Outcome of acute respiratory distress syndrome in university and non-university hospitals in Germany

Risk Factors for Death of Burn Patients With Acute Respiratory Distress Syndrome

The aim of this study was to investigate factors independently affecting outcomes of post-burn ARDS patients at the time of ARDS onset. A prospective study was conducted on 66 patients with ARDS, treated in the ICU at the Le Huu Trac National Burns Hospital in Hanoi, Viet Nam, from 2014 to 2017. Patients were divided into a survivor and non-survivor group. Demographic criteria, burn severity, inhalation injury, clinical and subclinical features at ARDS onset were compared between the two groups. The results showed that overall mortality of ARDS patients was 62.12%. Logistic regression analysis indicated that at the time of ARDS onset, serum lactate level (OR=6.71), blood platelet count (OR=.99), static lung compliance (OR=.73) and driving pressure (OR=1.69) were independent risk factors for death, while patients' demographics, burn severity and ARDS severity did not significantly affect the mortality rate.

Therapeutic Use of Cannabinoids in Critically Ill Patients: A Survey of Intensive Care Physicians in Germany

Background: In the course of the legalization of cannabis for therapeutic purposes in Germany, there has been growing interest in the medical use of cannabinoids. To date, the therapeutic potential of cannabinoids for the treatment of critically ill patients has not been explored. Objectives: This study aims to understand better whether and how frequently cannabinoids have been administered to critically ill patients in recent years. Study Design: Initially, a survey was conducted among physicians working in intensive care units (ICUs) at the Hannover Medical School. Subsequently, 653 physicians working in ICUs throughout Germany were surveyed. The frequency and regimen of cannabinoid therapy initiated by the participating physicians in the last 2 years at the time of the survey were characterized. Results: Eight out of 9 physicians at Hannover Medical School and 59 out of 653 physicians in ICUs in Germany participated. At Hannover Medical School, 6 out of 8 physicians and in ICUs in Germany, 16 out of 59 physicians had used cannabinoids in some patients (mainly 9-10) during the 2-year period studied, with dronabinol in doses between 1 and 20 mg being their cannabinoid of choice. Metabolic and psychological distress and medication savings, followed by pain and nausea/vomiting, were the most frequently cited indications for cannabinoid therapy. No relevant safety issues arrived. Lack of personal experience, limited evidence, and gaps in knowledge were the most commonly cited reservations about cannabinoid use. Conclusions: During a 2-year period, dronabinol is used in a few critically ill patients in ICUs. The main indications are to reduce metabolic and psychological distress and to save medication. The majority of participating physicians indicated that the use of cannabinoids in the context of critical care medicine needs further exploration.

1-year survival rate of SARS-CoV-2 infected patients with acute respiratory distress syndrome based on ventilator types: a multi-center study

The aim of this study was to evaluate the association between types of ventilator and the one-year survival rate of patients with acute respiratory distress syndrome (ARDS) due to SARS‑CoV-2 infection. This multi-center, retrospective observational study was conducted on 1078 adult patients admitted to five university-affiliated hospitals in Iran who underwent mechanical ventilator (MV) due to ARDS. Of the 1078 patients, 781 (72.4%) were managed with ICU ventilators and 297 (27.6%) with transport ventilators. Overall mortality was significantly higher in patients supported with transport ventilator compared to patients supported with ICU ventilator (16.5% vs. 9.3% P = 0.001). Regression analysis revealed that the expected hazard overall increased with age (HR: 1.525, 95% CI 1.112-1.938, P = 0.001), opacity score (HR: 1.448, 95% CI 1.122-2.074, P = 0.001) and transport ventilator versus ICU ventilator (HR: 1.511, 95% CI 1.143-2.187, P = 0.029). The Kaplan-Meier curves of survival analysis showed that patients supported with ICU ventilator had a significantly higher 1-year survival rate (P = 0.001). In MV patients with ARDS due to COVID-19, management with non-ICU sophisticated ventilators was associated with a higher mortality rate compared to standard ICU ventilators. However, more studies are needed to determine the exact effect of ventilator types on the outcome of critically ill patients.

Delivery of Lung-protective Ventilation for Acute Respiratory Distress Syndrome: A Hybrid Implementation-Effectiveness Trial

