Risk factors of in-hospital mortality and discriminating capacity of NIVO score in exacerbations of COPD requiring noninvasive ventilation.

BACKGROUND: Noninvasive mechanical ventilation (NIV) is recommended as the initial mode of ventilation to treat acute respiratory failure in patients with AECOPD. The Noninvasive Ventilation Outcomes (NIVO) score has been proposed to evaluate the prognosis in patients with AECOPD requiring assisted NIV. However, it is not validated in Chinese patients. METHODS: We used data from the MAGNET AECOPD Registry study, which is a prospective, noninterventional, multicenter, real-world study conducted between September 2017 and July 2021 in China. Data for the potential risk factors of mortality were collected and the NIVO score was calculated, and the in-hospital mortality was evaluated using the NIVO risk score. RESULTS: A total of 1164 patients were included in the study, and 57 patients (4.9%) died during their hospital stay. Multiple logistic regression analysis revealed that age ≥75 years, DBP <60 mmHg, Glasgow Coma Scale ≤14, anemia and BUN >7 mmol/L were independent predictors of in-hospital mortality. The in-hospital mortality was associated with an increase in the risk level of NIVO score and the difference was statistically significant (p < .001). The NIVO risk score showed an acceptable accuracy for predicting the in-hospital mortality in AECOPD requiring assisted NIV (AUC: 0.657, 95% CI: 0.584-0.729, p < .001). CONCLUSION: Our findings identified predictors of mortality in patients with AECOPD receiving NIV, providing useful information to identify severe patients and guide the management of AECOPD. The NIVO score showed an acceptable predictive value for AECOPD receiving NIV in Chinese patients, and additional studies are needed to develop and validate predictive scores based on specific populations.

Characteristics, treatments, in-hospital and long-term outcomes among inpatients with acute exacerbation of chronic obstructive pulmonary disease in China: sex differences in a large cohort study.

BACKGROUND: Data related to the characteristics, treatments and clinical outcomes of acute exacerbation of chronic obstructive pulmonary disease (AECOPD) patients in China are limited, and sex differences are still a neglected topic. METHODS: The patients hospitalized for AECOPD were prospectively enrolled from ten medical centers in China between September 2017 and July 2021. Patients from some centers received follow-up for 3 years. Data regarding the characteristics, treatments and in-hospital and long-term clinical outcomes from male and female AECOPD patients included in the cohort were analyzed and compared. RESULTS: In total, 14,007 patients with AECOPD were included in the study, and 11,020 (78.7%) were males. Compared with males, female patients were older (74.02 ± 10.79 vs. 71.86 ± 10.23 years, P < 0.001), and had more comorbidities (2.22 ± 1.64 vs. 1.73 ± 1.56, P < 0.001), a higher frequency of altered mental status (5.0% vs. 2.9%, P < 0.001), lower diastolic blood pressure (78.04 ± 12.96 vs. 79.04 ± 12.47 mmHg, P < 0.001). In addition, there were also significant sex differences in a range of laboratory and radiographic findings. Females were more likely to receive antibiotics, high levels of respiratory support and ICU admission than males. The in-hospital and 3-year mortality were not significantly different between males and females (1.4% vs. 1.5%, P = 0.711; 35.3% vs. 31.4%, P = 0.058), while female smokers with AECOPD had higher in-hospital mortality than male smokers (3.3% vs. 1.2%, P = 0.002) and male smokers exhibited a trend toward higher 3-year mortality compared to female smokers (40.7% vs. 33.1%, P = 0.146). CONCLUSIONS: In AECOPD inpatients, females and males had similar in-hospital and long-term survival despite some sex differences in clinical characteristics and treatments, but female smokers had significantly worse in-hospital outcomes than male smokers. CLINICAL TRIAL REGISTRATION: Retrospectively registered, registration number is ChiCTR2100044625, date of registration 21/03/2021. URL: http://www.chictr.org.cn/showproj.aspx?proj=121626 .

Kinesin light chain 1 stabilizes insulin receptor substrate 1 to regulate the IGF-1-AKT signaling pathway during myoblast differentiation.

