A 25-year-old woman with asthma presents to the emergency department in severe cardiovascular distress after taking a theophylline overdose in an attempt to commit suicide. At presentation, she is convulsing, her blood pressure is 80/40 mm Hg, and she has developed a cardiac arrhythmia. Considering the mechanism of action of theophylline, which of the following drugs may be used to counteract its effects?
An overdose of theophylline will cause a decrease in the hydrolysis of cAMP to adenosine monophosphate, resulting in an increasing and potentially toxic level of cAMP. β-Agonists activate adenylate cyclase, which converts ATP to cAMP, so β-blockers may be given to stop this process and reduce cAMP levels.
On a routine check-up, a 65-year-old woman with recently diagnosed adenocarcinoma of the lung is found to have drooping of the right eyelid. Pupillary examination reveals anisocoria with the right pupil smaller than the left. Upon further questioning she reveals that after exerting herself she has to mop the sweat off of her left brow, but does not notice any sweat on her right side. Which of the following is the most likely etiology of the patient’s symptoms?
Apical lung tumor
A tumor at the apex of the lung, or superior sulcus, is known as a Pancoast’s tumor. Due to its location, it can sometimes compress the cervical sympathetic plexus, resulting in Horner’s syndrome (ptosis, miosis, enophthalmos, and anhidrosis), as seen in this patient.
A 50-year-old man is treated for septic shock with multiple antibiotics. Seven days later, the patient is alert and oriented, and his tissue perfusion has returned to normal. However, he describes a terrible feeling that “the world is spinning.” Which of the following therapeutic agents is most likely responsible for this patient’s symptom?
Gentamicin is an aminoglycoside antibiotic used in the treatment of gram-negative rod infections. It is often combined with β-lactam antibiotics because it acts synergistically. Aminoglycosides can cause nephrotoxicity and nonoliguric acute tubular necrosis, or ototoxicity, which can present as either vestibular or cochlear damage. Vestibular toxicity may result in vertigo, nausea, vomiting, or ataxia, whereas cochlear damage causes tinnitus or hearing loss. The patient in this question is experiencing vertigo.
A homeless man who is an alcoholic is brought to the emergency department after being found unconscious by the side of the road. Films taken on arrival show some old trauma to the jaw. X-ray of the chest and CT of the chest reveal a mass lesion in the right lower lobe with spiculation, which appears to extend into the pleural space and involve an adjacent rib. A biopsy specimen of the mass-like lesion is shown in the image. Histologic specimens of bronchial lavage fl uid after biopsy contain numerous hyphae but no malignant cells. What should be included in the treatment regimen for this man’s condition?
This man likely has actinomycosis from infection with Actinomyces israelii, a gram-positive anaerobic bacterium with a branching fi lamentous appearance. The image shows what is known as a “sulfur granule” formed by a colony of Actinomyces fi laments solidifi ed with tissue exudates. The bacteria are generally normal inhabitants of the oral cavity and are found in dental caries. Poor oral hygiene coupled with trauma increases the risk of aspiration of the organism leading to infection. Infections with Actinomyces tend to be chronic and extend through multiple tissue planes. Actinomyces species appear to be susceptible to a wide range of β-lactam agents, which are regarded as agents of fi rst choice in treatment.
A 55-year-old woman with a history of schizophrenia presents to the emergency department with paranoia and active hallucinations. Her agitation is so severe that she has to be restrained for several days. She is started on haloperidol. A few days later she becomes tachycardic and complains of sharp right-sided chest pain. What step should be taken next in the care of this patient?
Start intravenous heparin
Her symptoms of tachycardia and sharp chest pain make it most likely that the patient has developed a pulmonary embolism secondary to being restrained for several days. The best treatment for this would be an anticoagulant. Answer A is incorrect. Ext
A 25-year-old medical student presents with a nonproductive cough, low-grade fever, and malaise of 3 weeks’ duration. He says that a few of the people he studies with have been feeling the same way. Sputum cultures come back negative. The patient denies exposure to farm animals, travel, or HIV. The physician decides to treat for an atypical pneumonia. Which of the following methods could identify the organism responsible for such a pneumonia?
Cold agglutinin testing
Mycoplasma pneumoniae is the most common cause of interstitial (atypical) pneumonia, along with viruses. It cannot be cultured and is diagnosed by the cold agglutinin test, which measures the agglutination of immunoglobulins when they are cooled.
