Positive Pressure Research Articles

Heterogeneous Treatment Effects of High-Frequency Oscillatory Ventilation for Acute Respiratory Distress Syndrome: A Post Hoc Analysis of the Oscillation for Acute Respiratory Distress Syndrome Treated Early (OSCILLATE) Trial.

We sought to evaluate whether different subgroups of adults with acute respiratory distress syndrome (ARDS) respond differently to high-frequency oscillatory ventilation (HFOV). The Oscillation for ARDS Treated Early (OSCILLATE) trial was a randomized controlled trial of HFOV vs. conventional ventilation that found an increased risk of in-hospital mortality (primary outcome) with HFOV. In a post hoc analysis, we applied three different approaches to evaluate heterogeneity of treatment effect for in-hospital mortality: 1) subgroup analyses based on baseline Pao2:Fio2 ratio and oxygenation index (OI); 2) a risk-based approach using a multivariable outcome prediction model; and 3) a clustering approach via multivariable latent class analysis. We used multivariable logistic regression models to assess for interaction. Thirty-nine ICUs, five countries. Five hundred forty-eight adults with moderate to severe ARDS. HFOV vs. conventional mechanical ventilation with low tidal volume and higher positive end-expiratory pressure. The effect of HFOV on in-hospital mortality was consistent across categories of Pao2:Fio2 ratio (adjusted odds ratio [aOR], 2.04; 95% CI, 1.32-3.17 and aOR, 1.16; 95% CI, 0.49-2.75 for groups with Pao2:Fio2 above or equal to 80, vs. below 80, respectively; interaction p = 0.23) and OI (aOR, 1.78; 95% CI, 0.67-4.70; aOR, 3.19; 95% CI, 1.44-7.09; aOR, 1.73; 95% CI, 0.82-3.65; and aOR, 1.33; 95% CI, 0.61-2.90 for quartiles of baseline OI, respectively; interaction p = 0.44). Point estimates for the effect of HFOV were consistent across risk categories (aOR, 2.44; 95% CI, 0.40-14.83; aOR, 1.69; 95% CI, 0.75-3.85; and aOR, 2.10; 95% CI, 0.59-7.54 for the lowest, moderate, and highest risk categories, respectively; interaction p = 0.32). Using a clustering approach, point estimates for HFOV were also consistent (cluster 1: aOR, 1.85; 95% CI, 1.15-3.00 and cluster 2: aOR, 1.75; 95% CI, 0.91-3.38; interaction p = 0.75). We did not identify heterogeneity in the effect of HFOV across different subgroups of patients with ARDS.

Continuously tunable negative pressure for engineering high-symmetry nanocrystalline phases

In this work, the phenomenon of strain induced by a mismatch in thermal expansion coefficients between a thin film and its substrate is harnessed in a new context, replacing the canonical planar support with a three-dimensional (3-D), nanoconfining scaffold in which we embed a material of interest. In this manner, we demonstrate a general approach to exert a continuously tunable, triaxial, tensile strain, defying the Poisson ratio of the embedded material and achieving the exotic condition of "negative pressure." This approach is hypothetically generalizable to materials of low modulus and high thermal expansion coefficient, and we use it here to achieve negative pressure in perovskite-phase CsPbI3 embedded within the cylindrical pores of anodic aluminum oxide membranes. Through controlled thermal hysteresis, the perovskite crystal structure can be continuously tuned toward higher symmetry when confined in a scaffold with pore size <40 nm, in contrast with the symmetry-reducing action of any other mechanical perturbation. We use this effect to control the octahedral rotation angle that is critical to the remarkable photovoltaic attributes of halide perovskites. Under hundreds of megapascals of apparent negative pressure, the bandgap tunability is observed to follow the same quantitative trend observed for hydrostatic positive pressure, exploring the negative pressure region and demonstrating the relative dominance of bond stretching effects over average octahedral rotation angle on electronic structure. This study reveals and quantifies the structural and electronic consequences of 3D tensile strain present by design and provides a framework for understanding adventitious strain present in all nanocomposite materials.

