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Abstract Acute gastrointestinal injury (AGI) is common in mechanically ventilated (MV) patients, but the potential association between ventilatory pressure parameters and AGI grade and their impact on mortality remains unclear. This study aimed to explore the association between ventilatory pressure parameters and AGI grade, and their interaction on all-cause mortality in MV patients. This study was a secondary analysis of a multicenter, prospective, observational study that enrolled adult patients with an expected duration of mechanical ventilation ≥ 48 h from 14 general intensive care units in Zhejiang Province between March and August 2014. The AGI grade was assessed daily on the basis of gastrointestinal symptoms, intra-abdominal pressures, and feeding intolerance in the first week of admission to the ICU. This study included 331 patients (69.2% men; mean age, 64.6 ± 18.9 years). Multivariate regression analysis showed that plateau pressure (Pplat) (OR 1.044, 95% CI 1.009–1.081, P = 0.013), serum creatinine (OR 1.003, 95% CI 1.001–1.006, P = 0.042) and APACHE II score (OR 1.035, 95% CI 1.021–1.072, P = 0.045) were independently associated with global AGI grade III/IV within 7 days of ICU admission. Moreover, global AGI grade (HR 2.228, 95% CI 1.561–3.182, P

With the advancement in the developmental project on the lower reaches of the Yarlung Tsangpo River, the influence of the plateau climate environment on the performance of a hydro-generator has received more and more attention from researchers. This study numerically simulated the thermal field of a hydro-generator with a 20 MW capacity under the effect of a plateau climate. Ambient pressure and temperature are two main factors that affect the temperature distribution of the generator. In addition, temperature distributions with different speeds are also studied under a plateau climate. The results show that the generator temperature decreases with increasing air pressure and speed. The generator temperature increases linearly with increasing ambient temperature. Among them, when the pressure lies in the range of 25–85 kPa, the temperature change gradient of the stator structure is very large. The temperature difference gradually decreases with the increase in air pressure. The temperature gradient gradually slows down when the air pressure is above 85 kPa. When the pressure is located at 55–85 kPa, the average temperature difference of the stator windings is 6.325 °C, and the average temperature difference of the stator core is 3.815 °C. Finally, the temperature distribution pattern can provide a basis for staff in different barometric pressure regions. It can also improve the safety and reliability of the hydro-generator under the effect of a plateau climate, which is important for improving its integrated hydraulic performance. [ABSTRACT FROM AUTHOR]

This article highlights the significance of measuring plateau pressure in spontaneously breathing patients as it provides valuable information about PMI (Pmusc Index), which serves as a surrogate for the patient's efforts during mechanical ventilation. The PMI value obtained from the difference between the end-inspiratory occlusion plateau pressure and the airway pressure before the occlusion (PEEP + PS) enables clinicians to estimate the patient's inspiratory effort accurately. The accurate measurement of patient efforts is crucial in optimizing pressure support during lung protective weaning strategies. By titrating pressure support based on PMI values, clinicians can provide personalized care to patients, reducing the risk of ventilator-induced lung injury and enhancing the likelihood of successful weaning.

Objective: To investigate the correlations between APACHE-II score and pressure parameters of mechanical ventilation in patients with acute respiratory distress syndrome (ARDS) and their value in prognostic evaluation. Methods: This was a retrospective study. The clinical data of 79 patients with ARDS treated in Shengzhou Hospital of Traditional Chinese Medicine from April 2020 to April 2022 were analyzed retrospectively. According to whether their APACHE-II scores were higher than 15, they were divided into low score group (n= 20) and high score group (n= 59). The plateau pressure (Pplat), driving pressure(ΔP) and mean airway pressure (Pmean) were compared. The correlation between APACHE-II score and pressure parameters of mechanical ventilation was analyzed. Based on the follow-up of 28-d survival, their Pplat, ΔP, Pmean and APACHE-II scores were compared. The value of APACHE-II score and pressure parameters in the prognostic evaluation of ARDS patients was analyzed. Results: Pplat, ΔP and Pmean in the low score group were significantly lower than those in the high score group(P<0.05). Pplat, ΔP, Pmean and APACHE-II score in the survival group were significantly lower than those in the control group(P<0.05). APACHE-II score showed significantly positive correlations with Pplat, ΔP and Pmean. The AUC of Pmean, Pplat, ΔP and APACHE-II score in predicting the prognosis and diagnosis of ARDS patients was 0.761, 0.833, 0.754 and 0.832, respectively. Conclusion: APACHE-II score of ARDS patients shows significantly positive correlations with pressure parameters of mechanical ventilation, and has diagnostic value for the prognosis of ARDS patients. [ABSTRACT FROM AUTHOR]

