Restrictive Pulmonary Disorders and Related Concepts

Obstructive vs. Restrictive Pulmonary Disorders

• Obstructive disorders: Air can get in, but difficulty getting it out.
• Restrictive disorders: Air can get out, but difficulty getting it in.

Restrictive Pulmonary Disorders

• Characterized by decreased lung expansion.
• Can result from:
  • Changes in lung tissue (parenchyma or interstitial tissue).
  • Changes in the pleura surrounding the lungs.
  • Problems with the chest wall.
  • Neuromuscular issues.

Lung Capacities and Volumes in Restrictive Disorders

• Opposite of obstructive disorders.
  • Decreased vital capacity.
  • Decreased lung capacity.
  • FRC and residual volume are lower.

Arterial Blood Gases

• Normal or decreased CO2 levels due to the ability to exhale.
• Decreased arterial O2 levels due to difficulty getting air in.

Pathophysiology of Restrictive Lung Disorders

• Damage to alveoli (epithelial cells) or capillary beds.
• Thickening of alveolar walls and interstitium.
• Repetitive damage leads to chronic inflammatory response.
• Collagen deposition to reinforce damaged tissue.
• Fibrosis restricts lung expansion, reducing compliance.

Inflammatory Process

• Causes damage to alveolar walls, capillary beds, and interstitium.
• Collagen deposition leads to loss of lung expandability.

Symptoms

• Progressive dyspnea with exercise.
• Desaturation during exercise.
• Nonproductive cough.
• End-expiratory crackles or rattles.
• Anorexia and weight loss due to increased work of breathing.
• Exercise does not increase cardiac output and can be harmful.

Treatment

• Smoking cessation (to reduce inflammatory triggers).
• Removal of environmental irritants.
• Anti-inflammatory agents to reduce inflammatory response.
• Immunosuppressive agents to control immune system response.

Hypersensitivity Pneumonitis (Extrinsic Allergic Alveolitis)

• Inflammation of the alveoli due to hypersensitivity to certain substances.
• More common in non-smokers.
• Can be an occupational disease (e.g., Farmer's Lung, Bird Fancier's Lung, Cheesemaker's Lung).

Specific Examples

• Farmer's Lung: Inhalation of particulate matter by farmers.
• Bird Fancier's Lung: Exposure to pet birds or chickens.
• Cheesemaker's Lung: Inhalation of particulate matter in cheesemaking.
• Grain Handler's Lung: Exposure to grain dust.
• Fish Meat Workers Lung: Exposure to pathogens in fish markets.
  Humidifier Lung: Exposure to bacteria, amoeba and fungi from humidifiers and evaporative coolers.

Mechanism

• Type III hypersensitivity reaction: Antigen-antibody complexes get trapped in alveolar walls, causing inflammation.
• Type IV hypersensitivity reaction: T-cell mediated, granulomatous inflammation.

Symptoms of Acute Hypersensitivity Pneumonitis

• Onset 4-6 hours after exposure, resolving within a day.
• Myalgias, weakness, sweating, chills, headache, malaise, lethargy.
• Dry cough, rapid breathing (tachypnea).
• Chest discomfort and dyspnea at rest.

Symptoms of Chronic Hypersensitivity Pneumonitis

• Persistent cough and dyspnea.
• Fatigue
• Pulmonary fibrosis leading to increased vascular resistance and cor pulmonale.
• X-rays show fibrosis in upper lobes.

Diagnosis

• Skin testing to identify triggering agents.
• Elevated WBCs (if around the antigen at testing).
• Drop in O2 saturation.
• Pulmonary function tests consistent with restrictive lung disorder.

Treatment

• Identify and remove the causative agent.
• Oral corticosteroids to reduce inflammation.

Occupational Lung Diseases (Pneumoconiosis)

• Caused by inhalation of gases or inorganic dust particles in the workplace.
• Atmospheric pollutants can exacerbate these conditions.
• Inorganic particles are non-processable by the body, causing damage.
• Greater and longer exposures worsen the consequences.

Mechanism of Damage

• Alveolar macrophages ingest particles but cannot process them.
• Macrophages eject the crystalline structures into the lung parenchyma or interstitium.
• Triggers inflammatory response.
• Deposition of collagenous fibers and crystalline structures in the lung parenchyma.
• Leads to fibrosis and loss of lung compliance.

Factors Influencing Occupational Lung Diseases

• Size and shape of inhaled particles.
• Amount and duration of exposure.
• Pre-existing lung disease (e.g., smoking, vaping).

Impact on Cilia

• Pollutants interfere with and paralyze cilia, impairing mucociliary clearance.
• Particles reach the alveoli and cannot be removed.

Macrophage Response

• Macrophages attempt to engulf particles, then exit and deposit them in bronchial walls and lung tissue which triggers inflammation.

Signs and Symptoms

• Often absent until the disease is well-established.
• Dyspnea and non-productive cough may develop after 10-20 years of exposure.
• Routine chest x-rays may reveal calcification and fibrosis.

Specific Example: Road Resurfacing Crews

• Inhalation of particulate matter without proper masks can lead to pneumoconiosis.

Late Features

• Respiratory failure and cor pulmonale.
• Chronic hypoxemia.
• Chest x-rays may be clear initially, with positive findings appearing later.
• Hypoxemia and hypercapnia.

Management

• Steroids to downregulate inflammation.
• Bronchodilators to increase airway diameter.
• O2 therapy, if necessary.
• Prevention is key, but it's challenging to advise job changes.

Atelectatic Disorders

• Atelectasis: Collapse of part or all of a lung.

ARDS (Acute Respiratory Distress Syndrome)

• High mortality rate (40-60%).
• Causes: Severe trauma, sepsis, aspiration of gastric acid.

