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Question 1
Incorrect
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A 6-year-old girl presents very sick with severe acute asthma. She has received one dose of salbutamol through a spacer device, 20 mg of oral prednisolone, and a single dose of nebulized salbutamol and ipratropium bromide combined. She remains sick and has oxygen saturations on air of 90%. Her heart rate is 142 bpm, and her respiratory rate is 40/minute. Examination of her chest reveals widespread wheezing but good air entry.
What is the most appropriate next step in her management?Your Answer: Set up aminophylline infusion
Correct Answer: Further salbutamol nebuliser with 150 mg magnesium sulphate added
Explanation:The BTS guidelines for managing acute asthma in children over the age of 2 recommend the following approaches:
Bronchodilator therapy is the first-line treatment for acute asthma. Inhaled β agonists are preferred, and a pmDI + spacer is the recommended option for children with mild to moderate asthma. It is important to individualize drug dosing based on the severity of the condition and adjust it according to the patient’s response. If initial β agonist treatment does not alleviate symptoms, ipratropium bromide can be added to the nebulized β2 agonist solution. In cases where children with a short duration of acute severe asthma symptoms have an oxygen saturation level below 92%, it is advisable to consider adding 150 mg of magnesium sulfate to each nebulized salbutamol and ipratropium within the first hour.
Long-acting β2 agonists should be discontinued if short-acting β2 agonists are required more frequently than every four hours.
Steroid therapy should be initiated early in the treatment of acute asthma attacks. For children aged 2-5 years, a dose of 20 mg prednisolone is recommended, while children over the age of 5 should receive a dose of 30-40 mg. Children already on maintenance steroid tablets should receive 2 mg/kg prednisolone, up to a maximum dose of 60 mg. If a child vomits after taking the initial dose of prednisolone, the dose should be repeated. In cases where a child is unable to retain orally ingested medication, intravenous steroids should be considered. Typically, treatment with oral steroids for up to three days is sufficient, but the duration of the course should be adjusted based on the time needed for recovery. Tapering is not necessary unless the course of steroids exceeds 14 days.
In cases where initial inhaled therapy does not yield a response in severe asthma attacks, the early addition of a single bolus dose of intravenous salbutamol (15 micrograms/kg over 10 minutes) should be considered. Aminophylline is not recommended for children with mild to moderate acute asthma, but it may be considered for those with severe or life-threatening asthma that is unresponsive to maximum doses of bronchodilators and steroids. The use of IV magnesium sulfate as a treatment for acute asthma in children is considered safe, although its role in management is not yet fully established.
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This question is part of the following fields:
- Respiratory
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Question 2
Incorrect
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A 35-year-old woman presents with difficulty breathing and coughing up blood after a recent trip from Australia. You suspect she may have a pulmonary embolism (PE).
Which of the following statements is true about the two-level PE Wells score?Your Answer: A history of treated cancer 12 months ago scores 1.5 points
Correct Answer: Clinical symptoms and signs of a DVT scores 3 points
Explanation:The two-level PE Wells score has been simplified to determine the likelihood of a pulmonary embolism (PE) into two outcomes: likely or unlikely. A score of over 4 indicates that a PE is likely, while a score of 4 points or less indicates that a PE is unlikely.
The allocation of points is as follows:
– Clinical symptoms and signs of deep vein thrombosis (DVT) = 3 points
– An alternative diagnosis that is less likely than a PE = 3 points
– Heart rate greater than 100 = 1.5 points
– Immobilization for more than 3 days or recent surgery within 4 weeks = 1.5 points
– Previous history of DVT or PE = 1.5 points
– Presence of haemoptysis = 1 point
– Malignancy (currently on treatment, treated in the last 6 months, or palliative care) = 1 point. -
This question is part of the following fields:
- Respiratory
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Question 3
Incorrect
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A 25-year-old woman comes in with a sudden worsening of her asthma symptoms. Her heart rate is 115 bpm, respiratory rate 28/min, and her oxygen levels are at 89% when breathing normally. She is feeling fatigued, and her breathing is weak. When listening to her chest, there are no sounds heard.
Which of the following medication dosages could be given as part of her treatment?Your Answer: Salbutamol 5 mg via air-driven nebuliser
Correct Answer: Aminophylline 5 mg/kg IV loading dose over 20 minutes
Explanation:This patient is displaying symptoms of life-threatening asthma, and the only available option for treatment with the correct dosage is an aminophylline loading dose.
The signs of acute severe asthma in adults include a peak expiratory flow (PEF) of 33-50% of the best or predicted value, a respiratory rate of over 25 breaths per minute, a heart rate of over 110 beats per minute, and an inability to complete sentences in one breath.
On the other hand, life-threatening asthma is characterized by a PEF of less than 33% of the best or predicted value, a blood oxygen saturation level (SpO2) below 92%, a partial pressure of oxygen (PaO2) below 8 kPA, a normal partial pressure of carbon dioxide (PaCO2) within the range of 4.6-6.0 kPa, a silent chest, cyanosis, poor respiratory effort, exhaustion, altered consciousness, and hypotension.
The recommended drug doses for adult acute asthma are as follows: 5 mg of salbutamol delivered through an oxygen-driven nebulizer, 500 mcg of ipratropium bromide via an oxygen-driven nebulizer, 40-50 mg of prednisolone taken orally, 100 mg of hydrocortisone administered intravenously, and 1.2-2 g of magnesium sulfate given intravenously over a period of 20 minutes. Intravenous salbutamol may be considered (250 mcg administered slowly) only when inhaled therapy is not possible, such as in a patient receiving bag-mask ventilation.
According to the current ALS guidelines, IV aminophylline can be considered in cases of severe or life-threatening asthma, following consultation with a senior medical professional. If used, a loading dose of 5 mg/kg should be administered over 20 minutes, followed by a continuous infusion of 500-700 mcg/kg/hour. It is important to maintain serum theophylline levels below 20 mcg/ml to prevent toxicity.
For more information, please refer to the BTS/SIGN Guideline on the Management of Asthma.
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This question is part of the following fields:
- Respiratory
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Question 4
Incorrect
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A 45-year-old man presents with a severe exacerbation of his asthma. You have been asked to administer a loading dose of albuterol. He weighs 70 kg.
What is the appropriate loading dose for him?Your Answer: 125 mg over 1 hour
Correct Answer: 250 mg over 15 minutes
Explanation:The recommended daily oral dose for adults is 900 mg, which should be taken in 2-3 divided doses. For severe asthma or COPD, the initial intravenous dose is 5 mg/kg and should be administered over 10-20 minutes. This can be followed by a continuous infusion of 0.5 mg/kg/hour. In the case of a patient weighing 50 kg, the appropriate loading dose would be 250 mg. It is important to note that the therapeutic range for aminophylline is narrow, ranging from 10-20 microgram/ml. Therefore, it is beneficial to estimate the plasma concentration of aminophylline during long-term treatment.