Thirty years ago, the traditional approach to mechanical ventilation consisted of the normalization of PaCO2 and pH at the expense of using a tidal volume (VT) of 10–15 mL kg-1. But then, the use of 6–8 mL kg-1 became a dogma for ventilating patients either with acute respiratory distress syndrome (ARDS) or without lung disease in the operating theatre. It is currently recognized that even low tidal volumes may be excessive for some patients and insufficient for others, depending on its distribution in the aerated lung parenchyma. To carry out intraoperative protective mechanical ventilation, medical literature has focused on positive end expiratory pressure (PEEP), plateau pressure (Paw plateau), and airway driving pressure (ΔPaw). However, considering its limitations, other parameters have emerged that represent a better reflection of isolated lung stress, such as transpulmonary pressure (PL) and transpulmonary driving pressure (ΔPL). These parameters are less generalized in clinical practice due to the requirement of an oeso­phageal balloon for their measurement and therefore their cumbersome application in the operating theatre. However, its study helps in the interpretation of the rest of the ventilator pressures to optimize intraoperative mechanical ventilation. This article defines and develops protective ventilation parameters, breaks down their determinants, mentions their limitations, and offers recommendations for their use intraoperatively.

With the advancement in the developmental project on the lower reaches of the Yarlung Tsangpo River, the influence of the plateau climate environment on the performance of a hydro-generator has received more and more attention from researchers. This study numerically simulated the thermal field of a hydro-generator with a 20 MW capacity under the effect of a plateau climate. Ambient pressure and temperature are two main factors that affect the temperature distribution of the generator. In addition, temperature distributions with different speeds are also studied under a plateau climate. The results show that the generator temperature decreases with increasing air pressure and speed. The generator temperature increases linearly with increasing ambient temperature. Among them, when the pressure lies in the range of 25–85 kPa, the temperature change gradient of the stator structure is very large. The temperature difference gradually decreases with the increase in air pressure. The temperature gradient gradually slows down when the air pressure is above 85 kPa. When the pressure is located at 55–85 kPa, the average temperature difference of the stator windings is 6.325 °C, and the average temperature difference of the stator core is 3.815 °C. Finally, the temperature distribution pattern can provide a basis for staff in different barometric pressure regions. It can also improve the safety and reliability of the hydro-generator under the effect of a plateau climate, which is important for improving its integrated hydraulic performance.

Background Mortality in ARDS was reduced significantly after the introduction of the low tidal volume ventilation strategy. It has been recently shown that lung-protective ventilation strategies should primarily target driving pressure rather than Vt and that ventilator induced lung injury is not just dependent on tidal volume but also other factors like respiratory rate and driving pressure. Ventilator induced lung injury is also thought to be dependent on the amount of energy transferred by the ventilator to the patient which in turn is dependent on tidal volume size (VT), plateau pressure (Pplat), respiratory rate (RR). Mechanical power can be calculated accurately through power equations which can increase their applicability in clinical practice. One simple composite equation (driving pressure multiplied by four plus respiratory rate [4DPRR]) has been recently suggested as a simple surrogate for the power equation. This equation also doesn’t include PEEP as it has been theorized that it is the only elastic dynamic component of driving energy which affects the outcome and not the elastic static component (i.e., PEEP) and the resistive power (related to flow and airway resistance). Objectives To assess the mechanical power as measured by 4DPRR in mechanically ventilated patients who have moderate to severe COVID-19 ARDS. Methods: We obtained data on ventilatory variables and mechanical power from the patients who were admitted with moderate to severe COVID ARDS in our hospital from March 2021 to June 2021. Results We included 34 patients (28% women; mean age, 57 ± 17 yrs.). The average ΔP was 21.44 ± 3.98 cmH2O, the RR was 23.8 ± 3.84 breaths/min, and the mean driving pressure was 21.4 cmH2O. 28% (n = 10) of patients expired. There was no significant association of 4DPRR (P 0.72), Pplat (P 0.79).and RR (P 0.21) with mortality as predicted by area under ROC curves. Conclusions Driving power and plateau pressure were associated with mortality during controlled mechanical ventilation in COVID ARDS, but a simpler model of mechanical power using only the driving pressure and respiratory rate was found to be a poor predictor of mortality.

Background: Wound dehiscence is a serious surgical complication associated with exploratory laparotomy, often leading to significant morbidity and mortality. Identifying predictive parameters for wound dehiscence is essential for improving patient outcomes. This retrospective study aimed to evaluate the utility of plateau pressure, a parameter typically used in mechanical ventilation, as a predictive tool for wound dehiscence in patients undergoing exploratory laparotomy. Methods: Data were collected from 100 patients admitted to tertiary care Centre, Karad, between December 2020 and May 2022. Demographic characteristics, etiological aspects, preoperative albumin levels, and diabetes mellitus status were recorded. Plateau pressure values were obtained from mechanical ventilation records. The primary outcome was the occurrence of wound dehiscence. Statistical analysis included descriptive statistics, chi-squared tests, t-tests, Mann-Whitney U tests, and multivariate logistic regression. Results: Among the 100 patients, 12 (12%) developed wound dehiscence. Patients with plateau pressures greater than 25 cmH2O exhibited the highest incidence of wound dehiscence (53.6%). A significant association was found between higher plateau pressure values and an increased risk of wound dehiscence (p < 0.05). Multivariate logistic regression confirmed this association, adjusting for potential confounding factors. Conclusion: This study suggests that elevated plateau pressure may serve as a valuable predictive parameter for wound dehiscence in exploratory laparotomy patients. The findings highlight the potential clinical significance of incorporating plateau pressure into preoperative risk assessment and preventive strategies, ultimately contributing to improved patient care and outcomes. Further research is warranted to validate and expand upon these findings. [ABSTRACT FROM AUTHOR]

