LSD -NOV-DEC 2025 AU QP ANS

 

NOV/DEC 2025

OBT356-Lifestyle Diseases

Question & Answers

1. Define Lifestyle Disease.
A lifestyle disease is a chronic disease mainly caused or influenced by unhealthy lifestyle habits such as poor diet, physical inactivity, smoking, alcohol consumption, and stress.
Examples: Diabetes, obesity, cardiovascular diseases.

2. What is obesity?
Obesity is a condition in which excessive body fat accumulates to a level that may affect health. It is commonly assessed using Body Mass Index (BMI).

3. Define cancer.
Cancer is a disease in which abnormal cells grow and divide uncontrollably, forming a tumor or invading surrounding tissues and sometimes spreading to other parts of the body.

4. Mention different types of cancer.
Major types of cancer include:

• Breast cancer
• Lung cancer
• Prostate cancer
• Colorectal cancer
• Skin cancer
• Blood cancer (Leukemia)

5. Name some cardiovascular diseases.
Some cardiovascular diseases are:

• Coronary artery disease
• Heart attack
• Stroke
• Hypertension
• Heart failure

6. Mention any two causes of cardiovascular disease.
Two major causes/risk factors are:

1. Unhealthy diet and high cholesterol
2. Smoking and tobacco use

7. Define Diabetes.
Diabetes is a chronic metabolic disease in which the blood glucose level becomes abnormally high due to insufficient insulin production, ineffective use of insulin, or both.

8. Mention the different types of diabetes.
The major types of diabetes are:

1. Type 1 Diabetes
2. Type 2 Diabetes
3. Gestational Diabetes

9. What is chronic lung disease?
Chronic lung disease refers to long-term diseases that affect the lungs and make breathing difficult.
Examples: Chronic Obstructive Pulmonary Disease (COPD), asthma, and pulmonary fibrosis.

10. Mention the causes of asthma.
Asthma may be triggered by:

• Dust and pollen
• Smoke and air pollution
• Allergens
• Respiratory infections
• Exercise and cold air

PART -B

11. (a) Explain various risk factors of lifestyle diseases with suitable examples.

  Introduction

Lifestyle diseases are chronic diseases that are mainly associated with unhealthy habits and living conditions. They develop gradually and include obesity, diabetes, cardiovascular diseases, cancer and chronic respiratory diseases

Major Risk Factors 1. Unhealthy Diet Excess intake of saturated fats, trans fats, salt, sugar and processed foods increases the risk of obesity, diabetes and cardiovascular diseases. Example: Regular consumption of fast food can increase cholesterol and body weight.   2. Physical Inactivity Lack of regular exercise reduces energy expenditure and promotes obesity, hypertension and diabetes. Example: A person who spends most of the day sitting and does not exercise has a higher risk of Type 2 diabetes.  3. Tobacco Smoking Smoking damages the lungs and blood vessels and is a major risk factor for lung cancer, COPD and cardiovascular diseases.  4. Alcohol Consumption Excessive alcohol consumption can cause liver disease, hypertension, cardiovascular problems and certain cancers.  5. Obesity and Overweight Excess body fat increases the risk of diabetes, hypertension, heart disease and some cancers.

6. Stress Long-term psychological stress can contribute to hypertension, sleep disorders, unhealthy eating habits and cardiovascular diseases.  7. Lack of Sleep Insufficient or irregular sleep may increase the risk of obesity, diabetes and cardiovascular diseases.  8. Environmental Pollution Air pollution and exposure to harmful chemicals can increase the risk of respiratory diseases and lung cancer.  9. Genetic Factors Some individuals have an inherited tendency to develop certain diseases. Example: A family history of diabetes may increase the risk of developing Type 2 diabetes.  10. Age and Gender The risk of many chronic diseases increases with age. Certain diseases may also have different risks in males and females.

 

 

 11. (b) Describe the preventive measures to avoid lifestyle diseases.

  Introduction

 Prevention is an important method of reducing the occurrence and complications of lifestyle diseases. Healthy lifestyle practices can prevent many chronic diseases.

 

Preventive Measures  1. Balanced Diet  * Eat vegetables, fruits and whole grains. * Include adequate protein and dietary fibre. * Reduce saturated fat, trans fat, salt and added sugar. * Avoid excessive processed and junk foods.  2. Regular Physical Activity  * Perform regular aerobic exercises such as walking, cycling and swimming. * Include muscle-strengthening exercises. * Avoid prolonged sitting.  3. Maintain Healthy Body Weight Maintaining a healthy BMI reduces the risk of diabetes, hypertension and cardiovascular diseases.  4. Avoid Tobacco Smoking and other tobacco products should be completely avoided because they increase the risk of cancer, heart disease and lung disease.  5. Limit Alcohol Avoid excessive alcohol consumption to reduce the risk of liver, cardiovascular and other chronic diseases.

