Adult respiratory distress syndrome risk factors for injured patients undergoing damage-control laparotomy: AAST multicenter post hoc analysis

Hemodynamic resuscitation with fluids bolus and norepinephrine increases severity of lung damage in an experimental model of septic shock

OBJECTIVE

Hemodynamic resuscitation is considered a cornerstone of the initial treatment of septic shock. However, there is growing concern about its side effects. Our objective was to assess the relationship between fluid administration and norepinephrine infusion and the development of lung injury.

DESIGN

Randomized in vivo study in rabbits.

SETTING

University animal research laboratory.

PATIENTS

Eighteen New Zealand rabbits. Control group (SHAM, n=6), Sepsis group with or without hemodynamic resuscitation (ETX-R, n=6; ETX-NR, n=6).

INTERVENTIONS

Sepsis was induced by intravenous lipopolysaccharide administration and animals were followed-up for 4h. Hemodynamic resuscitation with Ringer lactate (20mL·kg^-1) was administered and later norepinephrine was initiated 3h after sepsis induction. At the end, the left lung was excised.

MAIN VARIABLES OF INTEREST

An indwelling arterial catheter and an esophageal Doppler were placed. Lung mechanics were monitored with side stream spirometry. Lung damage was analyzed by histopathological examination.

RESULTS

The SHAM group did not show hemodynamic or respiratory changes. Lipopolysaccharide administration aimed an increase in cardiac output and arterial hypotension. In the ETX-NR group, animals remained hypotensive until the end of the experiment. Resuscitation with fluids and norepinephrine reversed arterial hypotension. Compared to the ETX-NR group, the remaining lung of the ETX-R group showed greater accumulation of neutrophils and reactive type-II pneumocytes, thicker alveolar wall, alveolar hemorrhage and non-aerated pulmonary areas. Lung injury score was larger in the ETX-R group.

CONCLUSIONS

In our experimental study, following a strategy with bolus fluids and late norepinephrine used in the early phase of endotoxic septic shock has a negative influence on the development of lung injury.

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.

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.

Hemodynamic resuscitation with fluids bolus and norepinephrine increases severity of lung damage in an experimental model of septic shock

OBJECTIVE

Hemodynamic resuscitation is considered a cornerstone of the initial treatment of septic shock. However, there is growing concern about its side effects. Our objective was to assess the relationship between fluid administration and norepinephrine infusion and the development of lung injury.

DESIGN

Randomized in vivo study in rabbits.

SETTING

University animal research laboratory.

PATIENTS

Eighteen New Zealand rabbits. Control group (SHAM, n=6), Sepsis group with or without hemodynamic resuscitation (ETX-R, n=6; ETX-NR, n=6).

INTERVENTIONS

Sepsis was induced by intravenous lipopolysaccharide administration and animals were followed-up for 4h. Hemodynamic resuscitation with Ringer lactate (20mL·kg-1) was administered and later norepinephrine was initiated 3h after sepsis induction. At the end, the left lung was excised.

MAIN VARIABLES OF INTEREST

An indwelling arterial catheter and an esophageal Doppler were placed. Lung mechanics were monitored with side stream spirometry. Lung damage was analyzed by histopathological examination.

RESULTS

The SHAM group did not show hemodynamic or respiratory changes. Lipopolysaccharide administration aimed an increase in cardiac output and arterial hypotension. In the ETX-NR group, animals remained hypotensive until the end of the experiment. Resuscitation with fluids and norepinephrine reversed arterial hypotension. Compared to the ETX-NR group, the remaining lung of the ETX-R group showed greater accumulation of neutrophils and reactive type-II pneumocytes, thicker alveolar wall, alveolar hemorrhage and non-aerated pulmonary areas. Lung injury score was larger in the ETX-R group.

CONCLUSIONS

In our experimental study, following a strategy with bolus fluids and late norepinephrine used in the early phase of endotoxic septic shock has a negative influence on the development of lung injury.

Is chest imaging relevant in diagnosing acute respiratory distress syndrome in polytrauma patients? A population-based cohort study

Purpose

The definition of acute respiratory distress syndrome (ARDS) has often been modified with Berlin criteria being the most recent. ARDS is divided into three categories based on the degree of hypoxemia using PaO₂/FiO₂ ratio. Radiological findings are standardized with bilateral diffuse pulmonary infiltrates present on chest imaging. This study investigated whether chest imaging is relevant in diagnosing ARDS in polytrauma patients.

Methods

The 5-year prospective study included consecutive trauma patients admitted to a Level-1 Trauma Center ICU. Demographics, ISS, physiologic parameters, resuscitation parameters, and ARDS data were prospectively collected. Acute hypoxic respiratory failure (AHRF) was categorized as Berlin criteria without bilateral diffuse pulmonary infiltrates on imaging. Data are presented as median (IQR), p < 0.05 was considered significant.

