Quantitative effects of trunk and head position on the apnea hypopnea index in obstructive sleep apnea.

STUDY OBJECTIVES

To test the hypothesis that head position, separately from trunk position, is an additionally important factor for the occurrence of apnea in obstructive sleep apnea (OSA) patients.

DESIGN

Prospective cohort study.

SETTING

St. Lucas Andreas Hospital, Amsterdam, the Netherlands.

PATIENTS AND PARTICIPANTS

Three hundred patients referred to our department because of clinically suspected OSA.

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

Patients underwent overnight polysomnography with 2 position sensors: one on the trunk, and one in the mid-forehead. Of the 300 subjects, 241 were diagnosed with OSA, based on an AHI > 5. Of these patients, 199 could be analyzed for position-dependent OSA based on head and trunk position sensors (AHI in supine position twice as high as AHI in non-supine positions): 41.2% of the cases were not position dependent, 52.3% were supine position dependent based on the trunk sensor, 6.5% were supine position dependent based on the head sensor alone. In 46.2% of the trunk supine position-dependent group, head position was of considerable influence on the AHI (AHI was > 5 higher when the head was also in supine position compared to when the head was turned to the side).

CONCLUSIONS

The results of this study confirm our hypothesis that the occurrence of OSA may also be dependent on the position of the head. Therefore in patients with a suspicion of position-dependent OSA, sleep recording with dual position sensors placed on both trunk and head should be considered.