Preoperative ketamine administration for prevention of postoperative neurocognitive disorders after major orthopedic surgery in elderly patients: A multicenter randomized blinded placebo-controlled trial.

BACKGROUND: Preventive anesthetic impact on the high rates of postoperative neurocognitive disorders in elderly patients is debated. The Prevention of postOperative Cognitive dysfunction by Ketamine (POCK) study aimed to assess the effect of ketamine on this condition. METHODS: This is a multicenter, randomized, double-blind, interventional study. Patients ≥60 years undergoing major orthopedic surgery were randomly assigned in a 1:1 ratio to receive preoperative ketamine 0.5 mg/kg as an intravenous bolus (n = 152) or placebo (n = 149) in random blocks stratified according to the study site, preoperative cognitive status and age. The primary outcome was the proportion of objective delayed neurocognitive recovery (dNR) defined as a decline of one or more neuropsychological assessment standard deviations on postoperative day 7. Secondary outcomes included a three-month incidence of objective postoperative neurocognitive disorder (POND), as well as delirium, anxiety, and symptoms of depression seven days and three months after surgery. RESULTS: Among 301 patients included, 292 (97%) completed the trial. Objective dNR occurred in 50 (38.8%) patients in the ketamine group and 54 (40.9%) patients in the placebo group (OR [95% CI] 0.92 [0.56;1.51], p = 0.73) on postoperative day 7. Incidence of objective POND three months after surgery did not differ significantly between the two groups nor did incidence of delirium, anxiety, apathy, and fatigue. Symptoms of depression were less frequent in the ketamine group three months after surgery (OR [95%CI] 0.34 [0.13-0.86]). CONCLUSIONS: A single preoperative bolus of intravenous ketamine does not prevent the occurrence of dNR or POND in elderly patients scheduled for major orthopedic surgery. (Clinicaltrials.gov NCT02892916.).

Goal-Directed Fluid Therapy and major postoperative complications in elective craniotomy. A retrospective analysis of a before-after multicentric study.

BACKGROUND: Goal-Directed Fluid Therapy (GDFT) is recommended to decrease major postoperative complications. However, data are lacking in intra-cranial neurosurgery. METHODS: We evaluated the efficacy of a GDFT protocol in a before/after multi-centre study in patients undergoing elective intra-cranial surgery for brain tumour. Data were collected during 6 months in each period (before/after). GDFT was performed in high-risk patients: ASA score III/IV and/or preoperative Glasgow Coma Score (GCS) < 15 and/or history of brain tumour surgery and/or tumour greater size ≥ 35 mm and/or mid-line shift ≥ 3 mm and/or significant haemorrhagic risk. Major postoperative complication was a composite endpoint: re-intubation after surgery, a new onset of GCS < 15 after surgery, focal motor deficit, agitation, seizures, intra-cranial haemorrhage, stroke, intra-cranial hypertension, hospital-acquired related pneumonia, surgical site infection, cardiac arrythmia, invasive mechanical ventilation ≥ 48 h and in-hospital mortality. RESULTS: From July 2018 to January 2021, 344 patients were included in 3 centers: 171 in the before and 173 in the after (GDFT) period. Thirty-six (21.1%) patients displayed a major postoperative complication in the Before period, and 50 (28.9%) in the After period (p = 0.1). In the propensity score analysis, we matched 48 patients in each period: 9 (18.8%) patients in the After period and 14 (29.2%) patients in the Before period displayed a major perioperative complication (p = 0.2). Sixty-two (35.8%) patients received GDFT in the After period, with great heterogeneity among centers (p < 0.05). CONCLUSIONS: In our before-after study, GDFT was not associated with a decrease in postoperative major complications in elective intra-cranial neurosurgery.

Intraoperative management of brain-dead organ donors by anesthesiologists during an organ procurement procedure: results from a French survey.

BACKGROUND: This study aimed at describing usual anesthetic practices for brain-dead donors (BDD) during an organ procurement (OP) procedure and to assess the knowledge and self-confidence of French anesthesiologists with this practice. METHODS: An electronic and anonymous survey with closed-questions about anesthetic management of BDD was distributed to French anesthesiologists via the mailing list of the French Society of Anesthesiology and Intensive Care Medicine. RESULTS: Four hundred fifty-eight responses were analyzed. Respondents were mainly attending physicians with more than 10 years of clinical experience. 78% of them declared being cognizant of guidelines regarding management of BDD. Advanced hemodynamic monitoring and endocrine substitution were rarely considered by respondents (31 and 35% of respondents, respectively). 98% of the respondents used crystalloids for fluid resuscitation. During the procedure, use of neuromuscular blockers, opioids and sedative agents were considered by respectively 84, 61 and 27% of the respondents. A very high level of agreement (10 [8-10], on a ten-points Likert-style scale) was reported concerning the expected impact of intraoperative anesthetic management on the primary function of grafts. CONCLUSIONS: Declared anesthetic practice appeared in accordance with guidelines concerning organ donor management in the ICU. Further studies are needed to evaluate the specific impact of intraoperative management during this procedure and thus the need for specific anesthetic guidelines.

