S76 The clinical impact of 3D printed positive airway pressure (PAP) therapy interfaces (3DPiPPIn): a randomised controlled trial

<h3>Introduction and objectives</h3> The recognised treatment for sleep disordered breathing is PAP therapy. Three-dimensional printing of customised interfaces could improve comfort and clinical outcomes. The primary aim was to assess the impact of customised versus conventional interfaces on Apnoea Hypopnea Index (AHI) at 6 months. Secondary outcome measures were: interface leak (L/min), PAP therapy concordance (%), prevalence of pressure ulcers and Epworth Sleepiness Score (ESS). <h3>Methods</h3> A Randomised Controlled Trial (RCT) with 160 adults naïve to PAP therapy and diagnosed with SDB (AHI ≥15 events/hr). Randomisation was stratified by age and ethnicity. Structured light facial scans (POP2, Revopoint, China) were post-processed to engineer a 3D printed mould (Fuse 30+, Formlabs, USA). The mould was injected with silicone to produce a customised PAP oronasal interface cushion. Demographics are reported using descriptive statistics. AHI was compared using quantile regression, adjusting for baseline age, ethnicity and AHI. Quantile regression was used to account for the skewed distribution of the AHI data, providing a more robust analysis than mean-based methods. Secondary outcomes were compared using logistic (pressure ulcer), quantile (interface leak, concordance) and linear regressions (ESS). <h3>Results</h3> The intervention and control groups were similar at baseline (table 1.). 56 control and 42 intervention participants completed the trial (p=0.007). The intervention was associated with a higher number of events/hr (difference in medians = 1.5, 95% CI: 0.65 to 3.12, p=0.059) a higher interface leak (difference in medians 30.0L/min, 95% CI 7.36 to 40.14, p &lt;0.0001), and lower compliance (%) (difference in compliance = 0.78, 95% CI 0.05 to 1.54, p =0.04) at six months. There was a non-significant 87% higher chance of developing a pressure ulcer compared to the control group (OR = 1.87, 95% CI: 0.39 to 10.1, p = 0.434). There was no difference in ESS between the control and intervention groups at six months (difference between control and intervention = 0.361, 95% CI -1.61 to 2.33, p = 0.72). <h3>Conclusions</h3> Customised oronasal interfaces in their current format were not superior to conventional interfaces. Improvements in the design and manufacturing workflow are required before theoretical benefits of customised interfaces can be realised.