Essential Noninvasive Multimodality Neuromonitoring for the Critically Ill Patient

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency Medicine 2020. Other selected articles can be found online at . Further information about the Annual Update in Intensive Care and Emergency Medicine is available from

The influence of metakaolin substitution by slag in alkali-activated inorganic binders for civil engineering

V této studii byl zkoumán účinek náhrady metakaolínu mletou vysokopecní struskou v alkalickém geopolymerním pojivu z pohledu jejich reologických a mechanických vlastností. Bylo prokázáno, že přidávání strusky do pojiva může zlepšit mechanické vlastnosti konečných produktů. Naše zkoumání bylo zaměřeno na široký interval substituce metakaolinů v rozmezí od 100 do 40 objemových procent metakaolinu, kdy objem pevných látek v konečném pojivu zůstal konstantní. Připravená pojidla byla aktivována alkalickým roztokem křemičitanu draselného s křemičitanovým modulem 1,61. Analýzy velikosti částic byly prováděny pro stanovení distribuce velikosti částic. Reologické vlastnosti byly stanoveny v souladu s průtokovými vlastnostmi měřeními na Fordově výtokovém poháru a oscilačním měřením procesu vytvrzování. Pro zkoumání procesu vytvrzování byla v geometrii rovinných desek použita oscilační reometrie s malou amplitudou řízená deformací. Pro stanovení aplikačních mechanických vlastností byly pojiva plněna keramickým ostřivem v rozmezí zrnitosti 0-1 mm. Plnění bylo udržováno konstantních 275 objemových procent vzhledem k suchému pojivu. Mechanické vlastnosti byly zkoumány po 1, 7 a 28 dnech a mikrostruktura byla dokumentována rastrovací elektronovou mikroskopií. Výsledky ukazují, že přídavek strusky má příznivý účinek nejen na mechanické vlastnosti tvrzeného pojiva, ale také na tokové vlastnosti čerstvé geopolymerní pasty a následné kinetiky vytvrzení alkalicky aktivovaných pojiv.In this study the effect of metakaolin replacement by milled blast furnace slag in alkali-activated geopolymeric binder was investigated in accordance to their rheological and mechanical properties. It was demonstrated that slag addition into the metakaolin binder can improve mechanical properties of final products. Our investigation was focused on broad interval of metakaolin substitution in the range from 100 to 40 volume per cents of metakaolin so that the volume content of solids in final binder was maintained constant. Prepared binders were activated by alkaline solution of potassium silicate with silicate module of 1.61. The particle size analyses were performed for determination of particle size distribution. The rheological properties were determined in accordance to flow properties by measurements on Ford viscosity cup and by oscillatory measurements of hardening process. For the investigation of hardening process, the strain controlled small amplitude oscillatory rheometry was used in plane-plate geometry. For determination of applied mechanical properties were binders filled by ceramic grog in the granularity range 0-1 mm. The filling was maintained constant at 275 volume per cents in accordance to ratio of solids in dry binder. The mechanical properties were investigated after 1, 7 and 28 days and microstructure was documented by scanning electron microscopy. The results indicate that slag addition have beneficial effect not only on mechanical properties of hardened binder but also on flow properties of fresh geopolymer paste and subsequent hardening kinetics of alkali-activated binders

A Brain-Machine Interface for Control of Medically-Induced Coma

Medically-induced coma is a drug-induced state of profound brain inactivation and unconsciousness used to treat refractory intracranial hypertension and to manage treatment-resistant epilepsy. The state of coma is achieved by continually monitoring the patient's brain activity with an electroencephalogram (EEG) and manually titrating the anesthetic infusion rate to maintain a specified level of burst suppression, an EEG marker of profound brain inactivation in which bursts of electrical activity alternate with periods of quiescence or suppression. The medical coma is often required for several days. A more rational approach would be to implement a brain-machine interface (BMI) that monitors the EEG and adjusts the anesthetic infusion rate in real time to maintain the specified target level of burst suppression. We used a stochastic control framework to develop a BMI to control medically-induced coma in a rodent model. The BMI controlled an EEG-guided closed-loop infusion of the anesthetic propofol to maintain precisely specified dynamic target levels of burst suppression. We used as the control signal the burst suppression probability (BSP), the brain's instantaneous probability of being in the suppressed state. We characterized the EEG response to propofol using a two-dimensional linear compartment model and estimated the model parameters specific to each animal prior to initiating control. We derived a recursive Bayesian binary filter algorithm to compute the BSP from the EEG and controllers using a linear-quadratic-regulator and a model-predictive control strategy. Both controllers used the estimated BSP as feedback. The BMI accurately controlled burst suppression in individual rodents across dynamic target trajectories, and enabled prompt transitions between target levels while avoiding both undershoot and overshoot. The median performance error for the BMI was 3.6%, the median bias was -1.4% and the overall posterior probability of reliable control was 1 (95% Bayesian credibility interval of [0.87, 1.0]). A BMI can maintain reliable and accurate real-time control of medically-induced coma in a rodent model suggesting this strategy could be applied in patient care.National Institutes of Health (U.S.) (Director's Transformative Award R01 GM104948)National Institutes of Health (U.S.) (Pioneer Award DP1-OD003646)National Institutes of Health (U.S.) (NIH K08-GM094394)Massachusetts General Hospital. Dept. of Anesthesia and Critical Car