Posterior reversible encephalopathy syndrome associated with reversible cerebral vasoconstriction syndrome in a patient presenting with postpartum eclampsia: A case report.

Posterior reversible encephalopathy syndrome (PRES) and reversible cerebral vasoconstriction (RCVS) are rare neurological disorders with complex physiopathology which is not yet fully understood. We present here the case of a 31-year-old woman with a bi-amniotic bi-chorial pregnancy who developed immediate postpartum eclampsia after vaginal delivery, associated with RCVS and PRES. Although post-partum is a well-known precipitating factors for these diseases, to our knowledge, there are only few similar cases reported with the association of these syndromes. Repeated MRI scans were instrumental in the final diagnosis of RCVS associated with PRES, allowing us to give the patient the appropriate treatment. These two syndromes have similar symptoms but may have different treatments, thus highlighting the importance of a correct diagnosis.

Prediction Score for Postoperative Neurologic Complications after Brain Tumor Craniotomy: A Multicenter Observational Study.

WHAT WE ALREADY KNOW ABOUT THIS TOPIC: WHAT THIS ARTICLE TELLS US THAT IS NEW: BACKGROUND:: Craniotomy for brain tumor displays significant morbidity and mortality, and no score is available to discriminate high-risk patients. Our objective was to validate a prediction score for postoperative neurosurgical complications in this setting. METHODS: Creation of a score in a learning cohort from a prospective specific database of 1,094 patients undergoing elective brain tumor craniotomy in one center from 2008 to 2012. The validation cohort was validated in a prospective multicenter independent cohort of 830 patients from 2013 to 2015 in six university hospitals in France. The primary outcome variable was postoperative neurologic complications requiring in-intensive care unit management (intracranial hypertension, intracranial bleeding, status epilepticus, respiratory failure, impaired consciousness, unexpected motor deficit). The least absolute shrinkage and selection operator method was used for potential risk factor selection with logistic regression. RESULTS: Severe complications occurred in 125 (11.4%) and 90 (10.8%) patients in the learning and validation cohorts, respectively. The independent risk factors for severe complications were related to the patient (Glasgow Coma Score before surgery at or below 14, history of brain tumor surgery), tumor characteristics (greatest diameter, cerebral midline shift at least 3 mm), and perioperative management (transfusion of blood products, maximum and minimal systolic arterial pressure, duration of surgery). The positive predictive value of the score at or below 3% was 12.1%, and the negative predictive value was 100% in the learning cohort. In-intensive care unit mortality was observed in eight (0.7%) and six (0.7%) patients in the learning and validation cohorts, respectively. CONCLUSIONS: The validation of prediction scores is the first step toward on-demand intensive care unit admission. Further research is needed to improve the score's performance before routine use.

Role of microglia in a mouse model of paediatric traumatic brain injury.

The cognitive and behavioural deficits caused by traumatic brain injury (TBI) to the immature brain are more severe and persistent than TBI in the mature brain. Understanding this developmental sensitivity is critical as children under four years of age sustain TBI more frequently than any other age group. Microglia (MG), resident immune cells of the brain that mediate neuroinflammation, are activated following TBI in the immature brain. However, the type and temporal profile of this activation and the consequences of altering it are still largely unknown. In a mouse model of closed head weight drop paediatric brain trauma, we characterized i) the temporal course of total cortical neuroinflammation and the phenotype of ex vivo isolated CD11B-positive microglia/macrophage (MG/MΦ) using a battery of 32 markers, and ii) neuropathological outcome 1 and 5days post-injury. We also assessed the effects of targeting MG/MΦ activation directly, using minocycline a prototypical microglial activation antagonist, on these processes and outcome. TBI induced a moderate increase in both pro- and anti-inflammatory cytokines/chemokines in the ipsilateral hemisphere. Isolated cortical MG/MΦ expressed increased levels of markers of endogenous reparatory/regenerative and immunomodulatory phenotypes compared with shams. Blocking MG/MΦ activation with minocycline at the time of injury and 1 and 2days post-injury had only transient protective effects, reducing ventricular dilatation and cell death 1day post-injury but having no effect on injury severity at 5days. This study demonstrates that, unlike in adults, the role of MG/MΦ in injury mechanisms following TBI in the immature brain may not be negative. An improved understanding of MG/MΦ function in paediatric TBI could support translational efforts to design therapeutic interventions.

