Positive Pressure Research Articles

Effectiveness of TheraPEP Versus Conventional Breathing Techniques in Managing Acute COPD Exacerbations

Background: Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality worldwide, often complicated by acute exacerbations that impair lung function and quality of life. Effective airway clearance techniques are essential in managing exacerbations, but the comparative effectiveness of different methods remains unclear. This study aimed to evaluate the short-term effectiveness of TheraPEP, a positive expiratory pressure (PEP) device, versus the Active Cycle of Breathing Technique (ACBT) in managing acute COPD exacerbations. Methods: A randomized controlled trial (RCT) was conducted with 60 patients (≥40 years) admitted with acute exacerbations of COPD. Participants were randomly assigned to either the TheraPEP group (n=30) or the ACBT group (n=30). Each group received three daily sessions of their assigned therapy throughout their hospital stay. Primary outcomes included dyspnea, measured by the modified Borg Dyspnea Scale, and secondary outcomes included sputum clearance, lung function (FEV1, FVC, and FEV1/FVC ratio), oxygen saturation (SpO₂), and quality of life, measured by the Breathlessness, Cough, and Sputum Scale (BCSS). Data were collected at baseline, discharge, and 14-day follow-up. A two-way repeated-measures ANOVA was used to examine changes in dyspnea, lung function, sputum clearance, SpO₂, and BCSS scores over time (baseline, discharge, and 14-day follow-up) within and between groups. The main effects of time (within-subject factor) and group (between-subject factor) were assessed, along with the interaction effects (time × group). Results: Both groups demonstrated significant improvements in dyspnea, lung function, and quality of life from baseline to discharge and follow-up. However, the TheraPEP group showed significantly greater improvements in sputum clearance (p=0.01), oxygen saturation (p=0.03), and BCSS scores (p=0.03) compared to the ACBT group. No significant between-group differences were found for FEV1, FVC, or FEV1/FVC ratio (p > 0.05). Conclusions: Both TheraPEP and ACBT are effective in managing acute COPD exacerbations, but TheraPEP offers additional benefits in terms of sputum clearance and oxygenation. These findings suggest that TheraPEP may be more suitable for patients with severe mucus hypersecretion. Further research is warranted to assess the long-term effects of these therapies on COPD progression and patient outcomes.

Molecular Dynamics Study on the Storage of Carbon Dioxide in Single-Walled Carbon Nanotubes at Low Pressures.

The storage of carbon dioxide (CO2) in single-walled carbon nanotubes was studied with molecular dynamics simulation. The influences of the temperature, system average density, and nanotube size on the CO2 pressure, density distribution, and intermolecular forces were investigated. Multilayer adsorption inside nanotubes was observed as average density increases at lower pressures, which is desirable in industry. Meanwhile, a nanobubble was gradually formed in the center of the nanotube, and the system with the nanobubble was stabilized by the balance between the positive Laplace pressure and the negative liquid pressure when the size of the nanobubble was higher than the critical size. The adsorption effect of the nanotube wall leads to high local condensed density near the wall and stronger intermolecular repulsion, while Laplace pressure results in a low local condensed density in the adsorbed CO2 near the bubble interface and stronger intermolecular attraction. The stretching effect that originates from the intermolecular force dominated by attraction in the condensed phase leads to low pressure. At the critical nanobubble size, a higher CO2 average density can be achieved by lowering the temperature and increasing the nanotube radius or length. When the adsorption impact of the nanotube wall on bubble destabilization becomes negligible as the adsorption layer thickens, further increasing the nanotube radius leads to limited increase of the average density at the critical nanobubble size. The simulation of a graphene-sealed nanotube confirmed the formation of a vapor nanobubble under more realistic conditions. This work provides insights into utilizing carbon nanotubes as a material for CO2 capture with multilayer adsorption at lower pressures.

