Protruding the tongue improves posterior rhinomanometry in obstructive sleep apnoea syndrome

In posterior rhinomanometry (PRM), oropharyngeal pressure is measured using a tube placed between the tongue and the hard palate. For valid results th e patient must position the tongue and soft palate so that bath the orophar ynx and nasopharynx remain open. A high rate of failure of conventional PRM has been reported in normal individuals. In patients with obstructive slee p apnoea syndrome (OSAS), upper airway abnormalities may further increase t he failure rate. This study proposes a modification of the technique in which protrusion of the tongue enhances pressure transmission between the nasopharynx and the m outh. In eight normal subjects, resistance was similar when measured by both meth ods. Of 24 OSAS patients, conventional PRM was unsuccessful in 11. In the r emaining 13 patients, a significant correlation between the two methods was found, but resistance was lower by "tongue-out" than by conventional PRM, consistent with a decrease, during tongue protrusion, in retropalatal resis tance, which is a component of the "nasal" resistance measured by PRM. In 2 6 OSAS patients, unilateral nasal resistance values measured by "tongue-out " PRM were similar to those measured by anterior rhinomanometry. When the " tongue-out" method was used routinely in 541 snorers, failure rates were 1. 1% in the 272 non-OSAS patients and 3.7% in the 269 OSAS patients. These results indicate that posterior rhinomanometry with tongue protrusion is a highly effective tool for measuring nasal resistance in snorers.