Mechanical ventilation guided by driving pressure optimizes local pulmonary biomechanics in an ovine model.

Mechanical ventilation exposes the lung to injurious stresses and strains that can negatively affect clinical outcomes in acute respiratory distress syndrome or cause pulmonary complications after general anesthesia. Excess global lung strain, estimated as increased respiratory system driving pressure, is associated with mortality related to mechanical ventilation. The role of small-dimension biomechanical factors underlying this association and their spatial heterogeneity within the lung are currently unknown. Using four-dimensional computed tomography with a voxel resolution of 2.4 cubic millimeters and a multiresolution convolutional neural network for whole-lung image segmentation, we dynamically measured voxel-wise lung inflation and tidal parenchymal strains. Healthy or injured ovine lungs were evaluated as the mechanical ventilation positive end-expiratory pressure (PEEP) was titrated from 20 to 2 centimeters of water. The PEEP of minimal driving pressure (PEEPDP) optimized local lung biomechanics. We observed a greater rate of change in nonaerated lung mass with respect to PEEP below PEEPDP compared with PEEP values above this threshold. PEEPDP similarly characterized a breaking point in the relationships between PEEP and SD of local tidal parenchymal strain, the 95th percentile of local strains, and the magnitude of tidal overdistension. These findings advance the understanding of lung collapse, tidal overdistension, and strain heterogeneity as local triggers of ventilator-induced lung injury in large-animal lungs similar to those of humans and could inform the clinical management of mechanical ventilation to improve local lung biomechanics.

Risk of hydrogen sulfide pollution from pressure release resulting from landfill mining.

Landfill mining (LFM) has gained widespread recognition due to its benefits in terms of resource utilization of landfill waste and reuse of landfill sites. However, it is important to thoroughly assess the associated environmental risks. This study simulated the pressure release induced from LFM in small-scale batch anaerobic reactors subject to different initial pressures (0.2-0.6 MPa). The potential risk of hydrogen sulfide (H2S) pollution resulting from pressure release caused by LFM was investigated. The results demonstrated that the concentration of H2S significantly increased following the simulated pressure treatments. At the low (25 °C) and high (50 °C) temperatures tested, the peak H2S concentration reached 19366 and 24794 mg·m-3, respectively. Both of these concentrations were observed under highest initial pressure condition (0.6 MPa). However, the duration of H2S release was remarkably longer (>90 days) at the low temperature tested. Microbial diversity analysis results revealed that, at tested low temperature, the sulfate-reducing bacteria (SRB) communities of various pressure-bearing environments became phylogenetically similar following the pressure releases. In contrast, at the high temperature tested, specific SRB genera (Desulfitibacter and Candidatus Desulforudis) showed further enrichment. Moreover, the intensified sulfate reduction activity following pressure release was attributed to the enrichment of specific SRBs, including Desulfovibrio (ASV585 and ASV1417), Desulfofarcimen (ASV343), Candidatus Desulforudis (ASV24), and Desulfohalotomaculum (ASV506 and ASV2530). These results indicate that the pressure release associated with LFM significantly increases the amount of H2S released from landfills, and the SRB communities have different response mechanisms to pressure release at different temperature conditions. This study highlights the importance of considering the potential secondary environmental risks associated with LFM.

Mechanical consequences to the annulus fibrosus following rapid internal pressurization and endplate fracture under restrained-expansion conditions.

Intervertebral disc herniation is not a common injury in the adolescent population, but the correlation between trauma and herniation warrants concern. Previous research demonstrated the capacity for rapid internal pressurization to reduce the mechanical integrity of the intervertebral disc's annulus fibrosus, even in the absence of fracture. The purpose of this study was to modify previous internal pressurization procedures towards a more transferable injury model, then investigate the capacity for these procedures to damage the mechanical integrity of the annulus fibrosus. Porcine cervical motion segments with intact facet joints were confined between a vice and force plate under 300 N of static compression, then a single, manual, rapid internal pressurization was delivered. Posterolateral annulus samples were extracted and situated in a 180° peel test configuration, exposing the interlamellar matrix of samples to separations of 0.5 mm/s, until complete separation of the sample occurred. Multilayer tensile testing was performed on superficial and mid-span samples of annulus by applying uniaxial tension of 1 %/s to 50 % strain. Compared to unpressurized controls, rapid pressurization causing fracture resulted in reduced lamellar adhesion and increased toe-region stress and strain properties in the annulus. Morphological assessment reported similar fracture patterns between endplate fractures achieved in the present experiment and endplate fractures documented in human patients. Mechanical plus morphological results suggest that rapid internal pressurization resulting in endplate fracture may represent a potent mechanism for subsequent damage to the intervertebral disc.