6. Stress Management Stress can be controlled through:  * Yoga * Meditation * Relaxation techniques * Adequate rest * Recreational activities  7. Adequate Sleep Adults should maintain a regular sleep schedule and obtain sufficient quality sleep.  8. Regular Health Check-ups Periodic measurement of:  * Blood pressure * Blood glucose * Blood cholesterol * Body weight and BMI  helps detect diseases at an early stage.  9. Environmental Protection Avoid exposure to tobacco smoke, polluted air, industrial chemicals and other harmful substances.  10. Health Education Awareness programmes should educate people about healthy food, exercise, personal hygiene and disease prevention.

 

12. (a) Write in detail about diagnosis and treatment of lung cancer.

  Introduction

 Lung cancer is a malignant disease in which abnormal cells grow uncontrollably in the lung tissue. Smoking is the major risk factor, although non-smokers can also develop lung cancer.

  Types of Lung Cancer

 1. Non-Small Cell Lung Cancer (NSCLC)

2. Small Cell Lung Cancer (SCLC)

 

Diagnosis 1. Medical History and Physical Examination The physician assesses smoking history, occupational exposure, cough, chest pain, breathlessness and weight loss.  2. Chest X-ray It may show an abnormal mass or shadow in the lung.  3. CT Scan CT provides detailed images of the lungs and helps determine the size and location of a tumor.  4. PET Scan A PET scan can help identify metabolically active cancer and detect spread to other organs.  5. Bronchoscopy A bronchoscope is passed through the airways to examine the lungs and obtain tissue samples.  6. Biopsy A tissue sample is examined under a microscope to confirm cancer.  7. Sputum Cytology Sputum may be examined for abnormal cancer cells in selected cases.  8. Molecular/Genetic Testing Tumor tissue may be tested for specific genetic changes to determine whether targeted therapy may be useful.

Treatment  1. Surgery Surgical removal of the tumor or affected part of the lung may be performed when the cancer is localized and operable.  2. Chemotherapy Anti-cancer drugs are used to destroy or control cancer cells.  3. Radiation Therapy High-energy radiation is used to destroy cancer cells.  4. Targeted Therapy Specific medicines target genetic or molecular changes present in some lung cancers.  5. Immunotherapy Medicines stimulate the immune system to recognize and attack cancer cells.  6. Palliative Treatment For advanced cancer, treatment may focus on controlling symptoms such as pain, breathlessness and cough and improving quality of life.   Prevention  * Avoid smoking and tobacco. * Avoid second-hand smoke. * Reduce occupational exposure to harmful substances. * Maintain a healthy lifestyle. * Appropriate high-risk individuals should discuss lung-cancer screening with a healthcare professional.

 

12. (b) Write the causes, diagnosis and treatment of mouth cancer.

 Introduction

Mouth cancer, also called oral cancer, is the uncontrolled growth of abnormal cells in parts of the mouth such as the lips, tongue, gums, inner cheeks and floor of the mouth.

  Causes and Risk Factors

1. Tobacco Use

Smoking cigarettes, cigars and using smokeless tobacco significantly increases the risk.

2. Alcohol Consumption

Excessive alcohol use increases the risk, particularly when combined with tobacco. 

3. Human Papillomavirus (HPV)

Certain HPV infections are associated with cancers of the mouth and throat.

4. Poor Oral Hygiene

Poor oral health may contribute to chronic irritation and oral disease.

5. Excessive Sun Exposure

Long-term ultraviolet exposure increases the risk of cancer of the lip.

6. Age and Genetic Factors

Risk generally increases with age, and family history may contribute.

Symptoms * Non-healing mouth ulcer * White or red patch * Lump or thickening * Persistent mouth pain * Difficulty chewing or swallowing * Unexplained bleeding * Loose teeth * Persistent sore throat or hoarseness

Diagnosis 1. Oral Examination The dentist or doctor examines the mouth, tongue, gums and throat. 2. Biopsy A tissue sample from the suspicious area is examined to confirm cancer. 3. Imaging Tests * CT scan * MRI * PET scan

 

 

Treatment 1. Surgery The tumor and, when necessary, nearby lymph nodes may be surgically removed. 2. Radiation Therapy High-energy radiation is used to destroy cancer cells. 3. Chemotherapy Anti-cancer medicines are used, particularly in selected advanced cases or in combination with other treatments. 4. Targeted Therapy and Immunotherapy These may be used for selected advanced cancers depending on tumor characteristics.

