Medicine Marrow Pg 191-200 (Pulmonology)
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Medicine Marrow Pg 191-200 (Pulmonology)

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Questions and Answers

Which of the following methods can measure Residual Volume (RV)?

  • Both B and C (correct)
  • Spirometry
  • Open-circuit nitrogen washout method
  • Total body plethysmography

    • Forced Vital Capacity (FVC) is normally less than 4.5 L.

    False

    Name one example of an obstructive lung disease.

    Chronic bronchitis

    The maximum air exhaled in the first second is known as the ______.

    <p>FEV1</p> Signup and view all the answers

    What is the primary indicator of obstructive lung disease on spirometry?

    <p>FEV1/FVC &lt; 0.7</p> Signup and view all the answers

    In COPD, there is a loss of elastic recoil leading to driving pressure being greater than airway pressure.

    <p>False</p> Signup and view all the answers

    Match the following terms to their correct descriptions:

    <p>COPD = A group of lung diseases that block airflow Myasthenia gravis = A neuromuscular disorder affecting respiratory muscle strength Pulmonary HTN = High blood pressure in the lungs Kyphoscoliosis = A chest wall disorder affecting lung expansion</p> Signup and view all the answers

    What medication is typically administered during bronchodilator reversibility testing?

    <p>Salbutamol or Ipratropium</p> Signup and view all the answers

    What happens to the diffusion lung capacity of carbon monoxide (DLCO) in patients with interstitial lung disease (ILD)?

    <p>Decreases</p> Signup and view all the answers

    In the phase of copd characterized by __________, patients experience significant air trapping.

    <p>Phase II</p> Signup and view all the answers

    Match the following indicators with their corresponding phases in obstructive lung disease:

    <p>Phase I = Hyperinflation Phase II = Air trapping Varied FEV1 = Decreased in both phases Reversibility = Indicates bronchial asthma</p> Signup and view all the answers

    In extraparenchymal restrictive lung disease, the diffusion capacity (DLCO) is normal.

    <p>True</p> Signup and view all the answers

    What happens to the forced vital capacity (FVC) in the progression of intraparenchymal restrictive lung disease?

    <p>Decreases</p> Signup and view all the answers

    In restrictive lung disease, the forced expiratory volume in one second (FEV1) is generally _____ or increases.

    <p>normal</p> Signup and view all the answers

    Match the following disorders with their characteristics:

    <p>Myasthenia Gravis = Pure inspiratory disorders with increased RV, TLC Kyphoscoliosis = Inspiratory and expiratory disorders with normal RV Vascular Lung Disease = Normal FEV1, FVC with abnormal DLCO Interstitial Lung Disease = Intraparenchymal disease with decreased DLCO</p> Signup and view all the answers

    What characterizes the expiration phase of breathing?

    <p>It is a passive process.</p> Signup and view all the answers

    Obstructive lung diseases decrease static compliance of the lungs.

    <p>False</p> Signup and view all the answers

    What role does surfactant play in inspiration?

    <p>It reduces surface tension.</p> Signup and view all the answers

    In restrictive lung diseases, the curve shifts _____ and to the right due to increased collagen.

    <p>down</p> Signup and view all the answers

    Match the lung disease type to its characteristic effect on pressure-volume curves:

    <p>Obstructive diseases = Shift up and to the left Restrictive diseases = Shift down and to the right COPD = Increased static compliance ILD = Decreased static compliance</p> Signup and view all the answers

    Which type of pneumocyte is responsible for surfactant production?

    <p>Type II Pneumocyte</p> Signup and view all the answers

    Type I pneumocytes are prone to oxidative damage.

    <p>True</p> Signup and view all the answers

    What is the major component of pulmonary surfactant?

    <p>Lipoprotein</p> Signup and view all the answers

    Type II pneumocytes are involved in _______ post-injury.

    <p>repair</p> Signup and view all the answers

    Match the following surfactant proteins with their functions:

    <p>Surfactant Protein A = Involved in innate immunity Surfactant Protein B = Facilitates surfactant spreading Surfactant Protein C = Stabilizes alveoli Surfactant Protein D = Involved in innate immunity</p> Signup and view all the answers

    Which factor contributes to a decrease in airway resistance according to Poiseuille's law?

