The relationship between neck circumference, radiographic pharyngeal anatomy, and the obstructive sleep apneoa syndrome

We have studied the predictive Importance of neck circumference, obesity, and several radiographic pharyngeal dimensions for obstructive sleep apnoea (OSA), In 66 patients. OSA was quantified as the mean hourly number of >4% dips in arterial oxygen saturation during sleep. Neck circumference (correlation coefficient (r)=0.63, 95% confidence Interval (C.I.) 0.4~.76), obesity Index (r=0.54, 95% C.I. 0.39~.69), hyoid position (r=0.40, 95% C.I. 0.17-0.59), soft palate length (r=0.31, 95% C.I. 0.08-0.51), and hard palate-to-spine angle (r=0.29, 95% C.I. 0.0~.49), correlated significantly with saturation dips in single regression analysis. In stepwlse multiple linear regression analysis (saturation dip rate as the dependant variable), only neck size and rctroglossai space were significant independent correlates (total r =0.42, 95% C.I. 0.22-0.61, p<O.OOOl). We conclude that the relationships between general obesity, hyoid position, soft palate length, and OSA are probably secondary to variation in neck circumference. Correspondence: Dr R.J.O. Davies, The Sleep Clinic, Osier Chest Unit, Churchill Hospital, Headington, Oxford OX3 7U, UK.