Cerebral Autoregulation Real-Time Monitoring

Neuromonitoring and Neurocognitive Outcomes in Cardiac Surgery: A Narrative Review

Neurocognitive dysfunction after cardiac surgery can present with diverse clinical phenotypes, which include postoperative delirium, postoperative cognitive dysfunction, and stroke, and it presents a significant healthcare burden for both patients and providers. Neurologic monitoring during cardiac surgery includes several modalities assessing cerebral perfusion and oxygenation (near-infrared spectroscopy, transcranial Doppler and jugular venous bulb saturation monitoring) and those that measure cerebral function (processed and unprocessed electroencephalogram), reflecting an absence of a single, definitive neuromonitor. This narrative review briefly describes the technologic basis of these neuromonitoring modalities, before exploring their use in clinical practice, both as tools to predict neurocognitive dysfunction, and with a bundle of interventions designed to optimize cerebral oxygen supply, with the aim of reducing postoperative delirium and cognitive dysfunction following cardiac surgery.

Usefulness of Cerebral Oximetry in TBI by NIRS

Measurement of cerebral oximetry by near-infrared spectroscopy provides continuous and non-invasive information about the oxygen saturation of haemoglobin in the central nervous system. This is especially important in the case of patients with traumatic brain injuries. Monitoring of cerebral oximetry in these patients could allow for the diagnosis of inadequate cerebral oxygenation caused by disturbances in cerebral blood flow. It could enable identification of episodes of hypoxia and cerebral ischemia. Continuous bedside measurement could facilitate the rapid diagnosis of intracranial bleeding or cerebrovascular autoregulation disorders and accelerate the implementation of treatment. However, it should be remembered that the method of monitoring cerebral oximetry by means of near-infrared spectroscopy also has its numerous limitations, resulting mainly from its physical properties. This paper summarizes the usefulness of monitoring cerebral oximetry by near-infrared spectroscopy in patients with traumatic brain injury, taking into account the advantages and the disadvantages of this technique.

Mobile Stroke Units: Current and Future Impact on Stroke Care

Ischemic stroke is a leading cause of death and major disability that impacts societies across the world. Earlier thrombolysis of blocked arteries with intravenous tissue plasminogen activator (tPA) and/or endovascular clot extraction is associated with better clinical outcomes. Mobile stroke units (MSU) can deliver faster tPA treatment and rapidly transport stroke patients to centers with endovascular capabilities. Initial MSU trials in Germany indicated more rapid tPA treatment times using MSUs compared with standard emergency room treatment, a higher proportion of patients treated within 60 minutes of stroke onset, and a trend toward better 3-month clinical outcomes with MSU care. In the United States, the first multicenter, randomized clinical trial comparing standard versus MSU treatment began in 2014 in Houston, TX, and has demonstrated feasibility and safety of MSU operations, reliability of telemedicine technology to assess patients for tPA eligibility without additional time delays, and faster door-to-groin puncture times of MSU patients needing endovascular thrombectomy in interim analysis. Scheduled for completion in 2021, this trial will determine the cost-effectiveness and benefit of MSU treatment on clinical outcomes compared with standard ambulance and hospital treatment. Beyond ischemic stroke, MSUs have additional clinical and research applications that can profoundly impact other cohorts of patients who require time-sensitive neurological care.

Cerebrovascular autoregulation monitoring and patient-centred outcomes after cardiac surgery: a systematic review

BACKGROUND

Impaired cerebrovascular autoregulation (CVAR) is observed in up to 20% of cardiac surgical patients. This systematic review aims to evaluate the association between impaired CVAR, measured by current monitoring techniques, and patient-centred outcomes in adults following cardiac surgery.

METHODS

MEDLINE, EMBASE, PubMed, MEDLINE In-Process and Cochrane Library were systematically searched through 8 December 2017. Studies were included if they assessed associations between CVAR and patient-centred outcomes in the adult cardiac surgical population. The primary outcome of this systematic review was mortality. Secondary outcomes were stroke, delirium and acute kidney injury. Risk of bias was systematically assessed, and the GRADE methodology was used to evaluate the quality of evidence across outcomes.

RESULTS

Eleven observational studies and no randomised controlled trials met the inclusion criteria. Due to methodological heterogeneity, meta-analysis was not possible. There was a high risk of bias within individual studies and low quality of evidence across outcomes. Of the included studies, one assessed mortality, five assessed stroke, four assessed delirium, and three assessed acute kidney injury. No reliable conclusions can be drawn from the one study assessing mortality. Interpretation of studies investigating CVAR and stroke, delirium and acute kidney injury was complicated by the lack of standardisation of monitoring techniques as well as varying definitions of impaired CVAR.

CONCLUSIONS

There is a paucity of high quality evidence for CVAR monitoring and its associations with outcome measures in post-cardiac surgical patients, highlighting the need for future studies.

New Developments in Hypertensive Encephalopathy

PURPOSE OF REVIEW

This review summarizes the latest science on hypertensive encephalopathy and posterior reversible encephalopathy syndrome (PRES). We review the epidemiology and pathophysiology of these overlapping syndromes and discuss best practices for diagnosis and management.

RECENT FINDINGS

Diagnosis of hypertensive encephalopathy largely relies on exclusion of other neurological emergencies. We review the extensive causes of PRES and its imaging characteristics. Management strategies have not changed substantially in the past decade, though newer calcium channel blockers simplify the approach to blood pressure reduction. While this alone may be sufficient for treatment of hypertensive encephalopathy in most cases, management of PRES also depends on modification of other precipitating factors. Hypertensive encephalopathy and PRES are overlapping disorders for which intensive blood pressure lowering is critical. Further research is indicated to both in diagnosis and additional management strategies for these critical conditions.