Linear and Non-Linear Modelling Methods for a Gas Sensor Array Developed for Process Control Applications.

New process developments linked to Power to X (energy storage or energy conversion to another form of energy) require tools to perform process monitoring. The main gases involved in these types of processes are H2, CO, CH4, and CO2. Because of the non-selectivity of the sensors, a multi-sensor matrix has been built in this work based on commercial sensors having very different transduction principles, and, therefore, providing richer information. To treat the data provided by the sensor array and extract gas mixture composition (nature and concentration), linear (Multi Linear Regression-Ordinary Least Square "MLR-OLS" and Multi Linear Regression-Partial Least Square "MLR-PLS") and non-linear (Artificial Neural Network "ANN") models have been built. The MLR-OLS model was disqualified during the training phase since it did not show good results even in the training phase, which could not lead to effective predictions during the validation phase. Then, the performances of MLR-PLS and ANN were evaluated with validation data. Good concentration predictions were obtained in both cases for all the involved analytes. However, in the case of methane, better prediction performances were obtained with ANN, which is consistent with the fact that the MOX sensor's response to CH4 is logarithmic, whereas only linear sensor responses were obtained for the other analytes. Finally, prediction tests performed on one-year aged sensor platforms revealed that PLS model predictions on aged platforms mainly suffered from concentration offsets and that ANN predictions mainly suffered from a drop of sensitivity.

The Reconstructive Metaverse - Collaboration in Real-Time Shared Mixed Reality Environments for Microsurgical Reconstruction.

Plastic surgeons routinely use 3D-models in their clinical practice, from 3D-photography and surface imaging to 3D-segmentations from radiological scans. However, these models continue to be viewed on flattened 2D screens that do not enable an intuitive understanding of 3D-relationships and cause challenges regarding collaboration with colleagues. The Metaverse has been proposed as a new age of applications building on modern Mixed Reality headset technology that allows remote collaboration on virtual 3D-models in a shared physical-virtual space in real-time. We demonstrate the first use of the Metaverse in the context of reconstructive surgery, focusing on preoperative planning discussions and trainee education. Using a HoloLens headset with the Microsoft Mesh application, we performed planning sessions for 4 DIEP-flaps in our reconstructive metaverse on virtual patient-models segmented from routine CT angiography. In these sessions, surgeons discuss perforator anatomy and perforator selection strategies whilst comprehensively assessing the respective models. We demonstrate the workflow for a one-on-one interaction between an attending surgeon and a trainee in a video featuring both viewpoints as seen through the headset. We believe the Metaverse will provide novel opportunities to use the 3D-models that are already created in everyday plastic surgery practice in a more collaborative, immersive, accessible, and educational manner.

Maintenance of beta-blockers and cardiac surgery-related outcomes: a prospective propensity-matched multicentre analysis.

BACKGROUND: We investigated the effects of maintaining beta-blockers on the day of surgery on the incidence of atrial fibrillation and postoperative acute kidney injury (AKI) in patients undergoing cardiac surgery. METHODS: We conducted a multicentre prospective observational study with propensity matching on patients treated with beta-blockers. We collected their baseline patient characteristics, comorbidities, and operative and postoperative outcomes. The endpoints were postoperative atrial fibrillation and AKI after cardiac surgery. RESULTS: Of the 1789 included patients, propensity matching led to 583 patients in each group. Maintenance of beta-blockers was not associated with a reduced risk of atrial fibrillation (odds ratio: 0.86 [95% confidence interval 0.66-1.14], P=0.335; 141 patients [24.2%] vs 126 patients [21.6%]). Sensitivity analysis did not demonstrate association between beta-blocker maintenance and atrial fibrillation after cardiac surgery (odds ratio: 0.93 [95% confidence interval: 0.72-1.22], P=0.625). Maintenance of beta-blockers was associated with a higher rate of norepinephrine use (415 [71.2%] vs 465 [79.8%], P=0.0001) and postoperative AKI (124 [21.3%] vs 159 [27.3%], P=0.0127). No statistically significant difference was observed in ICU length of stay. CONCLUSIONS: Maintenance of beta-blockers on the day of surgery was not associated with a reduced incidence of postoperative atrial fibrillation. However, maintenance of beta-blockers was associated with increased usage of vasopressors, potentially contributing to adverse postoperative renal events. CLINICAL TRIAL REGISTRATION: NCT04769752.

