Asthma mbbs final year medicine exam with answer sheet presentation tips

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asthma MBBS final year medicine exam important questions answer writing tips 2024

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Asthma - MBBS Final Year Medicine Exam Guide

Compiled from Goldman-Cecil Medicine, Murray & Nadel's Respiratory Medicine, and Fishman's Pulmonary Diseases

EXAM PRESENTATION TIPS (Read First!)

How to write a high-scoring answer in finals:

Start with definition - always the first sentence of any long-answer
Use headings - Definition / Epidemiology / Pathophysiology / Clinical Features / Diagnosis / Classification / Management / Complications / Status Asthmaticus
Draw diagrams - spirometry flow-volume loop (obstructive pattern), stepwise GINA ladder
Use tables - severity classification, GINA control criteria, drug table
Bold key terms - FEV1, FVC, IgE, GINA, ICS, SABA, LABA
Finish with prognosis/complications - examiners love this
Status asthmaticus = separate 5-mark section - know it cold
For a 10-mark question: ~2.5 pages; for 5-mark: ~1.5 pages; for short notes: 1 page

1. DEFINITION

Asthma is a clinical syndrome of unknown etiology characterized by recurrent episodes of airway obstruction that resolve spontaneously or with treatment. It occurs due to chronic airway inflammation with reversible airflow obstruction and airway hyperresponsiveness - though some obstruction may become irreversible over time.

(Goldman-Cecil Medicine, Chapter 75)

2. EPIDEMIOLOGY (2-3 lines for exams)

~340 million people worldwide affected; ~420,000 deaths/year
~8% of US adults; prevalence rising globally
Before puberty: boys > girls; after puberty: women > men (ratio 1.8:1)
Onset usually before age 25, but can occur at any age
Prevalence plateaued after 2015

3. PATHOPHYSIOLOGY (Most asked - 5 marks)

a) Genetics

~60% heritability (twin studies)
Multiple genetic loci - mainly immune-related genes

b) Pathology - Key Triad

Component	What Happens
Airway inflammation	Eosinophilic (type-2 high) infiltration, mast cell activation, T-lymphocytes
Bronchospasm	Smooth muscle contraction, airway hyperresponsiveness
Airway remodeling	Subepithelial fibrosis, goblet cell hyperplasia, mucus hypersecretion

c) Endotypes / Types

Atopic (allergic) asthma - most common; IgE-mediated response to environmental allergens (dust mites, pollen, pet dander); Type 1 hypersensitivity; eosinophilic pattern
Non-atopic asthma - triggered by infections, exercise, cold air, NSAIDs; not IgE-mediated
Exercise-induced asthma - 8-15 min post-exercise bronchospasm
Occupational asthma - workplace sensitizers (isocyanates, flour, latex)
Aspirin-sensitive asthma (Samter's triad: asthma + nasal polyps + aspirin sensitivity)

d) Mediators

Mast cells release: histamine, leukotrienes (LTC4, LTD4), prostaglandins
Eosinophils release: major basic protein, eosinophil cationic protein - cause epithelial damage
Cytokines IL-4, IL-5, IL-13 drive the type-2 inflammatory response

4. CLINICAL FEATURES

Classic Triad (must mention):

Episodic breathlessness + Wheeze + Dry cough (worse at night / early morning)

Additional features:

Chest tightness
Triggered by allergens, exercise, cold air, smoke, infections
Nocturnal symptoms - due to low cortisol levels + increased vagal tone at night
Diurnal variation - symptoms worse in early morning (circadian pattern of airway narrowing)

On Examination:

Bilateral expiratory wheeze
Prolonged expiration
Hyperinflated chest (barrel chest in chronic/severe)
Tachycardia, tachypnea in acute episode
Silent chest = life-threatening sign (no air movement)

5. DIAGNOSIS

A. Spirometry (Most important - draw a diagram!)

Parameter	Normal	Asthma (obstructive)
FEV1	Normal	Reduced
FVC	Normal	Normal or mildly reduced
FEV1/FVC ratio	>0.75	<0.70 (obstructive)
Post-bronchodilator FEV1	-	≥12% and ≥200 mL increase = reversibility

Reversibility = hallmark of asthma (distinguishes from COPD)
PEFR (Peak Expiratory Flow Rate) - reduced in acute attack; used for home monitoring
Diurnal variation in PEFR >20% is diagnostic

B. Bronchial Provocation Test

Methacholine / Histamine challenge - confirms airway hyperresponsiveness
PC20 (provocative concentration causing 20% fall in FEV1) - positive at <8 mg/mL

C. Arterial Blood Gases (ABG) - exam favorite!

Stage	pH	PaO2	PaCO2
Mild attack	↑ (alkalosis)	↓ slightly	↓ (hyperventilation)
Severe attack	Normal/↓	↓↓ (<60 mmHg)	Normal or ↑ = DANGER

Key exam point: Normal or rising PaCO2 in severe asthma = impending respiratory failure - requires immediate ICU

D. Other Investigations

Blood eosinophilia - common in type-2 high (atopic) asthma
Elevated serum IgE - indicates atopic asthma; guides anti-IgE therapy
Skin prick test / RAST - identifies specific allergens
CXR: Often normal; severe = hyperinflation; complications = pneumothorax, pneumomediastinum, subcutaneous emphysema
FeNO (Fractional exhaled nitric oxide) - elevated in eosinophilic airway inflammation

6. CLASSIFICATION OF SEVERITY (GINA / NAEPP)

(Draw this as a table - earns marks)

Category	Daytime Symptoms	Night Symptoms	PEFR/FEV1	Variability
Intermittent	≤2/week	≤2/month	≥80% predicted	<20%
Mild persistent	>2/week but not daily	>2/month	≥80%	20-30%
Moderate persistent	Daily	>1/week	60-80%	>30%
Severe persistent	Continuous	Frequent	<60%	>30%

