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Background: Intraoperative arterial hypotension (IOH) leads to increased postoperative morbidity. Norepinephrine is often use to treat IOH. The question regarding the mode of administration in either a bolus or continuous infusion remains unanswered. The aim of the present study was to describe and compare the effects on macrocirculation and microcirculation of a bolus and a continuous infusion of norepinephrine to treat IOH. Methods: We conducted a prospective observational study with adult patients who underwent neurosurgery. Patients with invasive arterial blood pressure and cardiac output (CO) monitoring were screened for inclusion. All patients underwent microcirculation monitoring by video-capillaroscopy, laser doppler, near-infrared spectroscopy technology, and tissular CO2. In case of IOH, the patient could receive either a bolus of 10 µg or a continuous infusion of 200 µg/h of norepinephrine. Time analysis for comparison between bolus and continuous infusion were at peak of MAP. Results: Thirty-five patients were included, with 41 boluses and 33 continuous infusion. Bolus and continuous infusion induced an maximal increase in mean arterial pressure of +30[20-45] and +23[12-34] %, respectively (P=0,07). For macrocirculatory parameters, continuous infusion was associated with a smaller decrease in CO and stroke volume (pConclusions: These results on macro and microcirculation enlighten the potential benefits of a continuous infusion of norepinephrine rather than a bolus to treat anaesthesia-induced hypotension. Trial registration : (NOR-PHARM: 1-17-42 Clinical Trials: NCT03454204), 05/03/2018

Purpose: Intraoperative arterial hypotension (IOH) leads to increased postoperative morbidity and mortality. Norepinephrine is often use to treat IOH. However, the question regarding the mode of administration in either a bolus or continuous infusion (CI) remains unanswered. The aim of the present study was to describe and compare the effects on macrocirculation and microcirculation of a bolus and a CI of norepinephrine to treat IOH.Methods: We conducted a prospective observational study with adult patients who underwent neurosurgery. Patients with invasive arterial blood pressure and cardiac output (CO) monitoring were screened for inclusion. All patients underwent microcirculation monitoring by video capillaroscopy, laser doppler, near-infrared spectroscopy technology, and tissue CO2. In case of IOH, the patient could receive either a bolus of 10 µg or a CI of 200 µg/h of norepinephrine.Results: Thirty-six patients were included, with 41 boluses and 33 CI.Bolus and CI induced an increase in mean arterial pressure of +30[20-45] and +23[12-34] %, respectively (P=0,07). For macrocirculatory parameters, CI was associated with a smaller decrease in CO and stroke volume (pConclusions: These results on macro- and microcirculation could reveal the need for the preferential use of a continuous infusion of norepinephrine rather than a bolus to treat anaesthesia-induced hypotension.Trial registration : (NOR-PHARM: 1-17-42 Clinical Trials: NCT03454204).

International audience; Cognitive decline (CD) is a common condition amongst elderly, affecting memory, language or thinking. Patients experiencing CD have a higher incidence rate of post-operative neurocognitive disorders 1. Moreover, for a fraction of these patients

Continuous measurement of aortic pressure and aortic flow velocity signals in the operating theatre allows us to draw velocity-pressure (Vel-Pre) loops. The global afterload angle (GALA), derived from the Vel-Pre loops, has been linked to cardiac afterload indicators. As age is the major determinant of constitutive arterial stiffness, we aimed to describe (1) the evolution of the GALA according to age in a large cohort of anesthetized patients and (2) GALA variations induced by haemodynamic interventions. We included patients for whom continuous monitoring of arterial pressure and cardiac output were indicated. Fluid challenges or vasopressors were administered to treat intra-operative hypotension. The primary endpoint was the comparison of the GALA values between young and old patients. The secondary endpoint was the difference in the GALA values before and after haemodynamic interventions. We included 133 anaesthetized patients: 66 old and 67 young patients. At baseline, the GALA was higher in the old patients than in young patients (38 ± 6 vs. 25 ± 4 degrees; p < 0.001). The GALA was positively associated with age (p < 0.001), but the mean arterial pressure (MAP) and cardiac output were not. The GALA did not change after volume expansion, regardless of the fluid response, but it did increase after vasopressor administration. Furthermore, while a vasopressor bolus led to a similar increase in MAP, phenylephrine induced a more substantial increase in the GALA than noradrenaline (+ 12 ± 5° vs. + 8 ± 5°; p = 0.01). In non-cardiac surgery, the GALA seems to be associated with both intrinsic rigidity (reflected by age) and pharmacologically induced vasoconstriction changes (by vasopressors). In addition, the GALA can discriminate the differential effects of phenylephrine and noradrenaline. These results should be confirmed in a prospective, ideally randomized, trial.

