Efficacy of a reverse-phase polymer as a submucosal injection solution for EMR: a comparative study (with video)

IntroductionReverse-phase polymers undergo a temperature-dependent liquid-to-gel transition that may provide a more durable cushion for EMR and could yield improvements in safety and efficacy.ObjectiveOur purpose was to assess the efficacy of poloxamer solution PS137-25 as a submucosal injection.DesignComparative study among 3 different solutions for EMR using ex vivo and in vivo porcine models.InterventionsA total of 120 gastric submucosal cushions were performed in fresh ex vivo porcine stomachs with saline solution 0.9% (n = 40), hydroxypropyl methylcellulose (HPMC) (n = 40), and PS137-25 (n = 40). Five in vivo porcine colon EMRs were then performed.Main Outcome MeasurementsHeight and duration of submucosal cushions were measured in the ex vivo model, and the usefulness of reverse-phase polymers was assessed by in vivo en bloc resection.ResultsEx vivo: The height of mucosal elevation was greater with PS137-25 (10.3 ± 2.2 mm) than with saline solution (8.3 ± 2.6 mm) or HPMC (9.05 ± 2.3 mm, not significant). All submucosal elevations with PS137-25 lasted longer (more than 20 minutes) than with saline solution (20.9 ± 11 minutes, P < .01) or HPMC (89 ± 32 minutes, P < .01). After 120 minutes, the elevations obtained with PS137-25 showed no differences in size, shape, or consistency from initial measurements. In vivo: All 5 EMRs were successfully performed after 1 injection of PS137-25. No repeat injections were needed. During resection, a large gel cushion was noted.ConclusionsMucosal elevation with PS137-25 is more durable than with other substances, with no changes in size or consistency observed over 120 minutes. Additionally, reverse-phase polymers performed well in in vivo colon EMRs. These results suggest that reverse-phase polymers may provide increased safety and efficacy for EMR procedures.