Respiratory Made Simple For NLE NRE Step 1

1. Spirometry (Pulmonary Function Test – PFT)

1. Tidal Volume (TV):

• Volume of air inhaled or exhaled with each breath.
• Normal Value: 500 mL.

2. Inspiratory Reserve Volume (IRV):

• The amount of air that can be inhaled after a normal breath.
• Normal Value: 2.5 L (Note: You mentioned 25 L, which seems to be a typo. Typical value is around 2-3 L).

3. Expiratory Reserve Volume (ERV):

• The amount of air that can be exhaled after a normal exhalation.
• Normal Value: 1.5 L.

4. Residual Volume (RV):

• The amount of air remaining in the lungs after a full exhalation.
• Normal Value: 1.5 L.

5. Lung Volumes and Capacities

1. Vital Capacity (VC):

• The total amount of air that can be exhaled after taking a deep breath.
  • Formula: VC = TV + IRV + ERV + RV.

2. Functional Residual Capacity (FRC):

• The volume of air remaining in the lungs after a normal exhalation.
  • Formula: FRC = RV + ERV.

2. Obstructive Lung Disease (ABCD)

• Asthma
• Bronchiectasis
• COPD (Chronic Obstructive Pulmonary Disease)
• Obstructive Lung Disease (general term)

These conditions typically involve increased airway resistance leading to difficulty exhaling, which is evident in reduced FEV1 (forced expiratory volume in 1 second) and FEV1/FVC ratio (forced vital capacity).

3. Asthma

Chronic, inflammatory, reversible airway obstruction.

1. Genetic Association:

• Atopy (genetic predisposition to develop allergic diseases such as asthma).

2. Pathophysiology:

• HSR-1 (Type I Hypersensitivity Reaction): Mediated by histamine, leading to inflammation and bronchoconstriction.

3. Clinical Presentation (P/C):

• Dyspnea: Difficulty breathing.
• Shortness of Breath (SOB): More common in childhood.
• Tachypnea: Increased respiratory rate, typically observed in adulthood.
• Expiratory Wheeze: Audible wheezing on exhalation, a hallmark of asthma.
• Can occur in both childhood and adulthood.

4. Triggers:

• Pollen.
• Seasonal changes.
• Perfume (allergic triggers).

5. Diagnostic Tests:

• FEV1/FVC ratio: Less than 70%, indicating obstructive lung disease.
• Methacholine challenge test: Positive in asthma, indicating airway hyperresponsiveness.
• IgE levels: Elevated, suggesting an allergic component to asthma.

6. Management of Asthma

• Bronchodilators:
  • Beta-2 Agonists:
    • SABA (Short-Acting Beta Agonists):
      • Salbutamol, Albuterol.
      • Action: Rapid relief of acute symptoms by relaxing bronchial muscles.
    • LABA (Long-Acting Beta Agonists):
      • Salmeterol, Formoterol.
      • Side Effects: Tremor (a common side effect of beta-2 agonists).
  • M3 Antagonists:
    • Ipratropium, Tiotropium.
    • Action: Reduce mucus production and help in bronchodilation.
  • PDE Inhibitors:
    • Theophylline.
    • Side Effects: Cardiotoxic and neurotoxic effects, including arrhythmias and seizures, especially at high doses.

4. Kartagener Syndrome (A type of Primary Ciliary Dyskinesia)

1. Dextrocardia.
2. Bronchiectasis.
3. Sinusitis.

5. COPD (Chronic Obstructive Pulmonary Disease)

6. Pleural Pathology

7. Pneumothorax

8. Lung Cancer

• Leading Cause of Mortality:
  Lung cancer is the leading cause of cancer-related mortality.
• Risk Factors:
  • Age: Common in individuals 50 years and older.
  • Smoker: Strongly associated with a smoking history.
  • Hemoptysis: Coughing up blood.
  • Weight loss: Common symptom.

1. Ectopic Hormone Production in Lung Cancer:

1. ACTH (Cushing Syndrome):
   • Seen in small cell lung cancer (SCLC), leading to Cushing syndrome.
2. ADH (SIADH):
   • Seen in small cell lung cancer (SCLC), leading to Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH).
3. Cyclic Citrullinated Antibody (CCB):
   • Associated with Lambert-Eaton Myasthenic Syndrome (LEMS) and Myasthenia Gravis (MG), often found in small cell lung cancer (SCLC).

2. Non-Small Cell Lung Cancer (NSCLC):

1. PTH-rP (Parathyroid Hormone-related Protein):
   • Causes hypercalcemia in squamous cell carcinoma of the lung.
   • Typically occurs in non-smokers.
2. Serotonin Increase:
   • Seen in carcinoid tumors, which cause carcinoid syndrome (flushing, diarrhea, and wheezing).

Here are other materials for NLE NRE step 1

9. Sleep Apnea

Sleep apnea refers to the transient stoppage of breathing during sleep, which disrupts sleep quality.

Types of Sleep Apnea:

1. Obstructive Sleep Apnea (OSA):
   • Airway Obstruction: Blockage of the upper airway during sleep, leading to interrupted breathing.
   • Causes:
     • Adenoid and tonsillitis.
     • Improper posture during sleep.
     • Obesity.
2. Central Sleep Apnea:
   • Etiology: Specific causes related to the central nervous system (e.g., brainstem dysfunction).

9. Systemic Sarcoidosis

• Clinical Features:
  • Erythema nodosum: Painful red nodules, typically on the shins.
  • Hilar lymphadenopathy: Enlargement of lymph nodes in the chest.
• Diagnosis:
  • Best Initial Test: Chest X-ray to assess for hilar lymphadenopathy.
  • Confirmatory Test: CT-guided biopsy for tissue analysis.
• Diagnosis:
  • Systemic Sarcoidosis.
• Treatment:
  • Best Treatment: Corticosteroids (e.g., prednisone).
• Lofgren Syndrome:
  • A form of sarcoidosis characterized by:
    • Fever.
    • Arthritis.
    • Erythema nodosum.