Applied Sciences

Mechanical ventilators are essential to patients who become critically ill from acute respiratory distress syndrome (ARDS), and shortages have been reported due to the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We utilized cost-effective, on-demand 3D printing (3DP) technology to produce critical components for a novel ventilator multiplexer system, Vent-Lock, to split one ventilator or anesthesia gas machine between two patients. FloRest, a novel 3DP flow restrictor, provides clinicians control of tidal volumes and positive end expiratory pressure (PEEP), using the 3DP manometer adaptor to monitor pressures. We tested the ventilator splitter circuit in simulation centers between artificial lungs and used an anesthesia gas machine to successfully ventilate two swines. As one of the first studies to demonstrate splitting one anesthesia gas machine between two swines, we present proof-of-concept of a de novo, closed, multiplexing system, with flow restriction for individualized patient therapy. Our studies underscore that while possible, ventilator multiplexing is a complicated synergy between machine settings, circuit modification, and patient monitoring. Consequently, ventilator multiplexing is reserved only as a last emergency resource, by trained clinicians and respiratory therapists with ventilator operative experience.

BackgroundDuring the COVID-19 pandemic, a significant number of healthcare workers have been infected with SARS-CoV-2. However, there remains little knowledge regarding droplet dissemination during airway management procedures in real life settings. Methods12 different airway management procedures were investigated during routine clinical care. A high-speed video camera (1000 frames/second) was for imaging. Quantitative droplet characteristics as size, distance traveled, and velocity were computed. ResultsDroplets were detected in 8/12 procedures. The droplet trajectories could be divided into two distinctive patterns (type 1/2). Type 1 represented a ballistic trajectory with higher speed droplets whereas type 2 represented a random trajectory of slower particles that persisted longer in air. Speaking and coughing lead to a larger amount of droplets than non-invasive ventilation therapy. The use of tracheal cannula filters reduced the amount of droplets. ConclusionsRespiratory droplet patterns generated during airway management procedures follow two distinctive trajectories based on the influence of aerodynamic forces. Speaking and coughing produce more droplets than non-invasive ventilation therapy confirming these behaviors as exposure risks. Even large droplets may exhibit patterns resembling the fluid dynamics smaller airborne aerosols that follow the airflow convectively and may place the healthcare provider at risk.

We present here the design of the Mechanical Ventilator Milano (MVM), a novel mechanical ventilator designed for mass scale production in response to the COVID-19 pandemics, to compensate for the dramatic shortage of such ventilators in many countries. This ventilator is an electro-mechanical equivalent of the old, reliable Manley Ventilator. Our design is optimized to permit large sale production in short time and at a limited cost, relying on off-the-shelf components, readily available worldwide from hardware suppliers. Operation of the MVM requires only a source of compressed oxygen (or compressed medical air) and electrical power. The MVM control and monitoring unit can be connected and networked via WiFi so that no additional electrical connections are necessary other than the connection to the electrical power. At this stage the MVM is not a certified medical device. Construction of the first prototypes is starting with a team of engineers, scientists and computing experts. The purpose of this paper is to disseminate the conceptual design of the MVM broadly and to solicit feed-back from the scientific and medical community to speed the process of review, improvement and possible implementation.

In a major health crisis, demand for mechanical ventilators may exceed supply. This scenario has led to the idea of connecting ventilation circuits in parallel to ventilate multiple patients simultaneously with the same machine. However, simple parallel connection may be harmful when the patients respiratory system mechanics differ. The aim of this work was to develop and test a low-cost, multi-patient, pressure-controlled ventilation system in which parameter settings could be individualized. Two types of circuits were built from polyvinyl chloride plumbing tubes and connectors, with ball valves and water columns used to control pressures. The circuits were connected to test lungs of differing compliances, ventilated in parallel at 20 cycles per minute and assessed for control error, variability and interdependency during peak inspiratory (20 to 35 cmH2O, in 5 cmH2O steps) and positive end-expiratory (5 to 20 to 5 cmH2O, in 5 cmH2O steps) pressure changes in one of the circuits. Results showed control errors lower than 1 cmH2O, a maximum standard deviation in pressure of 1.4 cmH2O and no dependency between the parallel circuits during the pressure maneuvers or a controlled disconnection/reconnection. This pressure-control system might be used to expand a commercial ventilator or, with constant gas inflow and an automated outlet valve, as a stand-alone ventilator with individually-controlled settings for multiple patients. In conclusion, the proposed solution is presented as a potentially reliable strategy for safely individualizing pressure-control parameters in a multi-patient ventilation system during a major health crisis.

