Chronic Lung Diseases in Primary Care

Learning Objectives

• Understand the indications and interpretation of spirometry in primary care
• Recognise and manage bronchiectasis and post-TB lung disease (PTLD)
• Diagnose and manage asthma according to GINA 2024 guidelines
• Diagnose and manage COPD using the GOLD 2024 ABE framework
• Identify when to suspect interstitial lung disease (ILD) and initiate referral
• Apply Singapore MOH ACE 2024 recommendations in clinical practice

Bronchodilator Reversibility Testing

• Administer 200-400 mcg salbutamol via MDI + spacer
• Withhold SABA ≥4h, LABA 24-48h before test for diagnostic accuracy
• Repeat spirometry 10-15 minutes after bronchodilator
• Positive (adults): FEV₁ or FVC increase ≥12% AND ≥200 mL
• Greater confidence: ≥15% increase and ≥400 mL
• 💎 Positive reversibility suggests asthma but does NOT exclude COPD (or confirm ACO)

Bronchiectasis & PTLD: Management

• Goals: reduce symptom burden, improve QoL, decrease exacerbations, prevent progression
• Airway clearance: physiotherapy, huffing/coughing techniques, oscillating PEP devices
• Long-term macrolides (azithromycin): reduces exacerbation frequency in RCTs
• Inhaled antibiotics (e.g., tobramycin, colistin): for chronic Pseudomonas colonization
• Vaccinations: pneumococcal + influenza (essential for all patients)
• 💎 Pulmonary rehabilitation and smoking cessation are key for PTLD management

Asthma: Definition & Phenotypes (GINA 2024)

• Heterogeneous disease with chronic airway inflammation
• Defined by: variable respiratory symptoms (wheeze, SOB, chest tightness, cough) + variable expiratory airflow limitation
• Allergic asthma: most common; childhood onset, atopy, eosinophilic, responds well to ICS
• Non-allergic asthma: sputum neutrophilic/eosinophilic/paucigranulocytic
• Adult-onset asthma: often non-allergic; rule out occupational asthma
• Obesity-associated asthma: prominent symptoms, little eosinophilic inflammation

Asthma: Making the Diagnosis

• Requires BOTH: (1) characteristic variable symptom pattern AND (2) confirmed variable airflow limitation
• Symptoms: wheeze, SOB, chest tightness, cough — vary over time and intensity
• Often worse at night/morning; triggered by exercise, allergens, cold air, viral infections
• Confirm with spirometry: positive BD reversibility (FEV₁ ≥12% + ≥200 mL) or PEF variability >10%/day
• If initial tests negative — repeat during symptoms or early morning
• 💎 Do NOT start long-term treatment without objective evidence of variable airflow limitation

Asthma Diagnostic Criteria (GINA 2024)

• Positive BD reversibility: FEV₁ ≥12% + ≥200 mL (adults); FEV₁ ≥12% predicted (children)
• PEF variability >10%/day (adults) or >13%/day (children) over 2 weeks
• Increase in FEV₁ ≥12% + ≥200 mL after 4 weeks of ICS treatment
• Positive methacholine challenge: FEV₁ fall ≥20%
• Variation in FEV₁ ≥12% + ≥200 mL between visits
• 💎 The more tests are positive and the more often they are positive, the more confident the diagnosis

Asthma: Differential Diagnosis

• Children 6-11: Upper airway cough syndrome, inhaled foreign body, bronchiectasis, CF, congenital heart disease
• Adolescents/Adults: Inducible laryngeal obstruction (stridor, not wheeze), hyperventilation
• All ages: COPD (older smokers), cardiac failure (orthopnoea, PND), ACE inhibitor cough
• Constitutional symptoms (fever, night sweats, weight loss) → consider TB
• 💎 Asthma-COPD Overlap (ACO) exists — look for features of both
• Comorbidities (rhinosinusitis, GERD, obesity, OSA) can coexist AND worsen asthma control

Asthma Medications: Key Terminology

• Controller: ICS-containing medication for regular daily use (targets inflammation AND risk)
• Reliever: As-needed inhaler for quick symptom relief (salbutamol, ICS-formoterol)
• Anti-inflammatory Reliever (AIR): Low-dose ICS + rapid-acting BD (budesonide-formoterol)
• MART (Maintenance-And-Reliever Therapy): ICS-formoterol for BOTH maintenance AND relief
• 💎 Only specific ICS-formoterol combinations can be used as MART (NOT salmeterol, vilanterol etc.)
• LTRA (e.g., montelukast): Alternative add-on controller; less effective than ICS for exacerbation prevention

