20 types respiratory system disease treatment investigation finding differential diagnosis contraindication ICO management OPD prescription detail

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Based on the medical library findings and my comprehensive clinical knowledge, here is a detailed reference covering 20 Respiratory System Diseases with Treatment, Investigations, Findings, Differential Diagnosis, Contraindications, ICU Management, OPD Prescription, and more.

🫁 20 RESPIRATORY SYSTEM DISEASES — Complete Clinical Reference

1. BRONCHIAL ASTHMA

Definition: Chronic inflammatory airway disease with reversible bronchospasm, hyperresponsiveness, and airway remodeling.

Clinical Findings:

Wheezing, dyspnea, chest tightness, cough (worse at night/early morning)
Hyperresonance on percussion, prolonged expiration
Accessory muscle use in severe attacks
Pulsus paradoxus in severe asthma

Investigations:

Spirometry: FEV1/FVC < 0.70, ≥12% reversibility after bronchodilator
Peak Expiratory Flow Rate (PEFR) — diurnal variation >20%
Methacholine challenge test (bronchoprovocation)
ABG: hypoxia, hypocapnia (early); hypercapnia (severe/impending failure)
Allergy testing (IgE, skin prick test)
CXR: hyperinflation, flattened diaphragm

Differential Diagnosis:

COPD, vocal cord dysfunction, cardiac asthma (CHF), bronchiectasis, GERD, foreign body inhalation, tracheal stenosis

Treatment / OPD Prescription:

Step	Drug	Dose
Step 1 (Mild intermittent)	SABA (Salbutamol) inhaler	100–200 mcg PRN
Step 2	Low-dose ICS (Budesonide)	200–400 mcg/day
Step 3	ICS + LABA (Formoterol)	400 mcg + 12 mcg BD
Step 4	High-dose ICS + LABA + LTRA	Add Montelukast 10 mg OD
Add-on	Anti-IgE (Omalizumab)	SC q2–4 weeks

Prednisolone 40 mg OD × 5–7 days (acute exacerbation)
Ipratropium bromide MDI 40 mcg QID (add-on)
Leukotriene receptor antagonist: Montelukast 10 mg OD at night

Contraindications:

β-blockers (even selective) — worsen bronchospasm
NSAIDs/Aspirin in aspirin-exacerbated asthma
High-dose sedatives/opioids (suppress respiratory drive)

ICU Management (Status Asthmaticus):

Supplemental O₂ to maintain SpO₂ >94%
Continuous nebulized Salbutamol + Ipratropium
IV Magnesium sulfate 2 g over 20 min
IV Methylprednisolone 1–2 mg/kg/day
Heliox therapy
Intubation if: silent chest, altered consciousness, PaCO₂ rising, pH <7.2
Mechanical ventilation: permissive hypercapnia, low RR (12–14), long expiratory time

2. CHRONIC OBSTRUCTIVE PULMONARY DISEASE (COPD)

Definition: Progressive airflow obstruction (FEV1/FVC <0.70 post-bronchodilator) from emphysema and/or chronic bronchitis.

Clinical Findings:

Chronic productive cough, dyspnea, exercise intolerance
"Blue Bloater" (chronic bronchitis): cyanosis, edema, hypercapnia
"Pink Puffer" (emphysema): pursed-lip breathing, barrel chest, wasting
Decreased breath sounds, prolonged expiration, hyperresonance

Investigations:

Spirometry: FEV1/FVC <0.70 (GOLD criteria — Grade I–IV)
CXR: hyperinflation, bullae, flattened diaphragm, increased AP diameter
HRCT chest: centrilobular vs. panlobular emphysema
ABG: hypoxemia ± hypercapnia
CBC: polycythemia (secondary)
6-Minute Walk Test, Alpha-1 antitrypsin level

Differential Diagnosis:

Asthma, bronchiectasis, CHF, tuberculosis, obliterative bronchiolitis

OPD Prescription (GOLD ABCD):

Group	First Choice	Alternative
A (low risk, less symptoms)	SABA or SAMA PRN	LABA or LAMA
B (low risk, more symptoms)	LAMA or LABA	LAMA + LABA
C (high risk, less symptoms)	LAMA	LAMA + LABA or LABA + ICS
D (high risk, more symptoms)	LAMA + LABA	+ ICS if eos >300

Tiotropium (LAMA) 18 mcg OD inhaled
Salmeterol (LABA) 50 mcg BD inhaled
Roflumilast (PDE-4 inhibitor) 500 mcg OD — for frequent exacerbators
Influenza vaccine + Pneumococcal vaccine
Long-term O₂ therapy if PaO₂ <55 mmHg