A 50-year-old man complains of shortness of breath on exertion of a few months’ duration. On inspection there is an increased anteroposterior diameter of the chest, pursed lips, and dyspnea with no scleral icterus or jaundice. The patient has a 75-pack-year history of smoking. On physical examination, the patient is tachycardic and has hyperresonant lungs with decreased breath sounds. There is no evidence of hepatomegaly or liver nodules on palpation. Which of the following is the most likely diagnosis?
The patient presents as a classic “pink puffer,” making emphysema the most likely diagnosis. Because smoking is closely linked to centriacinar emphysema, this is the best answer choice. The stem mentions an absence of jaundice and liver problems, making α1-antitrypsin defi ciency, and the associated panacinar emphysema, unlikely.
A 13-year-old white girl with a past medical history of nasal polyps develops severe bronchoconstriction and wheezing after taking a largedose of aspirin, having mistaken it for a cold medication. After presenting to the emergency department, she is found to have a past history of aspirin allergy. Which of the following medications can be used effectively to stop the bronchoconstriction resulting from her aspirin allergy?
Aspirin serves to inhibit the cyclooxygenase enzymes. An allergy to aspirin is thought to result from the diversion of arachidonic acid to the leukotriene pathway when the cyclooxygenase-catalyzed prostaglandin pathway is blocked. The resulting increase in leukotriene synthesis leads to the bronchoconstriction that is typical of an aspirin allergy. Zileuton is an effective inhibitor of the 5-lipoxygenase pathway and thus blocks the conversion of arachidonic acid to leukotrienes. Because of this, zileuton can be used in the treatment of aspirin allergy
A 60-year-old white man presents to his physician with a productive cough of a few months’ duration. The patient reports having three of these episodes over the past 2 years, with each episode lasting 4 months. On physical examination the patient is cyanotic, wheezing, and has crackles in the lungs upon auscultation. Lung biopsy reveals hypertrophy of mucussecreting glands in the bronchioles, with a Reid index >50%. Which of the following is associated with the most likely diagnosis?
Although cigarette smoking is the most common cause of chronic bronchitis, air pollution is also associated with this diagnosis.
During dental procedures, it is possible that small fragments may be aspirated into the trachea and cause aspiration pneumonia. If the patient is sitting upright during the procedure, which of the following is the most common site of aspiration pneumonia?
Right lower lobe
The right main bronchus is more vertical and wider than the left, and aspirated particles are more likely to lodge at the junction of the right inferior and right middle bronchi. Because of this, aspiration pneumonia contracted when an individual is in an upright position is most common in the right lower and middle lobes.
A 57-year-old man with a 40-year history of smoking has chronic obstructive lung disease. He presents to the physician with a blood pressure of 150/95 mm Hg. Which of the following antihypertensive agents is contraindicated in this patient?
Nonselective β-blockers are contraindicated in patients with lung disease because they can cause bronchoconstriction by blocking the β2 receptors responsible for relaxation of bronchial smooth muscle. β2 Agonists are a mainstay of asthma therapy. Acebutolol, atenolol, esmolol, metoprolol, and betaxolol are all cardioselective β1-blockers that could be used in a patient with lung/airway disease. Nadolol is a nonselective βblocker and should not be used in a patient with lung disease. Other nonselective β-blockers include timolol and pindolol.
Gas exchange in the lungs occurs in the alveoli. There are two components to this exchange, diffusion and perfusion. Either of these components can limit the exchange of oxygen from the air into the bloodstream. Which of the following describes perfusionlimited exchange?
Gas equilibrating early along the length of the pulmonary capillary
In perfusion-limited exchange, gas equilibrates early along the length of the pulmonary capillary, so gas exchange can only increase or decrease with increased or decreased blood fl ow, respectively
While examining a patient, the physician notices decreased breath sounds at the right lower lobe, dullness on percussion, and decreased tactile fremitus without tracheal deviation. These fi ndings most likely represent which of the following?
Small to moderate pleural effusions can present without tracheal deviation, decreased breath sounds over the effusion, dullness to percussion, and decreased tactile fremitus
A 65-year-old man with an 80-pack-year history of smoking presents with a cough and increasing dyspnea over the past 6 weeks. A 2-cm diameter mass is seen in the left lower lobe on x-ray of the chest. A sample of nonneoplastic tissue from the lung biopsy is shown in the image. Which of the following types of epithelium not normally present in the lung lines the bronchus shown in this image?