Rationale: Lung-protective ventilation (LPV) improves outcomes for patients with acute respiratory distress syndrome (ARDS), but adherence remains inadequate. Objectives: To measure the process and clinical impacts of implementation of a science-based intervention to improve LPV adherence for patients with ARDS, in part by increased use of clinical decision support (CDS). Methods: We conducted a type III hybrid implementation/effectiveness pilot trial enrolling adult patients with ARDS admitted to three hospitals before and after the launch of a multimodal implementation intervention to increase the use of mechanical ventilation CDS and improve LPV adherence. The primary outcome was patients' percentage of time adherent to low tidal volume (⩽6.5 ml/kg predicted body weight) ventilation (LTVV). Secondary outcomes included adherence to prescribed oxygenation settings, the use of the CDS tool's independent oxygenation and ventilation components, ventilator-free days, and mortality. Analyses employed multivariable regression to compare adjusted pre- versus postintervention outcomes after the exclusion of a postintervention wash-in period. A sensitivity analysis measured process outcomes' level and trend change postintervention using segmented regression. Results: The 446 included patients had a mean age of 60 years, and 43% were female. Demographic and clinical characteristics were similar pre- versus postintervention. The adjusted proportion of adherent time increased postintervention for LTVV (9.2%; 95% confidence interval [CI], 3.8-14.5%) and prescribed oxygenation settings (11.9%; 95% CI, 7.2-16.5%), as did the probability patients spent ⩾90% of ventilated time on LTVV (adjusted odds ratio [aOR] 2.58; 95% CI, 1.64-4.10) and use of ventilation CDS (aOR, 41.3%; 95% CI, 35.9-46.7%) and oxygenation CDS (aOR, 54.3%; 95% CI, 50.9-57.7%). Ventilator-free days (aOR, 1.15; 95% CI, 0.81-1.62) and 28-day mortality (aOR, 0.78; 95% CI, 0.50-1.20) did not change significantly after intervention. Segmented regression analysis supported a causal relationship between the intervention and improved CDS usage but suggested trends before intervention rather than the studied intervention could explain increased LPV adherence after the intervention. Conclusions: In this pilot trial, a multimodal implementation intervention was associated with increased use of ventilator management CDS for patients with ARDS but was not associated with differences in clinical outcomes and may not have independently caused the observed postintervention improvements in LPV adherence. Clinical trial registered with www.clinicaltrials.gov (NCT03984175).

Monitoring of Cerebral Oxygen Saturation in Interhospital Transport of Patients Receiving Extracorporeal Membrane Oxygenation

Extracorporeal membrane oxygenation (ECMO) in acute respiratory distress syndrome (ARDS) is used to achieve oxygenation and protect lung ventilation. Near infrared spectroscopy (NIRS) measures cerebral regional tissue oxygenation (rSO 2 ) and may contribute to patient safety during interhospital transport under ECMO support. We evaluated 16 adult ARDS patients undergoing interhospital ECMO transport by measuring cerebral rSO 2 before and after initiation of ECMO support and continuously during transport. To compare peripheral oxygen saturation (SpO 2 ) measurement with rSO 2 , both parameters were analyzed. NIRS monitoring for initiation of ECMO and interhospital transport under ECMO support was feasible, and there was no significant difference in the percentage of achievable valid measurements over time between cerebral rSO 2 (88.4% [95% confidence interval {CI}, 81.3-95.0%]) and standard SpO 2 monitoring 91.7% (95% CI, 86.1-94.2%), p = 0.68. No change in cerebral rSO 2 was observed before 77% (73.5-81%) (median [interquartile range {IQR}]) and after initiation of ECMO support 78% (75-81%), p = 0.2. NIRS for cerebral rSO 2 measurement is feasible during ECMO initiation and interhospital transport. Achievement of valid measurements of cerebral rSO 2 was not superior to SpO 2 . In distinct patients ( e.g. , shock), measurement of cerebral rSO 2 may contribute to improvement of patient safety during interhospital ECMO transport.

Samadi M, Polzin R, Mayer H, Marx G, Bickenbach J, Schuppert A. Application of convex hull analysis for the evaluation of data heterogeneity between patient populations of different origin and implications of hospital bias in downstream machine-learning-based data processing: A comparison of 4 critical-care patient datasets

Machine learning (ML) models are developed on a learning dataset covering only a small part of the data of interest. If model predictions are accurate for the learning dataset but fail for unseen data then generalization error is considered high. This problem manifests itself within all major sub-fields of ML but is especially relevant in medical applications. Clinical data structures, patient cohorts, and clinical protocols may be highly biased among hospitals such that sampling of representative learning datasets to learn ML models remains a challenge. As ML models exhibit poor predictive performance over data ranges sparsely or not covered by the learning dataset, in this study, we propose a novel method to assess their generalization capability among different hospitals based on the convex hull (CH) overlap between multivariate datasets. To reduce dimensionality effects, we used a two-step approach. First, CH analysis was applied to find mean CH coverage between each of the two datasets, resulting in an upper bound of the prediction range. Second, 4 types of ML models were trained to classify the origin of a dataset (i.e., from which hospital) and to estimate differences in datasets with respect to underlying distributions. To demonstrate the applicability of our method, we used 4 critical-care patient datasets from different hospitals in Germany and USA. We estimated the similarity of these populations and investigated whether ML models developed on one dataset can be reliably applied to another one. We show that the strongest drop in performance was associated with the poor intersection of convex hulls in the corresponding hospitals' datasets and with a high performance of ML methods for dataset discrimination. Hence, we suggest the application of our pipeline as a first tool to assess the transferability of trained models. We emphasize that datasets from different hospitals represent heterogeneous data sources, and the transfer from one database to another should be performed with utmost care to avoid implications during real-world applications of the developed models. Further research is needed to develop methods for the adaptation of ML models to new hospitals. In addition, more work should be aimed at the creation of gold-standard datasets that are large and diverse with data from varied application sites.

