The role of potentially preventable hospital exposures in the development of acute respiratory distress syndrome: a population-based study

A scoring model based on clinical factors to predict postoperative moderate to severe acute respiratory distress syndrome in Stanford type A aortic dissection

BACKGROUND

Postoperative acute respiratory distress syndrome (ARDS) after type A aortic dissection is common and has high mortality. However, it is not clear which patients are at high risk of ARDS and an early prediction model is deficient.

METHODS

From May 2015 to December 2017, 594 acute Stanford type A aortic dissection (ATAAD) patients who underwent aortic surgery in Anzhen Hospital were enrolled in our study. We compared the early survival of MS-ARDS within 24 h by Kaplan-Meier curves and log-rank tests. The data were divided into a training set and a test set at a ratio of 7:3. We established two prediction models and tested their efficiency.

RESULTS

The oxygenation index decreased significantly immediately and 24 h after TAAD surgery. A total of 363 patients (61.1%) suffered from moderate and severe hypoxemia within 4 h, and 243 patients (40.9%) suffered from MS-ARDS within 24 h after surgery. Patients with MS-ARDS had higher 30-day mortality than others (log-rank test: p-value <0.001). There were 30 variables associated with MS-ARDS after surgery. The XGboost model consisted of 30 variables. The logistic regression model (LRM) consisted of 11 variables. The mean accuracy of the XGBoost model was 70.7%, and that of the LRM was 80.0%. The AUCs of XGBoost and LRM were 0.764 and 0.797, respectively.

CONCLUSION

Postoperative MS-ARDS significantly increased early mortality after TAAD surgery. The LRM model has higher accuracy, and the XGBoost model has higher specificity.

Utilization of Continuous Positive Airway Pressure (CPAP) by Emergency Medical Services: Updated Systematic Review and Meta-analysis

BACKGROUND

While new studies are being published on the prehospital continuous positive airway pressure (CPAP) application in patients with respiratory failure with conflicting results, previous meta-analyses are showing the benefits of CPAP in the prehospital transfer of patients with respiratory distress. Before the clinical application of high-level evidence, updated pooled estimates are needed based on the growing literature. This study aimed to compare prehospital CPAP with the usual standard oxygen therapy of respiratory failure patients.

MATERIALS AND METHODS

PRISMA guidelines served as the framework for this updated review study. It is an extension of a prior systematic review. We conducted comprehensive searches across several databases, including PubMed, Web of Science, Embase, and Scopus, focusing on randomized trials that juxtaposed pre-hospital CPAP application against standard care. Our primary interest was to assess the in-hospital mortality risks, and we employed random effect models to aggregate risk ratios from the selected studies.

RESULTS

Four articles were gathered based on the review of the updated literature (2013 to November 2022) in conjunction with the research incorporated in the preceding meta-analysis with a total number of 747 patients receiving prehospital CPAP with 101 events of in-hospital mortality. In the standard treatment control groups, there were 713 patients and 115 deaths occurred. Pooled mortality risk comparison between the group of prehospital CPAP and standard care patients had no statistically significant difference (P=0.16). There was no heterogenicity. A regression between the year of the studies and the effect size showed increased RR in new studies (P=0.017).

CONCLUSION

Still more randomized trials are needed with higher sample sizes to conclude the lifesaving efficacy of the out-of-hospital CPAP.

Rab26 promotes macrophage phagocytosis through regulation of MFN2 trafficking to mitochondria

Acute respiratory distress syndrome (ARDS) is an inflammatory disorder of the lungs caused by bacterial or viral infection. Timely phagocytosis and clearance of pathogens by macrophages are important in controlling inflammation and alleviating ARDS. However, the precise mechanism of macrophage phagocytosis remains to be explored. Here, we show that the expression of Rab26 is increased in Escherichia coli- or Pseudomonas aeruginosa-stimulated bone marrow-derived macrophages. Knocking out Rab26 reduced phagocytosis and bacterial clearance by macrophages. Rab26 interacts with mitochondrial fusion protein mitofusin-2 (MFN2) and affects mitochondrial reactive oxygen species generation by regulating MFN2 transport. The levels of MFN2 in mitochondria were reduced in Rab26-deficient bone marrow-derived macrophages, and the levels of mitochondrial reactive oxygen species and ATP were significantly decreased. Knocking down MFN2 using small interfering RNA resulted in decreased phagocytosis and killing ability of macrophages. Rab26 knockout reduced phagocytosis and bacterial clearance by macrophages in vivo, significantly increased inflammatory factors, aggravated lung tissue damage, and increased mortality in mice. Our results demonstrate that Rab26 regulates phagocytosis and clearance of bacteria by mediating the transport of MFN2 to mitochondria in macrophages, thus alleviating ARDS in mice and potentially in humans.

Respiratory Distress Complicating Falciparum Malaria Imported to Berlin, Germany: Incidence, Burden, and Risk Factors

While European healthcare systems face resource shortages as a consequence of the coronavirus pandemic, numbers of imported falciparum malaria cases increased again with re-intensifying international travel. The aim of the study was to identify malaria-specific complications associated with a prolonged intensive care unit (ICU) length of stay (ICU-LOS) in the pre-COVID-19 era and to determine targets for their prevention. This retrospective observational investigation included all the cases treated from 2001 to 2015 at the Charité University Hospital, Berlin. The association of malaria-specific complications with the ICU-LOS was assessed using a multivariate Cox proportional hazard regression. The risk factors for the individual complications were determined using a multivariate Bayesian logistic regression. Among the 536 included cases, 68 (12.7%) required intensive care and 55 (10.3%) suffered from severe malaria (SM). The median ICU-LOS was 61 h (IQR 38-91 h). Respiratory distress, which occurred in 11 individuals (2.1% of the total cases, 16.2% of the ICU patients, and 20% of the SM cases), was the only complication independently associated with ICU-LOS (adjusted hazard ratio for ICU discharge by 61 h 0.24, 95% confidence interval, 95%CI, 0.08-0.75). Shock (adjusted odds ratio, aOR, 11.5; 95%CI, 1.5-113.3), co-infections (aOR 7.5, 95%CI 1.2-62.8), and each mL/kg/h fluid intake in the first 24 treatment hours (aOR 2.2, 95%CI 1.1-5.1) were the independent risk factors for its development. Respiratory distress is not rare in severe imported falciparum malaria, and it is associated with a substantial burden. Cautious fluid management, including in shocked individuals, and the control of co-infections may help prevent its development and thereby reduce the ICU-LOS.

Developing and evaluating a machine-learning-based algorithm to predict the incidence and severity of ARDS with continuous non-invasive parameters from ordinary monitors and ventilators

OBJECTIVES

Major observational studies report that the mortality rate of acute respiratory distress syndrome (ARDS) is close to 40%. Different treatment strategies are required for each patient, according to the degree of ARDS. Early prediction of ARDS is helpful to implement targeted drug therapy and mechanical ventilation strategies for patients with different degrees of potential ARDS. In this paper, a new dynamic prediction machine learning model for ARDS incidence and severity is established and evaluated based on 28 parameters from ordinary monitors and ventilators, capable of dynamic prediction of the incidence and severity of ARDS. This new method is expected to meet the clinical practice requirements of user-friendliness and timeliness for wider application.

METHODS

A total of 4738 hospitalized patients who required ICU care from 159 hospitals are employed in this study. The models are trained by standardized data from electronic medical records. There are 28 structured, continuous non-invasive parameters that are recorded every hour. Seven machine learning models using only continuous, non-invasive parameters are developed for dynamic prediction and compared with methods trained by complete parameters and the traditional risk adjustment method (i.e., oxygenation saturation index method).