The letter E in the image points to pseudostratified ciliated columnar epithelium, LP refers to the lamina propria, and C refers to hyaline cartilage. In smokers, pseudostratifi ed ciliated columnar epithelium lining the bronchi can undergo metaplasia and transform into stratifi ed squamous epithelium. Stratified squamous epithelium is classifi ed by the flattened shape of the cells in the surface layer. Examples of tissues with stratifi ed squamous epithelium include the skin, mouth, anus, vagina, and esophagus
The oxygen-hemoglobin dissociation curve represents the percent saturation of hemoglobin with oxygen as a function of the partial pressure of oxygen in the blood. This curve is sigmoidal in shape due to the change in affi nity of heme groups for oxygen as each successive oxygen molecule binds. Which of the following in an adult would cause a shift in the curve so that it resembles that of a neonate?
Neonates have high concentrations of fetal hemoglobin in their blood. Fetal hemoglobin has a higher affi nity for oxygen than adult hemoglobin (to allow fetuses to extract oxygen from mother’s blood), therefore fetal oxygen-hemoglobin dissociation curves are left-shifted. Other physiologic conditions that cause left shifts in the curve include increased pH (or reduced H+ concentration), decreased temperature, 2,3-diphosphoglycerate levels, and arterial carbon dioxide pressure.
A 45-year-old African-American woman presents to her physician because of dyspnea and fatigue that has worsened over the past 6 weeks. Over the past week she has noticed the appearance of subcutaneous nodules on her lower extremities. Physical examination reveals dry rales and fl at, elevated lesions on the lower extremities bilaterally. X-ray of the chest shows bilateral hilar lymphadenopathy. Laboratory tests are performed. Which result, although not diagnostic, is most commonly associated with this patient’s condition?
Elevated angiotensin-converting enzyme level
This patient has sarcoidosis involving the lungs and skin. Sarcoidosis is characterized by noncaseating granulomas, and hilar lymphadenopathy is one of the most common fi ndings in this condition. Skin involvement occurs in approximately 25% of patients. Angiotensin-converting enzyme levels are elevated in sarcoidosis due to its overproduction by
A 7-year-old boy is brought to the pediatrician because of a chronic cough, fatty diarrhea, and failure to thrive. Pseudomonas aeruginosa is cultured from his respiratory tract. The physician informs the patient’s parents that their son has a disease that is caused by a mutation in a specifi c ion transporter. This patient has a mutation in the ion transporter of which of the following electrolytes?
Cystic fibrosis (CF) is an autosomal recessive disease that most commonly occurs in the white population. It is usually caused by a mutation in the CF transmembrane conductance regulator (CFTR) protein, a protein that functions as a Cl– channel and is regulated by cAMP. The delta F508 mutation is the most common gene abnormality associated with the disease; it involves the deletion of three base pairs from the gene and the consequent loss of a phenylalanine from the protein. Because three base pairs are deleted, there is no frameshift. Dysfunction of this channel causes abnormal chloride conductance with associated water transport abnormalities, leading to viscous secretions in exocrine glands. Failure to clear secretions in the respiratory tract, pancreas, sweat glands, and other exocrine tissues results in recurrent pneumonias, exocrine pancreatic insufficiency, abnormal sweat gland function, urogenital dysfunction, and, ultimately, failure to thrive
An 18-year-old man comes to the physician complaining of a runny nose, sneezing, and difficulty breathing for the past 2 days. On questioning, the patient says that his younger sister received a baby kitten as a birthday present 2 days ago. The response seen in this patient is mediated by which of the following?
Antigen cross-linking IgE on presensitized mast cells and basophils
This response is an example of a type I hypersensitivity reaction. In these reactions, an allergen cross-links antigenspecifi c IgE on the surface of mast cells and basophils. Subsequently, the mast cells and basophils release vasoactive amines. Since antibodies are preformed in this type of hypersensitivity, the reaction develops quite rapidly.
Inspiration during vigorous exercise involves rapid and deep breathing, which may damage the lungs without mechanisms to prevent overinfl ation of lung tissue. Which of the following is critical to prevent lung damage due to overinfl ation?
Decreased discharge frequency of slowly adapting pulmonary stretch receptors in the lungs during maximal expansion of the parenchyma
The Hering-Breuer refl ex prevents lung tissue damage during active, rapid breathing. The smooth muscle of the tracheobronchial tree contains slowly adapting pulmonary stretch receptors that become active during heavy breathing, but have no effect during rest. The discharge frequency decreases when the lungs have maximally expanded and increases when the lungs are defl ated (when the refl ex is activated).
A 5-year-old girl is brought to the emergency department by her aunt because of a sore throat. The patient is visiting from Nicaragua and has had very few immunizations. Physical examination reveals a grayish-white membrane on the pharynx with marked cervical lymphadenopathy and edema of the throat and neck area. The girl is, however, afebrile. Defi nitive diagnosis is made by gram-positive rods growing on which of the following media?