Contraindications:

High-flow O₂ (>2–3 L/min) — risk of hypoxic drive abolition
Sedatives, opioids without caution
Indiscriminate β-blockers (use cardioselective cautiously)

ICU Management (Acute Exacerbation):

Controlled O₂: target SpO₂ 88–92%
Non-invasive ventilation (BiPAP) — first-line for hypercapnic respiratory failure
IV hydrocortisone 100 mg TDS or oral prednisolone
Nebulized salbutamol + ipratropium
Antibiotics (Amoxicillin-clavulanate, Azithromycin) if purulent sputum
Intubation if BiPAP fails

3. COMMUNITY-ACQUIRED PNEUMONIA (CAP)

Definition: Acute pulmonary infection in non-hospitalized patients or within 48 hours of admission.

Clinical Findings:

Fever, productive cough (rust-colored sputum in pneumococcal), pleuritic chest pain
Bronchial breathing, dullness on percussion, increased vocal fremitus
Crackles (crepitations), signs of consolidation

Investigations:

CXR: lobar consolidation, air bronchograms
CBC: leukocytosis (neutrophilia)
CRP, procalcitonin (elevated)
Sputum Gram stain & culture
Blood cultures (before antibiotics)
Urinary antigen: Legionella, Pneumococcus
ABG in severe disease
CURB-65 / PSI scoring

Differential Diagnosis:

Pulmonary TB, lung abscess, pulmonary edema, PE with infarction, ARDS, organizing pneumonia

OPD Prescription (Mild CAP — CURB-65 0–1):

Amoxicillin 500 mg TDS × 5–7 days (typical)
Azithromycin 500 mg OD × 5 days (atypical/allergy)
Doxycycline 100 mg BD × 5–7 days (alternative)
PCM (Paracetamol) 500–1000 mg TDS PRN
Adequate hydration

Contraindications:

Fluoroquinolones without ruling out TB (can mask TB)
Amoxicillin if penicillin allergy

ICU Management (Severe CAP — CURB-65 ≥3):

IV Ceftriaxone 1–2 g OD + Azithromycin 500 mg OD (or respiratory fluoroquinolone)
O₂ supplementation; NIV or intubation if needed
IV fluids, vasopressors if septic shock
Corticosteroids (Dexamethasone) if ARDS develops
Empyema drainage if present

4. PULMONARY TUBERCULOSIS (PTB)

Definition: Infection by Mycobacterium tuberculosis, primarily affecting lungs.

Clinical Findings:

Constitutional: fever (evening rise), night sweats, weight loss, anorexia
Hemoptysis, chronic productive cough >3 weeks
Upper lobe crackles, dullness; signs of cavitation

Investigations:

Sputum AFB (3 samples): smear microscopy
GeneXpert MTB/RIF (rapid PCR + rifampicin resistance)
Sputum culture (Lowenstein-Jensen medium — gold standard)
CXR: upper lobe infiltrates, cavities, fibrosis, Ghon complex
TST (Mantoux), IGRA (QuantiFERON-TB)
ADA (Adenosine deaminase) in pleural/CSF fluid
HIV testing (all TB patients)

Differential Diagnosis:

Lung carcinoma, pneumonia, lung abscess, histoplasmosis, sarcoidosis, COPD

OPD Prescription (DOTS — Category I: New Case):

Phase	Drugs	Duration
Intensive	HRZE (Isoniazid + Rifampicin + Pyrazinamide + Ethambutol)	2 months
Continuation	HR (Isoniazid + Rifampicin)	4 months

Pyridoxine (Vitamin B6) 25 mg OD (with Isoniazid — prevent neuropathy)
Rifampicin 600 mg, Isoniazid 300 mg, Pyrazinamide 1500 mg, Ethambutol 1200 mg (weight-based)

Contraindications:

Rifampicin in severe hepatic disease
Ethambutol in optic neuritis/poor vision
Pyrazinamide in hepatic failure, gout
Streptomycin in pregnancy (8th nerve damage)

ICU Management:

Respiratory isolation (negative pressure room)
IV nutrition, supportive care
Corticosteroids (Dexamethasone) for TB meningitis/pericarditis/pleural effusion
Hemoptysis: bronchial artery embolization

5. PULMONARY EMBOLISM (PE)

Definition: Obstruction of pulmonary arteries by thromboemboli, usually from DVT.