Multi-beat analysis (MBA) of the radial arterial pressure (AP) waveform is a new method that may improve cardiac output (CO) estimation via modelling of the confounding arterial wave reflection. We evaluated the precision and accuracy using the trending ability of the MBA method to estimate absolute CO and variations (ΔCO) during hemodynamic challenges. We reviewed the hemodynamic challenges (fluid challenge or vasopressors) performed when intra-operative hypotension occurred during non-cardiac surgery. The CO was calculated offline using transesophageal Doppler (TED) waveform (COTED) or via application of the MBA algorithm onto the AP waveform (COMBA) before and after hemodynamic challenges. We evaluated the precision and the accuracy according to the Bland & Altman method. We also assessed the trending ability of the MBA by evaluating the percentage of concordance with 15% exclusion zone between ΔCOMBA and ΔCOTED. A non-inferiority margin was set at 87.5%. Among the 58 patients included, 23 (40%) received at least 1 fluid challenge, and 46 (81%) received at least 1 bolus of vasopressors. Before treatment, the COTED was 5.3 (IQR [4.1–8.1]) l min−1, and the COMBA was 4.1 (IQR [3–5.4]) l min−1. The agreement between COTED and COMBA was poor with a 70% percentage error. The bias and lower and upper limits of agreement between COTED and COMBA were 0.9 (CI95 = 0.82 to 1.07) l min−1, −2.8 (CI95 = −2.71 to−2.96) l min−1 and 4.7 (CI95 = 4.61 to 4.86) l min−1, respectively. After hemodynamic challenge, the percentage of concordance (PC) with 15% exclusion zone for ΔCO was 93 (CI97.5 = 90 to 97)%. In this retrospective offline analysis, the accuracy, limits of agreements and percentage error between TED and MBA for the absolute estimation of CO were poor, but the MBA could adequately track induced CO variations measured by TED. The MBA needs further evaluation in prospective studies to confirm those results in clinical practice conditions.

BackgroundEEG is a common tool for monitoring anaesthetic depth but is rarely reused at large for biomedical research. This study sets out to explore repurposing of EEG during anaesthesia to learn biomarkers of brain ageing in the absence of consciousness.MethodsWe focused on brain age estimation as an example. Using machine learning, we reanalysed 4-electrodes EEG of 323 patients under propofol and sevoflurane. We included spatio-spectral features from stable anaesthesia for EEG-based age prediction applying recently published reference methods. Anaesthesia was considered stable when 95% of the total power was below a frequency between 8Hz and 13Hz.ResultsWe considered moderate-risk patients (ASA ConclusionsEEG from general anaesthesia may enable state-of-the-art brain age prediction. Yet, differences between anaesthetic drugs can impact the effectiveness of repurposing EEG from anaesthesia. To unleash the dormant potential of repurposing EEG-monitoring for clinical and health research, in the absence of consciousness, collecting larger datasets with precisely documented drug dosage will be key enabling factors.

INTRODUCTION During anesthesia, decreases in mean arterial pressure (MAP) are common but the impact on possible cerebral hypoperfusion remains a matter of debate. We evaluated cerebral perfusion in patients with or without cardiovascular comorbidities (Hi-risk vs Lo-risk) during induction of general anesthesia and during hypotensive episodes. METHODS Patients scheduled for neuroradiology procedure using standardized target-controlled Propofol-Remifentanil infusion were prospectively included. Monitoring included Transcranial Doppler (TCD) measuring mean blood velocity of the middle cerebral artery (Vm), Bispectral Index with burst suppression ratio (SR) and cerebral Near-Infrared Spectroscopy (NIRS). Hypotensive episodes were treated with a 10 µg bolus of Norepinephrine. RESULTS Eighty-one patients were included, 37 Hi-risk and 44 Lo-risk. During induction of anesthesia, MAP and Vm decreased in all patients, with greater changes observed in Hi-risk patients compared to Lo-risk patients (-34 [38-29]% vs -17 [25-8]%, P

Hypotension during general anesthesia is associated with poor outcome. Continuous monitoring of mean blood pressure (MAP) during anesthesia is useful and needs to be reliable and minimally invasive. Conventional cuff measurements can lead to delays due to its discontinuous nature. It has been shown that there is a relationship between MAP and photoplethysmography (PPG) parameters like the dicrotic notch and perfusion index (PI). The objective of the study was to continuously estimate MAP from PPG. Pulse wave analysis based on PPG was implemented using either notch relative amplitude (MAPNRA), notch absolute amplitude (MAPNAA) or PI (MAPPI) to estimate MAP from PPG waveform features during general anesthesia. Estimated MAP values were compared to brachial cuff MAP (MAPcuff) and to radial invasive MAP (MAPinv). Forty-six patients were analyzed for a total of 235 h. Compared to MAPcuff, mean bias and limits of agreement were 1 mmHg (− 26 to +29), − 1 mmHg (− 10 to +8) and − 3 mmHg (− 21 to +13) for MAPNRA, MAPNAA and MAPPI respectively. Compared to MAPinv, mean absolute error (MAE) was 20 mmHg [10 to 39], 11 mmHg [5 to 18] and 16 mmHg [9 to 24] for MAP derived from MAPNRA, MAPNAA and MAPPI respectively. When calibrated every 5 min, MAPNAA showed a MAE of 6 mmHg [5 to 9]. MAPNAA provides the best estimates with respect to brachial cuff MAP and invasive MAP. Regular calibration allows to reduce drift over time. Beat to beat estimation of MAP during general anesthesia from the PPG appears possible with an acceptable average error.

