Inter-Night Variability of Nocturnal Pulse Oximetry in People Living With Motor Neuron Disease: A Retrospective Observational Study.

Background and objective: Nocturnal pulse oximetry (NPO) is a simple and inexpensive assessment tool that has previously been shown to correlate with prognosis and timing of non-invasive ventilation (NIV) initiation in people living with motor neuron disease (plwMND). However, the optimal number of nights for measuring NPO has not been defined for this population, with other respiratory conditions exhibiting both low and high night-to-night variability in NPO parameters. This study aims to determine the inter-night variability in NPO data over three nights in plwMND.

Methods: We conducted a retrospective analysis of 132 studies in which plwMND underwent three consecutive nights of NPO. Intraclass correlation coefficients (ICC) were used to assess the reliability of key NPO parameters, including mean percentage of total recording time with oxygen saturation (SpO₂) < 90% (T90), oxygen desaturation index (ODI), basal SpO₂ and nadir SpO₂. The proportion of plwMND meeting NIV criteria based on single-night versus multi-night assessments was also compared.

Results: Excellent reliability was observed for T90 (ICC(1) = 0.940) and ODI (ICC(1) = 0.901), while basal SpO₂ (ICC(1) = 0.845) and nadir SpO₂ (ICC(1) = 0.768) demonstrated good reliability. However, relying on a single-night NPO assessment failed to identify 12% of plwMND who met NIV criteria when evaluated over three nights.

Conclusion: Despite good to excellent inter-night variability of NPO data in plwMND, multi-night NPO monitoring improves the accuracy of identifying plwMND requiring NIV. These findings support the need for multi-night assessments to enhance clinical decision-making in MND management.