Many patients with cystic fibrosis (CF) require hospitalization and/or Intensive Care Unit (ICU) admission because of acute exacerbation of chronic respiratory failure or for any acute deterioration of clinical status. Non-invasive ventilation (NIV) is the first option for the clinical management of CF patients with moderate-to-severe respiratory distress and NIV has been shown to improve gas exchange, reduce respiratory muscle work and improve pulmonary function in patients with obstructive lung disease in general and those with acute CF exacerbation. High-flow nasal oxygen cannula (HFN) is a relatively new system providing heated and humidified, high-flow (50L/min) oxygen through the nostrils. This device provides a small positive pressure, probably washes-out the pharyngeal dead space, reduces inspiratory resistance, and possibly facilitates secretion clearance. The technique is very well tolerated. From a physiologic standpoint, this device could help CF patients by improving gas exchange, reducing respiratory workload, and facilitating mucus clearance. Non-interrupted delivery may be possible given better clinical tolerance in contrast with bi-level positive pressure NIV. Whether the short-term physiological efficacy of HFN is comparable to NIV is unknown and there is no study on the benefit of HFN in CF patients.

The aim of this study is to compare the physiological effects of HFN and NIV in CF patients requiring ventilatory support. Our hypothesis is that HFN will not be inferior to NIV, as evaluated by breathing pattern, gas exchange, and respiratory workload and will decrease dead space. In addition, comfort and preference between the two techniques will be evaluated.

Inclusion criteria:

• Age ≥ 18 years

• Cystic fibrosis as defined by clinical features in conjunction with 2 CF causing mutations and/or 2 sweat tests with sweat chloride > 60 mmol/l

• Clinical indication for NIV based on at least one of the following criteria:

  • Signs of clinical respiratory distress - RR > 24/min, accessory muscle use, or increased dyspnea
  • Progressive increase in arterial PCO2
  • Nocturnal hypoventilation treated by NIV but requiring daytime NIV because of clinical worsening

Exclusion criteria:

• Active massive hemoptysis
• Pneumothorax with pleural drainage and persistent air leak
• Hemodynamic instability requiring vasopressors
• Uncooperative
• Recent upper airway or esophageal surgery
• Patients with skin or chest wall or abdominal trauma