Establishing neurological prognoses in traumatic brain injury (TBI) patients remains challenging. To help physicians in the early management of severe TBI, we have designed a visual score (ICEBERG score) including multimodal monitoring and treatment-related criteria. We evaluated the ICEBERG scores among patients with severe TBI to predict the 28-day mortality and long-term disability (Extended Glasgow Outcome Scale score at 3 years). In addition, we made a preliminary assessment of the nurses and doctors on the uptake and reception to the use of the ICEBERG visual tool.This study was part of a larger prospective cohort study of 207 patients with severe TBI in the Parisian region (PariS-TBI study). The ICEBERG score included six variables from multimodal monitoring and treatment-related criteria: cerebral perfusion pressure, intracranial pressure, body temperature, sedation depth, arterial partial pressure of CO 2 , and blood osmolarity. The primary outcome measures included the ICEBERG score and its relationship with hospital mortality and Extended Glasgow Outcome Score.The hospital mortality was 21% (45/207). The ICEBERG score baseline value and changes during the 72nd first hours were more strongly associated with TBI prognosis than the ICEBERG parameters measured individually. Interestingly, when the clinical and computed tomography parameters at admission were combined with the ICEBERG score at 48 hours using a multimodal approach, the predictive value was significantly increased (area under the curve = 0.92). Furthermore, comparing the ICEBERG visual representation with the traditional numerical readout revealed that changes in patient vitals were more promptly detected using ICEBERG representation ( p0.05).The ICEBERG score could represent a simple and effective method to describe severity in TBI patients, where a high score is associated with increased mortality and disability. In addition, ICEBERG representation could enhance the recognition of unmet therapeutic goals and dynamic evolution of the patient's condition. These preliminary results must be confirmed in a prospective manner.Diagnostic Tests or Criteria; Level III.

International audience; The photoacoustic effect in liquids, generated by metal nanoparticles excited with short laser pulses, offers high contrast imaging and promising medical treatment techniques. Understanding the role of the thermal boundary resistance (TBR) and the laser pulse duration in the generation mechanism of acoustic waves is essential to implement efficient photoacoustic nanotransducers. This work theoretically investigates, for the paradigmatic case of water-immersed gold nanocylinders, the role of the TBR and laser pulse duration in the competition between the launching mechanisms: the thermophone and the mechanophone. In the thermophone, the nanoparticle acts as a nanoheater and the wave is launched by water thermal expansion. In the mechanophone, the nanoparticle directly acts as a nanopiston. Specifically, for a gold–water interface, the thermophone prevails under ns light pulse irradiation, while the mechanophone dominates shortening the pulse to the 10 ps regime. For a graphene-functionalized gold–water interface, instead, the mechanophone dominates over the entire range of explored laser pulse durations. The results point to high-TBR, liquid-immersed nanoparticles as potentially efficient photoacoustic nanogenerators, with the advantage of keeping the liquid environment temperature unaltered.

Background and purposeCone-beam CT angiography (CB-CTA) provides a three-dimensional spatial resolution which is, so far, unmatched in clinical practice compared with other conventional techniques such as two-dimensional digital subtracted angiography. We aimed to assess the distribution of symptomatic cerebral vasospasm following aneurysmal subarachnoid hemorrhage (aSAH) using CB-CTA.Methods30 consecutive patients with aSAH undergoing vasospasm percutaneous balloon angioplasty (PBA) were recruited and underwent CB-CTA in this single-center prospective cohort series. Intracranial arteries were systematically analyzed by two independent observers from the large trunks to the distal cortical branches and perforators using a high-resolution reconstruction protocol. Intermediate and severe cerebral vasospasm was defined as 30–50% and >50% narrowing in the diameter of the vessel, respectively.Results35 arterial cervical artery territories were analyzed, of which 80% were associated with clinical or radiological signs of delayed cerebral ischemia. The median spatial resolution was 150 µm (range 100–250 µm). Intermediate or severe vasospasm was observed in the proximal (86%, 95% CI 74% to 97%), middle (89%, 95% CI 78% to 99%), and distal (60%, 95% CI 44% to 76%) segments of the large trunks, as well as the cortical branches (11%, 95% CI 1% to 22%). No vasospasm was observed in basal ganglia or cortical perforators, or in arteries smaller than 900 µm. Vasospasm was more severe in middle or distal segments compared with proximal segments in 43% (95% CI 26% to 59%) of cases.ConclusionsOur study demonstrated that symptomatic cerebral vasospasm following aSAH did not involve arteries smaller than 900 µm, and frequently predominated in middle or distal segments. These results offer new insights into the potential management options for vasospasm using PBA.