The PANDORA Study: Prevalence and Outcome of Acute Hypoxemic Respiratory Failure in the Pre-COVID-19 Era

OBJECTIVES:

To establish the epidemiological characteristics, ventilator management, and outcomes in patients with acute hypoxemic respiratory failure (AHRF), with or without acute respiratory distress syndrome (ARDS), in the era of lung-protective mechanical ventilation (MV).

DESIGN:

A 6-month prospective, epidemiological, observational study.

SETTING:

A network of 22 multidisciplinary ICUs in Spain.

PATIENTS:

Consecutive mechanically ventilated patients with AHRF (defined as Pao₂/Fio₂ ≤ 300 mm Hg on positive end-expiratory pressure [PEEP] ≥ 5 cm H₂O and Fio₂ ≥ 0.3) and followed-up until hospital discharge.

INTERVENTIONS:

None.

MEASUREMENTS AND MAIN RESULTS:

Primary outcomes were prevalence of AHRF and ICU mortality. Secondary outcomes included prevalence of ARDS, ventilatory management, and use of adjunctive therapies. During the study period, 9,803 patients were admitted: 4,456 (45.5%) received MV, 1,271 (13%) met AHRF criteria (1,241 were included into the study: 333 [26.8%] met Berlin ARDS criteria and 908 [73.2%] did not). At baseline, tidal volume was 6.9 ± 1.1 mL/kg predicted body weight, PEEP 8.4 ± 3.1 cm H₂O, Fio₂ 0.63 ± 0.22, and plateau pressure 21.5 ± 5.4 cm H₂O. ARDS patients received higher Fio₂ and PEEP than non-ARDS (0.75 ± 0.22 vs 0.59 ± 0.20 cm H₂O and 10.3 ± 3.4 vs 7.7 ± 2.6 cm H₂O, respectively [p < 0.0001]). Adjunctive therapies were rarely used in non-ARDS patients. Patients without ARDS had higher ventilator-free days than ARDS (12.2 ± 11.6 vs 9.3 ± 9.7 d; p < 0.001). All-cause ICU mortality was similar in AHRF with or without ARDS (34.8% [95% CI, 29.7–40.2] vs 35.5% [95% CI, 32.3–38.7]; p = 0.837).

CONCLUSIONS:

AHRF without ARDS is a very common syndrome in the ICU with a high mortality that requires specific studies into its epidemiology and ventilatory management. We found that the prevalence of ARDS was much lower than reported in recent observational studies.

Improving the quality of the performance and delivery of continuous renal replacement therapy (CRRT) to critically ill patients across a healthcare system: QUALITY CRRT: a study protocol

INTRODUCTION

Continuous renal replacement therapy (CRRT) is a continuous form of dialysis used to support critically ill patients with acute kidney injury. The ideal delivery of CRRT requires ongoing monitoring and reporting to adjust practice and deliver optimal therapy. However, this practice occurs variably.

METHODS

QUALITY CRRT is a multicentre, prospective, stepped-wedged, interrupted time series (ITS) evaluation of the effectiveness, safety and cost of implementing a multifaceted CRRT quality assurance and improvement programme across an entire healthcare system. This study will focus on the standardisation of CRRT programmes with similar structure, process and outcome metrics by the reporting of CRRT key performance indicators (KPIs). The primary outcome will be the quarterly performance of CRRT KPIs. Secondary outcomes will include patient-centred outcomes and economic outcomes. Analysis will compare pre-implementation and post-implementation groups as well as for the performance of KPIs using an ITS methodology. The health economic evaluation will include a within-study analysis and a longer-term model-based analysis.

DISCUSSION

The effective delivery of CRRT to critically ill patients ideally requires a standardised approach of best practice assessment and ongoing audit and feedback of standardised performance measures. QUALITY CRRT will test the application of this strategy stakeholder engagement and stepped-wedged implementation across an entire healthcare system.

ETHICS AND DISSEMINATION

This study has received ethics approval. We will plan to publish the results in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

NCT04221932.

PROTOCOL VERSION

1.0 (15 June 2020).

Intensive Care Resources and 60-Day Survival of Critically-Ill COVID-19 Patients

BACKGROUND

Germany reported sufficient intensive care unit (ICU) resources throughout the first wave of coronavirus disease 2019 (COVID-19). The treatment of critically ill COVID-19 patients without rationing may improve the outcome. We therefore analyzed ICU resources allocated to COVID-19 patients with respiratory failure and their outcomes.