Experimental observation and pressure drop modeling of plug formation in horizontal millifluidic hydraulic conveying.

The hydraulic conveying of glass beads is studied in a horizontal tube. At low flow rates, plugs can be observed moving across the tube, whereas pseudoplugs can be seen at higher flow rates. A statistical analysis of the plugs' and pseudoplugs' velocities and the plugs' lengths observed is conducted. A transition of the propagation speed distribution is established when the crossing over from a plug to a pseudoplug regime is reached, where the peaked plug velocity distribution turns into a uniform pseudoplug velocity distribution. On the other hand, the statistical distribution of plug lengths exhibits a log-normal mathematical shape. The interpretation of the measured pressure drop evolution with the imposed flow rate by means of an effective viscosity shows an apparent shear-thinning effect coming from the dilution of the granular material. This approach provides a predictive tool for pressure drop calculation in the pseudoplug regime.

Immunogenicity of quadrivalent human papillomavirus vaccine among Alaska Native children aged 9-14 years at 5 years after vaccination.

BACKGROUND: Persistent human papillomavirus (HPV) infection can cause anogenital and oropharyngeal cancers. Many HPV infections and HPV-associated cancers are vaccine-preventable. Studies suggest long-term persistence of vaccine-induced antibodies. However, data are limited among Alaska Native people. METHODS: During 2011-2014, we enrolled Alaska Native children aged 9-14 years who received a 3-dose series of quadrivalent HPV vaccine (4vHPV). We collected sera at 1 month and 1, 2, 3, and 5 years post-vaccination to evaluate trends in type-specific immunoglobulin G antibody concentrations for the 4vHPV types (HPV 6/11/16/18). RESULTS: All participants (N = 469) had detectable antibodies against all 4vHPV types at all timepoints post-vaccination. For all 4vHPV types, antibody levels peaked by 1 month post-vaccination and gradually declined in subsequent years. At 5 years post-vaccination, antibody levels were higher among children who received 4vHPV at a younger age. CONCLUSIONS: Alaska Native children maintained antibodies against all 4vHPV types at 5 years post-vaccination.

Increasing DIEA Perforator Detail in 3D Photorealistic Volume Rendering Visualizations with Skin-masking and Cinematic Anatomy.

Preoperative CT angiography (CTA) is increasingly performed prior to perforator flap-based reconstruction. However, radiological 2D thin-slices do not allow for intuitive interpretation and translation to intraoperative findings. 3D volume rendering has been used to alleviate the need for mental 2D-to-3D abstraction. Even though volume rendering allows for a much easier understanding of anatomy, it currently has limited utility as the skin obstructs the view of critical structures. Using free, open-source software, we introduce a new skin-masking technique that allows surgeons to easily create a segmentation mask of the skin that can later be used to toggle the skin on and off. Additionally, the mask can be used in other rendering applications. We use Cinematic Anatomy for photorealistic volume rendering and interactive exploration of the CTA with and without skin. We present results from using this technique to investigate perforator anatomy in deep inferior epigastric perforator flaps and demonstrate that the skin-masking workflow is performed in less than 5 minutes. In Cinematic Anatomy, the view onto the abdominal wall and especially onto perforators becomes significantly sharper and more detailed when no longer obstructed by the skin. We perform a virtual, partial muscle dissection to show the intramuscular and submuscular course of the perforators. The skin-masking workflow allows surgeons to improve arterial and perforator detail in volume renderings easily and quickly by removing skin and could alternatively also be performed solely using open-source and free software. The workflow can be easily expanded to other perforator flaps without the need for modification.

Trends in Otitis Media Ambulatory Visits in American Indian and Alaska Native Children During the Pneumococcal Conjugate Vaccine Period and the COVID-19 Pandemic.