RESULTS

The optimal prediction performance (area under the curve) of the ARDS incidence and severity prediction models built using continuous noninvasive parameters reached0.8691 and 0.7765, respectively. In terms of mild and severe ARDS prediction, the AUC values are both above 0.85. The performance of the model using only continuous non-invasive parameters have an AUC of 0.0133 lower, in comparison with that employing a complete feature set, including continuous non-invasive parameters, demographic information, laboratory parameters and clinical natural language text.

CONCLUSIONS

A machine learning method was developed in this study using only continuous non-invasive parameters for ARDS incidence and severity prediction. Because the continuous non-invasive parameters can be easily obtained from ordinary monitors and ventilators, the method presented in this study is friendly and convenient to use. It is expected to be applied in pre-hospital setting for early ARDS warning.

Post-Transplant and In-Hospital Risk Factors for ARDS After Hematopoietic Stem Cell Transplantation

BACKGROUND

ARDS is a serious complication of hematopoietic stem cell transplant (HSCT). Pre-transplant risk factors for developing ARDS after HSCT have been recently identified. The objective of this study was to better understand post-transplant risk factors for developing ARDS after HSCT.

METHODS

This was a nested case-control study. ARDS cases were matched to hospitalized non-ARDS controls by age, type of transplantation (allogeneic vs autologous), and time from transplantation. In a conditional logistic regression model, any potential risk factors were adjusted a priori for risk factors known to be associated with ARDS development.

RESULTS

One hundred and seventy ARDS cases were matched 1:1 to non-ARDS hospitalized controls. Pre-admission, cases were more likely to be on steroids (odds ratio [OR] 1.90 [1.13-3.19], P = .02). At time of admission, cases had lower platelet count (OR 0.95 [0.91-0.99], P = .02), lower bicarbonate (OR 0.94 [0.88-0.99], P = .035), and higher creatinine (OR 1.91 [1.23-2.94], P = .004). During the first 24 h after admission, cases were more likely to have received transfusion (OR 2.41 [1.48-3.94], P < .001), opioids (OR 2.94 [1.67-5.18], P < .001), and have greater fluid administration (OR 1.52 [1.30-1.78], P < .001). During the hospitalization, ARDS cases had higher temperature (OR 1.77 [1.34-2.33], P < .001) and higher breathing frequency (OR 1.52 [1.33-1.74], P < .001). ARDS cases were more likely to have had sepsis (OR 68.0 [15.2-301.7], P < .001), bloodstream infection (OR 4.59 [2.46-8.57], P < .001), and pneumonia (OR 9.76 [5.01-19.00], P < .001).

CONCLUSIONS

Several post-transplant predictors of ARDS development specific to the HSCT population were identified in the pre-hospital and early in-hospital domains. These findings can provide insights into causal mechanisms of ARDS development and be used to develop HSCT-specific risk prediction models.

SARS-CoV-2-Infection (COVID-19): Clinical Course, Viral Acute Respiratory Distress Syndrome (ARDS) and Cause(s) of Death

SARS-CoV-2-infected symptomatic patients often suffer from high fever and loss of appetite which are responsible for the deficit of fluids and of protein intake. Many patients admitted to the emergency room are, therefore, hypovolemic and hypoproteinemic and often suffer from respiratory distress accompanied by ground glass opacities in the CT scan of the lungs. Ischemic damage in the lung capillaries is responsible for the microscopic hallmark, diffuse alveolar damage (DAD) characterized by hyaline membrane formation, fluid invasion of the alveoli, and progressive arrest of blood flow in the pulmonary vessels. The consequences are progressive congestion, increase in lung weight, and progressive hypoxia (progressive severity of ARDS). Sequestration of blood in the lungs worsens hypovolemia and ischemia in different organs. This is most probably responsible for the recruitment of inflammatory cells into the ischemic peripheral tissues, the release of acute-phase mediators, and for the persistence of elevated serum levels of positive acute-phase markers and of hypoalbuminemia. Autopsy studies have been performed mostly in patients who died in the ICU after SARS-CoV-2 infection because of progressive acute respiratory distress syndrome (ARDS). In the death certification charts, after respiratory insufficiency, hypovolemic heart failure should be mentioned as the main cause of death.

Human Umbilical Cord Mesenchymal Stem Cells Promote Macrophage PD-L1 Expression and Attenuate Acute Lung Injury in Mice

BACKGROUND

Acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) remains a serious clinical problem but has no approved pharmacotherapy. Mesenchymal stem cells (MSCs) represent an attractive therapeutic tool for tissue damage and inflammation owing to their unique immunomodulatory properties. The present study aims to explore the therapeutic effect and underlying mechanisms of human umbilical cord MSCs (UC-MSCs) in ALI mice.

OBJECTIVE

In this study, we identify a novel mechanism for human umbilical cord-derived MSCs (UC-MSCs)-mediated immunomodulation through PGE2-dependent reprogramming of host macrophages to promote their PD-L1 expression. Our study suggests that UC-MSCs or primed-UC-MSCs offer new therapeutic approaches for lung inflammatory diseases.

METHODS

Lipopolysaccharide (LPS)-induced ALI mice were injected with 5×105 UC-MSCs via the tail vein after 4 hours of LPS exposure. After 24 hours of UC-MSC administration, the total protein concentration and cell number in the bronchoalveolar lavage fluid (BALF), and cytokine levels in the lung tissue were measured. Lung pathological changes and macrophage infiltration after UC-MSC treatment were analyzed. Moreover, in vitro co-culture experiments were performed to analyze cytokine levels of RAW264.7 cells and Jurkat T cells.

RESULTS

UC-MSC treatment significantly improved LPS-induced ALI, as indicated by decreased total protein exudation concentration and cell number in BALF, and reduced pathological damage in ALI mice. UC-MSCs could inhibit pro-inflammatory cytokine levels (IL-1β, TNF-α, MCP-1, IL-2, and IFN-γ), whereas enhancing anti-inflammatory cytokine IL-10 expression, as well as reduced macrophage infiltration into the injured lung tissue. Importantly, UC-MSC administration increased programmed cell death protein ligand 1 (PD-L1) expression in the lung macrophages. Mechanistically, UC-MSCs upregulated cyclooxygenase-2 (COX2) expression and prostaglandin E2 (PGE2) secretion in response to LPS stimulation. UC-MSCs reduced the inflammatory cytokine levels in murine macrophage Raw264.7 through the COX2/PGE2 axis. Furthermore, UC-MSC-derived PGE2 enhanced PD-L1 expression in RAW264.7 cells, which in turn promoted programmed cell death protein 1 (PD-1) expression and reduced IL-2 and IFN-γ production in Jurkat T cells.

CONCLUSION

Our results suggest that UC-MSCs attenuate ALI via PGE2-dependent reprogramming of macrophages to promote their PD-L1 expression.

Timing of ARDS Resolution (TARU): A Pragmatic Clinical Assessment of ARDS Resolution in the ICU

Purpose

Lack of a pragmatic outcome measures for acute respiratory distress syndrome (ARDS) resolution is a barrier to meaningful interventional trials of novel treatments. We evaluated a pragmatic, electronic health record (EHR)-based approach toward the clinical assessment of a novel outcome measure: ICU ARDS resolution.

Methods

We conducted a retrospective observational cohort study evaluating adult patients with moderate–severe ARDS admitted to the medical intensive care unit (ICU) at Mayo Clinic in Rochester, MN, from January 2001 through December 2010. We compared the association of ICU ARDS resolution vs non-resolution with mortality. ICU ARDS resolution was defined as improvement in P/F > 200 for at least 48 h or (if arterial blood gas unavailable) SpO₂:FiO₂ (S/F) > 235, or discharge prior to 48 h from first P/F > 200 without subsequent decline in P/F, as documented in EHR.

Results

Of the 254 patients included, ICU ARDS resolution was achieved in 179 (70%). Hospital mortality was lower in patients who met ICU ARDS resolution criteria as compared to those who did not (23% vs. 41%, p < 0.01). After adjusting for age, gender, and illness severity, the patients who met ICU ARDS resolution criteria had lower odds of hospital mortality [odds ratio 0.47, 95% CI 0.25–0.86; p = 0.015].

