GC041 Cough In A Chronic Smoker: COPD; Smoking Cessation
Chronic obstructive pulmonary disease (COPD) is a progressive, largely irreversible airflow limitation caused by chronic inflammatory response to inhaled irritants—predominantly tobacco smoke—necessitating smoking cessation as the single most effective intervention to slow disease progression.
COPD & Smoking Cessation — GC 041
Lecture Map
This lecture covers two tightly linked topics: Chronic Obstructive Pulmonary Disease (COPD) and Smoking Cessation. COPD is one of the most common medical conditions you'll encounter on the wards — it's a disease primarily caused by smoking, and the single most effective intervention to alter its natural history is stopping smoking. The lecture walks through the full arc: what COPD is, why it happens, how to recognise it, how to investigate and manage it (both stable and acute), and then pivots to the pharmacology and psychology of quitting smoking. Understanding COPD from first principles — the protease-antiprotease imbalance, the distinction between small airway disease and parenchymal destruction, why controlled oxygen matters, why cor pulmonale develops — is what separates a student who understands the disease from one who merely memorises drug lists.
"You will learn:
- the risk factors & pathophysiology of COPD
- the clinical features and complications of COPD
- the investigations & principles of management of COPD
- the psychology of smoking, the methods of and difficulties encountered in smoking cessation
- a clinical case study"
COPD and smoking cessation appear repeatedly in past HKU Fourth Summative papers — as MCQs (LTOT criteria, best smoking cessation agent), SAQs (comorbidities of COPD, spirometry interpretation), and minicases (chronic smoker with cough → differential diagnosis → investigations → complications). The 2024 SAQ directly asked for 5 cardiorespiratory and 5 non-cardiorespiratory comorbidities of COPD [7]. The 2022 MCQ tested best smoking cessation option (answer: varenicline) [6] and LTOT duration [6]. This is extremely high-yield territory.
"COPD, a common preventable and treatable disease, is characterized by persistent respiratory symptoms and airflow limitation that are due to airway &/or alveolar abnormalities usually caused by significant exposure to noxious particles or gases. Exacerbations and comorbidities contribute to the overall severity in individual patients." — GOLD definition, per lecture [1]
Let's unpack this definition because examiners love asking you to define COPD:
| Key phrase | Why it matters |
|---|---|
| "Common, preventable, treatable" | COPD is not curable, but it IS preventable (don't smoke) and treatable (bronchodilators, O₂, rehab). This framing is deliberate. |
| "Persistent respiratory symptoms" | Not episodic like asthma. Symptoms are there every day. |
| "Airflow limitation" | This is the spirometric hallmark — FEV₁/FVC < 70% post-bronchodilator. |
| "Airway &/or alveolar abnormalities" | Two components: chronic bronchitis (airway) and emphysema (alveolar). |
| "Noxious particles or gases" | Smoking is by far #1, but also air pollution, biomass fuels, occupational dusts. |
| "Exacerbations and comorbidities" | These drive hospitalisation and mortality, not just the baseline lung function. |
2. Pathophysiology — Mechanisms of Airflow Limitation
The lecture explicitly teaches two mechanisms underlying airflow limitation: [1]
- Airway inflammation → mucosal oedema, neutrophilic infiltration
- Airway fibrosis, luminal plugs → structural narrowing of airways < 2mm diameter
- Increased airway resistance → harder to move air, especially on expiration
- Loss of alveolar attachments → the alveoli normally tether small airways open; when alveoli are destroyed, airways collapse during expiration
- Decrease of elastic recoil → the lung loses its ability to passively exhale; air gets trapped
Why does this matter? Because these two mechanisms explain everything downstream:
- Air trapping → hyperinflation → barrel chest, flattened diaphragm on CXR
- Destroyed alveoli → reduced gas exchange surface → low DLCO → hypoxaemia
- Chronic hypoxaemia → pulmonary vasoconstriction → pulmonary hypertension → cor pulmonale
"CB – chronic bronchitis: chronic cough + sputum" "E – emphysema: progressive dyspnoea"
Most COPD patients have a mixture of both, but the lecture deliberately shows them as overlapping circles (Venn diagram). Classic "blue bloater" (chronic bronchitis-predominant) vs "pink puffer" (emphysema-predominant) are old terms but the concepts still help you understand the spectrum.
