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Gaspard, N.

Publications and source records attributed to Gaspard, N..

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Hypertonic lactate infusion reduces vasopressor requirement and biomarkers of brain and cardiac injury after experimental cardiac arrest

IntroductionPrognosis after resuscitated cardiac arrest (CA) remains poor with high morbidity and mortality due to extensive cardiac and brain injuries and the lack of effective treatments. Hypertonic sodium lactate (HSL) could be beneficial after CA by buffering severe metabolic acidosis, increasing brain perfusion and cardiac performance, reducing cerebral swelling, and serving as alternative energetic cellular substrate. The aim of this study was therefore to test the effects of HSL infusion on brain and cardiac injury in an experimental model of CA. MethodsAfter a 10-min electrically induced CA followed by 5 min of cardiopulmonary resuscitation maneuvers, adult swine (n=35) were randomly assigned to receive either balanced crystalloids (controls, n=11) or HSL infusion, either starting during cardiopulmonary resuscitation (CPR, Intra-arrest, n=12) or after return of spontaneous circulation (Post-ROSC, n=11) for the following 12 hours. In all animals, extensive multimodal neurological and cardiovascular monitoring was implemented. All animals were treated with target temperature management at 34{degrees}C. Results34 out of 35 (97.1%) animals achieved ROSC and one animal in the Intra-arrest group deceased before completing the observation period. Arterial pH, lactate, sodium concentrations and plasma osmolarity were higher in treated animals then in controls (p<0.001), while potassium concentrations were lower (p=0.004). HSL infusion either Intra-arrest or Post-ROSC improved hemodynamic compared to controls, as shown by reduced vasopressors need to maintain mean arterial pressure target above 65 mmHg (p=0.005 for interaction; p=0.01 for groups). Moreover, plasmatic troponin-I levels and glial fibrillary acid protein (GFAP) concentrations were lower in treated groups at several time-points than in controls. ConclusionsIn this experimental CA model, HSL infusion was associated with reduced vasopressor requirements and decreased plasmatic levels of biomarkers of cardiac and cerebral injury.

neuroscience↗

The Connectivity Index: An Effective Metric for Grading Epileptogenicity

ObjectiveTo investigate the performance of a metric of functional connectivity to classify and grade the excitability of brain regions based on evoked potentials to single pulse electrical stimulation (SPES).\n\nMethodsPatients who received 1-Hz frequency stimulation between 2003 and 2014 at Yale at prospectively selected contacts were included. The stimulated contacts were classified as seizure onset zone (SOZ), highly irritative zone (IZp) or control. Response contacts were classified as seizure onset zone (SOZ), active interictal (IZp), quiet or other. The normalized number of responses was defined as the number of contacts with any evoked responses divided by the total number of recorded contacts, and the normalized distance is the ratio of the average distance between the site of stimulation and sites of evoked responses to the average distances between the site of stimulation and all other recording contacts. A new metric we labeled the connectivity index (CI) is defined as the product of the two values.\n\nResults57 stimulation-sessions in 22-patients were analyzed. The connectivity index (CI) of the SOZ was higher than control (median CI of 0.74 vs. 0.16, p = 0.0002). The evoked responses after stimulation of SOZ were seen at further distance compared to control (median normalized distance 0.96 vs. 0.62, p = 0.0005). It was 1.8 times more likely to record a response at SOZ than in non-epileptic contacts after stimulation of a control site. Habitual seizures were triggered in 27% of patients and 35 % of SOZ contacts (median stimulation intensity 4 mA) but in none of the control or IZp contacts. Non-SOZ contacts in multifocal or poor surgical outcome cases had a higher CI than non-SOZ contacts in those with localizable onsets (medians CI of 0.5 vs. 0.12, p = 0.04). There was a correlation between the stimulation current intensity and the normalized number of evoked responses (r = + 0.49, p 0.01) but not with distance (r = + 0.1, p 0.64)\n\nConclusionsWe found enhanced connectivity when stimulating the SOZ compared to stimulating control contacts; responses were more distant as well. Habitual auras and seizures provoked by SPES were highly predictive of brain sites involved in seizure generation.

neuroscience↗