The decreasing incidence of late posttraumatic acute respiratory distress syndrome: the potential role of lung protective ventilation and conservative transfusion practice

Early Fluid is Less Fluid: Comparing Early Versus Late Resuscitation in Severely Injured Trauma Patients

Background

We aimed to characterize the temporal trends of crystalloid resuscitation in severely injured trauma patients after intensive care unit (ICU) admission. Using 500 mL/hr of crystalloid in the first 6 hours of ICU admission to distinguish early versus late resuscitation, we hypothesized early resuscitation was associated with less volume by 48 hours and better outcomes compared with late resuscitation.

Methods

We performed a retrospective review of the trauma registry of a high-volume level 1 academic trauma center to examine adult trauma patients admitted to the ICU (2016-2019) with: with initial serum lactate ≥ 4 mmol/dL, elevated lactate (≥ 2 mmol/L) at ICU admission, and lactate normalization within 48 hours. We analyzed patient and injury characteristics, and the first 48 hours of ICU course. The primary outcome was ICU length of stay (LOS); secondary outcomes included ventilator days, acute kidney injury (AKI), and in-hospital death. We compared subjects who received early resuscitation to those received late resuscitation using unadjusted methods and multivariable regression models.

Results

We analyzed 333 subjects. The late resuscitation group received less volume over the first 24 hours, but surpassed the early group by 48 hours (5.5 vs 4.1L, p ≤ 0.001). The late group had longer ICU LOS (9 vs 5 days, p ≤ 0.001) and ventilator days (5 vs 2 days, p ≤ 0.001), and higher incidence of AKI (38% vs 11%, p ≤ 0.001). On multivariable regression, late resuscitation remained associated with longer ICU LOS and ventilator days, and higher odds of AKI after adjusting for important confounders.

Conclusions

After hemostasis, crystalloid can play an important role in restoration of organ perfusion. Delaying resuscitation is associated with both receipt of higher volumes of crystalloid by 48 hours and worse outcomes compared to early resuscitation. Judicious crystalloid given early in ICU admission could improve outcomes in the severely injured.

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.

Temporal Changes in Ventilator Settings in Patients With Uninjured Lungs: A Systematic Review

In patients with uninjured lungs, increasing evidence indicates that tidal volume (VT) reduction improves outcomes in the intensive care unit (ICU) and in the operating room (OR). However, the degree to which this evidence has translated to clinical changes in ventilator settings for patients with uninjured lungs is unknown. To clarify whether ventilator settings have changed, we searched MEDLINE, Cochrane Central Register of Controlled Trials, and Web of Science for publications on invasive ventilation in ICUs or ORs, excluding those on patients <18 years of age or those with >25% of patients with acute respiratory distress syndrome (ARDS). Our primary end point was temporal change in VT over time. Secondary end points were changes in maximum airway pressure, mean airway pressure, positive end-expiratory pressure, inspiratory oxygen fraction, development of ARDS (ICU studies only), and postoperative pulmonary complications (OR studies only) determined using correlation analysis and linear regression. We identified 96 ICU and 96 OR studies comprising 130,316 patients from 1975 to 2014 and observed that in the ICU, VT size decreased annually by 0.16 mL/kg (-0.19 to -0.12 mL/kg) (P < .001), while positive end-expiratory pressure increased by an average of 0.1 mbar/y (0.02-0.17 mbar/y) (P = .017). In the OR, VT size decreased by 0.09 mL/kg per year (-0.14 to -0.04 mL/kg per year) (P < .001). The change in VTs leveled off in 1995. Other intraoperative ventilator settings did not change in the study period. Incidences of ARDS (ICU studies) and postoperative pulmonary complications (OR studies) also did not change over time. We found that, during a 39-year period, from 1975 to 2014, VTs in clinical studies on mechanical ventilation have decreased significantly in the ICU and in the OR.

Survival following traumatic thoracic compartment syndrome managed with VV-ECMO

Whilst post-traumatic respiratory failure is the most common indication for use of VV-ECMO in trauma patients, its use in traumatic thoracic compartment syndrome is not yet well described. Thoracic compartment syndrome, a rare complication of thoracic trauma, occurs in the setting of chest wall injuries, impaired chest wall compliance, pulmonary contusions and subsequent high ventilatory pressures. This in turn impairs venous return and increases risk of circulatory arrest due to obstructive shock. This case study describes the successful use of VV-ECMO in a young male with thoracic compartment syndrome following severe blunt chest trauma sustained in a high speed motor vehicle crash. Following brief circulatory arrest, thoracic compartment syndrome was relieved during thoracotomy but reoccurred on chest closure. The use of VV-ECMO for oxygenation permitted lower ventilatory pressures, allowing venous return and primary closure of the thoracotomy. The patient subsequently had an excellent functional outcome. This case describes the successful use of VV-ECMO for a novel indication. The indications for ECMO in thoracic trauma patients continue to evolve.

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.

Risk Factors on Hospital Arrival for Acute Respiratory Distress Syndrome Following Pediatric Trauma

OBJECTIVES

To determine risk factors identifiable at hospital arrival associated with acute respiratory distress syndrome development among critically injured children.

DESIGN

Retrospective cohort study.

SETTING

Level I or II adult or pediatric trauma centers contributing to the National Trauma Data Bank from 2007 to 2016.

PATIENTS

Patients less than 18 years admitted to an ICU with traumatic injury.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We determined associations between patient, injury, and clinical characteristics present at hospital arrival with development of acute respiratory distress syndrome recorded as a hospital complication. Acute respiratory distress syndrome occurred in 1.8% of 146,058 critically injured children (n = 2,590). The only demographic factor associated with higher risk of developing acute respiratory distress syndrome on multivariable analysis was African American race (relative risk, 1.42 vs white; 95% CI, 1.13-1.78). Injury characteristics included firearm injuries (relative risk 1.93; 1.50-2.48) and motor vehicle crashes (relative risk, 1.91; 1.57-2.31) relative to falls; spine (relative risk, 1.39; 1.20-1.60), chest (relative risk, 1.36; 1.22-1.52), or lower extremity injuries (relative risk, 1.26; 1.10-1.44); amputations (relative risk, 2.10; 1.51-2.91); and more severe injury (relative risk, 3.69 for Injury Severity Score 40-75 vs 1-8; 2.50-5.44). Clinical variables included abnormal respiratory status (intubated relative risk, 1.67; 1.23-2.26 and hypopnea relative risk, 1.23; 1.05-1.45 and tachypnea relative risk, 1.26; 1.10-1.44) and lower Glasgow Coma Scale score (relative risk, 5.61 for Glasgow Coma Scale score 3 vs 15; 4.44-7.07).

CONCLUSIONS

We provide the first description of the incidence of and risk factors for acute respiratory distress syndrome among pediatric trauma patients. Improved understanding of the risk factors associated with acute respiratory distress syndrome following pediatric trauma may help providers anticipate its development and intervene early to improve outcomes for severely injured children.