| Feature | Chronic Bronchitis Predominant | Emphysema Predominant |
|---|---|---|
| Definition | Productive cough ≥3 months/year for ≥2 consecutive years | Permanent destructive enlargement of airspaces distal to terminal bronchioles |
| Main symptom | Chronic cough + sputum | Progressive dyspnoea |
| Body habitus | Overweight ("bloater") | Cachectic ("puffer") |
| Cyanosis | Common (V/Q mismatch) | Less common (maintains ventilation) |
| CO₂ retention | Early | Late |
"Affects ~10% of Hong Kong elderly > 70 years old; overall occupied ~10% public medical bed days; expected increasing incidence because of smoking and worsening air pollution — a very common medical condition!" [1]
This is exam-relevant because it establishes COPD as a major public health burden in Hong Kong. If asked "why is COPD important?", cite these figures.
4. Risk Factors
The lecture lists risk factors divided into Environmental Factors and Host Factors: [1]
| Factor | Notes |
|---|---|
| Cigarette smoking | "By far the most important factor accounting for > 85% patients" [1] |
| Air pollution | Outdoor particulate matter |
| Passive smoking | Second-hand smoke exposure |
| Indoor biomass combustion | "e.g. wood — especially women in rural regions/countries" [1] — this explains why non-smoking women in developing countries get COPD |
| Factor | Notes |
|---|---|
| α₁-antitrypsin (AAT) deficiency | "Rare; consider it when we see a young patient with emphysema (e.g. < 45 yr old, esp Caucasians)" [1] |
First-principles explanation of AAT deficiency: α₁-antitrypsin is a protease inhibitor produced by the liver that protects lung tissue from neutrophil elastase. In smokers, neutrophils flood the lung and release elastase → AAT neutralises it. If AAT is deficient (PiZZ phenotype), elastase destroys alveolar walls unchecked → panacinar emphysema, predominantly basal (cf. smoking-related emphysema which is centrilobular and upper-zone predominant). It classically presents in young Caucasians with emphysema who may or may not smoke.
Exam Trap: AAT Deficiency
Don't confuse centrilobular emphysema (smoking, upper lobes) with panacinar emphysema (AAT deficiency, lower lobes). If you're given a young non-smoker or light smoker with emphysema, think AAT deficiency.
5. Clinical Presentations
"Typically: Middle age / elderly, men > women; Nearly always Hx of chronic smoking; Chronic cough and sputum: years! (usually whitish and mucoid unless exacerbations) – (CB); Progressive shortness of breath – (E); Features of Complications → hospitalization" [1]
- Smoking history: Always quantify in pack-years = (packs/day) × (years smoked). A "chronic smoker of one pack per day since teenage" (as in the 2024 SAQ [7]) is roughly 40+ pack-years.
- Cough character: Chronic, productive, worse in the morning (increased cholinergic tone overnight [3]), whitish/mucoid sputum at baseline. Change to purulent/green sputum = infective exacerbation.
- Dyspnoea: Progressive, initially exertional, eventually at rest. Grade using mMRC dyspnoea scale [2]:
| mMRC Grade | Description | Memory Aid |
|---|---|---|
| 0 | SOB only during strenuous exercise | |
| 1 | SOB when walking uphill | 斜 (slope) |
| 2 | Walks slower than peers due to SOB | 慢 (slow) |
| 3 | Stops for breath after walking a few minutes | 分 (minutes) |
| 4 | Too breathless to leave the house | 街 (street) |
- Exacerbation history: How many per year? Required hospitalisation? Required NIV/ICU?
