Respiratory 3

oelomar's version from 2016-04-19 21:11


Question Answer
What is tuberculosis?An infectious disease generally affecting the lungs (and other parts of the body) caused by four main mycobacterial species collectively termed Mycobacterium tuberculosis complex, the most common being Mycobacterium tuberculosis.
What is the link between HIV/AIDS and tuberculosis?Active infection of TB occurs more often in people with HIV/AIDS. TB is the cause of death in most HIV patients.
What is “primary tuberculosis”?Primary tuberculosis describes the first infection with Mycobacterium tuberculosis (MTb). Once inhaled into the lung, alveolar macrophages ingest the bacteria; the bacilli then proliferate inside the macrophages and cause the release of neutrophil chemoattractants and cytokines, resulting in inflammatory cell infiltrate reaching the lung.
What is meant by “caseation” which is seen in tuberculosis, and what causes it?This is a condition characteristic of TB in which diseased tissue forms a firm, dry mass like cheese. Following an intradermal injection, a skin reaction will occur, in which there are granulomatous lesions consisting of a central area of necrotic material – the caseation. This occurs because the macrophages (which have the bacilli proliferating within them) present the antigen to the T lymphocytes with the development of a cellular immune response. A delayed hypersensitivity reaction occurs, resulting in tissue necrosis and formation of a granuloma.
What is “latent tuberculosis”?In the majority of people who are infected by Mycobacterium tuberculosis, the immune system contains the infection and the patient develops cell-mediated immune memory to the bacteria. The patient has the TB bacteria in their body, but there are no symptoms. However, there is a risk that the patient will become ill with active TB later on.
What is “reactivation tuberculosis”?The majority of TB cases are due to reactivation of latent infection. The initial contact usually occurred many years or decades earlier.
Name some of the factors implicated in the reactivation of latent tuberculosis.HIV co-infection, immunosuppressant therapy (including corticosteroids), diabetes mellitus, end-stage chronic kidney disease, malnutrition, ageing.


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What are the clinical features of pulmonary tuberculosis?Frequently symptomatic with a productive cough with or without haemoptysis, along with systemic symptoms of weight loss, fevers, and sweats. Where there is laryngeal involvement, hoarse voice and severe cough are found. If disease involves the pleura, then pleuritic pain is a frequent presenting complaint. Chest x-ray demonstrates several findings including consolidation, with or without cavitation, and pleural effusion.
What is miliary tuberculosis?A type of tuberculosis characterised by a wide distribution into the human body and by the tiny size of the lesions. It is a form of TB that is the result of Mycobacterium tuberculosis travelling to extrapulmonary organs such as the liver, spleen, and kidneys.
What does a chest x-ray show in miliary tuberculosis?Multiple nodules which appear like millet seeds, hence the term “miliary”.
What is Pott’s disease?A form of tuberculosis that occurs outside the lungs whereby disease is seen in the vertebrae.
What is tuberculin?An extract of Mycobacterium tuberculosis that is used in skin testing for TB. The most important type of tuberculin is purified protein derivative (PPD).
What is the Mantoux test?A screening tool for tuberculosis in which tuberculin is injected intradermally, and then read 48-72 hours later. A person who has been exposed to the bacteria is expected to mount an immune response in the skin containing the bacterial proteins. The reaction is read by measuring the diameter of induration (palpable raised, hardened area) across the forearm (perpendicular to the long axis) in millimetres. Note that this test is for latent, not active, TB.
How can sputum be used to diagnose tuberculosis?Morning sputum on 3 consecutive days for acid fast bacilli (AFB) culture is collected.