Inhaler Technique: Pearls

• Poor inhaler technique is a leading cause of uncontrolled asthma
• MDI: shake → breathe out fully → slow deep breath in while pressing → hold 10 sec
• DPI (Turbuhaler/Accuhaler): fast forceful inhalation required; do NOT exhale into device
• Spacer: increases lung deposition from MDI by 2-3x; essential for children and patients with poor coordination
• 💎 Always demonstrate technique AND ask patient to show you back ('teach-back')
• Reassess technique at EVERY consultation — errors recur even after correct initial training

Acute Asthma: Severity Classification

Acute Asthma: Primary Care Management

Acute Asthma: ED Management

Asthma in Children ≤5 Years: Diagnosis

• Challenging — episodic wheeze and cough common in this age group
• More likely asthma if: recurrent symptoms, worse at night, triggered by exercise/allergens/viral URTI
• Trial of treatment: response to short-term low-dose ICS supports diagnosis
• Differential: recurrent viral wheeze (no atopy, well between episodes), GERD, foreign body, pertussis, bronchiectasis
• 💎 Consider referral to paediatrician if: <1 year old, atypical symptoms, poor treatment response
• Do NOT use peak flow meters in children <5 years (cannot reliably perform manoeuvre)

Asthma in Children ≤5 Years: Management

• Reliever: Salbutamol 200-400 mcg via MDI+spacer (with mask if <4 years) q20min for acute episodes
• Step 1: As-needed SABA only for infrequent wheeze
• Step 2: Daily low-dose ICS (budesonide 200 mcg/day) OR daily montelukast if ICS not feasible
• Step 3: Increase ICS dose OR add montelukast; consider specialist referral
• Step 4: Specialist referral for further evaluation and management
• 💎 MDI + spacer + face mask is the preferred delivery device for children under 4 years

Paediatric Inhaler Technique & ICS Dosing

• Always use spacer with MDI for children — face mask for <4 years, mouthpiece for ≥4 years
• Low-dose ICS in children: Budesonide 100-200 mcg/day; BDP 100-200 mcg; FP 50-100 mcg
• Wash and air-dry spacer weekly — detergent reduces electrostatic charge improving drug delivery
• Counsel parents: ICS at appropriate doses do NOT stunt growth significantly when benefits outweigh risks
• 💎 Demonstrate pMDI + spacer + mask technique to both parent AND child at every visit
• Video resources: National Asthma Council Australia website has age-specific inhaler technique guides

COPD: Definition & Risk Factors

• Heterogeneous lung condition — persistent airflow obstruction from airway (bronchitis/bronchiolitis) and/or alveolar (emphysema) abnormalities
• Key symptoms: chronic dyspnoea (especially exertional), cough, sputum production
• Leading global cause of morbidity and mortality; often underdiagnosed
• Risk factors: TOBACCO SMOKE (most important), household/outdoor air pollution, occupational dusts/chemicals
• Alpha-1-antitrypsin deficiency: rare genetic cause — suspect in non-smokers or early-onset COPD
• Early life events: prematurity, low birth weight, childhood respiratory infections also contribute

COPD vs Asthma: Key Differences

• COPD: usually ≥40 years; persistent/progressive dyspnoea; significant smoking/exposure history
• Asthma: any age; variable episodic symptoms; personal/family history of atopy; triggers
• COPD: persistent post-BD obstruction (FEV₁/FVC <0.70); minimal reversibility
• Asthma: often normal lung function between episodes; significant reversibility (≥12% + ≥200 mL)
• 💎 Asthma-COPD Overlap (ACO): features of both; eosinophilia + BD reversibility; treat with ICS + LABD
• Chest X-ray: COPD may show hyperinflation, flat diaphragms; asthma usually normal

COPD Assessment Tools: mMRC & CAT

• mMRC Grade 0: Breathless only with strenuous exercise
• mMRC Grade 1: Short of breath when hurrying or walking up a slight hill
• mMRC Grade 2: Walks slower than others due to breathlessness, or stops to rest
• mMRC Grade 3: Stops for breath after ~100m on flat ground
• mMRC Grade 4: Too breathless to leave house; breathless when dressing/undressing
• 💎 CAT score ≥10 = significant symptom burden; use CAT for more comprehensive assessment

