0497 Respiratory Events That Begin And End In Epochs Scored As Wake

Introduction According to the AASM Manual for the Scoring of Sleep and Associated Events (v2.5) respiratory events can be scored if the event begins or ends in an epoch of sleep. The rules do not take into account events that begin and end in epochs of wake, but span at least one epoch of sleep, or wake-sleep-wake (WSW) events. To determine the impact of these events being overlooked, further analysis was conducted. Methods 10481 previously scored studies performed at West Australian Sleep Disorders Research Institute were re-examined for the presence and frequency of WSW events. WSW events were then removed from the scored respiratory events to determine how many studies would have an altered OSA severity classification. Individual respiratory events were also examined and WSW events were compared to respiratory events scored entirely in sleep. Results Of the 10481 studies examined, 1141 (10.89%) studies were identified as having at least one WSW event. Overall, studies with severe OSA were more likely to have WSW events (26%) compared to studies with moderate (15%), mild (7%), and nil OSA (1%), and severe studies had more WSW events per hour (mean 0.72 events/hour) compared to studies with moderate (0.38 events/hour), mild (0.24 events/hour) and nil OSA (0.22 events/hour). 21 studies (0.2%) changed severity of OSA based on the addition of WSW events; 1 study (0.03%) increased from nil OSA to mild OSA; 9 studies (0.33%) increased from mild OSA to moderate OSA; 11 studies (0.47%) increased from moderate OSA to severe OSA. Overall, WSW also had longer event duration and lower oxygen desaturation that events scored entirely in sleep. Conclusion Although WSW events are only responsible for a small portion of total respiratory events, they appear to have an important clinical impact on the patient. If WSW events are scored, it may alter the diagnosis and/or treatment recommendations. Also, as WSW events are, on average, longer in duration and have a lower oxygen desaturation, these events may present a different clinical picture to the Physician. Support (If Any)