Conclusion

The electronic health record-based pragmatic measure of ICU ARDS resolution is associated with patient outcomes and may serve as an intermediate outcome assessing novel mechanistic treatments.

Acute respiratory distress syndrome: focusing on secondary injury

Acute respiratory distress syndrome (ARDS) is one of the most common severe diseases seen in the clinical setting. With the continuous exploration of ARDS in recent decades, the understanding of ARDS has improved. ARDS is not a simple lung disease but a clinical syndrome with various etiologies and pathophysiological changes. However, in the intensive care unit, ARDS often occurs a few days after primary lung injury or after a few days of treatment for other severe extrapulmonary diseases. Under such conditions, ARDS often progresses rapidly to severe ARDS and is difficult to treat. The occurrence and development of ARDS in these circumstances are thus not related to primary lung injury; the real cause of ARDS may be the “second hit” caused by inappropriate treatment. In view of the limited effective treatments for ARDS, the strategic focus has shifted to identifying potential or high-risk ARDS patients during the early stages of the disease and implementing treatment strategies aimed at reducing ARDS and related organ failure. Future research should focus on the prevention of ARDS.

2020 EACTS/ELSO/STS/AATS Expert Consensus on Post-cardiotomy Extracorporeal Life Support in Adult Patients

Post-cardiotomy extracorporeal life support (PC-ECLS) in adult patients has been used only rarely but recent data have shown a remarkable increase in its use, almost certainly due to improved technology, ease of management, growing familiarity with its capability and decreased costs. Trends in worldwide in-hospital survival, however, rather than improving, have shown a decline in some experiences, likely due to increased use in more complex, critically ill patients rather than to suboptimal management. Nevertheless, PC-ECLS is proving to be a valuable resource for temporary cardiocirculatory and respiratory support in patients who would otherwise most likely die. Because a comprehensive review of PC-ECLS might be of use for the practitioner, and possibly improve patient management in this setting, the authors have attempted to create a concise, comprehensive and relevant analysis of all aspects related to PC-ECLS, with a particular emphasis on indications, technique, management and avoidance of complications, appraisal of new approaches and ethics, education and training.

2020 EACTS/ELSO/STS/AATS expert consensus on post-cardiotomy extracorporeal life support in adult patients

Post-cardiotomy extracorporeal life support (PC-ECLS) in adult patients has been used only rarely but recent data have shown a remarkable increase in its use, almost certainly due to improved technology, ease of management, growing familiarity with its capability and decreased costs. Trends in worldwide in-hospital survival, however, rather than improving, have shown a decline in some experiences, likely due to increased use in more complex, critically ill patients rather than to suboptimal management. Nevertheless, PC-ECLS is proving to be a valuable resource for temporary cardiocirculatory and respiratory support in patients who would otherwise most likely die. Because a comprehensive review of PC-ECLS might be of use for the practitioner, and possibly improve patient management in this setting, the authors have attempted to create a concise, comprehensive and relevant analysis of all aspects related to PC-ECLS, with a particular emphasis on indications, technique, management, and avoidance of complications, appraisal of new approaches and ethics, education, and training.

Precision medicine in acute respiratory distress syndrome: workshop report and recommendations for future research

Acute respiratory distress syndrome (ARDS) is a devastating critical illness that can be triggered by a wide range of insults and remains associated with a high mortality of around 40%. The search for targeted treatment for ARDS has been disappointing, possibly due to the enormous heterogeneity within the syndrome. In this perspective from the European Respiratory Society research seminar on "Precision medicine in ARDS", we will summarise the current evidence for heterogeneity, explore the evidence in favour of precision medicine and provide a roadmap for further research in ARDS. There is evident variation in the presentation of ARDS on three distinct levels: 1) aetiological; 2) physiological and 3) biological, which leads us to the conclusion that there is no typical ARDS. The lack of a common presentation implies that intervention studies in patients with ARDS need to be phenotype aware and apply a precision medicine approach in order to avoid the lack of success in therapeutic trials that we faced in recent decades. Deeper phenotyping and integrative analysis of the sources of variation might result in identification of additional treatable traits that represent specific pathobiological mechanisms, or so-called endotypes.

Characteristics and Outcomes in Patients with Ventilator-Associated Pneumonia Who Do or Do Not Develop Acute Respiratory Distress Syndrome. An Observational Study

Ventilator-associated pneumonia (VAP) is a well-known complication of patients on invasive mechanical ventilation. The main cause of acute respiratory distress syndrome (ARDS) is pneumonia. ARDS can occur in patients with community-acquired or nosocomial pneumonia. Data regarding ARDS incidence, related pathogens, and specific outcomes in patients with VAP is limited. This is a cohort study in which patients with VAP were evaluated in an 800-bed tertiary teaching hospital between 2004 and 2016. Clinical outcomes, microbiological and epidemiological data were assessed among those who developed ARDS and those who did not. Forty-one (13.6%) out of 301 VAP patients developed ARDS. Patients who developed ARDS were younger and presented with higher prevalence of chronic liver disease. Pseudomonas aeruginosa was the most frequently isolated pathogen, but without any difference between groups. Appropriate empirical antibiotic treatment was prescribed to ARDS patients as frequently as to those without ARDS. Ninety-day mortality did not significantly vary among patients with or without ARDS. Additionally, patients with ARDS did not have significantly higher intensive care unit (ICU) and 28-day mortality, ICU, and hospital length of stay, ventilation-free days, and duration of mechanical ventilation. In summary, ARDS deriving from VAP occurs in 13.6% of patients. Although significant differences in clinical outcomes were not observed between both groups, further studies with a higher number of patients are needed due to the possibility of the study being underpowered.

2020 EACTS/ELSO/STS/AATS expert consensus on post-cardiotomy extracorporeal life support in adult patients

Post-cardiotomy extracorporeal life support (PC-ECLS) in adult patients has been used only rarely but recent data have shown a remarkable increase in its use, almost certainly due to improved technology, ease of management, growing familiarity with its capability and decreased costs. Trends in worldwide in-hospital survival, however, rather than improving, have shown a decline in some experiences, likely due to increased use in more complex, critically ill patients rather than to suboptimal management. Nevertheless, PC-ECLS is proving to be a valuable resource for temporary cardiocirculatory and respiratory support in patients who would otherwise most likely die. Because a comprehensive review of PC-ECLS might be of use for the practitioner, and possibly improve patient management in this setting, the authors have attempted to create a concise, comprehensive and relevant analysis of all aspects related to PC-ECLS, with a particular emphasis on indications, technique, management and avoidance of complications, appraisal of new approaches and ethics, education and training.

2020 EACTS/ELSO/STS/AATS Expert Consensus on Post-Cardiotomy Extracorporeal Life Support in Adult Patients

Post-cardiotomy extracorporeal life support (PC-ECLS) in adult patients has been used only rarely but recent data have shown a remarkable increase in its use, almost certainly due to improved technology, ease of management, growing familiarity with its capability and decreased costs. Trends in worldwide in-hospital survival, however, rather than improving, have shown a decline in some experiences, likely due to increased use in more complex, critically ill patients rather than to suboptimal management. Nevertheless, PC-ECLS is proving to be a valuable resource for temporary cardiocirculatory and respiratory support in patients who would otherwise most likely die. Because a comprehensive review of PC-ECLS might be of use for the practitioner, and possibly improve patient management in this setting, the authors have attempted to create a concise, comprehensive and relevant analysis of all aspects related to PC-ECLS, with a particular emphasis on indications, technique, management and avoidance of complications, appraisal of new approaches and ethics, education and training.