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This question is part of the following fields:
- Respiratory
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Question 5
Incorrect
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You assess a 65-year-old woman with a history of progressively increasing shortness of breath. As part of the patient's treatment plan, your supervisor requests that you carry out a pleural aspiration.
Based on the BTS guidelines, what is one of the indications for performing a pleural aspiration?Your Answer: Bilateral transudative pleural effusions
Correct Answer: Unilateral exudative pleural effusion
Explanation:A pleural effusion refers to an excess accumulation of fluid in the pleural cavity, which is the space between the parietal and visceral pleura. Normally, this cavity contains a small amount of lubricating fluid, around 5-10 ml, that allows the pleurae to slide smoothly over each other. This fluid also creates surface tension, bringing the two membranes together and ensuring that as the thorax expands, the lungs expand and fill with air. However, when there is too much fluid in the pleural cavity, it hinders breathing by limiting lung expansion.
Percutaneous pleural aspiration is commonly performed for two main reasons. Firstly, it is used to investigate pleural effusion, particularly when it is unilateral and exudative in nature. Secondly, it provides symptomatic relief for breathlessness caused by pleural effusion. However, the British Thoracic Society (BTS) guidelines recommend that pleural aspiration should not be carried out if there is suspicion of unilateral or bilateral transudative effusion, unless there are atypical features or failure of response to therapy. In urgent cases where respiratory distress is caused by pleural effusion, pleural aspiration can also be used to quickly decompress the pleural space.
During the procedure, the patient is typically seated upright with a pillow supporting their arms and head. It is important for the patient not to lean too far forward, as this increases the risk of injury to the liver and spleen. The conventional site for aspiration is in the mid-scapular line, about 10 cm lateral to the spine, and one or two spaces below the upper level of the fluid. To avoid damaging the intercostal nerves and vessels that run just below the rib, the needle should be inserted just above the upper border of the chosen rib.
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This question is part of the following fields:
- Respiratory
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Question 6
Incorrect
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You evaluate a 48-year-old teacher with a persistent dry cough that has been ongoing for several months. The patient also reports mild shortness of breath while walking around the school. They used to smoke but quit ten years ago. The patient has a normal body temperature and all other vital signs are within normal limits. During the examination, finger clubbing is noted on their hands. Chest examination reveals bilateral fine inspiratory crackles at the bases of both lungs, but no wheezing is detected. Spirometry results came back normal.
What is the SINGLE most likely diagnosis?Your Answer: COPD
Correct Answer: Idiopathic pulmonary fibrosis
Explanation:Based on the clinical features of this individual, it is highly likely that they have pulmonary fibrosis. The key to determining the correct diagnosis is to differentiate between extrinsic allergic alveolitis (EAA) and idiopathic pulmonary fibrosis (IPF), also known as cryptogenic fibrosing alveolitis (CFA).
In this case, the gentleman does not have any occupational risk factors for EAA and exhibits digital clubbing. While clubbing is not commonly seen in EAA, it is a frequent occurrence in IPF. Therefore, based on these factors, IPF is the more probable diagnosis.
Spirometry results in IPF can either be normal or show a restrictive pattern, whereas an obstructive pattern would be expected in COPD. The history and clinical features presented do not align with the other diagnoses mentioned in this question.
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This question is part of the following fields:
- Respiratory
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Question 7
Incorrect
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A 32-year-old woman comes in with a history of worsening wheezing for the past three days. She has a history of seasonal allergies during the spring months, which have been more severe than usual in recent weeks. Upon listening to her chest, you can hear scattered polyphonic wheezes. Her peak flow at the time of presentation is 280 L/min, and her personal best peak flow is 550 L/min.
What classification would you assign to this asthma exacerbation?Your Answer: Moderate asthma
Correct Answer: Acute severe asthma
Explanation:This man is experiencing an acute episode of asthma. His initial peak flow measurement is 46% of his best, indicating a severe exacerbation. According to the BTS guidelines, acute asthma can be classified as moderate, acute severe, life-threatening, or near-fatal.
Moderate asthma is characterized by increasing symptoms and a peak expiratory flow rate (PEFR) between 50-75% of the individual’s best or predicted value. There are no signs of acute severe asthma in this case.
Acute severe asthma is identified by any one of the following criteria: a PEFR between 33-50% of the best or predicted value, a respiratory rate exceeding 25 breaths per minute, a heart rate over 110 beats per minute, or the inability to complete sentences in one breath.
Life-threatening asthma is indicated by any one of the following: a PEFR below 33% of the best or predicted value, oxygen saturation (SpO2) below 92%, arterial oxygen pressure (PaO2) below 8 kPa, normal arterial carbon dioxide pressure (PaCO2) between 4.6-6.0 kPa, a silent chest, cyanosis, poor respiratory effort, arrhythmia, exhaustion, altered conscious level, or hypotension.
Near-fatal asthma is characterized by elevated PaCO2 levels and/or the need for mechanical ventilation with increased inflation pressures.
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This question is part of the following fields:
- Respiratory
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Question 8
Incorrect
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A 12-year-old girl from an Irish Traveller community presents with a history of a persistent cough that has been present for the past two weeks. The cough occurs in short bursts with an inhalation followed by a series of hacking coughs. She has never received any immunizations.
What is the MOST suitable test to perform?Your Answer: Oral fluid testing for anti-pertussis toxin IgG antibody levels
Correct Answer: Culture of nasopharyngeal aspirate
Explanation:This presentation strongly suggests a diagnosis of whooping cough, which is an infection of the upper respiratory tract caused by the bacteria Bordetella pertussis. The disease is highly contagious and is transmitted through respiratory droplets. The incubation period is typically 7-21 days, and it is estimated that about 90% of close household contacts will become infected.
The clinical course of whooping cough can be divided into two stages. The first stage, known as the catarrhal stage, is similar to a mild respiratory infection with symptoms such as low-grade fever and a runny nose. A cough may be present, but it is usually mild compared to the second stage. This phase typically lasts about a week.
The second stage, called the paroxysmal stage, is characterized by the development of a distinctive cough. The coughing occurs in spasms, often preceded by an inspiratory whoop sound. These spasms are followed by a series of rapid, hacking coughs. Patients may experience vomiting and may develop subconjunctival hemorrhages and petechiae. Between spasms, patients generally feel well and there are usually no abnormal chest findings. This stage can last up to 3 months, with a gradual recovery over this period. The later stages of this phase are sometimes referred to as the convalescent stage.