EVALUATION OF POSTOPERATIVE AIRWAY RELATED ADVERSE EFFECTS BY USING INTRACUFF DEXAMETHASONE VERSUS INTRACUFF ALKALINISED LIGNOCAINE - RANDOMISED DOUBLE BLIND CONTROLLED STUDY

Background Securing airway with ETT is the gold standard for General anesthesia(GA).This method confers the protection of airway from aspiration of gastric contents and facilitates positive pressure ventilation. However, post-intubation airway-related adverse effects are known to be caused by endotracheal intubation like postoperative coughing on the tube, restlessness, hoarseness and sore throat. Therefore this study was undertaken to reduce post intubation complications. ObjectiveThestudy was conducted to compare intracuff dexamethasone and intracuff alkalinised lignocaine with respect to postoperative cough, hoarseness and sore throat scores. Methods A randomized double blind study was conducted in 200 patients of ASA I,II,III and age between 18 to 60 yrs undergoing surgeries under GA for more than 2 hours, Patients who need nasogastric tube or throat pack were excluded from study. A computer generated randomisation with double blind technique was used to distribute them into Group L and Group D 100 each. In Group L, ETT cuff was inflated with 2ml of 2% lignocaine +2-3ml of 7.5% Sodium bicarbonate and in Group D cuff was inflated with 2ml of dexamethasone + 2-3ml of Normal saline. Intracuff pressure was monitored throughout the surgery and was maintained below 28 cm H2O. ResultsThe severity of cough and hoarseness was found higher in group D at 2 hours which was statistically significant (P< 0.05). However, there was no significant difference at 8hrs,16hrs and 24hrs in both the groups. Conclusion We conclude that post operative airway related adverse effects are less when cuff was inflated with alkalinized lignocaine as compared to dexamethasone as liquid media.

Investigation of the energy release characteristics and damage of thermobaric explosive under unconstrained conditions

To investigate the energetic release attributes and damage potential of a specific thermobaric explosive at atmospheric pressure, we had employed a pressure testing system, high-speed camera system, and thermal imager to elucidate the impact of explosive mass on the energetic release characteristics. Our findings underscored that thermobaric explosive can significantly enhance the after-burning effect. We noted a discernible positive relationship among the magnitude of the explosive force, post-detonation combustion effects, and the inherent quality of the given explosive. In addition, the resultant overpressure from the shockwave, positive pressure-area impulse, and the duration of the positive pressure, all markedly exceeded those produced by TNT, exhibiting increases of 38.9 %, 51.48 %, and 7 %, respectively. To quantify their explosive potency, empirical formulae were derived to account for the shock wave parameters of thermobaric explosive. Under equivalent mass conditions, the peak thermal radiation flux per unit area from thermobaric explosive substantially exceeded that of TNT. When the PROBIT (probability unit) model and the overpressure-impulse criteria were utilized to ascertain the damage potential of the respective explosives on human targets and structures, it emerged that TBX imparted superior destructive effects. This analysis underpinned the foundational assessment concerning the blast hazard presented by TBX.

Application of placing the anterior end of endotracheal tube at the glottis in laryngeal mask airway positive ventilation during general anesthesia: A prospective, randomized, controlled trial.

Glottic contraction and closure causes ventilation obstruction and laryngeal mask airway (LMA) leakage during positive pressure ventilation using LMA. This study aimed to assess the effect of placing the anterior end of the endotracheal tube (ET) at the glottis through the LMA ventilation conduit on treating LMA leakage following glottic contraction and closure. In this prospective, randomized, controlled trial, patients with non-minor surgery using LMA ventilation were randomly allocated to the i-gel group (group L) and the i-gel combined with ET group (group LE). The tip of ET was placed 2 cm under glottis guided by fiberoptic bronchoscope through i-gel ventilation conduit in group LE. The perioperative incidence of i-gel leakage, the changes of systolic blood pressure (SBP) and heart rate (HR) following artificial airway insertion, and adverse events were recorded. Perioperative i-gel leakage was observed in 7 of 48 patients (14.6%) in group L and 1 of 49 patients (2.0%) in group LE. There was significant difference in the incidence of leakage between the 2 groups (P = .031). SBP and HR after ET insertion in group LE increased significantly compared to those in group L (P < .05/5). The values of both SBP and HR after ET insertion did not exceed the basic values in group LE (P > .05/4). There were no significant differences in the incidence and severity of postoperative sore pain and hoarseness, cough during i-gel and ET removal between the 2 groups (P > .05). Placing the anterior end of ET at the glottis reduced LMA air leakage related to glottic contraction and closure in non-minor surgery. The ET placing had low stress response and did not significantly increase postoperative complications.

Effectiveness of a Novel Feeding Algorithm for Oral Feeding Transition of Infants Born Prematurely.