Effects of interfacial imperfections on nanoscale adhesive contact for layered medium

Depending on processing technologies and working conditions, imperfect bonding at the layer-substrate interface may occur, resulting in diverse mechanical responses compared to a perfectly bonded layer-substrate system. This study focuses on an imperfect interface under force-like conditions and incorporates it into a nanoscale adhesive contact model to explore the influences of interfacial imperfection on the adhesive contact behaviors of the layered medium. The adhesive contact model is formulated based on the Lennard-Jones (LJ) potential and the Hammaker summation method. The adhesive contact problem is addressed by solving the nonlinear surface gap equations between the contact bodies. The deformation within the gap equations, accounting for the influence of imperfections, is computed using the fast Fourier transform (FFT) algorithm. This study explores the influence of three stress jumping coefficients t1, t2 and t3, which quantitatively characterize the interfacial imperfection, and their coeffects with material parameters, including imperfection depth (layer thickness), adhesion work, and elastic modulus, on the adhesive contact behaviors of the layered medium. The findings underscore that the normal stress jumping coefficient t3 exerts the most significant impact, wherein a higher t3 value corresponds to a smaller adhesive force and a larger absolute contact approach, while tangential stress jumping coefficients t1 and t2 exhibit negligible influence. Decreasing t3 values correspond to varying interaction force-contact approach responses and contribute to alleviating contact stability in cases with large Tabor parameters. Interfacial imperfections manifest their influence by modifying the pressure-displacement response, with noticeable effects only within a specific imperfection depth range h¯<40. While the introduction of interfacial imperfections does not alter the fundamental impact of material parameters—such as imperfection depth, adhesion work ratios, and elastic modulus ratios—on adhesive force and contact approach, it does modify the magnitude of these effects. Furthermore, imperfections alter stress distribution, increasing maximal von Mises stress and causing stress concentration within the layer and at the interface. In summary, force-like imperfections reduce surface displacement, resulting in a smaller region of positive pressure and ultimately contributing to a larger adhesive force. However, this effect is accompanied by increased stress concentration at the imperfect interface. This heightened stress level poses a potential risk to the system's reliability.

Risk factors affecting the development of pneumothorax in patients followed up in intensive care with a diagnosis of COVID-19

BackgroundPneumothorax is a little known and reported complication of COVID-19. These patients have poorer general outcomes and greater respiratory support requirements, longer hospitalization times, and higher mortality rates. The purpose of this study was to determine which factors predict mortality in patients with tube thoracostomy diagnosed with COVID-19, admitted to the COVID-19 intensive care unit (ICU), and developing pneumothorax.MethodsThis respective, observational study was conducted in all COVID-19 ICUs at the Marmara University Pendik Training and Research Hospital, Türkiye. Patients admitted to the ICU with diagnoses of COVID-19 pneumonia and with chest tubes inserted due to pneumothorax were investigated retrospectively.ResultsOne hundred patients with tube thoracostomy were included in the study. Their median age was 68 (57–78), and 63% were men. The median follow-up time was 20 [10–29] days, and the median time from initial reverse transcriptase polymerase chain reaction (RT-PCR) results to tube thoracostomy was 17 [9–23] days. Initial RT-PCR results were positive in 90% of the patients, while 8% were negative, and 2% were unknown. Half the patients exhibited pulmonary involvement at thoracic computed tomography (CT) (n = 50), while 22 patients had COVID-19 reporting and data system (CO-RADS) scores of 5 (22%). Sixty-two patients underwent right tube thoracostomy, 24 left side placement, and 14 bilateral placement. The patients’ mean positive end expiratory pressure (PEEP) level was 10.31 (4.48) cm H2O, with a mean peak inspiratory pressure (PIP) level of 26.69 (5.95) cm H2O, a mean fraction of inspired oxygen (FiO2) level of 80.06 (21.11) %, a mean respiratory rate of 23.71 (5.62) breaths/min, and a mean high flow nasal cannula (HFNC) flow rate of 70 (8.17) L/min. Eighty-seven patients were intubated (87%), six used non-rebreathable reservoir masks, four HFNC, two non-invasive mechanical ventilation (NIV), and one a simple face mask. Comorbidity was present in 70 patients, 25 had no comorbidity, and the comorbidity status of five was unknown. Comorbidities included hypertension (38%), diabetes mellitus (23%), cardiovascular disease (12%), chronic obstructive pulmonary disease (5%), malignancy (3%), rheumatological diseases (3%), dementia (2%) and other diseases (9%). Twelve of the 100 patients survived. The median survival time was 20 (17.82–22.18) days, and the median 28-day overall survival rate was 29% (20-38%). The multivariate Cox proportional hazards model indicated that age over 68 (HR = 2.23 [95% CI: 1.39–3.56]; p = 0.001), oxygenation status other than by intubation (HR = 2.24 [95% CI: 1.11–4.52]; p = 0.024), and HCO3- below 22 compared with a normal range of 22 to 26 (HR = 1.95 [95% CI: 1.08–3.50]; p = 0.026) were risk factors associated with mortality in patients in the ICU.ConclusionsAge over 68, receipt of oxygenation other than by intubation, and HCO3- values lower than 22 in patients with COVID-19 pneumonia emerged as prognostic factors associated with mortality in terms of pneumothorax.