Otitis media-associated outpatient visits among American Indians/Alaska Natives children <5 years old decreased by 52% (100 to 48 per 100 children per year) from 2003 to 2019. Otitis media visits decreased by another 50% from 2019 to 2020, but rebounded between 2020 and 2021 back to a rate similar to 2019.

Occurrences of post-traumatic stress disorder, anxiety, depression, and burnout syndrome in ICU staff workers after two-year of the COVID-19 pandemic: the international PSY-CO in ICU study.

PURPOSE: The present study aimed at assessing the prevalences of post-traumatic stress disorder (PTSD) (main objective), anxiety, depression, and burnout syndrome (BOS) and their associated factors in intensive care unit (ICU) staff workers in the second year of the COVID-19 pandemic. MATERIALS AND METHODS: An international cross-sectional multicenter ICU-based online survey was carried out among the ICU staff workers in 20 ICUs across 3 continents. ICUs staff workers (both caregivers and non-caregivers) were invited to complete PCL-5, HADS, and MBI questionnaires for assessing PTSD, anxiety, depression, and the different components of BOS, respectively. A personal questionnaire was used to isolate independent associated factors with these disorders. RESULTS: PCL-5, HADS, and MBI questionnaires were completed by 585, 570, and 539 responders, respectively (525 completed all questionnaires). PTSD was diagnosed in 98/585 responders (16.8%). Changing familial environment, being a non-caregiver staff worker, having not being involved in a COVID-19 patient admission, having not been provided with COVID-19-related information were associated with PTSD. Anxiety was reported in 130/570 responders (22.8%). Working in a public hospital, being a woman, being financially impacted, being a non-clinical healthcare staff member, having no theoretical or practical training on individual preventive measures, and fear of managing COVID-19 patients were associated with anxiety. Depression was reported in 50/570 responders (8.8%). Comorbidity at risk of severe COVID-19, working in a public hospital, looking after a child, being a non-caregiver staff member, having no information, and a request for moving from the unit were associated with depression. Having received no information and no adequate training for COVID-19 patient management were associated with all 3 dimensions of BOS. CONCLUSION: The present study confirmed that ICU staff workers, whether they treated COVID-19 patients or not, have a substantial prevalence of psychological disorders.

Spatial Fidelity of Microvascular Perforating Vessels as Perceived by Augmented Reality Virtual Projections.

BACKGROUND: Autologous breast reconstruction yields improved long-term aesthetic results but requires increased resources of practitioners and hospital systems. Innovations in radiographic imaging have been increasingly used to improve the efficiency and success of free flap harvest. Augmented reality affords the opportunity to superimpose relevant imaging on a surgeon's native field of view, potentially facilitating dissection of anatomically variable structures. To validate the spatial fidelity of augmented reality projections of deep inferior epigastric perforator flap-relevant anatomy, comparisons of three-dimensional (3D) models and their virtual renderings were performed by four independent observers. Measured discrepancies between the real and holographic models were evaluated. METHODS: The 3D-printed models of deep inferior epigastric perforator flap-relevant anatomy were fabricated from computed tomographic angiography data from 19 de-identified patients. The corresponding computed tomographic angiography data were similarly formatted for the Microsoft HoloLens to generate corresponding projections. Anatomic points were initially measured on 3D models, after which the corresponding points were measured on the HoloLens projections from two separate vantage points (V1 and V2). Statistical analyses, including generalized linear modeling, were performed to characterize spatial fidelity regarding translation, rotation, and scale of holographic projections. RESULTS: Among all participants, the median translational displacement at corresponding points was 9.0 mm between the real-3D model and V1, 12.1 mm between the 3D model and V2, and 13.5 mm between V1 and V2. CONCLUSION: Corresponding points, including topography of perforating vessels, for the purposes of breast reconstruction can be identified within millimeters, but there remain multiple independent contributors of error, most notably the participant and location at which the projection is perceived.

NSAIDs for Pain Control During the Peri-Operative Period of Hip Fracture Surgery: A Systematic Review.

