Cellular senescence contributes to mechanical ventilation-induced diaphragm dysfunction by upregulating p53 signalling pathways.

BACKGROUND: Mechanical ventilation can cause acute atrophy and injury in the diaphragm, which are related to adverse clinical results. However, the underlying mechanisms of ventilation-induced diaphragm dysfunction (VIDD) have not been well elucidated. The current study aimed to explore the role of cellular senescence in VIDD. METHODS: A total of twelve New Zealand rabbits were randomly divided into 2 groups: (1) spontaneously breathing anaesthetized animals (the CON group) and (2) mechanically ventilated animals (for 48 h) in V-ACV mode (the MV group). Respiratory parameters were collected during ventilation. Diaphragm were collected for further analyses. RESULTS: Compared to those in the CON group, the percentage and density of sarcomere disruption in the MV group were much higher (p < 0.001, both). The mRNA expression of MAFbx and MuRF1 was upregulated in the MV group (p = 0.003 and p = 0.006, respectively). Compared to that in the CON group, the expression of MAFbx and MuRF1 detected by western blotting was also upregulated (p = 0.02 and p = 0.03, respectively). Moreover, RNA-seq showed that genes associated with senescence were remarkably enriched in the MV group. The mRNA expression of related genes was further verified by q-PCR (Pai1: p = 0.009; MMP9: p = 0.008). Transverse cross-sections of diaphragm myofibrils in the MV group showed more intensive positive staining of SA-ßGal than those in the CON group. p53-p21 axis signalling was elevated in the MV group. The mRNA expression of p53 and p21 was significantly upregulated (p = 0.02 and p = 0.05, respectively). The western blot results also showed upregulation of p53 and p21 protein expression (p = 0.03 and p = 0.05, respectively). Moreover, the p21-positive staining in immunofluorescence and immunohistochemistry in the MV group was much more intense than that in the CON group (p < 0.001, both). CONCLUSIONS: In a rabbit model, we demonstrated that mechanical ventilation in A/C mode for 48 h can still significantly induce ultrastructural damage and atrophy of the diaphragm. Moreover, p53-dependent senescence might play a role in mechanical ventilation-induced dysfunction. These findings might provide novel therapeutic targets for VIDD.

Global biomarkers trends in acute kidney injury: a bibliometric analysis.

OBJECTIVES: Acute kidney injury (AKI) is a common global condition with high morbidity and mortality rates. Biomarkers can aid in the diagnosis, prediction, intervention, and outcome assessment of AKI. This study aimed to summarize the current research status and identify research hotspots for AKI biomarkers using bibliometric analysis. METHODS: Relevant original English language articles were retrieved from the Science Citation Index Expanded of the Web of Science Core Collection database, from inception to 31 December 2022. Full records and related cited references from all the documents were collected and analyzed. RESULTS: A total of 16368 authors from 3379 institutions in 83 countries/regions contributed to 2916 documents that were published in 712 academic journals. Annual publication output followed exponential growth since 2008. The United States, the University of Pittsburgh, and the American Journal of Physiology-Renal Physiology were the most productive countries, institutions, and journals in terms of research outputs, respectively. The area of interest has shifted from neutrophil gelatinase-associated lipocalin, cell cycle, and tubular damage toward sepsis and COVID-19. Apoptosis, inflammation, and chronic kidney disease have become popular in recent years, and studies on ferroptosis, machine learning, COVID-19, and renal fibrosis will be the focus of future research. IMPLICATIONS: This bibliometric study suggests that future research on AKI biomarkers would focus on ferroptosis, renal fibrosis and COVID-19. Artificial intelligence, such as machine learning, maybe the most promising direction for the discovery and validation of AKI biomarkers.

PEEP application during mechanical ventilation contributes to fibrosis in the diaphragm.

