Non-invasive ventilation for the treatment of hypercapnic respiratory failure in cystic fibrosis

Median survival for patients with cystic fibrosis (CF) has improved steadily over the past several decades as a result of a multifaceted treatment approach to the disease.1 Despite this aggressive care, many patients with classic disease eventually develop respiratory failure from progressive airways obstruction and bronchiectasis.2 At this stage, treatment strategies may focus on alleviating both the symptomatic and physiological effects of respiratory failure. Initially respiratory failure may be mainly hypoxic (type 1: arterial oxygen pressure (Pao₂) <8 kPa (or 60 mm Hg), with normal arterial carbon dioxide pressure (Paco₂)), and supplemental oxygen during sleep and/or exercise may be effective. However, when the disease becomes more severe, hypercapnia may ensue (type 2: Paco₂ >6 kPa (or 45 mm Hg)). Such patients with chronic respiratory failure usually have obvious clinical signs and symptoms, and blood gas analysis demonstrates a compensated respiratory acidosis.3 Thus it is important to periodically measure arterial blood gases in all patients with severe CF lung disease, to monitor for this serious complication of the disease.

When CF patients develop chronic respiratory failure, symptoms include the usual clinical sequelae of hypoxia and hypercapnia, as well as worsening dyspnoea associated with the increased work of breathing, sleep fragmentation and daytime fatigue, and reduced activities of daily living. Hypoxia with hypercapnia, and an elevation in serum bicarbonate, can support the need for adjunctive treatments. If oxygen treatment alone is judged insufficient, non-invasive ventilation (NIV) may be considered.3 Patients with CF may suffer acute respiratory failure during an exacerbation of moderate to severe disease, or indeed without any identified specific acute insult. A 2002 British Thoracic Society Standards of Care document listed the criteria for the use of NIV in acute respiratory failure.3 Of note, this document states that NIV …