Effect of Gelfoam in the Middle Ear on In Vitro/Vivo Model

Abstract

Objective: 1) Determine the dissolution pattern of Gelfoam and Invotec with saline and low grade boric acid solution. 2) Measure the effect of both gelatins in animal model hearing in postoperative time. 3) Understand the direct effect of boric acid treated gel in the middle and inner ear.

Methods: In vitro, 1 cm² of Gelfoam and Invotec colored with Congo Red and immersed in saline solution 0.9% and boric acid pH 6.3. Pixel density analysis was performed to determine degradation. Thirty live Sprague-Dawley rats, females of 100 g, were anesthetized with ketamine/xilacine, divided into 5 groups. Preoperatory and postoperatory ABRs were measured. All bullas were processed for histopathology.

Results: Invotec dispersion and degradation was 25% sooner than Gelfoam. Boric acid treating resulted in rapid degradation of both gelatins by 18%. Hearing recovery by the Gelfoam group occurred in days 5 and 6, and Invotec treated between days 4 and 5. A shorter period of time of 4 to 5 days in boric acid treated Gelfoam. Boric acid treated Invotec results in 4 days. Mild histological inflammatory reaction was seen in all groups.

Conclusion: Gelfoam and Invotec show important differences that could impact short term hearing result showing a shorter reabsorption period of the Invotec. Boric acid impacted significantly gelfoam reabsorption with less impact on Invotec. No major histological changes found. Boric acid reduces absorption time of the cheaper Gelfoam.