The IGF signaling pathway plays critical role in regulating skeletal myogenesis. We have demonstrated that KIF5B, the heavy chain of kinesin-1 motor, promotes myoblast differentiation through regulating IGF-p38MAPK activation. However, the roles of the kinesin light chain (Klc) in IGF pathway and myoblast differentiation remain elusive. In this study, we found that Klc1 was upregulated during muscle regeneration and downregulated in senescence mouse muscles and dystrophic muscles from mdx (X-linked muscular dystrophic) mice. Gain- and loss-of-function experiments further displayed that Klc1 promotes AKT-mTOR activity and positively regulates myogenic differentiation. We further identified that the expression levels of IRS1, the critical node of IGF-1 signaling, are downregulated in Klc1-depleted myoblasts. Coimmunoprecipitation study revealed that IRS1 interacted with the 88-154 amino acid sequence of Klc1 via its PTB domain. Notably, the reduced Klc1 levels were found in senescence and osteoporosis skeletal muscle samples from both mice and human. Taken together, our findings suggested a crucial role of Klc1 in the regulation of IGF-AKT pathway during myogenesis through stabilizing IRS1, which might ultimately influence the development of muscle-related disorders.

A simple clinical risk score (ABCDMP) for predicting mortality in patients with AECOPD and cardiovascular diseases.

BACKGROUND: The morbidity and mortality among hospital inpatients with AECOPD and CVDs remains unacceptably high. Currently, no risk score for predicting mortality has been specifically developed in patients with AECOPD and CVDs. We therefore aimed to derive and validate a simple clinical risk score to assess individuals' risk of poor prognosis. STUDY DESIGN AND METHODS: We evaluated inpatients with AECOPD and CVDs in a prospective, noninterventional, multicenter cohort study. We used multivariable logistic regression analysis to identify the independent prognostic risk factors and created a risk score model according to patients' data from a derivation cohort. Discrimination was evaluated by the area under the receiver-operating characteristic curve (AUC), and calibration was assessed by the Hosmer-Lemeshow goodness-of-fit test. The model was validated and compared with the BAP-65, CURB-65, DECAF and NIVO models in a validation cohort. RESULTS: We derived a combined risk score, the ABCDMP score, that included the following variables: age > 75 years, BUN > 7 mmol/L, consolidation, diastolic blood pressure ≤ 60 mmHg, mental status altered, and pulse > 109 beats/min. Discrimination (AUC 0.847, 95% CI, 0.805-0.890) and calibration (Hosmer‒Lemeshow statistic, P = 0.142) were good in the derivation cohort and similar in the validation cohort (AUC 0.811, 95% CI, 0.755-0.868). The ABCDMP score had significantly better predictivity for in-hospital mortality than the BAP-65, CURB-65, DECAF, and NIVO scores (all P < 0.001). Additionally, the new score also had moderate predictive performance for 3-year mortality and can be used to stratify patients into different management groups. CONCLUSIONS: The ABCDMP risk score could help predict mortality in AECOPD and CVDs patients and guide further clinical research on risk-based treatment. CLINICAL TRIAL REGISTRATION: Chinese Clinical Trail Registry NO.:ChiCTR2100044625; URL: http://www.chictr.org.cn/showproj.aspx?proj=121626 .

Validation of the Rome Severity Classification of Chronic Obstructive Pulmonary Disease Exacerbation: A Multicenter Cohort Study.

