[Effects of dexmedetomidine doses on postoperative cognitive dysfunction and serum β- amyloid and cytokine levels in elderly patients after spine surgery: a randomized controlled trial]

Effects of dexmedetomidine on early postoperative cognitive function and postoperative inflammatory response: a systematic review and network meta-analysis

Background

Dexmedetomidine (DEX) has demonstrated potential as an effective agent for enhancing early postoperative cognitive function. However, there is ongoing debate regarding its optimal dosage and impact on early postoperative inflammatory response. This study aimed to assess and prioritize the effects of varying doses of DEX on early postoperative cognitive function and inflammatory response, in order to identify the most effective intervention dosage.

Methods

Randomised controlled trials (RCTs) and retrospective cohort studies (RCS) from PubMed, Embase, and Cochrane Library up to January 28, 2024, were included. The Mini-Mental State Examination (MMSE) was utilized to assess the impact of varying doses of DEX on cognitive function during the early postoperative period as the primary outcome, peripheral blood levels of IL-6 and TNF-α were considered as secondary outcomes. Meta-analysis and Bayesian Network Meta-Analysis (NMA) were conducted using R. Funnel plots were generated using Stata 15.0.

Results

A total of 29 studies involving 2,807 patients and 25 different doses of DEX were included. DEX was given at a loading dose of 0.3-1.0 μg/kg followed by a maintenance dose of 0.1-0.5 μg/kg/h, or at a uniform intraoperative dose of 0.4-0.7 μg/kg/h. Network meta-analysis revealed most doses of DEX were significantly more effective than normal saline (NS) in improving postoperative MMSE scores (on days 1, 3, and 7) and lowering IL-6 and TNF-α levels. Probability results showed that a 1 μg/kg loading dose followed by a 0.6 μg/kg/h maintenance dose was the best dosing regimen for improving MMSE scores on postoperative days 1 (97.3%), 3 (100%), and 7 (99.9%), as well as for reducing postoperative blood IL-6 levels (1.3%). On the other hand, 0.3 μg/kg followed by 0.2 μg/kg/h was the optimal dosing regimen for reducing postoperative blood TNF-α levels (6.6%).

Conclusion

Compared with NS, intraoperative intravenous DEX improved early postoperative cognitive function and postoperative inflammatory response in patients undergoing elective surgery. In particular, a 1 μg/kg loading dose and a 0.6 μg/kg/h maintenance dose resulted in the best improvement in postoperative MMSE scores and blood IL-6 levels, while a 0.3 μg/kg loading dose followed by a 0.2 μg/kg/h maintenance dose is the optimal regimen for lowering postoperative blood TNF-α levels.Systematic review registration: https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=433932, identifier CRD42023433932.

Magnetic Resonance Imaging Characteristic Evaluation of Dexmedetomidine on Neurocognitive Dysfunction in Elderly Patients with Colorectal Tumors after Laparoscopic Operation

In order to investigate the effects of Dexmedetomidine (DEX) on postoperative anesthesia recovery time and consciousness function in elderly patients with laparoscopic colorectal tumors, 40 patients (20 in the control group and 20 in the DEX group) were selected. The DEX group was intravenously pumped at a rate of 0.8 μg/kg/h for 10 min and then continuously pumped at a rate of 0.3 μg/kg/h until 40 min before the end of the operation. The two groups were given the same amount of normal saline, with the same way of anesthesia. The results showed that the visual analog scale (VAS) score of pain in the two groups decreased signally. Compared with the control group, the inflammatory factors tumor necrosis factor (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), and macrophage inflammatory protein (MIP-2) in the DEX group were remarkably decreased at T1 and T2 stages, with a considerable difference (P < 0.05). One month after the auxiliary diagnosis of colorectal tumor, no clear nodular, irregular shape patches, or patchy diffuse limited points were found, which indicated that the whole tumor had been removed. In summary, DEX could improve postoperative cognitive function in elderly patients who underwent the laparoscopic radical resection of colon cancer, and its mechanism was related to the reduction of inflammatory factors. Therefore, the anesthesia intervention with DEX during the operation had a positive significance for tumor resection.

Progress in the correlation of postoperative cognitive dysfunction and Alzheimer's disease and the potential therapeutic drug exploration

Postoperative cognitive dysfunction (POCD) is a decrease in mental capacity that can occur days to weeks after a medical procedure and may become permanent and rarely lasts for a longer period of time. With the continuous development of research, various viewpoints in academic circles have undergone subtle changes, and the role of anesthesia depth and anesthesia type seems to be gradually weakened; Alzheimer's disease (AD) is a latent and progressive neurodegenerative disease in the elderly. The protein hypothesis and the synaptic hypothesis are well-known reasons. These changes will also lead to the occurrence of an inflammatory cascade. The exact etiology and pathogenesis need to be studied. The reasonable biological mechanism affecting brain protein deposition, neuroinflammation, and acetylcholine-like effect has a certain relationship between AD and POCD. Whereas there is still further uncertainty about the mechanism and treatment, and it is elusive whether POCD is a link in the continuous progress of AD or a separate entity, which has doubts about the diagnosis and treatment of the disease. Therefore, this review is based on the current common clinical characteristics of AD and POCD, and pathophysiological research, to search for their common points and explore the direction and new strategies for future treatment.