Complications of whooping cough can include secondary pneumonia, rib fractures, pneumothorax, hernias, syncopal episodes, encephalopathy, and seizures.
Public Health England (PHE) provides recommendations for testing for whooping cough based on the age of the patient, time since onset of illness, and severity of presentation. For infants under 12 months of age, hospitalised patients should undergo PCR testing, while non-hospitalised patients within two weeks of onset should be tested using culture of a nasopharyngeal swab or aspirate. Non-hospitalised patients presenting over two weeks after onset should be investigated with serology for anti-pertussis toxin IgG antibody levels.
For children over 12 months of age and adults, patients within two weeks of onset should be tested using culture of a nasopharyngeal swab or aspirate. Patients aged 5 to 16 who have not received the vaccine within the last year and present over two weeks after onset should have oral fluid testing for anti-pertussis toxin IgG antibody levels.
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This question is part of the following fields:
- Respiratory
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Question 9
Correct
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A 45-year-old man presents with acute severe asthma. You initiate management for the patient, guided by the most recent BTS guidelines.
According to the BTS guidelines, which of the following is NOT a suitable treatment?Your Answer: 1 hourly ipratropium bromide nebulisers
Explanation:The BTS guidelines for managing acute asthma in adults provide the following recommendations:
Oxygen:
– It is important to give supplementary oxygen to all patients with acute severe asthma who have low levels of oxygen in their blood (hypoxemia). The goal is to maintain a blood oxygen saturation level (SpO2) between 94-98%. Even if pulse oximetry is not available, oxygen should still be administered.β2 agonists therapy:
– High-dose inhaled β2 agonists should be used as the first-line treatment for patients with acute asthma. It is important to administer these medications as early as possible.
– Intravenous β2 agonists should be reserved for patients who cannot reliably use inhaled therapy.
– For patients with life-threatening asthma symptoms, nebulized β2 agonists driven by oxygen are recommended.
– In cases of severe asthma that does not respond well to an initial dose of β2 agonist, continuous nebulization with an appropriate nebulizer may be considered.Ipratropium bromide:
– Nebulized ipratropium bromide (0.5 mg every 4-6 hours) should be added to β2 agonist treatment for patients with acute severe or life-threatening asthma, or those who do not respond well to initial β2 agonist therapy.Steroid therapy:
– Steroids should be given in adequate doses for all cases of acute asthma attacks.
– Prednisolone should be continued at a dose of 40-50 mg daily for at least five days or until the patient recovers.Other therapies:
– Nebulized magnesium is not recommended for the treatment of acute asthma in adults.
– A single dose of intravenous magnesium sulfate may be considered for patients with acute severe asthma (peak expiratory flow rate <50% of the best or predicted value) who do not respond well to inhaled bronchodilator therapy. However, this should only be done after consulting with senior medical staff.
– Routine prescription of antibiotics is not necessary for patients with acute asthma.For more information, please refer to the BTS/SIGN Guideline on the Management of Asthma.
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This question is part of the following fields:
- Respiratory
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Question 10
Correct
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A 45 year old with asthma is brought into the ER due to worsening shortness of breath. You collect an arterial blood gas sample for analysis. What is the typical pH range for arterial blood?
Your Answer: 7.35-7.45
Explanation:Arterial blood gases (ABG) are an important diagnostic tool used to assess a patient’s acid-base status and respiratory function. When obtaining an ABG sample, it is crucial to prioritize safety measures to minimize the risk of infection and harm to the patient. This includes performing hand hygiene before and after the procedure, wearing gloves and protective equipment, disinfecting the puncture site with alcohol, using safety needles when available, and properly disposing of equipment in sharps bins and contaminated waste bins.
To reduce the risk of harm to the patient, it is important to test for collateral circulation using the modified Allen test for radial artery puncture. Additionally, it is essential to inquire about any occlusive vascular conditions or anticoagulation therapy that may affect the procedure. The puncture site should be checked for signs of infection, injury, or previous surgery. After the test, pressure should be applied to the puncture site or the patient should be advised to apply pressure for at least 5 minutes to prevent bleeding.
Interpreting ABG results requires a systematic approach. The core set of results obtained from a blood gas analyser includes the partial pressures of oxygen and carbon dioxide, pH, bicarbonate concentration, and base excess. These values are used to assess the patient’s acid-base status.
The pH value indicates whether the patient is in acidosis, alkalosis, or within the normal range. A pH less than 7.35 indicates acidosis, while a pH greater than 7.45 indicates alkalosis.
The respiratory system is assessed by looking at the partial pressure of carbon dioxide (pCO2). An elevated pCO2 contributes to acidosis, while a low pCO2 contributes to alkalosis.
The metabolic aspect is assessed by looking at the bicarbonate (HCO3-) level and the base excess. A high bicarbonate concentration and base excess indicate alkalosis, while a low bicarbonate concentration and base excess indicate acidosis.
Analyzing the pCO2 and base excess values can help determine the primary disturbance and whether compensation is occurring. For example, a respiratory acidosis (elevated pCO2) may be accompanied by metabolic alkalosis (elevated base excess) as a compensatory response.
The anion gap is another important parameter that can help determine the cause of acidosis. It is calculated by subtracting the sum of chloride and bicarbonate from the sum of sodium and potassium.
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This question is part of the following fields:
- Respiratory
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Question 11
Incorrect
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You are managing a young woman in the Emergency Department who is feeling unwell. She informs you that she has a history of bronchial asthma and has suddenly developed difficulty breathing since this morning. You can hear wheezing when you listen to her chest, and her peripheral oxygen saturation remains low despite receiving nebulized salbutamol. After a few minutes, she starts to become more drowsy. You recently completed your Advanced Life Support (ALS) training and feel confident in managing acutely unwell patients.
What is the most appropriate initial step to take in this situation?Your Answer: Continue to manage the patient regardless of their clinical condition
Correct Answer: Summon the resuscitation team
Explanation:This question discusses the prioritization of patient care, specifically focusing on the initial management of acutely unwell patients. The sequence followed in such cases is known as ‘ABCDE’, which stands for airway, breathing, circulation, disability, and exposure. It is crucial to call for help as soon as possible, as the patient’s condition may deteriorate rapidly. If a patient’s consciousness level is dropping, urgent assistance is required, and it is unlikely that you will be able to handle the situation independently.
While waiting for the resuscitation team to arrive, you will be occupied with managing the patient. Therefore, it is not appropriate to make a phone call to the Emergency Department consultant for advice. Although the Emergency Department nurses may be helpful, it is essential to call the resuscitation team first. Continuing to handle the situation alone, regardless of the patient’s clinical condition, indicates a failure to recognize the need for assistance in this scenario.