Reflections on timing of motherhood - a qualitative online study with women of reproductive age

BackgroundThe age of Danish women giving birth to their first child has risen throughout the last 50 years, and the number of women and men who are having their first child when they are at advanced maternal or paternal age is increasing worldwide. Postponing parenthood is not unique to Denmark, as the same pattern is seen especially in other European and Western countries. The aim of this study was in a social media setting to explore reflections on the timing of motherhood among Danish women of reproductive age who not yet had children.MethodThis study was a qualitative study based on three online focus groups on Facebook. Twenty-six women of reproductive age discussed the timing of motherhood for three days in January 2020. Data were analyzed using Systematic Text Condensation.ResultsThree main themes were identified: ‘Life before parenthood’, ‘To plan for a child’ and ‘A life without children’. Several external and internal conditions influence whether and if so when women consider becoming mothers. Regarding the biological capacity for having children, women compare themselves with their female relatives and friends and colleagues regarding the social norms surrounding motherhood. Women with no children often experience either positive or negative pressure from family, friends, and colleagues regarding when to have children.ConclusionSeveral internal and external considerations influence when and if women become mothers. Social surroundings such as family, friends, and colleagues have an impact on women’s reproductive considerations in terms of pressure to have children in the future. Danish women tend to compare their reproductive capacity to their female relatives and compare the social norms surrounding motherhood to their female friends. Women in this study were positive towards discussing the timing of motherhood with other women of reproductive age on social media.

A Prospective Randomised Comparative Study of Baska Mask and I-Gel for Airway Management in Elective Surgeries: Focus on Airway Sealing Pressure, Insertion Time, and Haemodynamic Response

Introduction: General anesthetic procedure requires a safe and open airway. Endotracheal intubation is the gold standard for airway management; it is being replaced by supraglottic airway devices because they are easy to introduce, better tolerated and results in a lesser haemodynamic response. As both the Baska mask and I-gel have a non-inflatable self-sealing mechanism, these two devices were compared in our study in terms of time taken for insertion, airway sealing pressure, the number of attempts, hemodynamic changes, and complications. Methods: A Prospective comparative study was conducted on 90 patients (45 in each group), aged 18-60 years, undergoing elective surgeries under general anesthesia at Tertiary care Hospital, Madurai. Patients were randomized into two groups using the computer generated statistical software STATA version14 (Texas, USA): Group B: Airway was secured by insertion of Baska mask. Group I: Airway was secured by insertion of I Gel. Following assessments were done to evaluate the SAD: Time taken to insert the device, airway sealing pressure, rate of successful insertion, number of attempts, Haemodynamic parameters, laryngopharyngeal morbidity. Data were analyzed using Student t-tests and chi-square tests, with p &lt; 0.05 considered significant. Results: The mean airway sealing pressure of the Baska mask (26.1+6.1 cmH2O) was significantly higher than that of the I-gel (23.1± 5.9 cmH2O) with a P value of 0.019 which was statistically significant. In our study the time taken to insert the device, for Baska mask it was 18.9+4.1 seconds and for the I gel it was 17.2±5.1 seconds with a P value of 0.089 which was statistically insignificant. In our study there was no statistical difference between Baska mask and I-gel groups in regards to hemodynamic changes (Heart rate and Mean arterial pressure). This may be due to the same stress response produced by the both devices. Conclusion: Baska mask is superior to I-gel in positive pressure ventilation under general anaesthesia for short surgical procedures with statistically significant higher airway sealing pressure though it has comparable time of insertion, haemodynamic changes and laryngopharyngeal morbidity.