METHODS

Retrospectively, we enrolled severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) polymerase chain reaction (PCR)-positive patients with respiratory failure from 03/08/2020 to 04/08/2020 and followed until 05/28/2020 in the university hospital of Freiburg, Germany.

RESULTS

In the defined interval, 34 COVID-19 patients were admitted to the ICU with median age of 67±13 (31-86) years. Six of 34 (17.6%) were female. All patients suffered from moderate or severe acute respiratory distress syndrome (ARDS), 91.2% of the patients were intubated and 23.5% required extracorporeal membrane oxygenation (ECMO). Proning was performed in 67.6%, renal replacement therapy (RRT) was required in 35.3%. Ninety-six percent required more than 20 nursing hours per day. Mean ICU stay was 21±19 (1-81) days. Sixty-day survival of critically ill COVID-19 patients was 50.0% (17/34). Causes of death were multi-organ failure (52.9%), refractory ARDS (17.6%) and intracerebral hemorrhage (17.6%).

CONCLUSIONS

Treatment of critically ill COVID-19 patients is protracted and resource-intense. In a context without resources shortage, 50% of COVID-19 with respiratory failure survived up to 60 days.

University Teaching Trauma Centers: Decreased Mortality but Increased Complications

BACKGROUND

Teaching hospitals are often regarded as excellent institutions with significant resources and prominent academic faculty. However, the involvement of trainees may contribute to higher rates of complications. Conflicting reports exist regarding outcomes between teaching and nonteaching hospitals, and the difference among trauma centers is unknown. We hypothesized that university teaching trauma centers (UTTCs) and nonteaching trauma centers (NTTCs) would have a similar risk of complications and mortality.

METHODS

We queried the Trauma Quality Improvement Program (2010-2016) for adults treated at UTTCs or NTTCs. A multivariable logistic regression analysis was performed to evaluate the risk of mortality and in-hospital complications, such as respiratory complications (RCs), venous thromboembolisms (VTEs), and infectious complications (ICs).

RESULTS

From 895,896 patients, 765,802 (85%) were treated at UTTCs and 130,094 (15%) at NTTCs. After adjusting for covariates, UTTCs were associated with an increased risk of RCs (odds ratio (OR) 1.33, confidence interval (CI) 1.28-1.37, P < 0.001), VTEs (OR 1.17, CI 1.12-1.23, P < 0.001), and ICs (OR 1.56, CI 1.49-1.64, P < 0.001). However, UTTCs were associated with decreased mortality (OR 0.96, CI 0.93-0.99, P = 0.008) compared with NTTCs.

CONCLUSIONS

Our study demonstrates increased associated risks of RCs, VTEs, and ICs, yet a decreased associated risk of in-hospital mortality for UTTCs when compared with NTTCs. Future studies are needed to identify the underlying causative factors behind these differences.

[Health services research in intensive care medicine in Germany : Status quo and future challenges exemplified by acute pulmonary failure]

Health services research (HSR) is a multidisciplinary field of research that describes disease treatment and health care and their framework conditions. In the last 20 years, the HSR aspect became more and more the clinical focus of intensive care medicine. Under this aspect HSR investigates the use of clinical measures and their impact on patient outcome under routine intensive care medical conditions. This article provides an overview of the current state of HSR in intensive care medicine in Germany using the example of acute respiratory distress syndrome (ARDS). The ARDS still represents a clinical disease with high intra-hospital mortality (30-60%) despite progress in intensive care medicine. Survivors of ARDS have substantial long-term limitations on physical and mental health. The treatment of ARDS patients is tedious, laborious for intensive care unit staff and complex. Despite evident treatment recommendations, these are only insufficiently implemented in the clinical routine. With the help of quality indicators, benchmarking, certification and peer review procedures, the quality of intensive care treatment in the clinical routine can be documented and improved. An important role in HSR is patient safety and focusing on the outcome with evaluation of the patient's will. As part of the establishment of the innovation fund for HSR, promising intensive medical care projects have been promoted to improve the quality of care and the quality of long-term outcome for intensive care patients. An important focus lies on the identification of factors that improve long-term quality of life after intensive care. The expansion of registries and telemedicine in intensive care offers the opportunity to bundle and share experiences more effectively and thereby establish (guideline-based) treatment recommendations faster in the clinical practice.

Influence of quality of intensive care on quality of life/return to work in survivors of the acute respiratory distress syndrome: prospective observational patient cohort study (DACAPO)

Background

Significant long-term reduction in health-related quality of life (HRQoL) is often observed in survivors of the acute respiratory distress syndrome (ARDS), and return to work (RtW) is limited. There is a paucity of data regarding the relationship between the quality of care (QoC) in the intensive care unit (ICU) and both HRQoL and RtW in ARDS survivors. Therefore, the aim of our study was to investigate associations between indicators of QoC and HRQoL and RtW in a cohort of survivors of ARDS.