The physiology of venous and tissue CO2 monitoring has a long and well-established physiological background, leading to the technological development of different tissue capnometric devices, such as transcutaneous capnometry monitoring (TCM). To outline briefly, measuring transcutaneous PCO2 (tcPCO2) depends on at least three main phenomena: (I) the production of CO2 by tissues (VCO2), (II) the removal of CO2 from the tissues by perfusion (wash-out phenomenon), and (III) the reference value of CO2 at tissue inlet represented by arterial CO2 content (approximated by arterial PCO2, or artPCO2). For this reason, there are, at present, roughly two clinical uses for tcPCO2 measurement: a respiratory approach where tcPCO2 is likely to estimate and non-invasively track artPCO2; and a hemodynamic under-estimate use where tcPCO2 can reflect tissue perfusion, summarized by a so-called "tc-art PCO2 gap". Recent research shows that these two uses are not incompatible and could be combined. The spectrum of indications and validation studies in ICUs is summarized in this review to give a survey of the potential applications of TCM in critically ill patients, focusing mainly on its potential (micro)circulatory monitoring contribution. We strongly believe that the greatest benefit of measuring tcPCO2 is not to only to estimate artPCO2, but also to quantify the gap between these two values, which can then help clinicians continuously and noninvasively assess both respiratory and hemodynamic failures in critically ill patients.

Resume La craniotomie en condition eveillee avec electrostimulation corticale permet d’operer des lesions localisees en zone fonctionnelle : elle consiste a reperer et epargner les structures cerebrales eloquentes tout en maximisant la resection des lesions. La chirurgie se deroule en trois phases successives : une phase d’ouverture, une phase de travail pendant laquelle le patient doit etre parfaitement eveille afin de realiser une evaluation neurologique fine, et enfin, une phase de fermeture. L’anesthesie pour une craniotomie en condition eveillee constitue un defi unique. La selection des patients doit etre rigoureuse. L’anesthesie locale du scalp est systematique. Les phases d’ouverture et de fermeture peuvent etre gerees de differentes facons qui presentent des avantages et des inconvenients propres : anesthesie generale avec ventilation mecanique, sedation en ventilation spontanee, absence d’anesthesiques generaux, hypnose. Il n’existe pas dans la litterature d’etude permettant d’etablir clairement la superiorite d’une technique par rapport a une autre.

Lateral venous sinus stenoses have been associated with idiopathic intracranial hypertension and venous pulsatile tinnitus. Venous pressure measurement is traditionally performed to assess the indications for stenting in patients with idiopathic intracranial hypertension. However, its reliability has recently been questioned by many authors. The dual-sensor guidewire was first developed for advanced physiological assessment of fractional and coronary flow reserves in coronary artery stenoses. It allows measurement of both venous pressure and blood flow velocities. The authors used this device in 14 consecutively treated patients to explore for symptomatic lateral sinus stenosis. They found that venous blood flow was significantly accelerated inside the stenotic lesion. This acceleration, as well as the pulsatile tinnitus, resolved in all patients following stent placement. According to the authors’ results, this guidewire can be helpful for establishing an indication for stenting in patients with pulsatile tinnitus and idiopathic intracranial hypertension.

Transcranial Doppler (TCD) of the middle cerebral artery (MCA) enables the measurement of the mean blood velocity (MCAVm) and the estimation of the cerebral blood flow (CBF), provided that no significant changes occur in the MCA diameter (MCADiam). Previous studies described a decrease in the MCAVm associated with the induction of total intravenous anesthesia (TIVA) by propofol and remifentanil. This decrease in blood velocity might be interpreted as a decrease in the CBF only where the MCADiam is not modified across TCD examinations. In this observational study, we measured the MCADiam of 24 subjects (almost exclusively females) on digital subtraction angiography under awake and TIVA conditions. Across the two phases, we observed a decrease in the mean arterial blood pressure (from 84 ± 9 to 71 ± 6 mmHg; p