BACKGROUND: Hip fracture (HF) mostly affects older adults and is responsible for increased morbidity and mortality. Non-steroidal anti-inflammatory drugs (NSAIDs) are part of the peri-operative multimodal analgesic management, but their use could be associated with adverse events in older adults. This systematic review aimed to assess outcomes associated with NSAIDs use in the peri-operative period of HF surgery. METHODS: This systematic review was conducted according to the PRISMA guidelines. Three databases (PubMed/EMBASE/Cochrane Central) were used to search for clinical trials and observational studies assessing efficacy, safety and impact of NSAIDs use on non-specific post-operative outcomes, such as functional status and post-operative complications. RESULTS: Among the 1320 references initially identified, four provided data on efficacy, four on safety and six on non-specific post-operative outcomes (three randomized controlled clinical trials, three observational studies). Mean study population ages ranged from 68 to 87 years. Two studies found that NSAIDs were effective on pain control, but two studies found conflicting results on opioid sparing. No increased risk of acute kidney injury was observed, while results concerning bleeding risk and delirium were conflicting. No study has found any effect of NSAIDs use on walk recovery. Quality of evidence was high for pain control, but low to very low for all the other studied outcomes. CONCLUSIONS: The use of NSAIDs may be effective for pain control in the peri-operative period of HF surgery. However, safety data were conflicting with low levels of certainty. Further studies are needed to assess their benefit-risk balance in this context. The research protocol was previously registered on PROSPERO (registration number: CRD42021237649).

Mean systemic filling pressure and venous return to assess the effects of passive leg raising and volume expansion in acute circulatory failure patients: a posthoc analysis of a multi-centre prospective study.

BACKGROUND: The main aim of the study was to investigate the behaviours of the mean systemic filling pressure (Pmsf), calculated by the mathematical method, and its derived variables of venous return after volume expansion (VE) and passive leg raising (PLR), with analysis according to fluid and PLR responsiveness. METHODS: This was a post-hoc analysis of a multicentre prospective study. We included 202 mechanically ventilated patients with acute circulatory failure. Pmsf, dVR (difference between Pmsf and central venous pressure [CVP]), and resistance to venous return (RVR) were calculated before/after PLR and before/after VE. Fluid- and PLR-responsiveness were defined according to the increase in cardiac index (CI) >15% after VE and >10% after PLR, respectively. RESULTS: Pmsf increased significantly after VE and PLR in both fluid and PLR-responder and non-responder groups. In fluid-responder patients, the increase in dVR was significantly higher than in non-responder group (1.5 [IQR:1.0-2.0] vs. 0.3 [IQR:-0.1-0.6] mmHg, p < 0.001) because of the larger increase in CVP relative to Pmsf in the non-responder group. The same findings were observed after PLR. RVR significantly decreased only in the fluid-responder and PLR-responder groups after VE and PLR. CONCLUSIONS: Venous return, derived from the mathematical model, increased in preload-dependent patients after VE and PLR because of the larger increases in Pmsf relative to CVP and the decreases in RVR. In preload-independent patients, VR did not change because of the larger rise in CVP compared to Pmsf after VE and PLR. These findings agree with the physiological model of circulation described by Guyton.

Determinants of postoperative complications in high-risk noncardiac surgery patients optimized with hemodynamic treatment strategies: A post-hoc analysis of a randomized multicenter clinical trial.

