Am. J. Respir. Crit. Care Med., Vol 152, No. 1, 07 1995, 179-185.
Effects of body position on the upper airway of patients with obstructive sleep apnea
DA Pevernagie, AW Stanson, PF Sheedy 2nd, BK Daniels and JW Shepard Jr
Sleep Disorders Center, Mayo Clinic, Rochester, Minnesota 55905, USA.
Fast-CT scanning was used to study the effects of changes in body position
on upper airway (UA) size and shape in 11 awake subjects with obstructive
sleep apnea (OSA). Six patients with position (P)-dependent OSA were
compared with five patients with nonposition (NP)-dependent OSA. Scans were
repeated in the prone (PRN), right side (RS), and supine (SUP) body
positions at both functional residual capacity and end-inspiratory tidal
volume. Significant group, group by position, and borderline group by
respiration effects were detected for minimum but not mean UA dimension
data. Significant differences between groups were noted in minimum
cross-sectional area and minimum lateral distance but not in minimum
anteroposterior distance in the RS and SUP positions. Turning from the PRN
to the RS or SUP position tended to decrease UA size in the NP group by
decreasing the lateral distance, while the opposite effect was found in the
P group. The results indicate that changes in body position during
wakefulness affect the lateral but not the anteroposterior dimensions of
the UA, and the UA behaves differently in patients with NP and P OSA in
response to changes in body position.