Prevention   * Avoid tobacco. * Limit alcohol. * Maintain good oral hygiene. * Obtain regular dental examinations. * Protect the lips from excessive sunlight.

 

13. (a) Write a detailed note on Coronary Artery Disease.

  Introduction

 Coronary Artery Disease (CAD) is a condition in which the coronary arteries become narrowed or blocked, reducing blood flow and oxygen supply to the heart muscle. It is commonly caused by atherosclerosis

Causes and Risk Factors  1. High blood cholesterol 2. High blood pressure 3. Smoking 4. Diabetes 5. Obesity 6. Physical inactivity 7. Unhealthy diet 8. Family history 9. Increasing age 10. Chronic stress

Pathogenesis  Fatty substances, cholesterol and other materials accumulate inside the coronary artery wall and form plaque  The sequence is:  Endothelial damage → Fat deposition → Plaque formation → Narrowing of artery → Reduced blood flow → Ischemia  If a plaque ruptures and a blood clot forms, the artery may become completely blocked, resulting in a heart attack (myocardial infarction)

 

Symptoms  * Chest pain or pressure * Pain spreading to the arm, shoulder, neck or jaw * Shortness of breath * Fatigue * Sweating * Dizziness * Nausea Diagnosis 1. ECG – Detects electrical abnormalities of the heart.  2. Echocardiography – Assesses heart structure and pumping function.

3. Blood Tests – Cholesterol, glucose and cardiac biomarkers may be evaluated.   4. Exercise Stress Test – Assesses the heart during physical activity.   5. CT Coronary Angiography – Provides images of the coronary arteries.   6. Coronary Angiography – Invasive imaging used to identify significant coronary artery narrowing or blockage.

 

Treatment  1. Lifestyle Modification  * Healthy diet * Regular physical activity * Weight management * Smoking cessation * Stress reduction  2. Medicines Depending on the patient, medicines may include:  * Statins * Antiplatelet drugs * Beta-blockers * ACE inhibitors/ARBs * Nitrates

3. Angioplasty and Stenting A narrowed coronary artery may be opened using a balloon catheter and a stent may be placed to maintain blood flow.  4. Coronary Artery Bypass Grafting (CABG) A new route for blood flow is created around severely blocked coronary arteries.   Prevention  Control blood pressure, blood sugar and cholesterol, maintain healthy weight, exercise regularly and avoid tobacco.

 

13. (b) Explain how Electrocardiograph and Echocardiograph are useful in heart diseases.

#1. Electrocardiograph (ECG)  An electrocardiograph is an instrument used to record the electrical activity of the heart. The recorded graph is called an electrocardiogram (ECG)   Working  Electrodes are placed on the patient's chest and limbs. They detect the electrical signals produced during heart activity.   Uses of ECG  1. Detection of Arrhythmia It can identify abnormal heart rhythms.  2. Heart Attack ECG changes can indicate current or previous myocardial infarction.  3. Coronary Artery Disease Certain ECG changes may indicate reduced blood supply to the heart muscle.  4. Heart Rate It measures the heart rate and rhythm.  5. Conduction Abnormalities It can detect problems such as heart blocks.  6. Monitoring ECG is useful for monitoring patients during treatment and surgery.

#2. Echocardiograph  An echocardiograph uses high-frequency ultrasound waves to produce images of the heart.   Working An ultrasound transducer is placed on the chest. Ultrasound waves are transmitted into the body and reflected from heart structures. The echoes are converted into images.   Uses of Echocardiography  1. Heart Chamber Examination It shows the size and shape of heart chambers.  2. Valve Diseases It can detect abnormal opening or closing of heart valves.  3. Pumping Function It measures heart function, including ejection fraction  4. Congenital Heart Disease It can identify structural abnormalities present from birth.  5. Fluid Around the Heart It can detect pericardial effusion.  6. Blood Flow Doppler echocardiography evaluates the direction and velocity of blood flow.

  Difference

ECG	Echocardiograph
Records electrical activity	Produces images of the heart
Detects rhythm abnormalities	Detects structural abnormalities
Uses electrodes	Uses ultrasound
Useful for arrhythmias and heart attack	Useful for valves and pumping function

  14. (a) Explain various methods to regulate the blood glucose level.

