Laurent Gergelé

Background Measuring reliable intracranial pressure (ICP) is critical for patients with acute brain injuries. The aim of this study was to evaluate zero drift of the intraparenchymal strain gauge Pressio transducer (Sophysa, Orsay, France) in clinical conditions. Methods A prospective observational multicenter study was conducted in four French intensive care units of university hospitals. Patients with acute brain injuries were included if they needed ICP measurement using the Pressio transducer. The zero drift was measured at the explantation of the sensor. ICP-related adverse events were also collected. Results Between January 1, 2018, and March 31, 2020, 235 patients were included in this study for a monitoring time of 2,180 days. The zero drift assessment was determined in 223 transducers (95%). The median duration of ICP monitoring was 8 days (interquartile range [IQR] 4 to 13 days). The median zero drift was 1 mm Hg (IQR 1 to 3 mm Hg), and a weak correlation was observed between the duration of ICP monitoring and zero drift (ρ = 0.141; P = 0.0357), which lacks clinical significance. Zero drifts higher than 5 mm Hg were found in 10% of transducers. Four patients (1.8%) had ICP-related hematomas, with no clinical impact, and none had ICP-related brain infection. Failures or technical dysfunctions of the monitoring were found in six patients (2.6%). Conclusions The Pressio catheter from the Sophysa system exhibited a minor zero drift after a median monitoring period of 8 days. The transducer’s precision was comparable to that of other ICP devices using strain gauge technology.

Objective Measuring reliable intracranial pressure (ICP) is critical for patients with acute brain injuries. The aim of this study was to evaluate zero-drift of the intra-parenchymal strain gauge Pressio transducer (Sophysa, Orsay, France) in clinical conditions.Methods A prospective, observational multicentre study was conducted in 4 French intensive care units (ICU) of university hospitals. Patients with acute brain injuries were included if they needed ICP measurement using the Pressio transducer. The zero drift was measured at explanation of the sensor. ICP-related adverse events were also collected.Results Between 01/01/2018 and 31/03/2020, 235 patients were included in this study for a monitoring time of 2180 days. The zero-drift assessment was determined in 223 transducers (95%). The median duration of ICP monitoring was 8 days (interquartile [IQR] 4 to 13 days). The median zero drift was 1 mmHg (IQR 1 to 3) and a weak correlation was observed between the duration of ICP monitoring and zero drift (⍴=0.141; P = 0.0357), which lacks clinical significance. Zero drifts higher than 5 mmHg were found in 10% of transducers. Four patients (1.8%) had ICP-related hematomas, with no clinical impact, and none had ICP-related brain infection. Failures or technical dysfunctions of the monitoring were found in 6 patients (2.6%).Conclusion The Pressio catheter from the Sophysa system exhibited a minor zero drift after a median monitoring period of 8 days. This transducer's performance was comparable to that of other intracranial pressure devices utilizing strain gauge technology.

Real-time monitoring of intracranial pressure (ICP) is a routine part of neurocritical care in the management of brain injury. While mainly used to detect episodes of intracranial hypertension, the ICP signal is also indicative of the volume-pressure relationship within the cerebrospinal system, often referred to as intracranial compliance (ICC). Several ICP signal descriptors have been proposed in the literature as surrogates of ICC, but the possibilities of combining these are still unexplored. In the present study, a rapid ICC assessment consisting of a 30-degree postural shift was performed on a cohort of 54 brain-injured patients. 73 ICP signal features were calculated over the 20 minutes prior to the ICC test. After a selection step, different combinations of these features were provided as inputs to classification models. The goal was to predict the level of induced ICP elevation, which was categorized into three classes: less than 7 mmHg (“good ICC”), between 7 and 10 mmHg (“medium ICC”), and more than 10 mmHg (“poor ICC”). A logistic regression model fed with a combination of 5 ICP signal features discriminated the “poor ICC” class with an area under the receiving operator curve (AUROC) of 0.80 (95%-CI: [0.73—0.87]). The overall one-versus-one classification task was achieved with an averaged AUROC of 0.72 (95%-CI: [0.61—0.83]). Adding more features to the input set and/or using nonlinear machine learning algorithms did not significantly improve classification performance. This study highlights the potential value of analyzing the ICP signal independently to extract information about ICC status. At the patient’s bedside, such univariate signal analysis could be implemented without dependence on a specific setup.