Postoperative but not intraoperative transfusions are associated with respiratory failure after pneumonectomy

OBJECTIVES

METHODS

We performed a retrospective cohort study using prospectively collected data on consecutive pneumonectomies between 2005 and 2015. Patient records were reviewed for intraoperative/postoperative exposures. Univariable and multivariable analyses were performed.

RESULTS

Of the 251 pneumonectomies performed during the study period, 24 (9.6%) patients suffered respiratory failure. Ninety-day mortality was 5.6% (n = 14) and was more likely in patients with respiratory failure (7/24 vs 7/227, P &lt; 0.001). Intraoperative and postoperative transfusions occurred in 42.2% (n = 106) and 44.6% (n = 112) of patients, respectively and were predominantly red blood cells. On univariable analysis, both intraoperative (P = 0.03) and postoperative transfusion (P = 0.004) were associated with a higher risk of respiratory failure. The multivariable model significantly predicted respiratory failure with an area under curve (AUC) = 0.88 (P = 0.001). On multivariable analysis, the only independent predictors of respiratory failure were postoperative transfusions [adjusted odds ratio (aOR) 6.54, 95% confidence interval (CI) 1.74–24.59; P = 0.005] and lower preoperative forced expiratory volume (adjusted OR 0.96, 95% CI 0.93–0.99; P = 0.03). Estimated blood loss was not significantly different (P = 0.91) between those with (median 800 ml, interquartile range 300–2000 ml) and without respiratory failure (median 800 ml, interquartile range 300–2000 ml).

CONCLUSIONS

Respiratory failure occurred in 9.6% of patients post-pneumonectomy and confers a higher risk of 90-day mortality. Postoperative (but not intraoperative) transfusion was the strongest independent predictor associated with respiratory failure. Intraoperative transfusion may be in reaction to active/unpredictable blood loss and may not be easily modifiable. However, postoperative transfusion may be modifiable and potentially avoidable. Transfusion thresholds should be assessed in light of potential cost-benefit trade-offs.

What factors predispose patients to acute respiratory distress syndrome?

Sepsis, pneumonia, and shock are the most common conditions predisposing to acute respiratory distress syndrome (ARDS) and certain host genetic variants have been associated with the development of ARDS. Risk modifiers include abuse of alcohol and tobacco, malnutrition, and obesity. The Lung Injury Prediction Score (LIPS) and the simplified Early Acute Lung Injury Score predict ARDS based on clinical and investigational criteria. Hospital-acquired ARDS may result from a medley factors of which high tidal volume ventilation, high oxygen concentration, and plasma transfusion are most commonly implicated. The Checklist for Lung Injury Prevention (CLIP) has been developed to ensure compliance with evidence-based practice that may affect ARDS occurrence. To date, no pharmacologic intervention has been shown to prevent ARDS

Incidence and Risk Factors of Pulmonary Complications after Robot-Assisted Laparoscopic Prostatectomy: A Retrospective Observational Analysis of 2208 Patients at a Large Single Center

Robot-assisted laparoscopic prostatectomy (RALP) is a minimally invasive technique for the treatment of prostate cancer. RALP requires the patient to be placed in the steep Trendelenburg position, along with pneumoperitoneum, which may increase the risk of postoperative pulmonary complications (PPCs). This large single-center retrospective study evaluated the incidence and risk factors of PPCs in 2208 patients who underwent RALP between 2014 and 2017. Patients were divided into those with (PPC group) and without (non-PPC group) PPCs. Postoperative outcomes were evaluated, and univariate and multivariate logistic regression analyses were performed to assess risk factors of PPCs. PPCs occurred in 682 patients (30.9%). Risk factors of PPCs included age (odds ratio [OR], 1.023; p = 0.001), body mass index (OR, 1.061; p = 0.001), hypoalbuminemia (OR, 1.653; p = 0.008), and positive end-expiratory pressure (PEEP) application (OR, 0.283; p < 0.001). The incidence of postoperative complications, rate of intensive care unit (ICU) admission, and duration of ICU stay were significantly greater in the PPC group than in the non-PPC group. In conclusion, the incidence of PPCs in patients who underwent RALP under pneumoperitoneum in the steep Trendelenburg position was 30.9%. Factors associated with PPCs included older age, higher body mass index, hypoalbuminemia, and lack of PEEP.

Fluid Management in Acute Respiratory Distress Syndrome

One of the defining features of acute respiratory distress syndrome (ARDS) is noncardiogenic pulmonary edema, resulting from increased permeability of the alveolar-capillary barrier and passage of protein-rich fluid into the interstitium and alveolar spaces. The loss of protein from the intravascular space disrupts the normal oncotic pressure differential and causes patients with ARDS to be particularly sensitive to the hydrostatic forces that correlate with intravascular volume. Conservative fluid management, in which diuretics are administered and intravenous fluid administration is minimized, may decrease hydrostatic pressure and increase serum oncotic pressure, potentially limiting the development of pulmonary edema. However, the cause of death in most patients with ARDS is multiorgan system failure, not hypoxemia, and the impact of conservative fluid management on the incidence of extrapulmonary organ failure during ARDS is unclear. These physiologic observations have led to a series of studies examining the impact of fluid management on the development of, resolution of, survival from, and long-term outcomes from ARDS. While questions remain, the current literature makes it clear that fluid management is an integral part of the care of patients with ARDS.

Outcomes of Patients Presenting with Mild Acute Respiratory Distress Syndrome

Editor’s Perspective

What We Already Know about This Topic

What This Article Tells Us That Is New

Background

Patients with initial mild acute respiratory distress syndrome are often underrecognized and mistakenly considered to have low disease severity and favorable outcomes. They represent a relatively poorly characterized population that was only classified as having acute respiratory distress syndrome in the most recent definition. Our primary objective was to describe the natural course and the factors associated with worsening and mortality in this population.

Methods

This study analyzed patients from the international prospective Large Observational Study to Understand the Global Impact of Severe Acute Respiratory Failure (LUNG SAFE) who had initial mild acute respiratory distress syndrome in the first day of inclusion. This study defined three groups based on the evolution of severity in the first week: “worsening” if moderate or severe acute respiratory distress syndrome criteria were met, “persisting” if mild acute respiratory distress syndrome criteria were the most severe category, and “improving” if patients did not fulfill acute respiratory distress syndrome criteria any more from day 2.

Results

Among 580 patients with initial mild acute respiratory distress syndrome, 18% (103 of 580) continuously improved, 36% (210 of 580) had persisting mild acute respiratory distress syndrome, and 46% (267 of 580) worsened in the first week after acute respiratory distress syndrome onset. Global in-hospital mortality was 30% (172 of 576; specifically 10% [10 of 101], 30% [63 of 210], and 37% [99 of 265] for patients with improving, persisting, and worsening acute respiratory distress syndrome, respectively), and the median (interquartile range) duration of mechanical ventilation was 7 (4, 14) days (specifically 3 [2, 5], 7 [4, 14], and 11 [6, 18] days for patients with improving, persisting, and worsening acute respiratory distress syndrome, respectively). Admissions for trauma or pneumonia, higher nonpulmonary sequential organ failure assessment score, lower partial pressure of alveolar oxygen/fraction of inspired oxygen, and higher peak inspiratory pressure were independently associated with worsening.

Conclusions

Most patients with initial mild acute respiratory distress syndrome continue to fulfill acute respiratory distress syndrome criteria in the first week, and nearly half worsen in severity. Their mortality is high, particularly in patients with worsening acute respiratory distress syndrome, emphasizing the need for close attention to this patient population.

