Average volume-assured pressure support (AVAPS) is a novel way to deliver NIV. In this mode, a target tidal volume is set, and the device adjusts the pressure support to reach that volume. A particular potential benefit is that it may adapt to disease progression, as in patients with progressive Motor Neurone Disease. NICE guidance (2010) recommend follow up every 3 months. We propose to investigate if this new technology improves safety during the initial period of ventilator support.

Aim

1. To identify the trend in pressure support and hours of use of AVAPS ventilation in patients with ventilatory failure due to MND.

2. Look at compliance and tolerability on patients with AVAPS.

Methods Retrospective review of case notes and downloads from the ventilators of 6 patients identified to have started on AVAPS due to ventilatory failure secondary to MND. Average AHI, IPAP, EPAP, hours of use, compliance during first three months were reviewed.

Results There was no significant change in IPAP (Mean 14.78 at 1 month, 14.98 at 3 months) or EPAP (5.91 at 1 month, 6.57 at 3 months). Average use (6 hrs 44 min at one month rising to 8 hrs 48 min at three months) and compliance (percent greater than 4 h 77.6% at 1 month to 89.5% at 3 months) did show positive trends but did not reach significance.

Conclusions This study shows an increase in average hours of use and compliance in the first 3 months of use. Tidal volumes and pressure support remain preserved. This initial data would suggest no benefit in providing the more expensive AVAPS machine compared to standard BiPAP S/T mode. Larger prospective studies looking at disease progression and ventilation usage in MND are warranted.