Predictors of postinjury acute respiratory distress syndrome: Lung injury persists in the era of hemostatic resuscitation

BACKGROUND

Acute respiratory distress syndrome (ARDS) following trauma is historically associated with crystalloid and blood product exposure. Advances in resuscitation have occurred over the last decade, but their impact on ARDS is unknown. We sought to investigate predictors of postinjury ARDS in the era of hemostatic resuscitation.

METHODS

Data were prospectively collected from arrival to 28 days for 914 highest-level trauma activations who required intubation and survived more than 6 hours from 2005 to 2016 at a Level I trauma center. Patients with ratio of partial pressure of oxygen to fraction of inspired oxygen of 300 mmHg or less during the first 8 days were identified. Two blinded expert clinicians adjudicated all chest radiographs for bilateral infiltrates in the first 8 days. Those with left-sided heart failure detected were excluded. Multivariate logistic regression was used to define predictors of ARDS.

RESULTS

Of the 914 intubated patients, 63% had a ratio of partial pressure of oxygen to fraction of inspired oxygen of 300 or less, and 22% developed ARDS; among the ARDS cases, 57% were diagnosed early (in the first 24 hours), and 43% later. Patients with ARDS diagnosed later were more severely injured (ISS 32 vs. 20, p = 0.001), with higher rates of blunt injury (84% vs. 72%, p = 0.008), chest injury (58% vs. 36%, p < 0.001), and traumatic brain injury (72% vs. 48%, p < 0.001) compared with the no ARDS group. In multivariate analysis, head/chest Abbreviated Injury Score scores, crystalloid from 0 to 6 hours, and platelet transfusion from 0 to 6 hours and 7 to 24 hours were independent predictors of ARDS developing after 24 hours.

CONCLUSIONS

Blood and plasma transfusion were not independently associated with ARDS. However, platelet transfusion was a significant independent risk factor. The role of platelets warrants further investigation but may be mechanistically explained by lung injury models of pulmonary platelet sequestration with peripheral thrombocytopenia.

LEVEL OF EVIDENCE

Prognostic study, level IV.

Pediatric trauma-associated acute respiratory distress syndrome: Incidence, risk factors, and outcomes

BACKGROUND/PURPOSE

Acute Respiratory Distress Syndrome (ARDS) results in significant morbidity and mortality in pediatric trauma victims. The objective of this study was to determine risk factors and outcomes specifically related to pediatric trauma-associated ARDS (PT-ARDS).

METHODS

A retrospective cohort (2007-2014) of children ≤18 years old from the American College of Surgeons National Trauma Data Bank (NTDB) was used to analyze incidence, risk factors, and outcomes related to PT-ARDS.

RESULTS

PT-ARDS was identified in 0.5% (2660/488,381) of the analysis cohort, with an associated mortality of 18.6% (494/2660). Mortality in patients with PT-ARDS most commonly occurred in the first week after injury. Risk factors associated with the development of PTARDS included nonaccidental trauma, near drowning, severe injury (AIS ≥ 3) to the head or chest, pneumonia, sepsis, thoracotomy, laparotomy, transfusion, and total parenteral nutrition use. After adjustment for age, injury complexity, injury mechanism, and physiologic variables, PT-ARDS was found to be independently associated with higher mortality (adjusted OR 1.33, 95% CI 1.18-1.51, p < 0.001).

CONCLUSIONS

PT-ARDS is a rare complication in pediatric trauma patients, but is associated with substantial mortality within 7 days of injury. Recognition and initiation of lung-protective measures early in the postinjury course may represent the best opportunity to change outcomes.

LEVEL OF EVIDENCE

Level 3 - Epidemiologic.

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.

Risk Factors for the Development of Acute Respiratory Distress Syndrome Following Hemorrhage

BACKGROUND

The Pragmatic Randomized Optimal Platelet and Plasma Ratios (PROPPR) study evaluated the effects of plasma and platelets on hemostasis and mortality after hemorrhage. The pulmonary consequences of resuscitation strategies that mimic whole blood, remain unknown.

METHODS

A secondary analysis of the PROPPR study was performed. Injured patients predicted to receive a massive transfusion were randomized to 1:1:1 versus 1:1:2 plasma-platelet-red blood cell ratios at 12 Level I North American trauma centers. Patients with survival >24 h, an intensive care unit (ICU) stay, and a recorded PaO2/FiO2 (P/F) ratio were included. Acute respiratory distress syndrome (ARDS) was defined as a P/F ratio < 200, with bilateral pulmonary infiltrates, and adjudicated by investigators.

RESULTS

Four hundred fifty-four patients were reviewed (230 received 1:1:1, 224 1:1:2). Age, sex, injury mechanism, and regional abbreviated injury scale (AIS) scores did not differ between cohorts. Tidal volume, positive end-expiratory pressure, and lowest P/F ratio did not differ. No significant differences in ARDS rates (14.8% vs. 18.4%), ventilator-free (24 vs. 24) or ICU-free days (17.5 vs. 18), hospital length of stay (22 days vs. 18 days), or 30-day mortality were found (28% vs. 28%). ARDS was associated with blunt injury (OR 3.61 [1.53-8.81] P < 0.01) and increasing chest AIS (OR 1.40 [1.15-1.71] P < 0.01). Each 500 mL of crystalloid infused during hours 0 to 6 was associated with a 9% increase in the rate of ARDS (OR 1.09 [1.04-1.14] P < 0.01). Blood given at 0 to 6 or 7 to 24 h were not risk factors for lung injury.

CONCLUSION

Acute crystalloid exposure, but not blood products, is a potentially modifiable risk factor for the prevention of ARDS following hemorrhage.

Optimal ventilator strategies for trauma-related ARDS

BACKGROUND

Acute respiratory distress syndrome (ARDS) was first described in the 1960s and has become a major area of research due to the mortality and morbidity associated with it. ARDS is currently defined using the Berlin Consensus; however, this is not wholly applicable for trauma-related ARDS.

METHODS

A systematic review of the literature was undertaken using the Preferred Reporting for Systematic Reviews and Meta Analyses methodology. The Ovid Medline, Web of Science and PubMed online databases were interrogated for papers published between 1 January 1995 and 31 December 2017.

RESULTS

The literature search yielded a total of 64 papers that fulfilled the search criteria.

CONCLUSIONS

Despite decades of dedicated research into different treatment modalities, ARDS continues to carry a high burden of mortality. The ARDS definitions laid out in the Berlin consensus are not entirely suited to trauma. While trauma-related ARDS represents a small portion of the available research, the evidence continues to favour low tidal volume ventilation as the benchmark for current practice. Positive end expiratory ventilation and airway pressure release ventilation in trauma cohorts may be beneficial; however, the evidence to date does not show this.

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.

Nonoperative Management of the Damaged Spleen: A Community Surgeon Looks Back

Blunt spleen injury is usually managed nonoperatively. An 8-year retrospective analysis by one community surgeon was done to provide an overview of the role of CT, angiography, and transfusion in the management algorithm. A total of 2750 patients were screened and 125 patients were identified with spleen injury. Of these 125 patients, 72 were managed without surgery. These were young (mean age 32 ± 16 years) patients with mean Injury Severity Score of 16 ± 8. Angiography was used in 14 patients. These patients received more blood (5 ± 6 vs 2 ± units of packed red blood cells) than their nonangiogram counterparts. Overall failure of nonoperative care was 3 per cent. Community surgeons can provide safe nonoperative care and current adjuncts including angi-ography may enhance splenic salvage.

