Cystic fibrosis (CF) is one of the most common autosomal recessive life-limiting genetic disorders in the caucasian population. NIV is a crucial management strategy of the condition but when is it most effective and when should we use it?
This study is a retrospective analysis of data captured prospectively on the electronic records at the Leeds Cystic fibrosis Centre. Data was included if the patient was 17 or older, confirmed diagnosis of CF, had recieved 12 hours or more of NIV between Jan 2008 – Dec 2018. Excluded patients included those with a transplant or with OSA. Outcomes and indication for NIV was analysed. In total n=56.
What is Non-invasive Ventilation?
In a nutshell, non-invasive ventilation (NIV) is the delivery of oxygen via a face mask and therefore eliminating the need of an endotracheal airway. NIV achieves comparative physiological benefits to conventional mechanical ventilation by reducing the work of breathing and improving gas exchange.
NIV works by creating a positive airway pressure – the pressure outside the lungs being greater than the pressure inside of the lungs. This causes air to be forced into the lungs (down the pressure gradient), lessening the respiratory effort and reducing the work of breathing. It also helps to keep the chest and lungs expanded by increasing the functional residual capacity (the amount of air remaining in the lungs after expiration) after a normal (tidal) expiration; this is the air available in the alveoli available for gaseous exchange. There are two types of NIV; non-invasive positive-pressure (NIPPV) and Negative-Pressure Ventilation (NPV).
- T2RF was the most common indication to start NIV followed by acute hypercapnic respiratory failure.
- The most common side effect of starting NIV was dizziness / light headedness and morning headaches.
- Median inspiratory pressure at start was 14cm H2O increasing to 17 while median exp pressure was 5cm H2O.
- Average oxygen requirement was 2l o2/min to maintain target saturations.
- Commercially available face masks were overwhelmingly preferred.
- ~10% of patients at the centre required NIV over 10 years.
- 4 participants had a pneumothorax.
- Adherence is ~40-50%.
The results of this retrospective analysis are in line with the UK CF registry data collected between 2007-2015. There is not currently enough data to clearly define clear criteria for initiation of treatment due to there being only small RCTs of NIV in CF exist. Current rational for the use is based on other criteria for longterm conditions such as COPD.
The majority of individuals with CF receiving NIV were on the transplant waiting list or under consideration for lung transplantation. NIV remains a successful means to bridge CF patients to lung transplantation because
its long-term use contributes to the stabilization of lung function. NIV remains the mainstay in the symptomatic care of patients receiving end-of-life treatment.
NIV is used as adjunct therapy for the management of advanced CF lung disease in a manner similar to other chronic respiratory conditions. Subjects who continued treatment with NIV showed stabilization of lung function,
despite the same frequency of exacerbations and intravenous antibiotics usage.