Abstract
The permeability and resistance of the maxillary ostium was investigated in 44 maxillary sinuses in 23 patients with acute rhinitis which had been present for 1–10 days. Only 8 of the sinuses had a patent ostium: 16 had an obstruction which was overcome during blowing or sniffing, and the rest were obstructed during blowing and sniffing. Ostial obstruction showed a positive correlation to pathological roentgeno-graphy of the sinus, but the former was somewhat more common. It seems therefore probable that acute sinusitis usually starts with an ostial obstruction. Antral irrigation yielded a small quantity of mucus from 6 of the sinuses, but otherwise nothing. The median ostial resistance was only slightly below that in acute sinusitis.