PassFinals
Respiratory

Chronic Obstructive Pulmonary Disease

Persistent airflow obstruction caused by small-airway inflammation and emphysematous loss of elastic recoil, so the lungs cannot empty fully and gas is trapped with every breath.

In a nutshell

COPD is fixed airflow obstruction from small-airway disease and emphysema, confirmed by a post-bronchodilator FEV1/FVC below 0.7. Treat tobacco dependence, rehabilitate and vaccinate, escalate inhalers on symptoms and exacerbations, and in a flare give controlled oxygen to 88% to 92%.

Classic presentation

A 68-year-old with 40 pack-years, breathless walking up a slight hill for two years, a daily productive morning cough and three chest infections last winter.

Key points

  • Grade severity on FEV1 percent predicted: stage 1 mild 80% or above, stage 2 moderate 50% to 79%, stage 3 severe 30% to 49%, stage 4 very severe below 30%.
  • A stable resting saturation of 92% or less is the oximetry threshold that triggers arterial blood gases for long-term oxygen assessment.
  • MRC grade 3 means walking slower than contemporaries on the flat, or stopping for breath when walking at your own pace.
  • Measure serum alpha-1 antitrypsin if onset is early, the smoking history minimal or there is a family history. Refer under-40s to a specialist centre.
  • Hospital-at-home and assisted discharge are safe alternatives to admission, and every discharge after an exacerbation should use a discharge care bundle.
  • Cor pulmonale shows as ankle oedema, a raised JVP and a parasternal heave, and marks advanced disease.

First-line investigation

Post-bronchodilator spirometry: FEV1/FVC (forced expiratory volume in 1 second divided by forced vital capacity) below 0.7 in a symptomatic person over 35.

Management

Acute exacerbation: the first 15 minutes

  • ABCDE, sit upright. Oxygen by 24% Venturi mask at 2 to 4 litres/minute, target saturation 88% to 92% until the blood gas is back.3,4
  • Nebulised salbutamol 2.5 to 5 mg plus ipratropium 500 micrograms. If hypercapnic or acidotic, drive the nebuliser with compressed air and give oxygen by nasal cannulae.1,15,16
  • Prednisolone 30 mg orally once daily for 5 days. Give it to everyone admitted with an exacerbation.1,17
  • Arterial blood gas, CXR, ECG, FBC, U&E, CRP. Screen for sepsis, and look for pneumonia, pneumothorax, PE and heart failure.1,22

Acute exacerbation: after the blood gas

  • Normal PaCO2: raise the target to 94% to 98%. Raised PaCO2 with a normal pH is chronic retention: hold 88% to 92%. Repeat the gas at 30 to 60 minutes.3
  • pH below 7.35 with PaCO2 above 6.5 kPa is acidotic hypercapnic failure. Optimise medical treatment, call seniors and prepare non-invasive ventilation (NIV).5,4
  • Antibiotic only when justified. First-line oral: amoxicillin 500 mg three times daily, doxycycline 200 mg then 100 mg daily, or clarithromycin 500 mg twice daily, each 5 days.6

Acidotic hypercapnic failure: non-invasive ventilation

  • Start NIV within 60 minutes of the blood gas that prompted it, and within 120 minutes of hospital arrival, in a designated NIV area.21,1
  • A BTS-hosted trust example starts IPAP at 10 to 15 cmH2O and EPAP at 4 cmH2O, then titrates and repeats gases at 1 and 4 hours. Use the approved local NIV chart.23
  • Keep saturations 88% to 92% on NIV, and agree a ceiling of care before starting. Consider intubation if pH stays below 7.15 or acidosis worsens.5,1

Stable COPD: what every patient gets

  • Treat tobacco dependence: combination nicotine replacement therapy, varenicline, cytisinicline or bupropion, plus behavioural support. Nothing else slows decline as much.7,1,2
  • Annual influenza vaccine plus a single dose of pneumococcal vaccine (PPV23 or PCV20). No booster is needed for this risk group.1,8
  • Refer for pulmonary rehabilitation at MRC dyspnoea grade 3 or above, and after any admission for an exacerbation.1,4
  • Short-acting bronchodilator as needed: salbutamol 100 to 200 micrograms inhaled, or ipratropium. Check technique at every change and at least annually.1,9,4
  • Written self-management and exacerbation action plan. Give a rescue pack of prednisolone and antibiotics only to those who will use and report it correctly.1

Stable COPD: escalate, then review

  • No asthmatic features: long-acting muscarinic antagonist (LAMA) plus long-acting beta-2 agonist (LABA). Asthmatic or steroid-responsive features: LABA plus inhaled corticosteroid (ICS).1,11,12,13
  • Triple therapy (LAMA plus LABA plus ICS) after a severe exacerbation needing admission, two moderate exacerbations in a year, or as a 3-month symptom trial.1
  • Long-term oxygen if PaO2 is below 7.3 kPa when stable, or 7.3 to 8 kPa with polycythaemia, oedema or pulmonary hypertension. At least 15 hours daily.1,4
  • Azithromycin 250 mg three times a week only on specialist advice, in a non-smoker, after sputum culture, ECG and liver function checks.1,14
  • Review at least yearly, twice yearly if very severe: symptoms, inhaler technique, smoking, exacerbations, oxygen need, BMI, mood and the action plan.1

Exam traps

  • Never diagnose COPD from smoking history or a pre-bronchodilator ratio. Older people can have a ratio below 0.7 without COPD, and young people COPD above 0.7.
  • NICE says do not use a multidimensional index such as BODE for prognosis in stable COPD, not merely that it should not be used alone.
  • Loss of hypoxic drive is not the main mechanism of oxygen-induced hypercapnia; worsened matching of blood flow to gas flow is.
  • Never withhold oxygen from a hypoxaemic patient. 88% to 92% is a starting target: if PaCO2 is normal on the gas, move to 94% to 98%.
  • Nebulise with compressed air, not oxygen, if the patient is hypercapnic or acidotic, and give the oxygen separately by nasal cannulae.
  • An inhaled corticosteroid is never used alone in COPD. It raises pneumonia risk, so record why it continues and review annually.
  • Antibiotics are not automatic in an exacerbation. NG114 requires weighing severity, admission need, previous cultures and resistance risk first.
  • Long-term oxygen is not for isolated nocturnal hypoxaemia, and is not offered to a continuing smoker, who also faces a burn risk.