Acute respiratory distress syndrome

The acute respiratory distress syndrome (ARDS) is a common cause of respiratory failure in critically ill patients and is defined by the acute onset of noncardiogenic pulmonary oedema, hypoxaemia and the need for mechanical ventilation. ARDS occurs most often in the setting of pneumonia, sepsis, aspiration of gastric contents or severe trauma and is present in ~10% of all patients in intensive care units worldwide. Despite some improvements, mortality remains high at 30-40% in most studies. Pathological specimens from patients with ARDS frequently reveal diffuse alveolar damage, and laboratory studies have demonstrated both alveolar epithelial and lung endothelial injury, resulting in accumulation of protein-rich inflammatory oedematous fluid in the alveolar space. Diagnosis is based on consensus syndromic criteria, with modifications for under-resourced settings and in paediatric patients. Treatment focuses on lung-protective ventilation; no specific pharmacotherapies have been identified. Long-term outcomes of patients with ARDS are increasingly recognized as important research targets, as many patients survive ARDS only to have ongoing functional and/or psychological sequelae. Future directions include efforts to facilitate earlier recognition of ARDS, identifying responsive subsets of patients and ongoing efforts to understand fundamental mechanisms of lung injury to design specific treatments.

Approaches and techniques to avoid development or progression of acute respiratory distress syndrome

PURPOSE OF REVIEW

Despite major improvement in ventilation strategies, hospital mortality and morbidity of the acute respiratory distress syndrome (ARDS) remain high. A lot of therapies have been shown to be ineffective for established ARDS. There is a growing interest in strategies aiming at avoiding development and progression of ARDS.

RECENT FINDINGS

Recent advances in this field have explored identification of patients at high-risk, nonspecific measures to limit the risks of inflammation, infection and fluid overload, prevention strategies of ventilator-induced lung injury and patient self-inflicted lung injury, and pharmacological treatments.

SUMMARY

There is potential for improvement in the management of patients admitted to intensive care unit to reduce ARDS incidence. Apart from nonspecific measures, prevention of ventilator-induced lung injury and patient self-inflicted lung injury are of major importance.

The Incremental Burden of Acute Respiratory Distress Syndrome: Long-term Follow-up of a Population-Based Nested Case-Control Study

OBJECTIVE

To evaluate the long-term survival of patients at similar risk for hospital-acquired acute respiratory distress syndrome (ARDS) who did and did not develop ARDS.

METHODS

We conducted long-term follow-up of a population-based nested case-control study in a consecutive cohort of adult Olmsted County, Minnesota, patients admitted from January 1, 2001, through December 31, 2010. Patients in whom ARDS developed during their hospital stay (cases) were matched to similar-risk patients without ARDS (controls) by 6 characteristics: age, sex, sepsis, high-risk surgery, ratio of oxygen saturation to fraction of inspired oxygen, and ARDS risk according to the Lung Injury Prediction Score. Hospital mortality, discharge disposition, and long-term survival were compared.

RESULTS

Patients who developed hospital-acquired ARDS (n=400) had higher hospital mortality than at-risk controls (n=400) (35% vs 5%; P<.001). Among hospital survivors (252 matched pairs), ARDS cases were more likely to be discharged to rehabilitation (13% vs 4%) and long-term care (30% vs 15%) facilities, whereas more controls were discharged home (71% vs 41%). After discharge, differences in survival persisted beyond 90 days (adjusted hazard ratio [HR], 1.76; 95% CI, 1.2-2.5; P=.002) and 6 months (adjusted HR, 1.73; 95% CI, 1.2-2.6; P<.001).

CONCLUSION

These results suggest that in a population-based matched case-control study of patients with similar characteristics at the time of hospital admission, those who developed hospital-acquired ARDS had worse long-term survival.

The preventive effect of antiplatelet therapy in acute respiratory distress syndrome: a meta-analysis

Background

Acute respiratory distress syndrome (ARDS) is a life-threatening condition with high mortality that imposes a serious medical burden. Antiplatelet therapy is a potential strategy for preventing ARDS in patients with a high risk of developing this condition. A meta-analysis was performed to investigate whether antiplatelet therapy could reduce the incidence of newly developed ARDS and its associated mortality in high-risk patients.

Methods

The Cochrane Central Register of Controlled Trials (CENTRAL), PubMed, Embase, Medline, and the Web of Science were searched for published studies from inception to 26 October 2017. We included randomized clinical trials, cohort studies and case-control studies investigating antiplatelet therapy in adult patients presenting to the hospital or ICU with a high risk for ARDS. Baseline patient characteristics, interventions, controls and outcomes were extracted. Our primary outcome was the incidence of newly developed ARDS in high-risk patients. Secondary outcomes were hospital and ICU mortality. A random-effects or fixed-effects model was used for quantitative synthesis.

Results

We identified nine eligible studies including 7660 high-risk patients who received antiplatelet therapy. Based on seven observational studies, antiplatelet therapy was associated with a decreased incidence of ARDS (odds ratio (OR) 0.68, 95% confidence interval (CI) 0.52–0.88; I² = 68.4%, p = 0.004). In two randomized studies, no significant difference was found in newly developed ARDS between the antiplatelet groups and placebo groups (OR 1.32, 95% CI 0.72–2.42; I² = 0.0%, p = 0.329). Antiplatelet therapy did not reduce hospital mortality in randomized studies (OR 1.15, 95% CI 0.58–2.27; I² = 0.0%; p = 0.440) or observational studies (OR 0.80, 95% CI 0.62–1.03; I² = 31.9%, p = 0.221).

Conclusions

Antiplatelet therapy did not significantly decrease hospital mortality in high-risk patients. However, whether antiplatelet therapy is associated with a decreased incidence of ARDS in patients at a high risk of developing the condition remains unclear.

Electronic supplementary material

The online version of this article (10.1186/s13054-018-1988-y) contains supplementary material, which is available to authorized users.

Fifty Years of Research in ARDS. Is Acute Respiratory Distress Syndrome a Preventable Disease?

Despite significant advances in our understanding and management of patients with acute respiratory distress syndrome (ARDS), the morbidity and mortality from ARDS remains high. Given the limited number of effective treatments for established ARDS, the strategic focus of ARDS research has shifted toward identifying patients with or at high risk of ARDS early in the course of the underlying illness, when strategies to reduce the development and progression of ARDS and associated organ failures can be systematically evaluated. In this review, we summarize the rationale, current evidence, and future directions in ARDS prevention.

Epidemiology of Acute Respiratory Distress Syndrome Following Hematopoietic Stem Cell Transplantation

OBJECTIVES

Pulmonary complications are common following hematopoietic stem cell transplantation. Numerous idiopathic post-transplantation pulmonary syndromes have been described. Patients at the severe end of this spectrum may present with hypoxemic respiratory failure and pulmonary infiltrates, meeting criteria for acute respiratory distress syndrome. The incidence and outcomes of acute respiratory distress syndrome in this setting are poorly characterized.

DESIGN

Retrospective cohort study.

SETTING

Mayo Clinic, Rochester, MN.

PATIENTS

Patients undergoing autologous and allogeneic hematopoietic stem cell transplantation between January 1, 2005, and December 31, 2012.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Patients were screened for acute respiratory distress syndrome development within 1 year of hematopoietic stem cell transplantation. Acute respiratory distress syndrome adjudication was performed in accordance with the 2012 Berlin criteria. In total, 133 cases of acute respiratory distress syndrome developed in 2,635 patients undergoing hematopoietic stem cell transplantation (5.0%). Acute respiratory distress syndrome developed in 75 patients (15.6%) undergoing allogeneic hematopoietic stem cell transplantation and 58 patients (2.7%) undergoing autologous hematopoietic stem cell transplantation. Median time to acute respiratory distress syndrome development was 55.4 days (interquartile range, 15.1-139 d) in allogeneic hematopoietic stem cell transplantation and 14.2 days (interquartile range, 10.5-124 d) in autologous hematopoietic stem cell transplantation. Twenty-eight-day mortality was 46.6%. At 12 months following hematopoietic stem cell transplantation, 89 patients (66.9%) who developed acute respiratory distress syndrome had died. Only 7 of 133 acute respiratory distress syndrome cases met criteria for engraftment syndrome and 15 for diffuse alveolar hemorrhage.