The structure and hydrogenation properties of (V0.85Fe0.15)100−xMx–Ce (x = 0, 1, 3, 5; at%) alloys with M = Cr, Mo, Al were investigated. All the alloys show the same phase composition consisting of BCC matric and CeO2 phases which distribute along the grain boundary. The hydrogen capacities of (V0.85Fe0.15)100−xMx–Ce change little with M, and none of them exceeds 2.0 wt%. But the plateau pressure shows remarkable linearly variation with the amount of M and the lattice parameter of BCC matric. The additions of Cr, Mo and Al raise the plateau, but the linear relation of plateau versus BCC lattice parameter of Mo/Al-added alloys is opposite to that of Cr-added alloys and many other conventional hydrogen storage alloys. The radius of hydrogen site is introduced to explain the inconsistent. The plateau pressure of (V0.85Fe0.15)100−xMx–Ce with any kind of M added increases with the contraction of the hydrogen site. The plateau pressure of (V0.85Fe0.15)100−xMx–Ce can also be reflected by the stability of hydride which is judged by the enthalpy change during the dehydrogenation. [ABSTRACT FROM AUTHOR]

Purpose: In children with acute respiratory distress syndrome receiving mechanical ventilation, the peak inspiratory pressure (PIP) is close to plateau pressure (P PLAT ) when inspiratory flow approaches zero. We aimed to evaluate the reliability of PIP to estimate P PLAT in infants with severe respiratory viral infection (SRVI), characterized by increased airway resistance, and the accuracy of an equational model to estimates P PLAT (eP PLAT ) based on PIP., Methods: This was a retrospective observational study including mechanically ventilated children (1 to 24 month old) with SRVI, whose respiratory mechanics measurements were performed to evaluate PIP and P PLAT. The measured P PLAT was compared with the result of the equation: eP PLAT  = PIP - [5.067 - (0.858 × static compliance) - (0.018 × inspiratory resistance) - (0.390 × pressure above positive-end expiratory pressure) + (4.989 × inspiratory time)]., Results: Thirty-seven patients were included, with a median age of 3 (2-5) months. They presented a high inspiratory and expiratory resistance (136 ± 43 and 168 ± 66 cmH 2 O/L/s, respectively) and a moderate reduction in static compliance: 0.75 ± 0.3 mL/kg/cmH 2 O. PIP overestimated P PLAT (33 ± 3 and 26 ± 5 cmH 2 O, p = 0.01), with a mean difference of 7.3 ± 4 cmH 2 O. Moreover, the Bland-Altman analysis demonstrated a mean difference between P PLAT and eP PLAT of 1.0 ± 4.0 cmH 2 O, with 95% limits of agreement of -6.9 and 8.8., Conclusions: A significant difference between PIP and P PLAT was observed in infants with SRVI. The equation model was inaccurate for estimating P PLAT based on PIP. Any estimation of P PLAT from PIP needs to consider the resistance component of the respiratory system., (© 2024 Wiley Periodicals LLC.)

BACKGROUND: Mechanical power applied to the respiratory system (MP RS ) is associated with ventilator-induced lung injury (VILI) and ARDS mortality. Absent automated ventilator MP RS measurements, the alternative is clinically unwieldy equations. However, simplified surrogate formulas are now available and accurately reflect values produced by airway pressure-volume curves. This retrospective, observational study examined whether the surrogate pressure-control equation alone could accurately assess mortality risk in ARDS subjects managed almost exclusively with volume-control ventilation. METHODS: 948 subjects were studied in whom invasive mechanical ventilation and implementation of ARDSNet ventilator protocols commenced ≤ 24hr after ARDS onset, and who survived > 24hr. MP RS was calculated as 0.098 x respiratory frequency x VT x (PEEP + driving pressure [P DR ]). MP RS was assessed as a risk factor for hospital mortality, and compared between non-survivors and survivors across Berlin Definition classifications. In addition, mortality was compared across 4 MP RS thresholds associated with VILI or mortality (ie. 15, 20, 25 and 30 J/m). RESULTS: MP RS was associated with increased mortality risk: Odds Ratio (95% CI) of 1.06 (1.04-1.07) per J/m, P<0.001). Median MP RS differentiated non-survivors from survivors in Mild (24.7 vs. 18.5 J/m, respectively, P==0.034); Moderate (25.7 vs. 21.3 J/m, P<0.001); and Severe ARDS (28.7 vs. 23.5 J/m, P<0.001). Across 4 MP RS thresholds mortality increased from 23-29% when MP RS was < threshold vs. 38-51% when MP RS was > threshold (P<0.001). In the > cohort the Odds Ratio (95%CI) increased from 2.03 (1.34-3.12) to 2.51 (1.87-3.33). CONCLUSION: The pressure control surrogate formula is sufficiently accurate to assess mortality in ARDS, even when using volume control ventilation. In our subjects when MP RS exceeds established cut-off values for VILI or mortality risk, we found mortality risk consistently increased by a factor of > 2.0., (Copyright © 2024 by Daedalus Enterprises.)