Feeding skill acquisition is commonly a limiting factor determining when an infant born prematurely can be discharged. This study aimed to determine if the addition of a novel feeding progression algorithm (combination of objective data from a suck measurement device and slow flow/low variability nipples) to current neonatal intensive care unit (NICU) standards could decrease feeding-related length of stay (primary outcome). We hypothesized that by timing the initiation of oral feedings to coincide with adequate sensory-motor skill development, feeding-related length of stay may be decreased. This was a prospective intervention study, with a historical control cohort, of infants born less than 30weeks' gestational age without comorbidities affecting feeding skill acquisition at a Regional Level III-S NICU at a women and infant's hospital in Louisiana. A novel feeding progression algorithm utilized objective assessment of sucking to determine progression in nipple flow rates with slow flow/low variability nipples (flow rates from 0 to 9 mL/min) for infants receiving intervention (n=18). Thirty-six controls who did not receive the feeding progression algorithm were identified via electronic medical record retrospective chart review. Eighteen completed the study. Compared to the control group, infants receiving feeding interventions had delayed sequencing initiation, extended time between initially off positive pressure ventilation and initiation of sequencing, and decreased feeding-related length of stay, with similar total length of stay. This study adds to existing research supporting the effectiveness of novel feeding progression algorithms and interventions to support the health and outcomes of infants born prematurely. Future research should focus on implementation studies for feeding progression algorithm integration into standard NICU care.

Intubation and Mechanical Ventilation in Patients with Acute Pulmonary Embolism: A Scoping Review.

High-risk acute pulmonary embolism (PE) is associated with significant mortality and may require emergency endotracheal intubation and mechanical ventilation. Intubation and ventilation are thought to exacerbate cardiorespiratory instability. Our purpose was to conduct a systematic literature review to identify studies investigating peri-intubation events in acute PE. A systematic search of Medline, Embase, Web of Science, Cumulative Index to Nursing and Allied Health Literature, and Cochrane Library was performed. Results were screened by two independent observers. Studies reporting on intubation and positive pressure ventilation in acute PE patients were included. The primary outcome was adverse events during the peri-intubation period. Data was synthesized and an assessment of risk of bias was conducted. The review was registered on PROSPERO (CRD42023444483). 4100 unique articles were screened. Three retrospective studies comprising 104 patients with acute PE met criteria and were included. Peri-intubation, hemodynamic collapse was observed in 19%-28% of cases. Patients with hemodynamic collapse exhibited higher rates of echocardiographic RV dysfunction. Peri-intubation adverse events are common in patients with acute PE. Current evidence is limited and highlights the need for further research to optimize management of respiratory failure in acute PE and patient selection for intubation to improve patient outcomes.

Analysis of dynamic characteristics and influencing factors of CO2 low-permeability coal reservoir sequestration

ABSTRACT Abandoned coal seams can be an important carrier for CO2 geological storage. Considering the gas seepage-diffusion and physical adsorption coupling characteristics in the process of CO2 adsorption and storage in coal and rock, a two-dimensional model of coupled flow-solidity for geological storage of CO2 in low-permeability reservoir with double voids was established by introducing the Zhang Hongbin model algorithm and adding the Klinkenberg effect and the compression effect of the rock skeleton in coal reservoirs in the controlling equation for rock deformation. The coupled flow-solid model was solved by using the PDE equation of COMSOL Multiphics program, and the simulation results difference between the new model and the traditional model in terms of sequestration dynamics were compared. The dynamic characteristic of reservoir gas pressure, formation stress, permeability and sequestration density in the process of CO2 geologic sequestration and injection were analyzed, and the influences of injection pressure and injection well diameter on the amount of CO2 sequestration were explored. The results show that the new model is more reasonable for calculating reservoir gas pressure and permeability compared with the Palmer-Mansoori model (PM model), and can simulate the free-state seepage movement of CO2 in the fracture system as well as its physical adsorption process compared with the single-heavy pore medium model. With continuous CO2 injection, the maximum sequestration density was raised to a limit value of about 1000 kg/m3 after 1 year. The date of reaching the limit of the sequestration volume was advanced by about 45 d when the positive pressure of the injected gas was increased from 10 kPa to 50 kPa. This model can reproduce the main parameters including, when affecting the effect, and realize the calculation of parameters such as CO2 density reaching the limit value, sealing limit day, sealing limit amount, which can provide a theoretical basis for further deep understanding of CO2 geological sealing law and scientific development of gas injection scheme.

