ground level O3. Air Pollution affects every organ & all ages. It affects everyone, but not equally, causing health inequalities. Air Pollution from burning Fossil Fuels like coal & diesel is responsible for about 1 in 5 deaths worldwide.
Clinicians must be able to advise patients on how to reduce their exposure and contribution to air pollution. Although patients with Respiratory disease should be advised to avoid strenuous exercise at high risk times of high pollution days, overall exercise has so many health benefits that these outweigh the risks even for those living in high pollution areas.
A 51 year old man is referred to the sleep clinic. He has recently started a new relationship and his partner has noticed loud snoring, and witnessed apnoeas. He is also sleepy during the day. His STOP BANG score is 5. His Epworth Sleepiness Scale is 16/24. His BMI is 34kg/m^2. An overnight oximetry is arranged. The oximetry trace shows a saw tooth pattern of desaturations with associated rises in pulse rate.
Which ONE of the following is the most appropriate next step in management?
A. Advice to lose weight
B. Mandibular advancement device
C. Refer for uvulopalatoplasty
D. Trial of CPAP
E. Trial of NIV
D. Trial of CPAP
CPAP is the first-line treatment option for patients with moderate to severe OSAS. Weight loss, in some cases, can reduce the need for CPAP but will take time. This patient is symptomatic and the severity of OSAS warrants CPAP as first-line treatment. Snoring or mild OSA could be treated by mandibular advancement splint, but not severe OSA with significant sleepiness as in this case. There is no evidence of a need for NIV, but it would be useful to see an ABG and TCO2 trace.
A 48 year old who had a bilateral lung transplant 6 years ago for emphysema associated with inhaled drug use in his youth, has progressive breathlessness. He has no chest pain, minimal sputum production, no fevers and weight has remained stable. Serial spirometry over the last 4 months has shown a decline, falling more rapidly in the last 2 weeks. FEV1 has fallen from 3.6L to 2.3L. FVC has fallen from 4.4L to 4.0L.
What is the single most likely cause of lung function decline?
A. Acute rejection
B. Chronic Lung Allograft Dysfunction (CLAD)
C. Cytomegalovirus reactivation
D. Post-transplant Lymphoproliferative Disease (PTLD)
E. Restrictive allograft syndrome (RAS)
B. Chronic Lung Allograft Dysfunction (CLAD)
These terms may be unfamiliar but you can arrive at the correct answer by a process of elimination. The timeline is not right for acute rejection or CMV reactivation. Symptoms other than progressive breathlessness would also be expected. PTLD is the most common cancer in the first year post-transplant but remains a risk later. Late PTLD is more commonly extra-thoracic, and even if thoracic would be unlikely to present with breathlessness. This leaves CLAD or RAS.
The lung function results show an obstructive pattern. RAS is a subtype of CLAD but would have a restrictive pattern on spirometry.
Rejection can happen at any time after lung transplantation. Around 1/3 of patients will develop ‘acute rejection’ in the 1st year.
This is often an immune reaction to the donor tissue, & may be T-cell mediated &/or
antibody-mediated. Lung transplant recipients with acute rejection may be asymptomatic or may have non-specific symptoms eg dyspnea, cough, sputum production, & low-grade fever. Severity is graded pathologically. It’s essential to detect acute cellular rejection in lung transplant recipients as it is a major risk for chronic rejection. Acute cellular rejection grades A2 or higher require treatment, generally with pulsed IVMP.
You attend a chronic breathlessness specialist service and discuss the complex nature of the sensation, including physiological, psychosocial, social and environmental factors. Your supervisor asks about your knowledge of neural pathways implicated in breathlessness.
Which one of the following areas of the brain is most associated with the sensation of breathlessness?
A. Cerebellar vermis
B. Hippocampus
C. Insular cortex
D. Pineal gland
E. Prefrontal Cortex
C. Insular cortex
Breathlessness is a complex symptom with many contributors. These include: chest wall mechanoreceptors, chemoreceptors, sensory afferents in the airways & parenchyma, (RARs & SARs), vagal C fibres & central nervous system pathways
Research using functional neuroimaging (fMRI) has identified a consistent set of brain areas that are associated with breathlessness, in both patients and in experimentally induced air hunger. These areas include the insular cortex, cingulate and sensory cortices, the amygdala and the periaqueductal gray matter. Breathlessness, just like pain, is not a purely somatic (physical) phenomenon, but arises from inferences made by the brain’s integration of expectations, emotions and
sensory inputs.
