Quantitative Pupillometry in the Intensive Care Unit.

Quantitative pupillometry provides a noninvasive and objective assessment within the neurological examination. This review details the physiology of the pupillary light response, the clinical significance of changes in pupillary reactivity, and the variables that compose the Neurological Pupil index or NPi are discussed. This article reviews the most recent applications and advances in quantitative pupillometry for noninvasive intracranial pressure monitoring, postcardiac arrest prognostication, and subarachnoid hemorrhage. Also discussed are the limitations and confounders of quantitative pupillometry in the modern neurological intensive care unit.

Comparative Studies of Cerebral Reperfusion Injury in the Posterior and Anterior Circulations After Mechanical Thrombectomy.

Cerebral reperfusion injury is the major complication of mechanical thrombectomy (MT) for acute ischemic stroke (AIS). Contrast extravasation (CE) and intracranial hemorrhage (ICH) are the key radiographical features of cerebral reperfusion injury. The aim of this study was to investigate CE and ICH after MT in the anterior and posterior circulation, and their effect on functional outcome. This is a retrospective study of all consecutive patients who were treated with MT for AIS at University of California Irvine Medical Center between January 1, 2014, and December 31, 2017. Patient characteristics, clinical features, procedural variables, contrast extravasation, ICH, and outcomes after MT were analyzed. A total of 131 patients with anterior circulation (AC) stroke and 25 patients with posterior circulation (PC) stroke underwent MT during the study period. There was no statistically significant difference in admission NIHSS score, blood pressure, rate of receiving intravenous tPA, procedural variables, contrast extravasation, and symptomatic ICH between the 2 groups. Patients with PC stroke had a similar rate of favorable outcome (mRS 0-2) but significantly higher mortality (40.0% vs. 10.7%, p < 0.01) than patients with AC stroke. Multivariate regression analysis identified initial NIHSS score (OR 1.1, CI 1.0-1.2, p = 0.01), number of passes with stent retriever (OR 2.1, CI 1.3-3.6, p < 0.01), and PC stroke (OR 9.3, CI 2.5-35.1, p < 0.01) as independent risk factors for death. There was no significant difference in functional outcomes between patients with and without evidence of cerebral reperfusion injury after MT. We demonstrated that AC and PC stroke had similar rates of cerebral reperfusion injury and favorable outcome after MT. Cerebral reperfusion injury is not a significant independent risk factor for poor functional outcome.

Refractory Central Neurogenic Hyperventilation: A Novel Approach Utilizing Mechanical Dead Space.

This report describes the successful management of a case of central neurogenic hyperventilation (CNH) refractory to high dose sedation by increasing the mechanical dead space. A 46-year-old male presented with a history of multiple neurological symptoms. Following an extensive evaluation, he was diagnosed with primary diffuse CNS lymphoma and started on high dose steroids. After initial symptomatic improvement, the patient developed increasing respiratory distress and tachypnea. He was intubated and transferred to the neurointensive care unit (neuro ICU). While in the ICU the patient remained ventilator dependent with significant tachypnea and respiratory alkalosis resistant to fentanyl and propofol. This prompted an attempt to normalize the PaCO2 via an increase of the mechanical dead space. This approach successfully increased PaCO2 and bridged the patient until ongoing therapy for the underlying disease resolved the pervasive breathing pattern typical of CNH. Further investigation is warranted to evaluate this strategy, which upon review of the literature appears underused.

Seed-mediated co-reduction: a versatile route to architecturally controlled bimetallic nanostructures.

Gold-palladium octopods and new concave and shape-controlled alloy nanostructures are synthesized by seed-mediated co-reduction, wherein two metal precursors are reduced in the presence of seeds that serve as preferential sites for the growth of the larger nanostructures. Here, the first comprehensive study of this technique is presented in a model Au-Pd system and provides insight into the mechanism of formation for these architecturally distinct nanocrystals. A systematic evaluation of synthesis conditions decoupled the roles of (i) Au:Pd precursor ratio, (ii) reaction pH, and (iii) capping agent concentration in morphology development. These factors provide control of growth kinetics and ultimately the morphology and composition of the final nanostructures. Significantly, elucidating the overgrowth processes during seed-mediated co-reduction will lead to the synthesis of other architecturally controlled bimetallic nanocrystals.