EFFECT OF JAW POSITION AND POSTURE ON FORCED INSPIRATORY AIR-FLOW IN NORMAL SUBJECTS AND PATIENTS WITH OBSTRUCTIVE SLEEP-APNEA

Objective: This study evaluated whether substantial airflow changes oc cur by changing both body posture and jaw position in normal subjects and patients with obstructive sleep apnea (OSA). Design: A case-contro l design was utilized to assess group differences (OSA vs control) and each subject served as his/her own control subject to assess conditio n differences (jaw position and body posture changes). Subjects includ ed 16 male patients with OSA (aged 33 to 71 years) whose conditions we re diagnosed at the UCLA Sleep Disorders Laboratory with a polysomnogr aphic recording, and 9 male non-OSA subjects (aged 22 to 52 years). Th e experimental intervention in the study involved alterations in body posture and jaw positioning. Airflow changes were determined using a s pirometer that assessed the velocity of airflow during a forced inspir ation. Subjects in this study all had the middle portion (25 to 75%) o f their maximum forced inspiratory flow (FIF25-75) curve measured in t hree positions: (1) normal jaw position-upright body posture (N-U); (2 ) normal jaw position-supine body posture (N-S); and (3) protrusive ja n position-supine body posture (P-S). Setting: The study was conducted at the UCLA Dental Clinical Research Center. Results: Both groups had a significant decrease in their FIF25-75 upon reclining, and there we re no significant group differences regarding the magnitude of this ch ange. Both groups also had a nearly full recovery of their FIF25-75 ai rflow when their jaws were positioned forward while reclining. Conclus ions: These data document that when a patient is in a supine position, a 100% protrusive jaw position allows significantly more inspiratory airflow to occur.