543 Week 2 Pulm Diagnostics 1 May 6

Pulmonary Function Testing

  • Types of Pulmonary Function Tests:

    • Spirometry: Measures lung volumes.

    • Diffusion capacity.

    • Arterial Blood Gases (ABGs): Assesses respiratory alkalosis or acidosis.

    • Methacholine challenge test: Evaluates asthma.

    • Exercise testing: Assesses pulmonary or cardiac capacity.

Indications for Pulmonary Function Testing

  • Severity of disease.

  • Identification of disease (restrictive or obstructive).

  • Disability assessment (e.g., VA disability claims related to Agent Orange exposure).

  • Operative risk assessment before major surgery with lengthy anesthesia.

  • Assessment of therapy effectiveness (e.g., inhalers).

  • Assessment of potential lung toxicity of a therapy (e.g., amiodarone).

  • Early-stage lung rejection in lung transplants.

Contraindications for Pulmonary Function Tests

  • Uncooperative patients.

  • Recent pneumothorax (within 4-6 weeks).

  • Recent heart attack or myocardial infarction (wait a few weeks).

  • Recent abdominal, thoracic, or eye surgery (due to increased intrathoracic pressure).

  • Recent sinus surgery (PFT would be inaccurate).

Spirometry

  • Key Acronyms:

    • Forced Vital Capacity (FVC): Volume of air exhaled after deep inspiration.

    • Forced Expiratory Volume in one second (FEV1): Volume of air exhaled in the first second.

    • FEV1/FVC Ratio: Defines obstruction.

  • FVC: Volume of air exhaled after deep inspiration overall.

  • Vital Capacity: Volume of air slowly exhaled after deep inspiration (counted over three seconds).

  • FEV1: Volume of air exhaled in the first second.

  • FEV1/FVCFEV1/FVC: Ratio defines obstruction.

Factors Affecting Spirometry

  • Coaching: Effectively guiding the patient through the test.

  • Height Measurement: Essential for accurate calculations.

  • Exhalation Duration: Should be a maximum of six seconds.

  • Trials: Generally three trials with good effort and reproducibility.

  • Reference Values: Established for ages 8 to 80.

Spirometry with Bronchodilator

  • Assess baseline numbers.

  • Administer a bronchodilator.

  • Repeat the test to see if there's a change.

  • A positive response may warrant starting someone on a new medication.

  • No response doesn't rule out the benefit of being on a chronic bronchodilator.

Interpreting Spirometry

  • Normal values based on gender, age, height, and race.

  • Values expressed as a percent predicted.

  • Greater than 80% of predicted is generally considered normal.

Patterns on Pulmonary Function Testing

  • Two Main Categories:

    • Obstructive

    • Restrictive

Obstructive Diseases

  • Asthma

  • Chronic bronchitis

  • Emphysema

  • Bronchiolitis

  • Bronchiectasis

Spirometry in Obstructive Disease

  • FVC can be normal or decreased.

  • Reduced FEV1/FVCFEV1/FVC ratio helps define obstruction.

  • FEV1FEV1 less than 1 is associated with disabling dyspnea.

  • Can be reversible after administering a bronchodilator (e.g., albuterol).

GOLD Guidelines

  • Global Initiative for Chronic Obstructive Lung Disease (GOLD).

  • Mild: FEV1 at 80% predicted.

  • Moderate: FEV1 at 50% predicted.

  • Severe: FEV1 at 30% predicted.

  • Very Severe: FEV1 less than 30% predicted.
    *Note: GINA guidelines (2024) are the most current ones used to help how to treat asthma.

Endobronchial Valves

  • An option to treat shortness of breath in patients with emphysema.

  • One-way valves are placed in smaller bronchioles to create back pressure.

  • 30% chance of pneumothorax.

  • It does not cure the patient's lung disease but helps with symptoms.

Asthma

  • Considered a reversible airway obstruction.

  • Defined as a decreased FEV1/FVCFEV1/FVC ratio.

  • 12% improvement after bronchodilator is substantial.

Restrictive Diseases

  • Two Types:

    • Intrinsic

    • Extrinsic

Spirometry in Restrictive Diseases

  • Decreased FVC and FEV1.

  • FEV1/FVCFEV1/FVC ratio can be normal or increased (not decreased).

  • Need lung volumes and diffusion capacity measurements.

Lung Volume Measurements

  • Overall capacity measured first, then inspiratory capacity, then expiratory reserve volume.

Obstructive lung disease has increased TLC RV over TLC ratio.

Restrictive have a decreased TLC, RV, and FRC.

Obesity can decrease capacity and expiration.

Diffusion Capacity

  • Diffusion from the alveolus up into the pulmonary capillary.

  • Carbon monoxide is used as a measure of diffusing ability (single breath or rebreathing test).

  • Carbon monoxide has a higher affinity for hemoglobin than oxygen.

Extrinsic vs. Intrinsic Restriction

  • Extrinsic: Volume is decreased.

  • Intrinsic: Volume is decreased.

  • DLCO (diffusion capacity) assesses how well oxygen is diffusing across into the capillaries.

Examples of Intrinsic Restriction: Pulmonary fibrosis, interstitial lung disease.

Examples of Extrinsic Restriction: Obesity, drug-induced.

Bronchoscopy

  • Types:

    • Fiber Optic: Diagnostic, can be therapeutic (bronchial washing), conscious sedation, quick recovery.

    • Rigid Bronchoscopy: Therapeutic (tumor staging, resection), general anesthesia, can't go as far.

Risks with Bronchoscopy

  • Vocal cord injury (laryngitis).

  • Sinusitis.

  • Bronchitis.

  • Pneumonia.

  • Bleeding.

  • Pneumothorax.

  • Bronchospasm.

  • Aspiration.

Contraindications

  • Severe hypoxemia.

  • Bleeding disorders.

  • Cardiovascular instability.

  • Status asthmaticus.

  • Marked hypercapnia.

Why Perform Bronchoscopy

  • Visualization.

  • Bronchial washings or lavage (BAL).

  • Brushing.

  • Endobronchial needle aspiration (EBUS).

  • Transbronchial lung biopsy.

  • Balloon dilation for strictures.

  • Tumor debulking (Lung transplant).

Chest CTs (Computed Tomography)

Why do Chest CTs

  • Better define something seen on a chest X-ray.

  • Pulmonary embolus.

  • Adenocarcinoma (lung cancer).

  • Mediastinal process (mediastinoscopy).

  • Cancer staging.

  • Thymoma.

  • Fibrosing tissue.

  • High-resolution CT scan for lung tissue: Emphysema, interstitial lung disease, lung nodules, parenchymal abnormalities.

  • Invasive procedure staging.

  • Extrapulmonary structures (adrenal glands).

Accidental catch of lung cancer or pulmonary embolus on asymptomatic patients..

Techniques

  • Standard CT Scan: Slice thickness 3-10 mm, with or without contrast, for abnormal chest X-rays, cancer staging, follow-up on mets, pleural or mediastinal abnormalities, empyema.

  • Low-Dose CT Scans: Screening tools, lung nodule clinics, less radiation, infection follow-up, post-transplant.

  • CT Angiography: With contrast, improves definition of mediastinum, lymph nodes, pulmonary/systemic vasculature, rule out pulmonary embolus, aortic dissection/aneurysm, AV malformations, superior vena cava syndrome.

  • High Resolution: Thinner slices, more detailed, generally without contrast, for interstitial lung disease, pulmonary fibrosis.

Examples of CT Scans

  • Emphysema: degradation back of the lungs, and it produces black hols.

  • Lower Lobe vs Upper Lobe: where will you find tubercolosis.