CONCLUSIONS

Acute respiratory distress syndrome is a frequent complication following hematopoietic stem cell transplantation, dramatically influencing patient-important outcomes. Most cases of acute respiratory distress syndrome following hematopoietic stem cell transplantation do not meet criteria for a more specific post-transplantation pulmonary syndrome. These findings highlight the need to better understand the risk factors underlying acute respiratory distress syndrome in this population, thereby facilitating the development of effective prevention strategies.

RBC transfusion is associated with increased risk of respiratory failure after pneumonectomy

BACKGROUND AND OBJECTIVES

Pneumonectomy is associated with high risk of respiratory complications. Our objective was to determine if transfusions are associated with increased rate of ARDS and respiratory failure in adults undergoing elective pneumonectomy.

METHODS

Retrospective cohort study of consecutive pneumonectomies undertaken at a tertiary hospital (2003-2013). Multivariable logistic regression was performed to adjust for confounding factors.

RESULTS

ARDS and respiratory failure occurred in 12.4% (n = 20) and 19.2% (n = 31) of 161 pneumonectomy patients, respectively, and were more likely to occur in transfused patients (P = 0.03, P < 0.001). pRBCs, FFP and platelets were transfused in 27% (n = 43), 6% (n = 9), and 2% (n = 3), respectively. On multivariable analyses utilizing blood products as continuous and binary variables, pRBC use was the only independent predictor of ARDS with odds ratio (OR) = 1.23 (95%CI:1.08-1.39, P = 0.002) and OR = 2.45 (95%CI:1.10-5.49, P = 0.03), respectively. On multivariable analyses utilizing blood products as continuous and binary variables, pRBCs were the only independent predictor of respiratory failure with OR = 1.37 (95%CI:1.16-1.60, P < 0.001) and OR = 3.17 (95%CI:1.25-8.02, P = 0.02), respectively.

CONCLUSIONS

Peri-operative pRBC use appears to be an independent risk factor for ARDS and respiratory failure after pneumonectomy. There is a significant dose-response relationship. Platelets and FFP did not appear to increase ARDS risk but this may be due to low utilization.

Influence of intraoperative positive end-expiratory pressure level on pulmonary complications in emergency major trauma surgery

INTRODUCTION

Pulmonary complications have a major impact on the morbidity and mortality of critically ill patients with multiple trauma. Intraoperative protective ventilation with low tidal volume may prevent lung injury and infection, whereas the role of positive end-expiratory pressure (PEEP) levels is unclear. The aim of this study was to evaluate the influence of different intraoperative PEEP levels on incidence of pulmonary complications after emergency trauma surgery.

MATERIAL AND METHODS

We retrospectively analysed data of multiple trauma patients who underwent emergency surgery within 24 h after injury in our level I trauma centre (n = 86). On the basis of their intraoperative PEEP level, patients were divided into a low PEEP group with a PEEP of < 8 mbar and a high PEEP group with a PEEP of 8 mbar or higher.

RESULTS

Besides differences in body mass index and preoperative oxygenation, there were no differences in patients' baseline data. There was a significant difference between incidence of pneumonia within 7 days after trauma surgery, with an incidence 26.7% in the low PEEP group and 7.3% in the high PEEP group (p = 0.02). The low PEEP group had higher pulmonary infection scores at days 3 and 5 after surgery. Oxygenation was better in the higher PEEP group postoperatively. There was no difference with respect to the incidence of acute respiratory distress syndrome, the mortality up until hospital discharge or haemodynamic parameters between groups.

CONCLUSIONS

Higher PEEP levels were associated with perioperative improvement of oxygenation and a lower incidence of pneumonia, without impairment of haemodynamics. Additional studies should be initiated to confirm these observations.

Selected Disorders of the Respiratory System

Respiration and gas exchange require coordination between the chest wall, lungs, central nervous system, and pulmonary circulation. A disruption within any one of these systems or a change in the relationship between systems can result in impairments of ventilation, perfusion, or gas exchange. These disruptions can result in debilitating acute and chronic respiratory disorders. This chapter discusses the etiology, epidemiology, clinical presentation, diagnostic criteria, management, and notable public health implications of respiratory system disorders not addressed in prior chapters. Topic areas covered include acute respiratory distress syndrome (ARDS), pulmonary hypertension, pneumothorax, pleural effusion, interstitial lung disease, bronchiectasis, atelectasis, and pulmonary sarcoidosis.

Acute respiratory distress syndrome following cardiovascular surgery: current concepts and novel therapeutic approaches

PURPOSE OF REVIEW

This review gives an update on current treatment options and novel concepts on the prevention and treatment of the acute respiratory distress syndrome (ARDS) in cardiovascular surgery patients.

RECENT FINDINGS

The only proven beneficial therapeutic options in ARDS are those that help to prevent further ventilator-induced lung injury, such as prone position, use of lung-protective ventilation strategies, and extracorporeal membrane oxygenation. In the future also new approaches like mesenchymal cell therapy, activation of hypoxia-elicited transcription factors or targeting of purinergic signaling may be successful outside the experimental setting. Owing to the so far limited treatment options, it is of great importance to determine patients at risk for developing ARDS already perioperatively. In this context, serum biomarkers and lung injury prediction scores could be useful.

SUMMARY

Preventing ARDS as a severe complication in the cardiovascular surgery setting may help to reduce morbidity and mortality. As cardiovascular surgery patients are of greater risk to develop ARDS, preventive interventions should be implemented early on. Especially, use of low tidal volumes, avoiding of fluid overload and restrictive blood transfusion regimes may help to prevent ARDS.

Early intervention of patients at risk for acute respiratory failure and prolonged mechanical ventilation with a checklist aimed at the prevention of organ failure: protocol for a pragmatic stepped-wedged cluster trial of PROOFCheck

INTRODUCTION

Acute respiratory failure (ARF) often presents and progresses outside of the intensive care unit. However, recognition and treatment of acute critical illness is often delayed with inconsistent adherence to evidence-based care known to decrease the duration of mechanical ventilation (MV) and complications of critical illness. The goal of this trial is to determine whether the implementation of an electronic medical record-based early alert for progressive respiratory failure coupled with a checklist to promote early compliance to best practice in respiratory failure can improve the outcomes of patients at risk for prolonged respiratory failure and death.

METHODS AND ANALYSIS

A pragmatic stepped-wedged cluster clinical trial involving 6 hospitals is planned. The study will include adult hospitalised patients identified as high risk for MV >48 hours or death because they were mechanically ventilated outside of the operating room or they were identified as high risk for ARF on the Accurate Prediction of PROlonged VEntilation (APPROVE) score. Patients with advanced directives limiting intubation will be excluded. The intervention will consist of (1) automated identification and notification of clinician of high-risk patients by APPROVE or by invasive MV and (2) checklist of evidence-based practices in ARF (Prevention of Organ Failure Checklist-PROOFCheck). APPROVE and PROOFCheck will be developed in the pretrial period. Primary outcome is hospital mortality. Secondary outcomes include length of stay, ventilator and organ failure-free days and 6-month and 12-month mortality. Predefined subgroup analysis of patients with limitation of aggressive care after study entry is planned. Generalised estimating equations will be used to compare patients in the intervention phase with the control phase, adjusting for clustering within hospitals and time.

ETHICS AND DISSEMINATION

The study was approved by the institutional review boards. Results will be published in peer-reviewed journals and presented at international meetings.

TRIAL REGISTRATION NUMBER

NCT02488174.

Effect of Antiplatelet Therapy on Acute Respiratory Distress Syndrome and Mortality in Critically Ill Patients: A Meta-Analysis

BACKGROUND

Antiplatelet agents are commonly used for cardiovascular diseases, but their pleiotropic effects in critically ill patients are controversial. We therefore performed a meta-analysis of cohort studies to investigate the effect of antiplatelet therapy in the critically ill.