As part of a plethora of global efforts to minimize the negative effects of the SARS-CoV2 (COVID-19) pandemic, we developed two different mechanisms that, after further development, could potentially be of use in the future in order to increase the capacity of ventilators with low-cost devices based on single-use-bag-valve mask systems. We describe the concept behind the devices and report a characterization of them. Finally, we make a description of the solved and unsolved challenges and propose a series of measures in order to better cope with future contingencies.

The authors present an easily manufactured modification of Getinge Groups Maquet Flow-i anaesthesia machine that gives it potential to be used long-term as an Intensive Care ventilator for emergency circumstances. There are some 7000 such machines in use worldwide, which could assist in increasing ICU ventilated bed capacity in a number of nations. The authors believe this modification has potential as a solution to increasing ventilator numbers for the COVID-19 pandemic, in hospitals where the Flow-i is underutilised for its designed purpose during this emergency. The technical drawing files are downloadable on the GrabCAD website and are Creative Commons (CC-BY 4.0) licensed to allow local manufacture of the modification. We welcome other Flow-i users and engineers to join us in troubleshooting this project on the associated GrabCAD discussion group during this pre-print phase of research.

Background and ObjectiveThe aim of this study is to develop and validate an automated image segmentation-based frame selection and stitching framework to create enhanced composite images from otoscope videos. The proposed framework, called SelectStitch, is useful for classifying eardrum abnormalities using a single composite image instead of the entire raw otoscope video dataset. MethodsSelectStitch consists of a convolutional neural network (CNN) based semantic segmentation approach to detect the eardrum in each frame of the otoscope video, and a stitching engine to generate a high-quality composite image from the detected eardrum regions. In this study, we utilize two separate datasets: the first one has 36 otoscope videos that were used to train a semantic segmentation model, and the second one, containing 100 videos, which was used to test the proposed method. Cases from both adult and pediatric patients were used in this study. A configuration of 4-levels depth U-Net architecture was trained to automatically find eardrum regions in each otoscope video frame from the first dataset. After the segmentation, we automatically selected meaningful frames from otoscope videos by using a pre-defined threshold, i.e., it should contain at least an eardrum region of 20% of a frame size. We have generated 100 composite images from the test dataset. Three ear, nose, and throat (ENT) specialists (ENT-I, ENT-II, ENT-III) compared in two rounds the composite images produced by SelectStitch against the composite images that were generated by the base processes, i.e., stitching all the frames from the same video data, in terms of their diagnostic capabilities. ResultsIn the first round of the study, ENT-I, ENT-II, ENT-III graded improvement for 58, 57, and 71 composite images out of 100, respectively, for SelectStitch over the base composite, reflecting greater diagnostic capabilities. In the repeat assessment, these numbers were 56, 56, and 64, respectively. We observed that only 6%, 3%, and 3% of the cases received a lesser score than the base composite images, respectively, for ENT-I, ENT-II, and ENT-III in Round-1, and 4%, 0%, and 2% of the cases in Round-2. ConclusionsFrame selection improves the diagnostic quality of composite images from otoscope video clips.

Group singing events have been linked to several outbreaks of infection during the CoVID-19 pandemic, leading to singing activities being banned in many areas across the globe. This link between singing and infection rates supports the possibility that aerosols are partly responsible for person-to-person infection. In contrast to droplets, the smaller aerosol particles do not fall to the ground within a short distance after being expelled by e.g. a singer. Aerosol particles hover and spread via convection in the environmental air. According to the super-spreading theory, choir singing and loud talking (theater and presentations) during rehearsals or performances may constitute a high risk of infectious virus transmission to large numbers of people. Thus, it is essential to define the safety distances between singers in super-spreading situations. The aim of this study is to investigate the impulse dispersion of aerosols during singing and speaking in comparison to breathing and coughing. Ten professional singers (5 males and 5 females) of the Bavarian Radio Chorus performed 9 tasks including singing a phrase of Beethovens 9th symphony, to the original German text. The inhaled air volume was marked with small aerosol particles produced via a commercial e-cigarette. The expelled aerosol cloud was recorded with three high definition TV cameras from different perspectives. Afterwards, the dimensions and dynamics of the aerosol cloud was measured by segmenting the video footage at every time point. While the median expansion was below 1m, the aerosol cloud was expelled up to 1.4m in the singing direction for individual subjects. Consonants produced larger distances of aerosol expulsion than vowels. The dispersion in the lateral and vertical dimension was less pronounced than the forward direction. After completion of each task, the cloud continued to distribute in the air increasing its dimensions. Consequently, we propose increasing the current recommendations of many governmental councils for choirs or singing at religious services from 1.5m to the front and 1m to the side to a distance between choir singers of 2m to the front and 1.5m to the sides.