Effect of different inner pressures of air insoles and walking durations on plantar pressure time integral.

Air insoles have provided insights for reducing the risk of diabetic foot ulcers (DFU). The pressure time integral (PTI) is an effective assessment that considers the time effect in various physical activities. We investigated the interactions between three different insole inner pressures (80, 160, and 240 mmHg) and two walking durations (10 and 20 min). The big toe (T1), first metatarsal head (M1), and second metatarsal head (M2) were investigated in 13 healthy participants. One-way analysis of variance (ANOVA) showed that the effects of each insole inner pressure significantly differed (P < 0.05) with a 10 min walking duration. The PTI values resulting from 80 mmHg in M2 (38.4 ± 3.8, P = 0.002) and 160 mmHg in M1 (44.3 ± 4.3, P = 0.027) were lower than those from 240 mmHg. Additionally, the paired t test showed that the effects of each walking duration were also considerably different at 160 mmHg. The PTI at 10 min was lower than that at 20 min in M1 (44.31 ± 4.31, P = 0.015) and M2 (47.14 ± 5.27, P = 0.047). Thus, we suggest that walking with a pressure of 160 mmHg for 10 min has a lower risk of DFU.

Evaluation of surgical condition during laparoscopic gynaecological surgery in patients with moderate vs. deep neuromuscular block in low-pressure pneumoperitoneum.

INTRODUCTION: The significant effect of deep neuromuscular block (NMB) in laparoscopic surgery is still controversial, especially in lower-pressure pneumoperitoneum. This study investigates the effect of deep neuromuscular block on intraabdominal pressure (IAP), surgical space quality, post-operative abdominal pain, and shoulder tip pain in laparoscopic gynaecological surgery. MATERIAL AND METHODS: This is a randomised, double-blinded control trial which randomised samples to moderate NMB (train-of-four count [TOF] of 1 or 2) or deep NMB (post-tetanic count [PTC] of 1 or 2). Surgery began with IAP 8 mmHg but was allowed to increase the pressure if the surgical condition was unfavourable. The surgical condition was rated on a 4-point scale. Post-operative abdominal pain and shoulder tip pain was assessed using a numerical rating scale for pain, with 0 defined as no pain and 10 severe pain at recovery area (time 0), 30 minutes, and 24 hours post-operation. RESULTS: Seventy patients completed the study. The rate of increasing IAP between the 2 groups ( P = 0.172) is not significant, but deep NMB requires less pressure - mean highest IAP of 10.31 (± 1.39) mmHg, moderate NMB 11.54 (± 1.69) mmHg. The mean surgical space condition score was significantly better in the deep NMB group at 2.4 (± 0.7) compared to moderate NMB at 3.2 (± 0.66), P < 0.005. There was a significantly lower post-operative abdominal pain score in deep NMB but no significant difference in shoulder tip pain score between the 2 groups. CONCLUSIONS: Deep NMB enables the usage of lower IAP in laparoscopic surgery without interfering with surgical space condition, and it reduces the post-operative abdominal pain score in 24 hours compared to moderate NMB.

Incorporating body mass index into esophageal manometry metrics and mean nocturnal baseline impedance for the evaluation of gastro-esophageal reflux disease.

This study aims to enhance the effectiveness of high resolution manometry (HRM) and pH-impedance monitoring metrics in distinguishing between gastro-esophageal reflux disease (GERD) and non-GERD. A retrospective propensity score matching (PSM) study was conducted on 643 patients with GERD symptoms. PSM matched 134 GERD patients with 134 non-GERD controls. Body mass index (BMI), intra-esophageal pressure (IEP) and intra-gastric pressure (IGP) were significantly higher in the GERD group compared to the non-GERD group. BMI was correlated with IEP and IGP positively. IGP was positively correlated with esophagogastric (EGJ) pressure (EGJ-P) in participants with EGJ type 1 and 2, but not in participants with EGJ type 3. BMI was correlated with distal MNBI negatively. Logistic regression showed BMI as an independent risk factor for GERD. Receiver operating characteristic curve (ROC) and decision curve analysis (DCA) showed that BMI adjusted EGJ contractile integral (EGJ-CI) and BMI adjusted MNBI were superior to the corresponding original ones in predicting GERD susceptibility. According to the findings, BMI and IGP are the main factors contributing to the development of GERD. BMI affects IEP through the adaptive response of EGJ-P to IGP. Incorporating BMI into the calculations of EGJ-CI and MNBI can improve their ability in predicting GERD susceptibility.