Illustrations

Small-airway disease and emphysemaNormal airways and alveoli contrasted with mucus-filled small airways, thickened airway walls and emphysematous destruction of alveolar walls.PassFinals · original
Chest X-ray of hyperinflationChest radiograph showing hyperinflated lung fields, flattened diaphragms and a narrow cardiac silhouette.James Heilman, MD, Wikimedia Commons · CC-BY-SA-3.0
Spirometry and air trappingFlow-volume loop showing the concave expiratory curve of fixed airflow obstruction, with dynamic hyperinflation on exertion.PassFinals · original

Key sources

  1. NICE NG115: Chronic obstructive pulmonary disease in over 16s: diagnosis and management (NG115, published 5 December 2018, last updated 26 July 2019)Published 5 Dec 2018 | Updated 26 Jul 2019
  2. NHS: Chronic obstructive pulmonary disease (COPD) (NHS patient information on symptoms, causes, treatment and pulmonary rehabilitation, last reviewed 11 April 2023)
  3. BTS guideline for oxygen use in adults in healthcare and emergency settings (British Thoracic Society, 2017. Target saturation 88% to 92% for people at risk of hypercapnic respiratory failure; 94% to 98% otherwise)
  4. NICE QS10: Chronic obstructive pulmonary disease in adults (quality standard) (QS10, last updated September 2023. Statement 3 (oximetry 92% or less triggers blood gases), statement 4 (pulmonary rehabilitation at MRC grade 3 or above), statement 6 (emergency oxygen 88% to 92%), statement 7 (non-invasive ventilation), statement 8 (discharge care bundle))
  5. BTS/ICS guideline for the ventilatory management of acute hypercapnic respiratory failure in adults (British Thoracic Society and Intensive Care Society, Thorax 2016. Recommendation 25: start non-invasive ventilation when pH is below 7.35 and PaCO2 above 6.5 kPa despite optimal medical therapy)
  6. NICE NG114: Chronic obstructive pulmonary disease (acute exacerbation): antimicrobial prescribing (NG114, published 5 December 2018. Antibiotic choices and doses for adults aged 18 and over)Published 5 Dec 2018
  7. NICE NG209: Tobacco: preventing uptake, promoting quitting and treating dependence (NG209, published 30 November 2021, last updated 4 February 2025. Recommendation 1.12.2 lists cytisinicline, nicotine replacement therapy, varenicline and bupropion)Published 30 Nov 2021 | Updated 4 Feb 2025
  8. UKHSA Green Book chapter 25: Pneumococcal (Immunisation against infectious disease, chapter 25, version dated 2025. Single dose of PPV23 or PCV20 for adults in a clinical risk group, no booster)
  9. electronic medicines compendium: Ventolin Evohaler 100 micrograms (salbutamol) Summary of Product Characteristics (UK Summary of Product Characteristics, section 4.2: one inhalation (100 micrograms), increased to two if necessary)
  10. BNF: Salbutamol (BNF salbutamol monograph: short-acting beta-2 agonist prescribing, cautions and monitoring)
  11. BNF: Tiotropium (BNF tiotropium monograph: long-acting muscarinic antagonist prescribing and cautions)
  12. BNF: Formoterol fumarate (BNF formoterol monograph: long-acting beta-2 agonist prescribing and cautions)
  13. BNF: Budesonide (BNF budesonide monograph: inhaled corticosteroid prescribing, pneumonia risk and cautions)
  14. BNF: Azithromycin (BNF azithromycin monograph: prophylactic prescribing, QT prolongation and hepatic cautions)
  15. electronic medicines compendium: Salbutamol 2 mg/mL nebuliser solution Summary of Product Characteristics (UK Summary of Product Characteristics, section 4.2: 2.5 mg to 5 mg up to four times a day in adults)
  16. electronic medicines compendium: Atrovent UDVs 2 mL (ipratropium bromide) Summary of Product Characteristics (UK Summary of Product Characteristics, section 4.2: 500 micrograms for acute bronchospasm; 250 to 500 micrograms three to four times daily for maintenance)
  17. BNF: Prednisolone (BNF prednisolone monograph: systemic corticosteroid prescribing and withdrawal)
  18. BNF: Amoxicillin (BNF amoxicillin monograph: dosing, penicillin allergy and renal adjustment)
  19. BNF: Doxycycline (BNF doxycycline monograph: dosing, photosensitivity and pregnancy cautions)
  20. BNF: Clarithromycin (BNF clarithromycin monograph: dosing, QT prolongation and drug interactions)
  21. BTS Quality Standards for acute non-invasive ventilation in adults (British Thoracic Society, 2018. Time targets and designated clinical areas for acute non-invasive ventilation)
  22. NICE NG253: Suspected sepsis in people aged 16 or over: recognition, assessment and early management (Current adult suspected-sepsis recognition and escalation recommendations)
  23. BTS quality improvement resource: adult non-invasive ventilation algorithm (worked example protocol) (British Thoracic Society document library. Example ventilator starting pressures and blood gas timings; not a national recommendation)

This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.