Effect of acute lung injury and acute respiratory distress syndrome on outcome in critically ill trauma patients

Hospital Outcomes in Patients Who Developed Acute Respiratory Distress Syndrome After Community-Acquired Pneumonia

Purpose: To identify risk factors for and outcomes in acute respiratory distress syndrome (ARDS) in patients hospitalized with community-acquired pneumonia (CAP). Methods: This is a retrospective study using the Premier Healthcare Database between 2016 and 2020. Patients diagnosed with pneumonia, requiring mechanical ventilation (MV), antimicrobial therapy, and hospital admission ≥2 days were included. Multivariable regression models were used for outcomes including in-hospital mortality, hospital length of stay (LOS), intensive care unit (ICU) LOS, and days on MV. Results: 1924 (2.7%) of 72 107 patients with CAP developed ARDS. ARDS was associated with higher mortality (33.7% vs 18.9%; adjusted odds ratio 2.4; 95% confidence interval [CI] 2.16-2.66), longer hospital LOS (13 vs 9 days; adjusted incidence risk ratio (aIRR) 1.24; 95% CI 1.20-1.27), ICU LOS (9 vs 5 days; aIRR 1.51; 95% CI 1.46-1.56), more MV days (8 vs 5; aIRR 1.54; 95% CI 1.48-1.59), and increased hospitalization cost ($46 459 vs $29 441; aIRR 1.50; 95% CI 1.45-1.55). Conclusion: In CAP, ARDS was associated with worse in-patient outcomes in terms of mortality, LOS, and hospitalization cost. Future studies are needed to explore outcomes in patients with CAP with ARDS and explore risk factors for development of ARDS after CAP.

Identification of genetic profile and biomarkers involved in acute respiratory distress syndrome

PURPOSE

The purpose of this study was to profile genetic causal factors of acute respiratory distress syndrome (ARDS) and early predict patients at high ARDS risk.

METHODS

We performed a phenome-wide Mendelian Randomization analysis through summary statistics of an ARDS genome-wide association study (1250 cases and 1583 controls of European ancestry) and 33,150 traits. Transcriptomic data from human blood and lung tissues of a preclinical mouse model were used to validate biomarkers, which were further used to construct a prediction model and nomogram.

RESULTS

A total of 1736 traits, including 1223 blood RNA, 159 plasma proteins, and 354 non-gene phenotypes (classified by Biochemistry, Anthropometry, Disease, Nutrition and Habit, Immunology, and Treatment), exhibited a potentially causal relationship with ARDS development, which were accessible through a user-friendly interface platform called CARDS (Causal traits for Acute Respiratory Distress Syndrome). Regarding candidate blood RNA, four genes were validated, namely TMEM176B, SLC2A5, CDC45, and VSIG8, showing differential expression in blood of ARDS patients compared to controls, as well as dynamic expression in mouse lung tissues. Importantly, the addition of four blood genes and five immune cell proportions significantly improved the prediction performance of ARDS development, with 0.791 of the area under the curve from receiver-operator characteristic, compared to 0.725 for the basic model consisting of Acute Physiology and Chronic Health Evaluation (APACHE) III Score, sex, body mass index, bacteremia, and sepsis. A model-based nomogram was also developed for the clinical practice.

CONCLUSION

This study identifies a wide range of ARDS relevant factors and develops a promising prediction model, enhancing early clinical management and intervention for ARDS development.

Subphenotypes of Acute Respiratory Distress Syndrome: Advancing Towards Precision Medicine

Acute respiratory distress syndrome (ARDS) is a common cause of severe hypoxemia defined by the acute onset of bilateral non-cardiogenic pulmonary edema. The diagnosis is made by defined consensus criteria. Supportive care, including prevention of further injury to the lungs, is the only treatment that conclusively improves outcomes. The inability to find more advanced therapies is due, in part, to the highly sensitive but relatively non-specific current syndromic consensus criteria, combining a heterogenous population of patients under the umbrella of ARDS. With few effective therapies, the morality rate remains 30% to 40%. Many subphenotypes of ARDS have been proposed to cluster patients with shared combinations of observable or measurable traits. Subphenotyping patients is a strategy to overcome heterogeneity to advance clinical research and eventually identify treatable traits. Subphenotypes of ARDS have been proposed based on radiographic patterns, protein biomarkers, transcriptomics, and/or machine-based clustering of clinical and biological variables. Some of these strategies have been reproducible across patient cohorts, but at present all have practical limitations to their implementation. Furthermore, there is no agreement on which strategy is the most appropriate. This review will discuss the current strategies for subphenotyping patients with ARDS, including the strengths and limitations, and the future directions of ARDS subphenotyping.

Early Internal Fixation of Concomitant Clavicle Fractures in Severe Thoracic Trauma Prevents Posttraumatic Pneumonia

BACKGROUND

Severe thoracic trauma can lead to pulmonary restriction, loss of lung volume, and difficulty with ventilation. In recent years, there has been increasing evidence of better clinical outcomes following surgical stabilization of clavicle fractures in the setting of this combination of injuries. The aim of this study was to evaluate surgical versus non-surgical treatment of clavicle fractures in severe thoracic trauma in terms of clinical and radiological outcomes in order to make a generalized treatment recommendation based on the results of a large patient cohort.

PATIENTS AND METHODS

This retrospective study included 181 patients (42 women, 139 men) from a European level I trauma centre with a median of 49.3 years in between 2005 and 2021. In 116 cases, the clavicle fracture was stabilized with locking plate or hook plate fixation (group 1), and in 65 cases, it was treated non-surgically (group 2). Long-term functional outcomes at least one year postoperatively using the disabilities of the arm, shoulder and hand (DASH) questionnaire and the Nottingham Clavicle Score (NCS) as well as radiological outcomes were collected in addition to parameters such as hospital days, intensive care days, and complication rates.

RESULTS

The Injury Severity Score (ISS) was 17.8 ± 9.8 in group 1 and 19.9 ± 14.4 in group 2 (mean ± SEM; p = 0.93), the time in hospital was 21.5 ± 27.2 days in group 1 versus 16 ± 29.3 days in group 2 (p = 0.04). Forty-seven patients in group 1 and eleven patients in the group 2 were treated in the ICU. Regarding the duration of ventilation (group 1: 9.1 ± 8.9 days, group 2: 8.1 ± 7.7 days; p = 0.64), the functional outcome (DASH group 1: 11 ± 18 points, group 2: 13.7 ± 18. 4 points, p = 0.51; NCS group 1: 17.9 ± 8.1 points, group 2: 19.4 ± 10.3 points, p = 0.79) and the radiological results, no significant differences were found between the treatment groups. With an overall similar complication rate, pneumonia was found in 2% of patients in group 1 and in 14% of patients in group 2 (p = 0.001).

DISCUSSION

This study could demonstrate that surgical locking plate fixation of clavicle fractures in combination with CWI significantly reducing the development of posttraumatic pneumonia in a large patient collection and, therefore, can be recommended as standard therapeutic approach for severe thoracic trauma.

Association between BUN/creatinine ratio and the risk of in-hospital mortality in patients with trauma-related acute respiratory distress syndrome: a single-centre retrospective cohort from the MIMIC database

OBJECTIVE

Recent studies have shown that blood urea nitrogen to creatinine (BUN/Cr) ratio might be an effective marker for the prognosis of patients with respiratory diseases. Herein, we aimed to assess the association between BUN/Cr ratio and the risk of in-hospital mortality in patients with trauma-related acute respiratory distress syndrome (ARDS).

DESIGN

A retrospective cohort study.

SETTING AND PARTICIPANTS

1034 patients were extracted from the Medical Information Mart for Intensive Care-III (MIMIC-III) database.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcome of the study was in-hospital mortality, defined by the vital status at the time of hospital discharge (ie, survivors and non-survivors).