Probing the structural stability of R-phycocyanin under pressure.

The red macroalgae Porphyra, commonly known as Nori, is widely used as food around the world due to its high nutrient content, including the significant abundance of colored phycobiliproteins (PBPs). Among these, R-phycocyanin (R-PC) stands out for its vibrant purple color and numerous bioactive properties, making it a valuable protein for the food industry. However, R-PC's limited thermal stability necessitates alternative processing methods to preserve its color and bioactive properties. Our study aimed to investigate the in-situ stability of oligomeric R-PC under high pressure (HP) conditions (up to 4000 bar) using a combination of absorption, fluorescence, and small-angle X-ray scattering (SAXS) techniques. The unfolding of R-PC is a multiphase process. Initially, low pressure induces conformational changes in the R-PC oligomeric form (trimers). As pressure increases above 1600 bar, these trimers dissociate into monomers, and at pressures above 3000 bar, the subunits begin to unfold. When returned to atmospheric pressure, R-PC partially refolds, retaining 50% of its original color absorbance. In contrast, heat treatment causes irreversible and detrimental effects on R-PC color, highlighting the advantages of HP treatment in preserving both the color and bioactive properties of R-PC compared to heat treatment.

Interference haptic stimulation and consistent quantitative tactility in transparent electrotactile screen with pressure-sensitive transistors.

Integrating tactile feedback through haptic interfaces enhances experiences in virtual and augmented reality. However, electrotactile systems, which stimulate mechanoreceptors directly, often yield inconsistent tactile results due to variations in pressure between the device and the finger. In this study, we present the integration of a transparent electrotactile screen with pressure-sensitive transistors, ensuring highly consistent quantitative haptic sensations. These transistors effectively calibrate tactile variations caused by touch pressure. Additionally, we explore remote-distance tactile stimulations achieved through the interference of electromagnetic waves. We validated tactile perception using somatosensory evoked potentials, monitoring the somatosensory cortex response. Our haptic screen can stimulate diverse electrotactile sensations and demonstrate various tactile patterns, including Morse code and Braille, when integrated with portable smart devices, delivering a more immersive experience. Furthermore, interference of electric fields allows haptic stimulation to facilitate diverse stimulus positioning at lower current densities, extending the reach beyond direct contact with electrodes of our screen.

High-Pressure Freezing and Low-Temperature Processing of Seeds for Electron Microscopy and Electron Tomography.

High-pressure freezing/freeze substitution has been used to preserve biological samples for ultrastructure study instead of chemical fixation. For most plant samples, the water content is too high and cannot be properly preserved during cryofixation. Additionally, the cell wall is a barrier that prevents the substitution of water with the resin. In this chapter, we will discuss modified high-pressure freezing and subsequent processing protocols based on our routinely used methodology for examining Arabidopsis seeds in transmission electron microscopy and electron tomography.

Factors predicting the use of the backward upward rightward pressure maneuver in thyroid surgery: a single-center retrospective cohort study.

BACKGROUND: The purpose of this study was to evaluate the predictability of utilizing the backward upward rightward pressure (BURP) maneuver and the efficacy of related tests in patients with a challenging airway and a Mallampati score of 2 or higher who underwent scheduled elective thyroid surgery. METHODS: Patient files were scanned for 300 adult patients who had undergone thyroid surgery under general anesthesia. The information included their medical history of thyroid disease, previous thyroid surgery, and evaluation tests for difficult intubation such as Mallampati score, maximum mouth opening, ease of intubation, thyroid goitre grade, and whether the BURP maneuver was performed. Patients who had a history of difficult intubation or a Cormack Lehane score less than 2 were excluded. Additionally, the patients were divided into two groups: one group underwent the BURP maneuver (n = 78) and the other did not (n = 56). RESULTS: Statistically significant differences in the maximum mouth openings and thyroid goitre grade were observed between the groups according to the preoperative evaluation. Furthermore, significant differences were noted between the groups in terms of the ease of intubation, intubation time, Cormack-Lehane score, and number of intubation attempts. CONCLUSION: There may be a correlation between the maximum mouth opening and thyroid goitre grade in predicting the use of the BURP maneuver. It is important to keep in mind, however, that difficult intubation may occur in some uncommon types of goiter, such as retrosternal goiter, even if the thyroid gland size is small. Therefore, it may be useful to consider performing the BURP maneuver.