Acoustic simulations of cochlear implants (CIs) allow for studies of perceptual performance with minimized effects of large CI individual variability. Different from conventional simulations using continuous sinusoidal or noise carriers, the present study employs pulsatile Gaussian-enveloped tones (GETs) to simulate several key features in modern CIs. Subject to the time-frequency uncertainty principle, the GET has a well-defined tradeoff between its duration and bandwidth. Two types of GET vocoders were implemented and evaluated in normal-hearing listeners. In the first implementation, constant 100-Hz GETs were used to minimize within-channel temporal overlap while different GET durations were used to simulate electric channel interaction. This GET vocoder could produce vowel and consonant recognition similar to actual CI performance. In the second implementation, 900-Hz/channel pulse trains were directly mapped to 900-Hz GET trains to simulate the maxima selection and amplitude compression of a widely-used n-of-m processing strategy, or the Advanced Combination Encoder. The simulated and actual implant performance of speech-in-noise recognition was similar in terms of the overall trend, absolute mean scores, and standard deviations. The present results suggest that the pulsatile GET vocoders can be used as alternative vocoders to simultaneously simulate several key CI processing features and result in similar speech perception performance to that with modern CIs.

IntroductionDigital twins derived from 3D scanning data were developed to measure soft tissue deformation in head and neck surgery by an artificial intelligence approach. This framework was applied suggesting feasibility of soft tissue shift detection as a hitherto unsolved problem. MethodsIn a pig head cadaver model 104 soft tissue resection had been performed. The surface of the removed soft tissue (RTP) and the corresponding resection cavity (RC) was scanned (N=416) to train an artificial intelligence (AI) with two different 3D object detectors (HoloLens 2; ArtecEva). An artificial tissue shift (TS) was created by changing the tissue temperature from 7,91{+/-}4,1{degrees}C to 36,37{+/-}1,28{degrees}C. ResultsDigital twins of RTP and RC in cold and warm conditions had been generated and volumes were calculated based on 3D surface meshes. Significant differences in number of vertices created by the different 3D scanners (HoloLens2 51313 vs. ArtecEva 21694, p<0.0001) hence result in differences in volume measurement of the RTC (p=0.0015). A significant TS could be induced by changing the temperature of the tissue of RC (p=0.0027) and RTP (p=<0.0001). RC showed more correlation in TS by heating than RTP with a volume increase of 3.1 l or 9.09% (p=0.449). ConclusionsCadaver models are suitable for training a machine learning model for deformable registration through creation of a digital twin. Despite different point cloud densities, HoloLens and ArtecEva provide only slightly different estimates of volume. This means that both devices can be used for the task.TS can be simulated and measured by temperature change, in which RC and RTP react differently. This corresponds to the clinical behaviour of tumour and resection cavity during surgeries, which could be used for frozen section management and a range of other clinical applications.

IntroductionSARS-CoV-2 is a respiratory virus supposed to enter the organism through aerosol or fomite transmission to the nose, eyes and oropharynx. It is responsible for various clinical symptoms, including hyposmia and other neurological ones. Current literature suggests the olfactory mucosa as a port of entry to the CNS, but how the virus reaches the olfactory groove is still unknown. Because the first neurological symptoms of invasion (hyposmia) do not correspond to first signs of infection, the hypothesis of direct contact through airborne droplets during primary infection and therefore during inspiration is not plausible. The aim of this study is to evaluate if a secondary spread to the olfactory groove in a retrograde manner during expiration could be more probable. MethodsFour three-dimensional virtual models were obtained from actual CT scans and used to simulate expiratory droplets. The volume mesh consists of 25 million of cells, the simulated condition is a steady expiration, driving a flow rate of 270 ml/s, for a duration of 0.6 seconds. The droplet diameter is of 5 m. ResultsThe analysis of the simulations shows the virus to have a high probability to be deployed in the rhinopharynx, on the tail of medium and upper turbinates. The possibility for droplets to access the olfactory mucosa during the expiratory phase is lower than other nasal areas, but consistent. DiscussionThe data obtained from these simulations demonstrates the virus can be deployed in the olfactory groove during expiration. Even if the total amount in a single act is scarce, it must be considered it is repeated tens of thousands of times a day, and the source of contamination continuously acts on a timescale of several days. The present results also imply CNS penetration of SARS-CoV-2 through olfactory mucosa might be considered a complication and, consequently, prevention strategies should be considered in diseased patients.