7. MANAGEMENT (GINA Stepwise Approach)

(Draw the stepwise ladder - 5 steps)

Controller vs. Reliever Drugs

Type	Drugs	Mechanism
Reliever (SABA)	Salbutamol, Terbutaline	β2-agonist → bronchodilation (quick relief)
Controller (ICS)	Beclomethasone, Budesonide, Fluticasone	Anti-inflammatory; mainstay of long-term control
LABA	Salmeterol, Formoterol	Long-acting β2-agonist; always combined with ICS
Leukotriene modifier	Montelukast, Zafirlukast	Block LTD4 receptors; useful in aspirin-sensitive asthma
Theophylline	Aminophylline	PDE inhibitor; now rarely used
Anti-IgE	Omalizumab	Biologic; for severe allergic asthma with high IgE
Anti-IL-5	Mepolizumab, Benralizumab	Biologic; for severe eosinophilic asthma
Oral corticosteroids	Prednisolone	Short bursts for exacerbations or Step 5

GINA 5-Step Ladder (write this in exams)

Step 1: As-needed low-dose ICS-formoterol OR SABA (for mild intermittent)
Step 2: Low-dose ICS daily + as-needed SABA
Step 3: Low-dose ICS-LABA OR medium-dose ICS
Step 4: Medium/high-dose ICS-LABA ± LAMA (tiotropium)
Step 5: High-dose ICS-LABA + biologic (Omalizumab/Mepolizumab) ± OCS

Key point: ICS is the cornerstone of asthma management at all steps from Step 2 onwards.

Non-pharmacological:

Avoid triggers (allergens, smoke, NSAIDs in aspirin-sensitive)
Annual influenza vaccination
Pneumococcal vaccination (Pneumovax for adults 19-64 with chronic illness)
Written Asthma Action Plan
Inhaler technique education

8. STATUS ASTHMATICUS (5-mark must-know)

Definition: Severe asthma attack unresponsive to conventional bronchodilators lasting >24 hours (or any life-threatening acute severe asthma).

Life-threatening features (REMEMBER: "Silent CHAOS"):

Silent chest (no wheeze = no air entry)
Confusion / altered consciousness
Hypercapnia (rising PaCO2)
Arrhythmia / bradycardia
Oxygen saturation <92%
Slow respiratory rate / exhaustion

Management of Acute Severe Asthma:

Immediate (ABC):

Oxygen - high flow, maintain SpO2 94-98%
Nebulized SABA - Salbutamol 2.5-5 mg every 20 min (or back-to-back)
Ipratropium bromide (anticholinergic) nebulized - add to SABA
IV/oral systemic corticosteroids - Hydrocortisone 100-200 mg IV OR Prednisolone 40-50 mg oral
IV Magnesium sulfate 1.2-2 g IV over 20 min - causes bronchial smooth muscle relaxation (for severe cases not responding)
IV Aminophylline - add in life-threatening (with monitoring for toxicity)
Intubation + mechanical ventilation - last resort for respiratory failure

Monitoring: Serial PEFR, ABG, SpO2, urine output

9. COMPLICATIONS

Pneumothorax / Pneumomediastinum / Subcutaneous emphysema
Status asthmaticus
Respiratory failure
Airway remodeling (irreversible obstruction)
Growth retardation in children (severe, uncontrolled)
Cor pulmonale (chronic severe asthma - rare)
Drug side-effects: oral thrush (ICS), hypothalamic-pituitary suppression (high-dose ICS), tachycardia (SABA)

10. DIFFERENTIAL DIAGNOSIS (2-liner in exams)

COPD (irreversible obstruction, smoker, older age)
Cardiac asthma (left heart failure - "cardiac wheeze")
Foreign body / endobronchial tumor
Vocal cord dysfunction
Pulmonary embolism

LIKELY EXAM QUESTIONS WITH MARKS

Question	Suggested Marks
Define asthma. Classify and discuss its management.	10 marks
Write short notes on status asthmaticus.	5 marks
Pathophysiology of bronchial asthma.	5 marks
Stepwise management of asthma (GINA guidelines).	5 marks
Diagnosis of asthma including spirometry findings.	5 marks
Drugs used in asthma with mechanism of action.	5 marks
Asthma vs COPD (differentiation).	5 marks

QUICK RECALL MNEMONICS

ASTHMA triggers = Alergens, Smoke, Temperature (cold), Humidity, Medications (NSAIDs, β-blockers), Anxiety/exercise
Life-threatening signs = CHASM: Cyanosis, Hypercapnia, Arrhythmia, Silent chest, Mental confusion
Samter's Triad = Asthma + Nasal polyps + Aspirin sensitivity
ICS side effects = Oral candidiasis + Dysphonia (always rinse mouth after use)

KEY HIGH-YIELD POINTS FOR FINALS

FEV1/FVC <0.70 + >12% reversibility = diagnostic of asthma
Normal PaCO2 in severe attack = impending respiratory failure (danger sign)
ICS is the cornerstone of long-term management
Omalizumab = anti-IgE biologic for severe allergic asthma
Magnesium sulfate IV = important in acute severe asthma not responding to standard therapy
Silent chest = life-threatening, not a reassuring sign
SABA alone for mild intermittent asthma; add ICS from Step 2 onwards
FeNO elevated in eosinophilic asthma - predicts steroid response

Sources: Goldman-Cecil Medicine (Chapter 75 - Asthma, Drazen & Bel); Fishman's Pulmonary Diseases (Chapter on Management of Chronic Asthma); Murray & Nadel's Textbook of Respiratory Medicine (Impairment Rating and Acute Management)

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