Background: The Rome severity classification is an objective assessment tool for the severity of acute exacerbations of chronic obstructive pulmonary disease (AECOPD) based on readily measurable variables but has not been widely validated. The aim of this study is to evaluate the validity of the Rome classification in distinguishing the severity of AECOPD based on short-term mortality and other adverse outcomes. Methods: The Rome severity classification was applied to a large multicenter cohort of inpatients with AECOPD. Differences in clinical features, in-hospital and 60-day mortality, intensive care unit (ICU) admission, mechanical ventilation (MV) and invasive mechanical ventilation (IMV) usage were compared among the mild, moderate and severe AECOPD according to the Rome proposal. Moreover, univariate logistic analysis and Kaplan Meier survival analysis were also performed to find the association between the Rome severity classification and those adverse outcomes. Results: A total of 7712 patients hospitalized for AECOPD were included and classified into mild (41.88%), moderate (40.33%), or severe (17.79%) group according to the Rome proposal. The rate of ICU admission (6.4% vs 12.0% vs 14.9%, P <0.001), MV (11.7% vs 33.7% vs 45.3%, P <0.001) and IMV (1.4% vs 6.8% vs 8.9%, P <0.001) increased significantly with the increase of severity classification from mild to moderate to severe AECOPD. The 60-day mortality was higher in the moderate or severe group than in the mild group (3.5% vs 1.9%, 4.3% vs 1.9%, respectively, P <0.05) but showed no difference between the moderate and severe groups (2.6% vs 2.5%, P >0.05), results for in-hospital mortality showed the same trends. Similar findings were observed by univariate logistic analysis and survival analysis. Conclusion: Rome severity classification demonstrated excellent performance in predicting ICU admission and the need for MV or IMV, but how it performs in differentiating short-term mortality still needs to be confirmed.

Preserved Ratio Impaired Spirometry and COPD Accelerate Frailty Progression: Evidence From a Prospective Cohort Study.

BACKGROUND: COPD has been found to be associated with frailty. However, longitudinal evidence for associations of COPD with frailty progression is inadequate. Furthermore, recent studies revealed a new phenotype of lung function impairment: preserved ratio impaired spirometry (PRISm) findings. Associations of PRISm findings and their transitions with frailty progression are unclear. RESEARCH QUESTION: What are the associations of PRISm findings, transitions of PRISm findings, and COPD with frailty progression? STUDY DESIGN AND METHODS: To analyze the associations of PRISm findings and COPD with frailty progression, 5,901 patients were included from the English Longitudinal Study of Ageing. Patients were classified into three lung function patterns of normal spirometry (NS) findings, PRISm findings, and COPD. Frailty progression was assessed by repeated measurements of the frailty index (FI) during follow-up. Among these 5,901 patients, 3,765 patients were included to analyze the associations of PRISm findings transitions with frailty progression. PRISm findings transitions were assessed based on the changes of lung function patterns after a 4-year interval. Linear mixed-effect models were used for statistical analyses. RESULTS: The median follow-up periods were 9.5 years for the analyses of PRISm findings and COPD with frailty progression and 5.8 years for PRISm findings transitions with frailty progression. When compared with participants with NS findings, patients with PRISm findings and COPD demonstrated accelerated FI progression with additional annual increases of 0.301 (95% CI, 0.211-0.392; P < .001) and 0.172 (95% CI, 0.102-0.242; P < .001), respectively. Patients who transitioned from NS findings to PRISm findings also demonstrated accelerated FI progression when compared with those with stable NS findings (ß = 0.242; 95% CI, 0.008-0.476; P = .042). However, no accelerated FI progression was found in patients with PRISm findings who transitioned to NS findings (ß = 0.119; 95% CI, -0.181 to 0.418; P = .438). INTERPRETATION: Our findings indicate that PRISm findings and COPD are associated with accelerated frailty progression. Further studies are needed to elucidate the causality of the association of PRISm findings and COPD with frailty.

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.

Estimated cardiorespiratory fitness and incident risk of cardiovascular disease in China.

BACKGROUND: Limited evidence is available on the association between estimated cardiorespiratory fitness (e-CRF) and incidence of cardiovascular disease (CVD) in Chinese population. METHODS: A total of 10,507 adults including 5084 men (48.4%) and 5423 (51.6%) women with a median age of 56.0 (25% quantile: 49, 75% quantile 63) years from the China Health and Retirement Longitudinal Study (CHARLS) was recruited in 2011 as baseline. The CVD incident events were followed-up until 2018. e-CRF was calculated from sex-specific longitudinal non-exercise equations and further grouped into quartiles. Cox proportional models were used to calculate hazard ratio (HR) and 95% confidence interval (CI) for incidence risks of CVD, heart disease and stroke. RESULTS: During a median follow-up of 7 years, a total of 1862 CVD, 1409 heart disease and 612 stroke events occurred. In fully adjusted models, each one MET increment of e-CRF was associated with lower risk of CVD (HR = 0.91, 95%CI = 0.85-0.96 for males, HR = 0.87, 95%CI = 0.81-0.94 for females). Compared with the Quartile (Q)1 group, the HRs (95%CI) of the Q2, Q3 and Q4 groups were 0.84 (0.63-1.03), 0.72 (0.57-0.91) and 0.66 (0.51-0.87) for CVD in males. Females had HRs of 0.79 (0.66-0.96) in Q2, 0.71 (0.57-0.88) in Q3 and 0.58 (0.45-0.75) in Q4 for CVD. The associations between e-CRF and heart disease and stroke were slightly weaker than that for CVD in both males and females. CONCLUSIONS: Higher e-CRF decreases the incident risk of CVD, heart disease and stroke.