RESULTS

Of the total patients, 191 (18.5%) died in hospital. The median follow-up duration was 16.0 (8.3-26.6) days. The results showed that high level of BUN/Cr ratio was significantly associated with an increased risk of in-hospital mortality (15.54-21.43: HR=2.00, 95% CI: (1.18 to 3.38); >21.43: HR=1.76, 95% CI: (1.04 to 2.99)) of patients with trauma-related ARDS. In patients with trauma-related ARDS that aged ≥65 years old, male and female, Onychomycosis Severity Index (OSI)>98, Revised Trauma Score (RTS)>11, Simplified Acute Physiology Score II (SAPS-II)>37 and sequential organ failure assessment (SOFA) scores≤7, BUN/Cr ratio was also related to the increased risk of in-hospital mortality (all p<0.05). The predictive performance of BUN/Cr ratio for in-hospital mortality was superior to BUN or Cr, respectively, with the area under the curve of receiver operator characteristic curve at 0.6, and that association was observed in age, gender, OSI, RTS, SAPS-II and SOFA score subgroups.

CONCLUSION

BUN/Cr ratio may be a potential biomarker for the risk of in-hospital mortality of trauma-related ARDS, which may help the clinicians to identify high-risk individuals and to implement clinical interventions.

Potential Interaction Between Sepsis and Acute Respiratory Distress Syndrome and Effect on the 6-Month Clinical Outcomes: A Preliminary Secondary Analysis of a Prospective Observational Study

BACKGROUND

This study aimed to investigate the effect of the potential interaction between sepsis and acute respiratory distress syndrome (ARDS) on the 6-month clinical outcomes.

METHODS

This secondary analysis of a prospective multicenter observational study included patients who were expected to receive mechanical ventilation for more than 48 h. Patients were stratified based on the incidence of sepsis and further subdivided according to the presence of ARDS. The primary endpoints for patients whose follow-up information was available included mortality (n = 162) and the occurrence of PICS (n = 96) at six months. The diagnosis of PICS was based on any of the following criteria: (1) decrease ≥ 10 points in the physical component score of the 36-item Short Form (SF36) questionnaire; (2) decrease ≥ 10 points in the mental component score of the SF-36; or (3) decline in the Short Memory Questionnaire (SMQ) score and SMQ score < 40 at six months after ICU admission. We conducted multivariate logistic regression analyses to assess the effect of the potential interaction between ARDS and sepsis on the 6-month clinical outcomes.

RESULTS

The mortality in the ARDS sub-group was higher than that in the non-ARDS subgroup [47% (7/15) versus 21% (18/85)] in the non-sepsis group. However, the mortality in the ARDS and non-ARDS subgroups was similar in the sepsis group. Multivariate logistic regression analyses revealed that ARDS was significantly associated with mortality in the non-sepsis group (adjusted OR: 5.25; 95% CI: 1.45-19.09; p = .012), but not in the sepsis group (P for interaction = .087). Multivariate logistic regression analyses showed ARDS was not associated with PICS occurrence in the non-sepsis and sepsis groups (P-value for the interaction = .039).

CONCLUSIONS

This hypothesis-generating study suggested that the effect of ARDS on the 6-month outcomes depended on the presence or absence of sepsis.

TRIAL REGISTRATION

Not applicable.

The role of neutrophil extracellular traps in acute lung injury

Acute lung injury (ALI) is a heterogeneous inflammatory condition associated with high morbidity and mortality. Neutrophils play a key role in the development of different forms of ALI, and the release of neutrophil extracellular traps (NETs) is emerging as a common pathogenic mechanism. NETs are essential in controlling pathogens, and their defective release or increased degradation leads to a higher risk of infection. However, NETs also contain several pro-inflammatory and cytotoxic molecules than can exacerbate thromboinflammation and lung tissue injury. To reduce NET-mediated lung damage and inflammation, DNase is frequently used in preclinical models of ALI due to its capability of digesting NET DNA scaffold. Moreover, recent advances in neutrophil biology led to the development of selective NET inhibitors, which also appear to reduce ALI in experimental models. Here we provide an overview of the role of NETs in different forms of ALI discussing existing gaps in our knowledge and novel therapeutic approaches to modulate their impact on lung injury.

Influence of surgical stabilization of clavicle fractures in multiply-injured patients with thoracic trauma

Thoracic trauma has decisive influence on the outcome of multiply-injured patients and is often associated with clavicle fractures. The affected patients are prone to lung dysfunction and multiple organ failure. A multi-center, retrospective analysis of patient records documented in the TraumaRegister DGU was performed to assess the influence of surgical stabilization of clavicle fractures in patients with thoracic trauma. A total of 3,209 patients were included in the analysis. In 1362 patients (42%) the clavicle fracture was treated operatively after 7.1 ± 5.3 days. Surgically treated patients had a significant reduction in lung failure (p = 0.013, OR = 0.74), multiple organ failure (p = 0.001, OR = 0.64), intubation time (p = 0.004; -1.81 days) and length of hospital stay (p = 0.014; -1.51 days) compared to non-operative treatment. Moreover, surgical fixation of the clavicle within five days following hospital admission significantly reduced the rates of lung failure (p = 0.01, OR = 0.62), multiple organ failure (p = 0.01, OR = 0.59) and length of hospital stay (p = 0.01; -2.1 days). Based on our results, multiply-injured patients with thoracic trauma and concomitant clavicle fracture may benefit significantly from surgical stabilization of a clavicle fracture, especially when surgery is performed within the first five days after hospital admission.

Prognostic factors for development of acute respiratory distress syndrome following traumatic injury - a systematic review and meta-analysis

PURPOSE

To summarise the prognostic associations between various clinical risk factors and the development of the acute respiratory distress syndrome (ARDS) following traumatic injury.

METHODS

We conducted this review in accordance with the PRISMA and CHARMS guidelines. We searched six databases from inception through December 2020. We included English language studies describing the clinical risk factors associated with the development of post-traumatic ARDS, as defined by either the American-European Consensus Conference or the Berlin definition. We pooled adjusted odds ratios for prognostic factors using the random effects method. We assessed risk of bias using the QUIPS tool and certainty of findings using GRADE methodology.

RESULTS

We included 39 studies involving 5 350 927 patients. We identified the amount of crystalloid resuscitation as a potentially modifiable prognostic factor associated with the development of post-traumatic ARDS (adjusted odds ratio [aOR] 1.19 for each additional liter of crystalloid administered within first 6 h after injury, 95% CI 1.15 to 1.24, high certainty). Non-modifiable prognostic factors with a moderate or high certainty of association with post-traumatic ARDS included increasing age, non-Hispanic white race, blunt mechanism of injury, presence of head injury, pulmonary contusion, or rib fracture; and increasing chest injury severity.

CONCLUSION

We identified one important modifiable factor, the amount of crystalloid resuscitation within the first 24 h of injury, and several non-modifiable factors associated with development of post-traumatic ARDS. This information should support the judicious use of crystalloid resuscitation in trauma patients and may inform the development of a risk-stratification tools.

The Cost of ARDS: A Systematic Review

BACKGROUND

ARDS is an inflammatory condition of the lungs and is a common condition in adult ICUs. The resources required and costs of care for patients with ARDS are significant because of the severity of the illness and extended ICU lengths of stay.

RESEARCH QUESTION

What are the costs associated with ARDS?

STUDY DESIGN AND METHODS

We systematically searched the literature through April 29, 2021, for articles relevant to ARDS and costs. MEDLINE, Embase, Central, and EconLit databases were searched, and articles that reported on cost data from an original publication in adult patients with ARDS were included. Two authors independently assessed articles for inclusion and extracted data elements related to costs, methodology, health-care system type, economic perspective, and clinical data. Publication quality was assessed using a modified version of the Quality of Health Economic Studies Instrument.

RESULTS

Four thousand six hundred sixty-three publications were found, of which 110 were included for full-text review (κ = 0.72). A total of 22 publications (49,483 patients) were suitable for data extraction. The publications represented a broad range of health-care systems, economic perspectives, costing methodology, and time frames. Mean inpatient costs ranged from $8,476 (2021 US dollars [USD]) to $547,974 (2021 USD) and were highest in publications of lower quality and in American health systems and were associated with trauma cohorts. Outpatient costs were highest in publications with higher readmission rates, longer durations of follow-up, and in American health systems.

INTERPRETATION

A wide range of costing data is available for ARDS. A comprehensive synthesis of this literature frames the reasons for this and allows estimates to reflect the context in which they were assessed. This information will be of value to researchers and administrators interested in the economics of caring for patients with ARDS.

TRIAL REGISTRY

PROSPERO; No.: CRD42020192487.