  Introduction

 Blood glucose must be maintained within a healthy range to provide energy to cells and prevent complications. Regulation occurs through hormones, diet, physical activity and medical treatment

  1. Insulin

 Insulin is produced by the β-cells of the pancreas It lowers blood glucose by:

 * Increasing glucose uptake by cells

* Promoting glycogen formation

* Reducing glucose production by the liver

  2. Glucagon

 Glucagon is produced by pancreatic α-cells It increases blood glucose by stimulating:

 * Breakdown of glycogen

* Production of glucose by the liver

  3. Balanced Diet

 Blood glucose can be better controlled by:

 * Eating high-fibre foods

* Choosing whole grains

* Eating vegetables

* Limiting added sugars

* Controlling portion sizes

  4. Regular Exercise

 Physical activity increases glucose uptake by muscles and improves insulin sensitivity.

 Examples:

 * Walking

* Cycling

* Swimming

* Aerobic exercise

* Strength training

  5. Weight Management

Maintaining a healthy body weight improves insulin sensitivity and helps prevent Type 2 diabetes.

  6. Oral Anti-Diabetic Medicines

 Depending on the type and needs of the patient, medicines such as metformin, sulfonylureas, DPP-4 inhibitors, SGLT2 inhibitors and GLP-1 receptor agonists may be used.

  7. Insulin Therapy

 Insulin injections are essential for Type 1 diabetes and may also be required for some people with Type 2 diabetes.

  8. Blood Glucose Monitoring

 Regular monitoring helps determine whether blood glucose is within the target range and guides treatment.

  9. Stress and Sleep Management

 Adequate sleep and stress reduction can support better glucose control.

 14. (b) What are the complications of Diabetes? Add a note on weight control and BMI.

 #Complications of Diabetes

 Diabetes can affect blood vessels, nerves and several organs when blood glucose remains uncontrolled for a long period.

  1. Cardiovascular Complications

Diabetes increases the risk of:

* Coronary artery disease

* Heart attack

* Stroke

* Hypertension

  2. Diabetic Neuropathy

High blood glucose can damage nerves, causing:

* Numbness

* Tingling

* Burning sensation

* Loss of sensation

  3. Diabetic Retinopathy

Damage to retinal blood vessels may cause impaired vision and, in severe cases, blindness.

  4. Diabetic Kidney Disease

Long-term diabetes can damage the kidneys and may eventually lead to kidney failure.

  5. Diabetic Foot Problems

Reduced sensation and poor circulation can lead to foot ulcers, infection and delayed wound healing.

  6. Infections

People with poorly controlled diabetes may be more susceptible to certain infections.

  7. Acute Complications

Severe hypoglycaemia and diabetic ketoacidosis are important acute complications.

 

#Weight Control Maintaining healthy body weight is important in diabetes management.  Methods * Eat a balanced diet. * Control portion size. * Exercise regularly. * Reduce sugary drinks and processed foods. * Monitor body weight regularly. * Maintain adequate sleep.

#Body Mass Index (BMI) BMI is a simple measure used to relate body weight to height. Formula: BMI = Weight in kg / (Height in metres2  General Adult BMI Categories | BMI         | Category      | | ----------- | ------------- | | Below 18.5  | Underweight   | | 18.5–24.9   | Normal weight | | 25.0–29.9   | Overweight    | | 30 or above | Obesity       |   BMI is a screening measure, not a direct measure of body fat.

 

15. (a) Write a detailed note on Chronic Obstructive Pulmonary Disease (COPD).

  Introduction

 Chronic Obstructive Pulmonary Disease (COPD) is a chronic lung disease characterized by persistent respiratory symptoms and airflow limitation. The major cause is long-term exposure to tobacco smoke

  Major Types

 1. Chronic Bronchitis

Long-term inflammation of the bronchi with excessive mucus production and chronic cough.

 2. Emphysema

Damage to the walls of the alveoli, resulting in reduced surface area for gas exchange.