Enhancing ICU Outcomes Through Intelligent Monitoring Systems: A Comparative Study on Ventilator-Associated Events.

Background: Using intelligent monitoring systems can potentially improve the identification and management of ventilator-associated events (VAEs). This single-center retrospective observational study evaluated the impact of implementing intelligent monitoring systems on the clinical outcomes of patients with VAEs in an ICU setting. Method: An intelligent VAE monitoring system was integrated into electronic medical records to continuously collect patient data and alert attending physicians when a ventilated patient met the criteria for a ventilator-associated condition, which was defined as an increase of at least three cm H2O in positive end expiratory pressure (PEEP), an increase of at least 0.20 in the fraction of inspired oxygen (FiO2), or the FiO2 being over baseline for at least two consecutive days. This study covered two phases, consisting of before using the intelligent monitoring system (2021-2022) and during its use (2023-2024). Results: The results showed that patients monitored with the intelligent system experienced earlier VAE detection (4.96 ± 1.86 vs. 7.77 ± 3.35 days, p < 0.001), fewer ventilator-associated condition (VAC) occurrences, and a shorter total duration of VACs. Additionally, the system significantly reduced ventilator days, antibiotic use, and 14-day mortality. Conclusions: Intelligent monitoring systems enhance VAE management, improve clinical outcomes, and provide valuable insights into the future of critical care medicine.

Identification of cytokine release syndrome and indicators of severity in retrospective databases among patients receiving immunotherapy.

Cytokine release syndrome (CRS) can occur following cancer immunotherapies, but is most often mild and of limited duration. International Classification of Diseases (ICD)-10 codes allowing identification of CRS were introduced in 2020 but may be underutilized. We evaluated the performance of a published claims-based algorithm to detect CRS (any grade) and high-grade CRS (HG, grades 2-5), as well as identified indicators of HG CRS in retrospective data. Adults with low-grade and HG CRS during an encounter coinciding with administrations of blinatumomab or chimeric antigen receptor-T therapy were identified in three types of retrospective databases (hospital chargemaster data, electronic health records, and administrative claims). The algorithm's sensitivity in detecting any CRS and HG CRS was reported. A least absolute shrinkage and selection operator (LASSO) regression model was developed to identify indicators of HG CRS. Performance of the model was evaluated using area under the curve (AUC). The sensitivity of the algorithm to detect any grade CRS ranged between 77%-100% and between 8%-80% for HG CRS, depending on the type of database. The LASSO model identified hypotension, positive pressure (including mechanical ventilation), tocilizumab, and vasopressors as indicators of HG CRS. AUC varied between 60% and 75%. The algorithm accurately detected any grade CRS for over three-quarters of instances, but was not as reliable for HG CRS. Results varied based on database attributes. Hypotension, vasopressors, positive pressure, and tocilizumab were associated with HG CRS and may be methodologically helpful signals of CRS severity in retrospective data.

Rapid-response, low-detection-limit, positive-negative air pressure sensing: GaN chips integrated with hydrophobic PDMS films

Despite the importance of positive and negative pressure sensing in numerous domains, the availability of a single sensing unit adept at handling this dual task remains highly limited. This study introduces a compact optical device capable of swiftly and precisely detecting positive and negative pressures ranging from −35 kPa to 35 kPa. The GaN chip, which serves as a core component of the device, is monolithically integrated with light-emitting and light-detecting elements. By combining a deformable PDMS film coated with a hydrophobic layer, the chip can respond to changes in optical reflectance induced by pressure fluctuations. The integrated sensing device has low detection limits of 4.3 Pa and −7.8 Pa and fast response times of 0.14 s and 0.22 s for positive and negative pressure variations, respectively. The device also demonstrates adaptability in capturing distinct human breathing patterns. The proposed device, characterized by its compactness, responsiveness, and ease of operation, holds promise for a variety of pressure-sensing applications.

Individualized positive end-expiratory pressure in laparoscopic surgery: a randomized controlled trial.