Clinical Practice Guideline of Acute Respiratory Distress Syndrome

There is no well-stated practical guideline for mechanically ventilated patients with or without acute respiratory distress syndrome (ARDS). We generate strong (1) and weak (2) grade of recommendations based on high (A), moderate (B) and low (C) grade in the quality of evidence. In patients with ARDS, we recommend low tidal volume ventilation (1A) and prone position if it is not contraindicated (1B) to reduce their mortality. However, we did not support high-frequency oscillatory ventilation (1B) and inhaled nitric oxide (1A) as a standard treatment. We also suggest high positive end-expiratory pressure (2B), extracorporeal membrane oxygenation as a rescue therapy (2C), and neuromuscular blockage for 48 hours after starting mechanical ventilation (2B). The application of recruitment maneuver may reduce mortality (2B), however, the use of systemic steroids cannot reduce mortality (2B). In mechanically ventilated patients, we recommend light sedation (1B) and low tidal volume even without ARDS (1B) and suggest lung protective ventilation strategy during the operation to lower the incidence of lung complications including ARDS (2B). Early tracheostomy in mechanically ventilated patients can be performed only in limited patients (2A). In conclusion, of 12 recommendations, nine were in the management of ARDS, and three for mechanically ventilated patients.

The acute respiratory distress syndrome following isolated severe traumatic brain injury

BACKGROUND

Acute respiratory distress syndrome (ARDS) is common after traumatic brain injury (TBI) and is associated with worse neurologic outcomes and longer hospitalization. However, the incidence and associated causes of ARDS in isolated TBI have not been well studied.

METHODS

We performed a subgroup analysis of 210 consecutive patients with isolated severe TBI enrolled in a prospective observational cohort at a Level 1 trauma center between 2005 and 2014. Subjects required endotracheal intubation and had isolated severe TBI defined by a head Abbreviated Injury Scale (AIS) score of 3 or greater and AIS score lower than 3 in all other categories. ARDS within the first 8 days of admission was rigorously adjudicated using Berlin criteria. Regression analyses were used to test the association between predictors of interest and ARDS.

RESULTS

The incidence of ARDS in the first 8 days after severe isolated TBI was 30%. Patients who developed ARDS were administered more crystalloids (4.3 L vs. 3.5 L, p = 0.005) and blood products in the first 12 hours of admission. Patients with ARDS had significantly worse clinical outcomes measured at 28 days, including longer median intensive care unit and hospital stays (4 days vs. 13 days, p < 0.001, and 7.5 days vs. 14.5 days, p < 0.001, respectively). In unadjusted logistic regression analyses, the odds of developing ARDS were significantly associated with head AIS score (odds ratio [OR], 1.8; p = 0.018), male sex (OR, 2.9; p = 0.012), and early transfusion of platelets (OR, 2.8; p = 0.003). These associations were similar in a multivariate logistic regression model.

CONCLUSION

In the era of balanced hemostatic resuscitation practices, severity of head injury, male sex, early crystalloids, and early transfusion of platelets are associated with a higher risk of ARDS after severe isolated TBI. Early transfusion of platelets after severe TBI may be a modifiable risk factor for ARDS, and these findings invite further investigation into causal mechanisms driving this observed association.

LEVEL OF EVIDENCE

Prognostic/epidemiologic study, level III.

Thoracic Trauma Severity score on admission allows to determine the risk of delayed ARDS in trauma patients with pulmonary contusion

BACKGROUND

Pulmonary contusion is a major risk factor of acute respiratory distress syndrome (ARDS) in trauma patients. As this complication may appear after a free interval of 24-48 h, detection of patients at risk is essential. The main objective of this study was to assess the performance of the Thoracic Trauma Severity (TTS) score upon admission in predicting delayed ARDS in blunt trauma patients with pulmonary contusion.

METHODS

All blunt thoracic trauma patients admitted consecutively to our trauma centre between January 2005 and December 2009 were retrospectively included if they presented a pulmonary contusion on the admission chest computed tomography scan. Main outcome measure was the presence of moderate or severe ARDS (PaO2/FiO2 ratio≤200) for 48 h or more. The global ability of the TTS score to predict ARDS was studied by ROC curves with a threshold analysis using a grey zone approach.

RESULTS

Of 329 patients studied (75% men, mean age 36.9 years [SD 17.8 years], mean Injury Severity Score 21.7 [SD 16.0]), 82 (25%) presented with ARDS (mean lowest PaO2/FiO2 ratio of 131 [SD 34]). The area under the ROC curves for the TTS score in predicting ARDS was 0.82 (95% CI 0.78-0.86) in the overall population. TTS scores between 8 and 12 belonged to the inconclusive grey zone. A TTS score of 13-25 was found to be independent risk factors of ARDS (OR 25.8 [95% CI 6.7-99.6] P<0.001).

CONCLUSIONS

An extreme TTS score on admission accurately predicts the occurrence of delayed ARDS in blunt thoracic trauma patients affected by pulmonary contusion. This simple score could guide early decision making and management for a non-negligible proportion of this specific population.

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.

Differences in degree, differences in kind: characterizing lung injury in trauma

BACKGROUND

Acute lung injury following trauma remains a significant source of morbidity and mortality. Although multiple trauma studies have used hypoxemia without radiographic adjudication as a surrogate for identifying adult respiratory distress syndrome (ARDS) cases, the differences between patients with hypoxemia alone and those with radiographically confirmed ARDS are not well described in the literature. We hypothesized that nonhypoxemic, hypoxemic, and ARDS patients represent distinct groups with unique characteristics and predictors.

METHODS

Laboratory, demographic, clinical, and outcomes data were prospectively collected from 621 intubated, critically injured patients at an urban Level 1 trauma center from 2005 to 2013. Hypoxemia was defined as PaO2/FIO2 ratio of 300 or lower. ARDS was adjudicated using Berlin criteria, with blinded two-physician consensus review of chest radiographs. Group comparisons were performed by hypoxemia and ARDS status. Logistic regression analyses were performed to separately assess predictors of hypoxemia and ARDS.

RESULTS

Of the 621 intubated patients, 64% developed hypoxemia; 46% of these hypoxemic patients developed ARDS by chest radiograph. Across the three groups (no hypoxemia, hypoxemia, ARDS), there were no significant differences in age, sex, or comorbidities. However, there was an increase in severity of shock, injury, and chest injury by group, with corresponding trends in transfusion requirements and volume of early fluid administration. Outcomes followed a similar stepwise pattern, with pneumonia, multiorgan failure, length of intensive care unit stay, number of ventilator days, and overall mortality highest in ARDS patients. In multiple logistic regression, early plasma transfusion, delayed crystalloid administration, body mass index, and head and chest injury were independent predictors of hypoxemia, while head and chest injury, early crystalloid infusion, and delayed platelet transfusion were independent predictors of ARDS.