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This question is part of the following fields:
- Respiratory
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Question 12
Correct
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A 32-year-old individual presents with a sudden worsening of asthma symptoms. You conduct an arterial blood gas test and find that their PaCO2 level is 4.8 kPa.
How would you categorize this asthma exacerbation?Your Answer: Life-threatening asthma
Explanation:The BTS guidelines categorize acute asthma into four classifications: moderate, acute severe, life-threatening, and near-fatal.
Moderate asthma is characterized by increasing symptoms and a peak expiratory flow rate (PEFR) between 50-75% of the best or predicted value. There are no signs of acute severe asthma present in this classification.
Acute severe asthma is identified by any one of the following criteria: a PEFR between 33-50% of the best or predicted value, a respiratory rate exceeding 25 breaths per minute, a heart rate over 110 beats per minute, or the inability to complete sentences in one breath.
Life-threatening asthma is determined by any one of the following indicators: a PEFR below 33% of the best or predicted value, a blood oxygen saturation level (SpO2) below 92%, a partial pressure of oxygen (PaO2) below 8 kilopascals (kPa), a normal partial pressure of carbon dioxide (PaCO2) between 4.6-6.0 kPa, a silent chest, cyanosis, poor respiratory effort, arrhythmia, exhaustion, altered conscious level, or hypotension.
Near-fatal asthma is characterized by elevated PaCO2 levels and/or the need for mechanical ventilation with increased inflation pressures.
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This question is part of the following fields:
- Respiratory
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Question 13
Incorrect
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A 68-year-old male with a history of COPD presents to the emergency department complaining of worsening shortness of breath. The patient's family informs you that during the previous episode, the patient required BiPAP. What is one of the criteria for initiating BiPAP in COPD patients?
Your Answer: pCO2 < 4.0 KPa
Correct Answer: Patient on maximal medical therapy
Explanation:Before starting BiPAP, it is important for patients with COPD to have already started maximum medical therapy. This includes receiving supplemental oxygen, using nebulizers with salbutamol and ipratropium, taking steroids and antibiotics if necessary, and potentially receiving IV bronchodilators. Additionally, patients should meet the blood gas requirements of having a pH level below 7.35 and a pCO2 level above 6 Kpa. Another criteria for initiating NIV is having a respiratory rate higher than 23.
Further Reading:
Mechanical ventilation is the use of artificial means to assist or replace spontaneous breathing. It can be invasive, involving instrumentation inside the trachea, or non-invasive, where there is no instrumentation of the trachea. Non-invasive mechanical ventilation (NIV) in the emergency department typically refers to the use of CPAP or BiPAP.
CPAP, or continuous positive airways pressure, involves delivering air or oxygen through a tight-fitting face mask to maintain a continuous positive pressure throughout the patient’s respiratory cycle. This helps maintain small airway patency, improves oxygenation, decreases airway resistance, and reduces the work of breathing. CPAP is mainly used for acute cardiogenic pulmonary edema.
BiPAP, or biphasic positive airways pressure, also provides positive airway pressure but with variations during the respiratory cycle. The pressure is higher during inspiration than expiration, generating a tidal volume that assists ventilation. BiPAP is mainly indicated for type 2 respiratory failure in patients with COPD who are already on maximal medical therapy.
The pressure settings for CPAP typically start at 5 cmH2O and can be increased to a maximum of 15 cmH2O. For BiPAP, the starting pressure for expiratory pressure (EPAP) or positive end-expiratory pressure (PEEP) is 3-5 cmH2O, while the starting pressure for inspiratory pressure (IPAP) is 10-15 cmH2O. These pressures can be titrated up if there is persisting hypoxia or acidosis.
In terms of lung protective ventilation, low tidal volumes of 5-8 ml/kg are used to prevent atelectasis and reduce the risk of lung injury. Inspiratory pressures (plateau pressure) should be kept below 30 cm of water, and permissible hypercapnia may be allowed. However, there are contraindications to lung protective ventilation, such as unacceptable levels of hypercapnia, acidosis, and hypoxemia.
Overall, mechanical ventilation, whether invasive or non-invasive, is used in various respiratory and non-respiratory conditions to support or replace spontaneous breathing and improve oxygenation and ventilation.
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This question is part of the following fields:
- Respiratory
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Question 14
Incorrect
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A 45-year-old man presents with a severe exacerbation of his COPD. He has been given a loading dose of aminophylline and you now intend to establish a maintenance infusion. He weighs 70 kg.
What is the appropriate maintenance infusion rate for him?Your Answer: 25 mg/hour
Correct Answer: 30 mg/hour
Explanation:The recommended daily oral dose for adults is 900 mg, which should be taken in 2-3 divided doses. For severe asthma or COPD, the initial intravenous dose is 5 mg/kg and should be administered over 10-20 minutes. This can be followed by a continuous infusion of 0.5 mg/kg/hour. In the case of a 60 kg patient, the appropriate infusion rate would be 30 mg/hour. It is important to note that the therapeutic range for aminophylline is narrow, ranging from 10-20 microgram/ml. Therefore, it is beneficial to estimate the plasma concentration of aminophylline during long-term treatment.
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This question is part of the following fields:
- Respiratory
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Question 15
Incorrect
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A 32-year-old patient with asthma is transferred to the resuscitation area of your Emergency Department due to a worsening of their symptoms. Your consultant administers an initial dose of IV aminophylline, and the patient's symptoms start to improve. Your consultant requests that you monitor the patient's theophylline levels after a suitable period of time.
What is the recommended therapeutic range for theophylline in plasma?Your Answer: 5-10 mg/litre
Correct Answer: 10-20 mg/litre
Explanation:In order to achieve satisfactory bronchodilation, most individuals require a plasma theophylline concentration of 10-20 mg/litre (55-110 micromol/litre). However, it is possible for a lower concentration to still be effective. Adverse effects can occur within the range of 10-20 mg/litre, and their frequency and severity increase when concentrations exceed 20 mg/litre.
To measure plasma theophylline concentration, a blood sample should be taken five days after starting oral treatment and at least three days after any dose adjustment. For modified-release preparations, the blood sample should typically be taken 4-6 hours after an oral dose (specific sampling times may vary, so it is advisable to consult local guidelines). If aminophylline is administered intravenously, a blood sample should be taken 4-6 hours after initiating treatment.
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This question is part of the following fields:
- Respiratory
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Question 16
Incorrect
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You are managing a 68-year-old male patient who has been intubated due to the development of acute severe respiratory distress syndrome (ARDS). While adjusting the ventilator settings, your consultant emphasizes the significance of employing lung protective ventilation to prevent ventilator-induced lung injury (VILI). What is a crucial element of lung protective ventilation?