- Occupational history: Construction worker, mining, biomass exposure
- Comorbidities: Cardiac disease, depression, osteoporosis (see Section 11)
General inspection:
- Cyanosis (central → severe hypoxaemia)
- Nicotine staining of fingers [1]
- Use of accessory muscles (sternocleidomastoid, scalenes)
- Pursed-lip breathing (creates auto-PEEP to keep airways open)
- Cachexia (in advanced emphysema)
Chest:
- Barrel chest (increased AP diameter from hyperinflation)
- Reduced chest expansion (hyperinflated lungs can't expand further)
- Hyper-resonant percussion (air-filled)
- Reduced breath sounds (poor air entry)
- Wheeze (airway narrowing)
- Prolonged expiratory phase
Signs of complications:
- Cor pulmonale: raised JVP, parasternal heave (RVH), ankle oedema, loud P2, hepatomegaly [1]
- Asterixis/flapping tremor (CO₂ retention)
- Bounding pulse, warm peripheries (CO₂ retention → vasodilation)
6. Complications of COPD
The lecture provides a diagram showing: Chronic hypoxaemia → Pulmonary hypertension → RVH & RVF
Here's the logic chain:
- Destroyed alveoli + V/Q mismatch → chronic hypoxaemia
- Hypoxaemia → hypoxic pulmonary vasoconstriction (Euler-Liljestrand reflex — pulmonary arterioles constrict in response to low alveolar PO₂ to redirect blood to better-ventilated areas)
- When hypoxaemia is global (as in severe COPD), vasoconstriction is diffuse → pulmonary hypertension
- RV pumps against high pulmonary pressure → RV hypertrophy (RVH)
- Eventually RV fails → right ventricular failure (RVF) = cor pulmonale
"Pulmonary HT → RV suffers; cf. Systemic HT → LV suffers" [1]
Signs of cor pulmonale (from the diagram) [1]:
- Raised JVP (back-pressure from failing RV)
- Ankle oedema (systemic venous congestion)
- Parasternal heave (RVH)
- Note: Pulmonary oedema is NOT typically a feature (that's LVF)
Management of cor pulmonale [1]:
- Diuretics (offload fluid)
- Salt & fluid restriction
- Long-term oxygen therapy (treats the underlying cause — hypoxaemia)
- Acute exacerbation (see Section 9)
- Pulmonary thromboembolism [1] — immobility + polycythaemia + inflammation = prothrombotic state
- Secondary polycythaemia — chronic hypoxaemia → EPO release → elevated haematocrit (>55%)
- Respiratory failure (Type I or Type II)
- Pneumothorax — bullae rupture
7. Investigations
The lecture lists: [1]
| Investigation | What You're Looking For | Why |
|---|---|---|
| Lung function test (Spirometry) | FEV₁/FVC < 70% (airflow obstruction); ↑RV & TLC (hyperinflation); ↓DLCO (alveolar destruction — emphysema) | This is the diagnostic test. FEV₁/FVC < 70% post-bronchodilator confirms COPD. DLCO distinguishes COPD from asthma (DLCO normal in asthma). |
| Complete blood counts | Polycythaemia (↑Hct, ↑Hb) | Secondary polycythaemia from chronic hypoxaemia |
| Chest X-ray | Hyperinflation (>6 anterior ribs visible, flattened diaphragm, increased retrosternal airspace); Hypertranslucency (dark lungs from destroyed alveoli and air trapping) | Also look for cardiomegaly + prominent pulmonary arteries if cor pulmonale |
| Arterial blood gases | Type I (↓PaO₂, normal/↓PaCO₂) or Type II respiratory failure (↓PaO₂, ↑PaCO₂) | Essential for assessing severity and guiding oxygen therapy |
| Sputum examination | Culture & sensitivity during exacerbations | Identify causative organism for targeted antibiotics |
| ECG ± Echocardiogram | P pulmonale (peaked P waves in II), right axis deviation, RVH, RVSP elevation | Assess for cor pulmonale |
The lecture shows two CXR slides:
- Uncomplicated COPD: Hyperinflation + hypertranslucency
- COPD complicated by pulmonary hypertension & cor pulmonale: Hyperinflation + hypertranslucency + cardiomegaly + prominent pulmonary arteries [1]
| GOLD Stage | FEV₁ (% predicted, post-bronchodilator) |
|---|---|
| GOLD 1 (Mild) | ≥ 80% |
| GOLD 2 (Moderate) | 50–79% |
| GOLD 3 (Severe) | 30–49% |
| GOLD 4 (Very severe) | < 30% |
Key point: FEV₁/FVC < 70% must be present first to diagnose COPD, THEN you grade severity by FEV₁ % predicted.