AO_SCPLOWBSTRACTC_SCPLOWO_ST_ABSObjectivesC_ST_ABSTo compare the sound-source localization, discrimination and tracking performance of bilateral cochlear implant users with omnidirectional (OMNI) and pinna-imitating (PI) microphone directionality modes. DesignTwelve experienced bilateral cochlear implant users participated in the study. Their audio processors were fitted with two different programs featuring either the OMNI or PI mode. Each subject performed static and dynamic sound field spatial hearing tests in the horizontal plane. The static tests consisted of an absolute sound localization test and a minimum audible angle (MAA) test, which was measured at 8 azimuth directions. Dynamic sound tracking ability was evaluated by the subject correctly indicating the direction of a moving stimulus along two circular paths around the subject. ResultsPI mode led to statistically significant sound localization and discrimination improvements. For static sound localization, the greatest benefit was a reduction in the number of front-back confusions. The front-back confusion rate was reduced from 47% with OMNI mode to 35% with PI mode (p = 0.03). The ability to discriminate sound sources at the sides was only possible with PI mode. The MAA value for the sides decreased from a 75.5 to a 37.7-degree angle when PI mode was used (p < 0.001). Furthermore, a non-significant trend towards an improvement in the ability to track sound sources was observed for both trajectories tested (p = 0.34 and p = 0.27). ConclusionsOur results demonstrate that PI mode can lead to improved spatial hearing performance in bilateral cochlear implant users, mainly as a consequence of improved front-back discrimination with PI mode.

ObjectiveIn this prospective study of an in-vivo cervical examination using optical coherence tomography (OCT), we evaluated the diagnostic value of non-invasive and real-time OCT in cervical precancerous lesions and cancer diagnosis, and determined the characteristics of OCT images. Methods733 patients from 5 Chinese hospitals were inspected with OCT and colposcopy-directed biopsy. The OCT images were compared with the histological sections to find out the characteristics of various categories of lesions. The OCT images were also interpreted by 3 investigators to make a 2-class classification, and the results were compared against the pathological results. ResultsVarious structures of the cervical tissue were clearly observed in OCT images, which matched well with the corresponding histological sections. The OCT diagnosis results delivered a sensitivity of 87.0% (95% confidence interval, CI, 82.2%-90.7%), a specificity of 84.1% (95% CI, 80.3%-87.2%), and an overall accuracy of 85.1%. ConclusionBoth good consistency of OCT images and histological images and satisfactory diagnosis results were provided by OCT. Due to its features of non-invasion, real-time, and accuracy, OCT is valuable for the in-vivo evaluation of cervical lesions and has the potential to be one of the routine cervical diagnosis methods.

Intracranial pressure (ICP) is an important parameter to monitor in several neuropathologies. However, because current clinically accepted methods are invasive, its monitoring is limited to patients in critical conditions. On the other side, there are other less critical conditions where ICP monitoring could still be useful, thus there is a need to develop non-invasive methods. We propose a new method to estimate ICP based on the analysis of the non-invasive measurement of pulsatile, microvascular cerebral blood flow with diffuse correlation spectroscopy. This is achieved by training a recurrent neural network using only the cerebral blood flow as the input. The method is validated using a 50% split sample method using the data from a proof-of-concept study. The study involved a population of infants (n=6) with external hydrocephalus (initially diagnosed as benign enlargement of subarachnoid spaces) as well as a population of adults (n=6) suffering from traumatic brain injury. The algorithm was applied to each cohort individually to obtain a model and an ICP estimate. In both diverse cohorts, the non-invasive estimation of ICP was achieved with an accuracy less than <4 mmHg and a negligible small bias. Furthermore, we have achieved a good correlation (Pearsons correlation coefficient >0.9) and good concordance (Lins concordance correlation coefficient >0.9) in comparison to standard clinical, invasive ICP monitoring. This preliminary work paves the way for further investigations of this tool for the non-invasive, bed-side assessment of ICP.