Your Answer: Maintain plateau pressures of 30-50 cm of water
Correct Answer: Use low tidal volumes
Explanation:Lung protective ventilation involves several important elements, with low tidal volumes being a crucial component. Specifically, using tidal volumes of 5-8 ml/kg is recommended to minimize the risk of lung injury. Additionally, it is important to maintain inspiratory pressures, also known as plateau pressure, below 30 cm of water to further protect the lungs. Lastly, permissible hypercapnia, or allowing for higher levels of carbon dioxide in the blood, is another key aspect of lung protective ventilation.
Further Reading:
ARDS is a severe form of lung injury that occurs in patients with a predisposing risk factor. It is characterized by the onset of respiratory symptoms within 7 days of a known clinical insult, bilateral opacities on chest X-ray, and respiratory failure that cannot be fully explained by cardiac failure or fluid overload. Hypoxemia is also present, as indicated by a specific threshold of the PaO2/FiO2 ratio measured with a minimum requirement of positive end-expiratory pressure (PEEP) ≥5 cm H2O. The severity of ARDS is classified based on the PaO2/FiO2 ratio, with mild, moderate, and severe categories.
Lung protective ventilation is a set of measures aimed at reducing lung damage that may occur as a result of mechanical ventilation. Mechanical ventilation can cause lung damage through various mechanisms, including high air pressure exerted on lung tissues (barotrauma), over distending the lung (volutrauma), repeated opening and closing of lung units (atelectrauma), and the release of inflammatory mediators that can induce lung injury (biotrauma). These mechanisms collectively contribute to ventilator-induced lung injury (VILI).
The key components of lung protective ventilation include using low tidal volumes (5-8 ml/kg), maintaining inspiratory pressures (plateau pressure) below 30 cm of water, and allowing for permissible hypercapnia. However, there are some contraindications to lung protective ventilation, such as an unacceptable level of hypercapnia, acidosis, and hypoxemia. These factors need to be carefully considered when implementing lung protective ventilation strategies in patients with ARDS.
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This question is part of the following fields:
- Respiratory
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Question 17
Correct
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A 32-year-old patient with asthma is transferred to the resuscitation area of your Emergency Department due to a worsening of their symptoms. Your consultant administers an initial dose of intravenous aminophylline, and the patient's symptoms start to improve. The consultant requests that you obtain a blood sample to measure the patient's theophylline levels after an appropriate duration of treatment.
How much time should elapse before obtaining the blood sample following the initiation of this treatment?Your Answer: 4-6 hours
Explanation:In order to achieve satisfactory bronchodilation, most individuals require a plasma theophylline concentration of 10-20 mg/litre (55-110 micromol/litre). However, it is possible for a lower concentration to still be effective. Adverse effects can occur within the range of 10-20 mg/litre, and their frequency and severity increase when concentrations exceed 20 mg/litre.
To measure plasma theophylline concentration, a blood sample should be taken five days after starting oral treatment and at least three days after any dose adjustment. For modified-release preparations, the blood sample should typically be taken 4-6 hours after an oral dose (specific sampling times may vary, so it is advisable to consult local guidelines). If aminophylline is administered intravenously, a blood sample should be taken 4-6 hours after initiating treatment.
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This question is part of the following fields:
- Respiratory
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Question 18
Incorrect
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A 32-year-old woman presents with a history of increased cough and wheeze over the past two days. She suffers from seasonal allergies in the spring months, which has been worse than usual over recent weeks. When auscultating her chest, you can hear scattered polyphonic wheezes. Her peak flow at presentation was 275 L/min, and her best ever peak flow is 500 L/min. After a single salbutamol nebuliser, her peak flow improves to 455 L/min, and she feels much better.
What is the SINGLE most appropriate next step in her management?Your Answer: Start a course of oral amoxicillin
Correct Answer: Give oral prednisolone 40 mg
Explanation:This man is experiencing an acute asthma episode. His initial peak flow is 55% of his best, indicating a moderate exacerbation. In such cases, it is recommended to administer steroids, specifically a dose of prednisolone 40-50 mg orally.
Chest X-rays are not routinely performed to investigate acute asthma. However, they should be considered in certain situations, including suspected pneumomediastinum, consolidation, life-threatening asthma, inadequate response to treatment, and the need for ventilation.
Nebulised ipratropium bromide is only added to treatment with nebulised salbutamol in patients with acute severe or life-threatening asthma, or those who do not respond well to salbutamol therapy. Therefore, it is not necessary in this particular case.
While it may be reasonable to prescribe an antihistamine for a patient with a history of worsening hay fever, it should not be prioritized over treatment with steroids.
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This question is part of the following fields:
- Respiratory
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Question 19
Correct
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A 3-month-old boy is brought in by his parents with a history of breathing difficulties, fever, and a cough. He is irritable and having trouble with feeding. On examination, his temperature is 38.6°C, and you hear fine inspiratory crackles across his chest.
What is the SINGLE most likely diagnosis?Your Answer: Bronchiolitis
Explanation:Bronchiolitis is a short-term infection of the lower respiratory tract that primarily affects infants aged 2 to 6 months. It is commonly caused by a viral infection, with respiratory syncytial virus (RSV) being the most prevalent culprit. RSV infections are most prevalent during the winter months, typically occurring between November and March. In the UK, bronchiolitis is the leading cause of hospitalization among infants.
The typical symptoms of bronchiolitis include fever, difficulty breathing, coughing, poor feeding, irritability, apnoeas (more common in very young infants), and wheezing or fine inspiratory crackles. To confirm the diagnosis, a nasopharyngeal aspirate can be taken for RSV rapid testing. This test is useful in preventing unnecessary further testing and facilitating the isolation of the affected infant.
Most infants with acute bronchiolitis experience a mild, self-limiting illness that does not require hospitalization. Treatment primarily focuses on supportive measures, such as ensuring adequate fluid and nutritional intake and controlling the infant’s temperature. The illness typically lasts for 7 to 10 days.
However, hospital referral and admission are recommended in certain cases, including poor feeding (less than 50% of usual intake over the past 24 hours), lethargy, a history of apnoea, a respiratory rate exceeding 70 breaths per minute, nasal flaring or grunting, severe chest wall recession, cyanosis, oxygen saturations below 90% for children aged 6 weeks and over, and oxygen saturations below 92% for babies under 6 weeks or those with underlying health conditions.
If hospitalization is necessary, treatment involves supportive measures, supplemental oxygen, and nasogastric feeding as needed. There is limited or no evidence supporting the use of antibiotics, antivirals, bronchodilators, corticosteroids, hypertonic saline, or adrenaline nebulizers in the management of bronchiolitis.
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This question is part of the following fields:
- Respiratory
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Question 20
Correct
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A 4-year-old girl presents accompanied by her Mom. She suffers from asthma for which she takes a salbutamol inhaler as needed. She has had a runny nose for the past few days and has developed wheezing this evening.