BACKGROUND: Positive end-expiratory airway pressure (PEEP) is a potent component of management for patients receiving mechanical ventilation (MV). However, PEEP may cause the development of diaphragm remodeling, making it difficult for patients to be weaned from MV. The current study aimed to explore the role of PEEP in VIDD. METHODS: Eighteen adult male New Zealand rabbits were divided into three groups at random: nonventilated animals (the CON group), animals with volume-assist/control mode without/ with PEEP 8 cmH2O (the MV group/ the MV + PEEP group) for 48 h with mechanical ventilation. Ventilator parameters and diaphragm were collected during the experiment for further analysis. RESULTS: There was no difference among the three groups in arterial blood gas and the diaphragmatic excursion during the experiment. The tidal volume, respiratory rate and minute ventilation were similar in MV + PEEP group and MV group. Airway peak pressure in MV + PEEP group was significantly higher than that in MV group (p < 0.001), and mechanical power was significantly higher (p < 0.001). RNA-seq showed that genes associated with fibrosis were enriched in the MV + PEEP group. This results were further confirmed on mRNA expression. As shown by Masson's trichrome staining, there was more collagen fiber in the MV + PEEP group than that in the MV group (p = 0.001). Sirius red staining showed more positive staining of total collagen fibers and type I/III fibers in the MV + PEEP group (p = 0.001; p = 0.001). The western blot results also showed upregulation of collagen types 1A1, III, 6A1 and 6A2 in the MV + PEEP group compared to the MV group (p < 0.001, all). Moreover, the positive immunofluorescence of COL III in the MV + PEEP group was more intense (p = 0.003). Furthermore, the expression of TGF-ß1, one of the most potent fibrogenic factors, was upregulated at both the mRNA and protein levels in the MV + PEEP group (mRNA: p = 0.03; protein: p = 0.04). CONCLUSIONS: We demonstrated that PEEP application for 48 h in mechanically ventilated rabbits will cause collagen deposition and fibrosis in the diaphragm. Moreover, activation of the TGF-ß1 signaling pathway and myofibroblast differentiation may be the potential mechanism of this diaphragmatic fibrosis. These findings might provide novel therapeutic targets for PEEP application-induced diaphragm dysfunction.

Airway Pressure Release Ventilation Mode Improves Circulatory and Respiratory Function in Patients After Cardiopulmonary Bypass, a Randomized Trial.

IMPORTANCE: Postoperative pulmonary complications and cardiovascular complications are major causes of morbidity, mortality, and resource utilization in cardiac surgery patients. OBJECTIVES: To investigate the effects of airway pressure release ventilation (APRV) on respiration and hemodynamics in post cardiac surgery patients. MAIN OUTCOMES AND MEASURES: A single-center randomized control trial was performed. In total, 138 patients undergoing cardiopulmonary bypass were prospectively screened. Ultimately 39 patients met the inclusion criteria and were randomized into two groups: 19 patients were managed with pressure control ventilation (PCV) and 20 patients were managed with APRV. Respiratory mechanics after 4 h, hemodynamics within the first day, and Chest radiograph score (CRS) and blood gasses within the first three days were recorded and compared. RESULTS: A higher cardiac index (3.1 ± 0.7 vs. 2.8 ± 0.8 L⋅min-1⋅m2; p < 0.05), and shock volume index (35.4 ± 9.2 vs. 33.1 ± 9.7 ml m-2; p < 0.05) were also observed in the APRV group after 4 h as well as within the first day (p < 0.05). Compared to the PCV group, the PaO2/FiO2 was significantly higher after 4 h in patients of APRV group (340 ± 97 vs. 301 ± 82, p < 0.05) and within the first three days (p < 0.05) in the APRV group. CRS revealed less overall lung injury in the APRV group (p < 0.001). The duration of mechanical ventilation and ICU length of stay were not significantly (p = 0.248 and 0.424, respectively). CONCLUSIONS AND RELEVANCE: Compared to PCV, APRV may be associated with increased cardiac output improved oxygenation, and decreased lung injury in postoperative cardiac surgery patients.

gB co-immunization with GP96 enhances pulmonary-resident CD8 T cells and exerts a long-term defence against MCMV pneumonitis.