Acute Respiratory Distress Syndrome (ARDS) after trauma: Improving incidence, but increasing mortality

PURPOSE

Acute Respiratory Distress Syndrome (ARDS) is an infrequent, yet morbid inflammatory complication in injury victims. With the current project we sought to estimate trends in incidence, determine outcomes, and identify risk factors for ARDS and related mortality.

MATERIALS & METHODS

The national Trauma Quality Improvement Program dataset (2010-2014) was queried. Demographics, injury characteristics and outcomes were compared between patients who developed ARDS and those who did not. Logistic regression models were fitted for the development of ARDS and mortality respectively, adjusting for relevant confounders.

RESULTS

In the studied 808,195 TQIP patients, incidence of ARDS decreased over the study years (3-1.1%, p < 0.001), but related mortality increased (18.-21%, p = 0.001). ARDS patients spent an additional 14.7 ± 10.3 days in the hospital, 9.7 ± 7.9 in the ICU, and 6.6 ± 9.4 on mechanical ventilation (all p < 0.001). Older age, male gender, African American race increased risk for ARDS. Age, male gender, lower GCS and higher ISS also increased mortality risk among ARDS patients. Several pre-existing comorbidities including chronic alcohol use, diabetes, smoking, and respiratory disease also increased risk.

CONCLUSION

Although the incidence of ARDS after trauma appears to be declining, mortality is on the rise.

Attributable mortality of acute respiratory distress syndrome: a systematic review, meta-analysis and survival analysis using targeted minimum loss-based estimation

BACKGROUND

Although acute respiratory distress syndrome (ARDS) is associated with high mortality, its direct causal link with death is unclear. Clarifying this link is important to justify costly research on prevention of ARDS.

OBJECTIVE

To estimate the attributable mortality, if any, of ARDS.

DESIGN

First, we performed a systematic review and meta-analysis of observational studies reporting mortality of critically ill patients with and without ARDS matched for underlying risk factor. Next, we conducted a survival analysis of prospectively collected patient-level data from subjects enrolled in three intensive care unit (ICU) cohorts to estimate the attributable mortality of critically ill septic patients with and without ARDS using a novel causal inference method.

RESULTS

In the meta-analysis, 44 studies (47 cohorts) involving 56 081 critically ill patients were included. Mortality was higher in patients with versus without ARDS (risk ratio 2.48, 95% CI 1.86 to 3.30; p<0.001) with a numerically stronger association between ARDS and mortality in trauma than sepsis. In the survival analysis of three ICU cohorts enrolling 1203 critically ill patients, 658 septic patients were included. After controlling for confounders, ARDS was found to increase the mortality rate by 15% (95% CI 3% to 26%; p=0.015). Significant increases in mortality were seen for severe (23%, 95% CI 3% to 44%; p=0.028) and moderate (16%, 95% CI 2% to 31%; p=0.031), but not for mild ARDS.

CONCLUSIONS

ARDS has a direct causal link with mortality. Our findings provide information about the extent to which continued funding of ARDS prevention trials has potential to impart survival benefit.

PROSPERO REGISTRATION NUMBER

CRD42017078313.

Primary Blast Lung Injury: The UK Military Experience

INTRODUCTION

Primary blast lung injury occurs when an explosive shock wave passes through the thorax and transits through tissues of varying densities. It requires close proximity to an explosion and presents quick with respiratory distress in survivors.

MATERIALS AND METHODS

The Joint Theatre Trauma Registry and the Defence Statistics (Health) Database were interrogated for casualties injured as a result of an explosion during the conflict in Afghanistan. The case notes and imaging of casualties meeting the criteria for diagnosis were reviewed. Demographic and clinical data on casualties with primary blast lung injury were analyzed.

RESULTS

848 blast-exposed casualties survived to discharge from intensive care, and 238 blast-exposed casualties were killed in action. Following exclusions, 111 case notes and all postmortem reports were reviewed in detail. About, 25 casualties had isolated primary blast lung injury (2.9% of casualties surviving to discharge from intensive care) and 31 nonsurvivors (13% of nonsurvivors) had the disease documented at postmortem. Severe cases of primary blast lung injury required an estimated average of 4.5 days of conventional mechanical ventilation.

CONCLUSIONS

8.1% of blast exposed casualties suffered primary blast lung injury. It was a less severe disease than other nontraumatic forms of acute lung injury and did not cause deaths once a casualty had reached a combat support hospital. It was well managed with a relatively brief period of conventional mechanical ventilation.

Living on Borrowed Breath: Respiratory Distress, Social Breathing, and the Vital Movement of Ventilators

Based on ethnographic research in a public hospital trauma intensive care unit in Mumbai, India, this article formulates the concept of "social breathing" to analyze how breath is central to values of life at the edges of death. Case studies of emergency resuscitation, intubation, and ventilation each illustrate breathing's sociality, as people and machines move air both materially and immaterially. Amid the hospital's rationing of life support technologies, forms of life that seem to be self-regulated are better understood as relational movements of breath. Social breathing stands to reshape our understanding of the biopolitics of intensive care by drawing attention to uncertain techniques of the body. These techniques move at the hinge between person and environment, self and other, public and private health care systems, and medicine and machine. Life's valuation at this hinge takes shape through breath moving against its limits. Ultimately, the article argues that it is crucial to understand how ventilators mediate the edges of life and death by tracing the circulations of life support as the movements of life itself. As patients, families, and hospital workers struggle to make and manage breath, we might better grapple with the social relations that emerge as life support shapes life.

Predictors and outcomes of acute respiratory failure in hospitalised patients with acute pancreatitis

BACKGROUND AND AIM

Acute pancreatitis (AP) is associated with organ failures and systemic complications, most commonly acute respiratory failure (ARF) and acute kidney injury. So far, no studies have analysed the predictors and hospitalisation outcomes, of patients with AP who developed ARF. The aim of this study was to measure the prevalence of ARF in AP and to determine the clinical predictors for ARF and mortality in AP.

METHODS

This is a retrospective cohort study using the Nationwide Inpatient Sample database from the year 2005-2014. The study population consisted of all hospitalisations with a primary or secondary discharge diagnosis of AP, which is further stratified based on the presence of ARF. The outcome measures include in-hospital mortality, hospital length of stay and hospitalisation cost.

RESULTS

In our study, about 5.4% of patients with AP had a codiagnosis of ARF, with a mortality rate of 26.5%. The significant predictors for ARF include sepsis, pleural effusion, pneumonia and cardiogenic shock. Key variables that were associated with a higher risk of mortality include mechanical ventilation, age more than 65 years, sepsis and cancer (excluding pancreatic cancer). The presence of ARF increased hospital stay by 8.3 days and hospitalisation charges by US$103 460.

CONCLUSION

In this study, we demonstrate that ARF is a significant risk factor for increased hospital mortality, greater length of stay and higher hospitalisation charges in patients with AP. This underlines significantly higher resource utilisation in patients with a dual diagnosis of AP-ARF.

Acute respiratory distress syndrome-attributable mortality in critically ill patients with sepsis

PURPOSE

Previous studies assessing impact of acute respiratory distress syndrome (ARDS) on mortality have shown conflicting results. We sought to assess the independent association of ARDS with in-hospital mortality among intensive care unit (ICU) patients with sepsis.

METHODS

We studied two prospective sepsis cohorts drawn from the Early Assessment of Renal and Lung Injury (EARLI; n = 474) and Validating Acute Lung Injury markers for Diagnosis (VALID; n = 337) cohorts. ARDS was defined by Berlin criteria. We used logistic regression to compare in-hospital mortality in patients with and without ARDS, controlling for baseline severity of illness. We also estimated attributable mortality, adjusted for illness severity by stratification.

RESULTS

ARDS occurred in 195 EARLI patients (41%) and 99 VALID patients (29%). ARDS was independently associated with risk of hospital death in multivariate analysis, even after controlling for severity of illness, as measured by APACHE II (odds ratio [OR] 1.65 (95% confidence interval [CI] 1.02, 2.67), p = 0.04 in EARLI; OR 2.12 (CI 1.16, 3.92), p = 0.02 in VALID). Patients with severe ARDS (P/F < 100) primarily drove this relationship. The attributable mortality of ARDS was 27% (CI 14%, 37%) in EARLI and 37% (CI 10%, 51%) in VALID. ARDS was independently associated with ICU mortality, hospital length of stay (LOS), ICU LOS, and ventilator-free days.

