Cardiac output monitoring with thermodilution pulse-contour analysis vs. non-invasive pulse-contour analysis.

Intravenous fluid boluses guided by changes in stroke volume improve some outcomes after major surgery, but invasive measurments may limit use. From October 2016 to May 2018, we compared the agreement and trending ability of a photoplethysmographic device (Clearsight) with a PiCCO, calibrated by thermodilution, for haemodynamic variables in 20 adults undergoing major elective surgery. We analysed 4519 measurement pairs, including before and after 68 boluses of 250 ml crystalloid. The bias and precision of stroke volume measurement by Clearsight were -0.89 ± 4.78 ml compared with the invasive pulse-contour cardiac output device. The coefficient of agreement for stroke volume variation after fluid boluses between the two devices was 0.79 ('strong'). Fluid boluses that increased stroke volume by ≥ 10% increased mean absolute volume (SD) and mean percentage (SD) stroke volume measurements similarly for the invasive pulse-contour cardiac output and Clearsight devices: 9 (4) ml vs. 8 (4) ml and 16% (8%) vs. 15% (10%), respectively, p > 0.05. The non-invasive Clearsight pulse-contour analysis was similar to an invasive pulse-contour device in measuring absolute and changing stroke volumes during major surgery.

Neural correlates of consciousness and related disorders: From phenotypic descriptors of behavioral and relative consciousness to cortico-subcortical circuitry.

We report a review of medical aspects of the consciousness. The behavioral dimension, phenotypic descriptors, relative consciousness and neural correlates of consciousness and related disorders were addressed successively in a holistic and chronological approach. Consciousness is relative, specific to each individual across time and space. Historically defined as the perception of the self and the environment, it cannot be separated from behaviors, entailing an idea of conscious behavior with metapractic and metagnostic aspects. Observation of spontaneous and evoked overt behavior distinguishes three main types of disorder of consciousness (DoC): coma, vegetative state or unresponsive wakefulness, and minimally conscious or relationally impoverished state. Modern functional exploration techniques, such as imaging, increase the understanding of DoCs and consciousness. Whether consciousness is a superior function and/or an instrumental function is discussed. Neural correlates can be subdivided into two wakefulness pathways (superior thalamic cholinergic and inferior extra-thalamic), and cortico-subcortical circuitry. The deep brain structures are those described in the well-known sensorimotor, associative and limbic loops, as illustrated in the mesolimbic model of DoC. The cortices can be segregated into several overlapping networks: (1) a global workspace including thalamo-cortical loops; (2) the default mode network (DMN) and related intrinsic connectivity networks (i.e., central executive, medial DMN and salience networks); (3) a 3-fold network comprising the fronto-parietal control system and its dorsal and ventral attentional sub-networks, the fronto-parietal executive control network, and the cingulo-opercular salience network; (4) the internal and external cortices, respectively medial, turned toward the self, and lateral, turned toward the environment. The network dynamics is the reflection of consciousness, notably anticorrelations such as the decrease in activity of the posterior cingulate-precuneus regions during attentional tasks. Thanks to recent advances in DoC pathophysiology, further significative therapeutic progress is expected, taking into account the societal context. This depends notably on the dissemination of medical knowledge and its transfer to a wider public.

[Medico-economic analysis of a neurosurgery department at a university hospital]. / Analyse médico-économique d'un service de neurochirurgie en centre hospitalier et universitaire.

OBJECTIVE: Economic and societal constraints require to take into account the economic dimension and medical performance of hospital departments. We carried out a self-assessment study, which we thought could be useful to share with the neurosurgical community. MATERIAL AND METHODS: Care and research activities were assessed from 2009 to 2013. We used institutional and assessment-body parameters in order to describe activities and perform a financial evaluation. It was a retrospective descriptive study based on the guidelines of the DHOS/O4 circular No. 2007/390 of October 29, 2007. RESULTS: The average annual, analytic income statement was +1.39 millions euros, for 63 beds with a 92% occupancy rate, including 6.7 full-time equivalent neurosurgeons (and assistants), for 2553 patients and 1975 surgeries. The average mortality rate was 2.74%. The annual mean length of stay was 6.82 days. Per year, on average 15.6% of patients were admitted in emergency and 76.9% returned home. The annual, act-related-pricing and publication-related incomes represented 77% and 0.6%, respectively of the total funding. Difficulties to find downstream beds for the most severe patients induced 1401 "waiting days" in 2012. CONCLUSION: Medico-economic analysis of a neurosurgery department at a university hospital was useful in order to take into account the care, teaching and research activities, as well as its related financial value.

Electrical modulation of neuronal networks in brain-injured patients with disorders of consciousness: a systematic review.

Six clinical studies of chronic electrical modulation of deep brain circuits published between 1968 and 2010 have reported effects in 55 vegetative or minimally conscious patients. The rationale stimulation was to activate the cortex through the reticular-thalamic complex, comprising the tegmental ascending reticular activating system and its thalamic targets. The most frequent intended target was the central intralaminar zone and adjacent nuclei. Hassler et al. also proposed to modulate the pallidum as part of the arousal and wakefulness system. Stimulation frequency varied from 8Hz to 250Hz. Most patients improved, although in a limited way. Schiff et al. found correlations between central thalamus stimulation and arousal and conscious behaviours. Other treatments that have offered some clinical benefit include drugs, repetitive magnetic transcranial stimulation, median nerve stimulation, stimulation of dorsal column of the upper cervical spinal cord, and stimulation of the fronto-parietal cortex. No one treatment has emerged as a gold standard for practice, which is why clinical trials are still on-going. Further clinical studies are needed to decipher the altered dynamics of neuronal network circuits in patients suffering from severe disorders of consciousness as a step towards novel therapeutic strategies.