Elevated BUN Upon Admission as a Predictor of in-Hospital Mortality Among Patients with Acute Exacerbation of COPD: A Secondary Analysis of Multicenter Cohort Study.

Background: High blood urea nitrogen (BUN) is observed in a subset of patients with acute exacerbation of COPD (AECOPD) and may be linked to clinical outcome, but findings from previous studies have been inconsistent. Methods: We performed a retrospective analysis of patients prospectively enrolled in the MAGNET AECOPD Registry study (ChiCTR2100044625). Receiver operating characteristic (ROC) was used to determine the level of BUN that discriminated survivors and non-survivors. Univariate and multivariate Cox proportional hazards regression analyses were performed to assess the impact of BUN on adverse outcomes. Results: Overall, 13,431 consecutive inpatients with AECOPD were included in this study, of whom 173 died, with the mortality of 1.29%. The non-survivors had higher levels of BUN compared with the survivors [9.5 (6.8-15.3) vs 5.6 (4.3-7.5) mmol/L, P < 0.001]. ROC curve analysis showed that the optimal cutoff of BUN level was 7.30 mmol/L for in-hospital mortality (AUC: 0.782; 95% CI: 0.748-0.816; P < 0.001). After multivariate analysis, BUN level ≥7.3 mmol/L was an independent risk factor for in-hospital mortality (HR = 2.099; 95% CI: 1.378-3.197, P = 0.001), also for invasive mechanical ventilation (HR = 1.540; 95% CI: 1.199-1.977, P = 0.001) and intensive care unit admission (HR = 1.344; 95% CI: 1.117-1.617, P = 0.002). Other independent prognostic factors for in-hospital mortality including age, renal dysfunction, heart failure, diastolic blood pressure, pulse rate, PaCO2 and D-dimer. Conclusion: BUN is an independent risk factor for in-hospital mortality in inpatients with AECOPD and may be used to identify serious (or severe) patients and guide the management of AECOPD. Clinical Trial Registration: MAGNET AECOPD; Chinese Clinical Trail Registry NO.: ChiCTR2100044625; Registered March 2021, URL: http://www.chictr.org.cn/showproj.aspx?proj=121626.

Low diastolic blood pressure and adverse outcomes in inpatients with acute exacerbation of chronic obstructive pulmonary disease: A multicenter cohort study.