Human cytomegalovirus (HCMV) infection in the respiratory tract leads to pneumonitis in immunocompromised hosts without available vaccine. Considering cytomegalovirus (CMV) mainly invades through the respiratory tract, CMV-specific pulmonary mucosal vaccine development that provides a long-lasting protection against CMV challenge gains our attention. In this study, N-terminal domain of GP96 (GP96-NT) was used as a mucosal adjuvant to enhance the induction of pulmonary-resident CD8 T cells elicited by MCMV glycoprotein B (gB) vaccine. Mice were intranasally co-immunized with 50 µg pgB and equal amount of pGP96-NT vaccine 4 times at 2-week intervals, and then i.n. challenged with MCMV at 16 weeks after the last immunization. Compared with pgB immunization alone, co-immunization with pgB/pGP96-NT enhanced a long-lasting protection against MCMV pneumonitis by significantly improved pneumonitis pathology, enhanced bodyweight, reduced viral burdens and increased survival rate. Moreover, the increased CD8 T cells were observed in lung but not spleen from pgB/pGP96-NT co-immunized mice. The increments of pulmonary CD8 T cells might be mainly due to non-circulating pulmonary-resident CD8 T-cell subset expansion but not circulating CD8 T-cell populations that home to inflammation site upon MCMV challenge. Finally, the deterioration of MCMV pneumonitis by depletion of pulmonary site-specific CD8 T cells in mice that were pgB/pGP96-NT co-immunization might be a clue to interpret the non-circulating pulmonary-resident CD8 T subset expansion. These data might uncover a promising long-lasting prophylactic vaccine strategy against MCMV-induced pneumonitis.

Lung Mechanics of Mechanically Ventilated Patients With COVID-19: Analytics With High-Granularity Ventilator Waveform Data.

Background: Lung mechanics during invasive mechanical ventilation (IMV) for both prognostic and therapeutic implications; however, the full trajectory lung mechanics has never been described for novel coronavirus disease 2019 (COVID-19) patients requiring IMV. The study aimed to describe the full trajectory of lung mechanics of mechanically ventilated COVID-19 patients. The clinical and ventilator setting that can influence patient-ventilator asynchrony (PVA) and compliance were explored. Post-extubation spirometry test was performed to assess the pulmonary function after COVID-19 induced ARDS. Methods: This was a retrospective study conducted in a tertiary care hospital. All patients with IMV due to COVID-19 induced ARDS were included. High-granularity ventilator waveforms were analyzed with deep learning algorithm to obtain PVAs. Asynchrony index (AI) was calculated as the number of asynchronous events divided by the number of ventilator cycles and wasted efforts. Mortality was recorded as the vital status on hospital discharge. Results: A total of 3,923,450 respiratory cycles in 2,778 h were analyzed (average: 24 cycles/min) for seven patients. Higher plateau pressure (Coefficient: -0.90; 95% CI: -1.02 to -0.78) and neuromuscular blockades (Coefficient: -6.54; 95% CI: -9.92 to -3.16) were associated with lower AI. Survivors showed increasing compliance over time, whereas non-survivors showed persistently low compliance. Recruitment maneuver was not able to improve lung compliance. Patients were on supine position in 1,422 h (51%), followed by prone positioning (499 h, 18%), left positioning (453 h, 16%), and right positioning (404 h, 15%). As compared with supine positioning, prone positioning was associated with 2.31 ml/cmH2O (95% CI: 1.75 to 2.86; p < 0.001) increase in lung compliance. Spirometry tests showed that pulmonary functions were reduced to one third of the predicted values after extubation. Conclusions: The study for the first time described full trajectory of lung mechanics of patients with COVID-19. The result showed that prone positioning was associated with improved compliance; higher plateau pressure and use of neuromuscular blockades were associated with lower risk of AI.

Evaluation of fish freshness using impedance spectroscopy based on the characteristic parameter of orthogonal direction difference.

