P034 Noxturnal cRIP: An alternative to AASM recommended flow sensors in analysis of respiratory events in polysomnography

Abstract Introduction AASM recommends the use of nasal pressure (NP), oronasal thermal flow (Th), and respiratory inductance plethysmography (RIP) for detecting and characterising respiratory events (RE) in polysomnography. A previous comparative study assessed utility of Noxturnal RIP flow (cRIPflow) as an alternative to Th for identification of RE in polysomnography. This demonstrated that cRIPflow was comparable with AASM recommendation for Th and NP (TH-NP) and indicated higher accuracy than Th in RE identification. We further investigate utility of cRIPflow between varying groups of apnoea hypopnoea index (AHI) severity. Method Respiratory scoring was performed by an experienced scorer on 10 diagnostic studies under AASM standards. Scoring was repeated using three different measurements for each study: cRIPflow only, Th only and Th-NP. AHI, central apnoea index (CAI), obstructive apnoea index (OAI), mixed apnoea index (MAI) and hypopnoea index (HI) were calculated. Data was catagorised into Group1 (AHI <30/hr) and Group2 (AHI >30/hr). Wilcoxon matched pairs test was utilised for comparison between flow measurements. Results Statistical difference found in Group1 (n=6) HI comparing cRIPflow vsTh (cRIPflow 6.08/hr+/-5.87SD, Th 4.57/hr+/-4.27SD, p=0.0312). No other statistical differences in RE identified when comparing cRIPflow vsTh, cRIPflow vs Th-NP and Th vs Th-NP within Group1 (n=6) and Group2 (n=4). Discussion This data suggests cRIPflow may be more sensitive in HI identification in lower severity AHI populations. Analysis with larger sample size would provide more insight. cRIPflow is comparative with AASM recommended flow sensors across varying AHI severity populations, suggesting an alternative method for detecting and characterising RE in polysomnography.