Abstract Background Controversies exist on the nature of COVID-19 related acute respiratory distress syndrome (ARDS) in particular on the static compliance of the respiratory system (Crs). We aimed to analyze the association of Crs with outcome in COVID-19-associated ARDS, to ascertain its determinants and to describe its evolution at day-14. Methods In this observational multicenter cohort of patients with moderate to severe Covid-19 ARDS, Crs was measured at day-1 and day-14. Association between Crs or Crs/ideal body weight (IBW) and breathing without assistance at day-28 was analyzed with multivariable logistic regression. Determinants were ascertained by multivariable linear regression. Day-14 Crs was compared to day-1 Crs with paired t-test in patients still under controlled mechanical ventilation. Results The mean Crs in 372 patients was 37.6 ± 13 mL/cmH2O, similar to as in ARDS of other causes. Multivariate linear regression identified chronic hypertension, low PaO2/FiO2 ratio, low PEEP, and low tidal volume as associated with lower Crs/IBW. After adjustment on confounders, nor Crs [OR 1.0 (CI 95% 0.98–1.02)] neither Crs/IBW [OR 0.63 (CI 95% 0.13–3.1)] were associated with the chance of breathing without assistance at day-28 whereas plateau pressure was [OR 0.93 (CI 95% 0.88–0.99)]. In a subset of 108 patients, day-14 Crs decreased compared to day-1 Crs (31.2 ± 14.4 mL/cmH2O vs 37.8 ± 11.4 mL/cmH2O, p

Rationale: Monitoring tidal cycle mechanics is key to lung protection. For this purpose, compliance and driving pressure of the respiratory system are often measured clinically using the plateau pressure, obtained after imposing an extended end-inspiratory pause, which allows for relaxation of the respiratory system and redistribution of inflation volume (method A). Alternative methods for estimating compliance and driving pressure utilize the measured pressure at the earliest instance of zero flow (method B), the inspiratory slope of the pressure-time tracing during inflation with constant flow (method C), and the expiratory time constant (method D). Methods: Ten passive mechanically ventilated subjects, at a large tertiary referral center, underwent measurements of compliance and driving pressure using the four different methods. The inspiratory tidal volume, inspiratory to expiratory ratio, and positive end expiratory pressures were then adjusted from baseline and the measurements re-obtained. Results: Method A yielded consistently higher compliance and lower driving pressure calculations compared to methods B and C. Methods B and C most closely approximated one another. Method D did not yield a consistent reliable pattern. Conclusion: Static measurements of compliance and driving pressure using the plateau pressure may underestimate the maximum pressure experienced by the most vulnerable lung units during dynamic inflation. Utilizing the pressure at zero flow as a static measurement, or the inspiratory slope as a dynamic measurement, may calculate a truer estimate of the maximum alveolar pressure that generates stress upon compromised lung units. [ABSTRACT FROM AUTHOR]

Introduction: Among many other techniques for Abdominal Wall Reconstruction (AWR), posterior component separation with Transversus Abdominis Release (TAR), continues to gain popularity and it is increasingly used with promising long-term results. Our goal was to evaluate the influence of TAR with mesh retromuscular reinforcement on the intra-abdominal pressure (IAP) and respiratory function in a series of patients with complex incisional hernias (IH).Methods: Since November 2014 through February 2019, patients with TAR were identified in the Clinical Department of Surgery database and were retrospectively reviewed. Outcome measures include: demographics, pre- and perioperative details, preoperative and postoperative IAP and plateau pressure (PP).Results: One-hundred-and-one consecutive TAR procedures (19.7% from all incisional hernia repairs) were analyzed. Mean age was 63 years with a mean Body Mass Index (BMI) of 31.85 kg/m2 (25-51). Diabetes and Chronic Obstructive Pulmonary Disease (COPD) were the main major comorbidities. Mean hernia defect area was 247 cm2 (104-528 cm2).Conclusion: TAR is a safe and sound procedure with acceptable modifications of the IAP morbidity and recurrence rate when correctly performed on the right patient. [ABSTRACT FROM AUTHOR]

