Analysis of inspiratory flow shapes in patients with partial upper-airway obstruction during sleep.

STUDY

OBJECTIVE

To study the spectrum of inspiratory flow signal shapes in patients with partial upper airway obstruction during sleep.

DESIGN

We identified seven different inspiratory flow shapes and determined their frequencies in two groups of patients (10 postmenopausal women and 19 men after surgical treatment for sleep apnea) and in 9 control subjects.

SETTING

Sleep research unit, Department of Physiology, University of Turku, Finland.

MEASUREMENTS AND

RESULTS

Nasal flow was recorded with nasal prongs. The shape analyses were performed with an automated attribute grammar recognizer. The inspiratory flow-shape distributions differed significantly between patients and control subjects. The flow shapes were also different between postmenopausal women and men after uvulopalatopharyngoplasty.

CONCLUSIONS

The differences in the inspiratory flow-shape distributions between the control subjects and the two patient groups suggest that the upper airways behave differently in the three study groups. Automated inspiratory flow-shape analysis seems to be a promising tool to distinguish patient groups with different upper airway function to be treated with different treatment alternatives. The physiologic correlates of each flow-shape class remain to be elucidated.