Positive end-expiratory pressure and emergence preoxygenation after bariatric surgery: A randomised controlled trial on postoperative oxygenation.

Positive end-expiratory pressure (PEEP) is important to increase lung volume and counteract airway closure during anaesthesia, especially in obese patients. However, maintaining PEEP during emergence preoxygenation might increase postoperative atelectasis by allowing susceptible lung areas to be filled with highly absorbable oxygen that gets entrapped when small airways collapse due to the sudden loss of PEEP at extubation. This study aimed to test the hypothesis that withdrawing PEEP just before emergence preoxygenation would better maintain postoperative oxygenation. Prospective, randomised controlled trial. Single centre secondary hospital in Sweden between December 2019 and January 2023. A total of 60 patients, with body mass index between 35 and 50 kg m -2 , undergoing laparoscopic bariatric surgery. Intraoperative ventilation was the same for all patients with a fixed PEEP of 12 or 14 cmH 2 O depending on body mass index. No recruitment manoeuvres were used. After surgery, patients were allocated to maintained PEEP or zero PEEP during emergence preoxygenation. The primary outcome was change in oxygenation from before awakening to 45 min postoperatively as measured by estimated venous admixture calculated from arterial blood gases. Both groups had impaired oxygenation postoperatively; in the group with PEEP maintained during awakening, estimated venous admixture increased by mean 9.1%, and for the group with zero PEEP during awakening, estimated venous admixture increased by mean 10.6%, difference -1.5% (95% confidence interval -4.6 to 1.7%), P = 0.354. Throughout anaesthesia, both groups exhibited low driving pressures and superior oxygenation compared with the awake state. Withdrawing PEEP before emergence preoxygenation, did not alter early postoperative oxygenation in obese patients undergoing laparoscopic bariatric surgery. Intraoperative oxygenation was excellent despite using fixed PEEP and no recruitment manoeuvres, but deteriorated after extubation, indicating a need for future studies aimed at improving the emergence procedure. www.clinicaltrials.gov , NCT04150276. Registration date: 4 November 2019. Principal investigator: Erland Östberg.

Impact of airway closure and lung collapse on inhaled nitric oxide effect in acute lung injury: an experimental study

BackgroundEfficacy of inhaled therapy such as Nitric Oxide (iNO) during mechanical ventilation may depend on airway patency. We hypothesized that airway closure and lung collapse, countered by positive end-expiratory pressure (PEEP), influence iNO efficacy. This could support the role of an adequate PEEP titration for inhalation therapy. The main aim of this study was to assess the effect of iNO with PEEP set above or below the airway opening pressure (AOP) generated by airway closure, on hemodynamics and gas exchange in swine models of acute respiratory distress syndrome. Fourteen pigs randomly underwent either bilateral or asymmetrical two-hit model of lung injury. Airway closure and lung collapse were measured with electrical impedance tomography as well as ventilation/perfusion ratio (V/Q). After AOP detection, the effect of iNO (10ppm) was studied with PEEP set randomly above or below regional AOP. Respiratory mechanics, hemodynamics, and gas-exchange were recorded.ResultsAll pigs presented airway closure (AOP > 0.5cmH2O) after injury. In bilateral injury, iNO was associated with an improved mean pulmonary pressure from 49 ± 8 to 42 ± 7mmHg; (p = 0.003), and ventilation/perfusion matching, caused by a reduction in pixels with low V/Q and shunt from 16%[IQR:13–19] to 9%[IQR:4–12] (p = 0.03) only at PEEP set above AOP. iNO had no effect on hemodynamics or gas exchange for PEEP below AOP (low V/Q 25%[IQR:16–30] to 23%[IQR:14–27]; p = 0.68). In asymmetrical injury, iNO improved pulmonary hemodynamics and ventilation/perfusion matching independently from the PEEP set. iNO was associated with improved oxygenation in all cases.ConclusionsIn an animal model of bilateral lung injury, PEEP level relative to AOP markedly influences iNO efficacy on pulmonary hemodynamics and ventilation/perfusion match, independently of oxygenation.

