An 8-year-old girl is brought to the emergency department due to worsening shortness of breath and chest tightness for the past 2 hours.  On physical examination, the patient speaks in short sentences.  Lung auscultation reveals diffuse wheezing.  During the evaluation, the patient is instructed to take a deep breath and blow as hard as possible into the mouthpiece of a hand-held device.  The measured airflow rate is significantly lower than expected.  Treatment with an inhaled medication is begun.  A repeat evaluation several minutes later shows an increase in the airflow rate.  The administered medication most likely affected which of the following to produce the observed finding in this patient?

A 45-year-old previously healthy man is brought to the emergency department after being hit by a car while cycling.  The patient is hypotensive and tachycardic on arrival and has comminuted fractures of the pelvis and lower extremities.  Volume resuscitation is performed with intravenous fluids and multiple units of packed red blood cells and plasma.  Several hours later, the patient develops worsening dyspnea and hypoxia.  Chest imaging reveals new bilateral infiltrates.  Endotracheal intubation is performed for respiratory support.  Despite aggressive resuscitation, the patient dies 24 hours later.  Autopsy examination of the lungs shows protein-rich fluid within the alveolar airspaces.  Breakdown of the barrier formed by which of the following cells most likely contributed to this patient’s pulmonary pathology?

A 12-year-old boy is brought to the clinic for a follow-up examination.  The patient was admitted to the hospital 3 months ago after a nonfatal drowning event that resulted in severe acute respiratory distress syndrome.  He was intubated and mechanically ventilated for 1 week and then discharged 2 weeks later.  The patient currently feels well and reports mild dyspnea with exertion.  Which of the following parameters is most likely increased in this patient compared to a child with normal cardiopulmonary function?

A 30-year-old previously healthy man experiences worsening dyspnea and hypoxia.  During evaluation, he undergoes direct pulmonary angiography.  Intravenous contrast dye is injected into one of his segmental pulmonary arteries under fluoroscopy, with the results shown below:

Which of the following is the most likely cause of this patient’s hypoxia?

A 28-year-old previously healthy man comes to the urgent care clinic due to shortness of breath.  The patient is on a ski vacation in Breckenridge, Colorado, which is situated at an altitude of 2926 m (9600 ft).  On arrival 4 days ago, he experienced mild headache and nausea that resolved spontaneously, but since yesterday, he has had worsening dyspnea and cough.  The patient now feels short of breath even with minimal exertion.  Temperature is 37.3 C (99.1) F, blood pressure is 134/82 mm Hg, pulse is 98/min, and respirations are 22/min.  Oxygen saturation is 86% on ambient air, which rapidly improves to 95% with supplemental oxygen.  Physical examination shows pink mucous membranes, flat neck veins, bilateral inspiratory crackles, and no heart murmurs or pedal edema.  Chest x-ray reveals patchy alveolar infiltrates.  Which of the following is the most likely cause of this patient’s current condition?

A 64-year-old man comes to the office due to a lump in his neck.  He has a long history of using chewing tobacco.  On examination, there is an ulcerative lesion in the left floor of mouth.  There is also a firm, palpable, nontender left submandibular mass.  Biopsy of the submandibular mass is shown in the exhibit.  Which of the following is the most likely route of spread from the floor of mouth to the submandibular mass?

A 53-year-old woman is admitted to the hospital due to a 3-day history of worsening dyspnea.  On examination, the patient is tachypneic; diffuse, wet, inspiratory crackles are present on pulmonary auscultation.  Chest x-ray reveals bilateral patchy opacities.  Arterial blood gas analysis shows that the patient’s alveolar-arterial gradient (P_AO₂ − P_aO₂) is markedly increased.  Although the patient receives 100% oxygen via a face mask, she has persistent hypoxemia and respiratory distress.  Consequently, she is intubated and placed on mechanical ventilation with 100% oxygen and positive end-expiratory pressure (PEEP).  Results of arterial oxygen measurements are as follows:

The patient’s improved oxygenation following PEEP application is most likely due to a decrease in which of the following?

A 27-year-old man comes to the office due to cough, chest discomfort, and dyspnea on exertion.  Symptoms began approximately a month ago and were initially mild but have gradually worsened.  He has also lost 4.5 kg (10 lb) over the past 2 months.  The patient has no chronic medical conditions.  He smokes a pack of cigarettes a day and drinks an average of 4 beers each weekend.  The patient does not use illegal drugs and has not had multiple sexual partners.  Physical examination is unremarkable.  Chest imaging reveals a large, anterior mediastinal mass.  Subsequent blood work shows elevated levels of β-hCG and alpha fetoprotein.  Which of the following is the most likely diagnosis?