Clinical Findings:

Sudden dyspnea, pleuritic chest pain, hemoptysis (classic triad)
Tachycardia, tachypnea, hypoxia
Massive PE: hypotension, syncope, RV failure signs (raised JVP, S3)
Pleural rub, reduced breath sounds (infarction zone)

Investigations:

D-dimer (high sensitivity, low specificity — rule-out if low)
CT Pulmonary Angiography (CTPA) — gold standard
V/Q scan (if CTPA contraindicated)
ECG: sinus tachycardia; S1Q3T3 (classic but uncommon)
Echo: RV dilation, McConnell's sign, septal shift
Lower limb Doppler USS (DVT)
Troponin, BNP (risk stratification)
ABG: hypoxia, hypocapnia, increased A-a gradient

Differential Diagnosis:

Acute MI, aortic dissection, pneumothorax, pericarditis, pleuritis, anxiety attack

OPD Prescription (Low-Risk PE):

LMWH: Enoxaparin 1 mg/kg SC BD × 5 days, then
Rivaroxaban 15 mg BD × 21 days, then 20 mg OD × 3–6 months
OR Warfarin (INR target 2–3) — overlap with heparin × 5 days

Contraindications:

Thrombolytics in active bleeding, recent surgery/stroke, intracranial pathology
Warfarin in pregnancy (teratogenic — use LMWH instead)

ICU Management (Massive PE):

O₂, hemodynamic monitoring
IV unfractionated heparin (UFH) bolus 80 U/kg, then infusion
Systemic thrombolysis: Alteplase 100 mg over 2 hours (if no contraindication)
Catheter-directed thrombolysis/surgical embolectomy if thrombolysis fails
Vasopressors: Norepinephrine for RV failure
Avoid aggressive fluid resuscitation

6. PNEUMOTHORAX

Definition: Air in the pleural space — spontaneous (primary/secondary), traumatic, or tension.

Clinical Findings:

Sudden pleuritic chest pain, dyspnea
Absent/decreased breath sounds unilaterally
Hyperresonance on percussion
Tension PTX: tracheal deviation away, hypotension, JVD, absent breath sounds — medical emergency

Investigations:

CXR PA: absent lung markings, visible pleural line, mediastinal shift (tension)
CT chest: confirms small/complex pneumothorax
Lung USS: absent lung sliding, barcode sign

Differential Diagnosis:

Pleural effusion, bullous COPD, pulmonary infarction, rib fracture, acute MI

OPD/Ward Treatment:

Small (<2 cm) primary SPT: observation, O₂ 10 L/min (accelerates absorption)
Aspiration: 16–18G needle, 2nd ICS MCL
Intercostal drain (ICD) insertion for large/secondary/recurrent

Contraindications:

Bilateral simultaneous surgical pleurodesis contraindicated
Avoid positive pressure ventilation without ICD in tension PTX

ICU Management (Tension Pneumothorax):

Immediate needle decompression: 2nd ICS, MCL
Followed by ICD insertion (5th ICS, anterior axillary line)
Ventilation support as needed

7. PLEURAL EFFUSION

Definition: Excess fluid in pleural space — transudate or exudate (Light's criteria).

Clinical Findings:

Dyspnea, dull ache
Stony dull percussion, absent breath sounds
Decreased tactile fremitus, tracheal deviation (large effusion)
Pleural rub (early/resolving)

Investigations:

CXR: blunting costophrenic angle (>200 mL), homogenous opacity
USS guided thoracocentesis
Pleural fluid: protein, LDH, glucose, pH, cytology, culture, ADA
Light's Criteria (exudate if any): pleural protein/serum protein >0.5; pleural LDH/serum LDH >0.6; pleural LDH >2/3 upper normal serum
CT chest for underlying cause

Differential Diagnosis:

Transudate: CHF, cirrhosis, nephrotic syndrome, hypoalbuminemia
Exudate: TB, malignancy, pneumonia (parapneumonic), PE, connective tissue disease

OPD Prescription:

Treat underlying cause
Therapeutic thoracocentesis if symptomatic (drain <1500 mL at a time)
Furosemide 40 mg OD (if cardiac/renal)
Anti-TB drugs if TB effusion

Contraindications:

Rapid large drainage (>1500 mL) — risk of re-expansion pulmonary edema
Anticoagulants in hemothorax without drainage

ICU Management:

Large ICD for empyema/hemothorax
tPA (Alteplase) intrapleural for loculated empyema
Decortication if organized empyema

8. BRONCHIECTASIS

Definition: Permanent, abnormal dilatation of bronchi from repeated infection/inflammation.

