Pulmonary

Pulmonary US Medical PG Question 1: A 71-year-old man is admitted to the ICU with a history of severe pancreatitis and new onset difficulty breathing. His vital signs are a blood pressure of 100/60 mm Hg, heart rate of 100/min, respirations of 27/min, temperature of 36.7°C (98.1°F), and oxygen saturation of 85% on room air. Physical examination shows a cachectic male in severe respiratory distress. Rales are heard at the base of each lung. The patient is intubated and a Swan-Ganz catheter is inserted. Pulmonary capillary wedge pressure is 8 mm Hg. An arterial blood gas study reveals a PaO2: FiO2 ratio of 180. The patient is diagnosed with acute respiratory distress syndrome. In which of the following segments of the respiratory tract are the cells responsible for the symptoms observed in this patient found?

• A. Alveolar sacs (Correct Answer)
• B. Terminal bronchioles
• C. Bronchi
• D. Respiratory bronchioles
• E. Bronchioles

Pulmonary Explanation: ***Alveolar sacs*** - **Acute respiratory distress syndrome (ARDS)** is characterized by widespread inflammatory injury to the **alveolar-capillary membrane**, leading to increased permeability and fluid accumulation in the alveolar sacs. - The symptoms, including **severe hypoxemia** (PaO2:FiO2 ratio < 300), **non-cardiogenic pulmonary edema** (PCWP ≤ 18 mmHg), and **bilateral lung infiltrates**, directly result from damage to the **Type I and Type II pneumocytes** and endothelial cells within the alveolar units. *Terminal bronchioles* - These are the last airways that **do not contain alveoli**, primarily involved in air conduction rather than gas exchange. - While inflammation can extend to these structures in severe lung injury, the primary site of impaired gas exchange and fluid accumulation in ARDS occurs distal to them, in the respiratory zone. *Bronchi* - The bronchi are primarily involved in **air conduction** and consist of cartilage, smooth muscle, and ciliated epithelium, but they do not participate in gas exchange. - Injury to the bronchi would manifest as airway obstruction or mucus hypersecretion rather than the diffuse alveolar damage seen in ARDS. *Respiratory bronchioles* - These are the first airways that contain a **small number of alveoli** and participate in gas exchange, but their primary role is still more conductive than the alveolar sacs. - Although they can be affected in ARDS, the most critical damage and symptoms arise from the more extensive gas exchange surface of the alveolar sacs. *Bronchioles* - Bronchioles are small airways lacking cartilage, primarily responsible for **airflow regulation** and conduction. - While they can be affected by inflammation, the extensive impairment of gas exchange and the characteristic pathology of ARDS specifically involves the **alveolar units**, not primarily the bronchioles.

Pulmonary US Medical PG Question 2: A 63-year-old man presents to the emergency department because of progressive difficulty with breathing. He has a history of diabetes, hypertension, and chronic bronchitis. He has been receiving medications to moderate his conditions and reports being compliant with his schedule. He reports a recent difficulty with tackling simple chores in the house. He has not been able to walk for more than 1 block over the past few days. His persistent cough has also been worsening with more formation of sputum. During his diagnosis of bronchitis, about a year ago, he had a 40-pack-year smoking history. The patient is in evident distress and uses his accessory muscles to breathe. The vital signs include: temperature 38.6°C (101.5°F), blood pressure 120/85 mm Hg, pulse 100/min, respiratory rate 26/min, and oxygen (O2) saturation 87%. A decrease in breathing sounds with expiratory wheezes is heard on auscultation of the lungs. The arterial blood gas (ABG) analysis shows: PCO2 60 mm Hg PO2 45 mm Hg pH 7.3 HCO3– 25 mEq/L Which of the following is the most appropriate next step in the treatment?

• A. O2 supplementation (Correct Answer)
• B. Aminophylline
• C. Methylprednisolone
• D. Albuterol
• E. Levofloxacin