Methods

To determine the influence of QoC on HRQoL and RtW 1 year after ICU-discharge, ARDS patients were recruited into a prospective multi-centre patient cohort study and followed up regularly after discharge. Patients were asked to complete self-report questionnaires on HRQoL (Short Form 12 physical component scale (PCS) and mental component scale (MCS)) and RtW. Indicators of QoC pertaining to volume, structural and process quality, and general characteristics were recorded on ICU level. Associations between QoC indicators and HrQoL and RtW were investigated by multivariable linear and Cox regression modelling, respectively. B values and hazard ratios (HRs) are reported with corresponding 95% confidence intervals (CIs).

Results

877 (of initially 1225 enrolled) people with ARDS formed the DACAPO survivor cohort, 396 were finally followed up to 1 year after discharge. The twelve-month survivors were characterized by a reduced HRQoL with a greater impairment in the physical component (Md 41.2 IQR [34–52]) compared to the mental component (Md 47.3 IQR [33–57]). Overall, 50% of the patients returned to work. The proportion of ventilated ICU patients showed significant negative associations with both 12 months PCS (B = − 11.22, CI −20.71; − 1,74) and RtW (HR = 0,18, CI 0,04;0,80). All other QoC indicators were not significantly related to outcome.

Conclusions

Associations between ICU QoC and long-term HrQoL and RtW were weak and largely non-significant. Residual confounding by case mix, treatment variables before or during ICU stay and variables pertaining to the post intensive care period (e.g. rehabilitation) cannot be ruled out.

Trial registration

Clinicaltrials.govNCT02637011.

(December 22, 2015, retrospectively registered)

A Physiologically Informed Strategy to Effectively Open, Stabilize, and Protect the Acutely Injured Lung

Acute respiratory distress syndrome (ARDS) causes a heterogeneous lung injury and remains a serious medical problem, with one of the only treatments being supportive care in the form of mechanical ventilation. It is very difficult, however, to mechanically ventilate the heterogeneously damaged lung without causing secondary ventilator-induced lung injury (VILI). The acutely injured lung becomes time and pressure dependent, meaning that it takes more time and pressure to open the lung, and it recollapses more quickly and at higher pressure. Current protective ventilation strategies, ARDSnet low tidal volume (LVt) and the open lung approach (OLA), have been unsuccessful at further reducing ARDS mortality. We postulate that this is because the LVt strategy is constrained to ventilating a lung with a heterogeneous mix of normal and focalized injured tissue, and the OLA, although designed to fully open and stabilize the lung, is often unsuccessful at doing so. In this review we analyzed the pathophysiology of ARDS that renders the lung susceptible to VILI. We also analyzed the alterations in alveolar and alveolar duct mechanics that occur in the acutely injured lung and discussed how these alterations are a key mechanism driving VILI. Our analysis suggests that the time component of each mechanical breath, at both inspiration and expiration, is critical to normalize alveolar mechanics and protect the lung from VILI. Animal studies and a meta-analysis have suggested that the time-controlled adaptive ventilation (TCAV) method, using the airway pressure release ventilation mode, eliminates the constraints of ventilating a lung with heterogeneous injury, since it is highly effective at opening and stabilizing the time- and pressure-dependent lung. In animal studies it has been shown that by “casting open” the acutely injured lung with TCAV we can (1) reestablish normal expiratory lung volume as assessed by direct observation of subpleural alveoli; (2) return normal parenchymal microanatomical structural support, known as alveolar interdependence and parenchymal tethering, as assessed by morphometric analysis of lung histology; (3) facilitate regeneration of normal surfactant function measured as increases in surfactant proteins A and B; and (4) significantly increase lung compliance, which reduces the pathologic impact of driving pressure and mechanical power at any given tidal volume.

Prevention and treatment of acute lung injury with time-controlled adaptive ventilation: physiologically informed modification of airway pressure release ventilation

Mortality in acute respiratory distress syndrome (ARDS) remains unacceptably high at approximately 39%. One of the only treatments is supportive: mechanical ventilation. However, improperly set mechanical ventilation can further increase the risk of death in patients with ARDS. Recent studies suggest that ventilation-induced lung injury (VILI) is caused by exaggerated regional lung strain, particularly in areas of alveolar instability subject to tidal recruitment/derecruitment and stress-multiplication. Thus, it is reasonable to expect that if a ventilation strategy can maintain stable lung inflation and homogeneity, regional dynamic strain would be reduced and VILI attenuated. A time-controlled adaptive ventilation (TCAV) method was developed to minimize dynamic alveolar strain by adjusting the delivered breath according to the mechanical characteristics of the lung. The goal of this review is to describe how the TCAV method impacts pathophysiology and protects lungs with, or at high risk of, acute lung injury. We present work from our group and others that identifies novel mechanisms of VILI in the alveolar microenvironment and demonstrates that the TCAV method can reduce VILI in translational animal ARDS models and mortality in surgical/trauma patients. Our TCAV method utilizes the airway pressure release ventilation (APRV) mode and is based on opening and collapsing time constants, which reflect the viscoelastic properties of the terminal airspaces. Time-controlled adaptive ventilation uses inspiratory and expiratory time to (1) gradually “nudge” alveoli and alveolar ducts open with an extended inspiratory duration and (2) prevent alveolar collapse using a brief (sub-second) expiratory duration that does not allow time for alveolar collapse. The new paradigm in TCAV is configuring each breath guided by the previous one, which achieves real-time titration of ventilator settings and minimizes instability induced tissue damage. This novel methodology changes the current approach to mechanical ventilation, from arbitrary to personalized and adaptive. The outcome of this approach is an open and stable lung with reduced regional strain and greater lung protection.