BACKGROUND: As a nondestructive testing technology, electrochemical impedance spectroscopy (EIS) has been applied to evaluate food quality because of its features of rapidity, low cost, nondestructiveness and portability. However, fish freshness evaluation based on existing EIS technology is affected by the differences of individual biological samples. In this study, the difference of electrical properties between two orthogonal directions was extracted to develop a new freshness indicator. A real part orthogonal direction difference parameter set (RODDS) was used to establish a prediction model for total volatile basic nitrogen (TVB-N). RESULTS: Compared with the traditional parameter of EIS, coefficient of determination between RODDS and TVB-N increased from 0.55 to 0.71 for the calibration group, and root mean squared error between predicted and measured values of TVB-N decreased from 5.46 to 3.81 for the test group. CONCLUSIONS: The results implied that RODDS could effectively offset individual differences in basic electrical properties and improve the TVB-N prediction accuracy in practical application scenarios with samples from multiple origins. The proposed method may provide a new idea for the development and improvement of EIS-based portable testing devices for fish and meat. © 2020 Society of Chemical Industry.

Practice pattern of aerosol therapy among patients undergoing mechanical ventilation in mainland China: A web-based survey involving 447 hospitals.

BACKGROUND AND OBJECTIVE: Aerosol therapies are widely used for mechanically ventilated patients. However, the practice pattern of aerosol therapy in mainland China remains unknown. This study aimed to determine the current practice of aerosol therapy in mainland China. METHODS: A web-based survey was conducted by the China Union of Respiratory Care (CURC) from August 2018 to January 2019. The survey was disseminated via Email or WeChat to members of CURC. A questionnaire comprising 16 questions related to hospital information and 12 questions related to the practice of aerosol therapy. Latent class analysis was employed to identify the distinct classes of aerosol therapy practice. MAIN RESULTS: A total of 693 valid questionnaires were returned by respiratory care practitioners from 447 hospitals. Most of the practitioners used aerosol therapy for both invasive mechanical ventilation (90.8%) and non-invasive mechanical ventilation (91.3%). Practitioners from tertiary care centers were more likely to use aerosol therapy compared with those from non-tertiary care centers (91.9% vs. 85.4%, respectively; p = 0.035). The most commonly used drugs for aerosol therapy were bronchodilators (64.8%) followed by mucolytic agents (44.2%), topical corticosteroids (43.4%) and antibiotics (16.5%). The ultrasonic nebulizer (48.3%) was the most commonly used followed by the jet nebulizer (39.2%), the metered dose inhaler (15.4%) and the vibrating mesh nebulizer (14.6%). Six latent classes were identified via latent class analysis. Class 1 was characterized by the aggressive use of aerosol therapy without a standard protocol, while class 3 was characterized by the absence of aerosol therapy. CONCLUSIONS: Substantial heterogeneity among institutions with regard to the use of aerosol therapy was noted. The implementation of aerosol therapy during mechanical ventilation was inconsistent in light of recent practice guidelines. Additional efforts by the CURC to improve the implementation of aerosol therapy in mainland China are warranted.

High-precision extraction and concentration detection of airborne disease microorganisms based on microfluidic chip.

Accurate monitoring of the content of specific disease micro-organisms in the air is one of the key technologies for early warning of airborne diseases. Based on the principle of aerosol particle motion in the microenvironment, this paper proposes a microfluidic chip method for accurately extracting diseased micro-organisms directly from the gas stream. The chip consists of a two-stage coupling of parallel double-sheath flow focusing and radial sheath flow acceleration. Considering the case of extracting mold spores (near spherical shape, average particle size 6 µ m) and strawberry gray mold spores (near spherical shape, average particle size 10 µ m) from the mixture (concentration of the mixture is about 3.4 × 10 8 /ml), the performance of the chip was evaluated using two indicators: extraction rate and purity. The results showed that the extraction rates of mold spores and gray mildew spores were 89% and 76% and the purges were 98% and 87%, respectively, achieving high-purity and accurate extraction of fungal spores and greatly improving the detection accuracy. It could be used as the development basis of microbial sensor for the early rapid detection of crop fungal diseases.

[Advances in respiratory assessment and treatment in children undergoing invasive mechanical ventilation].

The widespread use of mechanical ventilation technology has contributed to the successful treatment of many children with respiratory failure. At the same time, forced ventilation and changes in normal respiratory physiology and mechanics may lead to respiratory dysfunction and decreased airway clearance ability. Therefore, how to perform a comprehensive and accurate respiratory function assessment, conduct appropriate respiratory function rehabilitation, perform extubation as soon as possible, and shorten the duration of mechanical ventilation based on the children's own physiological characteristics, is a focus of the research on effective weaning from mechanical ventilation in children with severe conditions. This article reviews the advances in the respiratory function assessment and treatment methods in children undergoing invasive mechanical ventilation.