Short title: Clinical Usefulness of Perfusion Index; International audience; Photoplethysmography (PPG) has been extensively used for pulse oximetry monitoring in anaesthesia, perioperative and intensive care. However, some components of PPG signal have been employed for other purposes, such as non-invasive haemodynamic monitoring. Perfusion index (PI) is derived from PPG signal and represents the ratio of pulsatile on non-pulsatile light absorbance or reflectance of the PPG signal. PI determinants are complex and interlinked, involving and reflecting the interaction between peripheral and central haemodynamic characteristics, such as vascular tone and stroke volume. Recently, several studies have shed light on the interesting performances of this variable, especially assessing regional or neuraxial block success, and haemodynamic monitoring in anaesthesia, perioperative and intensive care. Nevertheless, no review has yet been published concerning the interest of PI in these fields. In this narrative review will be exposed first the physiological and pathophysiological determinants of PI, and then the mean to measure this value as well as its potential limitations. In the second part, the existing data concerning usefulness of PI in different clinical settings such as operating theatres, intensive care units and emergency departments will be presented and discussed. Finally, the perspectives concerning the use of PI and mentioned aspects that should be explored regarding this tool will be underlined.

International audience; Highly symmetrical gold nanocages can be produced with a controllable number of circular windows of either 2, 3, 4, 6 or 12 via an original fabrication route. The synthetic pathway includes three main stages: the synthesis of silica/polystyrene multipod templates, the regioselective seeded growth of a gold shell on the unmasked part of the silica surface and the development of gold nanocages by dissolving/etching the templates. Electron microscopy and tomography provide evidence of the symmetrical features of the as-obtained nanostructures. The optical properties of nanocages with 4 and 12 windows were measured at the single particle level by spatial modulation spectroscopy and correlated with numerical simulations based on finite-element modeling. The new multi-step synthesis approach reported here also allows the synthesis of rattle-like nanostructures through filling of the nanocages with a guest nano-object. With the potential to adjust the chemical composition, size and geometry of both the guest particle and the host cage, it opens new routes towards the fabrication of hollow nanostructures of high interest for a variety of applications including sensing devices, catalytic reactors and biomedicine. New concepts We demonstrate a new concept for making hollow nanoscale structures which are central to the advances in many current and emerging areas of technology. Nanocages are hollow and porous nanostructures. The ones made of metal are needed for optics, catalysis, biomedicine, and sensing. But, they are difficult to make. In particular, it is difficult to yield precise nanoscale control of the porosity as well as the composition. We address this challenge by combining inorganic colloidal synthesis and metal deposition on biphasic sacrificial templates. The single-particle spectroscopy and simulation confirm that our approach affords tight control over the morphology and porosity at the nanoscale. Previous approaches to making metal nanocages rely on galvanic replacement reactions and siteselective deposition. They offer control over morphology, but limited control over composition, porosity and scaleup. Our approach provides a simple and general strategy to circumvent these issues. It can be applied to a wide range of materials, and with further developement to any nanorattle-like nanostructures.

International audience; The sudden absorption of light by a metal nanoparticle launches a series of relaxation processes (internal thermalization, acoustic vibrations, and cooling) which induce a transient modification of its optical response. In this work, the transient optical response associated with the internal thermalization of a single gold nanodisk (occurring on a few picoseconds time scale) was quantitatively investigated by time-resolved spectroscopy experiments, and the measured signals were compared with a model accounting for the effects of both electron and ionic lattice heating. We show that experimental time-resolved signals at delays posterior to nanodisk excitation and electron gas thermalization can be simply interpreted as a combination of electron and lattice temperature evolutions, with probe wavelength-dependent weights. This demonstrates the possibility to selectively probe the electronic or lattice dynamics, through the choice of specific probe wavelengths. Additionally, the time-dependent spectral shape of transient extinction cross-section changes is shown to be successively dominated by the effects of electron and lattice heating, which present distinct spectral signatures.

International audience; Single-particle optical spectroscopy methods have enabled quantitative investigations of the optical, electronic, and vibrational responses of nano-objects in the recent years. In this work, single-particle pump–probe optical spectroscopy was exploited to investigate the cooling dynamics of individual gold nanodisks supported on a sapphire substrate. The measured time-resolved signals are shown to directly reflect the temporal evolution of the nanodisk temperature following its sudden excitation. The single-particle character of the experiments enables a quantitative analysis of the amplitudes of the measured time-resolved signals, allowing to rationalize their large probe wavelength dependence. The measured cooling kinetics mainly depends on the nanodisk thickness and to a much lesser extent on the diameter, in agreement with numerical simulations based on Fourier law of heat diffusion, also accounting for the presence of a thermal resistance at the interface between the nanodisks and their substrate. For the explored diameter range (60–190 nm), the nanodisk cooling rate is limited by heat transfer at the gold–sapphire interface, whose thermal conductance can be estimated for each investigated nanodisk.