The reduction in functional residual capacity (FRC) is a significant pathological factor in the development of postoperative pulmonary complications. Appropriate positive end-expiratory pressure (PEEP) is critical to preserve FRC during mechanical ventilation. Our previous study suggests that using driving pressure-guided PEEP can reduce postoperative pulmonary complications. In this study, we hypothesize that individualized PEEP can increase immediate postoperative FRC and improve lung ventilation. This single-centered, randomized controlled trial included a total of 91 patients scheduled for laparoscopic surgery for colorectal carcinoma. Patients were randomly assigned to receive individualized PEEP guided by minimum driving pressure or a fixed PEEP of six cmH<inf>2</inf>O. The primary outcome was postoperative FRC. Secondary outcomes included the incidence of postoperative pulmonary complications, postoperative Oxygenation Index, alveolar-arterial oxygen tension difference (P<inf>A-a</inf>O<inf>2</inf>), intrapulmonary shunt (Q<inf>S</inf>/Q<inf>T</inf>), and Respiratory Index, as well as lung ventilation measured by electrical impedance tomography. The median value of PEEP in the individualized group was 14 cmH<inf>2</inf>O, with an interquartile range of 12-14 cmH<inf>2</inf>O. The postoperative FRC was significantly higher in the individualized PEEP group than that in the PEEP six cmH<inf>2</inf>O group (32.8 [12.8] vs. 25.0 [12.6] mL/kg, P=0.004). Patients receiving driving pressure-guided PEEP also had significantly higher Oxygenation Index, better ventilation distribution, and lower PA-aO<inf>2</inf>, Q<inf>S</inf>/Q<inf>T</inf>, and Respiratory Index. Driving pressure-guided PEEP can preserve postoperative FRC and provide better ventilation and oxygenation for patients undergoing laparoscopic colorectal surgery.

Liberation from Respiratory Support in Bronchopulmonary Dysplasia

To estimate the association between the mode of respiratory support administered at 36 weeks' post-menstrual age (PMA) with time-to-liberation from respiratory support (LRS) in infants with grade 2/3 bronchopulmonary dysplasia (BPD). Daily respiratory support data were abstracted for infants born <32 weeks' gestation with grade 2/3 BPD enrolled in the Children's Hospitals Neonatal Database between 2017 and 2022. The main exposure was the mode of respiratory support received at 36 weeks' PMA: high flow nasal cannula >2 L/min (HFNC), continuous positive airway pressure (CPAP), non-invasive positive pressure ventilation (NIPPV), or mechanical ventilation (MV). The primary outcome was time-to-LRS, defined as the PMA when infants weaned to nasal cannula <2 L/min or room air for >2 days. The independent association between the main exposure and time-to-LRS was estimated using restricted mean survival time analysis. Among 3,483 included infants from 41 centers, 17% received HFNC, 36% CPAP, 16% NIPPV, and 32% MV at 36 weeks' PMA. After censoring those who died (4.2%), survived with tracheostomy (7.6%), or were transferred to another facility (7.5%), the median (IQR) time-to-LRS differed between groups: HFNC 37 [37, 39]; CPAP 39 [37, 41] NIPPV 41[39, 45]; and MV 44 [40, 48] weeks' PMA (P<0.001). Across centers, a 10-fold difference in time-to-LRS was observed after adjustment for clinical risk factors. For infants with grade 2/3 BPD, the mode of respiratory support prescribed at 36 weeks' PMA and center of care were each associated with time-to-LRS independent of patient and clinical characteristics.

Noninvasive Positive Pressure Ventilation versus High-Flow Nasal Cannula for Chronic Obstructive Pulmonary Disease: An Updated Narrative Review.

Chronic obstructive pulmonary disease (COPD) is one of the most common clinical respiratory illnesses, defined by permanent pathological deterioration that leads to respiratory failure. Regarding COPD treatment, oxygen therapy is very important. Non-invasive positive pressure ventilation (NPPV) is a technique for non-invasive mechanical ventilation that enables patients to get positive pressure support without the need of an artificial airway. Instead, it merely employs the mask by covering the mouth and nose, or simply the nose of patients. NPPV has been shown to be beneficial for COPD patients experiencing respiratory failure. High-flow nasal cannula (HFNC) oxygen therapy shows some advantages, including the reduction of anatomical dead space, the prompt correction of low oxygen levels as well as the improvement of patients' tolerance. Owing to its continuous progress, ventilation technology strongly improves COPD treatment. In this study, the authors analyze the application of NPPV and HFNC in COPD so as to provide recommendations for mechanical ventilation treatment.

Impact of non-invasive ventilation on microbial colonisation patterns in preterm infants: a single-centre study.

