The effect of burst suppression on cerebral blood flow and autoregulation: a scoping review of the human and animal literature

Background: Burst suppression (BS) is an electroencephalography (EEG) pattern in which there are isoelectric periods interspersed with bursts of cortical activity. Targeting BS through anaesthetic administration is used as a tool in the neuro-intensive care unit but its relationship with cerebral blood flow (CBF) and cerebral autoregulation (CA) is unclear. We performed a systematic scoping review investigating the effect of BS on CBF and CA in animals and humans. Methods: We searched MEDLINE, BIOSIS, EMBASE, SCOPUS and Cochrane library from inception to August 2022. The data that were collected included study population, methods to induce and measure BS, and the effect on CBF and CA. Results: Overall, there were 66 studies that were included in the final results, 41 of which examined animals, 24 of which examined humans, and 1 of which examined both. In almost all the studies, BS was induced using an anaesthetic. In most of the animal and human studies, BS was associated with a decrease in CBF and cerebral metabolism, even if the mean arterial pressure remained constant. The effect on CA during periods of stress (hypercapnia, hypothermia, etc.) was variable. Discussion: BS is associated with a reduction in cerebral metabolic demand and CBF, which may explain its usefulness in patients with brain injury. More evidence is needed to elucidate the connection between BS and CA.

Treatment of Acute Stroke: Current Practices and Future Horizons

PURPOSE

This review will discuss revascularization of acute ischemic stroke (AIS), discussing the concept of the ischemic penumbra and how thrombolysis and thrombectomy take advantage of it.

SUMMARY

The goal of AIS revascularization is to rescue the ischemic penumbra and the approach to has gone from a time-based to tissue-based approach. Patients must be carefully selected for thrombolysis, which traditionally was limited to those whose last known normal time (LKNT) was known and within 4.5 h. However, newer imaging techniques involving MRI and CT perfusion (CTP) can select patients for thrombolysis whose LKNT is unknown. Alteplase, or tPA, is still the agent of choice for thrombolysis in patients with AIS but tenecteplase (TNK) may be just as effective and more efficient to use. Endovascular thrombectomy (EVT) has shown considerable efficacy for treating large-vessel occlusions and using CTP, patients can be selected for hours after symptom-onset if viable tissue remains. Further research is underway to determine if EVT can be used for medium vessel occlusions and for basilar artery thromboses as well as to determine whether an "EVT-alone" strategy is superior to "tPA + EVT" strategy.

Transfusions in patients with iron deficiency anemia following release of Choosing Wisely Guidelines

BACKGROUND

In 2016, based on recommendations of the American Association of Blood Banks (AABB), Choosing Wisely Canada released transfusion guidelines for patients with Iron Deficiency Anemia. The goal of the present study was to examine the number of transfusions given in Calgary emergency departments (EDs) before and after the release of these guidelines.

METHODS

We analyzed 11,786 anemia encounters from January 2014 to December 2019. A transfusion was considered potentially avoidable if the patient's hemoglobin was > 70 g/L and if the patient was hemodynamically stable. We used time-series analyses to examine change in rate of total and potentially avoidable transfusions quarterly over the total and pre and post intervention periods.

RESULTS

In total, 1409/11,786 (12.0%) of the encounters received transfusions; 80.0% (1127/1409) were indicated while 19.9% (281/1409) were potentially avoidable. In the pre-intervention period, the rate of potentially avoidable transfusions was 21.5% (133/618) and in the post-intervention period, the rate of potentially avoidable transfusions was 18.7% (148/791). The rate of potentially avoidable transfusions decreased quarterly at a rate of 0.3% which did not reach statistical significance (p = 0.06).

DISCUSSION

Our data suggest that the number of potentially avoidable transfusions has not decreased since the release of Choosing Wisely Canada guidelines and local educational initiatives. This may be due to the fact that there is a pre-existing down trend in the number of transfusions provided.