Can postoperative cognitive dysfunction be avoided?

Dexmedetomidine protects rats from postoperative cognitive dysfunction via regulating the GABAB R-mediated cAMP-PKA-CREB signaling pathway

This work attempts to discuss whether dexmedetomidine (Dex) can protect rats from postoperative cognitive dysfunction (POCD) through regulating the γ-aminobutyric acid-_B receptor (GABA_B R)-mediated cyclic adenosine monophosphate (cAMP) - protein kinase A (PKA) - cAMP-response element binding (cAMP-PKA-CREB) signaling pathway. Sprague-Dawley rats were divided into a non-surgical group (Control), a surgical group (Model), a surgical group treated with Dex (Model + Dex), a surgical group treated with GABA_B R antagonist (Model + CGP 35348) and a surgical group treated with Dex and GABA_B R agonist (Model + Dex + Baclofen). Cognitive and memory functions were evaluated by Y-maze test and open-field test. The neuronal morphology of the hippocampus was observed by hematoxylin and eosin staining and neuronal apoptosis was by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling method. Inflammatory factors and cAMP levels were detected by enzyme-linked immunosorbent assay while expressions of GABA_B R and PKA-CREB pathway-related molecules by Western blot. Compared with control rats, the model rats exhibited reduced alternation rates with a prolonged time spent in the central zone; meanwhile, levels of tumor necrosis factor-α and interleukin-1β and the apoptotic index, as well as GABA_B R1 and GABA_B R2 expressions were increased in the model rats, but the cAMP-PKA-CREB pathway was inhibited (all P < 0.05). When treated with either Dex or CGP 35348, the surgical rats displayed an opposite tendency concerning the above factors as compared to the model rats (all P < 0.05). Furthermore, Baclofen, the agonist of GABA_B R, could reverse the protective effect of Dex against POCD in rats. Dex protects rats from POCD possibly via suppressing GABA_B R to up-regulate the cAMP-PKA-CREB signaling pathway, thereby alleviating the hippocampal inflammation caused by surgical trauma.

Effect of Shenmai injection on cognitive function after cardiopulmonary bypass in cardiac surgical patients: a randomized controlled trial

BACKGROUND

Postoperative cognitive dysfunction (POCD) is a common complication after cardiac surgery that influences the clinical outcomes and quality of life of patients. This study aimed to evaluate the effects of Shenmai injection (SMI) on POCD of patients who underwent cardiac valve replacement under cardiopulmonary bypass (CPB).

METHODS

This prospective, randomized, controlled trial was conducted from September 2014 to January 2017. Eighty-eight patients receiving cardiac valve replacement under CPB were randomized into the control (C) or the SMI (S) group. SMI (0.6 mL/kg) was administered intravenously from the time of anesthesia induction to the beginning of CPB. Cognitive function was assessed at 3 days before surgery and 3 days, 7 days, and 1 month after surgery using the Beijing version of the Montreal Cognitive Assessment (MoCA-BJ) score. The serum levels of neuroglobin (Ngb), hypoxia-inducible factor-1α (HIF-1α), and neuron-specific enolase (NSE) were measured at 30 min after induction (T₀), immediately after the endonasal temperature rewarmed to 36 °C (T₁), and 1 h (T₂), 6 h (T₃), 24 h (T₄), 48 h (T₅), and 72 h (T₆) after CPB.

RESULTS

Compared with the baseline values at T₀, the serum Ngb levels in group C were significantly decreased at T_1-2 and then increased at T_3-6, while the levels in group S were decreased at T_1-2 and increased at T_4-6, compared to group C (p < 0.05). The serum HIF-1α levels at T_1-4 and the serum NSE levels at T_1-6 were significantly increased in both groups (p < 0.05). The serum levels of Ngb at T₃, HIF-1α at T_1-3, and NSE at T_3-4,6 were lower in group S, compared to group C (p < 0.01). The MoCA-BJ scores were decreased at 3 and 7 days after surgery in both groups, and the MoCA-BJ scores in group S were higher than those in group C at 3 and 7 days after surgery (p < 0.01).

CONCLUSION

Cognitive function is impaired postoperatively in patients who have undergone cardiac valve replacement under CPB. In addition, treatment with the traditional Chinese medicine SMI decreases the serum levels of Ngb, HIF-1α, and NSE as well as attenuates cognitive dysfunction.

TRIAL REGISTRATION

This trial was registered with Clinicaltrials.gov as ChiCTR-TRC-14004373 on March 11, 2014.

Association between changes in cerebral grey matter volume and postoperative cognitive dysfunction in elderly patients: study protocol for a prospective observational cohort study

Background

Cognitive decline is frequently observed in elderly patients after major surgery. The pathophysiology of postoperative cognitive dysfunction (POCD) remains unclear. The aim of our investigation is to identify potential associations between brain volume change and POCD in elderly patients undergoing major surgery.

Methods

This is a prospective observational cohort study approved by the regional ethics board. We intend to compare specific brain volumes (hippocampus, lateral ventricle, total grey matter volume, regional cortical thickness) on magnetic resonance imaging and cognitive functions determined by a neuropsychological assessment battery in 70 study participants aged ≥65 years before and 3 and 12 months after major noncardiac surgery. Thirty volunteers will be included as matched nonsurgical controls. The primary endpoint of the study is the change in hippocampal volume over time in patients with and without POCD. The secondary endpoint is the correlation between the change in cerebral volume and cognitive function. We will follow the STROBE guidelines for reporting the results of observational studies.

Discussion

We hypothesize that surgery under general anesthesia is associated with a loss of cerebral grey matter, and that the degree of postoperative cognitive dysfunction correlates with the extent of atrophy in areas of the brain that are relevant for cognitive functions. The validation of reproducible anatomical biomarkers, such as the specific brain volumes examined in our cohort, may serve to evaluate the effect of preventive strategies and treatment interventions for POCD in follow-up studies.

Trial registration

Clinicaltrials.gov NCT02045004. Registered 22 January 2014. Kofam.ch SNCTP000001751. Registered 21 April 2016 (retrospectively registered).