The objective of this study is to assess the relationship between non-invasive ventilation (NIV) and the colonisation of oral and nasal microbiota in preterm infants within the neonatal intensive care unit (NICU). A prospective cohort study. The NICU of Zhejiang University Children's Hospital. Patients include preterm infants with a gestational age of 28-35 weeks, enrolled within the first 24 hours of life. Infants were categorised based on respiratory support: NIV, which included nasal continuous positive airway pressure, nasal intermittent positive pressure ventilation or high-flow nasal cannula; and no respiratory support, defined as room air or low-flow nasal cannula at ≤2 L/min. The primary outcome was the colonisation of oral and nasal microbiota at 5 days post birth, measured by colony-forming units per millilitre (CFU/mL), with colonisation defined as bacterial growth >103 CFU/mL. The study included 100 preterm infants, with 50 in each group. Nasal microbial colonisation was observed in 56% (28/50) of the NIV group, significantly higher than the 28% in the no respiratory support group. No significant differences were found in oral colonisation. Adjusted binary logistic regression showed an association between NIV and increased risk of nasal colonisation (adjusted OR=2.91, 95% CI 1.12 to 7.58, p=0.028). NIV in preterm infants was linked to a higher risk of nasal microbial colonisation. This finding suggests the need for further research and consideration of infection control strategies in the NICU.

Adaptive servo-ventilation for the treatment of intrathecal baclofen-induced central sleep apnea: A case report.

Baclofen is a common muscle relaxant agent used in a number of neurological disorders acting at central level and potentially causing adverse respiratory events, still largely unknown at therapeutic doses. We present the case of a young woman with spastic tetraparesis secondary to perinatal asphyxia treated with a standard dose of intrathecal baclofen who developed nocturnal symptoms, somnolence and memory loss during the day. Nocturnal cardio-respiratory sleep monitoring showed a high number of central sleep apneas (CSA). The patient was adapted and treated with a positive air pressure device, Adaptative Servo-Ventilator, specific designed to treat CSA particularly in patients with heart failure. The treatment was well tolerated and within few days CSA was reversed. The patient reported a feeling of restful sleep and disappearance of morning tiredness. The efficacy of the treatment was verified with nocturnal cardio-respiratory monitoring after 2 months and complete resolution of all symptoms was also confirmed.

Transvenous phrenic nerve stimulation reduces diaphragm injury during controlled mechanical ventilation in a preclinical model of ARDS.

Patients with acute respiratory distress syndrome (ARDS) require periods of deep sedation and mechanical ventilation, leading to diaphragm dysfunction. Our study seeks to determine whether the combination of temporary transvenous diaphragm neurostimulation (TTDN) and mechanical ventilation changes the degree of diaphragm injury and cytokines concentration in a preclinical ARDS model. Moderate ARDS was induced in pigs using oleic acid, followed by ventilation for 12 h post-injury with volume-control at 8 mL/kg, positive end-expiratory pressure (PEEP) 5 cmH2O, respiratory rate and [Formula: see text] set to achieve normal arterial blood gases. Two groups received TTDN: every second breath (MV + TTDN50%, n = 6) or every breath (MV + TTDN100%, n = 6). One group received ventilation only (MV, n = 6). Full-thickness diaphragm and quadricep muscle biopsies were taken at study end. Samples were fixed and stained with hematoxylin and eosin and a point-counting technique was applied to calculate abnormal muscle area fraction. Cytokine concentrations were measured in homogenized tissue using porcine-specific enzyme-linked immunosorbent assay (ELISA) and compared with serum samples. Percentage of abnormal diaphragm tissue was different between MV [8.1% (6.0-8.8)] versus MV + TTDN50% [3.4% (2.1-4.8)], P = 0.010 and MV versus MV + TTDN100% [3.1% (2.5-4.0)], P = 0.005. Percentage of abnormal quadriceps tissue was not different between groups. Cytokine concentration patterns in diaphragm samples were different between all groups (P < 0.001) and the interaction between TTDN application and resultant cytokine concentration pattern was significant (P = 0.025). TTDN, delivered in synchrony with mechanical ventilation, mitigated diaphragm injury, as evidenced by less abnormal tissue in the diaphragm samples, in pigs with oleic acid-induced ARDS and is an exciting tool for lung and diaphragm-protective ventilation.NEW & NOTEWORTHY This study adds to our understanding of applying transvenous diaphragm neurostimulation synchronously with mechanical ventilation by examining its effects on diaphragm muscle injury and cytokine concentration patterns in pigs with acute respiratory distress syndrome (ARDS). We observed that using this therapy for 12 h post lung injury mitigated ventilator-induced diaphragm injury and changed the pattern of cytokine concentration measured in diaphragm tissue. These findings suggest that transvenous diaphragm neurostimulation is an exciting tool for lung and diaphragm protective ventilation.