CONCLUSION

Hypoxemia and ARDS exist on a spectrum of respiratory dysfunction following trauma, with increasing injury severity profiles and resuscitation requirements. However, they also represent distinct clinical states with unique predictors, which require directed research approaches and targeted therapeutic strategies.

LEVEL OF EVIDENCE

Prognostic and epidemiologic study, level III.

Organ-protective effects on the liver and kidney by minocycline in small piglets undergoing cardiopulonary bypass

Cardiopulmonary bypass (CPB) often is required for the operative correction of congenital heart defects in small infants. Unfortunately, CPB is associated with injury of inner organs such as the brain, kidney, lung, and liver. Renal failure and increase in liver enzymes are typical side effects observed after CPB. Here, we investigate whether organ protection of the kidney and liver can be achieved with the application of minocycline, which is known-besides its anti-infective effects-to act as a poly-ADP-ribose-polymerase inhibitor. Twenty-nine 4-week-old Angler Sattelschwein-piglets (8-15 kg) were divided into four groups: control group (n = 8), CPB group (n = 9), minocycline-control group (n = 6), and the minocycline-CPB group (n = 6). CPB groups were thoracotomized and underwent CPB for 120 min (cross-clamp, 90 min; reperfusion, 30 min) followed by a 90-min recovery time. The control groups also were thoracotomized but not connected to CPB. The minocycline group received 4 mg/kg minocycline before and 2 mg/kg after CPB. In the kidneys, CPB histologically resulted in widening of Bowman's capsule, and-mainly in tubules-formation of poly-ADP-ribose, nitrosylation of tyrosine-residues, nuclear translocation of hypoxia-induced factor HIF-1α, and of apoptosis-inducing factor (AIF). In addition, we found significantly less ATP in the kidney and significantly increased plasma urea and creatinine. Similar but gradually attenuated changes were found in the liver together with significantly elevated de-Ritis coefficient. These changes in the kidney and liver were significantly diminished by minocycline (except AIF in the liver which was similar in all groups). In conclusion, CPB causes damage in the kidney and-to a lower degree-in the liver, which can be attenuated by minocycline.

Heterogeneous phenotypes of acute respiratory distress syndrome after major trauma

RATIONALE

Acute respiratory distress syndrome (ARDS) is a heterogeneous syndrome that can develop at various times after major trauma.

OBJECTIVES

To identify and characterize distinct phenotypes of ARDS after trauma, based on timing of syndrome onset.

METHODS

Latent class analyses were used to identify patterns of ARDS onset in a cohort of critically ill trauma patients. Identified patterns were tested for associations with known ARDS risk factors and associations were externally validated at a separate institution. Eleven plasma biomarkers representing pathophysiologic domains were compared between identified patterns in the validation cohort.

MEASUREMENTS AND MAIN RESULTS

Three patterns of ARDS were identified; class I (52%) early onset on Day 1 or 2, class II (40%) onset on Days 3 and 4, and class III (8%) later onset on Days 4 and 5. Early-onset ARDS was associated with higher Abbreviated Injury Scale scores for the thorax (P < 0.001), lower lowest systolic blood pressure before intensive care unit admission (P = 0.003), and a greater red blood cell transfusion requirement during resuscitation (P = 0.030). In the external validation cohort, early-onset ARDS was also associated with a higher Abbreviated Injury Scale score for the thorax (P = 0.001) and a lower lowest systolic blood pressure before intensive care unit enrollment (P = 0.006). In addition, the early-onset phenotype demonstrated higher plasma levels of soluble receptor for advanced glycation end-products and angiopoietin-2.

CONCLUSIONS

Degree of hemorrhagic shock and severity of thoracic trauma are associated with an early-onset phenotype of ARDS after major trauma. Lung injury biomarkers suggest a dominant alveolar-capillary barrier injury pattern in this phenotype.

Risks associated with red blood cell transfusion in the trauma population, a meta-analysis

INTRODUCTION

A previous meta-analysis has found an association between red blood cell (RBC) transfusions and mortality in critically ill patients, but no review has focused on the trauma population only.

OBJECTIVES

To determine the association between RBC transfusion and mortality in the trauma population, with secondary outcomes of multiorgan failure (MOF) and acute respiratory distress syndrome (ARDS) or acute lung injury (ALI).

DATA SOURCES

EMBASE (1947-2012) and MEDLINE (1946-2012).

STUDY ELIGIBILITY CRITERIA

Randomized controlled trials and observational studies were to be included if they assessed the association between RBC transfusion and either the primary (mortality) or secondary outcomes (MOF, ARDS/ALI).

PARTICIPANTS

Trauma patients.

EXPOSURE

Red blood cell transfusion.

METHODS

A literature search was completed and reviewed in duplicate to identify eligible studies. Studies were included in the pooled analyses if an attempt was made to determine the association between RBC and the outcomes, after adjusting for important confounders. A random effects model was used for and heterogeneity was quantified using the I(2) statistic. Study quality was assessed using the Newcastle-Ottawa Scale.

RESULTS

40 observational studies were included in the qualitative review. Including studies which adjusted for important confounders found the odds of mortality increased with each additional unit of RBC transfused (9 Studies, OR 1.07, 95%CI 1.04-1.10, I(2) 82.9%). The odds of MOF (3 studies, OR 1.08, 95%CI 1.02-1.14, I(2) 95.9%) and ARDS/ALI (2 studies, OR 1.06, 95%CI 1.03-1.10, I(2) 0%) also increased with each additional RBC unit transfused.

CONCLUSIONS

We have found an association between RBC transfusion and the primary and secondary outcomes, based on observational studies only. This represents the extent of the published literature. Further interventional studies are needed to clarify how limiting transfusion can affect mortality and other outcomes.

Impact of distinct definitions of acute lung injury on its incidence and outcomes in Brazilian ICUs: prospective evaluation of 7,133 patients*

OBJECTIVES

Evaluation of prevalence and outcomes of acute lung injury in a large cohort of critically ill patients in Brazil and comparison of predictive receiver operating characteristic curve mortality of American European Consensus conference definition with new Berlin definition of acute respiratory distress syndrome.

DESIGN

A 15-month prospective, multicenter, observational study.

SETTING

Fourteen medical ICUs in Espirito Santo, a state of Brazil.

PATIENTS

Mechanically ventilated patients who fulfilled American European Consensus conference criteria of acute lung injury or Berlin definition of acute respiratory distress syndrome.

INTERVENTIONS

Clinical and respiratory data were collected for 7 consecutive days and on the 14 and 28 days. Twenty-eight day mortality, hospital mortality, and predictive receiver operating characteristic curve mortality were calculated.

MEASUREMENTS AND MAIN RESULTS

Of 7,133 patients, 130 patients (1.8%) fulfilled criteria for acute lung injury (American European Consensus conference) or acute respiratory distress syndrome (Berlin definition). Median time for diagnosis was 2 days (interquartile range, 0-3 d). Main risk factors were pneumonia (35.3%) and nonpulmonary sepsis (31.5%). Mean age was 44.2 ± 15.9 years, and 61.5% were men. Mean Acute Physiology and Chronic Health Evaluation II score was 20.7 ± 7.9. Mean PaO2/FIO2 was 206 ± 61.5, significantly lower in nonsurvivors on day 7 (p = 0.003). Mean mechanical ventilation time was 21 ± 15 days. Length of ICU stay was 26.4 ± 18.7 days. Twenty-eight-day mortality was 38.5% (95% CI, 30.1-46.8); hospital mortality was 49.2% (95% CI, 40.6-57.8). Predictive 28-day mortality area under the receiver operating characteristic curve for American European Consensus conference definition was 0.5625 (95% CI, 0.4783-0.6467) and for the Berlin definition 0.5664 (95% CI, 0.4759-0.6568; p = 0.9510).