ObjectiveIn mass crisis setting such as the COVID-19 pandemic, the number of patients requiring invasive ventilation may exceed the number of available ventilators. This challenge led to the concept of splitting ventilator between several patients, which aroused interest as well as a strong opposition from multiple professional societies (The joint statement)1.Establishment of a safe ventilator splitting setup which enables monitoring and control of each ventilated patient would be a desirable ability. Achieving independency between the Co-vent patients would enable effective coping with different individual clinical scenarios and broaden the pairing possibilities of patients connected to a single ventilator. We conducted an experiment to determine if our designed setup achieves these goals. MethodsWe utilized a double two limbed modified ventilator circuits which were connected to dual lung simulators. Adding readily available pressure sensors (transducers), PEEP valves, flow control valves, one-way (check) valves and HME filters made the circuit safe enough and suitable for our goals. We first examined a single lung simulator establishing the baseline set parameters, while monitoring ventilator measures as Tidal Volume. The initial ventilator setting we chose was a controlled mandatory ventilation mode with a PIP (peak inspiratory pressure) of 25cmH2O, PEEP (Positive End Expiratory Pressure) of 5 cmH2O. In pressure control set at 20 cmH2O, the recorded mean TV(tidal volume) was 1000 mL (approximately 500 mL/lung simulator) with an average MV(minute ventilation) of 13 L/min (or 6.5 L/min/lung simulator). After examining the system with the dual modified circuits attached, and obtaining all the ventilation parameters, we simulated several clinical scenarios. We simulated clinical events such as: partial or full obstruction, disconnection, air leak and compliance differentials, which occur frequently on a ventilation course. Thus, it is a paramount system demand to keep undisturbed ventilation to the Co-vent patient A, while being challenged by patient B. ResultsThe adaptive split ventilator setup yields increased safety, monitoring, and controls ventilation parameters successfully for each connected simulated patient (using lung simulators).It also enables coping with several common clinical scenarios on a ventilation course, by allowing the care provider to control PIP and PEEP of each Co-Vent patient. ConclusionIn a mass crisis setting, when there is a shortage of ventilators supply, and as a last resort, this setup can be a viable option to act upon. This experiment demonstrates the ability of the split ventilator to ventilate dual lung simulators with increased safety, monitoring and ventilation pressures control of each simulated patient. This split ventilator kept supporting a simulated patient with undisturbed parameters while the CO-vent patient was simulated to be disconnected, having an air leak, or exhibiting lung compliance deterioration. To the best of our knowledge, this is the first time a split ventilator setup demonstrates these capabilities. Our pilot experiment suggests a significant potential of expanding the ventilator support resources, and is especially relevant during COVID-19 outbreak. Since this setup has not been used in a clinical setting yet, further research should be conducted to explore the safety limits and the capabilities of this model.

Mechanical ventilation is essential in the SARS-CoV-2 pandemic context. Considering the limited availability of mechanical ventilators due to high costs increased by global demand, the use of a single ventilator for two or more patients has been encouraged. An experimental model that ventilates two test lungs with a single machine has been designed in order to measure possible asymmetries during parallel circuit ventilation under different lung compliance conditions. This paper reports a first assessment of the risks involved in ventilating two patients with a single machine. Since some volumetric differences are not monitored by the ventilator itself, the main risks involved are distension or alveolar collapse if used in actual patients that have different thoracopulmonary mechanics.

The low success rate in in vitro fertilization (IVF) may be related to our inability to select embryos with good implantation potential by traditional morphology grading and remains a great challenge to clinical practice. Multiple deep learning-based methods have been introduced to improve embryo selection. However, existing methods only achieve limited prediction power and generally ignore the repeated embryo transfers from one stimulated IVF cycle. To improve the deep learning-based models, we introduce Embryo2live, which assesses the multifaceted qualities of embryos from static images taken under standard inverted microscope, primarily in vision transformer frameworks to integrate global features. We first demonstrated its superior performance in predicting Gardners blastocyst grades with up to 9% improvement from the best existing method. We further validated its high capability of supporting transfer learning using the large clinical dataset of the Centre. Remarkably, when applying Embryo2live to the clinical dataset for embryo prioritization, we found it improved the live birth rates of the Top 1 embryo in patients with multiple embryos available for transfer from 23.0% with conventional morphology grading to 71.3% using Embryo2live, reducing the average number of embryo transfers from 2.1 to 1.4 to attain a live birth.