Risk Factors and Etiologies of Pediatric Acute Respiratory Distress Syndrome

The risk factors for acute respiratory distress syndrome (ARDS) have been a focus for clinicians and researchers from the original description in 1967 to the most recent Pediatric Acute Lung Injury Consensus Conference (PALICC). Indeed, there are many comorbidities and risk factors that predispose a patient to develop pediatric ARDS (PARDS) including, but not limited to, immunodeficiency, weight extremes, genetics, and environmental factors. These are particularly important to investigators because accurate prediction of which patients are at greatest risk of PARDS – both the development of PARDS and worse clinical outcomes after PARDS has been established – is key to identifying the next generation of diagnostic techniques and preventative strategies. In addition to those risk factors, there are specific disease processes that lead to the development of PARDS, often divided into direct or pulmonary insults and indirect or extrapulmonary insults. Finally, beyond the clinically visible risk factors, researchers are attempting to identify novel biomarkers to uncover hidden phenotypes of PARDS and enrich the prognostication and prediction of patient outcomes. This chapter delves into each of these concepts.

Smoking Attenuates Efficacy of Penehyclidine Hydrochloride in Acute Respiratory Distress Syndrome Induced by Lipopolysaccharide in Rats

Background

Penehyclidine hydrochloride is a novel drug for acute respiratory distress syndrome. The aim of the study was to reveal the impact of smoking on the efficacy of the drug in rats with acute respiratory distress syndrome.

Material/Methods

A 132 Sprague-Dawley rats were used in this study; 72 rats were used in the smoking models. Penehyclidine hydrochloride (3 mg/kg) was injected to induce acute respiratory distress syndrome. Rats were divided into the smoking group and the non-smoking group; these 2 groups were subdivided according to different treatments. The arterial blood gas analysis (PaO₂/FiO₂) and extent of pneumonedema (wet-to-dry weight ratio) was analyzed to evaluate disease severity. Expressions of mitogen-activated protein kinases (p-p38MAPK, p38MAPK, p-ERK, ERK, p-JNK, and JNK) in lung tissue were measured using western blot assay.

Results

Penehyclidine hydrochloride improved the pneumonedema (wet-to-dry weight ratio) and hyoxemia (PaO₂/FiO₂) of the disease in non-smoking group (P<0.001, P<0.001 respectively), but not in smoking group (P=0.244, P=0.424 respectively). The drug inhibited the expressions of phospho-p38MAPK and phospho-ERK in non-smoking group (P<0.001, P<0.001 respectively), but not in smoking group (P=0.350, P=0.507 respectively). In the smoking group, blocking the phospho-p38MAPK or phospho-ERK signal pathway by their inhibitors showed a better therapeutic effect on the pneumonedema and hyoxemia compared with the use of penehyclidine hydrochloride (phospho-p38MAPK: P=0.004, P=0.010 respectively; phospho-ERK: P=0.022, P=0.004 respectively).

Conclusions

The study confirmed the protective effect of penehyclidine hydrochloride in acute respiratory distress syndrome, mainly in the non-smoking group, which might be explained by the fact that phospho-p38MAPK and phospho-ERK signal pathways were difficult to inhibit by the drug in the smoking group.

Mechanical Ventilation and Extracorporeal Membrane Oxygena tion in Acute Respiratory Insufficiency

BACKGROUND

Mechanical ventilation is life-saving for patients with acute respiratory insufficiency. In a German prevalence study, 13.6% of patients in intensive care units received mechanical ventilation for more than 12 hours; 20% of these patients received mechanical ventilation as treatment for acute respiratory distress syndrome (ARDS). The new S3 guideline is the first to contain recommendations for the entire process of treatment in these groups of patients (indications, ventilation modes/parameters, ac- companying measures, treatments for refractory impairment of gas exchange, weaning, and follow-up care).

METHODS

This guideline was developed according to the GRADE methods. Pertinent publications were identified by a systematic search of the literature, the quality of the evidence was evaluated, a risk/benefit assessment was conducted, and recommendations were issued by interdisciplinary consensus.