Which ONE characteristic indicates acute severe asthma in this age range?Your Answer: Use of accessory muscles
Explanation:The presence of certain clinical features can indicate the possibility of acute severe asthma in children over the age of 5. These features include oxygen saturations below 92%, peak flow measurements below 50% of what is expected, a heart rate exceeding 120 beats per minute, a respiratory rate exceeding 30 breaths per minute, and the use of accessory muscles.
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This question is part of the following fields:
- Respiratory
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Question 21
Incorrect
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A 45-year-old woman presents with increasing shortness of breath at rest and severe left shoulder pain. The pain travels down the inner side of her left arm and into her ring and little finger. She has a long history of smoking, having smoked 30 packs of cigarettes per year. During the examination, her voice sounds hoarse and there is muscle wasting in her left hand and forearm. Additionally, she has a left-sided ptosis and miosis.
What is the MOST suitable initial test to perform?Your Answer: Nerve conduction studies
Correct Answer: Chest X-ray
Explanation:This individual, who has been smoking for a long time, is likely to have squamous cell carcinoma of the lung located at the right apex. This particular type of cancer is causing Pancoast’s syndrome. Pancoast’s syndrome typically presents with rib erosion, leading to severe shoulder pain, as well as Horner’s syndrome due to the infiltration of the lower part of the brachial plexus. Additionally, there may be hoarseness of the voice and a ‘bovine cough’ due to a concurrent recurrent laryngeal nerve palsy.
The classic description of Horner’s syndrome includes the following clinical features on the same side as the tumor: miosis (constricted pupil), ptosis (drooping eyelid), anhidrosis (lack of sweating), and enophthalmos (sunken appearance of the eye). A chest X-ray would be able to detect the presence of the apical tumor and confirm the diagnosis.
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This question is part of the following fields:
- Respiratory
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Question 22
Correct
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A 42-year-old woman presents with a history of multiple recent episodes of significant haemoptysis. She reports experiencing haemoptysis and has noticed that her urine appears very dark. During examination, bibasal crepitations are detected. A urine dipstick test reveals positive results for blood and protein.
Her current blood test results are as follows:
Hemoglobin (Hb): 7.9 g/dl (normal range: 13-17 g/dl)
Mean Corpuscular Volume (MCV): 68 fl (normal range: 76-96 fl)
White Cell Count (WCC): 19.5 x 109/l (normal range: 4-11 x 109/l)
Neutrophils: 15.2 x 109/l (normal range: 2.5-7.5 x 109/l)
Lymphocytes: 2.1 x 109/l (normal range: 1.3-3.5 x 109/l)
Eosinophils: 0.21 x 109/l (normal range: 0.04-0.44 x 109/l)
Sodium (Na): 134 mmol/l (normal range: 133-147 mmol/l)
Potassium (K): 4.2 mmol/l (normal range: 3.5-5.0 mmol/l)
Creatinine (Creat): 212 micromol/l (normal range: 60-120 micromol/l)
Urea: 11.8 mmol/l (normal range: 2.5-7.5 mmol/l)
Positive AntiGBM antibodies
Positive c-ANCA
What is the MOST LIKELY diagnosis in this case?Your Answer: Goodpasture’s syndrome
Explanation:The most likely diagnosis in this case is Goodpasture’s syndrome, which is a rare autoimmune vasculitic disorder. It is characterized by a triad of symptoms including pulmonary hemorrhage, glomerulonephritis, and the presence of anti-glomerular basement membrane (Anti-GBM) antibodies. Goodpasture’s syndrome is more commonly seen in men, particularly in smokers. There is also an association with certain HLA types, specifically HLA-B7 and HLA-DRw2.
The clinical features of Goodpasture’s syndrome include constitutional symptoms such as fever, fatigue, nausea, and weight loss. Patients may also experience haemoptysis or pulmonary hemorrhage, chest pain, breathlessness, and inspiratory crackles at the lung bases. Anemia due to intrapulmonary bleeding, arthralgia, rapidly progressive glomerulonephritis, haematuria, hypertension, and hepatosplenomegaly (rarely) may also be present.
Blood tests will reveal an iron deficiency anemia, elevated white cell count, and renal impairment. Elisa for Anti-GBM antibodies is highly sensitive and specific, but it is not widely available. Approximately 30% of patients may also have circulating antineutrophilic cytoplasmic antibodies (ANCAs), although these are not specific for Goodpasture’s syndrome and can be found in other conditions such as Wegener’s granulomatosis.
Diagnosis is typically confirmed through renal biopsy, which can detect the presence of anti-GBM antibodies. The management of Goodpasture’s syndrome involves a combination of plasmapheresis to remove circulating antibodies and the use of corticosteroids or cyclophosphamide.
It is important to note that this patient’s history is inconsistent with a diagnosis of pulmonary embolism, as renal impairment, haematuria, and the presence of ANCAs and anti-GBM antibodies would not be expected. While pulmonary hemorrhage and renal impairment can occur in systemic lupus erythematosus, these are uncommon presentations, and the presence of ANCAs and anti-GBM antibodies would also be inconsistent with this diagnosis.
Churg-Strauss syndrome can present with pulmonary hemorrhage, and c-ANCA may be present, but patients typically have a history of asthma, sinusitis, and eosinophilia. Wegener’s granulomatosis can present similarly to Goodpasture’s syndrome,
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This question is part of the following fields:
- Respiratory
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Question 23
Incorrect
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A 32-year-old individual presents with a sudden worsening of asthma symptoms. You conduct an arterial blood gas test, and their PaCO2 level is 6.3 kPa.
How would you categorize this asthma exacerbation?Your Answer: Acute severe asthma
Correct Answer: Near-fatal asthma
Explanation:This individual has presented with an episode of acute asthma. Their PaCO2 levels are elevated at 6.3 kPa, indicating a near-fatal exacerbation. According to the BTS guidelines, acute asthma can be classified as moderate, acute severe, life-threatening, or near-fatal.
Moderate asthma is characterized by increasing symptoms and a PEFR (peak expiratory flow rate) of 50-75% of the best or predicted value. There are no features of acute severe asthma present in this classification.
Acute severe asthma can be identified by any one of the following criteria: a PEFR of 33-50% of the best or predicted value, a respiratory rate exceeding 25 breaths per minute, a heart rate surpassing 110 beats per minute, or the inability to complete sentences in one breath.
Life-threatening asthma is determined by any one of the following indicators: a PEFR below 33% of the best or predicted value, an SpO2 (oxygen saturation) level below 92%, a PaO2 (partial pressure of oxygen) below 8 kPa, normal PaCO2 levels (ranging from 4.6-6.0 kPa), a silent chest, cyanosis, poor respiratory effort, arrhythmia, exhaustion, altered conscious level, or hypotension.