Effects of a range of 6 prefabricated orthotic insole designs on plantar pressure in a healthy population: A randomized, open-label crossover investigation.

BACKGROUND: Prefabricated orthotic insoles are widely commercially available for self-selection to treat foot and lower-body musculoskeletal pain, without requiring advice from health care professionals. Although they are generally designed to mimic traditional design features of custom-made orthotics used in clinical practice, the effects of prefabricated insoles on plantar pressure distribution are poorly understood. OBJECTIVE: This investigation aimed to evaluate and directly compare the effects of a range of 6 different commercially available prefabricated orthotic insole designs on plantar pressure in healthy individuals. METHODS: This was a single-center, randomized, open-label, crossover investigation. In-shoe dynamic pressure (F-scan) was investigated in 24 healthy subjects with normal foot posture, wearing standard shoes alone and in combination with 6 different orthotic insoles, consecutively, measured on a single day. The biomechanical impact of each insole was determined by the statistical significance of changes from baseline measurements (standard shoe alone). RESULTS: Insoles with heel cups and medial arch geometries consistently increased contact area at medial arch and whole-foot regions and reduced both plantar peak pressure (PP) and pressure time integral at medial arch and heel regions. CONCLUSIONS: This investigation has aided in further understanding the mode of action of prefabricated insoles in a healthy population. The insoles in this study redistributed plantar pressure at key regions of the foot, based on design features common to prefabricated insoles. Prefabricated orthotic insoles represent an easily accessible means of reducing lower-body musculoskeletal stress for those who spend prolonged periods of time on their feet.

Enhancing the membrane bioreactor efficiency: The impact of rotating membrane modules and aeration strategies on the transmembrane pressure.

The study analyses the performance of a pilot plant using a rotating hollow fibre (HF) membrane bioreactor system. The experiments evaluated the effect of operational parameters such as rotational speed, aeration strategies, and maintenance cleaning (MC) procedures on the efficiency of the system, in particular transmembrane pressure (TMP) and filtrate quality. The results indicate that the rotating membrane module reduces TMP increase and can operate for 48 days with satisfactory performance, even without aeration. This has the potential to significantly improve efficiency, resulting in significant energy savings. In addition, two MC methods, clean in air and clean in place, were tested and found to be efficient for weekly MC. It was observed that operating without aeration during colder seasons may not be effective. Therefore, adaptive strategies are needed to address seasonal temperature variations.

Pressure-enhanced sensing of tissue oxygenation via endogenous porphyrin: Implications for dynamic visualization of cancer in surgery.

Fluorescence guidance is routinely used in surgery to enhance perfusion contrast in multiple types of diseases. Pressure-enhanced sensing of tissue oxygenation (PRESTO) via fluorescence is a technique extensively analyzed here, that uses an FDA-approved human precursor molecule, 5-aminolevulinic acid (ALA), to stimulate a unique delayed fluorescence signal that is representative of tissue hypoxia. The ALA precontrast agent is metabolized in most tissues into a red fluorescent molecule, protoporphyrin IX (PpIX), which has both prompt fluorescence, indicative of the concentration, and a delayed fluorescence, that is amplified in low tissue oxygen situations. Applied pressure from palpation induces transient capillary stasis and a resulting transient PRESTO contrast, dominant when there is near hypoxia. This study examined the kinetics and behavior of this effect in both normal and tumor tissues, with a prolonged high PRESTO contrast (contrast to background of 7.3) across 5 tumor models, due to sluggish capillaries and inhibited vasodynamics. This tissue function imaging approach is a fundamentally unique tool for real-time palpation-induced tissue response in vivo, relevant for chronic hypoxia, such as vascular diseases or oncologic surgery.