RationaleMonitoring tidal cycle mechanics is key to lung protection. For this purpose, compliance and driving pressure of the respiratory system are often measured clinically using the plateau pressure, obtained after imposing an extended end-inspiratory pause, which allows for relaxation of the respiratory system and redistribution of inflation volume (method A). Alternative methods for estimating compliance and driving pressure utilize the measured pressure at the earliest instance of zero flow (method B), the inspiratory slope of the pressure-time tracing during inflation with constant flow (method C), and the expiratory time constant (method D).MethodsTen passive mechanically ventilated subjects, at a large tertiary referral center, underwent measurements of compliance and driving pressure using the four different methods. The inspiratory tidal volume, inspiratory to expiratory ratio, and positive end expiratory pressures were then adjusted from baseline and the measurements re-obtained.ResultsMethod A yielded consistently higher compliance and lower driving pressure calculations compared to methods B and C. Methods B and C most closely approximated one another. Method D did not yield a consistent reliable pattern.ConclusionStatic measurements of compliance and driving pressure using the plateau pressure may underestimate the maximum pressure experienced by the most vulnerable lung units during dynamic inflation. Utilizing the pressure at zero flow as a static measurement, or the inspiratory slope as a dynamic measurement, may calculate a truer estimate of the maximum alveolar pressure that generates stress upon compromised lung units.

This review compares the safety and effectiveness of volume control ventilation (VCV) and pressure control ventilation (PCV) during laparoscopic surgery. Nine studies were chosen for in-depth examination following the application of stringent inclusion and exclusion criteria to the 184 publications that the literature search turned up. PCV is well-known for its capacity to preserve lower peak airway pressures during laparoscopic procedures, lowering the risk of volutrauma and barotrauma and enhancing oxygenation under these conditions of elevated intra-abdominal pressures. On the other hand, VCV guarantees a constant tidal volume and offers accurate ventilation management, both of which are essential for preserving stable carbon dioxide levels. VCV, however, may result in higher peak airway pressures, raising the risk of lung damage brought on by a ventilator. Research indicates that PCV provides better respiratory mechanics management during laparoscopic surgery, but VCV consistent tidal volume delivery is useful in some clinical situations. When choosing between PCV and VCV, the anesthesia team's experience, the demands of each patient, and the surgical circumstances should all be taken into consideration. Real-time monitoring tools and sophisticated ventilatory technology are essential for maximizing ventilation techniques. Further improving patient outcomes can be achieved by incorporating multimodal anesthesia approaches, such as the use of muscle relaxants and customized intraoperative fluid management. Muscle relaxants optimize conditions for mechanical ventilation by ensuring adequate muscle relaxation, reducing the risk of ventilator-associated lung injury, and enabling more precise control of ventilation parameters. Tailored intraoperative fluid management helps maintain optimal lung mechanics by avoiding fluid overload, which can lead to pulmonary edema and compromised gas exchange, necessitating adjustments in ventilation strategy. While both ventilation modalities can be utilized efficiently, the research suggests that PCV may be more advantageous in controlling oxygenation and airway pressures. In the dynamic and demanding world of laparoscopic surgery, ongoing research and clinical innovation are crucial to improving these tactics and guaranteeing the best possible treatment. In order to obtain the best possible patient outcomes during laparoscopic surgeries, this review emphasizes the significance of customized breathing techniques., Competing Interests: Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work., (Copyright © 2024, Sawant et al.)

• The TiFe 0.8 Al 0.2 alloy had plateau pressure with a large slope. • The alloy absorbed hydrogen at room temperature without any thermal activation process. • The Ti-rich Ti 2 Fe phase was precipitated in the alloy. • The matrix of the alloy was separated into two B2 phase with different composition. In the TiFe 0.8 Al 0.2 alloy, the Ti 2 Fe phase was precipitated, and the B2 phase was separated into two B2 phases. The alloy absorbed hydrogen at room temperature without any thermal activation process by forming the Ti 2 Fe phase. The hydrogen absorption and desorption behaviors were examined, and the slope of the plateau pressure was severely formed. The two B2 phases had different compositions. The hydride-forming enthalpies of the two B2 phases were calculated through a density function theory calculation, and the values of the two B2 phases were different. Therefore, it was confirmed that the slope of the plateau pressure was severely formed because of the separation of the B2 phase. [ABSTRACT FROM AUTHOR]