Characterization of phenotype markers and neuronotoxic potential of polarised primary microglia in vitro.

Microglia mediate multiple facets of neuroinflammation, including cytotoxicity, repair, regeneration, and immunosuppression due to their ability to acquire diverse activation states, or phenotypes. Modulation of microglial phenotype is an appealing neurotherapeutic strategy but a comprehensive study of classical and more novel microglial phenotypic markers in vitro is lacking. The aim of this study was to outline the temporal expression of a battery of phenotype markers from polarised microglia to generate an in vitro tool for screening the immunomodulatory potential of novel compounds. We characterised expression of thirty-one macrophage/microglial phenotype markers in primary microglia over time (4, 12, 36, and 72 h), using RT-qPCR or multiplex protein assay. Firstly, we selected Interleukin-4 (IL-4) and lipopolysaccharide (LPS) as the strongest M1-M2 polarising stimuli, from six stimuli tested. At each time point, markers useful to identify that microglia were M1 included iNOS, Cox-2 and IL-6 and a loss of M2a markers. Markers useful for quantifying M2b-immunomodulatory microglia included, increased IL-1RA and SOCS3 and for M2a-repair and regeneration, included increased arginase-1, and a loss of the M1 and M2b markers were discriminatory. Additional markers were regulated at fewer time points, but are still likely important to monitor when assessing the immunomodulatory potential of novel therapies. Further, to facilitate identification of how novel immunomodulatory treatments alter the functional affects of microglia, we characterised how the soluble products from polarised microglia affected the type and rate of neuronal death; M1/2b induced increasing and M2a-induced decreasing neuronal loss. We also assessed any effects of prior activation state, to provide a way to identify how a novel compound may alter phenotype depending on the stage of injury/insult progression. We identified generally that a prior M1/2b reduced the ability of microglia to switch to M2a. Altogether, we have characterised a profile of phenotype markers and a mechanism of assessing functional outcome that we can use as a reference guide for first-line screening of novel immunomodulatory therapies in vitro in the search for viable neuroprotectants.

Activation of microglial N-methyl-D-aspartate receptors triggers inflammation and neuronal cell death in the developing and mature brain.

OBJECTIVE: Activated microglia play a central role in the inflammatory and excitotoxic component of various acute and chronic neurological disorders. However, the mechanisms leading to their activation in the latter context are poorly understood, particularly the involvement of N-methyl-D-aspartate receptors (NMDARs), which are critical for excitotoxicity in neurons. We hypothesized that microglia express functional NMDARs and that their activation would trigger neuronal cell death in the brain by modulating inflammation. METHODS AND RESULTS: We demonstrate that microglia express NMDARs in the murine and human central nervous system and that these receptors are functional in vitro. We show that NMDAR stimulation triggers microglia activation in vitro and secretion of factors that induce cell death of cortical neurons. These damaged neurons are further shown to activate microglial NMDARs and trigger a release of neurotoxic factors from microglia in vitro, indicating that microglia can signal back to neurons and possibly induce, aggravate, and/or maintain neurologic disease. Neuronal cell death was significantly reduced through pharmacological inhibition or genetically induced loss of function of the microglial NMDARs. We generated Nr1 LoxP(+/+) LysM Cre(+/-) mice lacking the NMDAR subunit NR1 in cells of the myeloid lineage. In this model, we further demonstrate that a loss of function of the essential NMDAR subunit NR1 protects from excitotoxic neuronal cell death in vivo and from traumatic brain injury. INTERPRETATION: Our findings link inflammation and excitotoxicity in a potential vicious circle and indicate that an activation of the microglial NMDARs plays a pivotal role in neuronal cell death in the perinatal and adult brain.

Dexmedetomidine: new insights.

Dexmedetomidine is a potent alpha-2-adrenergic agonist, more selective than clonidine, with widespread actions on the mammalian brain that include sedation, anaesthetic-sparing, analgesia and sympatholytic properties. A large body of recent work supports its favourable profile in improving outcome and long-term brain function in the critically ill. The source of these benefits may lie in the neuroprotective properties that are seen in experimental models and in the clinical setting, in which it can attenuate delirium, preserve sleep architecture, preserve ventilatory drive and decrease sympathetic tone and inflammatory response. Dexmedetomidine may also be a valuable adjuvant when regional anaesthesia is used. Future research should aim at establishing the risk/benefit ratio when used at the bedside.