CONCLUSIONS

Development of ARDS among ICU patients with sepsis confers increased risk of ICU and in-hospital mortality in addition to other important outcomes. Clinical trials targeting patients with severe ARDS will be best poised to detect measurable differences in these outcomes.

Association between age and acute respiratory distress syndrome development and mortality following trauma

BACKGROUND

Improved understanding of the relationship between patient age and acute respiratory distress syndrome (ARDS) development and mortality following traumatic injury may help facilitate generation of new hypotheses about ARDS pathophysiology and the role of novel treatments to improve outcomes across the age spectrum.

METHODS

We conducted a retrospective cohort study of trauma patients included in the National Trauma Data Bank who were admitted to an intensive care unit from 2007 to 2016. We determined ARDS incidence and mortality across eight age groups for the entire 10-year study period and by year. We used generalized linear Poisson regression models adjusted for underlying mortality risk (injury mechanism, Injury Severity Score, admission Glasgow Coma Scale score, admission heart rate, and admission hypotension).

RESULTS

Acute respiratory distress syndrome occurred in 3.1% of 1,297,190 trauma encounters. Acute respiratory distress syndrome incidence was lowest among pediatric patients and highest among adults aged 35 to 64 years. Acute respiratory distress syndrome mortality was highest among patients 80 years or older (43.9%), followed by 65 to 79 years (30.6%) and 4 years or younger (25.3%). The relative risk of mortality associated with ARDS was highest among the pediatric age groups, with an adjusted relative risk (aRR) of 2.06 (95% confidence interval [CI], 1.72-2.70) among patients 4 years or younger compared with an aRR of 1.51 (95% CI, 1.42-1.62) for the entire cohort. Acute respiratory distress syndrome mortality increased over the 10-year study period (aRR, 1.03 per year; 95% CI, 1.02-1.05 per year), whereas all-cause mortality decreased (aRR, 0.98 per year; 95% CI, 0.98-0.99 per year).

CONCLUSIONS

While ARDS development following traumatic injury was most common in middle-aged adults, patients 4 years or younger and 65 years or older with ARDS experienced the highest burden of mortality. Children 4 years or younger were disproportionately affected by ARDS relative to their low underlying mortality following trauma that was not complicated by ARDS. Acute respiratory distress syndrome-associated mortality following trauma has worsened over the past decade, emphasizing the need for new prevention and treatment strategies.

LEVEL OF EVIDENCE

Prognostic/epidemiological study, level III.

Aggressive treatment of acute kidney injury and hyperkalemia improves survival in a combat relevant trauma model in swine

INTRODUCTION

Our swine model of pulmonary contusion (PC) and hemorrhagic shock (HS) was initially complicated by renal failure, hyperkalemia, and premature death. To study the effects of novel therapies on organ failure, improved survival was necessary requiring the design of an aggressive treatment regimen.

METHODS

Anesthetized swine sustained either PC or PC with grade V liver injury to induce HS (PC + HS). After injury, animals were resuscitated followed by either standard care (SC) with maintenance intravenous fluids (IVF) and treatment at potassium level of 6.0 mmol/L (n = 7; 3 PC, 4 PC + HS) or aggressive care (AC) with increased initial IVF, early and frequent potassium monitoring, and treatment at potassium level of 5.0 mmol/L (n = 15, 8 PC, 7 PC + HS). Hyperkalemia was treated with calcium, insulin, and glucose in both groups.

RESULTS

Survival to 48 h was achieved in 13/15 (87%) in the AC group and 2/7 (29%) in the SC group (p = 0.014). Compared to SC, AC improved median survival (48 vs. 18 h, p = 0.008) and lowered potassium (5.0 vs. 7.5 mmol/L), creatinine (2.4 vs. 4.0 mg/dL), BUN (27.5 vs. 39.0 mg/dL), and lactate (0.97 vs. 3.57 mmol/L) at the last observed time-point prior to death. For PC + HS animals, survival to 48 h was achieved in 6/7 in the AC group and 0/4 in the SC group with an improved median survival in the AC group (48 vs. 18 h, p = 0.011) DISCUSSION: Aggressive and early hyperkalemia treatment prolongs survival while reducing kidney injury and potassium levels in a combat relevant injury model in swine.

Clinical Characteristics, Major Morbidity, and Mortality in Trauma-Related Pediatric Acute Respiratory Distress Syndrome

OBJECTIVES

To determine the presence, central characteristics, and impact on major morbidity and mortality of trauma-related pediatric acute respiratory distress syndrome.

DESIGN

Retrospective review of a prospective trauma database.

SETTING

American College of Surgeons verified level 1 trauma center in an urban setting.

PATIENTS

Trauma patients age 0 to 18 years old inclusive.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Of the 7,382 patients presenting within the 10-year study period, 646 met study criteria for inclusion in the analysis. Trauma-related pediatric acute respiratory distress syndrome was present in 9% of the analyzed cohort. On univariate analysis and compared with those without, trauma-related pediatric acute respiratory distress syndrome occurred more commonly among those with traumatic brain injury (77.2% vs 45.5%; p < 0.001), non-accidental trauma (28.8% vs 10.2%; p < 0.001), and an injury severity score greater than 30 (27.1% vs 3.8%; p 0.001). New or progressive multiple organ dysfunction syndrome was significantly higher in trauma-related pediatric acute respiratory distress syndrome patients (86.7% vs 10.4%; p < 0.001) as was mortality (18.3% vs 3.1%; p < 0.001) than in those without. The presence of trauma-related pediatric acute respiratory distress syndrome (odds ratio, 6.98; 95% CI, 2.95-16.5; p < 0.001), younger age (odds ratio, 0.93; 95% CI, 0.87-0.99; p = 0.038), and worse injury severity (odds ratio, 1.19; 95% CI, 1.14-1.24; p < 0.001) were all independent statistical predictors of new or progressive multiple organ dysfunction syndrome in this retrospective cohort. Mortality in patients without trauma-related pediatric acute respiratory distress syndrome increased with increasing injury severity, whereas mortality in patients with trauma-related pediatric acute respiratory distress syndrome was the same regardless of injury severity. On multivariable regression analysis, while age and injury severity were independent statistical predictors of mortality, trauma-related pediatric acute respiratory distress syndrome was not (odds ratio, 2.35; 95% CI, 0.88-6.28; p = 0.087).

CONCLUSIONS

Pediatric acute respiratory distress syndrome is present in the pediatric trauma population. Trauma-related pediatric acute respiratory distress syndrome is associated with eight times the organ dysfunction and five times the mortality compared with patients without trauma-related pediatric acute respiratory distress syndrome, yet research in this area is lacking. Further prospective, mechanistic evaluations are essential to understand why these patients are at risk and how to effectively intervene to improve outcomes.

Morbidity and Mortality Among Critically Injured Children With Acute Respiratory Distress Syndrome

OBJECTIVES

To evaluate morbidity and mortality among critically injured children with acute respiratory distress syndrome.

DESIGN

Retrospective cohort study.

SETTING

Four-hundred sixty Level I/II adult or pediatric trauma centers contributing to the National Trauma Data Bank.

PATIENTS

One hundred forty-six thousand fifty-eight patients less than 18 years old admitted to an ICU with traumatic injury from 2007 to 2016.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We assessed in-hospital mortality and need for postdischarge care among patients with and without acute respiratory distress syndrome and hospital resource utilization and discharge disposition among survivors. Analyses were adjusted for underlying mortality risk (age, Injury Severity Score, serious brain or chest injury, and admission heart rate and hypotension) and year, transfer status, and facility trauma level designation. Acute respiratory distress syndrome occurred in 2,590 patients (1.8%). Mortality was 20.0% among acute respiratory distress syndrome patients versus 4.3% among nonacute respiratory distress syndrome patients, with an adjusted relative risk of 1.76 (95% CI, 1.52-2.04). Postdischarge care was required in an additional 44.8% of acute respiratory distress syndrome patients versus 16.0% of patients without acute respiratory distress syndrome (adjusted relative risk, 3.59; 2.87-4.49), with only 35.1% of acute respiratory distress syndrome patients discharging to home versus 79.8% of patients without acute respiratory distress syndrome. Acute respiratory distress syndrome mortality did not change over the 10-year study period (adjusted relative risk, 1.01/yr; 0.96-1.06) nor did the proportion of acute respiratory distress syndrome patients requiring postdischarge care (adjusted relative risk, 1.04/yr; 0.97-1.11). Duration of ventilation, ICU stay, and hospital stay were all significantly longer among acute respiratory distress syndrome survivors. Tracheostomy placement occurred in 18.4% of acute respiratory distress syndrome survivors versus 2.1% of patients without acute respiratory distress syndrome (adjusted relative risk, 3.10; 2.59-3.70).

