Si. Masumi et al., EFFECT OF JAW POSITION AND POSTURE ON FORCED INSPIRATORY AIR-FLOW IN NORMAL SUBJECTS AND PATIENTS WITH OBSTRUCTIVE SLEEP-APNEA, Chest, 109(6), 1996, pp. 1484-1489
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.