Causes and Risk Factors  1. Cigarette smoking 2. Second-hand smoke 3. Indoor and outdoor air pollution 4. Occupational dust and chemicals 5. Repeated respiratory infections 6. Genetic factors such as alpha-1 antitrypsin deficiency

Symptoms  * Chronic cough * Excess sputum production * Shortness of breath * Wheezing * Chest tightness * Fatigue * Frequent respiratory infections

 

Diagnosis  1. Spirometry It is the main test for detecting persistent airflow limitation.  2. Chest X-ray Helps assess lung changes and exclude other conditions.  3. CT Scan Provides detailed images of lung structure.  4. Pulse Oximetry Measures blood oxygen saturation.  5. Arterial Blood Gas Analysis May be used in selected patients to assess oxygen and carbon dioxide levels.

Treatment  1. Smoking Cessation The most important intervention for smokers with COPD.  2. Bronchodilators These medicines relax airway muscles and improve airflow.  3. Inhaled Corticosteroids Used in selected patients, particularly those with frequent exacerbations or specific clinical features.  4. Pulmonary Rehabilitation Includes exercise training, education and breathing strategies.  5. Oxygen Therapy Long-term oxygen may be prescribed for selected patients with severe chronic hypoxaemia. 6. Vaccination Recommended vaccinations can help reduce respiratory infections.  7. Surgery In selected severe cases, procedures such as lung volume reduction or lung transplantation may be considered.

 Prevention

* Stop smoking.

* Avoid second-hand smoke.

* Reduce exposure to occupational dust and chemicals.

* Improve indoor air quality.

* Use appropriate protective equipment.

 

15. (b) Explain the causes of respiratory diseases and explain their diagnosis.

  Introduction

 Respiratory diseases affect the airways, lungs and respiratory muscles. They may be caused by infections, smoking, pollution, allergens, occupational exposure and other factors.

 

#Causes of Respiratory Diseases   1. Smoking Smoking damages airway and lung tissues and can cause COPD and lung cancer.   2. Air Pollution Dust, smoke and harmful gases can irritate the respiratory system.   3. Allergens Dust mites, pollen, animal dander and mould can trigger asthma and allergic respiratory problems.   4. Infections Viruses, bacteria and fungi can cause respiratory infections such as pneumonia and tuberculosis.   5. Occupational Exposure Long-term exposure to asbestos, silica, coal dust and industrial chemicals may cause occupational lung diseases.   6. Genetic Factors Some respiratory diseases have a genetic component.   7. Lifestyle and Environmental Factors Poor ventilation, passive smoking and unhealthy living conditions can increase respiratory problems.

#Diagnosis of Respiratory Diseases  1. Medical History The physician asks about: * Cough * Sputum * Breathlessness * Wheezing * Chest pain * Smoking history * Occupational exposure  2. Physical Examination The doctor examines breathing pattern and listens to lung sounds using a stethoscope.   3. Chest X-ray Used to identify pneumonia, tumors and other structural abnormalities.   4. CT Scan Provides detailed images of lung tissues and airways.   5. Spirometry Measures the amount and speed of air inhaled and exhaled. It is particularly useful in asthma and COPD.   6. Pulse Oximetry Measures oxygen saturation in the blood.   7. Arterial Blood Gas Test Measures oxygen, carbon dioxide and acid-base status in arterial blood.   8. Sputum Examination Sputum may be examined for bacteria, tuberculosis organisms or abnormal cells.

 

PART C – 15 MARKS

 16. (a) Explain in detail about causes, diagnosis and treatment of skin cancer.

  Introduction

 Skin cancer is the abnormal and uncontrolled growth of cells in the skin. The major types include basal cell carcinoma, squamous cell carcinoma and melanoma

 #Causes and Risk Factors

  1. Ultraviolet (UV) Radiation

Excessive exposure to sunlight and artificial UV radiation is the major risk factor.

  2. Fair Skin

People with lighter skin have less natural protection from UV radiation.

  3. History of Sunburn

Repeated severe sunburns increase the risk of skin cancer.

  4. Artificial UV Exposure

Frequent use of tanning beds increases UV exposure.

  5. Family History

A family history of melanoma can increase risk.

  6. Multiple or Atypical Moles

Certain types and numbers of moles can increase melanoma risk.

  7. Weakened Immune System

Immunosuppression can increase the risk of certain skin cancers.

  8. Previous Skin Cancer

A previous skin cancer increases the likelihood of developing another.

 

#Signs and Symptoms A suspicious skin lesion may show changes in: * Size * Shape * Colour * Border * Surface

For melanoma, the ABCDE warning signs are: A – Asymmetry B – Border irregularity C – Colour variation D – Diameter increase E – Evolving lesion

 

Other warning signs include a sore that does not heal, bleeding or a rapidly growing skin lesion.