| Feature | COPD | Chronic Asthma | Bronchiectasis |
|---|---|---|---|
| Smoking | Nearly always | Usually non-smokers | Usually non-smokers |
| Age of onset | Middle age/elderly | Often childhood | Often childhood/young |
| Symptoms | Persistent, progressive | Episodic, with symptom-free intervals | Chronic productive cough |
| Sputum | Mucoid (unless exacerbation) | Usually minimal | Purulent, large volume, foul-smelling |
| Clubbing | Absent | Absent | Present |
| Reversibility | Incomplete (<12% or <200mL improvement post-BD) | Significant (≥12% AND ≥200mL) | Variable |
| DLCO | ↓ (if emphysema) | Normal | Normal or ↓ |
| CXR | Hyperinflation, hypertranslucency | Usually normal between attacks | Tramlines, ring shadows |
8. Management of Stable COPD
The lecture outlines a Management Program: [1]
- Assess and monitor disease
- Reduce risk factors: stop smoking
- Manage stable COPD: Bronchodilator (BD), Inhaled Corticosteroids (ICS), Long-term Oxygen Therapy (LTOT), Rehabilitation
- Manage exacerbation: Controlled oxygen therapy, Antibiotics, Systemic steroid, Non-invasive Ventilation (NIV)
- End stage COPD: Lung Volume Reduction Procedures / Lung Transplantation
- The ONLY intervention proven to alter the natural history of COPD (i.e. slow the decline in FEV₁)
- See Section 10 for detailed smoking cessation pharmacology
"Bronchodilators (BD): Anti-cholinergics, β₂ agonists. Anti-inflammatory Rx: Inhaled corticosteroids (ICS); New oral phosphodiesterase inhibitor (Roflumilast) — when frequent exacerbations. Inhaled preferred." [1]
| Drug Class | Short-Acting (Relief) | Long-Acting (Maintenance) | Mechanism |
|---|---|---|---|
| β₂ agonists | Salbutamol (Ventolin), Terbutaline (Bricanyl) | Salmeterol (Serevent), Formoterol (Oxis) | Stimulate β₂ receptors → bronchial smooth muscle relaxation → bronchodilation |
| Anti-cholinergics | Ipratropium (Atrovent) | Tiotropium (Spiriva) | Block muscarinic (M3) receptors → prevent ACh-mediated bronchoconstriction → bronchodilation |
| ICS | — | Beclomethasone (Becotide/Becloforte), Budesonide (Pulmicort), Fluticasone (Flixotide) | Reduce airway inflammation → reduce exacerbation frequency (but DON'T slow lung function decline) |
| PDE4 inhibitor | — | Roflumilast (Daxas) | "A new oral non-steroid anti-inflammatory therapy specific for COPD" [1] — inhibits PDE4 → ↑cAMP → anti-inflammatory. Used when FEV₁ <50% + chronic bronchitis phenotype [2] |
ICS in COPD — Important Nuance
Unlike asthma where ICS is the cornerstone, in COPD, ICS is added for patients with frequent exacerbations (≥2 moderate or ≥1 requiring hospitalisation per year), especially if blood eosinophils ≥300 or concomitant asthma features. Regular ICS use in COPD increases risk of pneumonia [2]. This is a major exam discriminator between COPD and asthma management.
"Exercise Training: Improves muscle function and increases exercise tolerance; Reduces dyspnoea; Improves quality of life" [1]
Pulmonary rehabilitation is a multidisciplinary programme including:
- Physiotherapy and exercise training
- Nutritional support ("for cachexia" [1])
- Education and psychotherapy
- Breathing techniques
This is a non-pharmacological intervention that is frequently tested in SAQs [2].
Criteria for LTOT in COPD: [1]
- "Resting PaO₂ < 7.3 kPa by two separate measurements when breathing room air in stable condition on optimal medical treatment"
- "Resting PaO₂ < 8 kPa (i.e. relaxing the criteria) when in addition the patient has:
- Secondary polycythaemia (haematocrit > 55%)
- Cor pulmonale
- Pulmonary hypertension
- Nocturnal hypoxaemia"
Why two different thresholds? Because at PaO₂ < 7.3 kPa, the patient is severely hypoxic regardless of complications. At 7.3–8 kPa, oxygen is still warranted if there's evidence that hypoxaemia is already causing end-organ damage (polycythaemia, cor pulmonale, pulmonary HT) or if nocturnal desaturation accelerates complications.