The disease described in this vignette is diphtheria, which is caused by the gram-positive rod Corynebacterium diphtheriae. Diphtheria classically presents with a grayish-white pseudomembrane on the pharynx or tonsils. Underlying tissue of the throat and neck becomes edematous, and lymphadenopathy develops. Fever is usually mild or absent. It is seen very rarely in vaccinated populations but is endemic to certain parts of the world. Culture of C. diphtheriae requires tellurite to prevent growth of normal upper respiratory tract fl ora.
A 57-year-old man from Colombia presents to the emergency department with fever, night sweats, and a productive cough. A sputum smear shows acid-fast bacilli, and the patient is started on several medications. Three months later, the patient returns to the emergency department with reduced visual acuity and an inability to see the color green. Which of the following is the most likely cause of this patient’s change in visual acuity?
Ethambutol is active only against Mycobacterium tuberculosis, and it is among the fi rst-line agents used to treat tuberculosis (TB) infection (others are isoniazid, rifampin, and pyrazinamide). Ethambutol’s mechanism of action appears to be the inhibition of polymerization of cell wall precursors. Although the drug is generally well tolerated, its most common adverse effects involve ocular toxicity such as the kind described in this question, which usually appears several months after the initiation of treatment. Ethambutol is usually used in an anti-TB regimen with rifampin for patients who either cannot tolerate isoniazid or are infected with isoniazid-resistant M. tuberculosis.
A 12-year-old boy is found unconscious in his bedroom by his parents and is taken to the emergency department. On arrival the patient’s skin is pale and lacks turgor, and there is a sweet scent on his breath. His parents report constant urination and weight loss in the 2 weeks prior to presentation. Laboratory tests show a glucose level of 610 mg/dL, sodium of 130 mEq/L, bicarbonate of 9 mEq/L, and chloride of 95 mEq/L. Which of the following would most likely be associated with this patient’s condition at presentation?
Decreased blood partial pressure of carbon dioxide
This patient most likely has type 1 diabetes mellitus and a resulting ketoacidosis. He has a metabolic acidosis with a large anion gap (>10 mEq) as calculated by the following formula: Anion gap = Na+ – [HCO3 – + Cl–]. This leads to respiratory compensation by deep respiration (Kussmaul’s respiration), resulting in a decrease in blood partial pressure of carbon dioxide. The large anion gap is due to the overproduction of ketones in the absence of insulin production.
Atelectasis (the collapse of alveoli) is a common complication of surgical procedures, especially those requiring general anesthesia, due to impaired surfactant activity and its corresponding effects on alveolar compliance. Which of the following is a characteristic of alveolar compliance?
Increasing the radius of alveoli increases the pressure required to collapse the alveoli
To answer this question, one must remember that the collapsing pressure (the pressure required to keep an alveolus open) is directly related to surface tension and inversely related to the radius of alveoli. This is described by LaPlace’s law, where pressure equals 2 times the surface tension divided by the radius (P = 2T / r). Thus, a larger alveolus will require more pressure to collapse. Surfactant, a substance produced by type II alveolar cells that contains mainly phospholipids and apoproteins, coats alveoli and small airways and serves to reduce surface tension over the air-water interface.
A 7-year-old girl is brought to the pediatrician because of a fever of 39.7º C (103.5º F), trouble swallowing, and drooling. Within a few minutes of arriving at the offi ce, she develops inspiratory stridor and respiratory distress. An x-ray fi lm of her neck is shown in the image. Which of the following is most likely responsible for this patient’s condition?
High fever, dysphagia, drooling, inspiratory stridor, and respiratory distress are all consistent with the diagnosis of epiglottitis. The x-ray fi lm shows thickening of the epiglottic (thumbprint sign) and aryepiglottic folds. The most common etiologic agent associated with epiglottitis is Haemophilus infl uenzae.
An 8-year-old boy comes to the physician with his mother, who wants to discuss respiratory problems that have arisen since an upper respiratory infection 4 months ago. The mother says that the patient has attacks characterized by wheezing and shortness of breath that usually resolve after an hour. On one occasion, an attack required a visit to the emergency department, and the mother remembers the treating physician saying something about an abnormally high level of eosinophils in the patient’s blood. Which cytokine is involved in the pathogenesis of this disease?