Mutant Huntingtin Drives Development of an Advantageous Brain Early in Life: Evidence in Support of Antagonistic Pleiotropy.

Huntington's disease (HD) is a neurodegenerative disease caused by a triplet repeat expansion within the gene huntingtin (HTT). Antagonistic pleiotropy is a theory of aging that posits that some genes, facilitating individual fitness early in life through adaptive evolutionary changes, also augment detrimental aging-related processes. Antagonistic pleiotropy theory may explain a positive evolutionary pressure toward functionally advantageous brain development that is vulnerable to rapid degeneration. The current study investigated antagonistic pleiotropy in HD using a years-to-onset paradigm in a unique sample of children and young adults at risk for HD. Cognitive, behavioral, motor, and brain structural measures from premanifest gene-expanded (n = 79) and gene nonexpanded (n = 112) participants (6-21 years) in the Kids-HD study were examined. All measures in the gene-expanded group were modeled using a mixed-effects regression approach to assess years-to-onset-based changes while controlling for normal growth. Simultaneously, structure-function associations were also examined. Decades from motor onset, gene-expanded participants showed significantly better cognitive, behavioral, and motor scores versus gene nonexpanded controls, along with larger cerebral volumes and cortical features. After this initial peak, a prolonged deterioration was observed in both functional and structural measures. Far from onset, brain measures were positively correlated with functional measures, supporting the view that functional advantages were mediated by structural differences. Mutant HTT may drive the development of a larger than normal brain that subserves superior early-life function. These findings support the antagonistic pleiotropy theory of HTT in HD, where this gene drives early advantage followed by accelerated aging processes. ANN NEUROL 2024;96:1006-1019.

Optimizing perioperative lung protection strategies for reducing postoperative respiratory complications in pediatric patients: a narrative review.

Despite significant advancements in the safe delivery of anesthesia and improvements in surgical techniques, postoperative respiratory complications (PRCs) remain a serious concern. PRCs can lead to increased length of hospital stay, worsened patient outcomes, and higher hospital and postoperative costs. Perioperative lung injury and PRCs are more common in children than in adults owing to children's unique physiology and anatomical characteristics. Studies have shown that lung-protective ventilation (LPV) strategies can improve lung function and minimize the risk of PRCs in adults. However, individualized LPV in children remains underexplored. This narrative review provides an overview of the various perioperative pulmonary protection strategies and their effect on pediatric PRCs. We searched PubMed for articles published from 2000 to 2024, setting our inclusion criteria to include studies that involved pediatric patients, addressed LPV strategies, and reported data on PRCs. Non-English language studies, case reports, editorials, conference abstracts, and non-full text published literatures were excluded. We utilized the following keyword strategy: (((lung protective ventilation) OR (PEEP)) OR (recruitment maneuver)) OR (low tidal volume) AND (2000:2024[pdat])) AND (pediatric) filters. In total, 1,106 articles were retrieved, with only 23 being deemed relevant to the review. Data extraction and analysis were conducted by two independent researchers to ensure accuracy and consistency. We conducted descriptive statistical analysis for quantitative data and thematic analysis for qualitative data. The key content are an overview of risk factors for PRCs in children including the patients themselves, anesthesia, and surgery, as well as the effectiveness of LPV strategies in pediatric surgery, including low tidal volume (TV), positive end-expiratory pressure (PEEP), ultrasound-guided pulmonary recruitment maneuver (RM), low fraction of inspired oxygen (FiO2), pressure-controlled ventilation (PCV), as well as fluids, pain, and high-flow nasal cannula (HFNC). We found that age, mechanical ventilation with general anesthesia, and thoracic surgery increased the risk of PRCs in children. The application of LPV strategies in pediatric surgery had positive effect, including low TV combined with titrated PEEP, age- and physiologically appropriate FiO2, ultrasound-guided RM, target directed fluid infusion, adequate analgesia, and the use of HFNC in special circumstances. However, we also found that the application of LPV has certain potential risks and therefore needs to be implemented according to the patient's actual age and physical condition. Perioperative LPV strategies show potential benefits in reducing lung injury and PRCs in pediatric patients. These strategies, including low TV, appropriate individualized PEEP, lung RM, and avoidance of high FiO2, appear to be effective methods for protecting lung function in pediatric patients. Additionally, perioperative fluid management and effective pain control are crucial for lung protection. The emerging use of HFNC therapy shows promise, but further research is needed to fully understand its benefits.