Clinical Findings:

Chronic productive cough — "cupfuls" of purulent sputum (worse in morning)
Hemoptysis, halitosis
Clubbing of fingers (chronic)
Coarse crackles, rhonchi; lower zones affected most (postinfective)

Investigations:

HRCT chest (gold standard): "signet ring sign," "tram-track sign," mucus plugging
Sputum culture (Pseudomonas, Staph, H. influenzae common)
Spirometry: mixed obstructive-restrictive
Bronchoscopy (if localized disease or bleeding)
Sweat chloride test (if CF suspected)
Immunoglobulin levels, ABPA testing

Differential Diagnosis:

COPD, TB, lung abscess, asthma

OPD Prescription:

Chest physiotherapy + postural drainage (twice daily)
Nebulized hypertonic saline (3–7%) to aid expectoration
Amoxicillin-clavulanate 625 mg TDS × 14 days (acute exacerbation)
Ciprofloxacin 500–750 mg BD (Pseudomonas)
Azithromycin 250 mg 3×/week (prophylaxis, anti-inflammatory)
Bronchodilators if reversible component

Contraindications:

Mucolytics with active hemoptysis
Routine long-term antibiotics without culture guidance

ICU Management:

Massive hemoptysis: bronchial artery embolization
Lung resection for localized refractory disease

9. LUNG ABSCESS

Definition: Localized suppuration with parenchymal necrosis forming a cavity.

Clinical Findings:

Fever (hectic/remittent), rigors, foul-smelling/copious sputum
Pleuritic pain, hemoptysis, weight loss, clubbing
Dullness over cavity, amphoric breath sounds, post-tussive crackles

Investigations:

CXR: thick-walled cavity with air-fluid level
CT chest: confirms cavity, relationship to pleura
Sputum culture, blood culture, bronchoscopy (to rule out malignancy/foreign body)
CBC: leukocytosis
LFTs (anaerobic infections from aspiration)

Differential Diagnosis:

Cavitating TB, cavitating carcinoma, empyema with bronchopleural fistula, echinococcal cyst, Wegener's granulomatosis

OPD Prescription:

Amoxicillin-clavulanate 1 g BD × 4–6 weeks
OR Clindamycin 300 mg TDS (anaerobes) + Ceftriaxone IV in severe cases
Metronidazole 400 mg TDS for anaerobic coverage
Postural drainage

Contraindications:

Early surgical resection (allow antibiotic trial first)
Blind bronchoscopy in unstable patient

ICU Management:

IV antibiotics (Piperacillin-tazobactam + Metronidazole)
CT-guided percutaneous drainage if not responding
Surgical drainage/lobectomy for refractory cases

10. PULMONARY FIBROSIS (IPF — Idiopathic Pulmonary Fibrosis)

Definition: Progressive fibrosing interstitial pneumonia of unknown cause.

Clinical Findings:

Progressive exertional dyspnea, dry cough
"Velcro crackles" at lung bases
Finger clubbing (50%)
Cyanosis (late), signs of pulmonary hypertension (RHF)

Investigations:

HRCT: "honeycombing," traction bronchiectasis, basal/subpleural distribution — UIP pattern
Spirometry: restrictive pattern (↓FVC, ↓TLC, ↓DLCO)
ABG: hypoxia, ↓PaO₂
Surgical lung biopsy (if HRCT inconclusive)
ANA, RF, anti-CCP (exclude connective tissue disease)
6MWT (desaturation)

Differential Diagnosis:

Hypersensitivity pneumonitis, NSIP (connective tissue disease), sarcoidosis, asbestosis, DIP

OPD Prescription:

Nintedanib 150 mg BD (tyrosine kinase inhibitor — slows progression)
Pirfenidone 801 mg TDS (anti-fibrotic)
O₂ therapy (long-term, ambulatory)
Pulmonary rehab
Lung transplant referral (definitive)

Contraindications:

Corticosteroids are NOT recommended in IPF (no benefit, potential harm)
NSAIDs for pain (monitor renal function)

ICU Management (Acute Exacerbation IPF):

High-flow O₂ / NIV
Pulse methylprednisolone 500–1000 mg IV × 3 days
Broad-spectrum antibiotics (to cover superinfection)
Lung transplant evaluation
Mechanical ventilation — generally avoided (poor outcomes)

11. SARCOIDOSIS

Definition: Multisystem granulomatous disease of unknown cause; lungs involved in >90%.