Whole genome characteristics of hedgehog coronaviruses from Poland and analysis of the evolution of the Spike protein for its interspecies transmission potential

BackgroundThe hedgehogs have been recently identified as possible reservoir of Middle East respiratory syndrome coronavirus like (MERS-CoV-like). These viruses were classified as a distinct Betacoronavirus erinacei (BCoV-Eri) species within the MerBCoV-Eriirus subgenus. As coronaviruses are known for their ability to jump between different hosts, including humans, this can pose a particular threat to people in direct contact with hedgehogs, such as those working at animal asylums. Our previous studies have shown the presence of BCoV-Eri strains in animals collected in the wildlife rehabilitation centre. This study aimed to investigate the presence of CoV in subsequent hedgehogs collected from the urban area of Poland and their molecular characteristics.ResultsMonitoring for the presence of coronavirus infection in hedgehogs revealed five positive individuals. The presence of BCoV-Eri was found in a total of 20% of animals tested. Our analyses revealed no correlation between CoVs positivity and animal health conditions but a higher probability of such infection in juveniles and females. The whole genome of two Polish Hedgehog coronavirus 1 strains were sequenced and compared with available counterparts from European and Asian countries. Phylogenetic analysis showed that both CoV strains formed common cluster with other similar MerBCoV-Eriirus, but they were also found to be genetically variable and most changes in the S protein were identified. Our analysis revealed that some S protein sites of the Hedgehog coronavirus 1 strains evolved under positive selection pressure and of five such sites, three are in the S1 region while the other two in the S2 region of the Spike.ConclusionsBCoV-Eri is to some extent prevalent in wildlife asylums in Poland. Given that the S protein of BCoVs-Eri is highly variable and that some sites of this protein evolve under positive selection pressure, these strains could potentially acquire a favourable feature for cross-species transmission. Consequently, the threat to humans working in such asylums is particularly high. Adequate biosecurity safeguards, but also human awareness of such risks, are therefore essential.

Pediatric Resuscitation Skill of Bag-Tube Manual Ventilation: Developing and Using a Mobile Simulation Program to Assess Competency of a Multiprofessional PICU Team.

To assess the skill of bag-tube manual ventilation with the flow-inflating bag in multiprofessional PICU team members using a mobile simulation unit. Prospective observational study from January 2022 to April 2022. In situ mobile simulation using the flow-inflating bag in an academic PICU. Multiprofessional PICU team members including nurses, respiratory therapists, nurse practitioners, fellows, and attendings. None. We enrolled 129 participants who twice completed 1-minute tasks performing bag-tube manual ventilation with a flow-inflating bag. Sessions were video recorded; four could not be analyzed. Only 30% of participants reported being very to extremely confident, and the majority (62%) reported infrequent skill performance. Task success was defined as achieving target pressure ranges during 80% of the delivered breaths, respiratory rate (RR) of 25-35 breaths/min, and successful pop-off valve engagement. Only five of 129 participants (4%) achieved successful ventilation as defined. Overall, participants were more likely to deliver lower pressures and faster rate. Maintaining target positive end-expiratory pressure (PEEP) was least likely to be achieved (19% success), followed by RR (52%), pop-off valve (64%), then peak inspiratory pressure (71%). Nurses were less likely to achieve target pressures compared with all other professions. Multiprofessional PICU team members have highly variable self-confidence with bag-tube manual ventilation using a flow-inflating bag. Observed performance demonstrates rare success with achieving targeted ventilation parameters, in particular maintenance of PEEP. Future research should focus on developing mobile simulation units to facilitate profession-specific, real-time coaching to teach high-quality manual ventilation that can be translated to the bedside.

Wall sandwich panels with steel facings and PUR foam core under transverse loading: Experimental testing and numerical model calibration

Light weight panels are largely used for the envelope (wall assembly, roofing system) of different kind of buildings. Under extreme loading conditions, like external explosions, the walls may suffer extensive damage, under either positive or negative pressures. The study presented in the paper describes the results obtained on wall sandwich panels tested for transverse loading until complete failure. The panels are arranged as single span systems supported on side rails and loaded at the mid-span. After a quasi-linear response, the maximum bending capacity is reached. At this point, the panels have a sudden drop in capacity, associated with the rapid wrinkling of the face in compression. If the end fasteners have adequate resistance, catenary stage develops, and the ultimate capacity can be significantly higher than the peak bending capacity. Flexibility of the lateral restraints significantly influence the initiation of catenary action and the ultimate capacity of sandwich panels. Numerical models were calibrated using the structural analysis and design program SAP2000. This may allow professionals to integrate more quickly the wall models into the structural design even for extreme loading conditions.

