The Importance of Neuromonitoring in Non Brain Injured Patients

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency Medicine 2022. Other selected articles can be found online at https://www.biomedcentral.com/collections/annualupdate2022. Further information about the Annual Update in Intensive Care and Emergency Medicine is available from https://link.springer.com/bookseries/8901.

Cerebral microemboli during extracorporeal life support: a single-centre cohort study

OBJECTIVES

The aim of this study was to investigate the load and composition of cerebral microemboli in adult patients undergoing venoarterial extracorporeal life support (ECLS).

METHODS

Adult ECLS patients were investigated for the presence of cerebral microemboli and compared to critically ill, pressure-controlled ventilated controls and healthy volunteers. Cerebral microemboli were detected in both middle cerebral arteries for 30 min using transcranial Doppler ultrasound. Neurological outcome (ischaemic stroke, global brain ischaemia, intracerebral haemorrhage, seizure, metabolic encephalopathy, sensorimotor sequelae and neuropsychiatric disorders) was additionally evaluated.

RESULTS

Twenty ECLS patients (cannulations: 15 femoro-femoral, 4 femoro-subclavian, 1 femoro-aortic), 20 critically ill controls and 20 healthy volunteers were analysed. ECLS patients had statistically significantly more cerebral microemboli than critically ill controls {123 (43-547) [median (interquartile range)] vs 35 (16-74), difference: 88 [95% confidence interval (CI) 19-320], P = 0.023} and healthy volunteers [11 (5-12), difference: 112 (95% CI 45-351), P < 0.0001]. In ECLS patients, 96.5% (7346/7613) of cerebral microemboli were of gaseous composition, while solid cerebral microemboli [1 (0-5)] were detected in 12 out of 20 patients. ECLS patients had more neurological complications than critically ill controls (12/20 vs 3/20, P = 0.003). In ECLS patients, a high microembolic rate (>100/30 min) tended to be associated with neurological complications including ischaemic stroke, neuropsychiatric disorders, sensorimotor sequelae and non-convulsive status epilepticus (odds ratio 4.5, 95% CI 0.46-66.62; P = 0.559).

CONCLUSIONS

Our results indicate that adult ECLS patients are continuously exposed to many gaseous and, frequently, to few solid cerebral microemboli. Prolonged cerebral microemboli formation may contribute to neurological morbidity related to ECLS treatment.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, NCT02020759, https://clinicaltrials.gov/ct2/show/NCT02020759?term=erdoes&rank=1.

Cerebral Perfusion and Brain Oxygen Saturation Monitoring with: Jugular Venous Oxygen Saturation, Cerebral Oximetry, and Transcranial Doppler Ultrasonography

Accumulating evidence indicates that cerebral desaturation in the perioperative period occurs more frequently than recognized. Combining monitoring modalities that reflect different aspects of cerebral perfusion status, such as near-infrared spectroscopy, jugular bulb saturation, and transcranial Doppler ultrasonography, may provide an extended window for prevention, early detection, and prompt intervention in ongoing hypoxic/ischemic neuronal injury and, thereby, improve neurologic outcome. Such an approach would minimize the impact of limitations of each monitoring modality, while individual components complement each other, enhancing the accuracy of acquired information. Current literature has failed to demonstrate any clear-cut clinical benefit of these modalities on outcome prognosis.

Causes and consequences of baseline cerebral blood flow reductions in Alzheimer's disease

Reductions of baseline cerebral blood flow (CBF) of ∼10-20% are a common symptom of Alzheimer's disease (AD) that appear early in disease progression and correlate with the severity of cognitive impairment. These CBF deficits are replicated in mouse models of AD and recent work shows that increasing baseline CBF can rapidly improve the performance of AD mice on short term memory tasks. Despite the potential role these data suggest for CBF reductions in causing cognitive symptoms and contributing to brain pathology in AD, there remains a poor understanding of the molecular and cellular mechanisms causing them. This review compiles data on CBF reductions and on the correlation of AD-related CBF deficits with disease comorbidities (e.g. cardiovascular and genetic risk factors) and outcomes (e.g. cognitive performance and brain pathology) from studies in both patients and mouse models, and discusses several potential mechanisms proposed to contribute to CBF reductions, based primarily on work in AD mouse models. Future research aimed at improving our understanding of the importance of and interplay between different mechanisms for CBF reduction, as well as at determining the role these mechanisms play in AD patients could guide the development of future therapies that target CBF reductions in AD.

Regional Cerebral Oxygen Saturation Decreases During Primary Hip Arthroplasty: An Analysis of Perioperative Regional Cerebral Oxygenation (rSO2), S100 Calcium-Binding Protein B (S100B) and Glial Fibrillary Acidic Protein (GFAP) Values. A Pilot Study

Background

The incidence of postoperative cognitive dysfunction (POCD) after major joint arthroplasty is high. In the etiology of POCD, many factors have been cited, including thromboembolic complications. The incidence of cerebral embolization after lower extremity arthroplasty may be as high as 40–60%. The potential events of cerebral embolization could lead to a decrease in the regional cerebral oxygenation (rSO₂) and increased serum levels of biochemical markers of brain damage. The objective of the study was to test whether there are any changes in the rSO₂ values and serum markers of brain damage in patients who underwent total hip arthroplasty.

Material/Methods

Fifteen patients who underwent primary hip arthroplasty under spinal anesthesia were analyzed. The rSO₂ was monitored using infrared spectroscopy. Biochemical analyses of S100 calcium-binding protein B (S100B) protein and fibrillary acidic protein (GFAP) serum concentrations were performed using immunoassay methods.

Results

The values of rSO₂ decreased during the surgery, but this was not related to mean arterial pressure variations or hemoglobin saturation. The concentration of S100B was increased compared to its preoperative values, and there were no changes in GFAP values. The changes in rSO₂ readings correlated with the biomarkers’ levels just after the surgery.

Conclusions

Our results suggest that S100B may be a more specific marker of astroglial damage in patients after primary total hip arthroplasty. The decrease in rSO₂ readings may be due to micro-thromboembolic events that occurred during the surgery. However, the results of this study are preliminary, and further studies are needed to establish its clinical efficacy.