Practical points from the lecture [1]:
- Goal: SaO₂ > 90%
- May increase flow during exercise & sleep
- Duration: at least 16–18 hours/day including bedtime (this was tested in 2022 MCQ [6] — answer A is correct)
- Delivered via O₂ concentrator ("an electrical appliance; a molecular sieve that takes and concentrates O₂ from air → non-stop supply; patient can buy or rent" [1])
- Portable O₂ concentrators now available: 1–2 kg, batteries for 3 hours (bigger up to 10 hours), enables patients to travel [1]
2022 MCQ: LTOT Duration
Q: A 75-year-old man with COPD was advised home oxygen therapy. What is the MOST APPROPRIATE therapy? A: Home oxygen therapy at least 16–18 hours a day including bedtime [6]. NOT just at night, NOT just during exercise, NOT prn.
2024 MCQ: Cor Pulmonale and Survival Benefit
Q: A 68-year-old man with COPD has features of cor pulmonale, SaO₂ 90% on room air. Which contributes the BEST survival benefit? A: Long-term oxygen therapy [7]. LTOT is the only intervention (besides smoking cessation) shown to improve survival in COPD with chronic hypoxaemia. In cor pulmonale, LTOT addresses the root cause (hypoxic pulmonary vasoconstriction).
9. Management of Acute Exacerbation of COPD (AECOPD)
"Management of complications — which account for most of the hospitalizations & mortality" [1]
- Infection (~70%): viral (rhinovirus, influenza) or bacterial
- Air pollution
- Unknown (~30%)
Management of AECOPD (from lecture) [1]
Controlled O₂ therapy; Exclude and treat pneumothorax; Systemic corticosteroid; ↑Inhaled bronchodilators; Antibiotics for infections; Non-invasive ventilation for decompensated type II respiratory failure [1]
"Aim: to use O₂ in a controlled manner to achieve a target PaO₂ of 8 kPa (SaO₂ > 90%) without significant CO₂ retention or acidosis" [1]
Why "controlled"? In COPD patients with chronic CO₂ retention (Type II respiratory failure), the central chemoreceptors become desensitised to CO₂. The remaining respiratory drive comes from peripheral chemoreceptors responding to hypoxaemia. If you give too much O₂ and abolish the hypoxic drive, ventilation drops → CO₂ rises further → narcosis → respiratory arrest.
Modes: Nasal cannula (1–2 L/min); Venturi mask (24%, 28%) [1]
Venturi masks deliver a precise FiO₂ regardless of respiratory pattern — this is why they're preferred in COPD exacerbations over simple face masks (which deliver variable and often excessive FiO₂).
Monitor: Clinical (conscious levels, blood pressure, pulses); Pulse oximetry; Arterial blood gas measurement [1]
Target saturation in COPD: 88–92% (unlike most other conditions where you target 94–98%).
Exam Trap: Oxygen in COPD
Never give high-flow uncontrolled oxygen to a COPD patient without monitoring. Always start low (24–28% Venturi or 1–2L nasal cannula), check ABG within 30–60 minutes, and titrate. The target is SaO₂ 88–92%, NOT 94–98%.
"Commonest sputum bacterial isolates: Haemophilus influenzae, Streptococcus pneumoniae, Moraxella catarrhalis, (Pseudomonas aeruginosa)" [1]
Pseudomonas is in brackets because it's more relevant in severe/frequent exacerbators and those with bronchiectasis overlap.
"Choice of empirical antibiotics is usually clinical, basing on knowledge of local bacterial & resistance pattern" [1] Examples: augmentin, macrolide, cephalosporin [1]
When to give antibiotics? When sputum becomes purulent (Anthonisen criteria: increased dyspnoea + increased sputum volume + increased sputum purulence → if 2/3 present and one is purulence → antibiotics indicated).
