Intranasal administration of insulin on the incidence of postoperative delirium in middle-aged patients undergoing elective on-pump cardiac surgery (INIPOD-MOPS): a prospective double-blinded randomized control study protocol.

Background: Delirium, marked by acute cognitive decline, poses a life-threatening issue among older individuals, especially after cardiac surgery, with prevalence ranging from 15 to 80%. Postoperative delirium is linked to increased morbidity and mortality. Although clinical trials suggest preventability, there is limited research on intranasal insulin (INI) for cardiac surgery-related delirium. INI has shown promise in managing cognitive disorders. It rapidly elevates brain hormone levels, enhancing memory even in non-impaired individuals. While effective in preventing delirium in gastrointestinal surgery, its impact after cardiac surgery remains understudied, especially for middle-aged patients.

Method: This is a prospective randomized, double-blind, single-center controlled trial. A total of 76 eligible participants scheduled for elective on-pump cardiac surgery will be enrolled and randomly assigned in a 1:1 ratio to either receive Intranasally administered insulin (INI) or intranasally administered normal saline. The primary outcome of our study is the incidence of postoperative delirium (POD). Secondary outcomes include duration of ICU, postoperative hospital length of stay, all in-hospital mortality, the change in MMSE scores pre- and post-operation, and incidence of postoperative cognitive dysfunction at 1 month, 3 months, and 6 months after operation. Moreover, we will subjectively and objectively evaluate perioperative sleep quality to investigate the potential impact of nasal insulin on the development of delirium by influencing sleep regulation.

Discussion: Our study will aim to assess the impact of intranasal administration of insulin on the incidence of postoperative delirium in middle-aged patients undergoing on-pump elective cardiac surgery. If intranasal insulin proves to be more effective, it may be considered as a viable alternative for preventing postoperative delirium.

Trial registration: ChiCTR ChiCTR2400081444. Registered on March 1, 2024.