STUDY OBJECTIVE: This post-hoc analysis of a randomized controlled trial was undertaken to establish the determinants of postoperative complications and acute kidney injury in high-risk noncardiac surgery patients supported with hemodynamic treatment strategies. DESIGN: We conducted a post-hoc analysis of patients enrolled in the OPtimization Hemodynamic Individualized by the respiratory QUotiEnt (OPHIQUE) trial. SETTING: Operating rooms in four university medical centers and one non-university hospital from December 26, 2018, to September 9, 2021. PATIENTS: We enrolled 350 patients with a high risk of postoperative complications undergoing high-risk noncardiac surgery lasting 2 h or longer under general anesthesia. INTERVENTIONS: All patients were treated according to hemodynamic treatment strategies which included cardiac output optimization by titration of fluid challenge and targeted systolic blood pressure to remain within ±10% of the reference value. MEASUREMENTS: We assessed the association between pre-operative and intra-operative exposure of interest with a composite primary outcome of major complications or death within seven days following surgery using a multivariable logistic regression model. We also assessed the association between these exposures of interest and acute kidney injury. MAIN RESULTS: The data of 341 patients were analyzed. In multivariate analysis, the factors independently associated with the primary outcome were age (OR = 1.04 (1.01-1.06), P = 0.002), preoperative hemoglobin concentration (OR = 0.85 (0.75-0.96), P = 0.012), non-vascular surgery (OR = 0.30 (0.17-0.53), P < 0.0001), and intraoperative surgical complications (OR = 2.08 (1.02-4.24), P = 0.046). The factors independently associated with postoperative acute kidney injury were age (OR = 1.04 (1.01-1.08), P = 0.008), preoperative creatinine concentration (OR = 1.01 (1.00-1.01), P = 0.049), non-vascular surgery (OR = 0.36 (0.20-0.66), P = 0.001), and intraoperative surgical complications (OR = 3.36 (1.50-7.55), P = 0.031). CONCLUSIONS: Surgical complications, a lower preoperative hemoglobin concentration, age, and vascular surgery were associated with postoperative complications in a high-risk noncardiac surgery population supported with hemodynamic treatment strategies.

Invasive Pneumococcal Disease and Potential Impact of Pneumococcal Conjugate Vaccines Among Adults, Including Persons Experiencing Homelessness-Alaska, 2011-2020.

BACKGROUND: Adults aged ≥65 years, adults with certain underlying medical conditions, and persons experiencing homelessness are at increased risk for invasive pneumococcal disease (IPD). Two new pneumococcal conjugate vaccines, 15-valent pneumococcal conjugate vaccine (PCV15) and 20-valent pneumococcal conjugate vaccine (PCV20), were recently approved for use in US adults. We describe the epidemiology of IPD among Alaska adults and estimate the proportion of IPD cases potentially preventable by new vaccines. METHODS: We used statewide, laboratory-based surveillance data to calculate and compare IPD incidence rates and 95% confidence intervals (CIs) among Alaska adults aged ≥18 years during 2011-2020 and estimate the proportion of IPD cases that were caused by serotypes in PCV15 and PCV20. RESULTS: During 2011-2020, 1164 IPD cases were reported among Alaska adults for an average annual incidence of 21.3 cases per 100 000 adults per year (95% CI, 20.1-22.5). Incidence increased significantly during the study period (P < .01). IPD incidence among Alaska Native adults was 4.7 times higher than among non-Alaska Native adults (95% CI, 4.2-5.2). Among adults experiencing homelessness in Anchorage, IPD incidence was 72 times higher than in the general adult population (95% CI, 59-89). Overall, 1032 (89%) Alaska adults with IPD had an indication for pneumococcal vaccine according to updated vaccination guidelines; 456 (39%) and 700 (60%) cases were caused by serotypes in PCV15 and PCV20, respectively. CONCLUSIONS: Use of PCV15 and PCV20 could substantially reduce IPD among adults in Alaska, including Alaska Native adults and adults experiencing homelessness.

Passive leg raising test induced changes in plethysmographic variability index to assess fluid responsiveness in critically ill mechanically ventilated patients with acute circulatory failure.