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How is tuberculosis treated? Name any possible adverse effects of the drugs used.The duration of treatment depends on the site of disease, e.g. pulmonary and miliary TB’s duration of therapy is 6 months; CNS TB is 12 months; latent TB is 3 months or 6 months. Patients are given “RIPE” – Rifampicin, Isoniazid (could cause isoniazid-induced neuropathy), Pyrazinamide (may cause hepatotoxicity and precipitate hyperuricaemic gout), Ethambutol (can cause optic neuropathy, red-green colour blindness).
Isoniazid can cause peripheral nerve damage. What can be taken to help minimise this risk?Pyridoxine.
What is the link between rifampicin and the contraceptive pill?Rifampicin inhibits the contraceptive pill.
In whom does drug resistance to TB occur?The development of resistance after initial drug sensitivity (secondary drug resistance) occurs in patients who do not comply with the treatment regimens.
What is multi-drug resistant tuberculosis?A form of TB that is resistant to two or more of the primary drugs (isoniazid, rifampicin) used for the treatment of TB.
What is extensive-drug resistant tuberculosis?A rare type of multi-drug resistant TB that is resistant to isoniazid, rifampicin, quinolone, and at least one of the following second-line drugs: kanamycin, capteomycin, amikacin.
Which nerve can be adversely affected by streptomycin?Vestibular nerve, thereby causing tinnitus, vertigo, and ataxia.
When is streptomycin used to treat tuberculosis patients?This drug is used only if patients are very ill, have multidrug-resistant TB or are not responding adequately to therapy.
Sometimes, patients receive chemoprophylaxis with isoniazid for tuberculosis. Why/when would this happen?When patients have any chest x-ray changes compatible with previous TB, and are about to undergo long term treatment that has an immunosuppressive effect.
What vaccine is given to prevent tuberculosis?BCG vaccine.
What is the link between rifampicin and the colour orange?One of the common side-effects of rifampicin is that it can cause saliva, tears, sweat, urine, and faeces to be orange-red in colour (non-hazardous side-effect).


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What is the normal pulmonary blood pressure, and what is pulmonary hypertension?Normal pulmonary-artery pressure is about 14 mmHg at rest. If the pressure in the pulmonary artery is greater than 25mm Hg at rest and 30 mmHg during exercise, it is abnormally high and is called pulmonary hypertension.
What is the most common cause of pulmonary hypertension?COPD.
What are the clinical features of pulmonary hypertension?Dyspnoea on exertion, fatigue, lethargy, chest pain, oedema, abdominal distention, syncope with exertion. Presents with a loud, palpable S2 (often split), systolic ejection murmur, S4, or parasternal heave.
How is pulmonary hypertension diagnosed?Cardiac catheterisation can directly measure the pulmonary artery pressures. CT pulmonary angiogram is diagnostic of primary pulmonary hypertension. Chest x-ray shows enlargement of central pulmonary arteries. ECG shows right ventricular hypertrophy.
What is venous insufficiency?A medical condition in which the flow of blood through the veins is inadequate, causing blood to pool in the legs.
What are the clinical features of venous insufficiency?Characterised by chronic pitting oedema, often associated with brown haemosiderin skin deposits on the lower legs. The skin changes can progress to dermatitis and ulceration, which usually occur over the medial malleoli. Other signs and symptoms include varicose veins.
What is an easy way for one to differentiate between venous insufficiency and lymphoedema?There is pitting oedema in venous insufficiency, but this is not present in lymphoedema.


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What are the most common sites for venous thrombosis?Thrombosis can occur in any vein, but the veins of the leg and the pelvis are the most common sites.
What is the difference between superficial veins and deep veins?There are two sets of veins in the legs. The important veins located within the leg muscles called deep veins carry nearly all the venous return to the heart. In contrast, the second set of veins are called superficial veins, so named because they are closer to the skin in the subcutaneous tissue. Because of their superficial location outside of the musculature, there is minimal assistance from muscle contraction in moving blood upwards against gravity. Rather, the superficial veins rely mainly on their one-way valves to return the blood.
What is superficial thrombophlebitis?Also known as superficial vein thrombosis, this is thrombosis and inflammation of superficial veins, commonly the saphenous veins, which presents are painful induration with erythema.
Does embolism occur from superficial vein thrombosis?No.
Superficial vein thrombosis can predispose to poor wound healing and varicose ulcers. True or false?True.
What is deep vein thrombosis, and which area of the body is most commonly affected?Formation of a thrombus within a deep vein, predominantly in the legs, but particularly in veins of the calf.
What are the clinical features of deep vein thrombosis?Pain in the calf, often with swelling, redness and engorged superficial veins. The affected calf is often warmer and there may be ankle oedema. Homan’s sign is often present.