Effect of Nebulizer Location and Spontaneous Breathing on Aerosol Delivery During Airway Pressure Release Ventilation in Bench Testing.

BACKGROUND: Airway pressure release ventilation (APRV) maintains a sustained airway pressure over a large proportion of the respiratory cycle, and has a long inspiratory time at high pressure. The purpose of this study was to determine the influence of the APRV with and without spontaneous breathing on albuterol aerosol delivery with a continuous vibrating-mesh nebulizer (VMN) placed at different positions on an adult lung model of invasive mechanical ventilation. METHODS: An adult lung model was assembled by connecting a ventilator with a dual-limb circuit to an 8-mm inner diameter endotracheal tube (ETT) and collecting filter attached to a test lung with set compliance of 0.1 L/cmH2O and resistance of 0.5 cmH2O/(L·s). Four ventilator modes were compared: pressure control ventilation (PCV) with no bias flow, PCV with bias flow of 6 L/min (PCVBF6), APRV with no spontaneous breaths (APRV), and APRV with spontaneous breath trigger (APRVs). Peak inspiratory pressure, peak end-expiratory pressure, aerosol dose, and nebulization time were similar for all modes. The VMN was placed (1) between Y-piece and inspiratory limb, (2) at the gas outlet of a heated humidifier, and (3) at the gas inlet of a heated humidifier. Albuterol sulfate (5 mg/2.5 mL) was administered with each run and collected on a filter distal to the ETT. Deposited drug was eluted from each filter (purified water) and analyzed by UV spectrophotometry at 276 nm. Analysis of variance [general linear model (GLM) multivariate] was performed using the linear model of multiple variables, significance at p < 0.05. RESULTS: Albuterol (in micrograms, mean ± standard deviation) delivered was higher with VMN placed at the gas inlet of the humidifier with each mode of ventilation (p < 0.01). APRVs has the highest albuterol delivery followed by PCV, PCVBF6, and APRV (1706.2 ± 60.9 µg vs. 1490.6 ± 61.1 µg vs. 1182.3 ± 61.4 µg vs. 1153.1 ± 99.7 µg, respectively, p < 0.001). The minute volume was positively correlated with the inhaled albuterol dose. CONCLUSIONS: Spontaneous breathing increased the albuterol delivery during APRV, compared with APRV alone and PCV modes. Placing the nebulizer proximal to the ventilator was more efficient for all modes tested.

Rational lung tissue and animal models for rapid breath tests to determine pneumonia and pathogens.

OBJECTIVE: This study works to develop novel models that may be adopted for earlier non-invasive breathomics tests to determine pneumonia pathogens. METHODS: Two types of pneumonia models were created, both in vitro and in vivo. Paraneoplasm lung tissue and specific pathogen-free (SPF) rabbits were adopted and separately challenged with sterile saline solution control or three pathogens: Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. After inoculation, headspace air or exhaled air were absorbed by solid phase micro-extraction (SPME) fibers and subsequently analyzed with gas chromatograph Mass Spectrometer (GCMS). RESULTS: Pneumonia and pathogen-specific discriminating VOC patterns (1H-Pyrrole-3-carbonitrile, Diethyl phthalate, Cedrol, Decanoic acid, Cyclohexane, Diisooctyl phthalate) were determined. CONCLUSION: Our study successfully generated nosocomial pneumonia models for pneumonia diagnosis and pathogen-discriminating breath tests. The tests may allow for earlier pneumonia and pathogen diagnoses, and may transfer empirical therapy to targeted therapy earlier, thus improving clinical outcomes.

The predictive value of serial changes in diaphragm function during the spontaneous breathing trial for weaning outcome: a study protocol.