CONCLUSIONS

Acute respiratory distress syndrome development following traumatic injury in children is associated with significantly increased risk of morbidity and mortality, even after adjustment for injury severity and hemodynamic abnormalities. Outcomes have not improved over the past decade, emphasizing the need for new therapeutic interventions, and prevention strategies for acute respiratory distress syndrome among severely injured children.

Acute Respiratory Distress Syndrome: Etiology, Pathogenesis, and Summary on Management

The acute respiratory distress syndrome (ARDS) has multiple causes and is characterized by acute lung inflammation and increased pulmonary vascular permeability, leading to hypoxemic respiratory failure and bilateral pulmonary radiographic opacities. The acute respiratory distress syndrome is associated with substantial morbidity and mortality, and effective treatment strategies are limited. This review presents the current state of the literature regarding the etiology, pathogenesis, and management strategies for ARDS.

Acute Respiratory Failure

Acute respiratory distress syndrome (ARDS) is a condition affecting critically ill patients, characterized by pulmonary inflammation and defects in oxygenation due to either direct or indirect injury to the lungs. These guidelines will define the diagnosis and management of ARDS, particularly among combat casualties and patients in the deployed environment. The cornerstone of management of ARDS involves maintaining adequate oxygenation while avoiding further pulmonary injury through lung-protective ventilation. Additional strategies for advanced respiratory failure, such as prone positioning, neuromuscular blockade, and extracorporeal membrane oxygenation will be reviewed here as well. Particularly important to the care of the patient with ARDS in the deployed environment is a familiarity with the challenges and indications for transport/aeromedical evacuation.

Nationwide cohort study of independent risk factors for acute respiratory distress syndrome after trauma

Background

The primary objective of this study was to evaluate the effect of specific direct and indirect factors that accounted, in trauma patients, for the development of acute respiratory distress syndrome (ARDS) and mortality in patients with ARDS.

Methods

We performed a retrospective cohort study of patients from the National Trauma Data Bank. Multilevel mixed-effects logistic regression was used with the development of ARDS as the primary and mortality in patients with ARDS as the secondary outcome measures. We compared trauma patients with versus without thoracic (direct) and extrathoracic (indirect) risk factors, using patient demographics, physiologic, and anatomic injury severity as covariates. Subset analysis was performed for patients with trauma-induced lung contusion (TILC) and for patients with minor (Injury Severity Score [ISS] ≤15) injury.

Results

A total of 2 998 964 patients were studied, of whom 28 597 developed ARDS. From 2011 to 2014, the incidence of ARDS decreased; however, mortality in patients with ARDS has increased. Predictors of ARDS included direct thoracic injury (TILC, multiple rib fractures, and flail chest), as well as indirect factors (increased age, male gender, higher ISS, lower Glasgow Coma Scale motor component score, history of cardiopulmonary or hematologic disease, and history of alcoholism or obesity). Patients with ARDS secondary to direct thoracic injury had a lower risk of mortality compared with patients with ARDS due to other mechanisms.

Discussion

Despite the decreasing incidence of trauma-induced ARDS, mortality in patients with ARDS has increased. Direct thoracic injury was the strongest predictor of ARDS. Knowing specific contributors to trauma-induced ARDS could help identify at-risk patients early in their hospitalization and mitigate the progression to ARDS and thereby mortality.

Level of evidence

Prognostic study, level III.

Does lack of thoracic trauma attenuate the severity of pulmonary failure? An 8-year analysis of critically injured patients

PURPOSE

Patients with thoracic trauma are presumed to be at higher risk for pulmonary dysfunction, but adult respiratory distress syndrome (ARDS) may develop in any patient, regardless of associated chest injury. This study evaluated the impact of thoracic trauma and pulmonary failure on outcomes in trauma patients admitted to the intensive-care unit (ICU).

METHODS

All trauma patients admitted to the ICU over an 8-year period were identified. Patients that died within 48 h of arrival were excluded. Patients were stratified by baseline characteristics, injury severity, development of ARDS, and infectious complications. Multiple logistic regression was used to determine variables significantly associated with the development of ARDS.

RESULTS

10,362 patients were identified. After exclusions, 4898 (50%) patients had chest injury and 4975 (50%) did not. 200 (2%) patients developed ARDS (3.6% of patients with chest injury and 0.5% of patients without chest injury). Patients with ARDS were more likely to have chest injury than those without ARDS (87% vs 49%, p < 0.001). However, of the patients without chest injury, the development of ARDS still led to a significant increase in mortality compared to those patients without ARDS (58% vs 5%, p < 0.001). Multiple logistic regression found ventilator-associated pneumonia (VAP) to be the only independent predictor for the development of ARDS in ICU patients without chest injury.

CONCLUSIONS

ARDS development was more common in patients with thoracic trauma. Nevertheless, the development of ARDS in patients without chest injury was associated with a tenfold higher risk of death. The presence of VAP was found to be the only potentially preventable and treatable risk factor for the development of ARDS in ICU patients without chest injury.

Molecular Characterization of Hypoxic Alveolar Epithelial Cells After Lung Contusion Indicates an Important Role for HIF-1α

OBJECTIVE

To understand the fate and regulation of hypoxic type II alveolar epithelial cells (AECs) after lung contusion (LC).

BACKGROUND

LC due to thoracic trauma is a major risk factor for the development of acute respiratory distress syndrome. AECs have recently been implicated as a primary driver of inflammation in LC. The main pathological consequence of LC is hypoxia, and a key mediator of adaptation to hypoxia is hypoxia-inducible factor (HIF)-1. We have recently published that HIF-1α is a major driver of acute inflammation after LC through type II AEC.

METHODS

LC was induced in wild-type mice (C57BL/6), luciferase-based hypoxia reporter mice (ODD-Luc), and HIF-1α conditional knockout mice. The degree of hypoxia was assessed using hypoxyprobe and in vivo imaging system. The fate of hypoxic AEC was evaluated by luciferase dual staining with caspases-3 and Ki-67, terminal deoxynucleotidyl transferase dUTP nick end labeling, and flow cytometry with ApoStat. NLRP-3 expression was determined by western blot. Laser capture microdissection was used to isolate AECs in vivo, and collected RNA was analyzed by Q-PCR for HIF-related pathways.

RESULTS

Global hypoxia was present after LC, but hypoxic foci were not uniform. Hypoxic AECs preferentially undergo apoptosis. There were significant reductions in NLRP-3 in HIF-1α conditional knockout mice. The expression of proteins involved in HIF-related pathways and inflammasome activation were significantly increased in hypoxic AECs.

CONCLUSIONS

These are the first in vivo data to identify, isolate, and characterize hypoxic AECs. HIF-1α regulation through hypoxic AECs is critical to the initiation of acute inflammation after LC.

Magnoflorine Ameliorates Lipopolysaccharide-Induced Acute Lung Injury via Suppressing NF-κB and MAPK Activation

Acute lung injury (ALI) which is featured by a strong pulmonary inflammation, is a major cause of morbidity and mortality in critically ill patients. Magnoflorine, a quaternary alkaloid isolated from Chinese herb Magnolia or Aristolochia, has been reported to have potent anti-inflammatory properties. However, the effect of magnoflorine on lipopolysaccharide (LPS)-induced ALI in mice has not been reported. The purpose of the present study is to investigate the anti-inflammatory effect of magnoflorine on LPS-induced ALI and elucidate its possible molecular mechanisms in RAW264.7 cells. The results of histopathological changes as well as the myeloperoxidase (MPO) activity indicated that magnoflorine significantly alleviated the lung injury induced by LPS. In addition, qPCR results showed that magnoflorine dose-dependently decreased the expression of pro-inflammatory cytokines TNF-α, IL-1β, and IL-6. Immunofluorescence assay also confirmed that the level of Toll-like receptor 4 (TLR4) induced by LPS was inhibited by magnoflorine treatment. Further experiments were performed using Western blotting to detect the expression of related proteins in the NF-κB and MAPK signaling pathways. The results showed that magnoflorine suppressed the levels of phosphorylated p65, IκBα, p38, ERK, and JNK. In conclusion, all data indicate that magnoflorine could protect against LPS-induced inflammation in ALI at least partially by inhibiting TLR4-mediated NF-κB and MAPK signaling pathways.