Clinical Findings:

Dry cough, dyspnea, bilateral hilar lymphadenopathy
Erythema nodosum, uveitis, parotid swelling (Heerfordt syndrome)
Löfgren's syndrome: fever + EN + BHL + arthritis
Lupus pernio, cranial nerve palsy, heart block

Investigations:

CXR: Stage 0–IV (BHL, pulmonary infiltrates, fibrosis)
HRCT: perilymphatic nodules, beading along bronchovascular bundles
Bronchoscopy + BAL + TBLB (non-caseating granulomas)
ACE level (elevated in 60%)
Serum calcium, 24h urine calcium (elevated)
PFTs: restrictive pattern
PET scan for systemic involvement

Differential Diagnosis:

TB (differentiate: granulomas are non-caseating in sarcoidosis), lymphoma, berylliosis, hypersensitivity pneumonitis

OPD Prescription:

Mild (BHL only): observation (many spontaneously remit)
Prednisolone 20–40 mg OD → taper over 6–12 months (symptomatic/progressive disease)
Methotrexate or Azathioprine (steroid-sparing agents)
Hydroxychloroquine (skin/hypercalcemia)

Contraindications:

Calcium supplements/Vitamin D (worsen hypercalcemia)
Unguided high-dose steroids without confirmed diagnosis

ICU Management:

Cardiac sarcoidosis: pacemaker/ICD for heart block/VT
Acute respiratory failure: IV methylprednisolone

12. ACUTE RESPIRATORY DISTRESS SYNDROME (ARDS)

Definition: Acute diffuse inflammatory lung injury causing non-cardiogenic pulmonary edema (Berlin Definition: PaO₂/FiO₂ <300).

Clinical Findings:

Acute severe dyspnea within 1 week of inciting event
Bilateral crackles, refractory hypoxemia
Tachycardia, cyanosis, use of accessory muscles
Signs of precipitant (sepsis, trauma, aspiration, pancreatitis)

Investigations:

CXR/CT: bilateral diffuse infiltrates not explained by effusion/cardiac failure
ABG: severe hypoxemia, PaO₂/FiO₂ <300
PCWP <18 mmHg (or no clinical evidence of CHF)
CBC, CRP, blood cultures, lactate
Echocardiogram (exclude cardiogenic pulmonary edema)
Berlin Criteria: Mild (200–300), Moderate (100–200), Severe (<100)

Differential Diagnosis:

Cardiogenic pulmonary edema, diffuse alveolar hemorrhage, acute interstitial pneumonia, pneumonia

OPD Prescription: Not applicable — ARDS requires ICU care.

ICU Management (Lung Protective Ventilation — ARDSnet):

Low tidal volume: 6 mL/kg ideal body weight
PEEP titration (FiO₂-PEEP table)
Plateau pressure <30 cmH₂O
Prone positioning (>12–16 h/day) — reduces mortality
Neuromuscular blockade (Cisatracurium) if P/F <150
Conservative fluid strategy
Dexamethasone 6 mg IV OD × 10 days
Treat underlying cause (sepsis protocol)

13. SLEEP APNEA (OBSTRUCTIVE SLEEP APNEA — OSA)

Definition: Repetitive upper airway collapse during sleep causing apnea/hypopnea.

Clinical Findings:

Loud snoring, observed apneas, excessive daytime sleepiness
Morning headaches, nocturnal choking/gasping
Obesity (neck circumference >40 cm), retrognathia, enlarged tonsils
Epworth Sleepiness Scale >10

Investigations:

Overnight polysomnography (gold standard): AHI >5/hr (mild), >15 (moderate), >30 (severe)
Home sleep apnea testing (portable monitoring)
Pulse oximetry (overnight desaturations)
ABG (if overlap syndrome/OHS suspected)
ECG, ECHO (cardiovascular complications)

Differential Diagnosis:

Central sleep apnea, obesity hypoventilation syndrome (OHS), narcolepsy, restless leg syndrome

OPD Prescription:

CPAP (Continuous Positive Airway Pressure) — first-line therapy
Mandibular advancement device (mild-moderate)
Weight reduction (BMI >30)
Positional therapy (avoid supine sleeping)
Avoid alcohol/sedatives at night
Surgery: UPPP (uvulopalatopharyngoplasty), bariatric surgery

Contraindications:

Sedatives/hypnotics (benzodiazepines, opioids) — worsen apnea
CPAP in untreated pneumothorax/hypotension

ICU Management (OHS/Respiratory Failure):

NIV (BiPAP), then CPAP
Treatment of precipitating infections, diuresis for fluid overload

14. PULMONARY HYPERTENSION (PH)

Definition: Mean pulmonary artery pressure >20 mmHg at rest on right heart catheterization.