Pathogenesis of ARDS

• Pulmonary edema due to inflammatory response (non-cardiogenic).
• Surfactant dilution leading to alveolar collapse (atelectasis).
• Hyaline membrane disease due to protein deposition.
• Fibrosis leading to restrictive lung disorder.

Inflammatory Response

• Edema, alveolar wall injury, capillary bed injury, interstitial tissue injury.
• Proteinaceous fluids deposit in alveoli, impairing ventilation.

Film Study Findings

• Fluffy, diffuse alveolar infiltrates (whiteout).

Early Signs and Symptoms

• Agitation, decreased O2 levels, rapid breathing, disorientation or irritability.
• Tachycardia and tachypnea.

Hallmark of ARDS

• Hypoxemia refractory to increased levels of supplemental O2.

White Out

• Cellular debris and edema in the interstitium and alveoli.
• Lung collapse (atelectasis).

Treatment of ARDS

• Mostly supportive, focusing on oxygenation and ventilation.
• Dialing down the inflammatory response and addressing the cause.

Positive End Expiratory Pressure (PEEP)

• Intubation with PEEP to keep airways open.
• Can cause the proliferation of oxide radicals, damaging alveolar membranes in the process.

Film Findings

• Snow-like appearance everywhere i.e. whiteout.

IRDS (Infant Respiratory Distress Syndrome)

• Infant analog of ARDS, also a hyaline membrane disease.
• Related to a dearth of surfactant in premature infants.
• Corticosteroid use reduces sequelae.

Risk Factors for IRDS

• Premature birth.
• Advanced gestational age (43+).
• Uncontrolled maternal diabetes.
• C-sections without antecedent labor.
• Perinatal asphyxia.
• Prior pregnancy with IRDS.
• RH factor incompatibility.

Management

• Immediate surfactant replacement (synthetic, bovine, or porcine).

Pathophysiology

• Lack of surfactant causes alveolar collapse.
• Increased pressure required to reopen collapsed alveoli.
• Atelectasis progresses, increasing pulmonary vascular resistance.
• This puts stress on the newborn heart because there is alveoli injury and an inflammatory response triggered.
• Protein deposition, ete.

Clinical Manifestations

• Cyanosis.
• Ribcage retractions.
• Nostril flaring.
• Shallow respirations.
• Hypotension and bradycardia.
• Edema and low body temperature.
• Tachypnea (60-120 respirations/minute).
• Frothy sputum and grunting sounds with expiration.
• Paradoxical chest respirations.

Amniocentesis Findings

• Lecithin to sphingomyelin ratio to assess lung maturity.
• Presence of phosphatidylglycerol.

Prevention and Treatment

• Glucocorticoid administration to mom before delivery.
• Exogenous surfactant administration.
• Ventilatory support (PEEP or forced inspiratory O2).
• Minimize handling and maintain neutral thermal environment to reduce metabolic demand.

Pleural Space Disorders

Pneumothorax

• Air enters the pleural space, disrupting negative pressure.
• Causes lung collapse on the affected side.

Types

• Primary pneumothorax: Spontaneous, often in tall, smoking males.
• Secondary pneumothorax: Due to underlying lung diseases (asthma, emphysema, cystic fibrosis, pneumonia)

Causes of Secondary Pneumothorax

• Lung diseases or other processes that increase respiratory pressure such as coughing resulting from coughing to clear mucus.
  *Structural abnormalities/blebs.

*Catamenial pneumothorax also exisits due to menstruation.

Tension Pneumothorax

• Due to pentration wound
• Can be cuased by high enough force being applied to the chest

Blebs

• Bleb ruptures and air comes rushing it causing the lung to collapse

Pathophysiology

• Ipsilateral lung collapse (same side).
• Contralateral tracheal and mediastinal shift (deviation to the opposite side).
• Impedes venous return and cardiac output.

Clinical Manifestations

• Small pneumothoraces (<20%) may be asymptomatic.
• Tachycardia, decreased breath sounds, hyperresonance.
• Sudden, sharp chest pain.
• Large spontaneous pneumothoraces are medical emergencies.

Diagnostic Findings

• Hemidiaphragm is decompressed.
• Chest xray shows no lung feilds. Can also indicate contralateral tracheal shift.
• Decreased arterial O2

Management

• Chest tube put in that rapidly reinfaltes the lung.
• Small collapses (< 15%) may not require treatment.
• Chemical pleuritis or laser treatment to create adhesions and seal blebs and strengthen the tissue at that location to prevent future bleb developement.
• Can do steriod medication to strengthen the tissue/membrane.

Pleural Effusion

• Excess fluid in the pleural cavity.
• Normal amount: 5-15 mL (smaller people) to 50-65 mL(larger people).
• Excess fluid prevents movement and causes friction to the two membranes i.e. parietal and visceral plerua causing inflammation.

Types of Fluid

• Transudates and Exudates exisit within the pleural caivty and keep drawing fluid out of surrounding tissues.
• Empyema: Pus-filled pleural effusion due to bacterial infection.
• Results in an enormous osmotic pressure gradient which keeps fluid in the area/cavity.

Pathophysiology

• Sharp pain is experienced when breathing
• Leads to restrictive lung disorder with minimal breath/lung sounds due to water.
• Decrease in fluid travelling from lungs to surrounding locations.

Clinical features with pleural Effusion

• A person is usually asymptomatic if it's less than 300 milliliters of fluid.
• Decreased breath sounds and dullness to percussion.
• Decreased tactile fremitus.
• Contralateral tracheal shift

Diagnostic Measurements

• Thoracentesis. (Puncture to determine if ther'e fluid)
• CT scan

Treatment

• In adults, a closed chest tube is inserted.
• In pediatric patients, this is a controversial approach as the risk of puncturing the heart is extremely high, and could be fatal.