EFFECT OF CHRONIC CONTINUOUS POSITIVE AIRWAY PRESSURE (CPAP) THERAPY ON UPPER AIRWAY SIZE IN PATIENTS WITH SLEEP-APNEA HYPOPNEA SYNDROME

Background - There is evidence to suggest that chronic continuous posi tive airway pressure (CPAP) therapy may produce reversible changes in upper airway morphology and function in patients with sleep apnoea/hyp opnoea. This study was designed to examine the effect of chronic CPAP therapy on upper airway calibre.Methods - Twenty four men with the sle ep apnoea/hypopnoea syndrome (mean (SE) apnoea/hypopnoea index 37 (5)) underwent lateral cephalometry with measurement of posterior airway s pace performed before and at least three months after initiation of CP AP therapy. Results - There was no weight change between the two asses sments and mean CPAP use was 4.8 (0.4) hours per night. Posterior airw ay space (PAS) was measured in erect and supine postures. PAS supine i ncreased with CPAP therapy from a mean (SE) of 11.8 (0.8)mm to 13.4 (0 .8)mm, but PAS erect did not. Correlation of the change in PAS (dPAS) before and after CPAP therapy showed an increase with increasing CPAP compliance measured as machine run time both for dPAS supine (r = 0.68 ) and dPAS erect (r = 0.47). Conclusions - Patients with the sleep apn oea/hypopnoea syndrome regularly using CPAP for more than four hours p er night all showed an increase in dPAS supine. The use of chronic CPA P increases PAS supine probably by a reduction in upper airway oedema, and the change in size is dependent on CPAP use.