BACKGROUND: Although intensively studied in patients with cardiovascular diseases (CVDs), the prognostic value of diastolic blood pressure (DBP) has little been elucidated in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD). This study aimed to reveal the prognostic value of DBP in AECOPD patients. METHODS: Inpatients with AECOPD were prospectively enrolled from 10 medical centers in China between September 2017 and July 2021. DBP was measured on admission. The primary outcome was all-cause in-hospital mortality; invasive mechanical ventilation and intensive care unit (ICU) admission were secondary outcomes. Least absolute shrinkage and selection operator (LASSO) and multivariable Cox regressions were used to identify independent prognostic factors and calculate the hazard ratio (HR) and 95% confidence interval (CI) for adverse outcomes. RESULTS: Among 13,633 included patients with AECOPD, 197 (1.45%) died during their hospital stay. Multivariable Cox regression analysis showed that low DBP on admission (<70 mmHg) was associated with increased risk of in-hospital mortality (HR = 2.16, 95% CI: 1.53-3.05, Z = 4.37, P <0.01), invasive mechanical ventilation (HR = 1.65, 95% CI: 1.32-2.05, Z = 19.67, P <0.01), and ICU admission (HR = 1.45, 95% CI: 1.24-1.69, Z = 22.08, P <0.01) in the overall cohort. Similar findings were observed in subgroups with or without CVDs, except for invasive mechanical ventilation in the subgroup with CVDs. When DBP was further categorized in 5-mmHg increments from <50 mmHg to ≥100 mmHg, and 75 to <80 mmHg was taken as reference, HRs for in-hospital mortality increased almost linearly with decreased DBP in the overall cohort and subgroups of patients with CVDs; higher DBP was not associated with the risk of in-hospital mortality. CONCLUSION: Low on-admission DBP, particularly <70 mmHg, was associated with an increased risk of adverse outcomes among inpatients with AECOPD, with or without CVDs, which may serve as a convenient predictor of poor prognosis in these patients. CLINICAL TRIAL REGISTRATION: Chinese Clinical Trail Registry, No. ChiCTR2100044625.

Lung Recruitment Assessed by Electrical Impedance Tomography (RECRUIT): A Multicenter Study of COVID-19 Acute Respiratory Distress Syndrome.

Rationale: Defining lung recruitability is needed for safe positive end-expiratory pressure (PEEP) selection in mechanically ventilated patients. However, there is no simple bedside method including both assessment of recruitability and risks of overdistension as well as personalized PEEP titration. Objectives: To describe the range of recruitability using electrical impedance tomography (EIT), effects of PEEP on recruitability, respiratory mechanics and gas exchange, and a method to select optimal EIT-based PEEP. Methods: This is the analysis of patients with coronavirus disease (COVID-19) from an ongoing multicenter prospective physiological study including patients with moderate-severe acute respiratory distress syndrome of different causes. EIT, ventilator data, hemodynamics, and arterial blood gases were obtained during PEEP titration maneuvers. EIT-based optimal PEEP was defined as the crossing point of the overdistension and collapse curves during a decremental PEEP trial. Recruitability was defined as the amount of modifiable collapse when increasing PEEP from 6 to 24 cm H2O (ΔCollapse24-6). Patients were classified as low, medium, or high recruiters on the basis of tertiles of ΔCollapse24-6. Measurements and Main Results: In 108 patients with COVID-19, recruitability varied from 0.3% to 66.9% and was unrelated to acute respiratory distress syndrome severity. Median EIT-based PEEP differed between groups: 10 versus 13.5 versus 15.5 cm H2O for low versus medium versus high recruitability (P < 0.05). This approach assigned a different PEEP level from the highest compliance approach in 81% of patients. The protocol was well tolerated; in four patients, the PEEP level did not reach 24 cm H2O because of hemodynamic instability. Conclusions: Recruitability varies widely among patients with COVID-19. EIT allows personalizing PEEP setting as a compromise between recruitability and overdistension. Clinical trial registered with www.clinicaltrials.gov (NCT04460859).

Blood Eosinophils and Clinical Outcomes in Inpatients with Acute Exacerbation of Chronic Obstructive Pulmonary Disease: A Prospective Cohort Study.