This boy suffers from asthma, which is characterized by airway hyperresponsiveness and airfl ow obstruction. This condition can be precipitated by several factors, including allergens, upper respiratory infections, drugs, and stress. Clinically, asthmatics experience episodes of wheezing, coughing, and dyspnea. Sputum samples may demonstrate Curschmann’s spirals and Charcot-Leyden crystals. Blood tests will typically reveal eosinophilia. Other causes of eosinophilia include neoplasms, parasites, collagen vascular diseases, and allergic processes. Asthma is thought to be driven by hyperresponsive T lymphocytes in the lung, producing Th2-type cytokines IL-4, IL-5, and IL-13.
A 46-year-old woman presents to the emergency department with a 4-week history of worsening nausea and lethargy. While she is waiting to see the doctor, the patient experiences a seizure. Her past medical history is signifi cant for hypertension and tuberculosis. Laboratory tests show:
Serum Na+: 125 mEq/L
Serum osmolality: 255 mOsm/kg
Urine osmolality: 1550 mOsm/kg
Which of the following is the most likely diagnosis?
Syndrome of inappropriate ADH secretion
The patient is suffering from the syndrome of inappropriate ADH secretion (SIADH), a condition in which excessive ADH is secreted independent of serum osmolality; this can be seen in pulmonary diseases such as TB. SIADH is caused by central nervous system disturbances, such as strokes; certain drugs, such as cyclophosphamide; and ectopic secretion by certain carcinomas, such as small cell lung carcinoma, as a part of a paraneoplastic syndrome. Excessive ADH secretion can lead to nausea, lethargy, seizures, and even coma. The patient’s laboratory values are typical of someone with SIADH, showing hyponatremia, serum hypo-osmolality, urine hyperosmolarity, and decreased hematocrit secondary to dilution
A 17-year-old girl involved in a car accident presents to the emergency department with penetrating chest trauma to her left side. She is having diffi culty breathing and has an oxygen saturation of 86%. After x-ray of the chest is performed, a chest tube is placed, and her oxygen saturation improves. Which of the following is responsible for her diffi culty breathing upon presentation?
Her intrapleural space is open to the atmosphere
The patient’s penetrating chest wound opened her intrapleural space to the atmosphere. Therefore, as she attempts to inhale, her thoracic cavity expands but air enters through the wound, equalizing the pressure; this prevents the normal expansion of the lungs.
An HIV-positive 24-year-old man from Southern California comes in to his physician’s offi ce with a dry cough, headache, mild wheezing, and slight fever. A complete blood cell count shows elevated eosinophils, and a potassium hydroxide sputum smear is positive for microorganisms. The infectious form of the organism causing the patient’s symptoms possesses which of the following key components?
The description is a typical presentation of coccidioidomycosis, which is endemic to the southwestern United States. This infection causes disseminated disease in immunocompromised patients and forms spherules in tissue. Infection is caused by inhalation of spores of the fungus, Coccidioides immitis. Dipicolinic acid is a key component of fungal spores, which provide the fungus with resistance to dehydration, heat, and chemicals
A 74-year-old patient presents with increased shortness of breath. A sputum sample reveals golden-brown beaded fi bers, which result from iron- and protein-coated fi bers. On CT scan, dense fi brocalcifi c plaques of the parietal pleura are seen. A particular pneumoconiosis is suspected. Which of the following is the likely etiology of the patient’s condition?
Working in a shipyard for 40 years
Working in a shipyard is associated with asbestos exposure. Chronic inhalation of asbestos fi bers can result in asbestosis, which is marked histologically by ferruginous bodies that stain positively with Prussian blue. Asbestosis, unlike most other pneumoconioses, results in marked predisposition to bronchogenic carcinoma and to malignant mesothelioma. Smoking and asbestos exposure together greatly increase one’s risk of developing bronchogenic carcinoma.
A 158.8-kg (350-lb) man with a body mass index of 40 kg/m2 comes to the physician complaining of frequent fatigue, shortness of breath, general sleepiness, and an inability to concentrate. Physical examination shows an extremely obese, tired-looking man with hypertension and an elongated uvula. Which of the following metabolic fi ndings is most likely?
Increased renal HCO3 – reabsorption
This man is likely suffering from obstructive sleep apnea (OSA) secondary to extreme obesity (pickwickian syndrome). During the night he has intermittent cessation of airfl ow at the nose and mouth. During this progressive asphyxia, he has a brief arousal, restores airway patency, and returns to sleep. This patient’s obesity and elongated uvula are very good indicators of OSA, as are his daytime sleepiness, inability to concentrate, and hypertension. Periodic, recurrent asphyxia has the effect of causing a respiratory acidosis that, when present chronically, is compensated for by renal retention of HCO3