Pulmonary Explanation: ***O2 supplementation*** - The patient presents with **severe hypoxemia** (SpO2 87%, PO2 45 mm Hg), which is a life-threatening condition requiring immediate intervention. **Oxygen supplementation** is critical to improve tissue oxygenation and prevent organ damage. - The patient's presentation is consistent with an acute exacerbation of COPD, likely triggered by infection, where *initial management focuses on correcting hypoxemia* and *relieving bronchospasm*. - In COPD patients, **controlled oxygen therapy** is essential (target SpO2 88-92%) to avoid worsening CO2 retention, but with SpO2 of 87% and severe hypoxemia, oxygen remains the immediate priority. *Aminophylline* - Aminophylline is a **methylxanthine** with bronchodilatory effects, but its **narrow therapeutic index** and significant side effect profile (e.g., arrhythmias, seizures) make it a less favored first-line treatment for acute exacerbations of COPD. - While it can be considered in severe cases unresponsive to other therapies, it is not the most appropriate immediate next step given the patient's critical hypoxemia, where oxygen is paramount. *Methylprednisolone* - **Corticosteroids** like methylprednisolone are important in reducing inflammation during COPD exacerbations and improving lung function. - However, their full therapeutic effect takes hours to develop, and they do not immediately address the acute, life-threatening hypoxemia present in this patient. *Albuterol* - Albuterol is a **short-acting beta-agonist (SABA)**, which is crucial for *bronchodilation* in COPD exacerbations. It should be administered promptly to relieve airway obstruction. - While essential in managing the exacerbation, addressing the *severe hypoxemia* with oxygen takes immediate precedence to prevent organ damage, as albuterol will not directly increase oxygen saturation to a safe level alone. *Levofloxacin* - **Antibiotics** like levofloxacin are indicated when there's evidence of a bacterial infection triggering the COPD exacerbation, as suggested by increased sputum purulence and fever. - While important for treating the underlying infection, administering antibiotics does not immediately address the *acute respiratory distress* and *severe hypoxemia*, which are the most urgent concerns.

Pulmonary US Medical PG Question 3: A 67-year-old man is brought to the emergency department because of increasing shortness of breath that began while playing outdoors with his grandson. He has a history of asthma but does not take any medications for it. On arrival, he is alert and oriented. He is out of breath and unable to finish his sentences. His pulse is 130/min, respirations are 23/min and labored, and blood pressure is 110/70 mm Hg. Physical examination shows nasal flaring and sternocleidomastoid muscle use. Pulmonary exam shows poor air movement bilaterally but no wheezing. Cardiac examination shows no abnormalities. Oxygen is administered via non-rebreather mask. He is given three albuterol nebulizer treatments, inhaled ipratropium, and intravenous methylprednisolone. The patient is confused and disoriented. Arterial blood gas analysis shows: pH 7.34 Pco2 44 mm Hg Po2 54 mm Hg O2 saturation 87% Which of the following is the most appropriate next step in management?

• A. Flexible bronchoscopy
• B. Intravenous magnesium sulfate therapy
• C. Endotracheal intubation (Correct Answer)
• D. Continuous albuterol nebulizer therapy
• E. Intravenous theophylline therapy

Pulmonary Explanation: ***Endotracheal intubation*** - The patient's **worsening mental status** (confused and disoriented after initial treatment) and persistent **hypoxemia** (PO2 54 mmHg, O2 sat 87%) despite aggressive therapy indicate impending **respiratory failure** and the need for immediate advanced airway management. - The **normal PCO2** (44 mmHg) in a patient with severe asthma exacerbation is concerning, as it suggests the patient is tiring and unable to maintain adequate ventilation, which can quickly lead to hypercapnia and respiratory arrest. *Flexible bronchoscopy* - This procedure is typically used for **diagnostic purposes** (e.g., investigating foreign body aspiration, airway obstruction, or pneumonia) and is not an immediate life-saving intervention for acute respiratory failure. - It would delay critical airway management and ventilation in a patient with rapidly deteriorating status. *Intravenous magnesium sulfate therapy* - **Magnesium sulfate** is a bronchodilator that can be used as an **adjunctive therapy** in severe asthma exacerbations, particularly in patients not responding to initial bronchodilator treatment. - However, it is not the primary intervention when a patient is showing signs of impending respiratory arrest and requires immediate airway protection and ventilatory support. *Continuous albuterol nebulizer therapy* - The patient has already received three albuterol nebulizer treatments, and while continuous albuterol can be beneficial in severe asthma, the patient's **deteriorating mental status** and **persistent hypoxemia** indicate he needs more aggressive respiratory support than just further bronchodilator therapy. - The immediate priority is to secure the airway and ensure adequate oxygenation and ventilation. *Intravenous theophylline therapy* - **Theophylline** is a bronchodilator with a narrow therapeutic window and significant potential for toxicity, making it a **third-line agent** for severe asthma that is refractory to standard treatments. - Its slow onset of action and potential side effects make it inappropriate as an initial or immediate intervention in a patient with acute respiratory failure.

Pulmonary US Medical PG Question 4: A previously healthy 64-year-old woman comes to the physician because of a dry cough and progressively worsening shortness of breath for the past 2 months. She has not had fever, chills, or night sweats. She has smoked one pack of cigarettes daily for the past 45 years. She appears thin. Examination of the lung shows a prolonged expiratory phase and end-expiratory wheezing. Spirometry shows decreased FEV1:FVC ratio (< 70% predicted), decreased FEV1, and a total lung capacity of 125% of predicted. The diffusion capacity of the lung (DLCO) is decreased. Which of the following is the most likely diagnosis?