Cooperative folding as a molecular switch in an evolved antibody binder

Designing proteins with tunable activities from easily accessible external cues remains a biotechnological challenge. Here, we set out to create a small antibody-binding domain equipped with a molecular switch inspired by the allosteric response to calcium seen in naturally derived proteins like calmodulin. We have focused on one of the three domains of Protein G that show inherent affinity to antibodies. By combining a semi-rational protein design with directed evolution, we engineered novel variants containing a calcium-binding loop rendering the inherent antibody affinity calcium-dependent. The evolved variants resulted from a designed selection strategy subjecting them to negative and positive selection pressures focused on conditional antibody-binding. Hence, these variants contained molecular “on/off” switches, controlling the target affinity towards antibody fragments simply by the presence or absence of calcium. From NMR spectroscopy we found that the molecular mechanism underlying the evolved switching behavior was a coupled calcium-binding and folding event where the target binding surface was intact and functional only in the presence of bound calcium. Notably, it was observed that the response to the employed selection pressures gave rise to the evolution of a cooperative folding mechanism. This observation illustrates why the cooperative folding reaction is an effective solution seen repeatedly in the natural evolution of fine-tuned macromolecular recognition. Engineering binding moieties to confer conditional target interaction has great potential due to the exquisite interaction control that is tunable to application requirements. Improved understanding of the molecular mechanisms behind regulated interactions is crucial to unlock how to engineer switchable proteins useful in a variety of biotechnological applications.

Evaluating the impact of human movement-induced airflow on particle dispersion: A novel real-time validation using IoT technology

Human movement significantly influences local airflow and particle dispersion in indoor environments. Therefore, this study integrates the dynamics of human walking into the analysis of airborne infection risks in a positive pressure isolation ward designed for the protection of immunocompromised patients. Real-time data collection was performed using an anemometer and IoT-based PM sensors to measure airflow velocities and particulate matter (PM) concentrations within a full-scale experimental chamber. Computational Fluid Dynamics (CFD) was used for the numerical simulations, and a User-Defined Function (UDF) code simulated the translational movement of a manikin. The results demonstrated strong agreement with the experimental data, thereby validating the airflow turbulence and Lagrangian-based Discrete Phase Model (DPM) in predicting the airflow velocities and particle transport. The study revealed that human walking substantially enhanced particle dispersion distance by 10-fold compared to static conditions, primarily attributed to intensified air mixing induced by the body movement. Furthermore, the CFD analysis underscored that the direction of walking plays a crucial role in airborne transmission. Specifically, walking away from a patient did not elevate infection risk, whereas approaching a patient significantly increased particle deposition in the patient-occupied region. This study highlights the critical need to consider both movement patterns and directional flow in managing airborne infection risks, contributing to the development of more effective infection control strategies in healthcare settings.

Transpulmonary Pressure-Guided Mechanical Ventilation in Severe Acute Respiratory Distress Syndrome in PICU: Single-Center Retrospective Study in North India, 2018–2021

Objectives: In this study, we have reviewed the association between esophageal pressure-guided positive end-expiratory pressure (PEEP) setting and oxygenation and lung mechanics with a conventional mechanical ventilation (MV) strategy in patient with moderate to severe pediatric acute respiratory distress syndrome (PARDS). Design: Retrospective cohort, 2018–2021. Setting: Tertiary PICU. Patients: Moderate to severe PARDS patients who required MV with PEEP of greater than or equal to 8 cm H2O. Interventions: Esophageal pressure (i.e., transpulmonary pressure [PTP]) guided MV vs. not. Measurements and Main Results: We identified 26 PARDS cases who were divided into those who had been managed with PTP-guided MV (PTP group) and those managed with conventional ventilation strategy (non-PTP). Oxygenation and lung mechanics were compared between groups at baseline (0 hr) and 24, 48, and 72 hours of MV. There were 13 patients in each group in the first 24 hours. At 48 and 72 hours, there were 11 in PTP group and 12 in non-PTP group. On comparing these groups, first, use of PTP monitoring was associated with higher median (interquartile range) mean airway pressure at 24 hours (18 hr [18–20 hr] vs. 15 hr [13–18 hr]; p = 0.01) and 48 hours (19 hr [17–19 hr] vs. 15 hr [13–17 hr]; p = 0.01). Second, use of PTP was associated with higher PEEP at 24, 48, and 72 hours (all p &lt; 0.05). Third, use of PTP was associated with lower Fio 2 and greater Pao 2 to Fio 2 ratio at 72 hours. Last, there were 18 of 26 survivors, and we failed to identify an association between use of PTP monitoring and survival. Conclusions: In this cohort of moderate to severe PARDS cases undergoing MV with PEEP greater than or equal to 8 cm H2O, we have identified some favorable associations of oxygenation status when PTP-guided MV was used vs. not. Larger studies are required.

