The effects of volume versus pressure targeted non-invasive ventilation in amyotrophic lateral sclerosis

Parkes, Edward David (2025) The effects of volume versus pressure targeted non-invasive ventilation in amyotrophic lateral sclerosis. Doctoral thesis (DClinSci), Manchester Metropolitan University.

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Abstract

Introduction: Few studies have compared adherence rates between different modes of non-invasive ventilation (NIV) for the treatment of chronic respiratory failure and sleep disordered breathing in patients with amyotrophic lateral sclerosis (ALS). Quality of life (QoL) in amyotrophic lateral sclerosis (ALS) is poor and significantly worse than patients living with cancer and indeed the general population. Previous studies have compared QoL outcomes between ALS patients using NIV and those receiving standard care (no NIV). Raised apnoea hypopnoea index (AHI) and nocturnal hypoventilation contribute towards reduced health reported quality of life (HRQoL) in ALS. The use of volume targeted NIV to treat sleep disordered breathing (SDB) is limited, reflecting clinical uncertainty about its role as an effective mode of NIV in ALS patients with diaphragmatic and bulbar muscle weakness. Therefore, a prospective pilot study with randomisation was conducted to explore adherence and HRQoL difference between volume targeted auto-adjusting EPAP and pressure targeted NIV in patients diagnosed with ALS. Methods: Fifteen ALS patients were randomised to receive volume targeted auto-adjusting EPAP and pressure targeted NIV. Adherence data and HRQoL scores (revised amyotrophic lateral sclerosis functional rating score (ALSFRS-R), severe respiratory insufficiency (SRI) and modified hospital and anxiety score (mHADS)) were recorded at 14, 30, 60 and 90 days. All patients followed a standard ventilatory care pathway for ALS patients. Results: Median adherence from 0 – 90 days for volume targeted auto-adjusting EPAP NIV was 7.1 hours per day (h/d) (0.28-9.0) and 3.93 h/d for pressure targeted NIV (0-7.3). Between group comparisons of adherence by time point showed median adherence for volume targeted auto-adjusting EPAP NIV to be statistically significantly higher than pressure targeted NIV at 30, 60 and 90 days (6.29h/d (0.1-8.55) vs 2.48h/d (0-7.3); 7.54h/d (2.43-9.08) vs 5.8h/d (0-7.3) and 9.05h/d (7.8-9.5) vs 6.22h/d (0-8.66), respectively). Seventy-nine patients would be required for each NIV mode to provide appropriate statistical power for a large-scale study. ALSFRS-R and SRI scores did not statistically significantly differ between volume targeted auto-adjusting EPAP and pressure targeted NIV across time points. At 90 days ALSFRS-R and SRI were higher in patients using volume targeted auto-adjusting EPAP NIV compared to those using pressure targeted NIV (29(13.5); 22.8(12.2), p=0.4483 and n=6 52.6(15.5); 46.5(12.3), p=0.4846, respectively). mHADS was lower in the volume targeted auto-adjusting EPAP NIV group compared to pressure targeted NIV at 90 (10.8(8.1); 13.3(6), p=0.5679, respectively). Discussion: To our knowledge this is the only pilot study with randomisation comparing adherence and HRQoL between two NIV modes in ALS. Improved NIV adherence and higher ALSFRS-R, mHADS and SRI scores were observed in ALS patients using volume targeted auto-adjusting EPAP NIV compared to pressure targeted NIV. Our study provides evidence to support future clinical practice and recommends a large-scale study to fully explore the impact of volume targeted auto-adjusting EPAP NIV on adherence rates and HRQoL in ALS.