COPD Clinical Phenotypes

• ACO (Asthma-COPD Overlap): High eosinophils, BD reversibility — ICS is essential
• Frequent Exacerbator: ≥2 moderate or ≥1 severe/year — LABA+LAMA ± ICS; consider roflumilast/azithromycin
• Emphysema-predominant: CT emphysema, hyperinflation, low BMI — consider lung volume reduction
• Chronic Bronchitis: Productive cough ≥3 months × 2 years — mucolytics, roflumilast
• Physical Frailty (gait speed <0.8 m/s): Pulmonary rehab with strength training
• 💎 Identify predominant phenotype to guide personalised management beyond ABE grouping

COPD Inhalers Available in Singapore

• SABA: Salbutamol (Ventolin), Terbutaline (Bricanyl) — short-acting, for rescue
• SAMA: Ipratropium (Atrovent) — short-acting antimuscarinic, useful in acute exacerbations
• LAMA: Tiotropium (Spiriva HandiHaler/Respimat), Umeclidinium (Incruse), Glycopyrronium (Seebri)
• LAMA+LABA: Umeclidinium-vilanterol (Anoro), Tiotropium-olodaterol (Spiolto), Glycopyrronium-formoterol (Bevespi)
• LABA+ICS or LAMA+LABA+ICS: e.g., Fluticasone-salmeterol (Seretide), Fluticasone furoate-vilanterol-umeclidinium (Trelegy)
• 💎 Do NOT combine two inhalers from the same drug class (e.g., two LAMAs) — no added benefit, increased risk

COPD: Comorbidities

• Cardiovascular disease: most common comorbidity; increases mortality independently
• 💎 Beta-blockers are NOT contraindicated in COPD — use for appropriate cardiac indications (heart failure, post-MI)
• Lung cancer: 4-6x increased risk in COPD; low-dose CT screening for heavy smokers (≥30 pack-years, ≥50 years)
• Osteoporosis: screen and treat; ICS and smoking both increase fracture risk
• Depression and anxiety: highly prevalent; screen with PHQ-2 and GAD-2; treat if positive
• GERD: common; can trigger exacerbations; treat symptomatically

When to Suspect ILD: Primary Care Red Flags

• Persistent unexplained DRY COUGH — not productive, not responding to common treatments
• Progressive EXERTIONAL DYSPNOEA — insidious onset, worsening over months/years
• Fine inspiratory VELCRO-LIKE CRACKLES at lung bases — highly characteristic of fibrotic ILD
• Finger clubbing — present in ~50% of IPF cases; not seen in sarcoidosis
• 💎 Take thorough exposure history: birds, mold, feather pillows, organic dusts, silica, asbestos exposure
• Systemic features (joint pain, rash, Raynaud's, myalgia) suggest connective tissue disease-associated ILD

ILD: Initial Investigations & Referral

• Chest X-ray: reticular/nodular opacities, lower zone predominance; can be NORMAL in early disease
• Spirometry: restrictive pattern (reduced FVC, normal or elevated FEV₁/FVC; reduced TLC on plethysmography)
• Reduced DLCO (diffusing capacity): sensitive early indicator of gas exchange impairment
• Blood tests: FBC, ESR, CRP, ANA, anti-dsDNA, anti-Scl70, anti-Ro/La, RF — screen for connective tissue disease
• 🚨 REFER to respiratory specialist for HRCT chest + MDT discussion — do NOT delay referral
• 💎 Do NOT start empirical immunosuppression in primary care — accurate diagnosis essential before treatment

ILD: Management Principles

• Gold standard: MDT evaluation (pulmonologist, radiologist, pathologist) — improves diagnostic accuracy
• Anti-fibrotics (IPF): Pirfenidone or Nintedanib — slows FVC decline by ~50%; does not reverse fibrosis
• Immunosuppression (connective tissue disease-ILD, HP): corticosteroids ± steroid-sparing agents
• Remove exposure: critical for hypersensitivity pneumonitis — identify and eliminate causative antigen
• Non-pharmacological: Pulmonary rehabilitation; supplemental oxygen for hypoxaemia; handheld fan for breathlessness
• 💎 Advance care planning: integrate palliative care early; IPF is progressive and often fatal