 

#Diagnosis   1. Physical Examination The entire skin surface may be examined for suspicious lesions.   2. Dermoscopy A dermatoscope provides magnified visualization of skin structures.   3. Skin Biopsy A suspicious lesion is removed partly or completely and examined under a microscope. Biopsy confirms the diagnosis.   4. Imaging CT, MRI or PET imaging may be used for selected advanced cancers to determine spread.   5. Lymph Node Assessment For selected melanomas, sentinel lymph node biopsy may help determine whether cancer has spread to nearby lymph nodes.

#Treatment   1. Surgical Excision The cancerous lesion is removed with a margin of healthy tissue.   2. Mohs Surgery Mohs micrographic surgery may be used for selected skin cancers, especially in areas where tissue preservation is important.   3. Cryotherapy Liquid nitrogen may be used for selected superficial precancerous or cancerous lesions.   4. Radiation Therapy Radiation may be used when surgery is unsuitable or in selected advanced cases.   5. Topical Treatment Certain superficial skin cancers may be treated with prescription topical medicines.   6. Immunotherapy Immunotherapy is an important treatment option for selected advanced skin cancers, especially melanoma.   7. Targeted Therapy For melanoma with specific mutations, targeted medicines may be used.

  Prevention

* Avoid excessive sun exposure.

* Use broad-spectrum sunscreen.

* Wear protective clothing.

* Avoid tanning beds.

* Examine the skin regularly.

* Consult a healthcare professional for changing or suspicious lesions.

 

16. (b) Describe various Pulmonary Function Tests along with procedure and their interpretation.

  Introduction

Pulmonary Function Tests (PFTs) are a group of tests used to assess how well the lungs work. They evaluate lung volume, airflow and gas exchange.

 

#1. Spirometry Spirometry is the most commonly used pulmonary function test.    Procedure 1. The patient sits comfortably. 2. A nose clip may be applied. 3. The patient breathes through a mouthpiece connected to a spirometer. 4. The patient takes a deep breath and then exhales as forcefully and completely as possible. 5. The test is repeated to obtain reliable measurements.  Important Parameters FVC – Forced Vital Capacity Maximum volume of air forcibly exhaled after a maximum inspiration. FEV₁ – Forced Expiratory Volume in 1 second Volume exhaled during the first second of forced expiration. FEV₁/FVC Ratio Helps identify airflow obstruction. Interpretation * Obstructive pattern: FEV₁ is reduced and the FEV₁/FVC ratio is reduced. * Restrictive pattern: FVC is reduced while the FEV₁/FVC ratio is often normal or increased; restriction is confirmed by measuring total lung capacity. Examples: COPD and asthma → obstructive pattern. Pulmonary fibrosis → restrictive pattern.   2. Lung Volume Measurement Lung volumes include: * Tidal Volume (TV) * Inspiratory Reserve Volume (IRV) * Expiratory Reserve Volume (ERV) * Residual Volume (RV) * Total Lung Capacity (TLC) Procedure Lung volumes that cannot be measured by simple spirometry can be measured using techniques such as body plethysmography or gas dilution methods. Interpretation Reduced TLC indicates a restrictive ventilatory defect   3. Peak Expiratory Flow Rate (PEFR)  Procedure The patient takes a deep breath and blows forcefully into a peak flow meter  Interpretation A reduced or variable PEFR may indicate airflow limitation. It is particularly useful for monitoring asthma.

4. Diffusing Capacity of the Lung (DLCO) DLCO measures how efficiently gases pass from the alveoli into the blood. Procedure The patient inhales a small test gas mixture, holds the breath briefly and then exhales. The gas concentration is analyzed.  Interpretation * Reduced DLCO may occur in emphysema and interstitial lung disease. * It may also be reduced in some pulmonary vascular disorders.   5. Bronchodilator Reversibility Test  Procedure 1. Baseline spirometry is performed. 2. A bronchodilator is administered. 3. Spirometry is repeated after the appropriate waiting period. 4. The results are compared.  Interpretation A significant improvement in airflow after bronchodilator administration supports reversible airflow limitation, as commonly seen in asthma.   6. Six-Minute Walk Test  Procedure The patient walks along a measured corridor for six minutes at a comfortable pace.    Measurements * Distance walked * Heart rate * Breathlessness * Oxygen saturation    Interpretation Reduced walking distance or significant oxygen desaturation may indicate impaired exercise capacity.     7. Pulse Oximetry  Procedure   A pulse oximeter is placed on the finger or another suitable site.