Near-fatal asthma is characterized by a raised PaCO2 level and/or the need for mechanical ventilation with elevated inflation pressures.
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This question is part of the following fields:
- Respiratory
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Question 24
Correct
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A 6-week-old baby girl presents with a low-grade fever, feeding difficulties, and a persistent cough that have been present for the past three days. You suspect bronchiolitis as the diagnosis.
What is the MOST likely causative organism in this case?Your Answer: Respiratory syncytial virus
Explanation:Bronchiolitis is a common respiratory infection that primarily affects infants. It typically occurs between the ages of 3-6 months and is most prevalent during the winter months from November to March. The main culprit behind bronchiolitis is the respiratory syncytial virus, accounting for about 70% of cases. However, other viruses like parainfluenza, influenza, adenovirus, coronavirus, and rhinovirus can also cause this infection.
The clinical presentation of bronchiolitis usually starts with symptoms resembling a common cold, which last for the first 2-3 days. Infants may experience poor feeding, rapid breathing (tachypnoea), nasal flaring, and grunting. Chest wall recessions, bilateral fine crepitations, and wheezing may also be observed. In severe cases, apnoea, a temporary cessation of breathing, can occur.
Bronchiolitis is a self-limiting illness, meaning it resolves on its own over time. Therefore, treatment mainly focuses on supportive care. However, infants with oxygen saturations below 92% may require oxygen administration. If an infant is unable to maintain oral intake or hydration, nasogastric feeding should be considered. Nasal suction is recommended to clear secretions in infants experiencing respiratory distress due to nasal blockage.
It is important to note that there is no evidence supporting the use of antivirals (such as ribavirin), antibiotics, beta 2 agonists, anticholinergics, or corticosteroids in the management of bronchiolitis. These interventions are not recommended for this condition.
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This question is part of the following fields:
- Respiratory
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Question 25
Correct
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A 45-year-old Irish woman comes to you with a complaint of increasing shortness of breath. During the interview, she mentions that she has been experiencing joint pain and painful skin lesions on her shins for the past few months. A chest X-ray is performed and shows bilateral hilar lymphadenopathy.
What is the SINGLE most probable diagnosis?Your Answer: Sarcoidosis
Explanation:The patient presents with a medical history and physical examination findings that are consistent with a diagnosis of Löfgren’s syndrome, which is a specific subtype of sarcoidosis. This syndrome is most commonly observed in women in their 30s and 40s, and it is more prevalent among individuals of Nordic and Irish descent.
Löfgren’s syndrome is typically characterized by a triad of clinical features, including bilateral hilar lymphadenopathy seen on chest X-ray, erythema nodosum, and arthralgia, with a particular emphasis on ankle involvement. Additionally, other symptoms commonly associated with sarcoidosis may also be present, such as a dry cough, breathlessness, fever, night sweats, malaise, weight loss, Achilles tendonitis, and uveitis.
In order to further evaluate this patient’s condition, it is recommended to refer them to a respiratory specialist for additional investigations. These investigations may include measuring the serum calcium level, as it may be elevated, and assessing the serum angiotensin-converting enzyme (ACE) level, which may also be elevated. A high-resolution CT scan can be performed to assess the extent of involvement and identify specific lymph nodes for potential biopsy. If there are any atypical features, a lymph node biopsy may be necessary. Lung function tests can be conducted to evaluate the patient’s vital capacity, and an MRI scan of the ankles may also be considered.
Fortunately, the prognosis for Löfgren’s syndrome is generally very good, and it is considered a self-limiting and benign condition. The patient can expect to recover within a timeframe of six months to two years.
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This question is part of the following fields:
- Respiratory
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Question 26
Correct
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A 32-year-old woman with a documented history of asthma arrives with severe difficulty breathing and wheezing. After initial assessment, it is determined that she is experiencing a life-threatening asthma attack, and she is immediately transferred to the resuscitation area. An arterial blood gas is obtained to aid in her treatment.
What type of acid-base imbalance would you anticipate as a result of this life-threatening asthma episode?Your Answer: Respiratory acidosis
Explanation:The following list provides a summary of common causes for different acid-base disorders.
Respiratory alkalosis can be caused by hyperventilation, such as during periods of anxiety. It can also be a result of conditions like pulmonary embolism, CNS disorders (such as stroke or encephalitis), altitude, pregnancy, or the early stages of aspirin overdose.
Respiratory acidosis is often associated with chronic obstructive pulmonary disease (COPD) or life-threatening asthma. It can also occur due to pulmonary edema, sedative drug overdose (such as opiates or benzodiazepines), neuromuscular disease, obesity, or other respiratory conditions.
Metabolic alkalosis can be caused by vomiting, potassium depletion (often due to diuretic usage), Cushing’s syndrome, or Conn’s syndrome.
Metabolic acidosis with a raised anion gap can occur due to lactic acidosis (such as in cases of hypoxemia, shock, sepsis, or infarction) or ketoacidosis (such as in diabetes, starvation, or alcohol excess). It can also be a result of renal failure or poisoning (such as in late stages of aspirin overdose, methanol or ethylene glycol ingestion).
Metabolic acidosis with a normal anion gap can be caused by conditions like renal tubular acidosis, diarrhea, ammonium chloride ingestion, or adrenal insufficiency.
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This question is part of the following fields:
- Respiratory
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Question 27
Correct
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You assess a patient who came in with chest discomfort and difficulty breathing. They have been diagnosed with a spontaneous pneumothorax and their initial attempt at pleural aspiration was unsuccessful. The pneumothorax is still significant in size, and the patient continues to experience breathlessness. You get ready to insert a Seldinger chest drain into the 'safe triangle'.
What is the lower boundary of the 'safe triangle'?Your Answer: 5th intercostal space
Explanation:The British Thoracic Society (BTS) advises that chest drains should be inserted within the safe triangle to minimize the risk of harm to underlying structures and prevent damage to muscle and breast tissue, which can result in unsightly scarring. The safe triangle is defined by the base of the axilla, the lateral border of the latissimus dorsi, the lateral border of the pectoralis major, and the 5th intercostal space.
There are several potential complications associated with the insertion of small-bore chest drains. These include puncture of the intercostal artery, accidental perforation of organs due to over-introduction of the dilator into the chest cavity, hospital-acquired pleural infection caused by a non-aseptic technique, inadequate stay suture that may lead to the chest tube falling out, and tube blockage, which may occur more frequently compared to larger bore Argyle drains.
For more information on this topic, please refer to the British Thoracic Society pleural disease guidelines.