Neutrophils in Tissue Trauma of the Skin, Bone, and Lung: Two Sides of the Same Coin

Following severe tissue injury, patients are exposed to various danger- and microbe-associated molecular patterns, which provoke a strong activation of the neutrophil defense system. Neutrophils trigger and modulate the initial posttraumatic inflammatory response and contribute critically to subsequent repair processes. However, severe trauma can affect central neutrophil functions, including circulation half-life, chemokinesis, phagocytosis, cytokine release, and respiratory burst. Alterations in neutrophil biology may contribute to trauma-associated complications, including immune suppression, sepsis, multiorgan dysfunction, and disturbed tissue regeneration. Furthermore, there is evidence that neutrophil actions depend on the quality of the initial stimulus, including trauma localization and severity, the micromilieu in the affected tissue, and the patient's overall inflammatory status. In the present review, we describe the effects of severe trauma on the neutrophil phenotype and dysfunction and the consequences for tissue repair. We particularly concentrate on the role of neutrophils in wound healing, lung injury, and bone fractures, because these are the most frequently affected tissues in severely injured patients.

Gastric Aspiration and Its Role in Airway Inflammation

Gastro-Oesophageal Reflux (GOR) has been associated with chronic airway diseases while the passage of foreign matter into airways and lungs through aspiration has the potential to initiate a wide spectrum of pulmonary disorders. The clinical syndrome resulting from such aspiration will depend both on the quantity and nature of the aspirate as well as the individual host response. Aspiration of gastric fluids may cause damage to airway epithelium, not only because acidity is toxic to bronchial epithelial cells but also due to the effect of digestive enzymes such as pepsin and bile salts. Experimental models have shown that direct instillation of these factors to airways epithelia cause damage with a consequential inflammatory response. The pathophysiology of these responses is gradually being dissected, with better understanding of acute gastric aspiration injury, a major cause of acute lung injury, providing opportunities for therapeutic intervention and potentially, ultimately, improved understanding of the chronic airway response to aspiration. Ultimately, clarification of the inflammatory pathways which are related to micro-aspiration via pepsin and bile acid salts may eventually progress to pharmacological intervention and surgical studies to assess the clinical benefits of such therapies in driving symptom improvement or reducing disease progression.

Thoracic trauma severity contributes to differences in intensive care therapy and mortality of severely injured patients: analysis based on the TraumaRegister DGU®

Background

Thoracic trauma is a relevant source of comorbidity throughout multiply-injured patient care. We aim to determine a measurable influence of chest trauma’s severity on early resuscitation, intensive care therapy, and mortality in severely injured patients.

Methods

Patients documented between 2002 and 2012 in the TraumaRegister DGU®, aged ≥ 16 years, injury severity score (ISS) ≥ 16 are analyzed. Isolated brain injury and severe head injury led to exclusion. Subgroups are formed using the Abbreviated Injury Scale_Thorax.

Results

Twenty-two thousand five hundred sixty-five patients were predominantly male (74%) with mean age of 45.7 years (SD 19.3), blunt trauma (95%), mean ISS 25.6 (SD 9.6). Overall mean intubation period was 5.6 days (SD 10.7). Surviving patients were discharged from the ICU after a mean of about 5 days following extubation. Thoracic trauma severity (AIS_Thorax ≥ 4) and fractures to the thoracic cage significantly prolonged the ventilation period. Additionally, fractures extended the ICU stay significantly. Suffering from more than one thoracic injury was associated with a mean of 1–2 days longer intubation period and longer ICU stay. Highest rates of sepsis, respiratory, and multiple organ failure occurred in patients with critical compared to lesser thoracic trauma severity.

Conclusion

Thoracic trauma severity in multiply-injured patients has a measurable impact on rates of respiratory and multiple organ failure, sepsis, mortality, time of mechanical ventilation, and ICU stay.

Fifty Years of Research in ARDS. The Epidemiology of Acute Respiratory Distress Syndrome. A 50th Birthday Review

Since its first description 50 years ago, no other intensive care syndrome has been as extensively studied as acute respiratory distress syndrome (ARDS). Despite this extensive body of research, many basic epidemiologic questions remain unsolved. The lack of gold standard tests jeopardizes accurate diagnosis and translational research. Wide variation in the population incidence has been reported, making even simple estimates of the burden of disease problematic. Despite these limitations, there has been an increase in the understanding of pathophysiology and important risk factors both for the development of ARDS and for important patient-centered outcomes like mortality. In this Critical Care Perspective, we discuss the historical context of ARDS description and attempts at its definition. We highlight the epidemiologic challenges of studying ARDS, as well as other intensive care syndromes, and propose solutions to address them. We update the current knowledge of ARDS trends in incidence and mortality, risk factors, and recently described endotypes.

Investigating Cyclooxygenase Inhibition in a Rat Pulmonary Contusion Model: A Laboratory Study Finding No Improvement with Ibuprofen

Minimal advances have been made in the management of pulmonary contusions (PCs). The purpose of this study was to evaluate the impact of cyclooxygenase inhibition on outcomes following PC in a rat model. PC was induced in anesthetized adult rats. Ibuprofen was given to the treatment group (TG) and water was given to the control group (CG). Lung injury was assessed with pulse oximetry, arterial blood gases, CT, and histopathologic examination. Inflammation was measured with both serum and bronchoalveolar lavage (BAL) levels of tumor necrosis factor a and interleukin-6. Rats in the TG did not differ from rats in the CG with respect to oxygenation. Pathologic examination demonstrated a trend toward more inflammatory infiltrate in the CG, yet the sizes of the contusions were larger in the TG. The CG trended toward decreased levels of interleukin-6 in the serum and BAL at both three and seven days. While BAL levels of tumor necrosis factor a were increased in the TG at three days compared to the CG, they trended toward a reduced amount at seven days. Our data do not support cyclooxygenase inhibition for treatment to decrease the respiratory compromise associated with PC in this model of rat PCs.

Effect of ARDS Severity and Etiology on Short-Term Outcomes

BACKGROUND

We evaluated the outcome of subjects with ARDS in relation to etiology and severity in a retrospective cohort study of the ARDS Network randomized controlled trials. The primary outcome was 28-d mortality. The secondary outcomes were 60-d mortality and ventilator- and ICU-free days. For severity of ARDS, subjects were stratified according to P_aO2/F_IO2. The etiology of ARDS was classified into sepsis, pneumonia, aspiration, trauma, and others.

RESULTS

A total of 2,914 subjects were included in these trials. Outcomes were modeled with multivariable regressions adjusted for baseline covariates, age, sex, race, Acute Physiology and Chronic Health Evaluation III (APACHE III), vasopressor use, modified lung injury score, diabetes mellitus, cancer status, body mass index, pre-ICU location, ICU location, and study. There was no statistically significant difference in 28-d mortality in relation to ARDS severity. Subjects with trauma, compared with other etiologies of ARDS, had significantly lower mortality at 28 d (odds ratio [OR] = 0.47, 95% CI 0.26-0.83, P = .01). Sixty-day mortality was significantly lower for trauma subjects and those with severe ARDS group (OR = 0.5, 95% CI 0.3-0.85, P = .01 and OR = 0.71, 95% CI 0.52-0.98, P = .034, respectively). There were statistically significantly more ICU-free days and ventilator-free days for the aspiration group (OR = 1.09, 95% CI 1.02-1.17, P = .01 and OR = 1.09, 95% CI 1.02-1.16, P = .01, respectively). There was no statistically significant difference in ICU-free days or ventilator-free days in relation to severity of ARDS.

CONCLUSIONS

Severity of ARDS based on P_aO2/F_IO2 did not impact 28-d mortality, ventilator-free days, or ICU-free days. Among the etiologies of ARDS, trauma subjects had the lowest 28- and 60-d mortality, whereas subjects with aspiration had more ICU-free days and ventilator-free days.