A 9-month-old girl is brought to the emergency department due to fever and cough.  Her symptoms began approximately 2 days ago and have been worsening.  The patient is otherwise healthy except for an episode of acute otitis media 3 weeks ago that resolved following a course of oral amoxicillin.  She lives with her mother, father, and grandmother who have been in good health.  Her mother smokes cigarettes.  Temperature is 38.5 C (101.3 F) and respirations are 34/min.  Pulse oximetry is 95% on room air.  Pulmonary examination reveals mild subcostal retractions and focal crackles in the left lower lobe.  Which of the following underlying factors is most likely contributing to this patient’s current condition?

A 62-year-old man is found dead in his hotel room.  He was traveling for work and had checked into the hotel the night prior.  No other history is available.  Autopsy examination is performed; the lung findings shown below are determined to be the cause of death.

Which of the following is the most likely inciting event that led to this patient’s death?

A 21-year-old man comes to the office due to nasal congestion and rhinorrhea.  It occurs intermittently and is often accompanied by sneezing and itchy, watery eyes.  It began 2 years ago and has worsened in severity.  On examination, the nasal turbinates are edematous with clear rhinorrhea.  There is bilateral conjunctival injection.  Which of the following questions would be most helpful during further workup of this patient’s condition?

A 35-year-old man comes to the clinic for evaluation of exertional dyspnea and dry cough for 8 months.  Oxygen saturation on room air while lying down is 96% and drops to 88% after 6 minutes of walking.  Examination shows fine crackles in both lower lungs.  Chest x-ray reveals reticular densities in both lung fields.  Lung biopsy shows an infiltration of inflammatory cells, predominantly lymphocytes, as well as poorly formed noncaseating granulomas and moderate alveolar septal fibrosis.  Which of the following is the most likely diagnosis?

A 66-year-old man comes to the office due to increasing shortness of breath over the past 3 weeks.  He has had a nonproductive cough for several months, which he attributes to allergies, but also notes a 9-kg (20-lb), unintentional weight loss over this time.  The patient has no prior medical conditions and takes no medications.  He has a 50-pack-year smoking history.  Temperature is 36.7 C (98 F), blood pressure is 120/80 mm Hg, pulse is 72/min, and respirations are 18/min.  Chest x-ray is shown below.

Which of the following would be the expected physical examination finding over the right lower chest?

A 4-year-old boy is brought to the office due to hoarseness.  The parents report that he has had worsening hoarseness for the past year, and his voice now sounds very raspy and rough.  Flexible laryngoscopy is performed and shows bilateral lesions on the true vocal cords.  Removal of these lesions is performed via direct laryngoscopy.  Histopathologic analysis shows a fibrovascular core with benign squamous cells.  The physician explains to the parents that this is likely due to a viral infection acquired through which of the following routes of transmission?

A 65-year-old man comes to the office due to 2 months of fatigue and persistent, nonproductive cough.  He has a history of coronary artery disease and myocardial infarction.  Three years ago, he underwent wide local excision of a melanoma on his posterior neck.  The patient has a 50-pack-year smoking history.  Vital signs are within normal limits.  Chest radiograph reveals multiple lung lesions and hilar lymphadenopathy.  Histopathology from one of the biopsied lung lesions is shown below after staining with hematoxylin and eosin.

These histopathologic findings are most consistent with which of the following diagnoses?

A 36-year-old woman comes to the clinic for evaluation of a 4-month history of nonproductive cough and exertional dyspnea.  Her only other medical problem is frequent heartburn, for which she takes over-the-counter antacids.  Temperature is 37.1 C (98.8 F), blood pressure is 126/74 mm Hg, pulse is 88/min, and respirations are 20/min.  Examination shows bilateral crackles and normal heart sounds.  The remainder of the examination is unremarkable.  Chest imaging shows bilateral interstitial opacities.  Bronchioalveolar lavage reveals >50% of cells being lymphocytes.  Which of the following is the most likely diagnosis?