    <p>Increased radius</p> Signup and view all the answers

    Airway resistance is highest in the early generations of airways.

    <p>True</p> Signup and view all the answers

    What is the Reynolds number used to determine in airflow?

    <p>Type of flow (laminar, transitional, turbulent)</p> Signup and view all the answers

    The flow type in the trachea and bronchi is classified as __________ flow.

    <p>turbulent</p> Signup and view all the answers

    What is the primary factor that determines transpulmonary pressure (TPP)?

    <p>Intrapleural pressure</p> Signup and view all the answers

    Match the following Reynolds numbers to their corresponding flow types:

    <blockquote> <p>4000 = Turbulent flow 4000 - 2000 = Transitional flow &lt;2000 = Laminar flow</p> </blockquote> Signup and view all the answers

    Intrapleural pressure equals intrapulmonary pressure during a pneumothorax.

    <p>True</p> Signup and view all the answers

    What is the formula for calculating static compliance?

    <p>Δv / Δp</p> Signup and view all the answers

    The total transpulmonary pressure (TPP) equals the intrapleural pressure minus the ______.

    <p>atmospheric pressure</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>Total Lung Capacity (TLC) = Maximum amount of air the lungs can hold Functional Residual Capacity (FRC) = Volume of air remaining in the lungs after a normal expiration Static Compliance = Lung volume per unit change in pressure Intrapleural Pressure = Pressure within the pleural cavity</p> Signup and view all the answers

    What is the normal tidal volume (VT) in the lungs?

    <p>500 mL</p> Signup and view all the answers

    Intrapleural pressure is always positive during forceful expiration.

    <p>True</p> Signup and view all the answers

    What is the relationship between tidal volume and transpulmonary pressure as per Boyle's law?

    <p>Tidal volume inversely relates to transpulmonary pressure.</p> Signup and view all the answers

    During inspiration, the intra alveolar pressure is ______ mmHg.

    <p>-1</p> Signup and view all the answers

    Match the types of pressure with their descriptions:

    <p>Intrapleural pressure = Pressure in pleura Intraalveolar pressure = Pressure within the alveoli Transpulmonary pressure = Difference between intraalveolar pressure and intrapleural pressure Pleural pressure = Pressure exerted by fluid in the pleural cavity</p> Signup and view all the answers

    Which of the following factors contributes to a decrease in dynamic compliance?

    <p>Foreign body obstruction</p> Signup and view all the answers

    Total lung capacity (TLC) is associated with a negative directed force during inflation.

    <p>False</p> Signup and view all the answers

    What is the sum of the End-Expiratory Residual Pressure (ERP) of the lung and chest wall referred to as?

    <p>Total ERP</p> Signup and view all the answers

    Atelectasis is an example of a condition that results in a fall in dynamic ______.

    <p>compliance</p> Signup and view all the answers

    Match the following lung volumes with their corresponding effects on inflation:

    <p>Residual volume = Easy to inflate, -ve forces directed outwards Functional residual capacity (FRC) = Zero, easy to inflate Total lung capacity (TLC) = Difficult to inflate, +ve forces directed downwards</p> Signup and view all the answers

    What is the amount of air flowing in and out of the lungs during normal quiet breathing called?

    <p>Tidal volume</p> Signup and view all the answers

    The Functional Residual Capacity (FRC) is the amount of air remaining in the lungs after normal expiration.

    <p>True</p> Signup and view all the answers

    What is the formula for calculating Inspiratory Capacity (IC)?

    <p>TV + IRV</p> Signup and view all the answers

    The amount of air remaining in the lungs at the end of forceful maximum expiration is called ______.

