A 7-year-old child is taken to the emergency department because he is feeling short of breath. The episode began about an hour previously while the child was playing sports, when he abruptly developed paroxysms of wheezing and coughing.
When the physician enters the room, he notes that the child is sitting leaning forward and is using his accessory respiratory muscles. Physical examination demonstrates tachypnea and tachycardia. On auscultation, a prolonged expiratory phase with relatively high-pitched wheezes through much of the respiratory cycle are heard. No fine crackles are heard
Q1
Which of the following is the most likely diagnosis?
/ A. Asthma
/ B. Bronchiectasis
/ C. Pneumonia
/ D. Pulmonary edema
/ E. Pulmonary embolus
Q2
If pulmonary studies were performed, which of the following would be most likely to be markedly decreased?
/ A. Forced expiratory volume in the first second
/ B. Functional residual capacity
/ C. Pulmonary blood flow
/ D. Residual volume
/ E. Total lung capacity
Q3
The diagram below shows spirographic tracings of forced expirations from a healthy child (trace X) and from the 7-year-old patient (trace Z).
Which of the following is the FEV1/FVC ratio of the normal child and the patient?
Normal Patient
/ A. 1.0 0.2
/ B. 0.8 0.5
/ C. 0.7 0.3
/ D. 0.5 0.8
/ E. 0.2 1.0
Q4
Which of the following medications will have the fastest onset if the 7-year-old child has an acute attack of his condition?
/ A. Aibuterol inhalation
/ B. Beclomethasone inhalation
/ C. Ephedrine oral
/ D. Salmeterol inhalation
/ E. Theophylline oral tablets
Q5
Approximately an hour after the acute management began, the child began to bring up tenacious, rubbery, white sputum.
The sputum is examined in the laboratory and Charcot-Leyden crystals are found. These are composed of which of the following?
/ A. Bilirubin
/ B. Calcium phosphate
/ C. Cystine
/ D. Protein
/ E. Uric acid
Q6
When the child is discharged, he is placed on both albuterol and flunisolide inhalation preparations. The physician should instruct the child to use flunisolide and albuterol in which of the following ways?
/ A. These agents should not be used together
/ B. Use albuterol several minutes before the flunisolide
/ C. Use albuterol several minutes after the flunisolide
/ D. Use albuterol several hours after the flunisolide
/ E. Wash out his mouth before each use
Q7
Which of the following drugs is a leukotriene modifier indicated for the prophylaxis and treatment of asthma in this child?
/ A. Bitolterol
/ B. Cromolyn sodium
/ C. Ipratropium
/ D. Montelukast
/ E. Theophylline
Q8
Later in life, the patient develops hypertension. Assuming that his respiratory condition is still present, which of the following agents would be the most appropriate pharmacotherapy?
/ A. Atenolol
/ B. Nadolol
/ C. Propranolol
/ D. Sotalol
/ E. Timolol
____________________________________________________________________
Sortness Of Breath Case 2 Answers
A1
The correct answer is A. This patient most likely has asthma based on the initial presentation. Asthma is characterized by reversible airway obstruction, airway inflammation, and bronchospasm of the airways in response to a variety of stimuli. These stimuli may include exposure to known allergens, viral infections, exercise, cold air, crying, screaming, and hard laughing. It is conventional to subdivide asthma into extrinsic (allergy-related) and intrinsic (not related to allergy) subtypes, although this subclassification has been challenged because many patients have overlapping features. The physical features illustrated in this case are typical of a severe asthma attack.
Bronchiectasis (choice B) would not produce episodes of reversible airway obstruction, and would present with fever, cough, and moist crackles.
Pneumonia (choice C) and pulmonary edema (choice D) would develop more slowly, and would be likely to show fine crackles on auscultation.
Pulmonary embolus (choice E) would be very unusual in a young child.
A2
The correct answer is A. The forced expiratory volume in the first second (FEV1) is a commonly used pulmonary function test that evaluates the degree of obstruction present that limits expiration. The degree to which it is reduced is a measure of the severity of the asthmatic attack. In this case, in which the child is in obvious severe respiratory distress, the FEV1 should be markedly decreased.
In many asthmatic patients, functional residual capacity (choice B), residual volume (choice D), and total lung capacity (choice E) are increased.
Pulmonary blood volume (choice C) is not usually measured in asthma, but would be expected to be normal or increased (if PO2 drops).
A3
The correct answer is B. A forced expiration is the simplest test of lung function. The individual breathes in as much air as the lungs can hold and then expels the air as rapidly and as far as possible. The forced vital capacity (FVC) is the vital capacity measured with a forced expiration (FVC = 3 L for patient Z). The forced expiratory volume in one second (FEV1) is the amount of air that can be expelled from the lungs during the first second of a forced expiration (FVC @ 1.5 L for patient Z). FEV1/FVC therefore is a function of airway resistance. Airway resistance is often increased during an asthma attack, which causes FEV1/FVC to decrease. FEV1/FVC is 0.5 in patient Z (1.5/3.0) and 0.8 in the healthy child represented by trace X (4/5).