Clinical Findings:

Progressive dyspnea, fatigue, syncope on exertion
Loud P2, right ventricular heave, TR murmur
Raised JVP, peripheral edema (Cor Pulmonale — late)

Investigations:

ECG: RV hypertrophy, right axis deviation, P-pulmonale
Echo (doppler): ↑RVSP, RV dilation/hypertrophy — screening tool
Right Heart Catheterization (gold standard): mPAP >20 mmHg, PCWP ≤15 (pre-capillary)
CT chest: enlarged pulmonary arteries, mosaic attenuation (CTEPH)
V/Q scan (CTEPH), 6MWT, PFTs, ABG
BNP/NT-proBNP (severity/prognosis)

Differential Diagnosis:

LV heart failure (Group 2 PH), COPD/ILD-related PH (Group 3), CTEPH (Group 4)

OPD Prescription (Group 1 — PAH):

Endothelin receptor antagonists: Ambrisentan 5–10 mg OD or Bosentan 125 mg BD
PDE-5 inhibitors: Sildenafil 20 mg TDS or Tadalafil 40 mg OD
Prostacyclin analogues: Iloprost inhaled, Epoprostenol IV (severe)
Diuretics: Furosemide 40 mg OD (fluid overload)
Warfarin (IPAH — anticoagulation; INR 1.5–2.5)
Calcium channel blockers (if vasoreactive)
O₂ (if hypoxic)

Contraindications:

Bosentan in pregnancy (teratogenic) — Category X
PDE-5 inhibitors with nitrates (severe hypotension)
Vasodilators in fixed pulmonary hypertension or PVOD

ICU Management:

Vasopressors: Norepinephrine + Vasopressin (RV failure)
Inhaled NO, prostacyclins
ECMO as bridge to transplant

15. LUNG CANCER (BRONCHOGENIC CARCINOMA)

Definition: Malignant neoplasm arising from bronchial epithelium — most common: adenocarcinoma > squamous cell > small cell > large cell.

Clinical Findings:

Cough, hemoptysis, weight loss, dyspnea
Hoarseness (recurrent laryngeal nerve), dysphagia
SVC obstruction syndrome (SCLC)
Pancoast tumor: Horner's syndrome + arm pain (C8–T2)
Paraneoplastic: SIADH, Cushing's (SCLC), hypercalcemia, hypertrophic osteoarthropathy (squamous cell)

Investigations:

CXR: mass, hilar enlargement, atelectasis, effusion
CT chest/abdomen/pelvis (staging)
PET-CT (mediastinal staging, metastasis)
Bronchoscopy + BAL + biopsy
CT-guided percutaneous biopsy
Sputum cytology
Molecular markers: EGFR, ALK, ROS1, KRAS, PD-L1 (NSCLC)
Brain MRI (SCLC — staging)

Differential Diagnosis:

Pulmonary metastasis, TB, lung abscess, carcinoid tumor, lymphoma, mesothelioma

OPD Prescription:

NSCLC early stage: Surgery (lobectomy) + adjuvant chemotherapy
NSCLC metastatic EGFR+: Erlotinib/Gefitinib/Osimertinib
ALK+: Crizotinib/Alectinib
Immunotherapy: Pembrolizumab (PD-L1 >50%)
SCLC limited: Cisplatin/Etoposide + concurrent radiotherapy
SCLC extensive: Atezolizumab + Carboplatin/Etoposide
Palliative: O₂, opioids for dyspnea, bisphosphonates (bone mets)

Contraindications:

Surgery in FEV1 <40% predicted
Platinum chemotherapy in GFR <30 mL/min (Carboplatin preferred)
Immunotherapy in active autoimmune disease

ICU Management:

SVC syndrome: dexamethasone, anticoagulation, stent
Massive hemoptysis: bronchial artery embolization
Respiratory failure: NIV/intubation

16. MESOTHELIOMA

Definition: Malignant tumor of the pleural mesothelium — strongly associated with asbestos exposure.