A 65-year-old man is evaluated for hypotension and increasing shortness of breath shortly after placement of a right-sided subclavian central venous catheter.  The patient was recently diagnosed with colon cancer without metastasis and is scheduled for surgical resection.  Blood pressure is 80/50 mm Hg, pulse is 110/min, and respirations are 24/min.  Examination shows jugular venous distension.  Breath sounds are decreased on the right and the trachea is deviated to the left.  Which of the following is the most likely cause of this patient’s hypotension?

A 52-year-old woman with a history of cirrhosis due to chronic hepatitis C experiences worsening dyspnea.  She has no other medical conditions.  Vital signs are within normal limits.  Physical examination shows normal jugular venous pressure, right-sided dullness to percussion and decreased breath sounds, normal heart sounds, and moderate-sized ascites.  Chest x-ray reveals a large right-sided pleural effusion with no parenchymal lesions.  Thoracentesis yields transudative fluid with normal cell counts.  Which of the following is the most likely underlying mechanism of this patient’s pulmonary findings?

A 72-year-old woman is brought to the emergency department due to exertional chest pain.  The patient is on vacation with her family and her symptoms began after arriving in the Colorado mountains.  She has a history of coronary artery disease but has had no ischemic symptoms over the past several years.  The patient is a lifetime nonsmoker and has no history of lung disease.  Physical examination shows mild hypoxemia, clear lungs, an S4, and no extremity edema.  ECG shows T-wave inversion in the lateral leads.  Serum troponin and D-dimer levels are within normal limits.  It is determined that decreased oxygen levels at high altitude in combination with age-related pulmonary changes lead to an exacerbation of this patient’s preexisting heart condition.  Which of the following respiratory changes most likely contributed to this patient’s increased susceptibility?

A 24-year-old man comes to the office due to nonproductive cough, subjective fevers, right-sided pleuritic chest pain, and increasing dyspnea for the past 4 weeks.  He was empirically treated for pneumonia with levofloxacin at an urgent care center 2 weeks ago but has had no improvement.  The patient is an exchange student from the Philippines.  Temperature is 37.3 C (99.1 F), blood pressure is 118/66 mm Hg, pulse is 90/min, and respirations are 20/min.  Physical examination is remarkable for decreased right-sided breath sounds.  Chest x-ray shows a large, right-sided pleural effusion.  Pleural fluid is drained, and a subsequent chest CT scan reveals right upper lobe infiltrate and calcified hilar adenopathy.  This patient’s pleural fluid analysis is most likely to demonstrate which of the following findings?

A 60-year-old woman is brought to the hospital due to progressive shortness of breath and cough for 2 weeks.  The patient was diagnosed with right breast cancer and completed radiation therapy 6 weeks ago.  Temperature is 37.3 C (99.1 F), blood pressure is 110/70 mm Hg, pulse is 90/min, and respirations are 22/min.  Oxygen saturation is 93% on room air.  Examination reveals inspiratory crackles over the right lung anteriorly; the lungs are otherwise clear to auscultation.  Chest radiograph shows ground-glass opacities in the right lung where radiation was delivered.  Laboratory studies reveal no significant changes.  Acute radiation-induced lung injury is suspected.  Histopathologic examination would most likely reveal formation of which of the following?

A 65-year-old woman with chronic obstructive pulmonary disease comes to the office for a follow-up appointment.  The patient reports increasing shortness of breath that is not relieved by her inhalers.  Her other medical conditions include osteoarthritis.  She is a former smoker with a 45-pack-year history.  Blood pressure is 120/70 mm Hg, pulse is 75/min, and respirations are 22/min.  Oxygen saturation on room air is 91% at rest.  On physical examination, jugular venous pressure is elevated.  There is increased intensity of the pulmonic component of S2.  Breath sounds are decreased bilaterally with scattered wheezes but no crackles.  There is 2+ lower extremity edema.  Which of the following hemodynamic parameters is most likely to be increased in this patient?

A 71-year-old man with a long history of smoking is found to have a new, 4-cm, irregular, spiculated, rounded mass in the right upper lobe.  CT-guided biopsy is performed.  Follow-up chest x-ray after the procedure is shown in the exhibit.  Physical examination of the right lung would most likely show which of the following findings?

A 66-year-old man with poorly controlled type 2 diabetes is admitted to the hospital due to a 2-day history of fever and confusion.  Blood pressure is 110/50 mm Hg.  Pulse oximetry shows an oxygen saturation of 97% on room air.  Examination reveals warm extremities with full peripheral pulses, an infected neuropathic foot ulcer with surrounding cellulitis, and normal lung sounds.  A central venous catheter terminating in the superior vena cava is placed.  Blood aspirated from the catheter appears red.  Blood gas analysis of this venous sample reveals an oxygen saturation of 87% (normal: 65%-70%), and lactate is moderately elevated.  Which of the following is the most likely cause of this patient’s abnormal blood gas findings?