RESULTS

Mechanical ventilation is recommended as primary treatment for patients with severe ARDS. In other patient groups, non-in- vasive ventilation can lower mortality. If mechanical ventilation is needed, ventilation modes allowing spontaneous breathing seem beneficial (quality of evidence [QoE]: very low). Protective ventilation (high positive end-expiratory pressure, low tidal volume, limited peak pressure) improve the survival of ARDS patients (QoE: high). If a severe impairment of gas exchange is present, prone posi- tioning lessens mortality (QoE: high). Veno-venous extracorporeal membrane oxygenation (vvECMO) has not unequivocally been shown to improve survival. Early mobilization and weaning protocols can shorten the duration of ventilation (QoE: moderate).

CONCLUSION

Recommendations for patients undergoing mechanical ventilation include lung-protective ventilation, early sponta- neous breathing and mobilization, weaning protocols, and, for those with severe impairment of gas exchange, prone positioning. It is further recommended that patients with ARDS and refractory impairment of gas exchange should be transferred to an ARDS/ECMO center, where extracorporeal methods should be applied only after application of all other therapeutic options.

Higher vs. Lower DP for Ventilated Patients with Acute Respiratory Distress Syndrome: A Systematic Review and Meta-Analysis

Objectives

Driving pressure (DP) has recently become a promising mediator for the identification of the effects of mechanical ventilation on outcomes in acute respiratory distress syndrome (ARDS). The aim of this study was to systematically and quantitatively update and assess the association between DP and mortality among ventilated patients with ARDS.

Methods

PubMed, the Cochrane Library, ISI Web of Knowledge, and Embase were systematically searched from inception to June 2018. Two investigators conducted the literature search study selection, data extraction, and quality evaluation independently. RevMan 5.3 software was used for all statistical analyses.

Results

A total of seven studies comprising 8010 patients were included in this meta-analysis. Higher DP showed a significant association with higher mortality (pooled risk ratio, 1.10; 95% [CI], 1.05–1.16; I² =58%). Sensitivity analysis indicated that one study significantly affected the stability of pooled results. One of the subgroups investigated, ARDS severity, could account for the heterogeneity. An exploratory post hoc subgroup analysis and higher DP significantly increased mortality in the mild to severe ARDS subgroup (RR 1.28; 95% [CI], 1.14–1.43; I² =0), but not in the moderate to severe ARDS subgroup (RR 1.18; 95% [CI], 0.95–1.46;  I² =52%).

Conclusion

Higher DP was significantly associated with an increased risk of death among ventilated patients with ARDS. But it did not seem to predict prognosis to moderate to severe ARDS. Future prospective randomized clinical trials are needed to verify the results of this meta-analysis and address the unresolved questions about optimum cutoff values for DP.

Trial Registration

This trial is registered with PROSPERO (CRD42018102146), on 11 August 2018.

Risk factors for outcomes of acute respiratory distress syndrome patients: a retrospective study

Background

The determination of risk factors for acute respiratory distress syndrome (ARDS) patients remains a challenge. Our study aims to explore the epidemiology and risk factors affecting outcomes of ARDS patients and provide a theoretical basis for patients' prognosis.

Methods

This retrospective study included 207 ARDS patients admitted to the general intensive care unit (ICU) in the Second Affiliated Hospital of Harbin Medical University from Jan 1st, 2016 to Jan 1st, 2017. The criteria were defined according to the Berlin Definition, and clinical data were collected from the medical record system. The mortality rate and duration of mechanical ventilation were compared in ARDS patients. Furthermore, logistic regression analysis was applied to screen clinically accessible risk factors for survival and duration of mechanical ventilation.

Results

The total mortality in ARDS patients was 39.13% (81/207) compared to 13.57% (151/1,113) in the whole ICU population. The period prevalence of mild, moderate and severe ARDS was 39.61% (82/207), 37.20% (77/207) and 23.19% (48/207), respectively. Logistic regression analysis showed that acute physiology and chronic health evaluation II (APACHE II) score (OR 3.4316; 95% CI: 1.3130-8.9686; P=0.0119), number of organ failure (OR 3.4928; 95% CI: 1.9775-6.1693; P<0.0001), mean arterial pressure (MAP) (OR 5.1049; 95% CI: 1.8317-14.2274; P=0.0018), driving pressure (OR 6.0017; 95% CI: 2.1746-16.5641; P=0.0005) and lactate level (OR 4.0754; 95% CI: 1.6114-10.3068; P=0.0030) were influence factors for survival; severity of ARDS (OR 1.6715; 95% CI: 1.0307-2.7108; P=0.0373), ventilator-associated pneumonia (VAP) (OR 7.3746; 95% CI: 2.9799-18.2505; P<0.0001) and transfusion history (OR 2.2822; 95% CI: 1.0462-4.9783; P=0.0381) were influence factors for duration of mechanical ventilation.

