Pulmonary and Asthma Quiz

Lung Volume Terminology

• FEV1: Forced Expiratory Volume in 1 second. The amount of air forcefully exhaled in one second after a maximal inspiration.
• FVC: Forced Vital Capacity. The total volume of air that can be maximally exhaled following a maximal inspiration.
• FEV1/FVC Ratio: Ratio used to distinguish between obstructive and restrictive lung diseases.
• TLC: Total Lung Capacity. The maximum amount of air that can be inhaled after a normal exhalation.
• TV: Tidal Volume. The amount of air inhaled and exhaled during normal breathing.
• IRV: Inspiratory Reserve Volume. The additional amount of air that can be inhaled after a normal inhalation.
• IC: Inspiratory Capacity. The total amount of air in the lungs following maximal inspiration.
• ERV: Expiratory Reserve Volume. The additional amount of air that can be exhaled after a normal exhalation.
• FRC: Functional Residual Capacity. The volume of air remaining in the lungs after a normal exhalation.
• RV: Residual Volume. The volume of air remaining in the lungs after a maximal exhalation.
• DLCO: Diffusion capacity of the lungs for carbon monoxide. A measure of how well gas exchange is occurring across the pulmonary capillaries and reflects the extent of gas exchange.

Obstructive vs Restrictive Lung Disease

• Obstructive Pattern: Characterized by difficulty exhaling air due to narrowed airways. Examples include asthma and chronic obstructive pulmonary disease (COPD).
  • FEV1: Decreased
  • FVC: Decreased
  • FEV1/FVC Ratio: Decreased (<70%)
  • TLC: Usually normal or increased (due to air trapping)
  • IC: and IRV: Normal
  • ERV: Normal
  • FRC: Usually increased (due to air trapping)
  • DLCO: Usually normal or slightly decreased (variable depending on specific cause)
• Restrictive Pattern: Characterized by a reduced lung capacity due to problems with lung expansion. Examples include pulmonary fibrosis and certain chest wall conditions.
  • FEV1: Decreased
  • FVC: Decreased
  • FEV1/FVC Ratio: Normal or slightly increased
  • TLC: Decreased
  • IC and IRV: Decreased
  • ERV: Decreased
  • FRC: Decreased
  • DLCO: Decreased

Flow-Volume Loops

• Obstructive: Expiratory portion of the flow-volume loop is scooped out/concave. This is because of airflow obstruction, which reduces the flow rate throughout exhalation.Inspiratory flow rate is relatively preserved, but overall size of the loop is reduced due to less volume in the lungs on maximum inspiration.
• Restrictive: Loop is smaller and more symmetric; overall size of the loop is reduced due to a decreased volume in the lungs on maximum inspiration.

Shunt vs Dead Space

• Shunt: Reduced ventilation relative to perfusion. Shunt is characterized by a reduction in the amount of oxygenated blood that reaches the lungs. The most HY scenarios on USMLE involve abnormal blood flow bypassing the alveoli entirely. Often indicated by a decreased arterial oxygen level despite normal/adequate inspiratory capacity.
• Dead Space: Increased ventilation relative to perfusion. Dead space is characterized by air entering the lungs without delivering oxygen to the blood. It is a HY point that USMLE likes to focus on cases of pulmonary embolism and alveolar dead space, which refers to regions of lung tissue receiving ventilation but not oxygen exchange. In these cases, the arterial oxygen level is also decreased.

Alveolar-Arterial (A-a) Gradient

• High A-a gradient: The difference between the expected partial pressure of oxygen in the alveoli and the actual partial pressure of oxygen in the arteries is high. This often signifies a problem with gas exchange in the lungs. Typical reasons for a hyperinflated A-a gradient on USMLE are reduced ventilation due to hypoventilation or pulmonary pathologies.
• Normal A-a gradient: The difference between the expected and actual partial pressure of oxygen in the alveoli and arteries appears normal, typically between 5-10 mmHg. Often indicative of normal ventilation, with sufficient oxygen delivery.

HY Pulmonary/Respiratory Tract Cancers

• Small Cell Bronchogenic Carcinoma: Typically occurs centrally in the lung, presents as a small basophilic cell, and is strongly associated with smoking. A HY point for the USMLE is that it is associated with paraneoplastic syndromes (SIADH, Cushing syndrome, Lambert-Eaton syndrome...).
• Squamous Cell Carcinoma: Arises centrally in the lung, frequently associated with smoking. Noteworthy for potential cavitation (cavity/hole) formation.
• Adenocarcinoma: This type of lung cancer is typically peripheral in location and is more common in female nonsmokers in USMLE vignettes. Associated with high yield presentations, but not necessarily central lungs (such as hilar or mediastinal masses).