METHODS

Nine cohort studies, retrieved from PubMed and Embase before November 2015, involving 14,612 critically ill patients and 4765 cases of antiplatelet users, were meta-analysed. The main outcome was hospital or 30-day mortality. Secondary outcome was acute respiratory distress syndrome (ARDS) or acute lung injury (ALI). Random- or fixed-effect models were taken for quantitative synthesis of the data.

RESULTS

Antiplatelet therapy was associated with decreased mortality (odds ratio (OR) 0.61; 95% confidence interval (CI), 0.52-0.71; I2 = 0%; P <0. 001) and ARDS/ALI (OR 0.64; 95% CI, 0.50-0.82; I2 = 0%; P <0. 001). In every stratum of subgroups, similar findings on mortality reduction were consistently observed in critically ill patients.

CONCLUSIONS

Antiplatelet therapy is associated with reduced mortality and lower incidence of ARDS/ALI in critically ill patients, particularly those with predisposing conditions such as high-risk surgery, trauma, pneumonia, and sepsis. However, it remains unclear whether similar findings can be observed in the unselected and broad population with critical illness.

Influence of different electrode belt positions on electrical impedance tomography imaging of regional ventilation: a prospective observational study

Background

Electrical impedance tomography (EIT) is a non-invasive bedside tool which allows an individualized ventilator strategy by monitoring tidal ventilation and lung aeration. EIT can be performed at different cranio-caudal thoracic levels, but data are missing about the optimal belt position. The main goal of this prospective observational study was to evaluate the impact of different electrode layers on tidal impedance variation in relation to global volume changes in order to propose a proper belt position for EIT measurements.

Methods

EIT measurements were performed in 15 mechanically ventilated intensive care patients with the electrode belt at different thoracic layers (L1-L7). All respiratory and hemodynamic parameters were recorded. Blood gas analyses were obtained once at the beginning of EIT examination. Off-line tidal impedance variation/tidal volume (TV/VT) ratio was calculated, and specific patterns of impedance distribution due to automatic and user-defined adjustment of the colour scale for EIT images were identified.

Results

TV/VT ratio is the highest at L1. It decreases in caudal direction. At L5, the decrease of TV/VT ratio is significant. We could identify patterns of diaphragmatic interference with ventilation-related impedance changes, which owing to the automatically adjusted colour scales are not obvious in the regularly displayed EIT images.

Conclusions

The clinical usability and plausibility of EIT measurements depend on proper belt position, proper impedance visualisation, correct analysis and data interpretation. When EIT is used to estimate global parameters like VT or changes in end-expiratory lung volume, the best electrode plane is between the 4th and 5th intercostal space. The specific colour coding occasionally suppresses user-relevant information, and manual rescaling of images is necessary to visualise this information.

Comparison of community-acquired, hospital-acquired, and intensive care unit-acquired acute respiratory distress syndrome: a prospective observational cohort study

Introduction

Acute respiratory distress syndrome (ARDS) is a syndrome characterized by diffuse pulmonary edema and severe hypoxemia that usually occurs after an injury such as sepsis, aspiration and pneumonia. Little is known about the relation between the setting where the syndrome developed and outcomes in ARDS patients.

Methods

This is a 1-year prospective observational study conducted at a tertiary referred hospital. ARDS was defined by the Berlin criteria. Community-acquired ARDS, hospital-acquired ARDS and intensive care unit (ICU)-acquired ARDS were defined as ARDS occurring within 48 hours of hospital or ICU admission, more than 48 hours after hospital admission and ICU admission. The primary and secondary outcomes were short- and long- term mortality rates and ventilator-free and ICU-free days.

Results

Of the 3002 patients screened, 296 patients had a diagnosis of ARDS, including 70 (23.7 %) with community-acquired ARDS, 83 (28 %) with hospital-acquired ARDS, and 143 (48.3 %) with ICU-acquired ARDS. The overall ICU mortality rate was not significantly different in mild, moderate and severe ARDS (50 %, 50 % and 56 %, p = 0.25). The baseline characteristics were similar other than lower rate of liver disease and metastatic malignancy in community-acquired ARDS than in hospital-acquired and ICU-acquired ARDS. A multiple logistic regression analysis indicated that age, sequential organ function assessment score and community-acquired ARDS were independently associated with hospital mortality. For community-acquired, hospital-acquired and ICU-acquired ARDS, ICU mortality rates were 37 % 61 % and 52 %; hospital mortality rates were 49 %, 74 % and 68 %. The ICU and hospital mortality rates of community-acquired ARDS were significantly lower than hospital-acquired and ICU-acquired ARDS (p = 0.001 and p = 0.001). The number of ventilator-free days was significantly lower in ICU-acquired ARDS than in community-acquired and hospital-acquired ARDS (11 ± 9, 16 ± 9, and 14 ± 10 days, p = 0.001). The number of ICU-free days was significantly higher in community-acquired ARDS than in hospital-acquired and ICU-acquired ARDS (8 ± 10, 4 ± 8, and 3 ± 6 days, p = 0.001).

Conclusions

Community-acquired ARDS have lower short- and long-term mortality rates than hospital-acquired or ICU-acquired ARDS.

Postoperative Critical Care of the Adult Cardiac Surgical Patient. Part I: Routine Postoperative Care

OBJECTIVES

Cardiac surgery, including coronary artery bypass, cardiac valve, and aortic procedures, is among the most common surgical procedures performed in the United States. Successful outcomes after cardiac surgery depend on optimum postoperative critical care. The cardiac intensivist must have a comprehensive understanding of cardiopulmonary physiology and the sequelae of cardiopulmonary bypass. In this concise review, targeted at intensivists and surgeons, we discuss the routine management of the postoperative cardiac surgical patient.

DATA SOURCE AND SYNTHESIS

Narrative review of relevant English-language peer-reviewed medical literature.

CONCLUSIONS

Critical care of the cardiac surgical patient is a complex and dynamic endeavor. Adequate fluid resuscitation, appropriate inotropic support, attention to rewarming, and ventilator management are key components. Patient safety is enhanced by experienced personnel, a structured handover between the operating room and ICU teams, and appropriate transfusion strategies.

Prevention of acute respiratory distress syndrome

PURPOSE OF REVIEW

The paucity of effective therapeutic interventions in patients with the acute respiratory distress syndrome (ARDS) combined with overwhelming evidence on the importance of timely implementation of effective therapies to critically ill patients has resulted in a recent shift in ARDS research. Increasingly, efforts are being directed toward early identification of patients at risk with a goal of prevention and early treatment, prior to development of the fully established syndrome. The focus of the present review is on the prevention of ARDS in patients without this condition at the time of their healthcare encounter.

RECENT FINDINGS

The primary thematic categories presented in the present review article include early identification of patients at risk of developing ARDS, optimization of care delivery and its impact on the incidence of ARDS, pharmacological prevention of ARDS, prevention of postoperative ARDS, and challenges and opportunities with ARDS prevention studies.

SUMMARY

Recent improvements in clinical care delivery have been associated with a decrease in the incidence of hospital-acquired ARDS. Despite the initial challenges, research in ARDS prevention has become increasingly feasible with several randomized controlled trials on ARDS prevention completed or on the way.

