Different btn wind in high pressure zone and low pressure zone

Posted on Jun 18, 2026 in Medicine

1. ASTHMA

Diagnosis (Adults)

  • First-line tests:
    • Blood eosinophils OR FeNO
  • Diagnostic thresholds:
    • FeNO ≥ 50 ppb OR raised eosinophils → asthma diagnosed
  • If unclear:
    • Bronchodilator reversibility (BDR)
      • ↑ FEV1 ≥ 12%
  • If still unclear:
    • PEF variability (2 weeks)
  • If still suspected but tests negative:
    • Bronchial challenge test (specialist)

Severity (Acute Asthma)

  • Severe:
    • PEFR 33–50%
    • RR > 25
    • Pulse > 110
    • Unable to complete sentences
  • Life-threatening:
    • PEFR < 33%
    • Confusion
    • Exhaustion
    • Cyanosis
    • Silent chest
    • Normal or raised PaCO₂ (≥ 6 kPa = near-fatal)

⚠️ Important:

  • Normal PaCO₂ = impending respiratory fatigue (life-threatening)


Acute Management

  • O₂ target: 94–98%
  • Nebulised salbutamol (oxygen-driven)
  • Nebulised ipratropium
  • Oral prednisolone (first-line)
  • ABG if SpO₂ < 92%

If deterioration:

  • Acidosis → intubate & ventilate
  • Do NOT use CPAP/BiPAP

Discharge Criteria

  • Stable 12–24h on discharge meds
  • No oxygen/nebulisers
  • PEF > 75% best/predicted

Treatment Pathway (NICE)

  • PRN ICS/formoterol (AIR)
  • Low-dose MART
  • Moderate-dose MART
  • Add-on: LAMA or LTRA
  • Specialist referral if uncontrolled

When to refer

  • Poor control on moderate-dose MART + add-ons
  • High eosinophils or FeNO despite treatment
  • Frequent exacerbations


Key practical points

  • Rinse mouth after ICS → prevent oral candidiasis
  • Inhaler technique: hold breath 10 sec, wait 30 sec between puffs
  • Severe asthma → pregnant patients always admit

2. COPD

Diagnosis

  • Post-bronchodilator spirometry:
    • ↓ FEV1/FVC ratio

First-line treatment

  • SABA or SAMA

Escalation

  • If breathless:
    • No asthma features → LABA + LAMA
    • Asthma/steroid–
      Responsive features:
      • LABA + ICS

Asthma/steroid-responsive features:

  • Atopy or previous asthma
  • Eosinophilia
  • FEV1 variability > 400 mL
  • PEF variability > 20%


Exacerbation

  • Antibiotics ONLY if:
    • Purulent sputum OR pneumonia

Antibiotics:

  • Amoxicillin
  • Doxycycline
  • Clarithromycin

Steroids:

  • Prednisolone 5 days

NIV indication

  • pH < 7.35 AND PaCO₂ > 6 kPa despite treatment

LTOT

  • PaO₂ < 7.3 kPa on 2 occasions
  • Do NOT give if actively smoking

Complications

  • Polycythaemia
  • Chronic CO₂ retention (respiratory acidosis)
  • ↑ pneumonia risk (ICS)
  • Common organism: Haemophilus influenzae

COPD prophylaxis

  • Azithromycin (selected patients only)
  • Baseline: ECG + LFTs


3. BRONCHIECTASIS

Features

  • Chronic productive cough
  • Recurrent infections
  • Haemoptysis
  • Clubbing

Diagnosis

  • HRCT (gold standard)

Common organism

  • Haemophilus influenzae

Management

  • Postural drainage
  • Airway clearance physiotherapy
  • Inspiratory muscle training
  • Surgery if localised disease
  • Transplant if advanced disease

4. ALPHA-1 ANTITRYPSIN DEFICIENCY

  • Young patient (30–40)
  • Emphysema + abnormal LFTs
  • Lower lobe emphysema (unlike smoking COPD = upper lobes)
  • Obstructive spirometry
  • ↑ risk of hepatocellular carcinoma
  • Can be diagnosed prenatally


5. INTERSTITIAL LUNG DISEASE (ILD)

IPF

  • Older patient
  • Progressive dyspnoea + dry cough
  • Clubbing
  • Fine end-inspiratory crackles

Tests:

  • HRCT = gold standard

Spirometry:

  • Restrictive:
    • ↓ FVC
    • ↑ FEV1/FVC
    • ↓ TLCO

Treatment:

  • Pirfenidone

Extrinsic Allergic Alveolitis

  • Avoid trigger (main treatment)

Sarcoidosis

Features:

  • Bilateral hilar lymphadenopathy
  • Hypercalcaemia
  • Erythema nodosum
  • Lupus pernio
  • Parotid enlargement


Steroid indications:

  • Hypercalcaemia
  • Uveitis
  • Pulmonary disease
  • Neuro/cardiac disease

⚠️ Most cases resolve spontaneously

6. VASCULITIS

Granulomatosis with Polyangiitis (GPA)

  • ENT + lungs + kidneys
  • cANCA positive

Microscopic Polyangiitis

  • pANCA
  • Renal involvement

EGPA (Churg-Strauss)

  • Asthma
  • Eosinophilia
  • pANCA

7. PNEUMONIA

CAP

  • CRB65 = 0 → outpatient
  • First-line: Amoxicillin
  • Repeat CXR at 6 weeks


HAP

  • ≥48h after admission

Treatment:

  • Non-severe: Co-amoxiclav
  • Severe: Piperacillin-tazobactam OR 3rd gen cephalosporin

Organisms:

  • Staph aureus
  • Pseudomonas

Key complications

  • Lung abscess
  • Empyema

8. LUNG ABSCESS

  • Foul-smelling sputum
  • Night sweats
  • Air-fluid level on CXR
  • Usually aspiration
  • Polymicrobial

Treatment:

  • Prolonged IV antibiotics
  • Drain if not improving


9. PLEURAL DISEASE

Exudate (Light’s criteria)

  • Protein ratio > 0.5 OR
  • LDH > 2/3 upper limit

Causes:

  • Malignancy
  • Pneumonia
  • TB
  • CTD (e.G. SLE)

Empyema:

  • pH < 7.2
  • Low glucose
  • High LDH
    → needs drainage + antibiotics

10. PNEUMOTHORAX

Tension pneumothorax

  • Hypotension
  • Tracheal deviation
  • Absent breath sounds
  • Shock

⚠️ Treat immediately → needle decompression (NO imaging)


High-risk features (need chest drain)

  • Haemodynamic compromise
  • Hypoxia
  • Bilateral PTX
  • Underlying lung disease

  • 50 + smoker

  • Haemothorax

Management principles

  • Small/minimally symptomatic → conservative
  • Needle aspiration first-line (if symptomatic)
  • Chest drain if failure/high risk
  • Persistent leak → VATS referral
  • Re-expansion pulmonary oedema if too rapid drainage

11. ARDS

Criteria:

  • Acute illness
  • Bilateral infiltrates
  • No cardiac cause
  • P/F ratio < 300 mmHg (~40 kPa)

Causes:

  • Sepsis
  • Pancreatitis
  • Trauma


Management:

  • Prone ventilation

12. SLEEP APNOEA

  • Features:
    • Daytime sleepiness
    • Hypertension
  • Diagnosis:
    • Polysomnography
  • Treatment:
    • Weight loss
    • CPAP

13. LUNG CANCER (HIGH YIELD)

Small cell

  • SIADH
  • ACTH → Cushing’s
  • Lambert-Eaton

Squamous

  • PTHrP → hypercalcaemia
  • Cavitation
  • HPOA

Adenocarcinoma

  • Most common in non-smokers


Pancoast

  • Hoarseness (RLN palsy)

Referral

  • ≥40 + haemoptysis → 2-week wait

Surgery contraindications

  • Malignant pleural effusion
  • SVC obstruction
  • Vocal cord paralysis
  • FEV1 < 1.5 L

14. OCCUPATIONAL / ENVIRONMENTAL

Asbestosis

  • Lower zone fibrosis
  • ↑ lung cancer risk (esp smokers)

Silicosis

  • Upper zone fibrosis
  • Eggshell calcification

Coal workers

  • Upper zone fibrosis

Occupational asthma

  • Isocyanates (commonest)


5. SPIROMETRY PATTERNS

Obstructive

  • Asthma
  • COPD
  • Bronchiectasis
  • A1AT deficiency
    → ↓ FEV1/FVC

Restrictive

  • IPF
  • Asbestosis
  • Sarcoidosis
  • Obesity
  • Neuromuscular disease
  • Kyphoscoliosis
    → ↓ FVC, normal/high FEV1/FVC

TLCO

  • ↓ Emphysema, fibrosis
  • Normal/high asthma