The controlled oxygen therapy in AECOPD is the most critical initial intervention distinction from asthma — in COPD, a subgroup of patients (the hypercapnic COPD patient, often GOLD stage 3-4) have hypoxic ventilatory drive as their primary respiratory stimulus because chronic hypercapnia has reset their central chemoreceptor threshold, making CO₂ no longer the dominant ventilatory drive. Administering high-flow oxygen to these patients removes the hypoxic drive, reduces respiratory effort, allows CO₂ to accumulate further, and can cause CO₂ narcosis and respiratory arrest. The target SpO₂ in AECOPD is 88-92% — deliberately lower than the 94-98% target for most other acute medical conditions. The correct oxygen delivery device: Venturi mask at 24% or 28% provides a precise inspired oxygen concentration regardless of the patient's breathing pattern (unlike simple face masks or nasal cannulae). In practice: all COPD patients being transported to hospital by ambulance should have a Venturi mask with written instructions on the target SpO₂ — this information should be on the GP referral letter and should be communicated verbally to the paramedic crew.

The COPD rescue pack (self-management emergency supply) is one of the most evidence-based and cost-effective interventions in COPD management — the rescue pack contains a short course of prednisolone 30 mg OD x 5 days and an antibiotic (amoxicillin 500 mg TDS x 5 days, or doxycycline 200/100 mg x 5 days as alternative). It is supplied in advance to patients with COPD who have had two or more exacerbations per year, with a written self-management plan specifying exactly when to start: increased breathlessness beyond baseline + change in sputum colour or quantity, lasting more than 24-48 hours without other explanation. RCTs show rescue packs reduce emergency department attendance by approximately 40% and unplanned hospital admission by approximately 30%. The GP's role: ensure rescue packs are prescribed for all eligible patients at COPD annual review, provide clear written instructions, and document rescue pack use at each review. A rescue pack used more than 3 times per year should trigger specialist review.

The ABG interpretation in AECOPD follows a systematic pattern — type 2 respiratory failure (hypercapnic failure) shows: pH low (<7.35 = acidosis), pCO₂ high (>6 kPa = hypercapnia), pO₂ low (<8 kPa = hypoxaemia), and bicarbonate elevated (compensatory metabolic alkalosis — reflecting chronic CO₂ retention). The pH is the most clinically critical value: pH 7.25-7.35 = moderate acidosis — NIV indicated; pH <7.25 = severe acidosis — NIV may fail, consider intubation. The bicarbonate level distinguishes acute from chronic: a high bicarbonate (>28 mmol/L) with high pCO₂ indicates that the kidneys have had time to compensate = chronic hypercapnia (the patient's baseline). An acutely elevated pCO₂ with normal or only mildly elevated bicarbonate indicates acute decompensation superimposed on the chronic baseline. This distinction matters because: a patient with chronic pCO₂ of 7 kPa + bicarbonate of 34 mmol/L + pH 7.36 is compensated and may be at their baseline; the same patient with pH 7.28 is acutely decompensated and needs NIV.

Azithromycin prophylaxis for frequent exacerbators is a NICE-recommended evidence-based intervention (NICE NG115) that significantly reduces exacerbation frequency but requires careful safety monitoring — the ALBERT trial (NEJM 2011) demonstrated that azithromycin 250 mg taken daily for 12 months reduced AECOPD frequency by approximately 27% vs placebo in selected patients (non-smoking, GOLD 2-4, ≥1 exacerbation requiring medical intervention in the prior year). The NICE recommendation is for 3x/week dosing to reduce macrolide resistance induction. The essential safety checks before prescribing: (1) ECG — baseline QTc must be normal (<450 ms in men, <470 ms in women); azithromycin prolongs the QT interval and can cause torsades de pointes in susceptible patients; (2) NTM (non-tuberculous mycobacteria) testing — azithromycin monotherapy can promote azithromycin-resistant NTM if NTM lung disease is present; (3) hearing test at 6 months — macrolides can cause sensorineural hearing loss at long-term doses. Annual review of indication and safety monitoring is required.

