0665 Effects of Daily Intermittent Hypercapnia on Sleep Quality in Veterans with Sleep-Disordered Breathing

Abstract Introduction Sleep-disordered breathing (SDB) is common among individuals with spinal cord injury or disease (SCI/D), contributing to impaired sleep quality and breathing instability. Traditional treatments using mechanical devices have not been well adhered to or tolerated. While novel therapeutic interventions and chemical stimulation using acute intermittent isocapnic hypoxia have been shown to enhance ventilatory plasticity, the effects of intermittent hypercapnia on sleep quality have not been investigated. This study evaluated whether daily acute intermittent hypercapnia (dAIHc) is feasible and whether it influences sleep quality and sleep-related respiratory stability in Veterans with SDB. Methods Veterans with SDB (AHI >5 events/hr), with and without SCI/D, completed a two-week dAIHc protocol. dAIHc consisted of 10 cycles of 3-minute isooxic hypercapnia (21% O₂, 5% CO₂) alternating with 5 minutes of room air, administered 5 days per week. Sleep quality was assessed before and after the intervention using the Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale (ESS), Fatigue Severity Scale (FSS), and Insomnia Severity Index (ISI). The severity for SDB was assessed before and after dAIHc using full polysomnography (using Nox A1™, including changes in total AHI, and AHI 3%). Paired t-test was sued to compare outcome measures before and after the dAIHc. Results A total of 15 Veterans with SDB completed the protocol. Participants had a mean age of 58.1 ± 11.7 years with a mean BMI of 32.5 ± 6.3, were all male, and included both SCI/D (n=9) and able-bodied (n=6) participants. Across participants who completed both baseline and post-intervention assessments, dAIHc was associated with a significant improvement with AHI 3% and ISI. Mean AHI 3% decreased from 39.0 ± 22.7 to 23.2 ± 19.7 events/hour (p = 0.01) and ISI showed a significant reduction from 11.1±7.0 to 6.3 ± 4.7 (p < 0.05). No significant change was noted in ESS, PSQI, or FSS (p=NS). Conclusion The findings show that dAIHc is a feasible intervention for Veterans with SDB, leading to significant improvements in SDB severity and insomnia symptoms. These results suggest dAIHc intervention as promising to treat SDB and improve sleep quality in this population, including those with SCI/D. Further research with larger samples is needed to confirm this. Support (if any)