• A. Bronchiectasis
• B. Interstitial lung disease
• C. Chronic obstructive pulmonary disease (Correct Answer)
• D. Hypersensitivity pneumonitis
• E. Bronchial asthma

Pulmonary Explanation: ***Chronic obstructive pulmonary disease*** - The patient's long history of **smoking (45 pack-years)**, **prolonged expiratory phase**, and **end-expiratory wheezing** are classic signs of airway obstruction. - Spirometry findings of a **decreased FEV1:FVC ratio** (< 70% predicted), **decreased FEV1**, **increased total lung capacity (TLC)**, and **decreased DLCO** are all highly indicative of **emphysema**, a subtype of COPD. *Bronchiectasis* - While it shares symptoms like cough and SOB, **bronchiectasis** is characterized by permanent **dilatation of bronchi** and profuse, chronic **sputum production**, which is not mentioned here. - Spirometry typically shows **obstructive patterns**, but the marked increase in TLC and decreased DLCO are more specific to emphysema. *Interstitial lung disease* - This condition primarily causes a **restrictive lung pattern**, meaning a decreased TLC and normal or increased FEV1:FVC ratio. - The patient's **increased TLC** and **obstructive spirometry** rule out a purely restrictive process. *Hypersensitivity pneumonitis* - This is an inflammatory response to inhaled antigens, often presenting with **recurrent episodes** of fever, chills, and cough, and can lead to restrictive physiology. - The patient lacks a history of specific **antigen exposure** and presents with an obstructive pattern and increased TLC. *Bronchial asthma* - While asthma shares obstructive features like wheezing and a decreased FEV1:FVC ratio, it is characterized by **reversibility** of airway obstruction and typically does not cause a significantly **elevated TLC** or **decreased DLCO** in uncomplicated cases. - The patient's long smoking history points away from asthma as the primary diagnosis.

Pulmonary US Medical PG Question 5: A 57-year-old man presents to the clinic for a chronic cough over the past 4 months. The patient reports a productive yellow/green cough that is worse at night. He denies any significant precipitating event prior to his symptoms. He denies fever, chest pain, palpitations, weight changes, or abdominal pain, but endorses some difficulty breathing that waxes and wanes. He denies alcohol usage but endorses a 35 pack-year smoking history. A physical examination demonstrates mild wheezes, bibasilar crackles, and mild clubbing of his fingertips. A pulmonary function test is subsequently ordered, and partial results are shown below: Tidal volume: 500 mL Residual volume: 1700 mL Expiratory reserve volume: 1500 mL Inspiratory reserve volume: 3000 mL What is the functional residual capacity of this patient?

• A. 4500 mL
• B. 2000 mL
• C. 2200 mL
• D. 3200 mL (Correct Answer)
• E. 3500 mL

Pulmonary Explanation: ***3200 mL*** - The **functional residual capacity (FRC)** is the volume of air remaining in the lungs after a normal expiration. - It is calculated as the sum of the **expiratory reserve volume (ERV)** and the **residual volume (RV)**. In this case, 1500 mL (ERV) + 1700 mL (RV) = 3200 mL. *4500 mL* - This value represents the sum of the **inspiratory reserve volume (3000 mL)** and the **residual volume (1700 mL)**, which does not correspond to a standard lung volume or capacity. - It does not logically relate to the definition of functional residual capacity. *2000 mL* - This value represents the sum of the **tidal volume (500 mL)** and the **expiratory reserve volume (1500 mL)**, which is incorrect for FRC. - This would represent the inspiratory capacity minus the inspiratory reserve volume, which is not a standard measurement used in pulmonary function testing. *2200 mL* - This value could be obtained by incorrectly adding the **tidal volume (500 mL)** and the **residual volume (1700 mL)**, which is not the correct formula for FRC. - This calculation represents a miscombination of lung volumes that does not correspond to any standard pulmonary capacity measurement. *3500 mL* - This value is the sum of the **tidal volume (500 mL)**, the **expiratory reserve volume (1500 mL)**, and the **residual volume (1700 mL)**. - This would represent the FRC plus the tidal volume, which is not a standard measurement and does not represent the functional residual capacity.

Pulmonary Flashcard 1 of 5

Question: Gross examination of pulmonary infarction due to PE reveals a hemorrhagic, _____-shaped infarct

Answer: wedge

Pulmonary Flashcard 2 of 5

Question: _____ pneumonia is characterized by diffuse interstitial infiltrates

Answer: Interstitial (atypical)

Pulmonary Flashcard 3 of 5

Question: Recovery of ARDS may be complicated by _____ due to loss of type II pneumocytes

Answer: interstitial fibrosis/scarring

Pulmonary Flashcard 4 of 5

Question: Hypersensitivity pneumonitis can lead to interstitial fibrosis and _____ lung disease with chronic exposure to the inhaled antigen

Answer: restrictive

Pulmonary Flashcard 5 of 5

Question: A Ghon complex is composed of a _____ and _____.

Answer: Ghon focus