Type 2 Respiratory Failure (Hypercapnic)

Type 2 respiratory failure: hypoxaemia (PaO₂ <8kPa) + hypercapnia (PaCO₂ >6kPa). Causes: COPD exacerbation, obesity hypoventilation, neuromuscular disease. In COPD: cautious O₂ to target SpO₂ 88–92% to avoid O₂-driven hypercapnia. NIV (BiPAP) is the…

NIV / Controlled Oxygen Therapy Pathway

The pathway

1 · ABG immediately

Essential to diagnose and stage. pH <7.35 with raised PaCO₂ = acute-on-chronic failure
pH <7.26 = severe — early NIV or intubation

2 · Controlled O₂

In COPD: 28% Venturi mask, target SpO₂ 88–92%
High-flow O₂ can suppress hypoxic drive and worsen hypercapnia

3 · Treat exacerbation

Salbutamol 5mg + ipratropium 500mcg nebulised (air-driven in COPD)
Prednisolone 40mg PO for 5 days
Antibiotics if purulent sputum (amoxicillin/doxycycline/clarithromycin per local policy)

4 · NIV (BiPAP) criteria

pH 7.25–7.35 with PaCO₂ >6kPa despite initial treatment
Set IPAP 10–20cmH₂O, EPAP 4–5cmH₂O
Reassess ABG in 1 hour

5 · Ceiling of care

Discuss escalation ceiling with patient before starting NIV. NIV is not a substitute for intubation if the patient is deteriorating and intubation is appropriate.

6 · Response to NIV

ABG at 1 hour: pH should be improving
If worsening — consider intubation (if appropriate) or palliative approach

7 · Escalation to ICU/intubation

pH <7.25 or worsening despite NIV
Contraindications to NIV (vomiting, reduced GCS, fixed upper airway obstruction)

Drugs

Drug	Dose	Route	Notes
Salbutamol	5mg	Nebulised (air-driven)	Do NOT use O₂-driven nebs in COPD — use air.
Ipratropium	500mcg	Nebulised (air-driven)	Combine with salbutamol.
Prednisolone	40mg	PO	5-day course. Or hydrocortisone 100mg IV if unable to swallow.
Doxycycline	200mg stat then 100mg OD	PO	If purulent sputum. Check local policy.
Amoxicillin	500mg TDS	PO	Alternative antibiotic for COPD exacerbation.

When to escalate

pH <7.25 despite 1 hour of NIV,Worsening conscious level (GCS falling),NIV not tolerated and pH deteriorating,SpO₂ <80% despite optimised O₂,Respiratory arrest — ALS/intubation

Reference: BTS NIV Guideline 2016 / GOLD COPD Guidelines 2024

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