Short course of oral prednisolone (typically 30–40 mg for 5 days) or IV hydrocortisone in severe cases. Reduces inflammation, speeds recovery, reduces treatment failure.
"NIV for COPD Type II Respiratory Failure — tightly fit to minimize air leak; no intubation, hence 'non-invasive'; intubation & IPPV when NIV fails" [1]
Indication: Decompensated Type II respiratory failure (pH < 7.35, PaCO₂ > 6 kPa) despite controlled oxygen and initial medical treatment.
How NIV works: Bilevel positive airway pressure (BiPAP) provides:
- IPAP (inspiratory positive airway pressure) → augments tidal volume → improves alveolar ventilation → washes out CO₂
- EPAP (expiratory positive airway pressure) → splints airways open → counteracts auto-PEEP → reduces work of breathing
Failure of NIV → intubation and invasive positive pressure ventilation (IPPV).
10. Smoking Cessation
"> 4,000 chemicals; > 40 carcinogens; Nicotine (addiction → brain); CO (heart)" [1]
"Addiction, stimulation; Atherosclerosis (hardening); Stimulation (adrenaline & NA); Nicotine nail staining — Important in Smoking cessation" [1]
Nicotine acts on nicotinic acetylcholine receptors (nAChR) in the brain, particularly in the mesolimbic dopamine pathway (ventral tegmental area → nucleus accumbens). It releases dopamine → reward → reinforcement → addiction. This is why smoking cessation is so difficult — it's not just a "habit", it's a neurochemical addiction.
"Fletcher's graph: Decline of FEV₁ with age and smoking habits — It's never too late to quit" [1]
This is a classic, high-yield graph. Key points:
- Non-smokers lose FEV₁ gradually with age (normal ageing)
- Susceptible smokers lose FEV₁ much faster → cross the disability/death threshold earlier
- If you quit smoking at any point, the rate of FEV₁ decline returns towards that of non-smokers (you don't regain lost function, but you stop the accelerated loss)
- This is why the lecture says "it's never too late to quit" — even in established COPD, quitting improves prognosis
The lecture mentions withdrawal symptoms include:
- Craving
- Coughing
- Hunger / weight gain
- Bowel disturbance
- Sleep disturbance
- Dizziness
- Paraesthesia
- Mood swings, irritability
- Lack of concentration [3]
Three options:
- Nicotine — gum, patch, inhaler
- Bupropion SR (Zyban/Wellbutrin SR) — antidepressant with specific use in smoking cessation
- Varenicline (Champix) — acts at the same receptor in the brain as nicotine (ACh receptor) — dual action: ↓withdrawal S/S when quitting; blocks the reinforcing effects of nicotine when smoking
Plus: health care professional counselling; social support by family & friends
"Success rate at 1 year only about 20–35%! Efficacy: Varenicline: best" [1]
| Agent | Mechanism | Key Points |
|---|---|---|
| Nicotine replacement | Provides nicotine without the harmful chemicals in smoke → reduces withdrawal symptoms | Gum, patch, inhaler, nasal spray. Still has nicotine side effects. |
| Bupropion (Zyban) | NE-DA reuptake inhibitor + nicotinic antagonist [3] | An antidepressant repurposed for smoking cessation. Reduces craving and withdrawal. CI: seizure history. |
| Varenicline (Champix) | Partial agonist at α₄β₂ nAChR | Dual action: (1) Provides partial stimulation of receptor → reduces withdrawal; (2) Blocks nicotine from fully activating receptor → smoking is less rewarding if patient relapses. BEST efficacy [1]. |
Efficacy ranking: Varenicline > Bupropion > Nicotine replacement [1][3]
2022 MCQ: Best Smoking Cessation Option
Q: A 55-year-old chronic heavy smoker with severe CAD on waitlist for coronary intervention consulted for smoking cessation. What is the BEST option? A: Counselling plus Varenicline [6]. Varenicline has the best efficacy. Note that counselling is always part of the answer — pharmacotherapy alone is never the answer.