International audience; Background: Awake surgery has become a key treatment of diffuse low-grade gliomas (DLGG) and is divided in three main phases: opening, tumor resection - during which the patient needs to be fully awake - and closure. The anesthetic management of awake neurosurgery is a challenge, and there are currently no guidelines.Objective: The objective of the survey was to explore differences and commonalities regarding the anesthetic management of awake DLGG surgery within the European Low-Grade Glioma Network (ELGGN) centers.Methods: A form that contained 14 questions about the anesthetic management was sent to 28 centers in May 2015.Results: Twenty centers responded. During the opening and closing non-awake periods, 56% of teams chose general anesthesia with mechanical ventilation for at least one period (asleep-awake-asleep, SAS protocol), and 44% monitored anesthesia care including sedation without mechanical ventilation (MAC protocol). In case of SAS, all the teams chose intravenous anesthesia, 82% used laryngeal mask instead of endotracheal intubation during the opening sequence, and 71% during closure. Local and regional anesthesia was practiced by all the teams. The most frequently reported cause of pain was dural and cerebral vessels manipulation (77%). Pain management was mostly based on paracetamol (70%) and remifentanil (55%).Conclusion: Our survey showed that there was an equivalent proportion of centers using SAS or MAC protocols in the anesthetic management of awake surgery in ELGGN centers. The advantages and disadvantages of each anesthesia protocol were reviewed.

BACKGROUND Global afterload angle (GALA) is a parameter derived from velocity-pressure loop (VP Loop), for continuous assessment of cardiac afterload in the operating room. It has been validated with invasive measure of central pressure. The aim of this study was to evaluate the feasibility of noninvasive VP Loop obtained with central pressure measured with two different noninvasive tonometers. METHODS A prospective, observational, monocentric study was conducted in 51 patients under general anesthesia. Invasive central pressure (cPINV) was measured with a fulfilled intravascular catheter, and noninvasive central pressure signals were obtained with two applanation tonometry devices: radial artery tonometry (cPSHYG: Sphygmocor tonometer) and carotid tonometry (cPCOMP: Complior tonometer). Three VP Loops were built: VP LoopINV, VP LoopSPHYG and VP LoopCOMP. Patients were separated according to cardiovascular risk factors. RESULTS In the 51 patients under general anesthesia, cPSHYG was adequately obtained in 48 patients (89%) but, compared to cPINV, SBP was underestimated (-4 ± 6 mmHg, P < 0.0001), augmentation index (AIXSPHYG) and a GALASPHYG were overestimated (+13 ± 19%, P = 0.0077 and +4 ± 8°, P = 0.0024, respectively) with large limit of agreement (LOA) (-21 to 47% and -13 to 21° for AIXSPHYG and GALASPHYG, respectively). With the Complior, the failure rate of measurement for cPCOMP was 41%. SBP was similar (3 ± 17 mmHg, P = 0.32), AIXCOMP was underestimated (-11 ± 19%, P = 0.0046) and GALACOMP was similar but with large LOA (-50 to 26% and -20 to 18° for AIXCOMP and GALACOMP, respectively). CONCLUSION In anesthetized patient, the reliability of noninvasive central pressure monitoring by tonometry seems too limited to monitor cardiac afterload with VP Loop.

Continuous measurement of aortic pressure and aortic flow velocity signals in the operating theatre allows us to draw velocity-pressure (Vel-Pre) loops. The global afterload angle (GALA), derived from the Vel-Pre loops, has been linked to cardiac afterload indicators. As age is the major determinant of constitutive arterial stiffness, we aimed to describe (1) the evolution of the GALA according to age in a large cohort of anesthetized patients and (2) GALA variations induced by haemodynamic interventions.We included patients for whom continuous monitoring of arterial pressure and cardiac output were indicated. Fluid challenges or vasopressors were administered to treat intra-operative hypotension. The primary endpoint was the comparison of the GALA values between young and old patients. The secondary endpoint was the difference in the GALA values before and after haemodynamic interventions.We included 133 anaesthetized patients: 66 old and 67 young patients. At baseline, the GALA was higher in the old patients than in young patients (38 ± 6 vs. 25 ± 4 degrees; p0.001). The GALA was positively associated with age (p0.001), but the mean arterial pressure (MAP) and cardiac output were not. The GALA did not change after volume expansion, regardless of the fluid response, but it did increase after vasopressor administration. Furthermore, while a vasopressor bolus led to a similar increase in MAP, phenylephrine induced a more substantial increase in the GALA than noradrenaline (+ 12 ± 5° vs. + 8 ± 5°; p = 0.01).In non-cardiac surgery, the GALA seems to be associated with both intrinsic rigidity (reflected by age) and pharmacologically induced vasoconstriction changes (by vasopressors). In addition, the GALA can discriminate the differential effects of phenylephrine and noradrenaline. These results should be confirmed in a prospective, ideally randomized, trial.