CONCLUSIONS

In our population, prevalence of acute lung injury was low, most cases were diagnosed 2 days after ICU admission, and Berlin definition was not different from American European Consensus conference definition in predicting mortality. There are still several problems with the global epidemiology, definition, and mortality predictive indices that should be added to the classification of this still lethal syndrome to improve its predictive mortality power in the future.

Contemporary ventilator management in patients with and at risk of ALI/ARDS

BACKGROUND

Ventilator practices in patients at risk for acute lung injury (ALI) and ARDS are unclear. We examined factors associated with choice of set tidal volumes (VT), and whether VT < 8 mL/kg predicted body weight (PBW) relates to the development of ALI/ARDS.

METHODS

We performed a secondary analysis of a multicenter cohort of adult subjects at risk of lung injury with and without ALI/ARDS at onset of invasive ventilation. Descriptive statistics were used to describe ventilator practices in specific settings and ALI/ARDS risk groups. Logistic regression analysis was used to determine the factors associated with the use of VT < 8 mL/kg PBW and the relationship of VT to ALI/ARDS development and outcome.

RESULTS

Of 829 mechanically ventilated patients, 107 met the criteria for ALI/ARDS at time of intubation, and 161 developed ALI/ARDS after intubation (post-intubation ALI/ARDS). There was significant intercenter variability in initial ventilator settings, and in the incidence of ALI/ARDS and post-intubation ALI/ARDS. The median VT was 7.96 (IQR 7.14-8.94) mL/kg PBW in ALI/ARDS subjects, and 8.45 (IQR 7.50-9.55) mL/kg PBW in subjects without ALI/ARDS (P = .004). VT decreased from 8.40 (IQR 7.38-9.37) mL/kg PBW to 7.97 (IQR 6.90-9.23) mL/kg PBW (P < .001) in those developing post-intubation ALI/ARDS. Among subjects without ALI/ARDS, VT ≥ 8 mL/kg PBW was associated with shorter height and higher body mass index, while subjects with pneumonia were less likely to get ≥ 8 mL/kg PBW. Initial VT ≥ 8 mL/kg PBW was not associated with the post-intubation ALI/ARDS (adjusted odds ratio 1.30, 95% CI 0.74-2.29) or worse outcomes. Post-intubation ALI/ARDS subjects had mortality similar to subjects intubated with ALI/ARDS.

CONCLUSIONS

Clinicians seem to respond to ALI/ARDS with lower initial VT. Initial VT, however, was not associated with the development of post-intubation ALI/ARDS or other outcomes.

Early application of airway pressure release ventilation may reduce mortality in high-risk trauma patients: a systematic review of observational trauma ARDS literature

BACKGROUND

Adult respiratory distress syndrome is often refractory to treatment and develops after entering the health care system. This suggests an opportunity to prevent this syndrome before it develops. The objective of this study was to demonstrate that early application of airway pressure release ventilation in high-risk trauma patients reduces hospital mortality as compared with similarly injured patients on conventional ventilation.

METHODS

Systematic review of observational data in patients who received conventional ventilation in other trauma centers were compared with patients treated with early airway pressure release ventilation in our trauma center. Relevant studies were identified in a PubMed and MEDLINE search from 1995 to 2012 and included prospective and retrospective observational and cohort studies enrolling 100 or more adult trauma patients with reported adult respiratory distress syndrome incidence and mortality data.

RESULTS

Early airway pressure release ventilation as compared with the other trauma centers represented lower mean adult respiratory distress syndrome incidence (14.0% vs. 1.3%) and in-hospital mortality (14.1% vs. 3.9%).

CONCLUSION

These data suggest that early airway pressure release ventilation may prevent progression of acute lung injury in high-risk trauma patients, reducing trauma-related adult respiratory distress syndrome mortality.

LEVEL OF EVIDENCE

Systematic review, level IV.

The changing nature of death on the trauma service

BACKGROUND

Recent innovations in care have improved survival following injury. Coincidentally, the population of elderly injured patients with preexisting comorbidities has increased. We hypothesized that this increase in elderly injured patients may have combined with recent care innovations to alter the causes of death after trauma.

METHODS

We reviewed demographics, injury characteristics, and cause of death of in-hospital deaths of patients admitted to our Level I trauma service from 2000 through 2011. Cause of death was classified as acute hemorrhagic shock; severe traumatic brain injury or high spinal cord injury; complications of preexisting medical condition only (PM); survivable trauma combined with complications of preexisting medical condition (TCoM); multiple-organ failure, sepsis, or adult respiratory distress syndrome (MOF/S/ARDS), or trauma not otherwise categorized (e.g., asphyxiation). Major trauma care advances implemented on our service during the period were identified, and trends in the causes of death were analyzed.

RESULTS

Of the 27,276 admissions, 819 (3%) eligible nonsurvivors were identified for the cause-of-death analyses. Causes of death were severe traumatic brain injury or high spinal cord injury at 44%, acute hemorrhagic shock at 28%, PM at 11%, TCoM at 10%, MOF/S/ARDS at 2%, and trauma not otherwise categorized at 5%. Mean age at death increased across the study interval (range, 47-57 years), while mean Injury Severity Score (ISS) decreased (range, 28-35). There was a significant increase in deaths because of TCoM (3.3-20.9%) and PM (6.7-16.4%), while deaths caused by MOF/S/ARDS decreased from 5% to 0% by 2007. Compared with year 2000, the annual adjusted mortality rate decreased consistently starting in 2009, after the 2002 to 2007 adoption of four major trauma practice guidelines.

CONCLUSION

Mortality caused by preexisting medical conditions has increased, while markedly fewer deaths resulted from the complications of injury. Future improvements in outcomes will require improvement in the management of elderly trauma patients with comorbid conditions.