Objectives: Inspiratory holds with measures of airway pressure to estimate driving pressure (elastic work) are often limited to patients without respiratory effort. We sought to evaluate if measures of airway pressure during inspiratory holds could be used for patients with spontaneous respiratory effort during mechanical ventilation to estimate the degree of spontaneous effort and elastic work.Design: We compared the direction and degree of change in airway pressure during inspiratory holds versus esophageal pressure through secondary analysis of physiologic data.Setting: ICUs at Children's Hospital Los Angeles.Patients: Children with pediatric acute respiratory distress syndrome with evidence of spontaneous respiration while on pressure control or pressure support ventilation.Interventions: Inspiratory hold maneuvers.Measurements and Main Results: From airway pressure, we defined "plateau - peak pressure" as Pmusc, index, which was divided into three categories for analysis (< -1 ["negative"], between -1 and 1 ["neutral"], and > 1 cm H2O ["positive"]). A total of 30 children (age 36.8 mo [16.1-70.3 mo]) from 65 study days, comprising 118 inspiratory holds were included. Pmusc, index was "negative" in 29 cases, was "neutral" in 17 cases, and was "positive" in 72 cases. As Pmusc, index went from negative to neutral to positive, there was larger negative deflection in esophageal pressure -5.0 (-8.2 to 1.9), -5.9 (-7.6 to 4.3), and -10.7 (-18.1 to 7.9) cm H2O (p < 0.0001), respectively. There was a correlation between max negative esophageal pressure and Pmusc, index (r = -0.52), and when Pmusc, index was greater than or equal to 7 cm H2O, the max negative esophageal pressure was greater than 10 cm H2O. There was a stronger correlation between Pmusc, index and markers of elastic work from esophageal pressure (r = 0.84).Conclusions: The magnitude of plateau minus peak pressure during an inspiratory hold is correlated with the degree of inspiratory effort, particularly for those with high elastic work. It may be useful to identify patients with excessively high effort or high driving pressure. [ABSTRACT FROM AUTHOR]

Recruitment maneuvers in ARDS are used to improve oxygenation and lung mechanics by applying high airway pressures to reopen collapsed or obstructed peripheral airways and alveoli. In the early 1990s, recruitment maneuvers became a central feature of a variant form of lungprotective ventilation known as open-lung ventilation. This strategy is based on the belief that repetitive opening and closing of distal airspaces induces shear injury and therefore contributes both to ventilator-induced lung injury and ARDS-associated mortality. However, the largest multi-center randomized controlled trial of open-lung ventilation in moderate to severe ARDS reported that recruitment maneuver plateau pressures of 50-60 cm H2O were associated with significantly higher mortality compared to traditional lung-protective ventilation. Despite being based on well conducted preclinical and clinical recruitment maneuver studies, the higher mortality associated with the open-lung ventilation strategy requires re-examining the assumptions and conclusions drawn from those previous studies. This narrative review examines the evidence used to design recruitment maneuver strategies. We also review the radiologic, rheologic, and histopathologic evidence regarding the nature of lung injury and the phenomena of recruitment and de-recruitment as it informs our perceptions of recruitment potential in ARDS. Major lungprotective ventilation clinical trial data and other clinical data are also examined to assess the practical necessity of recruitment maneuvers in ARDS and whether a subset of cases might benefit from pursuing recruitment maneuver therapy. Finally, a less a radical approach to recruitment maneuvers is offered that might achieve the goals of recruitment maneuvers with less risk of harm. [ABSTRACT FROM AUTHOR]

Background: Controversies exist on the nature of COVID-19 related acute respiratory distress syndrome (ARDS) in particular on the static compliance of the respiratory system (Crs). We aimed to analyze the association of Crs with outcome in COVID-19-associated ARDS, to ascertain its determinants and to describe its evolution at day-14.Methods: In this observational multicenter cohort of patients with moderate to severe Covid-19 ARDS, Crs was measured at day-1 and day-14. Association between Crs or Crs/ideal body weight (IBW) and breathing without assistance at day-28 was analyzed with multivariable logistic regression. Determinants were ascertained by multivariable linear regression. Day-14 Crs was compared to day-1 Crs with paired t-test in patients still under controlled mechanical ventilation.Results: The mean Crs in 372 patients was 37.6 ± 13 mL/cmH2O, similar to as in ARDS of other causes. Multivariate linear regression identified chronic hypertension, low PaO2/FiO2 ratio, low PEEP, and low tidal volume as associated with lower Crs/IBW. After adjustment on confounders, nor Crs [OR 1.0 (CI 95% 0.98-1.02)] neither Crs/IBW [OR 0.63 (CI 95% 0.13-3.1)] were associated with the chance of breathing without assistance at day-28 whereas plateau pressure was [OR 0.93 (CI 95% 0.88-0.99)]. In a subset of 108 patients, day-14 Crs decreased compared to day-1 Crs (31.2 ± 14.4 mL/cmH2O vs 37.8 ± 11.4 mL/cmH2O, p < 0.001). The decrease in Crs was not associated with day-28 outcome.Conclusion: In a large multicenter cohort of moderate to severe COVID-19 ARDS, mean Crs was decreased below 40 mL/cmH2O and was not associated with day-28 outcome. Crs decreased between day-1 and day-14 but the decrease was not associated with day-28 outcome. [ABSTRACT FROM AUTHOR]