Incidence, risk factors, and mortality associated with acute respiratory distress syndrome in combat casualty care

BACKGROUND

The overall incidence and mortality of acute respiratory distress syndrome (ARDS) in civilian trauma settings have decreased over the past four decades; however, the epidemiology and impact of ARDS on modern combat casualty care are unknown. We sought to determine the incidence, risk factors, resource utilization, and mortality associated with ARDS in current combat casualty care.

METHODS

This was a retrospective review of mechanically ventilated US combat casualties within the Department of Defense Trauma Registry (formerly the Joint Theater Trauma Registry) during Operation Iraqi Freedom/Enduring Freedom (October 2001 to August 2008) for ARDS development, resource utilization, and mortality.

RESULTS

Of 18,329 US Department of Defense Trauma Registry encounters, 4,679 (25.5%) required mechanical ventilation; ARDS was identified in 156 encounters (3.3%). On multivariate logistic regression, ARDS was independently associated with female sex (odds ratio [OR], 2.62; 95% confidence interval [CI], 1.21-5.71; p = 0.02), higher military-specific Injury Severity Score (Mil ISS) (OR, 4.18; 95% CI, 2.61-6.71; p < 0.001 for Mil ISS ≥25 vs. <15), hypotension (admission systolic blood pressure <90 vs. ≥90 mm Hg; OR, 1.76; 95% CI, 1.07-2.88; p = 0.03), and tachycardia (admission heart rate ≥90 vs. <90 beats per minute; OR, 1.53; 95% CI, 1.06-2.22; p = 0.02). Explosion injury was not associated with increased risk of ARDS. Critical care resource utilization was significantly higher in ARDS patients as was all-cause hospital mortality (ARDS vs. no ARDS, 12.8% vs. 5.9%; p = 0.002). After adjustment for age, sex, injury severity, injury mechanism, Mil ISS, hypotension, tachycardia, and admission Glasgow Coma Scale score, ARDS remained an independent risk factor for death (OR, 1.99; 95% CI, 1.12-3.52; p = 0.02).

CONCLUSIONS

In this large cohort of modern combat casualties, ARDS risk factors included female sex, higher injury severity, hypotension, and tachycardia, but not explosion injury. Patients with ARDS also required more medical resources and were at greater risk of death compared with patients without ARDS. Thus, ARDS remains a significant complication in current combat casualty care.

LEVEL OF EVIDENCE

Prognostic/epidemiologic study, level III.

Acute Respiratory Distress Syndrome Incidence, but Not Mortality, Has Decreased Nationwide: A National Trauma Data Bank Study

Acute respiratory distress syndrome (ARDS) incidence is reported to have decreased in recent years. However, no large-scale study to date has exclusively examined ARDS in the critically injured. We sought to examine the national incidence of ARDS and its associated outcomes exclusively in adult trauma patients. The National Trauma Data Bank (NTDB) was queried to evaluate the incidence of ARDS and associated outcomes over a 6-year study period (2007–2012). Included patients were ≥18 years old, with at least one ventilator day, and complications recorded. ARDS-associated outcomes and complications were also analyzed. Mean age increased over the study period (48.1–51.4 years, P < 0.003). ARDS incidence decreased from 21.5 to 8.5 per cent (P < 0.001). Length of stay (LOS), intensive care unit LOS (ICU LOS), and ventilator days decreased over time. Mortality increased from 21.3 to 24.9 per cent (P < 0.002). Incidence of pneumonia and acute kidney injury increased marginally (39.5–40.9% and 11.4–12.3%, respectively). Sepsis trended down from 2007 to 2010, after which comparable NTDB data were not available. ARDS incidence in mechanically ventilated adult trauma patients has decreased significantly in recent years. We theorize this is likely attributable to improved critical care strategies. Unlike ARDS incidence, mortality in this patient population has not improved despite these advancements.

Pneumonitis and pneumonia after aspiration

Aspiration pneumonitis and aspiration pneumonia are clinical syndromes caused by aspiration. These conditions are clinically significant due to their high morbidity and mortality. However, aspiration as a preceding event are often unwitnessed, particularly in cases of asymptomatic or silent aspiration. Furthermore, despite the difference in treatment approaches for managing aspiration pneumonitis and aspiration pneumonia, these two disease entities are often difficult to discriminate from one another, resulting in inappropriate treatment. The use of unclear terminologies hinders the comparability among different studies, making it difficult to produce evidence-based conclusions and practical guidelines. We reviewed the most recent studies to define aspiration, aspiration pneumonitis, and aspiration pneumonia, and to further assess these conditions in terms of incidence and epidemiology, pathophysiology, risk factors, diagnosis, management and treatment, and prevention.

Association between ventilatory settings and development of acute respiratory distress syndrome in mechanically ventilated patients due to brain injury

PURPOSE

In neurologically critically ill patients with mechanical ventilation (MV), the development of acute respiratory distress syndrome (ARDS) is a major contributor to morbidity and mortality, but the role of ventilatory management has been scarcely evaluated. We evaluate the association of tidal volume, level of PEEP and driving pressure with the development of ARDS in a population of patients with brain injury.

MATERIALS AND METHODS

We performed a secondary analysis of a prospective, observational study on mechanical ventilation.

RESULTS

We included 986 patients mechanically ventilated due to an acute brain injury (hemorrhagic stroke, ischemic stroke or brain trauma). Incidence of ARDS in this cohort was 3%. Multivariate analysis suggested that driving pressure could be associated with the development of ARDS (odds ratio for unit increment of driving pressure 1.12; confidence interval for 95%: 1.01 to 1.23) whereas we did not observe association for tidal volume (in ml per kg of predicted body weight) or level of PEEP. ARDS was associated with an increase in mortality, longer duration of mechanical ventilation, and longer ICU length of stay.

CONCLUSIONS

In a cohort of brain-injured patients the development of ARDS was not common. Driving pressure was associated with the development of this disease.

Lung complications are common in intensive care treated patients with pelvis fractures: a retrospective cohort study

Background

The incidence of severe respiratory complications in patients with pelvis fractures needing intensive care have not previously been studied. Therefore, the aims of this registry study were to 1) determine the number of ICU patients with pelvis fractures who had severe respiratory complications 2) whether the surgical intervention in these patients is associated with the pulmonary condition and 3) whether there is an association between lung complications and mortality. We hypothesized that acute hypoxic failure (AHF) and acute respiratory distress syndrome (ARDS) 1) are common in ICU treated patients with pelvis fractures, 2) are not related to the reconstructive surgery, or to 3) to mortality.

Methods

All patients in the database cohort (n = 112), scheduled for surgical stabilization of pelvis ring and/or acetabulum fractures, admitted to the general ICU at Uppsala University Hospital between 2007 and 2014 for intensive care were included.

Results

The incidence of AHF/ARDS was 67 % (75/112 patients), i.e., the percentage of patients that at any period during the ICU stay fulfilled the AHF/ARDS criteria. The incidence of AHF was 44 % and incidence of ARDS was 23 %. The patients with AHF/ARDS had more lung contusions and pneumonia than the patients without AHF/ARDS. Overall, there were no significant changes in oxygenation variables associated with surgery. However, 23 patients with pre-operative normal lung status developed AHF/ARDS in relation to the surgical procedure, whereas 12 patients with AHF/ARDS normalized their lung condition. The patients who developed AHF/ARDS had a higher incidence of lung contusion (P = 0.04) and the surgical stabilization was performed earlier (5 versus 10 days) in these patients (P = 0.03).

Conclusions

We found that the incidence of respiratory failure in ICU treated patients with pelvis fractures was high, that the procedure around surgical stabilization seems to be associated with a worsening in the respiratory function in patients with lung contusion, and that mortality was low and was probably not related to the respiratory condition.

Trial registration

Study was registered at ISRCTN.org number, ISRCTN10335587.

Reducing acute respiratory distress syndrome occurrence using mechanical ventilation

The standard treatment for acute respiratory distress syndrome (ARDS) is supportive in the form of low tidal volume ventilation applied after significant lung injury has already developed. Nevertheless, ARDS mortality remains unacceptably high (> 40%). Indeed, once ARDS is established it becomes refractory to treatment, and therefore avoidance is key. However, preventive techniques and therapeutics to reduce the incidence of ARDS in patients at high-risk have not been validated clinically. This review discusses the current data suggesting that preemptive application of the properly adjusted mechanical breath can block progressive acute lung injury and significantly reduce the occurrence of ARDS.

