Systemic absorption of topical gentamicin sinus irrigation.

OBJECTIVE Evidence surrounding systemic absorption of gentamicin during intraoperative irrigation of the paranasal sinuses is lacking. The objectives of this study were to determine (1) if topical gentamicin is absorbed from the paranasal sinuses, (2) if hearing loss occurs following topical administration of gentamicin, and (3) if gentamicin placed within the sinuses travels retrograde (against mucociliary clearance) up the auditory tube to the middle ear. DESIGN Consecutive, prospective case series. SETTING Tertiary centre. METHODS A series of patients undergoing sinus surgery were identified. Fluorescein-stained gentamicin was used to irrigate the sinus cavities intraoperatively. Otoscopy using a filtered light source was performed 30 minutes postoperatively. MAIN OUTCOME MEASURES (1) Serum gentamicin levels preirrigation and at 30 minutes postirrigation and (2) change in pure-tone average and threshold at 8 kHz pre- and postoperative audiograms. RESULTS Twenty patients were enrolled. Serum gentamicin levels were detectable in three patients. Fluorescein irrigation solution was not visualized in the middle ear space. No significant hearing loss was observed in any of the patients. CONCLUSIONS Gentamicin may be absorbed from the nasal mucosa during intraoperative irrigation of the sinuses. However, detectable serum levels were well below therapeutic levels. The clinical significance of this finding requires further study to determine if topical sinus irrigation with gentamicin is a safe procedure.