A new biomarker blood test, LYCA1, has been developed to identify Idiopathic Pulmonary Fibrosis (IPF) in the hope of predicting who will respond to anti-fibrotic medications nintadenib & pirfenidone. In a study of 100 patients with probable UIP pattern or indeterminate for UIP pattern on CT scan 65 patients had positive LYCA1 tests, and 50 of those had IPF on biopsy. There were also 20 patients who had IPF on biopsy but who had negative LYCA1 blood tests.
Which one of the following is most accurate in relation to the LYCA1 test?
A. The false positive rate was 30%
B. The true negative rate was 20%
C. The prevalence of IPF in this study population was 65%
D. The sensitivity was 71%
E. The specificity was 56%
D. The sensitivity was 71%
The best way to approach this sort of question is to construct a 2x2 table. You can then answer questions on true and false positive/negative rates, sensitivity, specificity, positive predictive value and negative predictive value.
The study had 100 participants, and 70 (50+20) of them had IPF according to the gold standard test of lung biopsy. The prevalence was therefore 70%.
65 patients had a positive LYCA1 test & 50 of those had IPF on biopsy, so 15 had a false positive test. Sensitivity is the % of people who test positive, among those who have the disease: 50/(50+20) = 71%. A sensitive test helps rule out a disease when the test is negative - if LYCA1 is negative we can be quite confident they don’t have IPF. The specificity of a test is the % of people who test negative among all those who do not have that disease: 15/(15+15) =50%. A specific test helps rule a disease in when positive - if LYCA1 is positive we can’t be very confident they have IPF. The positive predictive value of the LYCA1 test is the probability that following a positive test result, that individual will truly have IPF: 50/(50+15)=77%. The negative predictive value of the LYCA1 test is the probability that following a negative test result, that individual will truly not have IPF: 15/(15+20)=43%.
The PPV & NPV of a test are affected by prevalence. As prevalence increases, PPV also increases but NPV decreases. Similarly, as prevalence decreases PPV decreases while NPV increases.
A 24 year old has recurrent community acquired pneumonia. He also has a history of otitis media and immune thrombocytopenia. There is no relevant family history. A CT scan reveals mild lower lobe bronchiectasis. Blood tests show Hb 130g/dL, WCC 8.3x10^9/L, MCV 98fL, Plt 75x10^9/L, IgG 340 (600-1600mg/dL), IgA 75 (80-300mg/dL), IgM 40 (40-250mg/dL). HIV, Hepatitis B and C are negative. Tetanus antibody titre 0.005 (0.01-0.15 IU/mL), HiB antibody titre 0.2 (>1.0mg/L).
Which of the following is the single most likely diagnosis?
A. Common Variable Immunodeficiency
B. Pearson Syndrome
C. Severe Combined Immunodeficiency
D. Selective IgA deficiency
E. X-linked agammaglobulinaemia
A. Common Variable Immunodeficiency
This patient has typical features of CVID, with recurrent bacterial infections including pneumonia and otitis media, chronic lung disease in the form of bronchiectasis, and an autoimmune condition (present in 25% cases), in this case immune thrombocytopenia. Blood tests show low levels of immunoglobulin G (IgG) and IgA, as well as IgM in some patients. IgG levels are generally <400, with more severe phenotypes <100mg/dL. There is also a lack of antibody response to vaccinations. The other answers are all other immunodeficiency syndromes, which may have recurrent infections, but not these blood results, except Pearson syndrome, a rare mitochondrial disorder leading to bone marrow failure.
CVID is a primary immune deficiency disease caused by a variety of different genetic abnormalities that result in disorders of B-cell differentiation & maturation with dysfunctional antibody production. CVID affects 1/25,000 - 50,000 varying across populations/regions. Most people present in their 20-30s but it can affect any age. Late diagnosis is common. Most cases arise randomly, but 5% - 25% cases are inherited (AR or AD). Interestingly the gut #microbiome has been suggested as a contributor to CVID as a mechanism through which epigenetic factors influence the interplay of genes, environmental factors, & dysregulation of immune cells. Clinical features of CVID are recurrent bacterial infections (less so viruses), particularly chest, sinonasal, ears. GI infection/ inflammation is also common. 20% have an autoimmune cndition eg ITP, AIHA. Splenomegaly & lymphadenopathy occur. Some people with CVID are more prone to developing some cancers eg lymphoma, skin cancer & gastric cancer (almost 50x risk in patients with CVID). Lung involvement in CVID is recognised, including bronchiectasis, OP & ILD. A number of ILDs have been described including LIP & GLILD.