Therapy

• tachypnoea: rate 23 per minute or more
• pH 7.25 to 7.35 with pCO₂ > 6 kPa

Why?

• Non-invasive positive pressure ventilation reduces need for endotracheal intubation and death ^{a b} and helps reduce days on mechanical ventilation if used as an adjunct to weaning (on average 6 days) ^a
• However complications are common. These include facial skin abrasions or necrosis (2.1% to 21%), pneumonia (0.6% to 5.5%), retention of secretions (0% to 17%), conjunctivitis (0% to 14%), and gastric distention (0% to 3%). ^a
• Facial masks are better tolerated than nasal masks. They cause more facial necrosis and gastric distention, but less conjunctivitis than nasal masks. ^a
• Ventillatory support and aggressive care is poorly cost-effective for high-risk patients (> 50% chance of dying within 2 months)  with acute respiratory failure. ^a

Non-invasive ventilation reduces intubation and death in severe cases

Patient	Treatment	Comparison	Outcome	CER	RRR (95% CI)	NNT (95% CI)
acute exacerbation of COPD b	non-invasive ventilation	no ventilation	required endotracheal intubation	74%	65% (40% to 80%)	2 (1 to 3)
			death at weeks	26%	67% (7% to 89%)	5 (3 to 32)
COPD on mechanical ventilation a	non-invasive ventilation weaning	standard weaning	failure to wean	52%	69% (19% to 88%)	3 (2 to 9)