International audience; Time-resolved thermoplasmonics is emerging as the go-to technique for nanoscale thermal metrology. In this context, connecting the ultrafast optical response of nanoobjects to the correct thermal pathways is of paramount importance. We developed full thermo-optical models relating transient spectroscopy measurements, performed on metal nanoobjects in dielectric environments, to the overall system thermal dynamics. The models are applicable to small spherical nanoparticles embedded in a homogeneous matrix, following an analytical approach, and are expanded to include the cases of arbitrarily complex geometries and sizes relying on the finite-element method. These approaches are then exploited to rationalize several observations made in the context of previous time-resolved thermo-optical studies at the nanoscale. The present tools open the path for accurate retrieval of thermal parameters, notably the Kapitza resistance and the local environment thermal conductivity, from experiments. They also allow identifying the optimal parameters for selectively probing thermal dynamics of either a nanoobject or its nanoscale environment.

Objectives To evaluate the interchangeability of oxygen consumption variations measured with the Fick equation (ΔVO2Fick) and indirect calorimetry (ΔVO2Haldane) in critically ill burns patients. Methods Prospective observational single-center study conducted in a university hospital. Twenty-two consecutive burns patients with circulatory insufficiency and hyperlactatemia (>2 mmol/L) who required a fluid challenge (FC) were included. All patients had cardiac output monitoring (transpulmonary thermodilution technique) and were ventilated and sedated. Simultaneous measurements of VO2Fick and VO2Haldane were performed before and immediately after the FC, at rest, and in hemodynamic conditions stabilized for at least 1 h. VO2Fick and VO2Haldane were measured, respectively, with the standard formulae (using arterial and central venous saturation measured with a blood gas analyzer) and with a metabolic monitor. Results Forty-four paired measurements of VO2 were obtained. At each timepoint, the median (interquartile range, 25-75) VO2Haldane values were significantly higher than the median VO2Fick values (126 (103-192) vs. 90 (66-149) mL O2/min/m (P = 0.004) before FC and 129 (105-189) vs. 80 (54-119) mL O2/min/m (P = 0.001) after FC). Correlation between the ΔVO2Fick and the ΔVO2Haldane (%) measurements was poor, with an r = 0.06, (P = 0.77). The mean bias was 8.6% [limits of agreement (LOA): -75.7%, 92.9%]. Conclusions Analysis of agreement showed poor concordance for the ΔVO2Haldane and the ΔVO2Fick (%) with a low mean bias but large and clinically unacceptable LOA. ΔVO2Haldane and ΔVO2Fick (%) are not interchangeable in these conditions.

Background Lateral sinus stenosis is a little-known cause for pulsatile tinnitus (PT). In several small series, stenting has been described as an effective treatment for disabling PT linked with this type of stenosis. Objectives To describe the clinical, radiological, and manometric characteristics of patients treated for disabling PT by lateral sinus stenosis. Assessment of the efficacy of stenting for this indication. Methods Retrospective study of patients treated for isolated PT by stenting of a lateral sinus stenosis in our institution, between 2009 and 2015. Results Fourteen patients were included in our study. All of them were women. The median age at the onset of symptoms was 39.0 (21.0) years. The median body mass index was 28.5 (7.0) kg/m 2 . Stenting of the lateral sinus led to the disappearance of PT without recurrence in 13 patients. In one patient, stenting did not modify the noise. In this case, another cause of PT was diagnosed after stent placement. Conclusion Lateral sinus stenosis is a curable cause of venous PT. Other causes of PT must be ruled out before an endovascular treatment is undertaken, due to the frequent asymptomatic nature of Pacchioni granulations in the lateral sinus. Treatment by stenting is effective in all cases, provided that stenosis underlies the PT.

Background: Over the past decade, stenting of lateral sinus stenosis has been used to treat idiopathic intracranial hypertension. Two types of stenoses have been identified: extrinsic and intrinsic. Objective: The aim of this study was to report the results of our use of this procedure to treat patients with extrinsic or intrinsic stenoses in idiopathic intracranial hypertension. Methods: We retrospectively studied clinical, radiological, and manometric data from patients with idiopathic intracranial hypertension who were treated at our institution between January 2009 and January 2015 by stenting of the lateral sinus. Results: Data were studied from 19 women and 2 men. Average body mass index was 29 kg/m 2 , and the median age at stenting was 33 years. Patients with extrinsic stenoses were younger than those with intrinsic stenoses. Transstenotic gradients measured with patients under general anesthesia were lower than those measured with patients under local anesthesia. In all cases, stenting was effective for papilledema and pulsatile tinnitus. Seventeen patients reporting headaches found that they disappeared completely after stenting. Two complications without long-term effects were reported. Conclusion: Irrespective of the type of stenosis, stenting of lateral sinus stenoses is an effective treatment for intracranial hypertension symptoms. At our institution, this treatment has replaced draining of cerebrospinal fluid when treatment with acetazolamide has proved to be ineffective.