A 45-year-old man comes to the office due to progressive dyspnea on exertion and cough for the past several weeks.  He has had no fever, chills, chest pain, or leg swelling.  The patient is a former smoker with 5-pack-year history.  Temperature is 37.2 C (99 F), blood pressure is 120/70 mm Hg, pulse is 82/min, and respirations are 16/min.  The patient is hypoxemic at rest, with an oxygen saturation of 88% on room air.  Jugular venous pressure is normal.  Lung auscultation shows scattered crackles.  Heart sounds are normal.  Chest x-ray reveals bilateral midalveolar and lower alveolar opacities.  Transbronchial lung biopsy reveals lipoproteinaceous material that is positive on periodic acid–Schiff stain and fills up the terminal bronchioles and alveoli.  Electron microscopy of the substance shows lamellar bodies.  Impaired function of which of the following most likely caused excessive accumulation of the substance in this patient’s alveoli?

A 7-year-old boy is brought to the clinic due to 4 days of worsening left ear pain.  The patient was healthy until last week, when he developed a low-grade fever and congestion, which resolved prior to the sudden development of left ear pain.  Vital signs are normal.  On examination, the patient appears uncomfortable but nontoxic.  The left external ear is nontender with manipulation and has no visible deformities.  Several mobile, 1-cm, anterior cervical lymph nodes are palpated on the left side of the neck.  The left tympanic membrane is erythematous and bulging; there are no visible perforations.  Right ear examination is unremarkable.  Which of the following structures is most likely to become involved with progression of this patient’s infection?

A 70-year-old man comes to the emergency department due to severe right-sided chest pain and shortness of breath after a fall.  While doing yard work, the patient fell off of a ladder, striking his back on several large stones.  Immediately afterward, he felt sharp pain over his posterior chest and had trouble catching his breath.  Blood pressure is 120/80 mm Hg, pulse is 88/min, and respirations are 24/min.  Chest x-ray is shown in the exhibit.  Physical examination of the right side of the chest would most likely reveal which of the following?

A 46-year-old hospitalized man experiences worsening dyspnea and hypoxemia.  The patient was admitted 2 days ago due to alcohol-induced acute pancreatitis.  He has no history of cardiopulmonary disorders.  Chest x-ray reveals new bilateral infiltrates.  His respiratory condition progressively deteriorates and endotracheal intubation is performed.  Mechanical ventilation with a lung-protective strategy is begun and a positive end-expiratory pressure of 10 cm H₂O is applied.  Which of the following is the most likely effect of this latter intervention?

A 62-year-old man is evaluated for shortness of breath.  During pulmonary function testing, the patient performs a forceful and complete exhalation after maximal inhalation.  The results (red curve) are compared to a healthy individual of the same age and sex (black curve), as shown in the image below:

Which of the following is the most likely cause of this patient’s dyspnea?

A 25-year-old man with cystic fibrosis comes to the clinic for a routine follow-up appointment.  The patient has had multiple hospital admissions over the last few years for pulmonary exacerbations.  Pulmonary function testing today will most likely reveal which of the following results?

A 68-year-old man comes to the office for gradually increasing shortness of breath.  He initially experienced symptoms with exertion but now feels short of breath at rest.  The patient has smoked 2 packs of cigarettes per day for 40 years.  Blood pressure is 138/78 mm Hg, pulse is 80/min, and respirations are 22/min.  The chest x-ray is shown in the image below:

Which of the following measures is most likely increased in this patient?

A 32-year-old woman comes to the office for a preemployment examination.  The patient has had mild shortness of breath on exertion over the past year, which she attributes to deconditioning.  Three months ago, an ophthalmologist treated her for anterior uveitis.  The patient has no other medical conditions and takes no medications.  She does not use tobacco, alcohol, or recreational drugs.  Blood pressure is 110/70, pulse is 72/min, and respirations are 14/min.  On physical examination, visual acuity is within normal limits.  There is swelling of the parotid glands and the lungs are clear to auscultation.  Chest x-ray reveals enlarged hilar lymph nodes and nodular pulmonary infiltrates.  Which of the following histopathological findings are most likely to be seen on lymph node biopsy in this patient?

