The Effects of Dexmedetomidine on Perioperative Neurocognitive Outcomes After Noncardiac Surgery: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Effects of dexmedetomidine on postoperative pain and early cognitive impairment in older male patients undergoing laparoscopic cholecystectomy

The primary aim of the present study was to investigate the effect of dexmedetomidine (DEX) on postoperative pain and early cognitive impairment in old male patients, who underwent laparoscopic cholecystectomy (LC). A total of 97 old patients, subjected to LC at the 980 Hospital of the Joint Service Support Force of the People's Liberation Army of China, were randomly divided into two groups, namely the DEX and normal saline groups. Patients in the DEX group received an intravenous infusion of 0.8 µg/kg DEX within 10 min following general anesthesia, followed by a maintenance infusion of 0.5 µg/(kg/h). Furthermore, patients in the normal saline group were treated with an equivalent volume of normal saline. Cognitive function was assessed using the Mini-Mental State Examination (MMSE) and the Montreal Cognitive Assessment (MoCA) tests at 6 h, 1, 2 and 3 days, postoperatively. The incidence of postoperative cognitive dysfunction (POCD) and postoperative adverse events were recorded for both groups. In addition, the Visual Analogue Scale (VAS) pain score was utilized to assess the pain level of all patients, while the Quality of Recovery-15 (QoR-15) scale was employed to analyze the postoperative recovery results. Therefore, the MoCA score was higher in the DEX group compared with the normal saline group at 6 h and day 1 postoperatively. Additionally, the MMSE score was higher at 6 h postoperatively in the DEX group compared with the normal saline group. Correspondingly, the incidence of POCD was lower in the DEX group compared with the normal saline group at 6 h and day 1, after LC (P<0.05). VAS score in resting state for patients in the DEX group was significantly lower compared with the normal-saline group (P<0.05). Furthermore, the QoR-15 scale score in patients in the DEX group was notably increased compared with the normal saline group on the first and second days after the operation (P<0.05). Overall, the present study verified that the continuous infusion of DEX at a rate of 0.5 µg/(kg/h) during LC could effectively reduce the incidence of early POCD and alleviate postoperative pain in old male patients, thus facilitating postoperative recovery.

Transcranial ultrasound neuromodulation facilitates isoflurane-induced general anesthesia recovery and improves cognition in mice

Delayed arousal and cognitive dysfunction are common, especially in older patients after general anesthesia (GA). Elevating central nervous system serotonin (5-HT) levels can promote recovery from GA and increase synaptic plasticity to improve cognition. Ultrasound neuromodulation has become a noninvasive physical intervention therapy with high spatial resolution and penetration depth, which can modulate neuronal excitability to treat psychiatric and neurodegenerative diseases. This study aims to use ultrasound to noninvasively modulate the brain 5-HT levels of mice to promote recovery from GA and improve cognition in mice. The dorsal raphe nucleus (DRN) of mice during GA was stimulated by the 1.1 MHz ultrasound with a negative pressure of 356 kPa, and the liquid chromatography coupled tandem mass spectrometry (LC-MS/MS) method was used to measure the DRN 5-HT concentrations. The mice's recovery time from GA was assessed, and the cognition was evaluated through spontaneous alternation Y-maze and novel object recognition (NOR) tests. After ultrasound stimulation, the mice's DRN 5-HT levels were significantly increased (control: 554.0 ± 103.2 ng/g, anesthesia + US: 664.2 ± 84.1 ng/g, *p = 0.0389); the GA recovery time (return of the righting reflex (RORR) emergence latency time) of mice was significantly reduced (anesthesia: 331.6 ± 70 s, anesthesia + US: 223.2 ± 67.7 s, *p = 0.0215); the spontaneous rotation behavior score of mice was significantly increased (anesthesia: 59.46 ± 5.26 %, anesthesia + US: 68.55 ± 5.24 %; *p = 0.0126); the recognition index was significantly increased (anesthesia: 55.02 ± 6.23 %, anesthesia + US: 78.52 ± 12.21 %; ***p = 0.0009). This study indicates that ultrasound stimulation of DRN increases serotonin levels, accelerates recovery from anesthesia, and improves cognition, which could be an important strategy for treating delayed arousal, postoperative delirium, or even lasting cognitive dysfunction after GA.

Effects of dexmedetomidine dosage on the short-term cognitive function of elderly patients undergoing cardiac surgery

BACKGROUND

This study aimed to investigate the effects of perioperative dexmedetomidine (DEX) infusion rates on the postoperative short-term cognitive function.

METHODS

A total of 88 patients aged ≥ 60 years who underwent cardiac surgery from January 2022 to November 2022 at the First Affiliated Hospital of The University of Science and Technology of China (USTC) were included. Based on a single-center pilot analysis, patients were divided into two groups according to the rate of intraoperative DEX infusion, which started after tracheal intubation and continued until 1 h before extubation in the cardiac surgery intensive care unit. In Group L (n = 44), the infusion rate was 0.1-0.5 µg/kg/h (low-dose group), whereas in Group H (n = 44), the infusion rate was 0.5-0.9 µg/kg/h (high-dose group). Clinical outcomes were then compared between the groups. The Mini-Mental State Evaluation (abbreviated as MMSE1, MMSE2, MMSE3, and MMSE4) scale was used for the assessment of cognitive function, which was conducted on postoperative Days 2 (T1), 7 (T2), 14 (T3), and 28 (T4), with the score from postoperative Day 2 (MMSE1) considered as the primary observation.

RESULTS

Patients in Group L had higher MMSE1 scores compared to those in Group H (26.0 [24.0, 27.0] vs. 24.5 [22.0, 26.0], p = 0.046), and there was no significant difference in the scores between the groups at all subsequent time points. Group H exhibited a higher incidence of hypotension and bradycardia compared to Group L (p = 0.044 and p = 0.047, respectively).

CONCLUSIONS

Compared to a high dose (0.5-0.9 µg/kg/h) of DEX infusion, a low-dose (0.1-0.5 µg/kg/h) infusion started after induction of anesthesia and continued until 1 h before extubation improved postoperative cognitive function scores on postoperative Day 2 in patients aged 60 years and older.

TRIAL REGISTRATION

URL: www.chictr.org.cn with registration number ChiCTR2100055093, registered on 31/12/2021.