Case Study on the design optimization of the positive pressure operating room.

Ventilation systems of operating rooms (ORs) are significantly important in preventing postoperative wound infections that can cause morbidity and mortality after surgery in or out of the hospital. This study aims to identify the optimum overpressure for efficient operation while reducing the risk of surgical site infections (SSIs) based on the actual OR with the help of computational fluid dynamics. The species transport model, Lagrangian discrete phase model, and turbulent standard k- ε model are mainly used for the transient numerical study to improve the performance of the OR and reduce SSI cases. Four OR schemes were initially calculated for the best location of the patient on the surgical table. The results revealed that the modified position 90˚ is the best location with the minimum CO2 and BCP concentrations. The investigated operating room could host up to ten surgical members with the optimum overpressure of 5.89 Pa and 0.56 m/s of supply velocity under the standard cleanliness level. Modifying the supply surface area will enhance the performance of the operating room by providing a cleaner zone and maintaining the desired room pressure, even with a low airflow rate. This optimization scheme could guide practical applications in all positively pressurized operating rooms to address issues related to overpressure effects.

Calibrating Low-Cost Smart Insole Sensors with Recurrent Neural Networks for Accurate Prediction of Center of Pressure.

This paper proposes a scheme for predicting ground reaction force (GRF) and center of pressure (CoP) using low-cost FSR sensors. GRF and CoP data are commonly collected from smart insoles to analyze the wearer's gait and diagnose balance issues. This approach can be utilized to improve a user's rehabilitation process and enable customized treatment plans for patients with specific diseases, making it a useful technology in many fields. However, the conventional measuring equipment for directly monitoring GRF and CoP values, such as F-Scan, is expensive, posing a challenge to commercialization in the industry. To solve this problem, this paper proposes a technology to predict relevant indicators using only low-cost Force Sensing Resistor (FSR) sensors instead of expensive equipment. In this study, data were collected from subjects simultaneously wearing a low-cost FSR Sensor and an F-Scan device, and the relationship between the collected data sets was analyzed using supervised learning techniques. Using the proposed technique, an artificial neural network was constructed that can derive a predicted value close to the actual F-Scan values using only the data from the FSR Sensor. In this process, GRF and CoP were calculated using six virtual forces instead of the pressure value of the entire sole. It was verified through various simulations that it is possible to achieve an improved prediction accuracy of more than 30% when using the proposed technique compared to conventional prediction techniques.

Center of Pressure Measurement Accuracy via Insoles with a Reduced Pressure Sensor Number during Gaits.

The objective was to compare simplified pressure insoles integrating different sensor numbers and to identify a promising range of sensor numbers for accurate center of pressure (CoP) measurement. Twelve participants wore a 99-sensor Pedar-X insole (100 Hz) during walking, jogging, and running. Eight simplified layouts were simulated, integrating 3-17 sensors. Concordance correlation coefficients (CCC) and root mean square errors (RMSE) between the original and simplified layouts were calculated for time-series mediolateral (ML) and anteroposterior (AP) CoP. Differences between layouts and between gait types were assessed via ANOVA and Friedman test. Concordance between the original and simplified layouts varied across layouts and gaits (CCC: 0.43-0.98; χ(7)2 ≥ 34.94, p < 0.001). RMSEML and RMSEAP [mm], respectively, were smaller in jogging (5 ± 2, 15 ± 9) than in walking (8 ± 2, 22 ± 4) and running (7 ± 4, 20 ± 7) (ηp2: 0.70-0.83, p < 0.05). Only layouts with 11+ sensors achieved CCC ≥ 0.80 in all tests across gaits. The 13-sensor layout achieved CCC ≥ 0.95 with 95% confidence, representing the most promising compromise between sensor number and CoP accuracy. Future research may refine sensor placement, suggesting the use of 11-13 sensors. For coaches, therapists, and applied sports scientists, caution is recommended when using insoles with nine or fewer sensors. Consulting task-specific validation results for the intended products is advisable.

Optimization of activity-driven event detection for long-term ambulatory urodynamics.