Simplicity is the Ultimate Sophistication – Role of a Catheter Mount and a Laparoscopic Washer in the Removal of an Intrabronchial Foreign Body

ABSTRACT Foreign body retrieval from the airway can be quite challenging due to various concerns such as sharing of the airway between the anesthesiologist and pulmonologist, reduced functional residual capacity, ventilation-perfusion mismatch, etc. Flexible fiberoptic bronchoscopy through supraglottic airway devices has been preferred over rigid bronchoscopy for foreign body retrieval as there is better control of the airway, provides access to distal airways, and allows bronchoalveolar lavage. However, intermittent pauses in positive pressure ventilation could be deleterious in patients with reduced functional residual capacity. The incorporation of a catheter mount with a laparoscopy washer in the suction port will enable the simultaneous execution of ventilation and foreign body extraction. We have successfully used the above technique in the retrieval of an intrabronchial foreign body from a 65-year-old obese man.

Mechanisms and characteristics of sand seepage deformation under groundwater level fluctuation scenarios

Seepage deformation in sand results from complex water-soil interactions, which are the primary reasons of sand surface collapse, as well as instability and deformation in dam foundations, building foundations, and slopes. Frequent fluctuations in groundwater levels cause changes in the direction, velocity, and pore water pressure of groundwater within the sand. Further research is essential to fully understand the characteristics and mechanisms of sand seepage deformation under varying groundwater conditions. In this study, natural undisturbed sand samples were collected. Laboratory seepage deformation tests were conducted to simulate continuous rises and falls in groundwater levels, exploring the response characteristics of internal erosion and hydraulic behavior of the sand under varying groundwater flow rates and directions. The results show that: As groundwater flow rate increases, the sand undergoes multiple episodes of seepage deformation, which includes the processes of structural stability, seepage deformation, and seepage failure. Initially, the hydraulic gradient for seepage deformation is small, and the particles carried by seepage are small. With a further increase in groundwater flow velocity, the hydraulic gradient rises, larger sand particles are migrated by seepage, and seepage failure may eventually occur. When the karst groundwater level is lower than the elevation of the sand bottom (H2 < z2) and the sand bottom is in a negative pressure state, the hydraulic gradient of seepage deformation is usually smaller than that observed in the other two states of positive pressure. In these cases, pore water pressure exerts an upward buoyant force, while in the negative pressure state, the pore water pressure transforms into downward suction. This downward suction aligns with the direction of gravitational forces and downward seepage force acting on the sand, making seepage deformation of the sand more likely. Sands with greater unevenness, finer particle, and lower density are more prone to seepage deformation but failure at different hydraulic gradients.

Numerical simulation and mechanistic model study of gas pocket distribution characteristics in a centrifugal impeller

The formation and extension of the gas pocket in the impeller can lead to the rapid deterioration or even failure of the centrifugal pump's two-phase pressurization. It is difficult to directly measure the characteristic parameters of the gas pocket in the high-speed rotating impeller, such as the void fraction, by experimental methods. In this paper, the two-phase performance of the centrifugal pump is studied by numerical simulation and validated by the experiment. The positive pressure gradient at the end of the blade pressure surface is the main reason why the centrifugal pump can boost at high inlet gas volume fraction (IGVF). As the IGVF increases, both the length and thickness of the gas pocket gradually increase. The head coefficient of the pump has an approximately quadratic relationship with the void fraction in the impeller. The mechanism model of the gas pocket flow is established by the force analysis of the gas pocket and its downstream single bubble in the impeller channel. The model can effectively predict the extension position of the gas pocket and the void fraction in the centrifugal impeller and is validated by numerical simulation.