A4
The correct answer is A. This question is assessing your ability to understand the onset of action for each of the answer choices. We have provided a summary table of the sympathomimetic bronchodilators and selected pharmacokinetic properties.
Based on the chart above you can see that albuterol is indicated for use in the treatment of acute signs and symptoms of asthma since its onset is in less than 5 minutes.
Beclomethasone (choice B) is a glucocorticoid agent, and not a sympathomimetic. It would not have the rapid onset of action required in this case.
Although dosage forms are generally not found on USMLE Step 1, you should immediately recognize that any medication administered orally must be absorbed from the intestinal tract and then reach the site of action. Therefore, you should be able to conclude that oral ephedrine (choice C) and oral theophylline tablets (choice E) will not begin to work for at least 1/2 hour after administration.
Salmeterol inhalation (choice D) has an onset of action of around 20 minutes and has a duration of action of approximately 12 hours. Salmeterol is indicated for the "chronic" treatment/prevention of asthma signs and symptoms.
A5
The correct answer is D. Charcot-Leyden crystals are distinctive hexagonal bipyramidal crystals composed of a protein (thought to function as a lysophospholipase) produced by eosinophils. They can be seen in settings in which tissue eosinophil counts are very high, including allergic conditions, asthma, and parasitic diseases. The sputum in asthma patients also typically shows large number of eosinophils, and may contain Curschmann spirals (mucus casts of smaller airways).
Bilirubin (choice A) can be found in gallstones.
Calcium phosphate (choice B), cystine (choice C), and uric acid (choice E) can be found in urinary tract stones; uric acid can also be found in crystals in tissues in patients with gout.
A6
The correct answer is B. This item deals with the basic science principles underlying a common instruction given by physicians and pharmacists. Albuterol is a sympathomimetic bronchodilator with a rapid onset of action. Therefore, this medication is generally used several minutes before corticosteroids because it dilates the bronchioles and permits the passage of the corticosteroid deep into the lungs (choices A, C, and D are incorrect statements).
Flunisolide is an inhaled corticosteroid indicated for treatment of bronchial asthma when asthma is not controlled with bronchodilators and other non-steroidal medications. Oral fungal infections have occurred with continued use; therefore, patients should rinse out their mouth after each use (choice E is an incorrect statement). These agents are not to be used in treatment of acute asthma as single agents; children may experience HPA axis suppression with prolonged usage. Systemic effects include Cushing's syndrome, hyperglycemia, and glycosuria, and these agents may also cause burning, erythema, and oral dryness.
A7
The correct answer is D. Montelukast is a selective and competitive leukotriene receptor antagonist that inhibits the cysteinyl leukotriene (CYSLT1) receptor. The CYSLT leukotrienes (LTC4, LTD4, and LTE4) are arachidonic acid derivatives that are released from a variety of cells, including mast cells and eosinophils. These leukotrienes bind to the CYSLT receptors in the airways. When these receptors are activated there is a strong correlation with the development of the signs and symptoms of asthma, including airway edema, smooth muscle contraction, and airway inflammation. Blockade of airway CYSLT receptors prevents this. It is indicated for the prophylactic and chronic treatment of asthma in adults and children > 6 years of age.
Bitolterol (choice A) is a beta2 agonist, and is able to relieve reversible bronchospasm by relaxing the smooth muscles of the bronchioles. It is indicated for the treatment for an acute asthma attack.
Cromolyn sodium (choice B) acts as an antiasthmatic and an antiallergic mast cell stabilizer. By inhibiting the degranulation of mast cells, this agent prevents the release of histamine and SRS-A (composed of leukotrienes). Asthma induced by inhalation of antigens can be inhibited by varying degrees with cromolyn pretreatments. This agent has no bronchodilator, antihistaminic, anticholinergic, or anti-inflammatory activity. It is indicated for prophylactic management of severe bronchial asthma, prevention of exercise induced bronchospasm, and prevention of allergic rhinitis.
Ipratropium (choice C) is an antimuscarinic agent that is structurally related to atropine. This agent is a quaternary amine (therefore, positively charged) and there is little systemic absorption. It is indicated for bronchospasm associated with COPD and rhinorrhea.
Theophylline (choice E) is a xanthine derivative medication that relaxes smooth muscle. The mechanism of action may be related to its ability to block adenosine receptors or to inhibit phosphodiesterase. Theophylline is indicated for the symptomatic relief/prevention of bronchial asthma (acute, childhood, nocturnal) as well as reversible bronchospasm associated with chronic bronchitis or emphysema.
A8
The correct answer is A. Patients with disease of the small airways are generally not prescribed beta-receptor blocking agents since these agents can block the bronchodilation produced by endogenous and exogenous catecholamine stimulation of the beta2 receptors. However, relatively low doses of selective beta1 receptor blocking agents, such as atenolol and metoprolol, are relatively well tolerated.
All of the other answer choices are non-selective beta-receptor blocking agents and should not be used in this patient since they are likely to exacerbate the patient's condition.
Posts
No comments:
Post a Comment