    <p>residual volume</p> Signup and view all the answers

    Match the lung capacities with their definitions:

    <p>Inspiratory Capacity = Amount of air inspired after normal expiration Forced Vital Capacity = Amount of air expired after forceful inspiration Functional Residual Capacity = Amount of air remaining after normal expiration Total Lung Capacity = Maximum amount of air the lungs can hold</p> Signup and view all the answers

    Study Notes

    Restrictive Lung Disease (ILD)

    • ILD is characterized by fibrosis, leading to impaired diffusion and ventilation.
    • Initially, defective diffusion from alveoli into capillaries results in a decreased diffusion lung capacity of carbon monoxide (DLCO).
    • Forced vital capacity (FVC) remains normal in early stages.
    • As the disease progresses, both diffusion and ventilation are significantly reduced.
      • FVC, FEV1, RV, and TLC are all decreased.
      • DLCO remains significantly reduced.

    Types of Restrictive Lung Diseases

    • Intraparenchymal diseases:
      • Primarily diffusion disorders (e.g., ILD)
      • Characterized by a significantly decreased DLCO.
    • Extraparenchymal diseases:
      • Primarily ventilation disorders with a significantly decreased FVC.
      • Diffusion remains normal with a normal DLCO.
      • RV remains normal.
    • Pure inspiratory (Neuromuscular) disorders:
      • For example, Myasthenia Gravis
      • Characterized by increased RV and TLC.
    • Inspiratory + Expiratory disorders:
      • Examples include Kyphoscoliosis
      • RV remains normal
      • TLC may vary.
    • Vascular Lung Disease:
      • FEV1 and FVC remain normal
      • DLCO is abnormal.

    Obstructive Lung Disease (Emphysema)

    • Emphysema is characterized by a loss of elastic recoil pressure in the lungs. This results in a driving pressure lower than the airway pressure.
    • Bronchioles collapse due to the lack of cartilage, leading to dynamic compression of airways.
    • The inability to exhale air out leads to air trapping.

    Stages of Emphysema

    • Phase I: Hyperinflation
    • Phase II: Air Trapping

    Spirometry in Obstructive Lung Disease

    • FEV1/FVC ratio < 0.7.
    • Bronchodilator reversibility testing helps differentiate between asthma and other obstructive lung diseases.

    Spirometry

    • FVC (Forced Vital Capacity): 4.5 L normally expired in 5-6 seconds.
    • FEV1 (Forced Expiratory Volume in 1 second): Amount of air exhaled within the first second.
    • In normal individuals, FEV1 ≥ 80% of FVC (4 L).

    Measuring Residual Volume (RV)

    • RV cannot be measured with a spirometer.
    • Functional Residual Capacity (FRC) and Total lung capacity (TLC) cannot be measured with a spirometer.
    • RV is measured using:
      • Total body plethysmography
      • Closed-circuit helium method
      • Open-circuit nitrogen washout method

    Spirometry Uses

    • Measuring volume and flow to plot:
      • Volume-Time graph
      • Flow-volume graph

    Spirometry Disadvantages

    • Physically demanding procedure

    Spirometry Procedure

    • Maximal inspiration followed by a continuous exhalation for at least 15 seconds or minimum 6 seconds.
    • Not performed after medical emergencies, strenuous physical activity or smoking.

    Volume-Time Graph

    • FVC (Forced Vital Capacity) is the total volume of air exhaled during the test.
    • FEV1 is the volume of air exhaled in the first second.

    Lung Diseases

    • Obstructive diseases:

      • COPD (Chronic Obstructive Pulmonary Disease):
        • Chronic bronchitis
        • Emphysema
        • Small airway disease
        • Bronchial asthma
        • Cystic fibrosis
        • Bronchiolitis
        • Bronchiectasis

    • Restrictive diseases:

      • ILD (Interstitial Lung Disease)
      • Neuromuscular:
        • Myasthenia gravis
        • Guillain-Barre syndrome (GBS)
      • Chest wall disorders:
        • Kyphoscoliosis
        • Obesity
        • Ankylosing spondylitis
      • Vascular:
        • Pulmonary HTN
        • Pulmonary thromboembolism

    Hysteresis Loop

    • The ΔV/ΔP curve for inspiration and expiration differs due to the involvement of different forces.
    • Inspiration:
      • Occurs against resistance.
      • Surface tension is overcome by surfactant.
      • Elastic recoil pressure.
    • Expiration:
      • Passive process; does not require extra force.
      • Elastic recoil pressure (ERP) of the lung.