What the Intensive Care Doctor Needs to Know about Blast-Related Lung Injury

Explosions are currently the primary cause of military combat injuries. A minority of civilian trauma is also caused by explosions. People hurt by explosion are likely to present with complex injuries. The aim of the article is to explain the mechanism underlying these injuries and the associated physiology to help the intensive care clinician manage these casualties properly. The generic term ‘blast injury’ is applied to a collection of injuries caused by explosion. Components of blast injuries have precise definitions relating to the elements of the explosion that caused the injuries: primary blast injury is due to a shock wave, secondary blast injury is caused by fragments and debris colliding with the victim and tertiary blast injury is due to the casualty being thrown against solid objects. Primary blast injury results in damage principally in gas-containing organs, eg the lungs (blast lung) and can lead to impaired pulmonary gas transfer and hypoxaemia. Secondary blast injuries are often penetrating and can lead to haemorrhage while tertiary blast injuries are often blunt and involve substantial tissue damage. Survivors of explosions in confined spaces are more likely to exhibit primary blast injury than those injured in open spaces. The current military approach to immediate management is to apply the C ABC principle (arrest catastrophic haemorrhage first and then deal with airway, breathing and circulation) to achieve Damage Control Resuscitation. Early administration of blood products (plasma as well as red cells) is advocated for those suffering significant haemorrhage. Initial resuscitation is hypotensive to minimise risk of dislodging nascent clots. However, if evacuation is protracted (longer than one hour) then consideration should be given to improving blood flow / oxygen delivery by adopting a revised normotensive blood pressure target to reverse the deleterious consequences of the hypotensive shock state. Animal studies have shown that titrating FiO2 to a target SaO2 of 95% can improve survival and ‘buy time’ during hypotensive resuscitation. Ventilator strategies should use a lung-protective approach with permissive hypercapnia if necessary. Blast casualties are often a challenging group of patients needing expert, tailored, care. Outcome can be good especially in young, otherwise fit, casualties with more than 96% surviving to ICU discharge, although this figure may be lower with a mixed civilian group.

Future clinical applications of genomics for acute respiratory distress syndrome

Acute respiratory distress syndrome remains a substantial cause of morbidity and mortality in intensive care units, yet no specific pharmacotherapy has proven useful in reducing the duration of mechanical ventilation or improving survival. One factor that might hamper the development of treatment for acute respiratory distress syndrome is the heterogeneous nature of the population who present with the syndrome. In this Review, the potential of genomic approaches-genetic association, gene expression, metabolomic, proteomic, and systems biology applications-for the identification of molecular endotypes within acute respiratory distress syndrome and potentially for the prediction, diagnosis, prognosis, and treatment of this difficult disorder are discussed.

Mechanical ventilation and acute lung injury in emergency department patients with severe sepsis and septic shock: an observational study

OBJECTIVES

The objectives were to characterize the use of mechanical ventilation in the emergency department (ED), with respect to ventilator settings, monitoring, and titration and to determine the incidence of progression to acute lung injury (ALI) after admission, examining the influence of factors present in the ED on ALI progression.

METHODS

This was a retrospective, observational cohort study of mechanically ventilated patients with severe sepsis and septic shock (June 2005 to May 2010), presenting to an academic ED with an annual census of >95,000 patients. All patients in the study (n = 251) were analyzed for characterization of mechanical ventilation use in the ED. The primary outcome variable of interest was the incidence of ALI progression after intensive care unit (ICU) admission from the ED and risk factors present in the ED associated with this outcome. Secondary analyses included ALI present in the ED and clinical outcomes comparing all patients progressing to ALI versus no ALI. To assess predictors of progression to ALI, significant variables in univariable analyses at a p ≤ 0.10 level were candidates for inclusion in a bidirectional, stepwise, multivariable logistic regression analysis.

RESULTS

Lung-protective ventilation was used in 68 patients (27.1%) and did not differ based on ALI status. Delivered tidal volume was highly variable, with a median tidal volume delivered of 8.8 mL/kg ideal body weight (IBW; interquartile range [IQR] = 7.8 to 10.0) and a range of 5.2 to 14.6 mL/kg IBW. Sixty-nine patients (27.5%) in the entire cohort progressed to ALI after admission to the hospital, with a mean (±SD) onset of 2.1 (±1) days. Multivariable logistic regression analysis demonstrated that a higher body mass index (BMI), higher Sequential Organ Failure Assessment (SOFA) score, and ED vasopressor use were associated with progression to ALI. There was no association between ED ventilator settings and progression to ALI. Compared to patients who did not progress to ALI, patients progressing to ALI after admission from the ED had an increase in mechanical ventilator duration, vasopressor dependence, and hospital length of stay (LOS).

CONCLUSIONS

Lung-protective ventilation is uncommon in the ED, regardless of ALI status. Given the frequency of ALI in the ED, the progression shortly after ICU admission, and the clinical consequences of this syndrome, the effect of ED-based interventions aimed at reducing the sequelae of ALI should be investigated further.

Lower tidal volume at initiation of mechanical ventilation may reduce progression to acute respiratory distress syndrome: a systematic review

INTRODUCTION

The most appropriate tidal volume in patients without acute respiratory distress syndrome (ARDS) is controversial and has not been rigorously examined. Our objective was to determine whether a mechanical ventilation strategy using lower tidal volume is associated with a decreased incidence of progression to ARDS when compared with a higher tidal volume strategy.

METHODS

A systematic search of MEDLINE, EMBASE, CINAHL, the Cochrane Library, conference proceedings, and clinical trial registration was performed with a comprehensive strategy. Studies providing information on mechanically ventilated patients without ARDS at the time of initiation of mechanical ventilation, and in which tidal volume was independently studied as a predictor variable for outcome, were included. The primary outcome was progression to ARDS.

RESULTS

The search yielded 1,704 studies, of which 13 were included in the final analysis. One randomized controlled trial was found; the remaining 12 studies were observational. The patient cohorts were significantly heterogeneous in composition and baseline risk for developing ARDS; therefore, a meta-analysis of the data was not performed. The majority of the studies (n = 8) showed a decrease in progression to ARDS with a lower tidal volume strategy. ARDS developed early in the course of illness (5 hours to 3.7 days). The development of ARDS was associated with increased mortality, lengths of stay, mechanical ventilation duration, and nonpulmonary organ failure.

CONCLUSIONS

In mechanically ventilated patients without ARDS at the time of endotracheal intubation, the majority of data favors lower tidal volume to reduce progression to ARDS. However, due to significant heterogeneity in the data, no definitive recommendations can be made. Further randomized controlled trials examining the role of lower tidal volumes in patients without ARDS, controlling for ARDS risk, are needed.

Acute respiratory distress syndrome after trauma: development and validation of a predictive model

OBJECTIVE

To determine early clinical predictors of acute respiratory distress syndrome after major traumatic injury and characterize the performance of this acute respiratory distress syndrome prediction model, and two previously published acute respiratory distress syndrome prediction models, in an independent cohort of severely injured patients.

DESIGN

Prospective cohort study.

SETTING

University-affiliated level I trauma center in Seattle, WA, and nine hospitals participating in the Inflammation and Host Response to Injury Consortium.

PATIENTS

Model derivation utilized data from 224 patients participating in a randomized controlled trial. All models were validated in an independent cohort of 1,762 trauma patients.

MEASUREMENTS AND MAIN RESULTS

Variables strongly associated with acute respiratory distress syndrome in bivariate analysis (p<.01) were entered into a multiple logistic regression equation to generate an acute respiratory distress syndrome predictive model. We evaluated the performance of all models using the area under the receiver operator characteristic curve. Acute respiratory distress syndrome occurred in 79 subjects (35%) belonging to the development cohort and in 423 subjects (24%) from the validation cohort. Multivariable predictors of acute respiratory distress syndrome after trauma included subject age, Acute Physiology and Chronic Health Evaluation II Score, injury severity score, and the presence of blunt traumatic injury, pulmonary contusion, massive transfusion, and flail chest injury (area under the receiver operator characteristic curve 0.79 [95% confidence interval 0.73, 0.85]). Validation of the prediction model resulted in an area under the receiver operator characteristic curve of 0.71 (95% confidence interval 0.68, 0.74). Our model's performance in the validation cohort was superior to that of two other published acute respiratory distress syndrome prediction models (0.65 [95% confidence interval 0.63, 0.68] and 0.66 [95% confidence interval 0.64, 0.69], p<.01 for all comparisons).

