Non-invasive ventilation is associated with long-term improvements in lung function and gas exchange in cystic fibrosis adults with hypercapnic respiratory failure

BACKGROUND

Non-invasive ventilation (NIV) is an established treatment option for cystic fibrosis (CF) patients with type 2 respiratory failure but the benefits of this therapy remain unclear. This study examined the long-term outcomes and response to NIV in a large adult CF cohort.

METHODS

All patients attending a UK adult CF Centre receiving NIV as treatment for hypercapnic respiratory failure over a nine-year period were studied prospectively. Detailed clinical data was recorded and longitudinal data measurements were examined for the three years pre and post NIV initiation to assess effect of this intervention.

RESULTS

94 patients, mean age 29.9 (SD 9.7) years, percent predicted FEV₁ 21.5 (7.3), received NIV. All patients commenced NIV in a hospital setting. 21 remain alive, 24 received double lung transplant, 49 died without lung transplantation. NIV use was associated with a stabilisation and improvement in both FEV₁ and FVC from NIV set up to three years post follow-up, in addition to an increase in body mass index and attenuation of PCO₂ (all p<0.001). No single parameter was found to predict long-term NIV response but baseline PCO₂ (p=0.005), CRP (p=0.004) and age (p=0.009) were identified as independent predictors of mortality.

CONCLUSIONS

NIV use in CF adults is associated with improvements in lung function and attenuation of hypercapnia which is maintained for up to three years post NIV initiation. Outcomes for CF patients with severe pulmonary disease commenced on NIV have significantly improved with fifty percent of patients expected to survive for approximately five years.

The effect of the weather on pulmonary exacerbations and viral infections among adults with cystic fibrosis

The effect of changes in the weather on the respiratory health of patients with cystic fibrosis (CF) is unclear. We conducted a prospective study to determine the impact of climate and season on the incidence of viral respiratory infections (VRI) and pulmonary exacerbations (PEx) among adults with CF. Between December 2010 and April 2012, 98 adults with CF were followed for 12 months. Polymerase chain reaction assays for nine viruses were performed on sputum, nose and throat swabs every 2 months and additionally at onset of PEx. Hourly temperature and relative humidity measurements were recorded throughout the study. Statistical analysis utilized generalized estimating equation (GEE) models. Pre-specified criteria for VRI and PEx were met at 29% and 37% of visits, respectively. Rhinovirus accounted for 72% of identified viruses. Incidence of rhinovirus peaked in autumn while non-rhinovirus VRI peaked in winter. Rhinovirus was associated with increased mean temperatures (OR 1.07; p = 0.001), while non-rhinovirus VRI was associated with lower mean temperatures (OR 0.87; p < 0.001). PEx occurred frequently throughout the study with no clear seasonal pattern observed. There was no significant association between climate variables and the incidence of either PEx or antibiotic prescription. There is a seasonal pattern to VRI in adults with CF. The incidence of VRI but not PEx is associated with changes in ambient temperature.

Association of airway cathepsin B and S with inflammation in cystic fibrosis

Irreversible tissue damage within the cystic fibrosis (CF) lung is mediated by proteolytic enzymes during an inflammatory response. Serine proteinases, in particular neutrophil elastase (NE), have been implicated however, members of the cysteine proteinase family may also be involved. The aim of this study was to determine cathepsin B and S levels in cystic fibrosis (CF) sputum and to assess any relationship to recognized markers of inflammation such as sputum NE, interleukin-8 (IL-8), tumor necrosis factor alpha (TNF-alpha), urine TNF receptor 1 (TNFr1), plasma IL-6, and serum C-reactive protein (CRP). Proteinase activities were measured in the sputum of 36 clinically stable CF patients using spectrophotometric and fluorogenic assays. Immunoblots were also used to confirm enzyme activity data. All other parameters were measured by ELISA. Patients had a mean age of 27.2 (8.2) years, FEV. of 1.6 (0.79) L and BMI of 20.7 (2.8). Both cathepsin B and S activities were detected in all samples, with mean concentrations of 18.0 (13.5) microg/ml and 1.6 (0.88) microg/ml, respectively and were found to correlate not only with each other but with NE, TNF-alpha and IL-8 (in all cases . < 0.05). Airway cathepsin B further correlated with circulatory IL-6 and CRP however, no relationship for either cathepsin was observed with urine TNFr1. This data indicates that cathepsin B and S may have important roles in the pathophysiology of CF lung disease and could have potential as markers of inflammation in future studies.

Inflammatory markers in cystic fibrosis patients with transmissiblePseudomonas aeruginosa

Chronic Pseudomonas aeruginosa infection in cystic fibrosis (CF) leads to a damaging host inflammatory response. There are an increasing number of reports of P. aeruginosa cross-infection at CF centres. The clinical significance of acquisition of a transmissible strain for patients who already harbour P. aeruginosa is unclear. In this study, levels of inflammatory markers in clinically stable adult CF patients who harbour transmissible and sporadic strains of P. aeruginosa have been compared. Patients with CF and chronic P. aeruginosa infection were grouped into those who harbour a transmissible P. aeruginosa and those who harbour their own sporadic strains. Total white cell and differential counts, sputum neutrophil elastase (NE), interleukin (IL)-8, tumour necrosis factor (TNF)-alpha, plasma IL-6 and NE/alpha1-antitrypsin complexes, serum C-reactive protein, and urine TNF receptor 1 were all measured in clinically stable patients 4-6 weeks following completion of intravenous antibiotic therapy. The two groups (both n=20) were well matched for per cent predicted forced expiratory volume in one second, per cent predicted forced vital capacity and body mass index. There were no significant differences in levels of white cell counts or inflammatory markers between the two groups. At times of clinical stability, cystic fibrosis patients infected with transmissible Pseudomonas aeruginosa do not have a heightened inflammatory response above that of those harbouring sporadic strains.