A 48-year-old, previously healthy woman is seen in the clinic for community-onset bacterial pneumonia.  Chest x-ray reveals dense consolidation of the right middle lobe.  Her pulse oximetry is 90% on room air.  The patient is treated with appropriate antibiotics.  Two days later, the patient feels well overall and her pulse oximetry is improved to 98% on room air.  Examination reveals unchanged crackles and egophony from her previous visit.  Which of the following processes best explains this patient’s improved oxygenation?

A 4-hour-old girl is evaluated in the neonatal intensive care unit.  The patient was born at 30 weeks gestation via spontaneous vaginal delivery after 3 hours of labor.  Membranes ruptured at the onset of labor and amniotic fluid appeared clear.  Immediately after birth, the child was placed on continuous positive airway pressure by nasal prongs due to signs of breathing difficulty.  Temperature is 36.7 C (98 F), pulse is 158/min, and respirations are 54/min.  Pulse oximetry is 92% on 60% oxygen.  Examination shows audible grunting and subcostal chest wall retractions.  Cardiac examination shows no murmurs.  A chest x-ray is obtained:

The radiographic findings in this patient most likely represent which of the following?

A 68-year-old man comes to the emergency department due to cough, breathlessness, and chest pain.  The patient has a medical history of hypertension and type 2 diabetes mellitus.  He is a former smoker with a 20-pack-year history.  Temperature is 38 C (100.4 F), blood pressure is 130/80 mm Hg, respirations are 22/min, and oxygen saturation is 95% while breathing ambient air.  The trachea is central in position.  There is dullness to percussion over the lower right lung area compared to the resonancy on the left.  Auscultation of the right lower lobe reveals breath sounds that are loud, hollow, and high-pitched.  When the patient recites the word “ninety-nine” in a normal voice, the sound has higher clarity and intensity over the right base compared to other lung areas.  Which of the following is the most likely cause of these findings?

A 77-year-old man comes to the emergency department due to cough, shortness of breath, sharp chest pains, night sweats, and fatigue for 4 days.  Temperature is 38.3 C (101 F), blood pressure is 110/62 mm Hg, pulse is 106/min, and respirations are 24/min.  The patient appears ill.  Neck veins are nondistended.  There is decreased chest expansion on the right side.  Auscultation reveals decreased breath sounds over the right lung base.  Chest imaging shows a right lower lobe infiltrate and a small, free-flowing pleural effusion on the right side.  Thoracentesis is performed.  Laboratory results are as follows:

Which of the following processes best explains this patient’s pleural fluid findings?

A 62-year-old man comes to the clinic due to a 6-month history of progressive exertional dyspnea.  The patient has an occasional cough but has no palpitations, orthopnea, chest pain, or lower extremity swelling.  Past medical history is insignificant.  He works as an attorney, does not use tobacco, and drinks alcohol only on social occasions.  His symptoms continue to progress, and the patient dies of respiratory failure 3 years after the initial clinic visit.  Autopsy findings include heterogenous lung parenchyma with predominantly subpleural areas of dense collagen deposition, lymphocyte infiltration, and fibroblast proliferation intermixed with areas of normal lung tissue.  Which of the following is the most likely diagnosis?

A 47-year-old man comes to the emergency department due to a 30-minute history of sudden-onset severe chest pain and shortness of breath.  He is on an RV road trip with his family and has had pain in and swelling of the left leg for the past 2 days.  The patient has no significant medical history and takes no medications.  Temperature is 37.2 C (99 F), blood pressure is 90/56 mm Hg, pulse is 124/min, and respirations are 32/min.  Oxygen saturation is 82% on room air.  BMI is 36 kg/m².  ECG shows sinus tachycardia.  Chest x-ray shows no abnormalities.

Item 1 of 2

Which of the following is most likely increased in this patient?

Item 2 of 2

During evaluation, the patient becomes unresponsive and develops cardiac arrest with pulseless electrical activity.  Cardiopulmonary resuscitation and intubation are performed, and the patient is placed on a mechanical ventilator.  Once stabilized, he is admitted to the intensive care unit, and appropriate treatment is administered.  Several days later, a spontaneous-breathing trial is performed to determine readiness to wean off the ventilator.  After the mechanical ventilator settings are adjusted, the following changes are noted as reflected on the graph below.  Dead space ventilation is shaded in black.

Which of the following breathing patterns most likely contributed to this patient’s change from the left bar to the right on the graph above?