Misclassification of acute respiratory distress syndrome after traumatic injury: The cost of less rigorous approaches

BACKGROUND

Adherence to rigorous research protocols for identifying adult respiratory distress syndrome (ARDS) after trauma is variable. To examine how misclassification of ARDS may bias observational studies in trauma populations, we evaluated the agreement of two methods for adjudicating ARDS after trauma: the current gold standard, direct review of chest radiographs and review of dictated radiology reports, a commonly used alternative.

METHODS

This nested cohort study included 123 mechanically ventilated patients between 2005 and 2008, with at least one PaO2/FIO2 less than 300 within the first 8 days of admission. Two blinded physician investigators adjudicated ARDS by two methods. The investigators directly reviewed all chest radiographs to evaluate for bilateral infiltrates. Several months later, blinded to their previous assessments, they adjudicated ARDS using a standardized rubric to classify radiology reports. A κ statistics was calculated. Regression analyses quantified the association between established risk factors as well as important clinical outcomes and ARDS determined by the aforementioned methods as well as hypoxemia as a surrogate marker.

RESULTS

The κ was 0.47 for the observed agreement between ARDS adjudicated by direct review of chest radiographs and ARDS adjudicated by review of radiology reports. Both the magnitude and direction of bias on the estimates of association between ARDS and established risk factors as well as clinical outcomes varied by method of adjudication.

CONCLUSION

Classification of ARDS by review of dictated radiology reports had only moderate agreement with the current gold standard, ARDS adjudicated by direct review of chest radiographs. While the misclassification of ARDS had varied effects on the estimates of associations with established risk factors, it tended to weaken the association of ARDS with important clinical outcomes. A standardized approach to ARDS adjudication after trauma by direct review of chest radiographs will minimize misclassification bias in future observational studies.

LEVEL OF EVIDENCE

Diagnostic study, level II.

The association between the Th-17 immune response and pulmonary complications in a trauma ICU population

BACKGROUND

The overall immunopathology of the T-helper cell (Th)-17 immune response has been implicated in various inflammatory diseases including pulmonary inflammation; however its potential role in acute respiratory distress syndrome (ARDS) is not defined. This study aimed to evaluate the Th-17 response in bronchoalveolar lavage fluid (BALF) and blood and from trauma patients with pulmonary complications.

METHODS

A total of 21 severely injured intensive care unit (ICU) subjects, who were mechanically ventilated and undergoing bronchoscopy, were enrolled. BALF and blood were collected and analyzed for Th-1 (interferon [IFN]γ), Th-2 (interleukin [IL]-4, -10), Th-17 (IL-17A, -17F, -22, 23) and pro-inflammatory (IL-1β, IL-6, tumor necrosis factor [TNF]α) cytokine levels.

RESULTS

Significant levels of the Th-17 cytokines IL-17A, -17F and -21 and IL-6 (which can be classified as a Th-17 cytokine) were observed in the BALF of all subjects. There were no significant differences in Th-17 cytokines between those subjects with ARDS and those without, with the exception of plasma and BALF IL-6, which was markedly greater in ARDS subjects, as compared with controls and non-ARDS subjects.

CONCLUSIONS

Trauma patients with pulmonary complications exhibited a significant Th-17 response in the lung and blood, suggesting that this pro-inflammatory milieu may be a contributing factor to such complications.

Who cares about preventing acute respiratory distress syndrome?

Acute respiratory distress syndrome (ARDS) is a common, lethal, and morbid respiratory complication primarily seen in the setting of major trauma and infection. Despite advances in mechanical ventilation for ARDS, many interventions have not been successful in reducing mortality. Recent grant announcements and ongoing clinical trials indicate an interest in preventing ARDS. This Perspective challenges some of the basic assumptions of ARDS prevention and preventive care in the intensive care unit. ARDS is an organ function surrogate outcome. Studies of surrogate outcomes in medicine have repeatedly failed to show an association with patient-centered outcomes that might include mortality, quality of life, patient satisfaction, and cost. Organ failure surrogate outcomes in critical care, including oxygenation, cardiac output, and blood pressure, have similarly failed to show a consistent association with patient-centered benefit. Trials designed to demonstrate an effect on surrogate outcomes will rarely be able to demonstrate small, but important, harms so that the net benefit of prevention can be calculated. This will leave clinicians with insufficient information to balance the unknown benefits of ARDS prevention with imprecisely estimated costs or risks of prevention. Because ARDS diagnosis relies on oxygenation and the chest radiograph that might be directly influenced by the prophylactic intervention, studies must be designed to insure that the prevention is not merely cosmetic. Strategies that prevent ARDS need to be tested in trials sufficiently powered to demonstrate their patient-centered costs, benefits and harms before widespread adoption.

APACHE III Outcome Prediction in Patients Admitted to the Intensive Care Unit with Sepsis Associated Acute Lung Injury

BACKGROUND AND OBJECTIVE

Acute Physiology and Chronic Health Evaluation (APACHE) III score has been widely used for prediction of clinical outcomes in mixed critically ill patients. However, it has not been validated in patients with sepsis-associated acute lung injury (ALI). The aim of the study was to explore the calibration and predictive value of APACHE III in patients with sepsis-associated ALI.

METHOD

The study was a secondary analysis of a prospective randomized controlled trial investigating the efficacy of rosuvastatin in sepsis-associated ALI (Statins for Acutely Injured Lungs from Sepsis, SAILS). The study population was sepsis-related ALI patients. The primary outcome of the current study was the same as in the original trial, 60-day in-hospital mortality, defined as death before hospital discharge, censored 60 days after enrollment. Discrimination of APACHE III was assessed by calculating the area under the receiver operating characteristic (ROC) curve (AUC) with its 95% CI. Hosmer-Lemeshow goodness-of-fit statistic was used to assess the calibration of APACHE III. The Brier score was reported to represent the overall performance of APACHE III in predicting outcome.

MAIN RESULTS

A total of 745 patients were included in the study, including 540 survivors and 205 non-survivors. Non-survivors were significantly older than survivors (59.71 ± 16.17 vs 52.00 ± 15.92 years, p < 0.001). The primary causes of ALI were also different between survivors and non-survivors (p = 0.017). Survivors were more likely to have the cause of sepsis than non-survivors (21.2% vs. 15.1%). APACHE III score was higher in non-survivors than in survivors (106.72 ± 27.30 vs. 88.42 ± 26.86; p < 0.001). Discrimination of APACHE III to predict mortality in ALI patients was moderate with an AUC of 0.68 (95% confidence interval: 0.64-0.73).

CONCLUSION

this study for the first time validated the discrimination of APACHE III in sepsis associated ALI patients. The result shows that APACHE III score has moderate predictive value for in-hospital mortality among adults with sepsis-associated acute lung injury.

Myeloid knockout of HIF-1 α does not markedly affect hemorrhage/resuscitation-induced inflammation and hepatic injury

BACKGROUND

Hypoxia-inducible factor-1 α (HIF-1 α ) and NF- κ B play important roles in the inflammatory response after hemorrhagic shock and resuscitation (H/R). Here, the role of myeloid HIF-1 α in liver hypoxia, injury, and inflammation after H/R with special regard to NF- κ B activation was studied.

METHODS

Mice with a conditional HIF-1 α knockout (KO) in myeloid cell-line and wild-type (WT) controls were hemorrhaged for 90 min (30 ± 2 mm Hg) and resuscitated. Controls underwent only surgical procedures.

RESULTS

After six hours, H/R enhanced the expression of HIF-1 α -induced genes vascular endothelial growth factor (VEGF) and adrenomedullin (ADM). In KO mice, this was not observed. H/R-induced liver injury in HIF-1 α KO was comparable to WT. Elevated plasma interleukin-6 (IL-6) levels after H/R were not reduced by HIF-1 α KO. Local hepatic hypoxia was not significantly reduced in HIF-1 α KO compared to controls after H/R. H/R-induced NF- κB phosphorylation in liver did not significantly differ between WT and KO.

CONCLUSIONS

Here, deleting HIF-1 α in myeloid cells and thereby in Kupffer cells was not protective after H/R. This data indicates that other factors, such as NF- κB, due to its upregulated phosphorylation in WT and KO mice, contrary to HIF-1 α, are rather key modulators of inflammation after H/R in our model.