Safety and efficacy of the Tao facemask for positive pressure ventilation in morbidly obese patients

Purpose: Positive-pressure mask ventilation is an essential skill for individuals providing basic and advanced airway interventions in a variety of clinical settings. The C-E grip technique is most commonly used with standard facemasks to provide an effective seal that allows for positive pressure ventilation. The Tao mask is a novel facemask that utilises an ergonomic grip by using downwards pressure of the palm of the hand accompanied by midline jaw lift. Specifically, the technique to create a seal involves downwards pressure of the palm centred on the mask accompanied by a jaw lift with four fingers centred under the mandible. A previous comparison between the Tao and standard masks revealed superior performance across a cross-section of average patients. The purpose of this study was to evaluate the safety and effectiveness of the Tao mask compared to the standard mask in a subset of patients with morbid obesity as defined by a body mass index (BMI) greater than or equal to 40 kg/m2. Methods: This prospective crossover trial included 156 patients aged ⩾18 years at the Medical University of South Carolina who were scheduled for elective surgery under general endotracheal anaesthesia with a BMI of ⩾40 kg/m2 at the time of surgery. After the induction of general anaesthesia, but prior to the administration of a neuromuscular blocking drug (NMBD), each patient was ventilated with both the standard and Tao masks, and effectiveness was measured using both the Han and Warters scales. The process was repeated after the administration of an NMBD. Results: Data were collected and analysed from 153 individuals. The mean BMI was 50.7 ± 9.3 kg/m2. The Tao mask ventilation scores were significantly lower (more effective) than the standard mask scores on both the Han and Warters Scales before pre-NMBD ( p = 0.0002 and p &lt; 0.001, respectively) and after post-NMBD ( p = 0.002 and p &lt; 0.001, respectively). On the Warters Scale, it was significantly easier to ventilate with the Tao Mask pre-NMBD ( p = 0.0001). On the Han Scale, the Tao mask was significantly easier than the standard mask post-NMBD ( p = 0.03). With regard to mask sequence, the mean Warters scores were lower for the Tao mask pre-NMBD only when the standard mask was used first ( p = 0.002). Similarly, the difference in the mean Warters scores post-NBMD was significant only when the standard mask was used first ( p = 0.02). Conclusion: The Tao mask demonstrated equivalent safety and superior effectiveness in ventilating morbidly obese surgical patients despite a trial design that favoured the standard mask owing to anaesthetist experience. The use of the Tao mask may be particularly beneficial in clinical situations involving inexperienced operators or in patients for whom mask ventilation is likely to be difficult. ClinicalTrials.gov registration number: NCT03473366

Tracheobronchoplasty for severe tracheobronchomalacia: a case-series of patients with acute and chronic critical comorbidities.

There is little data within the literature regarding tracheobronchoplasty (TBP) in the setting of the acute and chronically ill, morbidly obese, or ventilator dependent patients with Tracheobronchomalacia (TBM). Short- and long-term outcomes are studied. The series represents 12 TBM patients with American Society of Anesthesiologists (ASA) physical status scores of 3 to 5. Candidacy was based on bronchoscopic findings during spontaneous respirations with >90% collapse of the trachea and both mainstem bronchi. We used dynamic CT scan as an adjunct in those not mechanically ventilated. Our operative approach was a complete portal robotic approach for those outpatients (wheelchair dependent) and right thoracotomy for those who were already mechanically ventilated with 100% fraction of inspired oxygen (FiO2) with high pressure. Extracorporeal support was used in 2 patients. Patients who underwent robotic repair, were discharged without complications. Two patients who were critically ill and required extracorporeal support for their surgeries, were separated from extracorporeal membrane oxygenation (ECMO) on postoperative day 2. Three patients died at the follow-up. In 1 patient, the prolene mesh migrated into trachea and caused obstruction of the trachea and required removal with endobronchial techniques. The repair of TBM in patients with multiple comorbidities and with severe life-threatening problems in or outside the ICU, may have improvement due to the ability to wean from positive pressure ventilation. Surgical technique and the utilization of mesh support in TBP operations may need to be debated due to duration of the surgery in patients with severe comorbidities.