INTRODUCTION: There is a variety of tools being used in clinical practice for the prediction of weaning success from mechanical ventilation. However, their diagnostic performances are less than satisfactory. The purpose of this study is to investigate the value of serial changes in diaphragm function measured by ultrasound during the spontaneous breathing trial (SBT) as a weaning predictor. METHODS AND ANALYSIS: This is a prospective observational study conducted in a 10-bed medical emergency intensive care unit (EICU) in a university-affiliated hospital. The study will be performed from November 2016 to December 2017. All patients in the EICU who are expected to have mechanical ventilation for more than 48 hours through endotracheal tube are potentially eligible for this study. Patients will be included if they fulfil the criteria for SBT. All enrolled patients will be ventilated with an Evita-4 by using volume assist control mode prior to SBT. Positive end-expiratory pressure (PEEP) will be set to 5 cmH2O and fractional inspired oxygen (FiO2) will be set to a value below 0.5 that guarantees oxygen saturation by pulse oximetry (SpO2) greater than 90%. Enrolled patients will undergo SBT for 2 hours in semirecumbent position. During the SBT, the patients will breathe through the ventilator circuit by using flow triggering (2 L/min) with automatic tube compensation of 100% and 5 cmH2O PEEP. The FiO2 will be set to the same value as used before SBT. If the patients fail to tolerate the SBT, the trial will be discontinued immediately and the ventilation mode will be switched to that used before the trial. Patients who pass the 2-hour SBT will be extubated. Right diaphragm excursion and bilateral diaphragm thickening fraction will be measured by ultrasonography during spontaneous breathing. Images will be obtained immediately prior to the SBT, and at 5, 30, 60, 90 and 120 min after the initiation of SBT. Rapid shallow breathing index will be simultaneously calculated at the bedside by a respiratory nurse. ETHICS AND DISSEMINATION: The study protocol is approved by the ethics committee of Sir Run Run Shaw Hospital, an affiliate of Zhejiang University, Medical College. The results will be published in a peer-reviewed journal and shared with the worldwide medical community. TRIAL REGISTRATION NUMBER: ISRCTN42917473; Pre-results.

High-Level Pressure Support Ventilation Attenuates Ventilator-Induced Diaphragm Dysfunction in Rabbits.

BACKGROUND: The effects of different modes of mechanical ventilation in the same ventilatory support level on ventilator-induced diaphragm dysfunction onset were assessed in healthy rabbits. METHODS: Twenty New Zealand rabbits were randomly assigned to 4 groups (n = 5 in each group). Group 1: no mechanical ventilation; group 2: controlled mechanical ventilation (CMV) for 24 hours; group 3: assist/control ventilation (A/C) mode for 24 hours; group 4: high-level pressure support ventilation (PSV) mode for 24 hours. Heart rate, mean arterial blood pressure, PH, partial pressure of arterial oxygen/fraction of inspired oxygen and partial pressure of arterial carbon dioxide were monitored and diaphragm electrical activity was analyzed in the 4 groups. Caspase-3 was evaluated by protein analysis and diaphragm ultra structure was assessed by electron microscopy. RESULTS: The centroid frequency and the ratio of high frequency to low frequency were significantly reduced in the CMV, A/C and PSV groups (P < 0.001). The percent change in centroid frequency was significantly lower in the PSV group than in the CMV and A/C groups (P = 0.001 and P = 0.028, respectively). Electromyography of diaphragm integral amplitude decreased by 90% ± 1.48%, 67.8% ± 3.13% and 70.2% ± 4.72% in the CMV, A/C and PSV groups, respectively (P < 0.001). Caspase-3 protein activation was attenuated in the PSV group compared with the CMV and A/C groups (P = 0.035 and P = 0.033, respectively). Irregular swelling of mitochondria along with fractured and fuzzy cristae was observed in the CMV group, whereas mitochondrial cristae were dense and rich in the PSV group. The mitochondrial injury scores (Flameng scores) in the PSV group were the lowest among the 3 ventilatory groups (0.93 ± 0.09 in PSV versus 2.69 ± 0.05 in the CMV [P < 0.01] and PSV versus A/C groups [2.02 ± 0.08, P < 0.01]). CONCLUSIONS: The diaphragm myoelectric activity was reduced in the PSV group, although excessive oxidative stress and ultra-structural changes of diaphragm were found. However, partial diaphragm electrical activity was retained and diaphragm injury was minimized using the PSV mode.