Introduction: Accumulation of secretions in an endotracheal tube can increase the resistance to flow resulting in an increased patient work of breathing when the patient is interacting with the ventilator. Retained secretions can also serve as an infection risk. Standard suction catheters are limited in their ability to keep the lumen of the endotracheal tube clear. A novel closed-suction catheter has been introduced that incorporates a balloon at its distal end that, when inflated, physically scrapes secretions out of the endotracheal tube (CleanSweep catheter (CSC), Teleflex, Morrisville NC). We hypothesized that the CSC would be more efficient at removing secretions from inside the endotracheal tube than a standard suction catheter (SSC). Methods: We performed a bench study examining resistive pressures across different sizes of endotracheal tubes when cleaned by the CSC as compared with an SSC. This study was followed by a prospective crossover study again comparing the CSC with an SSC in intubated intensive care unit patients receiving mechanical ventilation and requiring frequent suctioning. Results: For the bench study the CSC was significantly better in reducing airway resistive pressures (P < 0.001). In the prospective crossover study the CSC over 2 h also removed significantly more secretions than the SSC (P < 0.05). Conclusion: Both our bench and crossover clinical study demonstrated improved clearance of secretions with the CSC vs an SSC. Further research is needed to ascertain the clinical outcome benefits of enhanced secretion removal. [ABSTRACT FROM AUTHOR]

Invasive mechanical ventilation allows clinicians to support gas exchange and work of breathing in patients with respiratory failure. However, there is also potential for iatrogenesis. By understanding the benefits and limitations of different modes of ventilation and goals for gas exchange, clinicians can choose a strategy that provides appropriate support while minimizing harm. The ventilator can also provide crucial diagnostic information in the form of respiratory mechanics. These, and the mechanical ventilation strategy, should be regularly reassessed., Competing Interests: Disclosures J.C. Szafran has nothing to disclose. B.K. Patel receives funding from the NIH, United States/NHLBI (K23 HL148387) and the SECURED grant., (Copyright © 2024 Elsevier Inc. All rights reserved.)

The article compares the two methods, and discusses their differences in terms of resistive pressure drop. Topics include the use of Dynamic, and Static methods to estimate the transpulmonary pressure; that higher resistive pressure drops lead to more negative alveolar pressures; and that absolute thresholds of driving pressures cannot be directly translated from static to dynamic conditions.

Background: In view of the high mortality rate of immunocompromised patients with ARDS, it is important to identify targets for improvement.Research Question: This study investigated factors associated with mortality in this specific ARDS population, including factors related to respiratory mechanics (plateau pressure [Pplat,rs], compliance [Crs], and driving pressure [ΔPrs]).Study Design and Methods: This study consisted of a predefined secondary analysis of the EFRAIM data. Overall, 789 of 1,611 patients met the Berlin criteria for ARDS, and Pplat,rs, ΔPrs, and Crs were available for 494 patients. A hierarchical model was used to assess factors at ARDS onset independently associated with hospital mortality.Results: Hospital mortality was 56.3%. After adjustment, variables independently associated with hospital mortality included ARDS of undetermined etiology (OR, 1.66; 95% CI, 1.01-2.72), need for vasopressors (OR, 1.91; 95% CI, 1.27-2.88), and need for renal replacement therapy (OR, 2.02; 95% CI, 1.37-2.97). ARDS severity according to the Berlin definition, neutropenia on admission, and the type of underlying disease were not significantly associated with mortality. Before adjustment, higher Pplat,rs, higher ΔPrs, and lower Crs were associated with higher mortality. Addition of each of these individual variables to the final hierarchical model revealed a significant association with mortality: ΔPrs (OR, 1.08; 95% CI, 1.05-1.12), Pplat,rs (OR, 1.07; 95% CI, 1.04-1.11), and Crs (OR, 0.97; 95% CI, 0.95-0.98). Tidal volume was not associated with mortality.Interpretation: In immunocompromised patients with ARDS, respiratory mechanics provide additional prognostic information to predictors of hospital mortality. Studies designed to define lung-protective ventilation guided by these physiological variables may be warranted in this specific population. [ABSTRACT FROM AUTHOR]

Background: Pressures measured during mechanical ventilation provide important information about the respiratory system mechanics and can help predict outcomes. Methods: The electronic medical records of patients hospitalized between 2010 and 2016 with sepsis who required mechanical ventilation were reviewed to collect demographic information, clinical information, management requirements, and outcomes, such as mortality, ICU length of stay, and hospital length of stay. Mechanical ventilation pressures were recorded on the second full day of hospitalization. Results: This study included 312 adult patients. The mean age is 59.1 ± 16.3 years; 57.4% were men. The mean BMI was 29.3 ± 10.7. Some patients had pulmonary infections (46.2%), and some patients had extrapulmonary infections (34.9%). The overall mortality was 42.6%. In a multi-variable model that included age, gender, number of comorbidities, APACHE 2 score, and PaO2/FiO2 ratio, peak pressure, plateau pressure, driving pressure, and PEEP all predicted mortality when entered into the model separately. There was an increase in peak pressure, plateau pressure, and driving pressure across BMI categories ranging from underweight to obese. Conclusions: This study demonstrates that ventilator pressure measurements made early during the management of patients with acute respiratory failure requiring mechanical ventilation provide prognostic information regarding outcomes, including mortality. Patients with high mechanical ventilator pressures during the early course of their acute respiratory failure require more attention to identify reversible disease processes when possible. In addition, increased BMIs are associated with increased ventilator pressures, and this increases the complexity of the clinical evaluation in the management of obese patients. [ABSTRACT FROM AUTHOR]