Lung-Protective Mechanical Ventilation in Patients with Severe Acute Brain Injury: A Multicenter Randomized Clinical Trial (PROLABI).

Rationale: Lung-protective strategies using low Vt and moderate positive end-expiratory pressure (PEEP) are considered best practice in critical care, but interventional trials have never been conducted in patients with acute brain injuries because of concerns about carbon dioxide control and the effect of PEEP on cerebral hemodynamics. Objectives: To test the hypothesis that ventilation with lower VT and higher PEEP compared to conventional ventilation would improve clinical outcomes in patients with acute brain injury. Methods: In this multicenter, open-label, controlled clinical trial, 190 adult patients with acute brain injury were assigned to receive either a lung-protective or a conventional ventilatory strategy. The primary outcome was a composite endpoint of death, ventilator dependency, and acute respiratory distress syndrome (ARDS) at Day 28. Neurological outcome was assessed at ICU discharge by the Oxford Handicap Scale and at 6 months by the Glasgow Outcome Scale. Measurements and Main Results: The two study arms had similar characteristics at baseline. In the lung-protective and conventional strategy groups, using an intention-to-treat approach, the composite outcome at 28 days was 61.5% and 45.3% (relative risk [RR], 1.35; 95% confidence interval [CI], 1.03-1.79; P = 0.025). Mortality was 28.9% and 15.1% (RR, 1.91; 95% CI, 1.06-3.42; P = 0.02), ventilator dependency was 42.3% and 27.9% (RR, 1.52; 95% CI, 1.01-2.28; P = 0.039), and incidence of ARDS was 30.8% and 22.1% (RR, 1.39; 95% CI, 0.85-2.27; P = 0.179), respectively. The trial was stopped after enrolling 190 subjects because of termination of funding. Conclusions: In patients with acute brain injury without ARDS, a lung-protective ventilatory strategy, as compared with a conventional strategy, did not reduce mortality, percentage of patients weaned from mechanical ventilation, or incidence of ARDS and was not beneficial in terms of neurological outcomes. Because of the early termination, these preliminary results require confirmation in larger trials. Clinical trial registered with www.clinicaltrials.gov (NCT01690819).

Raman spectroscopic insights into the pressure-induced phase transition in natural elbaite

Tourmaline [XY₃Z₆(T₆O₁₈)(BO₃)₃V₃W] is a potential carrier for water and boron cycles in the Earth's interior. Its high-pressure structural behavior has been extensively investigated by single-crystal or powder X-ray diffraction. Here, we collected Raman spectroscopy data of natural elbaite with two different compositions (Fe-poor elbaite and Fe-rich elbaite) up to 35.1 GPa to complementarily characterize the structural modifications proposed by previous studies. Our results reveal two clear discontinuous changes in high-pressure Raman spectra of both samples. The first change occurred at around 15 GPa, characterized by changes in Raman peak intensity, and the pressure dependence of the frequencies of several lattice vibration modes and hydroxyl stretching vibrations. The second change emerged at around 26 GPa and was marked by the systematic appearance of new Raman peaks. Based on previous X-ray diffraction studies, the change at around 26 GPa is likely caused by a phase transition from rhombohedral R3m to rhombohedral R3, whereas the change at around 15 GPa is likely caused by a change in compression mechanism. Furthermore, the WOH stretching vibrations at 3691 cm−1 in Fe-rich elbaite exhibited a negative pressure coefficient, contrasting with the positive pressure coefficient observed in Fe-poor elbaite, suggesting a significant influence of chemical composition on the evolution of stretching vibration in WOH groups under high pressure. After release of pressure, the spectra return to their initial state, indicating the reversibility of all observed changes.