Impact of maxillo-mandibular advancement on quality of life in OSAS patients F. Laganà 1 , D. Rossi 2 , G. Beltramini 2 , M. Romano 2 , A. Russillo 2 , A. Giannì 2 1 Maxillofacial Surgery Ospedale San Martino Genova, Italy 2 Maxillofacial Surgery and Odontostomatology Policlinico Di Milano Fondazione Ca’ Granda Università Degli Studi Di Milano, Italy Introduction: The aim of this study is to investigate the impact of maxillo-mandibular advancement on quality of life in OSAS patients that underwent surgery between 2005 and 2012. Materials and methods: Eleven OSAS patients that underwent surgery participated in the study. Data collection consisted of self-administered questionnaires in- corporating Epworth sleepiness scale, The MOS 36-Item Short Form Health Survey (SF-36 Quality of life questionnaire), Short Form Oral Health Impact Profile (OHIP-14) and Calgary Sleep Apnea Quality of Life Index (SAQLI). Results: The ESS have found improvements in all patients treated (before ESS: 10.5; post surgery ESS 4.09); the OHIP is the question- naire which recorded the lowest number of improvements (average pre surgery OHIP: 15.64; average post surgery OHIP 19.36); the SF- 36 gave overall good results. Conclusion: The study that we have performed has shown us how that this syndrome affects the life of the patients, allowing to em- phasize that maxilla-mandibular advancement can undoubtedly improve the quality of life in all its aspects. http://dx.doi.org/10.1016/j.sleep.2015.02.502 Phenotyping obstructive sleep apnea M. Ruthranesan, A. Am Institute of Respiratory Medicine, Malaysia Introduction: Ventilatory instability plays a role in the patho- physiology of obstructive sleep apnea. Ventilatory instability tends to occur when there is a high ventilatory drive. The concept of loop gain has been used to explain ventilatory instability. Materials and methods: To highlight the importance of recognising phenotypes of Obstructive sleep apnea patients who would benefit from combination therapy with continuous positive airway pres- sure (CPAP) and acetazolamide. Case study of a patient who was treated with combination therapy. Results: A 30 years old intern presented with a history of excessive daytime sleepiness, witnessed apnea and unrefreshed sleep. He had a body mass index of 33 kg/m 2 and a neck circum- ference of 42 cm. His Epworth Sleepiness scale (ESS) recorded 17/24. His arterial blood gases were normal. He was not on any other medications. He underwent a full overnight polysomnograph which showed severe obstructive sleep apnea with apnea– hypopnea index of 65.7/h with central apnea index of 21.2/h and obstructive index of 43.8/h. His central apneas occurred predomi- nantly in the NREM stage His MRI brain, spirometry and echocardiogram were normal. He was subsequently put on (CPAP) but the apneic events persisted. We subsequently prescribed him with acetazolamide 250 mg 1 hour before sleep and then was put on Continuous Positive Airway Pressure which showed a reduc- tion in apnea index, total duration of apnea and improvement in his daytime sleepiness as assessed by ESS. Conclusion: It is important to recognise phenotypes of obstruc- tive sleep apnea with a high loop gain mechanism as a combination of medications and CPAP achieves a better outcome. http://dx.doi.org/10.1016/j.sleep.2015.02.503 Prevalence of excessive sleepiness and insomnia in relation to severity of obstructive sleep apnea I. Saxvig 1 , S. Lehmann 2 , S. Gulati 2 , H. Aurlien 2 , S. Pallesen 3 , B. Bjorvatn 1 1 Center for Sleep Medicine and Norwegian Competence Center for Sleep Disorders, Haukeland University Hospital, Norway 2 Center for Sleep Medicine, Haukeland University Hospital, Norway 3 Department of Psychosocial Science, University of Bergen and Norwegian Competence Center for Sleep Disorders, Haukeland University Hospital, Norway Introduction: Obstructive sleep apnea (OSA) may often co- occur with other sleep-related symptoms. Whereas an association with excessive sleepiness has been widely recognized, a possible association with insomnia has received less focus. The aim of the study was to investigate the prevalence of insomnia and excessive sleepiness in relation to OSA severity. Materials and methods: The sample comprised 1115 patients re- ferred to a university hospital on suspicion of OSA. Mean age was 48.4 ± 13.4 years and 70.8% were male. OSA was diagnosed based on polygraphic sleep studies and classified according to the apnea– hypopnea index (AHI) as no OSA (AHI < 5), mild OSA (AHI 5–14.9), moderate OSA (AHI 15–29.9) or severe OSA (AHI ≥ 30). Excessive sleepiness was measured using Epworth Sleepiness Scale (ESS), a score ≥11 indicating excessive sleepiness. Insomnia was mea- sured using the Bergen Insomnia Scale (BIS), which allows identification of insomnia according to both the old (DSM-IV, ICSD- 2) and the new (DSM-V, ICSD-3) diagnostic criteria. Both questionnaires are validated in Norwegian. Data were explored using Pearson chi-square as well as bivariate logistic regression analy- ses with OSA severity (0 = AHI < 15, 1 = AHI ≥ 15) as the dependent variable. Results: Among the patients referred to the hospital on suspi- cion of OSA, no OSA was found in 40.6% of the patients, whereas 29.8% had mild, 16.2% had moderate, and 13.4% had severe OSA, yielding a prevalence rate of OSA of 59.4%. The prevalence of ex- cessive sleepiness increased steadily from 40.5% in the no-OSA group to 46.5% in the mild-OSA group, 52.0% in the moderate-OSA group and 58.0% among patients with severe OSA (p = 0.001). Insomnia on the other hand did not increase in prevalence depending on OSA severity. Using the old criteria, insomnia was found in 78.8% in the no-OSA group, 79.3% in the mild-OSA group, 74.3% in the moderate- OSA group and 76.3% in the severe-OSA group (p = 0.56) whereas, using the new diagnostic criteria, insomnia was found in 52.2% in the no-OSA group, 54.9% in the mild-OSA group, 48.5% in the moderate-OSA group, 44.6% in the severe-OSA group (p = 0.13). The logistic regression analyses showed that excessive sleepiness was positively associated with OSA severity with odds ratio 1.60 in the crude analyses (95% CI 1.23–2.08). Insomnia based on the new cri- teria was negatively associated with OSA severity with odds ratio 0.73 (95% CI 0.56–0.96). Conclusion: Both excessive sleepiness and insomnia were prev- alent in the OSA patients. The prevalence of excessive sleepiness increased with increasing OSA severity. The opposite trend was found for insomnia according to the new diagnostic criteria, S193 Abstracts/Sleep Medicine 16 (2015) S2–S199