BACKGROUND: Passive leg raising (PLR) reliably predicts fluid responsiveness but requires a real-time cardiac index (CI) measurement or the presence of an invasive arterial line to achieve this effect. The plethysmographic variability index (PVI), an automatic measurement of the respiratory variation of the perfusion index, is non-invasive and continuously displayed on the pulse oximeter device. We tested whether PLR-induced changes in PVI (ΔPVIPLR) could accurately predict fluid responsiveness in mechanically ventilated patients with acute circulatory failure. METHODS: This was a secondary analysis of an observational prospective study. We included 29 mechanically ventilated patients with acute circulatory failure in this study. We measured PVI (Radical-7 device; Masimo Corp., Irvine, CA) and CI (Echocardiography) before and during a PLR test and before and after volume expansion of 500 mL of crystalloid solution. A volume expansion-induced increase in CI of >15% defined fluid responsiveness. To investigate whether ΔPVIPLR can predict fluid responsiveness, we determined areas under the receiver operating characteristic curves (AUROCs) and gray zones for ΔPVIPLR. RESULTS: Of the 29 patients, 27 (93.1%) received norepinephrine. The median tidal volume was 7.0 [IQR: 6.6-7.6] mL/kg ideal body weight. Nineteen patients (65.5%) were classified as fluid responders (increase in CI > 15% after volume expansion). Relative ΔPVIPLR accurately predicted fluid responsiveness with an AUROC of 0.89 (95%CI: 0.72-0.98, p < 0.001). A decrease in PVI ≤ -24.1% induced by PLR detected fluid responsiveness with a sensitivity of 95% (95%CI: 74-100%) and a specificity of 80% (95%CI: 44-97%). Gray zone was acceptable, including 13.8% of patients. The correlations between the relative ΔPVIPLR and changes in CI induced by PLR and by volume expansion were significant (r = -0.58, p < 0.001, and r = -0.65, p < 0.001; respectively). CONCLUSIONS: In sedated and mechanically ventilated ICU patients with acute circulatory failure, PLR-induced changes in PVI accurately predict fluid responsiveness with an acceptable gray zone. TRIAL REGISTRATION: ClinicalTrials.govNCT03225378.

Prompt tuning for parameter-efficient medical image segmentation.

Neural networks pre-trained on a self-supervision scheme have become the standard when operating in data rich environments with scarce annotations. As such, fine-tuning a model to a downstream task in a parameter-efficient but effective way, e.g. for a new set of classes in the case of semantic segmentation, is of increasing importance. In this work, we propose and investigate several contributions to achieve a parameter-efficient but effective adaptation for semantic segmentation on two medical imaging datasets. Relying on the recently popularized prompt tuning approach, we provide a prompt-able UNETR (PUNETR) architecture, that is frozen after pre-training, but adaptable throughout the network by class-dependent learnable prompt tokens. We pre-train this architecture with a dedicated dense self-supervision scheme based on assignments to online generated prototypes (contrastive prototype assignment, CPA) of a student teacher combination. Concurrently, an additional segmentation loss is applied for a subset of classes during pre-training, further increasing the effectiveness of leveraged prompts in the fine-tuning phase. We demonstrate that the resulting method is able to attenuate the gap between fully fine-tuned and parameter-efficiently adapted models on CT imaging datasets. To this end, the difference between fully fine-tuned and prompt-tuned variants amounts to 7.81 pp for the TCIA/BTCV dataset as well as 5.37 and 6.57 pp for subsets of the TotalSegmentator dataset in the mean Dice Similarity Coefficient (DSC, in %) while only adjusting prompt tokens, corresponding to 0.51% of the pre-trained backbone model with 24.4M frozen parameters. The code for this work is available on https://github.com/marcdcfischer/PUNETR.

The Impact of Occlusion on Depth Perception at Arm's Length.

This paper investigates the accuracy of Augmented Reality (AR) technologies, particularly commercially available optical see-through displays, in depicting virtual content inside the human body for surgical planning. Their inherent limitations result in inaccuracies in perceived object positioning. We examine how occlusion, specifically with opaque surfaces, affects perceived depth of virtual objects at arm's length working distances. A custom apparatus with a half-silvered mirror was developed, providing accurate depth cues excluding occlusion, differing from commercial displays. We carried out a study, contrasting our apparatus with a HoloLens 2, involving a depth estimation task under varied surface complexities and illuminations. In addition, we explored the effects of creating a virtual "hole" in the surface. Subjects' depth estimation accuracy and confidence were a ssessed. Results showed more depth estimation variation with HoloLens and significant depth error beneath complex occluding surfaces. However, creating a virtual hole significantly reduced depth errors and increased subjects' confidence, irrespective of accuracy enhancement. These findings have important implications for the design and use of mixed-reality technologies in surgical applications, and industrial applications such as using virtual content to guide maintenance or repair of components hidden beneath the opaque outer surface of equipment. A free copy of this paper and all supplemental materials are available at https://bit.ly/3YbkwjU.