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PRODROMAL OBESITY HYPOVENTILATION SYNDROME ‐ EARLY DETECTION OF HYPOVENTILATION IN THE VERY OBESE POPULATION

formed in a cross-sectional study of 40 patients with CF. Following clinical deterioration, 8 subjects underwent repeat studies after 1-2 years. Parameters assessed using the PSG included: sleep efficiency, arousal index (AI), respiratory disturbance index (RDI), mean nocturnal oxygen saturation (SpO2), nadir SpO2 and mean oxygen desaturation. Using the Sonomat, recorded sounds were classified as coughs or crackles based on the spectrographic variations in frequencies, intensity and timing of the sound during the respiratory cycle. Total duration (as % total sleep time) of these sounds was used to quantify recorded sounds. Results: Eight subjects (2 male; aged 29.5 5.4 years (mean SD); FEV1 of 45.0 11.9 % predicted) were studied twice. There was a statistically significant increase in mean oxygen desaturation (baseline to second study) from 1.4 1.9% to 4.0 2.1% (p=0.01). There was a trend to reduced minimum SpO2 between the baseline and second study (89.0 4.6% versus 82.8 8.9%; p=0.065). There was no statistically significant difference in any of the other PSG parameters. The Sonomat demonstrated that crackles duration increased from 21.2 15.4% at baseline to 78.6 15.5% at the second study (p=0.001). However, cough duration did not change between the two studies. Conclusions: Using the Sonomat to analyse recorded sounds, the significant increase in the presence of crackles was consistent in all subjects following clinical deterioration. As expected with deteriorating lung function, oxygen desaturation worsened over time in subjects with severe CF lung disease. However, there was no change in the other PSG markers of sleep quality despite the deterioration in lung function. We speculate that sequential use of the Sonomat to assess sleeping adventitial sounds may be useful to detect deteriorating lung function.