Clinical Findings:

Progressive dyspnea, non-pleuritic chest pain
Persistent pleural effusion (hemorrhagic)
Chest wall invasion (late), weight loss

Investigations:

CXR: unilateral pleural effusion, pleural thickening
CT chest: circumferential pleural thickening, encasement, rib erosion
PET-CT
Thoracoscopy + biopsy (gold standard): epithelioid, sarcomatoid, biphasic
Immunohistochemistry: Calretinin+, WT1+, CEA−
Mesothelin levels (serum)

Differential Diagnosis:

Metastatic adenocarcinoma to pleura, fibrous pleurisy, primary lung cancer

Treatment/OPD:

Cisplatin + Pemetrexed (+ Bevacizumab) — standard chemotherapy
Nivolumab + Ipilimumab (immunotherapy — first-line in unresectable)
Surgery (EPP — extrapleural pneumonectomy) in selected patients
Radiotherapy (prophylactic to procedure sites)

Contraindications:

EPP in bilateral disease or poor lung function

17. HYPERSENSITIVITY PNEUMONITIS (HP)

Definition: Immune-mediated interstitial lung disease from repeated inhalation of organic antigens.

Clinical Findings:

Acute: 4–8 hours after exposure — fever, cough, myalgia, dyspnea, crackles
Chronic: progressive dyspnea, dry cough, weight loss, clubbing
Exposure history: farmer's lung (thermophilic Actinomyces), bird fancier's lung

Investigations:

HRCT: ground-glass opacity, centrilobular nodules, air trapping (mosaic); fibrosis in chronic
Precipitating antibodies (serum IgG against offending antigen)
BAL: lymphocytosis (CD8+ predominant)
PFTs: restrictive pattern, ↓DLCO
Lung biopsy if unclear

Differential Diagnosis:

Sarcoidosis, IPF, NSIP, atypical pneumonia, ARDS

OPD Prescription:

Antigen avoidance (most important)
Prednisolone 40–60 mg/day × 2–4 weeks, then taper
Mycophenolate/Azathioprine (fibrotic HP)
Lung transplant (progressive fibrotic HP)

Contraindications:

Return to antigen exposure environment
High-dose steroids without diagnosis confirmation

18. PNEUMOCONIOSIS (OCCUPATIONAL LUNG DISEASE)

Definition: Dust-induced lung fibrosis — Silicosis (silica), Coal worker's pneumoconiosis, Asbestosis.

Clinical Findings:

Progressive dyspnea (years after exposure), dry cough
Crackles (asbestosis), eggshell calcification in hilar nodes (silicosis)
Rheumatoid arthritis association (Caplan syndrome — coal dust + RA)
Risk of TB (silicosis)

Investigations:

CXR: upper lobe nodules (silicosis/CWP), bilateral basal fibrosis (asbestosis), pleural plaques (asbestosis)
HRCT: definitive
PFTs: restrictive ± obstructive
Occupational history (latency 10–40 years)

OPD Treatment:

No specific treatment — remove from exposure
Treat complications: TB treatment, COPD management
Pulmonary rehab
Workers' compensation
Lung transplant for end-stage

Contraindications:

Return to dusty environment
Corticosteroids — no proven benefit in silicosis

19. COR PULMONALE (RIGHT HEART FAILURE DUE TO LUNG DISEASE)

Definition: Right ventricular hypertrophy/failure due to pulmonary hypertension secondary to lung disease.

Clinical Findings:

Ankle edema, raised JVP, tender hepatomegaly
Parasternal heave, loud P2
Cyanosis, dyspnea — features of underlying COPD/ILD

Investigations:

ECG: P-pulmonale, RVH, right axis deviation
Echo: RV hypertrophy, ↑RVSP
CXR: enlarged pulmonary artery, cardiomegaly (right-sided)
BNP (elevated), ABG (hypoxia ± hypercapnia)
Right heart catheterization (gold standard)

OPD Prescription:

Treat underlying lung disease (COPD management)
Long-term O₂ therapy (LTOT) >15 h/day if PaO₂ <55 mmHg
Diuretics: Furosemide 40–80 mg OD
Digoxin (AF with fast ventricular rate)
Salt restriction, fluid restriction

Contraindications:

Aggressive diuresis (reduces preload → ↓CO)
Vasodilators without careful monitoring (may worsen systemic hypotension)
Warfarin without clear indication

20. ALLERGIC BRONCHOPULMONARY ASPERGILLOSIS (ABPA)

Definition: Hypersensitivity reaction to Aspergillus fumigatus in sensitized asthma/CF patients.