    Elastic Recoil Pressure (ERP)

    • ERP is due to elastin (elastic force) and collagen (tensile strength).
    • ERP changes in airway diseases.

    Obstructive Diseases (e.g. COPD, Emphysema)

    • Increased static compliance.
    • Curve shifts up and to the left on the pressure-volume graph.
    • Loss of elastin leads to a decrease in ERP.

    Restrictive Diseases (e.g. ILD)

    • Decreased static compliance.
    • Curve shifts down and to the right on the pressure-volume graph.
    • Fibrosis leads to an increase in collagen and ERP, making it more difficult to inflate the lung.

    Alveolar Cells

    • There are three main types of alveolar cells:
      • Type I Pneumocyte (95%)
      • Type II Pneumocyte (5%)
      • Pulmonary Alveolar Macrophage (PAM)

    Type I Pneumocyte

    • Non-dividing flat squamous cells.
    • Prone to oxidative damage.
    • Bleomycin causes injury to Type I pneumocytes.
    • Markers: Aquaporin-5, Caveolin-1, Carboxypeptidase m.

    Type II Pneumocyte

    • Cuboidal (rounded) cells.
    • Involved in repair after injury and surfactant production.
    • Bleomycin causes hyperplasia of type II pneumocytes.
    • Markers: Surfactant proteins A, B, C, D.

    Surfactant

    • Function:

      • Reduces surface tension.
      • Prevents fluid accumulation (pulmonary edema).

    • Synthesis:

      • Lamellar Bodies, storage bodies in type II pneumocytes, produce surfactants.

    • Components:

      • Phospholipids (major component), with Lecithin (DPPC) exceeding Sphingomyelin.
      • Surfactant proteins (A, B, C, D) with A and D involved in innate immunity.

    • Regulation of production:

      • Increased by: Steroids, Thyroid hormone
      • Decreased by: Insulin

    Other

    • GM-CSF clears excess surfactant, antibodies against GM-CSF cause a condition called pulmonary alveolar proteinosis.
    • Substance P is a bronchoconstrictor.
    • Dipalmitoyl phosphatidylcholine (DPPC) is the major component of surfactant.
    • Maximum bronchoconstriction occurs around 6 am, while bronchodilatation peaks around 6 pm.
    • Beractant is used in Hyaline membrane disease (HMD) / Fetal Respiratory Distress Syndrome.

    Clinical Physiology of Lungs

    • Tidal volume (VT): The volume of air moving in and out of lungs with each breath. Normal VT is approximately 500 mL.
    • Boyle's law: Tidal volume is inversely proportional to transpulmonary pressure (TPP).

    Pressures in Respiratory Physiology

    • Intrapleural pressure: Pressure within the pleural cavity; typically negative.
    • Intraalveolar pressure (IAP): Pressure within the alveoli; zero at rest, negative during inspiration, and positive during expiration.
    • Transpulmonary pressure (TPP): Difference between intraalveolar pressure and intrapleural pressure (TPP = IAP - Intrapleural pressure).

    Inspiration

    • An active process involving contraction of respiratory muscles and the diaphragm.
    • Chest wall expands, leading to a decrease in intrapleural pressure.

    Expiration

    • A passive process driven by the elastic recoil of the lungs.
    • Intrapleural pressure becomes less negative or even slightly positive.

    Airway Resistance and Airflow

    • From trachea to alveoli:

      • Airway diameter decreases.
      • Total cross-sectional area increases.
      • Velocity of airflow decreases.
      • Turbulence decreases.

    • Determinants of airway resistance:

      • Ohm's law: Flow is inversely proportional to resistance.
      • Poiseuille's law: Resistance is proportional to viscosity and length, and inversely proportional to the radius of the airway to the power of four.

    • Maximum radius leads to least resistance and maximum flow:

      • Trachea: Highest velocity (turbulence) of flow.
      • Alveoli: Lowest velocity (laminar flow).