Lower urinary tract dysfunction (LUTD) is a debilitating condition that affects millions of individuals worldwide, greatly diminishing their quality of life. The use of wireless, catheter-free implantable devices for long-term ambulatory bladder monitoring, combined with a single-sensor system capable of detecting various bladder events, has the potential to significantly enhance the diagnosis and treatment of LUTD. However, these systems produce large amounts of bladder data that may contain physiological noise in the pressure signals caused by motion artifacts and sudden movements, such as coughing or laughing, potentially leading to false positives during bladder event classification and inaccurate diagnosis/treatment. Integration of activity recognition (AR) can improve classification accuracy, provide context regarding patient activity, and detect motion artifacts by identifying contractions that may result from patient movement. This work investigates the utility of including data from inertial measurement units (IMUs) in the classification pipeline, and considers various digital signal processing (DSP) and machine learning (ML) techniques for optimization and activity classification. In a case study, we analyze simultaneous bladder pressure and IMU data collected from an ambulating female Yucatan minipig. We identified 10 important, yet relatively inexpensive to compute signal features, with which we achieve an average 91.5% activity classification accuracy. Moreover, when classified activities are included in the bladder event analysis pipeline, we observe an improvement in classification accuracy, from 81% to 89.0%. These results suggest that certain IMU features can improve bladder event classification accuracy with low computational overhead.Clinical Relevance: This work establishes that activity recognition may be used in conjunction with single-channel bladder event detection systems to distinguish between contractions and motion artifacts for reducing the incorrect classification of bladder events. This is relevant for emerging sensors that measure intravesical pressure alone or for data analysis of bladder pressure in ambulatory subjects that contain significant abdominal pressure artifacts.

Study on rock fracture mechanism and hydraulic fracturing propagation law of heterogeneous tight sandstone reservoir.

Hydraulic fracturing technology is an effective way to develop tight sandstone reservoirs with low porosity and permeability. The tight sandstone reservoir is heterogeneous and the heterogeneity characteristics has an important influence on fracture propagation. To investigate hydraulic fracture performance in heterogeneous tight reservoir, the X-ray diffraction experiments are carried out, the Weibull distribution method and finite element method are applied to establish the uniaxial compression model and the hydraulic fracture propagation model of heterogeneous tight sandstone. Meanwhile, the sensitivity of different heterogeneity characterization factors and the multi-fracture propagation mechanism during hydraulic fracture propagation is analyzed. The results indicate that the pressure transfer in the heterogeneous reservoir is non-uniform, showing a multi-point initiation fracture mode. For different heterogeneity characterization factors, the heterogeneity characteristics based on elastic modulus are the most sensitive. The multi-fracture propagation of heterogeneous tight sandstone reservoir is different from that of homogeneous reservoir, the fracture propagation morphology is more complex. With the increase of stress difference, the fracture propagation length increases. With the increase of injection rate, the fracture propagation length increases. With the increase of cluster spacing, the propagation length of multiple fractures tends to propagate evenly. This study clarifies the influence of heterogeneity on fracture propagation and provides some guidance for fracturing optimization of tight sandstone reservoirs.

Reduction in lower urinary tract mucosal microtrauma as an effect of reducing eyelet sizes of intermittent urinary catheters.

Intermittent catheterization (IC) utilizing conventional eyelets catheters (CECs) for bladder drainage has long been the standard of care. However, when the tissue of the lower urinary tract comes in close proximity to the eyelets, mucosal suction often occurs, resulting in microtrauma. This study investigates the impact of replacing conventional eyelets with a drainage zone featuring multiple micro-holes, distributing pressure over a larger area. Lower pressures limit the suction of surrounding tissue into these micro-holes, significantly reducing tissue microtrauma. Using an ex vivo model replicating the intra-abdominal pressure conditions of the bladder, the intra-catheter pressure was measured during drainage. When mucosal suction occurred, intra-catheter images were recorded. Subsequently affected tissue samples were investigated histologically. The negative pressure peaks caused by mucosal suction were found to be very high for the CECs, leading to exfoliation of the bladder urothelium and breakage of the urothelial barrier. However, a micro-hole zone catheter (MHZC) with a multi-eyelet drainage zone showed significantly lower pressure peaks, with over 4 times lower peak intensity, thus inducing far less extensive microtraumas. Limiting or even eliminating mucosal suction and resulting tissue microtrauma may contribute to safer catheterizations in vivo and increased patient comfort and compliance.