Non invasive ventilation in people with cystic fibrosis

Background: Cystic fibrosis (CF) is the most common life shortening autosomal recessive inherited disease affecting Caucasian people. The two main clinical characteristics of CF are progressive pulmonary disease and pancreatic insufficiency. The goal of airway clearance technique (ACT) is to improve ventilation and mucociliary clearance. The overall purpose of this thesis was to evaluate and compare the effects of Non Invasive Ventilation (NIV) and positive expiratory pressure (PEP) on airway clearance, and to find out if the use of NIV during an exercise test would reduce carbon dioxide (CO2) retention compared to oxygen (O2) supplementation. To explore at what point after ACT spirometry should be performed, and to determine whether there are interindividual and intraindividual differences, were also studied. To describe the patients ́experiences of using NIV as an adjunct to ACT was also a purpose. Paper I, a prospective study. Twenty-four patients with CF. In adult patients, mean forced expiratory volume in one second (FEV1) improved 30 min (p=0.001), 1 h (p=0.002), and 2 h (p=0.006) after physiotherapy compared to baseline; in pediatrics it improved after the session (n.s.). There were no intraindividual variations but interindividual differences were found. Paper II, a prospective randomized study. Thirty-two patients with CF completed a 3 month long randomized trial comparing NIV with standard PEP. There was a significant reduction in lung clearance index (LCI) following NIV compared with PEP (p=0.01). Paper III, a qualitative study. Eighteen patients with CF were interviewed about their experiences using NIV during chest physiotherapy. Semi-structured interviews were conducted and analyzed using qualitative content analysis. “Becoming friends with NIV” emerged as a theme and came to represent a learning process. To facilitate this learning process, different factors should be taken into account until NIV is experienced as meningful. Paper IV, a prospective crossover study, compared O2 supplementation and NIV during an exercise test. Eight patients with CF completed an incremental test on a treadmill (using the Bruce protocol) while comparing standard treatment O2 with NIV. NIV showed a decreased rise in transcutaneous pressure of carbon dioxide (tcPCO2), maintaining the level within the normal reference values compared to O2 (p=0.01).

Conclusion: The point at which to perform a lung function test after an ACT is different for adults and children. NIV has shown to be as effective as other ACTs. Exercise tests showed tcPCO2 remaining within the normal reference values with NIV but not with PEP. All participants completed the NIV treatment without major discomfort and experienced NIV as meaningful after becoming friendly with the NIV.

List of scientific papers

I. Rodriguez Hortal, MC, Hjelte L. Time point to perform lung function tests evaluating the effects of an airway clearance therapy session in cystic fibrosis. Respir Care. 2014 Oct;59(10):1537-41.
https://doi.org/10.4187/respcare.02823

II. Rodriguez Hortal MC, Nygren Bonnier M, Hjelte L. Non invasive ventilation as airway clearance technique in cystic fibrosis. Physiother Res Int. 2016 Feb 29.
https://doi.org/10.1002/pri.1667

III. Rodriguez Hortal, MC, Hedborg, A, Biguet, G, Nygren-Bonnier, M. Experience of using non-invasive ventilation as an adjunct to airway clearance technique in adults with cystic fibrosis – a qualitative study. [Submitted]

IV. Rodriguez Hortal, MC, Hjelte, L, Nygren-Bonnier, M. Non invasive ventilation (NIV) compared to oxygen supplementation during an incremental test in adults patients with cystic fibrosis. [Manuscript]