To the Editor.
—In their article on the pathophysiology of upper airway closure during sleep, Drs Kuna and Sant'Ambrogio1 seem uncertain about the importance of increased nasal resistance in obstructive sleep apnea (OSA). On page 1388, paragraph 1, they comment that"... correction of these nasal problems does not usually resolve OSA" and "Nevertheless, reduction in upstream resistance by treatment of nasal problems is indicated in OSA subjects." The importance of increased nasal resistance in sleep apnea is unclear.We have measured nasal resistance by anterior rhinomanometry (right nasal resistance, left nasal resistance, and calculated combined nasal resistance), in 141 consecutive patients undergoing polysomnography for symptoms suggestive of OSA. There was no significant difference in combined nasal resistance between patients with OSA (apnea/hypopnea index, >15; mean, 46; n = 71) and snorers (apnea/hypopnea index, <15; mean, 5; n=70). Only six patients had a raised combined nasal resistance (>3 cm H2