The intracranial pressure (ICP) signal, as monitored on patients in intensive care units, contains pulses of cardiac origin, where P1 and P2 subpeaks can often be observed. When calculable, the ratio of their relative amplitudes is an indicator of the patient’s cerebral compliance. This characterization is particularly informative for the overall state of the cerebrospinal system. The aim of this study is to develop and assess the performances of a deep learning-based pipeline for P2/P1 ratio computation that only takes a raw ICP signal as an input. The output P2/P1 ratio signal can be discontinuous since P1 and P2 subpeaks are not always visible. The proposed pipeline performs four tasks, namely (i) heartbeat-induced pulse detection, (ii) pulse selection, (iii) P1 and P2 designation, and (iv) signal smoothing and outlier removal. For tasks (i) and (ii), the performance of a recurrent neural network is compared to that of a convolutional neural network. The final algorithm is evaluated on a 4344-pulse testing dataset sampled from 10 patient recordings. Pulse selection is achieved with an area under the curve of 0.90, whereas the subpeak designation algorithm identifies pulses with a P2/P1 ratio > 1 with 97.3% accuracy. Although it still needs to be evaluated on a larger number of labeled recordings, our automated P2/P1 ratio calculation framework appears to be a promising tool that can be easily embedded into bedside monitoring devices.

Prolonged disorders of consciousness (DoC) are defined by a lack of functional communication 28 days after a severe acute brain injury. Etiology, lesions’ typology and severity of DoC are essential for prognosis. So, it is important to assess these patients accurately. For this purpose, the behavioral scale CRS-R (Coma Recovery Scale - Revised) and neuroelectrophysiology examination are used. Multimodal brain MRI identifies, among other one, thalamo mesencephalic lesions which can lead to prolonged alteration of arousal. In addition, positon emission tomography (TEP) predicts poor functional outcome when cortical hypometabolism is observed in the default mode (supporting self-awareness) and in the external frontoparietal networks (supporting awareness of the environment). However, these conventional techniques can be mistaken, leading to growing interest in advanced techniques to study brain morphometry and connectivity. Amantadine and zolpidem are used to accelerate consciousness recovery but only amantadine has an authorization for temporary use in post-traumatic DOC. Their common pharmacological action supports the "mesocircuit" hypothesis linking disorder of consciousness to a reduction in thalamo-cortical and thalamo-striatal connectivity.

The number of participants in ultra-marathons is increasing. However, the data regarding the impact of this type of exercise on the cardiovascular system are contradictory. In our study, 28 ultra-trail runners were enrolled. Blood samples were collected at three time points: immediately before, immediately after, and 7 days after the ultra-marathon. Different biomarkers were measured. Immediately after the race, the blood concentrations of the different cardiac and inflammatory biomarkers increased significantly. Interestingly, some biomarkers remained high even after 7 days of recovery.

Background Therapeutic head positioning plays a role in the management of patients with acute brain injury. Although intracranial pressure (ICP) is typically lower in an upright posture than in a flat position, limited data exist concerning the effect of upright positioning on brain oxygenation and circulation. We sought to determine the impact of supine (0°) and semirecumbent (15° and 30°) postures on ICP, brain oxygenation, and brain circulation. Methods An observational cohort study was conducted between February 2012 and September 2015. Twenty-three patients with severe acute brain injury were successively observed at head elevations of 30°, 15°, and 0°. Postural-induced changes in ICP, cerebral perfusion pressure, brain tissue oxygenation pressure, and transcranial Doppler findings were simultaneously measured during three repeated experiments: 24 h after admission to the intensive care unit (exp1), 24 h later (exp2), and 96 h later (exp3). Cerebral perfusion pressure, arterial blood gases, hemoglobin content, and body temperature remained unchanged during the three experiments. Results Using linear random-slope mixed models, we found that during the early phase of acute brain injury (exp1), lowering the head posture from 30° to 15°, and then to 0°, was associated with a gradual mean ICP increase of 2.6 mm Hg (1.4–3.7 mm Hg; P < 0.001); and from 30° to 0°, an increase of 7.4 mm Hg (6.3–8.6 mm Hg; P < 0.001). Furthermore, brain tissue oxygenation pressure and mean blood flow velocity improved when the head posture was lowered from 30° to 0° by 1.2 mm Hg (0.2–2.3 mm Hg) and 4.1 cm/s (0.0–8.2 cm/s), respectively (both P < 0.05). Conclusions Changing the positioning of stable patients with acute brain injury resulted in opposite changes of ICP versus brain oxygenation and circulation. This information supports the concept of an individualized approach to head positioning that is based on the multimodal monitoring of brain parameters.

