LAUSR

Background Obstructive sleep apnoea syndrome (OSAS) is characterised by repeated apnoea’s due to partial or total collapse of the upper airway during sleep, resulting in fragmentation of sleep and intrusive daytime somnolence. Intermittent hypoxia in untreated OSAS leads to oxidative stress and airways inflammation in central and peripheral airways. Continuous positive airway pressure ventilation (CPAP) maintains upper airway patency preventing apnoea’s. Impulse oscillometry measures lung function and respiratory impedance, including large (R20) and small airways resistance(R5-R20). We used impulse oscillometry to monitor change in pulmonary mechanics in response to long term CPAP therapy in OSAS. Methods 18 patients with confirmed OSAS had impulse oscillometry readings at baseline and after three months of CPAP therapy. Results Patient feedback on oscillometry measurements in monitoring therapy is reassuring. A significant decrease in R5-R20 was observed in those adherent to CPAP (p= 0.0547). Reactance measured by X5 and Ax decreased with CPAP adherence, p=0.0547 and p<0.05,respectively. A decrease in Epworth Sleepiness Score was observed in all patients (p<0.05). 9 out of 18 patients were adherent to CPAP therapy, with usage greater than 4 hours for 70% of days or more. Total airways resistance (R5) decreased in those adherent to CPAP therapy and increased in non-adherence. Conclusion It is feasible to use of Impulse oscillometry to monitor physiology in OSAS. CPAP therapy improves symptom burden. Our results suggest effective CPAP therapy is associated with a reduction in small airways resistence and reactance. This data provides mechanistic insights into the aggravation of asthma and COPD when there is an overlap with OSAS. This justifies further exploration of impulse oscillometry as a bio-marker in disease monitoring in OSAS and other chronic lung disease.Abstract P132 Table 1 Baseline 3 months R5 R5–20 R20 Ax X5 R5 (%change) R5–20 (%change) R20 (%change) Ax (%change) X5 (%change) 1 5.18 1.03 4.15 25.88 0.19 2 6.46 0.14 6.32 1.69 0.65 7.81(+20.9) -0.23 8.04 (+27.2) 1.17(-30.8) -0.35 (-154) 3 5.05 1.15 3.9 21 0.32 4.49(-11.1) 0.58(-49.6) 3.91 (+0.3) 11.76(-44) -0.29 (-191) 4 8.26 2.17 6.09 17.64 1.22 6.33(-23.4) 1.05(-51.6) 5.28 (-13.3) 12.62(-28.5) -0.15 (-113) 5 7.25 2.93 4.32 48.71 0.99 6.54(-9.8) 2.45(-16.4) 4.09 (-5.3) 25.04(-48.6) -0.84 (-185) 6 5.22 0.34 4.88 6.67 -0.97 3.96(-24.1) 0.09(-73.5) 3.87 (-20.7) 2.87(-57) -0.63 (+35.1) 7 3.75 0.05 3.7 8.82 -0.35 3.81(+1.6) 0.44(780) 3.37 (-8.9) 6.6(-25.2) -1.05 (-200) 8 5.04 0.93 4.11 15.94 -1.78 3.92(-22.2) 0.7(-24.7) 3.22 (-21.7) 14.04(-11.9) -1.16 (-34.8) 9 6.19 1.26 4.93 17.5 -0.24 4.12(-33.4) 0.69(-45.2) 3.43 (-30.4) 8.78(-49.8) -1.2 (-400) 10 6.15 2.33 3.82 32.06 2.59 11 4.24 1.59 2.65 24.38 0.79 12 6.44 1.13 5.31 26.94 0.67 13 4.22 1.01 3.21 18.8 0.36 4.02(-4.8) 0.52(-48.5) 3.5 (+9) 7.71(-59) -0.084 (+76.7) 14 3.17 0.57 2.6 2.69 -0.01 3.47(+9.5) 0.6(+5.3) 2.89 (+11.2) 4.73(+75.8) -0.49 (-4800) 15 4.5 0.28 4.22 9.04 -0.38 6.21(+38) 1(+257) 5.21 (+23.4) 20.68(+128) -0.84 (-121) 16 6.39 2.73 3.66 24.68 0.21 6.86(+6.9) 3.23(+18.3) 3.63 (-0.8) 34.14(+38.3) 3.09(+1571) 17 4.8 0.89 3.91 11.93 -0.23 18 3.33 -0.73 4.06 6.76 1.33