Purpose: The prognostic value of blood eosinophils in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD) remains controversial. This study aimed to evaluate whether blood eosinophils could predict in-hospital mortality and other adverse outcomes in inpatients with AECOPD. Methods: The patients hospitalized for AECOPD were prospectively enrolled from ten medical centers in China. Peripheral blood eosinophils were detected on admission, and the patients were divided into eosinophilic and non-eosinophilic groups with 2% as the cutoff value. The primary outcome was all-cause in-hospital mortality. Results: A total of 12,831 AECOPD inpatients were included. The non-eosinophilic group was associated with higher in-hospital mortality than the eosinophilic group in the overall cohort (1.8% vs 0.7%, P < 0.001), the subgroup with pneumonia (2.3% vs 0.9%, P = 0.016) or with respiratory failure (2.2% vs 1.1%, P = 0.009), but not in the subgroup with ICU admission (8.4% vs 4.5%, P = 0.080). The lack of association still remained even after adjusting for confounding factors in subgroup with ICU admission. Being consistent across the overall cohort and all subgroups, non-eosinophilic AECOPD was also related to greater rates of invasive mechanical ventilation (4.3% vs 1.3%, P < 0.001), ICU admission (8.9% vs 4.2%, P < 0.001), and, unexpectedly, systemic corticosteroid usage (45.3% vs 31.7%, P < 0.001). Non-eosinophilic AECOPD was associated with longer hospital stay in the overall cohort and subgroup with respiratory failure (both P < 0.001) but not in those with pneumonia (P = 0.341) or ICU admission (P = 0.934). Conclusion: Peripheral blood eosinophils on admission may be used as an effective biomarker to predict in-hospital mortality in most AECOPD inpatients, but not in patients admitted into ICU. Eosinophil-guided corticosteroid therapy should be further studied to better guide the administration of corticosteroids in clinical practice.

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.

Comprehensive breathing variability indices enhance the prediction of extubation failure in patients on mechanical ventilation.

BACKGROUND AND OBJECTIVE: Despite the numerous studies on extubation readiness assessment for patients who are invasively ventilated in the intensive care unit, a 10-15% extubation failure rate persists. Although breathing variability has been proposed as a potential predictor of extubation failure, it is mainly assessed using simple statistical metrics applied to basic respiratory parameters. Therefore, the complex pattern of breathing variability conveyed by continuous ventilation waveforms may be underexplored. METHODS: Here, we aimed to develop novel breathing variability indices to predict extubation failure among invasively ventilated patients. First, breath-to-breath basic and comprehensive respiratory parameters were computed from continuous ventilation waveforms 1 h before extubation. Subsequently, the basic and advanced variability methods were applied to the respiratory parameter sequences to derive comprehensive breathing variability indices, and their role in predicting extubation failure was assessed. Finally, after reducing the feature dimensionality using the forward search method, the combined effect of the indices was evaluated by inputting them into the machine learning models, including logistic regression, random forest, support vector machine, and eXtreme Gradient Boosting (XGBoost). RESULTS: The coefficient of variation of the dynamic mechanical power per breath (CV-MPd[J/breath]) exhibited the highest area under the receiver operating characteristic curve (AUC) of 0.777 among the individual indices. Furthermore, the XGBoost model obtained the best AUC (0.902) by combining multiple selected variability indices. CONCLUSIONS: These results suggest that the proposed novel breathing variability indices can improve extubation failure prediction in invasively ventilated patients.

A cross-sectional survey on the lung ultrasound training and practice of respiratory therapists in mainland China.

PURPOSE: This national study aimed to investigate the lung ultrasound (LUS) training and practice of respiratory therapists (RTs) in mainland China. METHODS: A cross-sectional multicenter survey was conducted from May 22, 2021 to August 12, 2021, through online platforms. This survey included RTs in mainland China. The survey was divided into four sections: (1) demographic characteristics and basic information; (2) basic information about LUS training and practice; (3) LUS practice details; and (4) Other ultrasound training and practice. RESULTS: A total of 514 responses were received, and 494 valid responses were included in the analysis. 81.2% (401/494) participants' highest degree of education was a bachelor's degree, and 43.1% (213/494) participants were at level II in terms of job ranking. 99.2%(490/494) participants agreed that the RTs needed to learn lung ultrasound, but only 12.3% (61/494) participants had received a LUS training course. Further, 66.2% (327/494) experienced participants responded to Sect. 3. Most of RTs used LUS when the patient had hypoxia (265/327, 81%) or dyspnea (260/317, 79.5%); they also used it during spontaneous breathing trial(SBT) (191/327, 58.4%) or in prone position (177/327, 54.1%). The A-line (302/327, 92.4%), B-line (299/327, 91.4%), lung slide (263/327, 80.4%), and bat sign (259/327, 79.2%) were well known as LUS signs. Also, 30.6% (100/327) participants did not use the LUS protocol in their clinical practice, and only 25.4%(83/327) participants said they had used LUS scores. Moreover, 55.7% (182/327) participants frequently changed the respiratory therapy strategy according to LUS results. CONCLUSIONS: We should improve the number and workplace of RTs in mainland China in the future. We should also standardize the application of LUS practice and training for RTs in mainland China and establish corresponding certification pathways.