Long-term oxygen therapy (LTOT) is the only pharmacological intervention in COPD that has been shown to improve survival — the MRC and NOTT trials (1981) demonstrated that LTOT ≥15 hours/day in COPD patients with resting hypoxaemia (PaO₂ ≤7.3 kPa or 55 mmHg, SpO₂ ≤88%) reduced 3-year mortality from approximately 67% to approximately 45%. LTOT assessment must be performed when the patient is stable (at least 5 weeks after any exacerbation) because transient hypoxaemia during an exacerbation does not qualify for LTOT. The assessment: ABG at rest during two stable measurements ≥3 weeks apart. Indications: PaO₂ ≤7.3 kPa on air at rest (stable) = LTOT; PaO₂ 7.3-8 kPa + pulmonary hypertension/cor pulmonale/polycythaemia/nocturnal hypoxaemia = LTOT. Prescribe: concentrator supplying ≥15 hours/day, targeting PaO₂ ≥8 kPa without CO₂ rise. Smoking on LTOT = risk of facial burns — GPs must document and address smoking status at every LTOT review.

The 5-day prednisolone course for AECOPD is a paradigm shift from the historical 14-day course — the REDUCE trial (JAMA 2013) was a landmark multi-centre RCT in Switzerland that compared prednisolone 40 mg OD for 5 days versus 14 days in AECOPD. The primary outcome (time to next exacerbation over 180 days) was equivalent between groups, with the 5-day group having significantly lower cumulative corticosteroid exposure. NICE NG115 subsequently updated the UK recommendation to 5 days at 30 mg. The practical clinical implication: prescribing 10 x 5 mg prednisolone tablets per exacerbation rather than 28 tablets. GPs who continue to prescribe 14-day prednisolone courses for AECOPD are exposing patients to unnecessary corticosteroid burden (adrenal suppression, diabetes destabilisation, bone loss, skin fragility) without additional therapeutic benefit.

Pulmonary rehabilitation (PR) post-hospitalisation is one of the most effective and most underutilised interventions in COPD management — the evidence is striking: a Cochrane review (McCarthy et al., 2015) of PR started within 4 weeks of hospitalisation for AECOPD showed that early PR reduced re-hospitalisation by approximately 50% (NNT 4) and reduced all-cause mortality by approximately 40% at 12 months. Despite this evidence, only approximately 5-10% of COPD patients who are admitted to hospital receive PR referral before discharge, and adherence to NHS PR programmes is approximately 50% in routine practice. The barriers: waiting times (3-6 months in many areas), lack of awareness among clinicians, and patient reluctance (breathlessness during exercise is frightening). GPs should pro-actively refer to PR at every COPD review for eligible patients (MRC ≥3) and should specifically refer at the post-hospitalisation review.

The ReSPECT (Recommended Summary Plan for Emergency Care and Treatment) form in severe COPD serves a critical function in preventing unwanted aggressive acute medical intervention at the end of life — a patient with GOLD 4 COPD who is admitted to hospital in a severe AECOPD may, without a documented plan, be intubated in an ITU despite having clearly expressed preferences for non-escalation of treatment to medical professionals in the past. The ReSPECT form documents: patient's priorities and preferences, the clinical recommendation for CPR (do not attempt CPR = DNACPR), and the recommended ceiling of medical treatment (e.g., 'NIV if appropriate but no intubation'). It should be completed in advance, when the patient is clinically stable and cognitively able to participate, reviewed annually, and a copy kept with the patient at home and on the electronic record. GPs who do not initiate ACP and ReSPECT planning for patients with FEV1 <30% or who have been intubated during a previous AECOPD are missing a critical clinical and ethical responsibility.

The COPD annual review is a QOF-incentivised structured review that forms the backbone of community COPD management — QOF indicators COPD001-012 cover: spirometry confirmation, symptom assessment (MRC), inhaler technique, medication review, smoking, BMI, vaccination, and exacerbation frequency. Practices that do not code exacerbation events correctly in the clinical record fail to identify frequent exacerbators (who need treatment escalation) and underperform on QOF. The CAT score (COPD Assessment Test — a patient-completed 8-item questionnaire available free at catestonline.org) provides a comprehensive QoL assessment in 2 minutes and is now the preferred assessment tool in GOLD guidelines over MRC alone because it captures the full impact of COPD on daily life, not just breathlessness.