SignificanceA new platform/device is presented that advances hybrid diffuse optical monitors closed to clinical practice, bridging the gap between research-grade optical systems and practical bedside applications. Traditional devices often lack automation, multi-parameter functionality, and operator independence, hence, limiting their usability in demanding clinical environments. By offering automation, user-friendly operation, and overcoming the typical limitations of continuous-wave near-infrared spectroscopy, the hybrid diffuse optical platform (hDOS) provides a more accurate and reliable assessment of both oxygenation and perfusion. This innovation is particularly valuable for monitoring critically ill patients, where precise real-time measurements can directly influence patient management and outcomes. AimTo design, validate, and characterize the platform hDOS that integrates time-domain near-infrared spectroscopy, diffuse correlation spectroscopy, and a pulse oximeter with an automated vascular occlusion test (VOT). The platform aims to support continuous monitoring and the assessment of peripheral microvascular, and metabolic functions in both clinical and field settings. ApproachThe validation strategy for the hDOS device follows a comprehensive approach that goes beyond conventional optical performance assessments. Rather than solely verifying fundamental system parameters, the evaluation comprises of real-world usability, operator and patient safety, and clinical implementation. The devices precision and usability were rigorously tested in vivo through test-retest measurements and comparisons with a commercially available device (INVOS 5100C). This was subsequently followed by a seven-month clinical evaluation at Parc Tauli Hospital Universitari. ResultsThe device underwent extensive validation, accumulating over 200 hours of usage across approximately 150 measurement sessions. The hDOS device exhibited two-fold lower inter-subject and intra-subject variability in baseline tissue oxygen saturation compared to the INVOS 5100C. Furthermore, during a a vascular occlusion challenge, statistically significant differences were observed between the two systems across all extracted parameters. Finally, as a proof of concept, hDOS successfully detected differences in the microvasculature between a general mixed ICU patient cohort (n = 100) and a healthy control group (n = 37). ConclusionsOverall, hDOS device has performed well in both bench-top and realistic clinical applications on patients in vivo. hDOS device provides a unique combination of parameters, available for the first time in a fully automated, self-contained platform.

We tested auditory spatial motion localisation in congenitally hearing impaired adult users of bilateral cochlear implants, and other hearing assistive devices. The group showed severely impaired capabilities despite extensive device use, emphasizing the role of nature in sensory development. We then investigate whether the deficit is maintained for other sensory modalities, by using an in-house sensory substitution device that provides weighted vibrotactile cues on fingertips to induce 3D spatial motion perception. The performance was significantly higher, both in the combined audio-tactile task and the tactile task itself, with accuracy comparable to typically hearing subjects. With touch, we also showed considerably fewer front-back and right-left confusions. The rapid audio-tactile binding and availability of 3D space representation through touch, point to the significant role of nurture in spatial perception development and its amodal nature. The findings show promise towards advancing multisensory solutions for spatial hearing rehabilitation. Highlights- Auditory motion localisation is severely impaired in aided congenitally hearing impaired, supporting the role of nature towards spatial development; - Binding auditory and tactile information enhances auditory spatial performance, supporting the role of nurture; - Hearing impaired individuals perform 360{degrees} motion localisation through touch with accuracy similar to typically hearing; - Surrounding spatial representation never before experienced in congenitally hearing impaired is rapidly available through an alternate modality

AbstractO_ST_ABSSignificanceC_ST_ABSCurrent systems for diffuse optical tomography (DOT) are unsuitable for clinical applications on acute traumatic brain injury (TBI) patients while in the intensive care unit (ICU). AimTo develop and test a method for DOT recordings suitable for TBI patients in the ICU. This method is based on measurements and co-registration using 3-D optical scans, and the acquisition of optical data using a custom-made helmet which would enable a multimodal (invasive and non-invasive) neuromonitoring. ApproachProbe displacements compared to electromagnetic digitization co-registrations were assessed. The capacity to isolate and monitor, using functional near-infrared spectroscopy (fNIRS), the optical signal in the intracranial (ICT) and extracranial tissues (ECT) was tested on 23 healthy volunteers. Participants were scanned with a frequency-domain NIRS device (690 and 830 nm) during 5 Valsalva maneuvers (VM) in a simulated ICU environment. ResultsThe results showed an average error in probe displacement of 5.5 mm, a sufficient capacity to isolate oxyhemoglobin O2Hb (p=6.4{middle dot}10-6) and total hemoglobin HbT (p=2.8{middle dot}10-5) in the ICT from the ECT, and to follow the changes of hemoglobin in the ICT during the VM (O2Hb, p=9.2{middle dot}10-4; HbT, p=1.0{middle dot}10-3). ConclusionsThe developed approach appears to be suitable for use on TBI patients in the ICU.