Superior Predictive Value of D-Dimer to the Padua Prediction Score for Venous Thromboembolism in Inpatients with AECOPD: A Multicenter Cohort Study.

Background: The optimal tool for risk prediction of venous thromboembolism (VTE) in inpatients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD) is still unknown. This study aimed to evaluate whether D-dimer could predict the risk of VTE in inpatients with AECOPD compared to the Padua Prediction Score (PPS). Methods: Inpatients with AECOPD were prospectively enrolled from seven medical centers in China between December 2018 and June 2020. On admission, D-dimer was detected, PPS was calculated for each patient, and the incidence of 2-month VTE was investigated. The receiver operating characteristic (ROC) curve was used to evaluate the predictive value of D-dimer and PPS on VTE development, and the best cut-off value for both methods was evaluated through the Youden index. Results: Among the 4468 eligible patients with AECOPD, 90 patients (2.01%) developed VTE within 2 months after admission. The area under the receiver operating characteristic curves (AUCs) of D-dimer for predicting VTE were significantly higher than those of the PPS both in the overall cohort (0.724, 95% CI 0.672-0.776 vs 0.620, 95% CI 0.562-0.679; P<0.05) and the subgroup of patients without thromboprophylaxis (0.747, 95% CI 0.695-0.799 vs 0.640, 95% CI 0.582-0.698; P<0.05). By calculating the Youden Index, the best cut-off value of D-dimer was determined to be 0.96 mg/L with an AUC of 0.689, which was also significantly better than that of the PPS with the best cut-off value of 2 (AUC 0.581, P=0.007). After the combination of D-dimer with PPS, the AUC (0.621) failed to surpass D-dimer alone (P=0.104). Conclusion: D-dimer has a superior predictive value for VTE over PPS in inpatients with AECOPD, which might be a better choice to guide thromboprophylaxis in inpatients with AECOPD due to its effectiveness and convenience. Clinical Trial Registration: Chinese Clinical Trail Registry NO. ChiCTR2100044625; URL: http://www.chictr.org.cn/showproj.aspx?proj=121626.

Identifying Novel Clusters of Patients With Prolonged Mechanical Ventilation Using Trajectories of Rapid Shallow Breathing Index.

Objective: Patients with prolonged mechanical ventilation (PMV) are comprised of a heterogeneous population, creating great challenges for clinical management and study design. The study aimed to identify subclusters of PMV patients based on trajectories of rapid shallow breathing index (RSBI), and to develop a machine learning model to predict the cluster membership based on baseline variables. Methods: This was a retrospective cohort study conducted in respiratory care center (RCC) at a tertiary academic medical center. The RCC referral criteria were patients with mechanical ventilation for at least 21 days with stable hemodynamic and oxygenation status. Patients admitted to the RCC from April 2009 to December 2020 were screened. Two-step clustering through linear regression modeling and k-means was employed to find clusters of the trajectories of RSBI. The number of clusters was chosen by statistical metrics and domain expertise. A gradient boosting machine (GBM) was trained, exploiting variables on RCC admission, to predict cluster membership. Results: A total of 1371 subjects were included in the study. Four clusters were identified: cluster A showed persistently high RSBI; cluster B was characterized by a constant low RSBI over time; Cluster C was characterized by increasing RSBI; and cluster D showed a declining RSBI. Cluster A showed the highest mortality rate (72%), followed by cluster D (63%), C (62%) and B (61%; p = 0.005 for comparison between 4 clusters). GBM was able to predict cluster membership with an accuracy of > 0.95 in ten-fold cross validation. Highly ranked variables for the prediction of clusters included thyroid-stimulating hormone (TSH), cortisol, platelet, free thyroxine (T4) and serum magnesium. Conclusions: Patients with PMV are composed of a heterogeneous population that can be classified into four clusters by using trajectories of RSBI. These clusters can be easily predicted with baseline clinical variables.