Zr x V 5 Fe(x = 3, 5, 7, 8, 9) alloys were designed to investigate the influence of Zr addition on hydrogenation performance. The alloys were prepared by arc melting and then annealed at 1273K for 168 h. The results showed that the alloys were composed of α-Zr and C15–ZrV 2 phases. The cell volume of C15–ZrV 2 phase firstly increased and then decreased as the content of Zr increased, while the reversed trend was found for the cell volume of α-Zr phase, which was related to the stoichiometric ratio of elements. α-Zr phase distributed in C15–ZrV 2 phase matrix in Zr x V 5 Fe(x = 5, 7, 8, 9) alloys, among which Zr 7 V 5 Fe alloy showed the best distribution. The PCT curves of the alloys under 623 K, 673 K and 723 K showed that the hydrogen absorption plateau pressure of the phases in different alloys decreased gradually with the increasing content of Zr. However C15–ZrV 2 phase in Zr 7 V 5 Fe alloy had the lowest hydrogen absorption plateau pressure at room temperature, which was consistent with the change tendency of the corresponding cell volume. Moreover, the kinetic curves of hydrogen absorption at 623 K revealed that Zr 7 V 5 Fe alloy with the smallest average particle size and the largest phase boundary area showed the fastest hydrogen absorption kinetics. Compared with other four alloys(including St707 alloy), Zr 7 V 5 Fe alloy is more suitable for the use of getter. Image 1 • Zr 7 V 5 Fe alloy has the lowest plateau pressure among Zr x V 5 Fe(x = 3-9) alloys at 300K. • Zr 7 V 5 Fe alloy has the fastest hydriding kinetics among Zr x V 5 Fe(x = 3-9) alloys. • Zr 7 V 5 Fe alloy is the most easily pulverized among Zr x V 5 Fe(x = 3-9) alloys. • Zr 7 V 5 Fe alloy shows the best phase distribution among Zr x V 5 Fe(x = 3-9) alloys. [ABSTRACT FROM AUTHOR]

Abstract Background Lung protective mechanical ventilation (MV) is the corner stone of therapy for ARDS. However, its use may be limited by respiratory acidosis. This study explored feasibility of, effectiveness and safety of low flow extracorporeal CO2 removal (ECCO2R). Methods This was a prospective pilot study, using the Abylcap® (Bellco) ECCO2R, with crossover off-on-off design (2-h blocks) under stable MV settings, and follow up till end of ECCO2R. Primary endpoint for effectiveness was a 20% reduction of PaCO2 after the first 2-h. Adverse events (AE) were recorded prospectively. We included 10 ARDS patients on MV, with PaO2/FiO2

The risk of ventilator induced lung injury in mechanically ventilated (MV) critically ill patients can be mitigated by patient-specific optimisation of ventilator settings. Recent studies have shown that driving pressure, i.e. the difference between plateau pressure (Pplat) and PEEP, is a strong indicator for survival in MV patients suffering from ARDS. However, to measure Pplat, an extended end-inspiratory pause (EIP) has to be applied, possibly interrupting ventilation therapy. This study presents a method for predicting Pplat from normal breaths in MV patients.

Graphical abstract Highlights • The first hydrogen absorption plateau of V-based alloys were studied. • Alloying V with 3 at.% Ru obtained highest hydrogen pressure and initial diffusion. • Hydrogen diffusion behaviors of V-3A powders were predicted by DFT. • Surface morphology of V-3A powders decided the initial hydrogen absorption rate. Abstract The hydrogen absorption properties and diffusion behavior in V-3A alloys (V, V 97 Al 3 , V 97 Ru 3) were studied by pressure-composition-temperature measurements and first-principles calculations. It was found that addition of Al and Ru could increase first plateau pressure. With the largest surface area among these alloy powders, V-3Ru achieved the highest hydrogen diffusivity at 433 K under an initial pressure of 1500 Pa. Hydrogen diffusion behaviors were examined by DFT calculations of barriers in both surface and internal cases of V-3A alloys. It revealed that initial diffusion rate was related to surface morphology. The results are expected to provide useful guidelines for understanding hydrogen absorption and diffusion properties of hydrogen storage materials. [ABSTRACT FROM AUTHOR]