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What is Homan’s sign?Pain in the calf upon dorsiflexion of the foot with the leg extended.
In a DVT, a pulmonary embolism is more likely to occur if the thrombosis is confined to the veins below the knees as opposed to an iliofemoral thrombosis. True or false?False. Pulmonary embolism can occur with any deep vein thrombosis but is more frequent from an iliofemoral thrombosis, and is rare with thrombosis confined to veins below the knee.
How is deep vein thrombosis treated?The main aim of therapy is to prevent a pulmonary embolism. Bed rest is advised until the patient is fully anticoagulated. The patient should then be mobilised, with elastic stocking giving graduated pressure over the leg. DVTs are treated with LMWH. Warfarin is started immediately and the heparin is stopped when the INR is in the target range – usually after 5 days. Recurrent DVTs need permanent anticoagulants.
What is the difference in the duration of anticoagulation therapy in provoked and unprovoked DVTs?In a provoked DVT, the anticoagulation therapy is for 3 months. In an unprovoked DVT, therapy is for 6 months.
What is the target INR for patients with DVT (i.e. patients on warfarin)?2.5 (range 2.0-3.0).
The Wells score is a clinical prediction rule for DVT. What are the highest and lowest scores?The highest is 9, and the lowest is -2.
How is the Wells score for DVT interpreted?2 points or more = DVT is likely; perform a proximal leg vein ultrasound scan within 4 hours and if negative perform d-dimer. 1 point or less = DVT is unlikely; perform d-dimer to rule out DVT.


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What is a pulmonary embolism?Blockage of an artery in the lungs by a substance that has travelled from elsewhere in the body through the bloodstream. Severe cases can lead to sudden death.
What intervention can be undertaken in people who have recurrent PE’s in order to help prevent them from reoccurring?An inferior vena cava filter.
Where do most pulmonary emboli come from?From the popliteal, femoral, or iliac veins.
What are the clinical features of a pulmonary embolism?Sudden onset of unexplained dyspnoea is the most common, and often the only symptom of pulmonary embolism. Pleuritic chest pain and haemoptysis are present only when infarction has occurred.
If plasma d-dimer is undetectable, then a pulmonary embolism is likely. True or false?False. If plasma d-dimer is undetectable, is excludes a diagnosis of PE.
What is the first line investigation for diagnosing a pulmonary embolism?CT pulmonary angiogram.
How is a pulmonary embolism treated?All patients should receive high-flow oxygen (60-100%) unless they have significant chronic lung disease. Patients should be anticoagulated initially with subcutaneous LMWH or fondaparinux or IM unfractionated heparin followed by warfarin therapy.


Question Answer
What are the effects of heparin toxicity?Bleeding, thrombocytopenia, osteoporosis, drug-drug interactions.
How does one counter heparin toxicity?Protamine sulfate.
What are the effects of warfarin toxicity?Bleeding, teratogenic, skin/tissue necrosis, drug-drug interactions.
How does one counter warfarin toxicity?Vitamin K and fresh frozen plasma.
How is heparin taken?Parenterally (IV/subcutaneously).
How is warfarin taken?Orally.
Heparin and warfarin can both cross the placenta. True or false?False, only warfarin can (hence why it is teratogenic).
The Wells score is a clinical predication rule for pulmonary embolism. How is it interpreted?A score of >4 = PE likely – consider diagnostic imaging. A score of 4 or less = PE unlikely – consider d-dimer to rule out PE.

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