Phase separation of insulin receptor substrate 1 drives the formation of insulin/IGF-1 signalosomes.

As a critical node for insulin/IGF signaling, insulin receptor substrate 1 (IRS-1) is essential for metabolic regulation. A long and unstructured C-terminal region of IRS-1 recruits downstream effectors for promoting insulin/IGF signals. However, the underlying molecular basis for this remains elusive. Here, we found that the C-terminus of IRS-1 undergoes liquid-liquid phase separation (LLPS). Both electrostatic and hydrophobic interactions were seen to drive IRS-1 LLPS. Self-association of IRS-1, which was mainly mediated by the 301-600 region, drives IRS-1 LLPS to form insulin/IGF-1 signalosomes. Moreover, tyrosine residues of YXXM motifs, which recruit downstream effectors, also contributed to IRS-1 self-association and LLPS. Impairment of IRS-1 LLPS attenuated its positive effects on insulin/IGF-1 signaling. The metabolic disease-associated G972R mutation impaired the self-association and LLPS of IRS-1. Our findings delineate a mechanism in which LLPS of IRS-1-mediated signalosomes serves as an organizing center for insulin/IGF-1 signaling and implicate the role of aberrant IRS-1 LLPS in metabolic diseases.

Predictive Equations for Adult Pulmonary Function in Zhejiang Province, China.

Background: Accurate interpretation of lung function tests requires appropriate spirometry reference values derived from large-scale population-specific epidemiological surveys. The aim of this cross-sectional study was to establish normal spirometric values for the population of healthy, nonsmoking Han Chinese adults residing in Zhejiang province, China. Methods: We measured lung function parameters such as forced expiratory volume in 1 s, forced vital capacity, peak expiratory flow, maximal midexpiratory flow, and diffusion capacity for carbon monoxide and considered age, height, and weight as independent factors that may modify these parameters. The clinical data were divided into the study arm and validation group. The study arms were used to construct predictive equations using stepwise multiple linear regression, and data from the validation group were used to assess the robustness of the equations. Results: The 3866 participants were randomized into a study arm (n = 1,949) and a validation arm (n = 1,917). Lung function parameters had a negative association with age and a positive association with height. Data from the two groups were similar. Predictive equations were constructed from the study arm, and the validation group was used to test the feasibility of the reference equations. Conclusions: The reference values we derived can be used to evaluate lung function in this cohort in both epidemiological studies and clinical practice.

Benzo[a]pyrene inhibits myoblast differentiation through downregulating the Hsp70-MK2-p38MAPK complex.

Cigarette smoking causes skeletal muscle dysfunction and worse prognosis for patients with diverse systemic diseases. Benzo[a]pyrene (BaP), one major constituent that is inhaled during smoking, is particularly known for its ability to impair neurodevelopment, impede reproductivity, or reduce birth weight. Here, we found that BaP exposure led to the inhibition of C2C12 myoblasts differentiation in a dose-dependent manner and reduced the expression of both early and late myogenic differentiation markers. BaP exposure significantly decreased the expression of p38 mitogen-activated protein kinase (p38MAPK), but not AKT, which are both critical during myogenic differentiation. Mechanistically, BaP downregulated the expression levels of MAPK-activated protein kinase 2 (MK2) and heat shock protein 70 (Hsp70), both of which stabilize p38MAPK. Interestingly, treatment of proteasome inhibitor MG132 was able to reverse BaP-induced degradation of Hsp70/ MK2 and p38MAPK in myoblasts, implying BaP-mediated p38MAPK degradation is proteasome-dependent. Overexpression of p38MAPK also rescued the defective differentiation phenotype of C2C12 induced by BaP. Taken together, we suggest that BaP exposure induces MK2/Hsp70/p38MAPK complex degradation in C2C12 myoblasts and impairs myogenic differentiation by proteasomal-dependent mechanisms. As application of the proteasome inhibitor MG132 or overexpression of p38MAPK could reverse impaired differentiation of myoblasts induced by BaP, this may suggest potential related strategies for preventing tobacco-related skeletal muscle diseases or for respiratory rehabilitation.