CONCLUSIONS

Using routinely available clinical data, our prediction model identifies patients at high risk for acute respiratory distress syndrome early after severe traumatic injury. This predictive model could facilitate enrollment of subjects into future clinical trials designed to prevent this serious complication.

Initial assessment of chest X-ray in thoracic trauma patients: Awareness of specific injuries

AIM: To compare the reported injuries on initial assessment of the chest X-ray (CXR) in thoracic trauma patients to a second read performed by a dedicated trauma radiologist.

METHODS: By retrospective analysis of a prospective database, 712 patients with an injury to the chest admitted to the University Medical Center Utrecht were studied. All patients with a CXR were included in the study. Every CXR was re-evaluated by a trauma radiologist, who was blinded for the initial results. The findings of the trauma radiologist regarding rib fractures, pneumothoraces, hemothoraces and lung contusions were compared with the initial reports from the trauma team, derived from the original patient files.

RESULTS: A total of 516 patients with both thorax trauma and an initial CXR were included in the study. After re-evaluation of the initial CXR significantly more lung contusions (53.3% vs 34.1%, P < 0.001), hemothoraces (17.8% vs 11.0%, P < 0.001) and pneumothoraces (34.4% vs 26.4%, P < 0.001) were detected. During initial assessment significantly more rib fractures were reported (69.8% vs 62.3%, P < 0.001).

CONCLUSION: During the initial assessment of a CXR from trauma patients in the emergency department, a significant number of treatment-dictating injuries are missed. More awareness for these specific injuries is needed.

Clinical review: Canadian National Advisory Committee on Blood and Blood Products--Massive transfusion consensus conference 2011: report of the panel

In June 2011 the Canadian National Advisory Committee on Blood and Blood Products sponsored an international consensus conference on transfusion and trauma. A panel of 10 experts and two external advisors reviewed the current medical literature and information presented at the conference by invited international speakers and attendees. The Consensus Panel addressed six specific questions on the topic of blood transfusion in trauma. The questions focused on: ratio-based blood resuscitation in trauma patients; the impact of survivorship bias in current research conclusions; the value of nonplasma coagulation products; the role of protocols for delivery of urgent transfusion; the merits of traditional laboratory monitoring compared with measures of clot viscoelasticity; and opportunities for future research. Key findings include a lack of evidence to support the use of 1:1:1 blood component ratios as the standard of care, the importance of early use of tranexamic acid, the expected value of an organized response plan, and the recommendation for an integrated approach that includes antifibrinolytics, rapid release of red blood cells, and a foundation ratio of blood components adjusted by results from either traditional coagulation tests or clot viscoelasticity or both. The present report is intended to provide guidance to practitioners, hospitals, and policy-makers.

Validation of the Thorax Trauma Severity Score for mortality and its value for the development of acute respiratory distress syndrome

BACKGROUND

The aim of the present study was to evaluate and to validate the Thorax Trauma Severity Score (TTSS) for mortality.

METHODS

By database analysis 712 patients with an injury to the chest admitted to the Universal Medical Center Utrecht between 2000 and 2004 were studied. All patients with a score of ≥1 on the AISthorax were included in the study. The patients' file was evaluated for: TTSS, intensive care unit stay, days on ventilation, thorax trauma-related complications (eg, acute respiratory distress syndrome [ARDS]), total hospital stay, and mortality.

RESULTS

Of the 516 patients included in the study, 140 (27%) developed thorax-related complications. The overall in-hospital mortality rate was 10%. The receiver operating characteristic curve for predicting mortality demonstrated an adequate discrimination by a value of 0.844. The TTSS was statistically significant higher in patients who died of thorax-related complications than in patients who died because of nonthorax-related complications and survivors (P < 0.001, confidence interval [CI] 95%). In patients who developed ARDS the TTSS was significant higher (P = 0.005, CI 95%).

CONCLUSION

This study supports the use of the TTSS for predicting mortality in thoracic injury patients. Furthermore, the TTSS appears capable of predicting ARDS.

Post injury multiple organ failure

The understanding of post injury multiple organ failure (MOF) has evolved considerably since it was first described more than 30 years ago. Improved trauma care has decreased the mortality of single organ injury, although these patients may go on to MOF. There has been significant investigation in both the basic science and clinical understanding of MOF. This research has altered management strategies thereby decreasing the incidence and mortality related to MOF. Despite this MOF remains the greatest contributor to late trauma death and morbidity. This review defines essential terminology, examines the historical perspective of MOF, describes common scoring systems, describes the changes in epidemiology, discusses the aetiology and pathophysiology, reviews current prevention, resuscitation and treatment strategies and provides future direction for research.

Impact of plasma transfusion in trauma patients who do not require massive transfusion

BACKGROUND

For trauma patients requiring massive blood transfusion, aggressive plasma usage has been demonstrated to confer a survival advantage. The aim of this study was to evaluate the impact of plasma administration in nonmassively transfused patients.

STUDY DESIGN

Trauma patients admitted to a Level I trauma center (2000-2005) requiring a nonmassive transfusion (<10 U packed RBC [PRBC] within 12 hours of admission) were identified retrospectively. Propensity scores were calculated to match and compare patients receiving plasma in the first 12 hours with those who did not.

RESULTS

The 1,716 patients (86.1% of 1,933 who received PRBC transfusion) received a nonmassive transfusion. After exclusion of 31 (1.8%) early deaths, 284 patients receiving plasma were matched to patients who did not. There was no improvement in survival with plasma transfusion (17.3% versus 14.1%; p = 0.30) irrespective of the plasma-to-PRBC ratio achieved. However, the overall complication rate was significantly higher for patients receiving plasma (26.8% versus 18.3%, odds ratio [OR] = 1.7; 95% CI, 1.1-2.4; p = 0.016). As the volume of plasma increased, an increase in complications was seen, reaching 37.5% for patients receiving >6 U. The ARDS rate specifically was also significantly higher in patients receiving plasma (9.9% versus 3.5%, OR = 3.0; 95% CI, 1.4-6.2; p = 0.004]. Patients receiving >6 U plasma had a 12-fold increase in ARDS, a 6-fold increase in multiple organ dysfunction syndrome, and a 4-fold increase in pneumonia and sepsis.

CONCLUSIONS

For nonmassively transfused trauma patients, plasma administration was associated with a substantial increase in complications, in particular ARDS, with no improvement in survival. An increase in multiple organ dysfunction, pneumonia, and sepsis was likewise seen as increasing volumes of plasma were transfused. The optimal trigger for initiation of a protocol for aggressive plasma infusion warrants prospective evaluation.