Reasons people smoke:
- Overlearnt habit, association/secondary reinforcement
- Routine, social-peer pressure
- Craving / addiction (nicotine)
- Stress relief, relaxation
Potential motivators for cessation:
- Save money
- Social acceptability
- Not harm others (passive smoking)
- Improve health
- Better taste and smell
- Reduce fire hazard
Key counselling principle: Allow the smoker to find a personal reason for quitting [3]. This is more effective than lecturing.
The 2016 SAQ asked about the six MPOWER measures:
- M — Monitor tobacco use and prevention policies
- P — Protect people from tobacco smoke
- O — Offer help to quit tobacco use
- W — Warn about the dangers of tobacco
- E — Enforce bans on tobacco advertising, promotion, sponsorship
- R — Raise taxes on tobacco
The lecture lists common comorbidities in COPD: [1]
This was directly tested in the 2024 SAQ [7]: "Name five cardiorespiratory co-morbid conditions" and "Name five non-cardiorespiratory co-morbid conditions."
| Cardiorespiratory | Non-Cardiorespiratory |
|---|---|
| Cardiovascular disease (CVD) | Osteoporosis |
| Heart failure | Anxiety and depression |
| Ischaemic heart disease (IHD) | Metabolic syndrome and diabetes |
| Arrhythmias | Gastroesophageal reflux (GERD) |
| Peripheral vascular disease | Obstructive sleep apnea |
| Hypertension | |
| Lung cancer | |
| Bronchiectasis |
Why so many comorbidities? COPD is a systemic inflammatory disease. Chronic inflammation, physical inactivity, smoking, and steroid use all contribute. For example:
- Smoking → atherosclerosis → IHD, PVD, stroke
- Systemic inflammation → metabolic syndrome, diabetes
- Corticosteroid use + inactivity → osteoporosis
- Chronic illness + breathlessness + social isolation → anxiety and depression
- Smoking → lung cancer (COPD itself is an independent risk factor for lung cancer)
- GERD → microaspiration → exacerbations
"End stage COPD: Lung Volume Reduction Procedures / Lung Transplantation" [1]
- Lung Volume Reduction Surgery (LVRS): Removes the most diseased, hyperinflated portions of lung → allows remaining lung to expand better → improves diaphragm mechanics. Best for upper-lobe-predominant emphysema with low exercise capacity.
- Lung transplantation: For highly selected patients with very severe COPD refractory to all other treatments.
Likely Exam Questions
-
A 70-year-old COPD patient with cor pulmonale. SaO₂ 89% on room air. What gives the best survival benefit? → LTOT (must be ≥16–18 hrs/day)
-
Best pharmacological agent for smoking cessation? → Varenicline (Champix) — best efficacy; acts as partial agonist at nicotinic ACh receptor
-
Target SaO₂ in COPD exacerbation? → 88–92%
-
Young Caucasian with basal emphysema, non-smoker. What host factor? → α₁-antitrypsin deficiency
-
Spirometry: FEV₁/FVC 55%, FEV₁ 45% predicted, minimal bronchodilator reversibility. Diagnosis? → COPD, GOLD 3 (severe)
-
Name 5 cardiorespiratory and 5 non-cardiorespiratory comorbidities of COPD. (2024 SAQ) [7] → See Section 11 table
-
Name the criteria for LTOT in COPD. → PaO₂ < 7.3 kPa (×2 measurements, stable, on room air, optimal Rx) OR PaO₂ < 8 kPa with polycythaemia/cor pulmonale/pulmonary HT/nocturnal hypoxaemia
-
Interpret spirometry showing FEV₁/FVC 60%, FEV₁ 60% predicted, minimal post-BD change. (2023 Minicase) [8] → Obstructive pattern (FEV₁/FVC < 70%); moderate severity (GOLD 2); incomplete reversibility → consistent with COPD
-
65-year-old retired construction worker, 50 pack-year smoker, 1-month cough. Give 5 differential diagnoses. (2022 Minicase) [6] → COPD, lung cancer, TB, bronchiectasis, pneumonia / heart failure
-
Same patient develops facial/neck swelling, dilated chest wall veins, right hilar mass. What is this acute condition? (2022 Minicase) [6] → Superior vena cava obstruction (SVCO) from lung cancer
- GC 077 (Pleural effusion in a chronic smoker) [9]: The same population of chronic smokers may present with lung cancer → pleural effusion. Always consider malignancy in the differential of a smoker with new respiratory symptoms.
