Table 3 Studies reporting other outcomes

Penzel et al. [39] (2001) Germany

16 male adult patients with suspected obstructive sleep apnea (OSA)

Observational sleep study reporting upper airway closing pressure in lateral and supine position during three sleep stages.

Airway closing pressure (P_crit, cmH₂O)

+

P for all < 0.05.

• Light sleep:

Airway closing pressure is a measure of collapsibility, lower/negative pressure means less collapsibility.

Lateral: −2.2, supine: 0.6

• Slow-wave sleep:

Lateral: −1.7, supine: 0.3

• REM-sleep:

Lateral: −2.2, supine: 1.2

Isono et al. [40] (2002) Japan

8 male patients with OSA under evaluation for surgery

Observational study with patients anesthetized and airway closing pressure measured in lateral and supine positions at two areas (retropalatal and retroglossal airway). Airway pressure (P_AW, cmH₂O) was measured to cessation of air passage. This P_AW equals the airway closing pressure, P_crit.

Airway closing pressure (P_crit, cmH₂O)

+

For both areas: p < 0.05.

• Retropalatal airway:

Airway closing pressure is a measure of collapsibility, lower/negative pressure means less collapsibility.

Lateral: −1.86, supine: 2.05

• Retroglossal

• airway:

Lateral: −3.17, supine: 0.49

Jordan et al. [38] (2003) Australia

33 healthy, nonsmoking adult volunteers

Polysomnographic study (PSG) study reporting baseline inspiratory minute ventilation (MV) and upper airway resistance (R_ua) in left lateral and supine position.

• MV_insp, mean (l/min):

?

+

MV: Small differences, may not be clinically important.

Men: Lateral: 7.5, supine: 7.0

Women: Lateral: 5.9, supine: 6.0

• R_ua, mean (cmH₂O/l)

R_ua: Higher airway resistance in supine position. Reports “significantly difference”, no p-value.

Men: Lateral: 4.1, supine: 5.8

Women: Lateral: 3.4, supine: 6.6

Arai et al. [36] (2004) Japan

30 children (1–10 years) with OSA, scheduled for ear-nose-throat (ENT) surgery.

Observational study of airway obstruction in general anesthesia, in lateral and supine position, using stridor score (1: normal, 4: no airway sound detected)

Stridor score, median:

+

p < 0.05

Lateral: 3, supine: 4

Crude but clinically important outcome.

Litman et al. [41] (2005) USA

17 children (2–11 years), scheduled for MRI.

Observational study of total upper airway volume in left lateral and supine position, using MRI.

V_{upper airway}, mean (ml):

+

p < 0.001

Left lateral: 8.7, supine: 6.0

Considerable reduction of the upper airway volume in the supine position compared to the lateral.

Arai et al. [37] (2005) Japan

18 children (1–11 years) with OSA, scheduled for ENT surgery.

Observational study of airway obstruction in general anesthesia, in lateral and supine position, using stridor score.

Stridor score, median:

+

p < 0.05

Lateral: 3, supine: 4

Supine position reduced the airway obstruction. (Addition of jaw thrust and/or chin lift reduced the obstruction further.)