Clinical Findings:

Worsening asthma, expectoration of brownish mucus plugs
Low-grade fever, peripheral eosinophilia
Fleeting pulmonary infiltrates on CXR
Proximal bronchiectasis (central)

Investigations:

Total IgE >1000 IU/mL (markedly elevated)
Specific IgE/IgG to A. fumigatus (positive)
Skin prick test to Aspergillus (positive — immediate)
Eosinophilia >0.5×10⁹/L
CXR/HRCT: central bronchiectasis, mucus plugging, "finger-in-glove" sign
Sputum: Aspergillus hyphae, eosinophils

Differential Diagnosis:

Asthma alone, eosinophilic pneumonia, HP, Churg-Strauss (EGPA)

OPD Prescription:

Oral prednisolone 0.5 mg/kg/day × 2 weeks, then taper over 6–12 months
Itraconazole 200 mg BD × 16 weeks (steroid-sparing; monitor LFTs)
Voriconazole (alternative antifungal)
ICS + LABA for underlying asthma
Omalizumab (anti-IgE) in refractory cases

Contraindications:

Itraconazole with drugs metabolized by CYP3A4 (terfenadine, cisapride — QT prolongation)
Systemic antifungals in hepatic impairment without monitoring

QUICK REFERENCE SUMMARY TABLE

#	Disease	Key Investigation	First-Line Treatment	Critical Contraindication	ICU Priority
1	Asthma	Spirometry (reversibility)	ICS + SABA	β-blockers	IV MgSO₄, BiPAP
2	COPD	Spirometry FEV1/FVC <0.7	LAMA + LABA	High-flow O₂	BiPAP, controlled O₂
3	CAP	CXR + sputum culture	Amoxicillin/Azithromycin	Fluoroquinolones before TB exclusion	IV Ceftriaxone + Azithromycin
4	PTB	GeneXpert + AFB smear	HRZE × 2m + HR × 4m	Rifampicin in liver failure	Isolation + IV nutrition
5	Pulmonary Embolism	CTPA	Anticoagulation	Thrombolytics in active bleed	Alteplase, UFH
6	Pneumothorax	CXR/USS	Aspiration/ICD	PPV without ICD in tension	Needle decompression
7	Pleural Effusion	Thoracocentesis	Treat cause + drain	Rapid drainage >1500 mL	ICD, tPA (empyema)
8	Bronchiectasis	HRCT chest	Chest physio + antibiotics	Mucolytics in hemoptysis	BAE (massive hemoptysis)
9	Lung Abscess	CT chest	Amox-Clav + Clindamycin	Early surgery	Perc. drainage
10	IPF	HRCT (honeycombing)	Nintedanib/Pirfenidone	Corticosteroids	Avoid MV if possible
11	Sarcoidosis	ACE + HRCT + biopsy	Prednisolone	Ca/Vit D supplements	IV steroids, pacemaker
12	ARDS	PaO₂/FiO₂ <300	Lung-protective ventilation	High tidal volume	Prone positioning
13	OSA	Polysomnography	CPAP	Sedatives/benzos	BiPAP (OHS)
14	Pulmonary HT	RHC (mPAP >20)	Ambrisentan + Sildenafil	Bosentan in pregnancy	Inhaled NO, vasopressors
15	Lung Cancer	CT + Biopsy + Molecular	Surgery/Targeted/Immuno	Surgery if FEV1 <40%	BAE, dexamethasone
16	Mesothelioma	Thoracoscopy biopsy	Cisplatin + Pemetrexed	EPP in bilateral disease	Palliative
17	HP	HRCT + precipitins	Antigen avoidance + steroids	Re-exposure to antigen	IV steroids
18	Pneumoconiosis	HRCT + occupational Hx	Exposure removal	Return to dusty work	TB treatment if co-infected
19	Cor Pulmonale	Echo + ECG + RHC	LTOT + diuretics	Aggressive diuresis	O₂ + vasopressors
20	ABPA	Total IgE + specific IgE	Prednisolone + Itraconazole	Itraconazole + CYP3A4 drugs	Systemic antifungals

KEY ABBREVIATIONS

ICS = Inhaled Corticosteroid | LABA = Long-Acting Beta-2 Agonist | LAMA = Long-Acting Muscarinic Antagonist | SABA = Short-Acting Beta-2 Agonist
BiPAP = Bilevel Positive Airway Pressure | CPAP = Continuous PAP | NIV = Non-Invasive Ventilation
HRCT = High-Resolution CT | BAE = Bronchial Artery Embolization | AFB = Acid-Fast Bacilli
ICD = Intercostal Drain | UFH = Unfractionated Heparin | LMWH = Low Molecular Weight Heparin
DLCO = Diffusion Capacity for CO | FVC = Forced Vital Capacity | TLC = Total Lung Capacity

Sources: Murray & Nadel's Textbook of Respiratory Medicine; Fishman's Pulmonary Diseases and Disorders; Harrison's Principles of Internal Medicine 22E; Goldman-Cecil Medicine; Tintinalli's Emergency Medicine

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