    • Area of maximum resistance:

      • Generations 5, 6, 7 (bronchi to terminal bronchioles) due to parallel arrangement of small airways.

    • Maximum cross-sectional area increases, leading to low resistance to airflow.

    Reynolds' Number (Re)

    • Re = arvd/η (where "arvd" is a variable concerning factors affecting Reynolds number, η is viscosity)
    • Re proportional to velocity (v).

    Flow Types and Reynolds Numbers

    Re Type of Flow Areas
    > 4000 Turbulent flow Trachea, Bronchi
    4000 - 2000 Transitional flow Respiratory bronchioles
    < 2000 Laminar flow Alveolar duct, alveoli

    Transpulmonary Pressure (TPP)

    • Total TPP = TPP of lung + TPP of chest wall.
    • TPP of chest wall = Intrapleural pressure - atmospheric pressure.
    • Total TPP = IAP - atmospheric pressure.

    Lung to Thorax Linkage

    • Intrapleural fluid cohesiveness: Water molecules attract each other, resisting being pulled apart, contributing to negative intrapleural pressure.

    Compliance

    • Static compliance: The change in lung volume per unit change in pressure; approximately 200 mL/cm H₂O.
    • Maximal compliance: Occurs at mid-range pressure.
    • Static compliance at tidal volume: Represents lung inflation per unit change in transpulmonary pressure (TPP)
      • Static compliance = Δv / Δp
      • ΔP = TPP

    Dynamic Compliance

    • Dynamic compliance is a measure of the lung's ability to inflate and deflate during breathing.
    • Dynamic compliance is affected by both static compliance and airway resistance.
    • Static and dynamic compliance typically change together.

    Examples of Reduced Dynamic Compliance

    • Foreign body
    • Kink in endotracheal tube (ET tube)
    • Intrathoracic obstruction
    • Pulmonary edema
    • Consolidation
    • Atelectasis
    • Pneumothorax

    Elastic Recoil Pressure (ERP) of the Respiratory System

    • Total ERP = ERP (Lung) + ERP (Chest wall)

    • ERP changes due to combined effects of the lung and chest wall, and varying lung volumes.

    • Changes in ERP:

    At Contributed by Resulting Effect/Direction of Forces Image Inflation of Lung
    Residual volume Chest wall -ve (Directed outwards) Easy
    Functional residual capacity (FRC) Chest wall + Lung Zero (Tendency of lung collapse counterbalanced by chest wall expansion) Easy
    Total lung capacity (TLC) Chest wall + Lung +ve (Both forces directed downwards) Difficult

    Pulmonary Function Tests

    Lung Volumes and Capacities

    • Lung Volumes:
    Volume Definition
    Tidal volume (TV) (5-7 mL/kg) Volume of air flowing in and out of lungs during normal quiet breathing.
    Inspiratory Reserve Volume (IRV) Amount of air inspired with maximum force after tidal inspiration.
    Expiratory Reserve Volume (ERV) Amount of air expired with maximum force after tidal expiration.
    Residual volume (RV) Amount of air remaining in lungs at the end of forceful maximum expiration.
    • Lung Capacities:
    Capacity Formula Definition
    Inspiratory Capacity (IC) 3.5 L TV + IRV Amount of air inspired with maximum force after normal expiration.
    Forced vital Capacity (FVC) 4.5 L 0.5 L + 3 L + 1 L Amount of air expired with maximum force after forceful inspiration.
    Functional Residual Capacity (FRC) 2.2 L ERV + RV Amount of air remaining in lung after a normal expiration.
    Total Lung Capacity (TLC) 5.7 L FVC + RV
    • At FRC, the elastic recoil pressure on the system is zero, with the lung's recoil being counterbalanced by the chest wall's expansion.

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    Explore the complexities of restrictive lung diseases, particularly interstitial lung disease (ILD). This quiz covers key characteristics, types of restrictive lung diseases, and how they affect lung capacity and function. Test your understanding of diffusion and ventilation impairments associated with these conditions.

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