- GC 052 (Fever and purulent sputum) [10]: COPD patients are prone to community-acquired pneumonia (H. influenzae, S. pneumoniae). Know the overlap between AECOPD and pneumonia.
- GC 084 (Shortness of breath on exertion) [11]: Heart failure is a major differential and comorbidity of COPD. Both cause exertional dyspnoea. Look for orthopnoea, PND, bilateral basal crackles (HF) vs barrel chest, wheeze, hyperinflation (COPD).
- CFB MED03 (Respiratory System) [12]: Cough classification — acute (days: URTI, pneumonia), subacute (weeks: TB, lung cancer), chronic (years: COPD, bronchiectasis, asthma).
High Yield Summary
COPD = persistent airflow limitation (FEV₁/FVC < 70% post-BD) due to small airway disease + parenchymal destruction, almost always from smoking (>85%). Clinical presentation: middle-aged/elderly smoker with chronic cough + sputum (CB) and progressive dyspnoea (emphysema). Complications: cor pulmonale (chronic hypoxaemia → pulmonary HT → RVF), respiratory failure, pneumothorax, polycythaemia.
Investigations: Spirometry (diagnostic), CXR (hyperinflation, hypertranslucency), CBC (polycythaemia), ABG (respiratory failure), ECG/echo (cor pulmonale). DLCO ↓ in emphysema (distinguishes from asthma).
Management: (1) Smoking cessation — the ONLY intervention that alters natural history; Varenicline is most effective; (2) Bronchodilators (anti-cholinergics + β₂ agonists); (3) Add ICS for frequent exacerbators; (4) Pulmonary rehabilitation; (5) LTOT if PaO₂ < 7.3 kPa (or < 8 kPa with complications) — ≥16–18 hrs/day — improves survival.
AECOPD: Controlled O₂ (target 88–92%), nebulised BD, systemic steroids, antibiotics (H. influenzae, S. pneumoniae, M. catarrhalis), NIV for decompensated Type II RF.
Comorbidities: CVD, IHD, HF, lung cancer, osteoporosis, depression, diabetes, GERD, OSA — frequently examined (2024 SAQ).
Active Recall - COPD & Smoking Cessation
[1] Lecture slides: GC 041. Cough in a chronic smoker_COPD; smoking cessation.pdf [2] Senior notes: Maksim Medicine Notes.pdf (Respiratory medicine section) [3] Senior notes: Ryan Ho Respiratory.pdf (Management of COPD, Smoking cessation) [4] Senior notes: MBBS Final MB (Medicine) (Felix PY Lai).pdf (COPD differential diagnosis section) [5] Past papers: 2016 Fourth Summative SAQ.pdf (Question 11 - MPOWER) [6] Past papers: 2022 Fourth Summative MCQ.pdf (Questions 44, 45); 2022 Fourth Summative Minicase.pdf (Case Three); 2022 Fourth Summative SAQ.pdf (Question 6) [7] Past papers: 2024 Fourth Summative SAQ.pdf (Question 4); 2024 Fourth Summative MCQ.pdf (Question 34) [8] Past papers: 2023 Fourth Summative Minicase.pdf (Case One) [9] Lecture slides: GC 077. Pleural effusion in a chronic smoker.pdf [10] Lecture slides: GC 052. Fever and purulent sputum.pdf [11] Lecture slides: GC 084. Shortness of breath on exertion.pdf [12] Lecture slides: CFB (MED03) Respiratory System.pdf
GC040 Cough And Wheezing: Asthma And Allergic Lung Diseases
Asthma and allergic lung diseases are chronic inflammatory airway disorders characterized by reversible bronchoconstriction, mucus hypersecretion, and airway hyperresponsiveness, presenting with episodic cough, wheezing, and dyspnea triggered by allergens or irritants.
GC042 Deterioration Of Eyesight In A Diabetic Patient Diabetic Complications
Progressive visual impairment in a diabetic patient resulting from complications such as diabetic retinopathy, macular edema, or accelerated cataract formation due to chronic hyperglycemia-induced microvascular and lens damage.