NRE Step 1: Respiratory Made Simple – Pass with Precision

How We Breathe (Spirometry/Lung Capacity)

When we breathe in and out normally, that’s called “Tidal Volume” (about 500ml of air).
We can breathe in extra air if we try (Inspiratory Reserve Volume – IRV).
We can breathe out extra air after a normal breath (Expiratory Reserve Volume – ERV).
Some air always stays in our lungs (Residual Volume – RV).
Lung Capacity: This is how much air our lungs can hold or move.
- Vital Capacity: All the air we can breathe in and out if we try our hardest.
- Functional Residual Capacity: The air left in our lungs after a normal breath out.

2. Breathing Problems (Obstructive Lung Disease)

These are problems where it’s hard to get air out of the lungs.
Examples include: Asthma, Bronchiectasis, COPD, and blockages from things stuck in the airway.

3. Asthma

Asthma is a long-lasting problem where the airways (the tubes that carry air) get inflamed and narrow, making it hard to breathe. It can get better with treatment.
It’s often linked to allergies.
Signs of Asthma: Trouble breathing, shortness of breath, a whistling sound when breathing out (wheezing).
It can be triggered by things like pollen, perfumes, or changes in seasons.
Testing for Asthma: Doctors can do a test to see how much air you can blow out. If a certain ratio (FEV1/FVC) is less than 70%, it might be asthma. Another test uses a medicine called Methacholine.
Treating Asthma:
- Bronchodilators: Medicines that open up the airways.
  - SABA (Short-Acting Beta-Agonists): Like Salbutamol and Albutamol, work quickly.
  - LABA (Long-Acting Beta-Agonists): Like Salmeterol and Formoterol, work for a longer time.
  - Side Effects: Can cause shakiness.
  - Other medicines like Ipratropium and Tiotropium can also help.
  - Theophylline is another medicine, but it can be bad for the heart or brain.

4. Bronchiectasis

This is a problem where the airways become wide and damaged.
Signs: Trouble breathing, shortness of breath, chest tightness, and lots of mucus when coughing.
Sometimes it’s linked to other problems like Kartagener’s Syndrome (where organs might be on the wrong side of the body, like the heart being on the right – Dextrocardia) and sinus infections (Sinusitis).

5. COPD (Chronic Obstructive Pulmonary Disease)

COPD is a long-lasting, serious problem where the airways are blocked and don’t get better.
Two main types:
- Chronic Bronchitis: This is when you have a cough that produces mucus for at least 3 months a year, for two years in a row. It’s often caused by smoking. People with this are sometimes called “blue bloaters” because they might have bluish lips and swelling.
- Emphysema: This is when the tiny air sacs in the lungs get damaged and lose their stretchiness. It’s also often caused by smoking. People with this are sometimes called “pink puffers” because they breathe with pursed lips and might have a barrel-shaped chest.

6. Problems with the Lung Covering (Pleural Pathologies)

The lungs are covered by a thin layer called the pleura.
Fluid in the Lung Covering (Pleural Effusion): If there’s fluid, tapping on the chest might sound dull. X-rays might show blurred areas. If the fluid has a lot of protein, it’s called an “exudative effusion”.
Air in the Lung Covering (Pneumothorax): This is when air gets into the space around the lung.
- If there’s a lot of air, it can push the windpipe (trachea) to one side.
- Tapping on the chest might sound very loud and hollow.
- If it keeps happening, doctors might put a tube in the chest.

7. Lung Cancer

Lung cancer is a leading cause of death.
It’s often seen in older people who smoke.
Signs: Coughing up blood, weight loss.
Some lung cancers can make chemicals that affect other parts of the body, like causing Cushing syndrome or SIADH (a problem with water balance).
Small cell lung cancer can be linked to Lambert-Eaton Myasthenic Syndrome (a muscle weakness problem).
Carcinoid tumors in the lung can make too much serotonin.

8. Stopping Breathing While Sleeping (Sleep Apnea)

Sleep apnea is when you stop breathing for short times while you’re asleep, which makes your sleep not restful.
Types:
- Obstructive Sleep Apnea (OSA): This is when something blocks your airway while you sleep, like large tonsils or adenoids, or sleeping in a bad position. Obesity can also cause this.
- Central Sleep Apnea: This is when the brain doesn’t send the right signals to breathe.

9. Sarcoidosis

This is a disease that can affect different parts of the body, including the lungs.
Signs: Cough, trouble breathing, shortness of breath, and red bumps on the shins (Erythema Nodosum).
Diagnosis: Doctors might do a chest X-ray (which can show swollen lymph nodes near the lungs) or a biopsy (taking a small piece of tissue).
Treatment: Corticosteroids are often used.
Lofgren’s Syndrome: A specific type of sarcoidosis that includes fever and joint pain.

10. Lung Problems from Dust (Pneumoconiosis)

These are lung problems caused by breathing in certain dusts.
Asbestosis: Caused by breathing in asbestos, often from working with tiles or demolishing ships. Can lead to lung cancer or mesothelioma (a serious cancer of the lung lining).
Silicosis: Caused by breathing in silica dust, common in mineworkers or people who work with pottery. X-rays can show “snowstorm appearance” and “eggshell calcification”. It increases the risk of tuberculosis (TB).

What is asthma?
It is a long-term (chronic) lung problem. It causes breathing trouble because the airways get narrow and inflamed.

1. For Long-Term (Chronic) Asthma:

A. Beta (β) Agonists – Help relax airway muscles.

SABA (Short-Acting Beta Agonist):
Inhaler that works quickly.
LABA (Long-Acting Beta Agonist):
Inhaler that works for a long time.
➤ Can cause shaking (tremors) and side effects (S/E).

B. M3 Antagonist:
Blocks M3 receptor, which helps relax airways.
Side effects:

C. Theophylline:
Relaxes airway muscles.

D. Leukotriene Receptor Inhibitor:

Mast Cell Stabilizer:
- Example: Nedocromil Sodium or Glycate
Omalizumab:
- Stops IgE from sticking to mast cells.
- This helps prevent allergic asthma.

Antibody	Used For
Omalizumab	Asthma
Palivizumab	Bronchiolitis
Denosumab	Osteoporosis
Eculizumab	PNH (Paroxysmal Nocturnal Hemoglobinuria)
Trastuzumab	HER2+ breast cancer