Determining ED90 of Flumazenil for Selective Respiratory Distress Improvement Using Remimazolam During Endoscopic Submucosal Dissection of Gastric Neoplasms: A Prospective Study.

Background: Patients undergoing endoscopic submucosal dissection under monitored anesthesia care (MAC) with remimazolam may develop respiratory distress during the procedure. In these cases, low doses of flumazenil improved respiratory distress without completely reversing sedation, which is a novel phenomenon. This study aimed to explore the ED90 of flumazenil to selectively improve respiratory distress in patients with MAC treated with remimazolam.

Methods: Flumazenil dose determination followed a biased-coin up-and-down design. Starting with a dose of 5 mcg, if respiratory distress improved, the biased-coin method was used to give the same dose in the next patient with a probability of 8/9, and a decreased dose of 5 mcg in the next patient with a probability of 1/9. Any improvement in respiratory distress within 30 s of flumazenil administration was recorded. After the procedure, patients were asked whether they had any memory recall during the procedure. Centered isotonic regression was used to determine the ED90 of flumazenil.

Results: Sixty patients were included in the study. The estimated ED90 was 76.72 mcg (95% CI: 68.07-102.62). Memory recall occurred in two of thirteen patients (15%) near the ED90 dose range (75 mcg and 80 mcg). None of the patients developed major postoperative complications (bleeding, perforation, or aspiration) within the 2-day postoperative period.

Conclusions: This study determined that the ED90 of flumazenil for effectively alleviating respiratory distress in patients undergoing MAC with remimazolam was 76.7 mcg, without reversing consciousness. These findings provide valuable guidance for the care of patients undergoing sedation.