Pathophysiology, management and treatment of smoke inhalation injury

Smoke inhalation injury continues to increase morbidity and mortality in burn patients in both the third world and industrialized countries. The lack of uniform criteria for the diagnosis and definition of smoke inhalation injury contributes to the fact that, despite extensive research, mortality rates have changed little in recent decades. The formation of reactive oxygen and nitrogen species, as well as the procoagulant and antifibrinolytic imbalance of alveolar homeostasis, all play a central role in the pathogenesis of smoke inhalation injury. Further hallmarks include massive airway obstruction owing to cast formation, bronchospasm, the increase in bronchial circulation and transvascular fluid flux. Therefore, anticoagulants, antioxidants and bronchodilators, especially when administered as an aerosol, represent the most promising treatment strategies. The purpose of this review article is to provide an overview of the pathophysiological changes, management and treatment options of smoke inhalation injury based on the current literature.

A 6-year review of total parenteral nutrition use and association with late-onset acute respiratory distress syndrome among ventilated trauma victims

AIM

To establish whether total parenteral nutrition (TPN) for ventilated trauma victims is associated with late-onset acute respiratory distress syndrome (ARDS) independent of ventilation and transfusion parameters.

METHOD

Intensive care unit data over 6 years from a level I centre regarding all trauma victims > or = 16 years old who underwent mechanical ventilation within the first 48 h of admission were examined. Patients were prospectively followed for late ARDS. Variables were examined for significant changes over time and independent associations with late ARDS were determined.

RESULTS

Of 2346 eligible patients among whom 404 (17.2%) were exposed to TPN, 192 (8.2%) met criteria for late ARDS. The incidence of late ARDS among those exposed to TPN was 28.7% (116/404) compared with 3.9% (76/1942) among those not so exposed. Adjustments for potential confounding associated risk factors were made.

CONCLUSIONS

TPN administration is independently associated with late ARDS, and its use among critically ill trauma victims should be carefully scrutinised.

Fluid resuscitation in the trauma patient

Trauma is responsible for 25% of all emergency department visits causing a healthcare burden of more than $400 billion a year. Timely and appropriate fluid resuscitation may mean the difference between survival and death. Controversy surrounds the best method of fluid resuscitation for optimum recovery. This article will evaluate current research regarding the various types of fluid resuscitation in the trauma population. Colloid and crystalloid fluid will be compared describing the risks and benefits of each.

Increased plasma and platelet to red blood cell ratios improves outcome in 466 massively transfused civilian trauma patients

OBJECTIVE

To determine the effect of blood component ratios in massive transfusion (MT), we hypothesized that increased use of plasma and platelet to red blood cell (RBC) ratios would result in decreased early hemorrhagic death and this benefit would be sustained over the ensuing hospitalization.

SUMMARY BACKGROUND DATA

Civilian guidelines for massive transfusion (MT > or =10 units of RBC in 24 hours) have typically recommend a 1:3 ratio of plasma:RBC, whereas optimal platelet:RBC ratios are unknown. Conversely, military data shows that a plasma:RBC ratio approaching 1:1 improves long term outcomes in MT combat casualties. There is little consensus on optimal platelet transfusions in either civilian or military practice. At present, the optimal combinations of plasma, platelet, and RBCs for MT in civilian patients is unclear.

METHODS

Records of 467 MT trauma patients transported from the scene to 16 level 1 trauma centers between July 2005 and June 2006 were reviewed. One patient who died within 30 minutes of admission was excluded. Based on high and low plasma and platelet to RBC ratios, 4 groups were analyzed.

RESULTS

Among 466 MT patients, survival varied by center from 41% to 74%. Mean injury severity score varied by center from 22 to 40; the average of the center means was 33. The plasma:RBC ratio ranged from 0 to 2.89 (mean +/- SD: 0.56 +/- 0.35) and the platelets:RBC ratio ranged from 0 to 2.5 (0.55 +/- 0.50). Plasma and platelet to RBC ratios and injury severity score were predictors of death at 6 hours, 24 hours, and 30 days in multivariate logistic models. Thirty-day survival was increased in patients with high plasma:RBC ratio (> or =1:2) relative to those with low plasma:RBC ratio (<1:2) (low: 40.4% vs. high: 59.6%, P < 0.01). Similarly, 30-day survival was increased in patients with high platelet:RBC ratio (> or =1:2) relative to those with low platelet:RBC ratio (<1:2) (low: 40.1% vs. high: 59.9%, P < 0.01). The combination of high plasma and high platelet to RBC ratios were associated with decreased truncal hemorrhage, increased 6-hour, 24-hour, and 30-day survival, and increased intensive care unit, ventilator, and hospital-free days (P < 0.05), with no change in multiple organ failure deaths. Statistical modeling indicated that a clinical guideline with mean plasma:RBC ratio equal to 1:1 would encompass 98% of patients within the optimal 1:2 ratio.

CONCLUSIONS

Current transfusion practices and survival rates of MT patients vary widely among trauma centers. Conventional MT guidelines may underestimate the optimal plasma and platelet to RBC ratios. Survival in civilian MT patients is associated with increased plasma and platelet ratios. Massive transfusion practice guidelines should aim for a 1:1:1 ratio of plasma:platelets:RBCs.

Anemia, transfusions and hospital outcomes among critically ill patients on prolonged acute mechanical ventilation: a retrospective cohort study

INTRODUCTION

Patients requiring prolonged acute mechanical ventilation (PAMV) represent one-third of those who need mechanical ventilation, but they utilize two-thirds of hospital resources devoted to mechanical ventilation. Measures are needed to optimize the efficiency of care in this population. Both duration of intensive care unit stay and mechanical ventilation are associated with anemia and increased rates of packed red blood cell (pRBC) transfusion. We hypothesized that transfusions among patients receiving PAMV are common and associated with worsened clinical and economic outcomes.

METHODS

A retrospective analysis of a large integrated claims database covering a 5-year period (January 2000 to December 2005) was conducted in adult patients receiving PAMV (mechanical ventilation for >/= 96 hours). The incidence of pRBC transfusions was examined as the main exposure variable, and hospital mortality served as the primary outome, with hospital length of stay and costs being secondary outcomes.

RESULTS

The study cohort included 4,344 hospitalized patients receiving PAMV (55% male, mean age 61.5 +/- 16.4 years). Although hemoglobin level upon admission was above 10 g/dl in 75% of patients, 67% (n = 2,912) received at least one transfusion, with a mean of 9.1 +/- 12.0 units of pRBCs transfused per patient over the course of hospitalization. In regression models adjusting for confounders, exposure to pRBCs was associated with a 21% increase in the risk for hospital death (95% confidence interval [CI] = 1.00 to 1.48), and marginal increases in length of stay (6.3 days, 95% CI = 5.1 to 7.6) and cost ($48,972, 95% CI = $45,581 to $52,478).

CONCLUSION

Patients receiving PAMV are at high likelihood of being transfused with multiple units of blood at relatively high hemoglobin levels. Transfusions independently contribute to increased risk for hospital death, length of stay, and costs. Reducing exposure of PAMV patients to blood may represent an attractive target for efforts to improve quality and efficiency of health care delivery in this population.