Introduction: Assessment of the individual safest minimal mean arterial pressure (MAP) during cardiac surgery remains empirical. The objective of this study was to evaluate the lower limit of autoregulation (LLA) within a short period (15 min). Methods: After developing autoregulation software (OptiMAP) incorporated into transcranial Doppler ultrasound (Waki-Atys^®, Lyon, France), we monitored the mean blood flow velocity (MV) and MAP. Thirty successive values of MV and MAP were automatically analysed to calculate the correlation (Mx) between the two parameters. We compared two methods of Mx sampling during a period of 15 min: Mx_10s = long averaging windows (one MAP/MV pair recorded every 10 s), and Mx_2s = short averaging windows (one MAP/MV pair recorded every 2 s). The LLA value calculated from the whole recording (Mx_10s) was used as the reference. Autoregulation was considered impaired at an Mx value >0.35. Results: Five patients were included in the study. The surgery lasted for 138 ± 32 min and cardiopulmonary bypass lasted for 72 ± 33 min. MAP and MV were recorded for 117 ± 24 min. MAP varied from 33 ± 10 to 92 ± 10 mmHg. LLA calculated from the whole recording (Mx_10s) was similar to LLA calculated from the 15-min recording (Mx_2s): 70 ± 2.5 versus 73 ± 3.5 mmHg. MAP remained below LLA during 48 ± 12% of the recording. During the 15-min recording, Mx_10s was not able to calculate the LLA value. Conclusion: In cases of haemodynamic instability, decreasing the Mx sampling window seems to accurately detect LLA.

Introduction: External hydrocephalus (EH) refers to impairment of extra-axial cerebrospinal fluid flow with enlargement of the subarachnoid space (SAS) and concomitant raised intracranial pressure (ICP). It is often confused with a subdural hygroma and overlooked, particularly when there is no ventricular enlargement. In this study, we aimed to describe the epidemiology of EH in a large population of adults with traumatic brain injury (TBI). Methods: This observational, retrospective cohort study was conducted in adult patients who were admitted with TBI to the Department of Clinical Neuroscience at Addenbrooke’s Hospital (Cambridge, UK) over a period of 3 years (2014–2017). Patients were included in the study if they had ICP monitoring and at least three CT scans within the first 21 days to assess SAS evolution. Patients who underwent a decompressive craniectomy were excluded. SAS was assessed individually on each CT scan by two independent investigators. ICP data were analysed with ICM+ software (Cambridge Enterprise Ltd., Cambridge, UK). Short-term and 6-month outcomes were examined. The groups of patients with and without EH were compared. Results: Of the 102 patients included in the study, 30.4% developed EH after a delay of 2.98 ± 2.4 days. The initial Glasgow Coma Scale (GCS) scores did not differ between patients with and without EH. Subarachnoid haemorrhage was found to be the main risk factor for EH. Patients with EH required a significantly longer period of mechanical ventilation (+6.9 days), were more likely to have a tracheostomy (55% versus 33%), and had a longer stay in the intensive care unit (+8.5 days). ICP was higher during the 48 h after diagnosis of EH than during the previous 48 h. EH survivors had a lower mean Glasgow Outcome Scale Extended (GOS-E) score (4.6 versus 5.9, P = 0.031) and were more likely to receive a permanent shunt for secondary hydrocephalus (17.4% versus 1.8%, odds ratio 7.1). Conclusion: In adults with TBI, EH remains insufficiently understood and probably underdiagnosed. This study showed that it is a frequent complication of TBI, with significant clinical consequences.