ABSTRACT
Respiratory failure may be either type 1 (oxygenation failure) or type 2 (ventilatory failure) (see Chapter 14). Ventilation is the movement of air in and out of the lungs, so with ventilatory failure there is insufficient volume moving in and out of the lungs. Because carbon dioxide clearance relies mainly on the size of breaths, ventilatory failure results in insufficient exchange of both carbon dioxide and oxygen. The British Thoracic Society (2002) defines type 2 ventilatory failure as an arterial oxygen (PaO2) below 8.0 kPa together with an arterial carbon dioxide (PaCO2) above 6.0 kPa. Severe type 2 respiratory failure may therefore need ventilatory support. Until recently, this necessitated intubation, invasive ventilation, and usually sedation and admission to intensive care; each of these creates additional risks for patients. Non-invasive ventilation (NIV) offers an easier and safer alternative for many patients with ventilatory failure. The British Thoracic Society (2002) therefore recommends that indications for NIV include:
■ COPD with a respiratory acidosis pH7.25-7.35 ■ Hypercapnic respiratory failure secondary to neuromuscular disease (e.g.