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This question is part of the following fields:
- Respiratory
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Question 28
Incorrect
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A 6-month-old baby boy is brought to the Emergency Department with a 3-day history of cold symptoms. He is coughing frequently, and his mother has noticed that he is wheezing. He is now having difficulty with feeding and appears fatigued. On examination, his respiratory rate is 60, and you can see flaring of the nostrils and chest wall retractions. Chest examination reveals bilateral fine crackles and high-pitched expiratory wheezing in both lung fields.
What is the SINGLE most likely diagnosis?Your Answer: Croup
Correct Answer: Bronchiolitis
Explanation:Bronchiolitis is a common respiratory infection that primarily affects infants. It typically occurs between the ages of 3-6 months and is most prevalent during the winter months from November to March. The main culprit behind bronchiolitis is the respiratory syncytial virus, accounting for about 70% of cases. However, other viruses like parainfluenza, influenza, adenovirus, coronavirus, and rhinovirus can also cause this infection.
The clinical presentation of bronchiolitis usually starts with symptoms resembling a common cold, which last for the first 2-3 days. Infants may experience poor feeding, rapid breathing (tachypnoea), nasal flaring, and grunting. Chest wall recessions, bilateral fine crepitations, and wheezing may also be observed. In severe cases, apnoea, a temporary cessation of breathing, can occur.
Bronchiolitis is a self-limiting illness, meaning it resolves on its own over time. Therefore, treatment mainly focuses on supportive care. However, infants with oxygen saturations below 92% may require oxygen administration. If an infant is unable to maintain oral intake or hydration, nasogastric feeding should be considered. Nasal suction is recommended to clear secretions in infants experiencing respiratory distress due to nasal blockage.
It is important to note that there is no evidence supporting the use of antivirals (such as ribavirin), antibiotics, beta 2 agonists, anticholinergics, or corticosteroids in the management of bronchiolitis. These interventions are not recommended for this condition.
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This question is part of the following fields:
- Respiratory
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Question 29
Correct
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A 4-year-old girl is diagnosed with whooping cough. There are two individuals in the household who are considered to be in a 'priority group' for post-exposure chemoprophylaxis.
What is the BEST antibiotic to prescribe for this purpose?Your Answer: Erythromycin
Explanation:Whooping cough is a respiratory infection caused by the bacteria Bordetella pertussis. It is highly contagious and can be transmitted to about 90% of close household contacts. The Health Protection Agency has identified two priority groups for public health action in managing whooping cough contacts.
Group 1 consists of individuals who are at a higher risk of severe or complicated infection. This includes infants under one year old who have received less than three doses of the pertussis vaccine.
Group 2 consists of individuals who are at a higher risk of transmitting the infection to those in Group 1. This includes pregnant women who are at or beyond 32 weeks of gestation, healthcare workers who work with infants and pregnant women, individuals who work with infants too young to be vaccinated (under 4 months old), and individuals who share a household with infants too young to be vaccinated.
According to current guidance, antibiotic prophylaxis with a macrolide antibiotic, like erythromycin, should only be offered to close contacts if two criteria are met. First, the index case (the person with whooping cough) must have developed symptoms within the past 21 days. Second, there must be a close contact in one of the two priority groups.
If both criteria are met, all contacts, regardless of their vaccination status and age, should be offered chemoprophylaxis. In this case, the mother is in Group 2, so the current recommendation is that all household contacts, including the mother, father, and brother, should receive chemoprophylaxis.
Additionally, immunization or a booster dose should be considered for those who have been offered chemoprophylaxis, depending on their current vaccination status.
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This question is part of the following fields:
- Respiratory
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Question 30
Incorrect
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A 6 month old girl is brought into the emergency department with a history of being submerged in the pool while swimming with her parents. One of the parents explains that the child was floating on a pool noodle when a wave hit, causing the child to fall off the noodle. The child was not wearing any flotation devices and it took approximately 1 minute to find and rescue her from the water. Your consultant mentions that the child's diving reflex would have been activated. Which of the following statements accurately describes the diving reflex?
Your Answer: Increases cardiac output
Correct Answer: Results in peripheral vasoconstriction
Explanation:The diving reflex occurs when the face comes into contact with cold water, leading to apnoea, bradycardia, and peripheral vasoconstriction. This response helps decrease the workload on the heart, lower oxygen demand in the heart muscle, and ensure adequate blood flow to the brain and vital organs. The trigeminal nerve (CN V) is responsible for transmitting sensory information, while the vagus nerve (CN X) primarily controls the motor response. This reflex is more prominent in young children and is believed to contribute to their improved survival rates in prolonged submersion in cold water.
Further Reading:
Drowning is the process of experiencing respiratory impairment from submersion or immersion in liquid. It can be classified as cold-water or warm-water drowning. Risk factors for drowning include young age and male sex. Drowning impairs lung function and gas exchange, leading to hypoxemia and acidosis. It also causes cardiovascular instability, which contributes to metabolic acidosis and cell death.
When someone is submerged or immersed, they will voluntarily hold their breath to prevent aspiration of water. However, continued breath holding causes progressive hypoxia and hypercapnia, leading to acidosis. Eventually, the respiratory center sends signals to the respiratory muscles, forcing the individual to take an involuntary breath and allowing water to be aspirated into the lungs. Water entering the lungs stimulates a reflex laryngospasm that prevents further penetration of water. Aspirated water can cause significant hypoxia and damage to the alveoli, leading to acute respiratory distress syndrome (ARDS).
Complications of drowning include cardiac ischemia and infarction, infection with waterborne pathogens, hypothermia, neurological damage, rhabdomyolysis, acute tubular necrosis, and disseminated intravascular coagulation (DIC).
In children, the diving reflex helps reduce hypoxic injury during submersion. It causes apnea, bradycardia, and peripheral vasoconstriction, reducing cardiac output and myocardial oxygen demand while maintaining perfusion of the brain and vital organs.
Associated injuries with drowning include head and cervical spine injuries in patients rescued from shallow water. Investigations for drowning include arterial blood gases, chest X-ray, ECG and cardiac monitoring, core temperature measurement, and blood and sputum cultures if secondary infection is suspected.
Management of drowning involves extricating the patient from water in a horizontal position with spinal precautions if possible. Cardiovascular considerations should be taken into account when removing patients from water to prevent hypotension and circulatory collapse. Airway management, supplemental oxygen, and ventilation strategies are important in maintaining oxygenation and preventing further lung injury. Correcting hypotension, electrolyte disturbances, and hypothermia is also necessary. Attempting to drain water from the lungs is ineffective.
Patients without associated physical injury who are asymptomatic and have no evidence of respiratory compromise after six hours can be safely discharged home. Ventilation strategies aim to maintain oxygenation while minimizing ventilator-associated lung injury.
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This question is part of the following fields:
- Respiratory
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