La CID50 fait partie des commissions interdisciplinaires du Comité national de la recherche scientifique. Son rôle est transdisciplinaire. Elle travaille en coordination avec la direction générale déléguée à la science du CNRS et en relation avec la totalité des instituts du CNRS. Son rôle est de mener l'évaluation des chercheurs dont une part significative de l'activité est consacrée à la « gestion de la recherche ». Le présent rapport de conjoncture dresse un constat sur la diversité et l'importance des activités couvertes par ce vocable. Il vise également à mettre en évidence des évolutions dans ces activités.

International audience; The plasmonic and vibrational properties of single gold nanodisks patterned on a sapphire substrate are investigated via spatial modulation and pump–probe optical spectroscopies. The features of the measured extinction spectra and time-resolved signals are highly sensitive to minute deviations of the nanodisk morphology from a perfectly cylindrical one. An elliptical nanodisk section, as compared to a circular one, lifts the degeneracy of the two nanodisk in-plane dipolar surface plasmon resonances, which can be selectively excited by controlling the polarization of the incident light. This splitting effect, whose amplitude increases with nanodisk ellipticity, correlates with the detection of additional vibrational modes in the context of time-resolved spectroscopy. Analysis of the measurements is performed through the combination of optical and acoustic numerical models. This allows us first to estimate the dimensions of the investigated nanodisks from their plasmonic response and then to compare the measured and computed frequencies of their detectable vibrational modes, which are found to be in excellent agreement. This study demonstrates that single-particle optical spectroscopies are able to provide access to fine morphological characteristics, representing in this case a valuable alternative to traditional techniques aimed at postfabrication inspection of subwavelength nanodevice morphology.

Hypotension during general anesthesia is associated with poor outcome. Continuous monitoring of mean blood pressure (MAP) during anesthesia is useful and needs to be reliable and minimally invasive. Conventional cuff measurements can lead to delays due to its discontinuous nature. It has been shown that there is a relationship between MAP and photoplethysmography (PPG) parameters like the dicrotic notch and perfusion index (PI). The objective of the study was to continuously estimate MAP from PPG. Pulse wave analysis based on PPG was implemented using either notch relative amplitude (MAP

The physiology of venous and tissue CO(2) monitoring has a long and well-established physiological background, leading to the technological development of different tissue capnometric devices, such as transcutaneous capnometry monitoring (TCM). To outline briefly, measuring transcutaneous PCO(2) (tcPCO(2)) depends on at least three main phenomena: (I) the production of CO(2) by tissues (VCO(2)), (II) the removal of CO(2) from the tissues by perfusion (wash-out phenomenon), and (III) the reference value of CO(2) at tissue inlet represented by arterial CO(2) content (approximated by arterial PCO(2), or artPCO(2)). For this reason, there are, at present, roughly two clinical uses for tcPCO(2) measurement: a respiratory approach where tcPCO(2) is likely to estimate and non-invasively track artPCO(2); and a hemodynamic under-estimate use where tcPCO(2) can reflect tissue perfusion, summarized by a so-called “tc-art PCO(2) gap”. Recent research shows that these two uses are not incompatible and could be combined. The spectrum of indications and validation studies in ICUs is summarized in this review to give a survey of the potential applications of TCM in critically ill patients, focusing mainly on its potential (micro)circulatory monitoring contribution. We strongly believe that the greatest benefit of measuring tcPCO(2) is not to only to estimate artPCO(2), but also to quantify the gap between these two values, which can then help clinicians continuously and noninvasively assess both respiratory and hemodynamic failures in critically ill patients.

The end-systolic elastance (\(E_{\text {es}}\)) – the slope of the end-systolic pressure-volume relationship (ESPVR) at the end of ejection phase – has become a reliable indicator of myocardial functional state. The estimation of \(E_{\text {es}}\) by the original multiple-beat method is invasive, which limits its routine usage. By contrast, non-invasive single-beat estimation methods, based on the assumption of the linearity of ESPVR and the uniqueness of the normalised time-varying elastance curve \(E^N(t)\) across subjects and physiology states, have been applied in a number of clinical studies. It is however known that these two assumptions have a limited validity, as ESPVR can be approximated by a linear function only locally, and \(E^N(t)\) obtained from a multi-subject experiment includes a confidence interval around the mean function. Using datasets of 3 patients undergoing general anaesthesia (each containing aortic flow and pressure measurements at baseline and after introducing a vasopressor noradrenaline), we first study the sensitivity of two single-beat methods—by Sensaki et al. and by Chen et al.—to the uncertainty of \(E^N(t)\). Then, we propose a minimally-invasive method based on a patient-specific biophysical modelling to estimate the whole time-varying elastance curve \(E^{\text {model}}(t)\). We compare \(E^{\text {model}}_{\text {es}}\) with the two single-beat estimation methods, and the normalised varying elastance curve \(E^{N,\text {model}}(t)\) with \(E^{N}(t)\) from published physiological experiments.