Conclusions

Higher APACHE II score, more organ failures, lower MAP, higher driving pressure and higher lactate level are risk factors for survival. Higher severity of ARDS, VAP and transfusion history are risk factors for prolonged duration of mechanical ventilation. Application of these parameters would enable intensivists to treat their patients more precisely and comprehensively.

Lessons to learn from epidemiologic studies in ARDS

PURPOSE OF REVIEW

Recent advances in our understanding of the epidemiology of ARDS has generated key insights into the incidence, risk factors, demographics, management and outcomes from this devastating clinical syndrome.

RECENT FINDINGS

ARDS occurs in 10% of all ICU patients, in 23% of all mechanically ventilated patients, with 5.5 cases per ICU bed each year. Although some regional variation exists regarding ARDS incidence, this may be less than previously thought. Subphenotypes are increasingly identified within the ARDS cohort, with studies identifying a 'hyperinflammatory' or 'reactive' subgroup that has a higher mortality, and may respond differently to therapeutic interventions. Demographic factors, such as race, may also affect the therapeutic response. Although mortality in ARDS is decreasing in clinical trials, it remains unchanged at approximately 40% in major observational studies. Modifiable ventilatory management factors, including PEEP, airway pressures, and respiratory rate are associated with mortality in ARDS. Hospital and ICU organizational factors play a role in outcome, whereas socioeconomic status is independently associated with survival in patients with ARDS. The Kigali adaptation of the Berlin ARDS definition may provide useful insights into the burden of ARDS in the developing world.

SUMMARY

ARDS exerts a substantial disease burden, with 40% of patients dying in hospital. Diverse factors, including patient-related factors such as age and illness severity, country level socioeconomic status, and ventilator management and ICU organizational factors each contribute to outcome from ARDS. Addressing these issues provides opportunities to improve outcome in patients with ARDS.

Low endocan levels are predictive of Acute Respiratory Distress Syndrome in severe sepsis and septic shock

PURPOSE

Endocan is a circulating proteoglycan measured at high blood levels during severe sepsis, with a likely lung anti-inflammatory function. The aim of this study was to assess whether paradoxically low endocan levels at Intensive Care Unit (ICU) admission could predict Acute Respiratory Distress Syndrome (ARDS) within 72 h in severe septic patients.

MATERIALS AND METHODS

Patients admitted for severe sepsis in the ICU of a French University Hospital were included in a prospective single-center observational study between October 2014 and March 2016.

RESULTS

72 patients admitted in ICU for severe sepsis were included. Endocan blood values at inclusion were significantly lower in patients who developed an ARDS at 72 h (p < 0.001). For endocan blood values > 5.36 ng/mL, the adjusted OR for development of ARDS at 72 h was of 0.001 (95% CI 0-0.215; p = 0.011). In our cohort, an endocan value < 2.54 ng/mL predicted ARDS at 72 h with a positive predictive value of 1 (Sp = 1 (95% CI 0.94-1)).

CONCLUSIONS

In a cohort of severe septic patients, we observed that low blood levels of endocan at ICU admission were predictive of ARDS at 72 h.

Quality of inter-hospital transportation in 431 transport survivor patients suffering from acute respiratory distress syndrome referred to specialist centers

Background

The acute respiratory distress syndrome (ARDS) is a life-threatening condition. In special situations, these critically ill patients must be transferred to specialized centers for escalating treatment. The aim of this study was to evaluate the quality of inter-hospital transport (IHT) of ARDS patients.

Methods

We evaluated medical and organizational aspects of structural and procedural quality relating to IHT of patients with ARDS in a prospective nationwide ARDS study. The qualification of emergency staff, the organizational aspects and the occurrence of critical events during transport were analyzed.

Results

Out of 1234 ARDS patients, 431 (34.9%) were transported, and 52 of these (12.1%) treated with extracorporeal membrane oxygenation. 63.1% of transferred patients were male, median age was 54 years, and 26.8% of patients were obese. All patients were mechanically ventilated during IHT. Pressure-controlled ventilation was the preferred mode (92.1%). Median duration to organize the IHT was 165 min. Median distance for IHT was 58 km, and median duration of IHT 60 min. Forty-two patient-related and 8 technology-related critical events (11.6%, 50 of 431 patients) were observed. When a critical event occurred, the PaO₂/FiO₂ ratio before transport was significant lower (68 vs. 80 mmHg, p = 0.017). 69.8% of physicians and 86.7% of paramedics confirmed all transfer qualifications according to requirements of the German faculty guidelines (DIVI).

Conclusions

The transport of critically ill patients is associated with potential risks. In our study the rate of patient- and technology-related critical events was relatively low. A severe ARDS with a PaO₂/FiO₂ ratio < 70 mmHg seems to be a risk factor for the appearance of critical events during IHT. The majority of transport staff was well qualified. Time span for organization of IHT was relatively short. ECMO is an option to transport patients with a severe ARDS safely to specialized centers.

Trial registration NCT02637011 (ClinicalTrials.gov, Registered 15 December 2015, retrospectively registered)