Non-invasive ventilation in neuromuscular diseases: should we use higher levels of ventilatory support?

In patients with COPD, one of the leading indications for domiciliary non-invasive ventilation (NIV), a major paradigm shift has been observed over the past decade in the method for adjusting NIV settings, with the use of sufficient ventilatory support to achieve a significant reduction in PaCO₂. Whether this approach may be relevant to other populations, especially slowly progressive neuromuscular diseases (NMD), is unknown.

This study was conducted as a post hoc analysis from a previously published randomized controlled trial (NCT03458507). Patients with NMD treated with domiciliary NIV were stratified according to the level of ventilatory support: high-level tidal volume (HLV_T; mL/kg of predicted body weight [PBW]) or high-level pressure support (HLPS), defined as a value above median value of the whole population (> 6.8 mL/kg_PBW or 9.0 cmH₂O, respectively). Primary outcome was mean nocturnal transcutaneous CO₂ pressure (PtcCO₂). Secondary outcomes included adherence to NIV, leaks, and side effects.

Of a total of 26 patients, 13 were exposed to HLV_T, with significantly lower nocturnal PtcCO₂ (respectively 40.5 ± 4.2 vs. 46.3 ± 3.9 mmHg, p = 0.002). A linear correlation between V_T (mL/kg_PBW) and mean nocturnal PtcCO₂ was evidenced (r =  - 0.59, 95%CI [- 0.80; - 0.25], p = 0.002). No significant impact of HLV_T was found on secondary outcomes.

Despite the lack of power of this post hoc analysis, our results suggest that higher levels of ventilatory support are correlated with lower PtcCO₂ in patients with NMD. Further studies are desirable to assess the extent to which the level of assistance influences PaCO₂ evolution in patients with slowly progressive NMD, as well as in restrictive thoracic disorders.