HY Pulmonary Conditions Related to Trauma

• Atelectasis: Collapsed lung tissue, often a concern post-surgery or trauma. Causes reduced breath sounds, dullness to percussion, and decreased tactile fremitus. Can be caused by obstruction distal to lung tissue leading to loss of perfusion.
• Flail Chest: Result of multiple rib fractures, leading to paradoxical chest wall movement.
• Pulmonary Contusion: Bruising of lung tissue, often from blunt trauma.
• Diaphragmatic Rupture: Common complication of trauma, often indicated by diaphragmatic movement on CXR.
• Pneumothorax: Air in the pleural space. Classified as either simple, tension or open. Often involves decreased breath sounds and hyperresonance to percussion.
• Pleural Effusion: Fluid in the pleural space, typically associated with increased lung disease and heart failure. Often noted on X-ray as dullness to percussion.

HY Pulmonary Conditions Related to Infections

• Pneumonia: Lung infection (bacterial, viral, or fungal). Possible symptoms include fever, cough, shortness of breath, and chest pain.
• **Pleurisy:**Inflammation of the pleura, the membranous lining of the lungs. Pain typically worsens with deep breaths.
• **Pneumonia:**Lung infection may be caused by a variety of factors, presenting in many different ways depending on the specific pathogen.
• **Empyema:**Pus in the pleural space (purulent pleural effusion); a complication of pneumonia.

HY Pulmonary Conditions Related to Autoimmune Diseases

• Systemic Sclerosis (Scleroderma): Chronic autoimmune disease leading to widespread fibrosis and hardening of tissues, frequently involving the lungs. Characterized by limited or diffuse forms. It is noteworthy for its association with pulmonary hypertension, so high yield for both Step 1 and 2CK forms.
• Sarcoidosis: Chronic inflammatory disease characterized by the presence of non-caseating granulomas, predominantly affecting the lungs. Hypersensitivity/autoimmune response. Noteworthy for high yield presentations including an elevated vitamin D level, even though it may be present within normal range in USMLE vignettes.

HY Pulmonary Conditions Related to Vascular Issues

• Pulmonary Hypertension: Increased blood pressure in the pulmonary arteries, often a consequence of other underlying conditions (like PPH).
• Pulmonary Edema: Fluid buildup in the lungs. A high yield presentation that can occur in a number of different contexts (like heart failure or infections like pneumonia).
• ARDS (Acute Respiratory Distress Syndrome): Often occurring as a secondary complication to other medical complications. Noteworthy for cases that occur <6 hours post-transfusion, with the cause TRALI (transfusion related acute lung injury).
• TRALI (Transfusion-related acute lung injury): Non-cardiogenic pulmonary edema, occurring within six hours of transfusion.
• TACO (Transfusion-associated circulatory overload): Cardiogenic pulmonary edema, occurring more than six hours after transfusion.

Lung Cancers

• Bronchogenic Carcinoma: A general term for cancers arising in the bronchi, leading to problems with oxygen exchange.
• Small Cell Lung Cancer: A rapidly growing type of lung cancer most frequently central, associated with poor prognosis.
• Squamous Cell Carcinoma: Highly associated with a smoking history.
• Adenocarcinoma: Also frequently associated with smoking.

Other Respiratory Conditions

• Bronchiectasis: Chronic dilation of the bronchi. Can result from infections or other chronic conditions.
• Asthma: Characterized by reversible airway obstruction.
• Epiglottitis: Severe, potentially life-threatening inflammation of the epiglottis.
• Bacterial Tracheitis: Infection of the trachea.
• Pertussis (Whooping Cough): Highly contagious bacterial infection characterized by cough that can be severe and persistent.
• Pleurisy/Pleuritis: Pain in the chest that worsens during breathing.
• Pneumonia: Infection leading to inflammation of the alveoli.
• Croup: Swelling of the larynx and trachea, commonly seen in children.
• Tuberculosis (TB): Infectious disease caused by a type of bacterium.
• Chronic Obstructive Pulmonary Disease (COPD): Characterized by chronic airway obstruction and difficulties with airflow. A commonly seen presentation is with increased CO2 levels.
• Hot Tub Lung: Caused by inhaling contaminated water.
• Foreign Body Aspiration: Objects obstructing airways.

Congenital or Childhood Respiratory Conditions

• Congenital Diaphragmatic Hernia: Bowel or other abdominal organs herniate into the chest cavity; this is a critical condition for infants causing difficulty breathing.
• Tracheoesophageal Fistula (TEF): An abnormal connection between the trachea and esophagus.
• Choanal Atresia: Congenital closure of the nasal airway passages.

Test your knowledge on pulmonary conditions, asthma management, and related medications. This quiz covers key concepts such as the effects of CO2 levels, mechanisms of drugs like Bosentan, and the impact of corticosteroids. Enhance your understanding of respiratory diseases and their treatments.