Lung Injury Prediction Score Is Useful in Predicting Acute Respiratory Distress Syndrome and Mortality in Surgical Critical Care Patients

Background. Lung injury prediction score (LIPS) is valuable for early recognition of ventilated patients at high risk for developing acute respiratory distress syndrome (ARDS). This study analyzes the value of LIPS in predicting ARDS and mortality among ventilated surgical patients. Methods. IRB approved, prospective observational study including all ventilated patients admitted to the surgical intensive care unit at a single tertiary center over 6 months. ARDS was defined using the Berlin criteria. LIPS were calculated for all patients and analyzed. Logistic regression models evaluated the ability of LIPS to predict development of ARDS and mortality. A receiver operator characteristic (ROC) curve demonstrated the optimal LIPS value to statistically predict development of ARDS. Results. 268 ventilated patients were observed; 141 developed ARDS and 127 did not. The average LIPS for patients who developed ARDS was 8.8 ± 2.8 versus 5.4 ± 2.8 for those who did not (p < 0.001). An ROC area under the curve of 0.79 demonstrates LIPS is statistically powerful for predicting ARDS development. Furthermore, for every 1-unit increase in LIPS, the odds of developing ARDS increase by 1.50 (p < 0.001) and odds of ICU mortality increase by 1.22 (p < 0.001). Conclusion. LIPS is reliable for predicting development of ARDS and predicting mortality in critically ill surgical patients.

Aspirin therapy in patients with acute respiratory distress syndrome (ARDS) is associated with reduced intensive care unit mortality: a prospective analysis

Introduction

Acute respiratory distress syndrome (ARDS) is a common clinical syndrome with high mortality and long-term morbidity. To date there is no effective pharmacological therapy. Aspirin therapy has recently been shown to reduce the risk of developing ARDS, but the effect of aspirin on established ARDS is unknown.

Methods

In a single large regional medical and surgical ICU between December 2010 and July 2012, all patients with ARDS were prospectively identified and demographic, clinical, and laboratory variables were recorded retrospectively. Aspirin usage, both pre-hospital and during intensive care unit (ICU) stay, was included. The primary outcome was ICU mortality. We used univariate and multivariate logistic regression analyses to assess the impact of these variables on ICU mortality.

Results

In total, 202 patients with ARDS were included; 56 (28%) of these received aspirin either pre-hospital, in the ICU, or both. Using multivariate logistic regression analysis, aspirin therapy, given either before or during hospital stay, was associated with a reduction in ICU mortality (odds ratio (OR) 0.38 (0.15 to 0.96) P = 0.04). Additional factors that predicted ICU mortality for patients with ARDS were vasopressor use (OR 2.09 (1.05 to 4.18) P = 0.04) and APACHE II score (OR 1.07 (1.02 to 1.13) P = 0.01). There was no effect upon ICU length of stay or hospital mortality.

Conclusion

Aspirin therapy was associated with a reduced risk of ICU mortality. These data are the first to demonstrate a potential protective role for aspirin in patients with ARDS. Clinical trials to evaluate the role of aspirin as a pharmacological intervention for ARDS are needed.

A prospective evaluation of ventilator-associated conditions and infection-related ventilator-associated conditions

BACKGROUND

The Centers for Disease Control and Prevention has shifted policy away from using ventilator-associated pneumonia (VAP) and toward using ventilator-associated conditions (VACs) as a marker of ICU quality. To date, limited prospective data regarding the incidence of VAC among medical and surgical ICU patients, the ability of VAC criteria to capture patients with VAP, and the potential clinical preventability of VACs are available.

METHODS

This study was a prospective 12-month cohort study (January 2013 to December 2013).

RESULTS

We prospectively surveyed 1,209 patients ventilated for ≥ 2 calendar days. Sixty-seven VACs were identified (5.5%), of which 34 (50.7%) were classified as an infection-related VAC (IVAC) with corresponding rates of 7.0 and 3.6 per 1,000 ventilator days, respectively. The mortality rate of patients having a VAC was significantly greater than that of patients without a VAC (65.7% vs 14.4%, P < .001). The most common causes of VACs included IVACs (50.7%), ARDS (16.4%), pulmonary edema (14.9%), and atelectasis (9.0%). Among IVACs, 44.1% were probable VAP and 17.6% were possible VAP. Twenty-five VACs (37.3%) were adjudicated to represent potentially preventable events. Eighty-six episodes of VAP occurred in 84 patients (10.0 of 1,000 ventilator days) during the study period. The sensitivity of the VAC criteria for the detection of VAP was 25.9% (95% CI, 16.7%-34.5%).

CONCLUSIONS

Although relatively uncommon, VACs are associated with greater mortality and morbidity when they occur. Most VACs represent nonpreventable events, and the VAC criteria capture a minority of VAP episodes.

Adverse in-hospital events are associated with increased in-hospital mortality and length of stay in patients with or at risk of acute respiratory distress syndrome

OBJECTIVE

To explore the effect of various adverse hospital events on short- and long-term outcomes in a cohort of acutely ill hospitalized patients.

PATIENTS AND METHODS

In a secondary analysis of a retrospective cohort of acutely ill hospitalized patients with sepsis, shock, or pneumonia or undergoing high-risk surgery who were at risk for or had developed acute respiratory distress syndrome between 2001 and 2010, the effects of potentially preventable hospital exposures and adverse events (AEs) on in-hospital and intensive care unit (ICU) mortality, length of stay, and long-term survival were analyzed. Adverse effects chosen for inclusion were inadequate empiric antimicrobial coverage, hospital-acquired aspiration, medical or surgical misadventure, inappropriate blood product transfusion, and injurious tidal volume while on mechanical ventilation.

RESULTS

In 828 patients analyzed, the distribution of 0, 1, 2, and 3 or more cumulative AEs was 521 (63%), 126 (15%), 135 (16%), and 46 (6%) patients, respectively. The adjusted odds ratios (95% CI) for in-hospital mortality in patients who had 1, 2, and 3 or more AEs were 0.9 (0.5-1.7), 0.9 (0.5-1.6), and 1.4 (0.6-3.3), respectively. One AE increased the length of stay, difference between means (95% CI), in the hospital by 8.7 (3.8-13.7) days and in the ICU by 2.4 (0.6-4.2) days.

CONCLUSION

Potentially preventable hospital exposure to AEs is associated with prolonged ICU and hospital lengths of stay. Implementation of effective patient safety interventions is of utmost priority in acute care hospitals.

Recent advances in mechanical ventilation in patients with acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is characterised by different degrees of severity and different stages. Understanding these differences can help to better adapt the ventilatory settings to protect the lung from ventilator-induced lung injury by reducing hyperinflation or keeping the lung open when it is possible. The same therapies may be useful and beneficial in certain forms of ARDS, and risky or harmful at other stages: this includes high positive end-expiratory pressure, allowance of spontaneous breathing activity or use of noninvasive ventilation. The severity of the disease is the primary indicator to individualise treatment. Monitoring tools such as oesophageal pressure or lung volume measurements may also help to set the ventilator. At an earlier stage, an adequate lung protective strategy may also help to prevent the development of ARDS.

Preventing ARDS: progress, promise, and pitfalls

Advances in critical care practice have led to a substantial decline in the incidence of ARDS over the past several years. Low tidal volume ventilation, timely resuscitation and antimicrobial administration, restrictive transfusion practices, and primary prevention of aspiration and nosocomial pneumonia have likely contributed to this reduction. Despite decades of research, there is no proven pharmacologic treatment of ARDS, and mortality from ARDS remains high. Consequently, recent initiatives have broadened the scope of lung injury research to include targeted prevention of ARDS. Prediction scores have been developed to identify patients at risk for ARDS, and clinical trials testing aspirin and inhaled budesonide/formoterol for ARDS prevention are ongoing. Future trials aimed at preventing ARDS face several key challenges. ARDS has not been validated as an end point for pivotal clinical trials, and caution is needed when testing toxic therapies that may prevent ARDS yet potentially increase mortality.

Evolving epidemiology and definitions of the acute respiratory distress syndrome and early acute lung injury

This article reviews the evolving definitions and epidemiology of the acute respiratory distress syndrome (ARDS) and highlights current efforts to improve identification of high-risk patients, thus to target prevention and early treatment before progression to ARDS. This information will be important for general practitioners and intensivists interested in improving the care of patients at risk for ARDS, and clinical researchers interested in designing clinical trials targeting the prevention and early treatment of acute lung injury.