Results

267 patients were included. Median age was 45 (26–59) years, 199 (75%) males, ISS was 29 (22–35), 258 (97%) patients had blunt injuries. Thirty-five (13%) patients died. 192 (72%) patients developed AHRF. AHRF patients were older, more often male, had higher ISS, needed more crystalloids and blood products than patients without AHRF. They developed more pulmonary complications, stayed longer on the ventilator, in ICU and in hospital, and died more often. Fifteen (6%) patients developed ARDS. There was no difference in outcome between ARDS and AHRF patients.

Conclusions

Many patients developed AHRF and only a few ARDS. Patients with similar hypoxemia without bilateral diffuse pulmonary infiltrates had comparable outcome as ARDS patients. Chest imaging did not influence the outcome. Large-scale multicenter validation of ARDS criteria is warranted to investigate whether diffuse bilateral pulmonary infiltrates on chest imaging could be omitted as a mandatory part of the definition of ARDS in polytrauma patients.

Electronic supplementary material

The online version of this article (10.1007/s00068-019-01204-3) contains supplementary material, which is available to authorized users.

Incidence of acute respiratory distress syndrome and associated mortality in a polytrauma population

Background

The incidence of acute respiratory distress syndrome (ARDS) has decreased in the last decade by improvement in trauma and critical care. However, it still remains a major cause of morbidity and mortality. This study investigated the current incidence and mortality of ARDS in polytrauma patients.

Methods

A 4.5-year prospective study included consecutive trauma patients admitted to a level 1 trauma center intensive care unit (ICU). Isolated head injuries, drowning, asphyxiation, burns, and deaths <48 hours were excluded. Demographics, Injury Severity Score (ISS), physiologic parameters, resuscitation parameters, Denver Multiple Organ Failure scores, and ARDS data according to Berlin criteria were prospectively collected. Data are presented as median (IQR), and p<0.05 was considered significant.

Results

241 patients were included. The median age was 45 (27–59) years, 178 (74%) were male, the ISS was 29 (22–36), and 232 (96%) patients had blunt injuries. Thirty-one patients (13%) died. Fifteen patients (6%) developed ARDS. The median time to ARDS onset was 3 (2–5) days after injury. The median duration of ARDS was 2.5 (1–3.5) days. All patients with ARDS were male compared with 61% of non-ARDS patients (p=0.003). Patients who developed ARDS had higher ISS (30 vs. 25, p=0.01), lower Partial Pressure of Oxygen in arterial blood (PaO₂₎ both in the emergency department and ICU, and higher Partial Pressure of Carbon Dioxide in arterial blood (PaCo₂) in the ICU. Patients with ARDS needed more crystalloids <24 hours (8.7 vs. 6.8 L, p=0.03), received more fresh frozen plasma <24 hours (3 vs. 0 U, p=0.04), and more platelet <8 hours and <24 hours. Further, they stayed longer on the ventilator (11 vs. 2 days, p<0.001), longer in the ICU (12 vs. 3 days, p<0.001), and in the hospital (33 vs. 15 days, p=0.004). Patients with ARDS developed more often multiple organ dysfunction syndrome (40% vs. 3%, p<0.001) and died more often (20% vs. 3%, p=0.01). Only one patient with ARDS (7%) died of ARDS.

Discussion

In this polytrauma population mortality was predominantly caused by brain injury. The incidence of ARDS was low; its presentation was only early onset, during a short time period, and accompanied by low mortality.

Level of evidence

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.

Mild to Moderate to Severe: What Drives the Severity of ARDS in Trauma Patients?

Acute respiratory distress syndrome (ARDS) is a complex inflammatory process with multifactorial etiologies. Risk factors for its development have been extensively studied, but factors associated with worsening severity of disease, as defined by the Berlin criteria, are poorly understood. A retrospective chart and trauma registry review identified trauma patients in our surgical intensive care unit who developed ARDS, defined according to the Berlin definition, between 2010 and 2015. The primary outcome was development of mild, moderate, or severe ARDS. A logistic regression model identified risk factors associated with developing ARDS and with worsening severity of disease. Of 2704 total patients, 432 (16%) developed ARDS. Of those, 100 (23%) were categorized as mild, 176 (41%) as moderate, and 156 (36%) as severe. Two thousand two hundred and seventy-two patients who did not develop ARDS served as controls. Male gender, blunt trauma, severe head and chest injuries, and red blood cell as well as total blood product transfusions are independent risk factors associated with ARDS. Worsening severity of disease is associated with severe chest trauma and volume of plasma transfusion. Novel findings in our study include the association between plasma transfusions and specifically severe chest trauma with worsening severity of ARDS in trauma patients.

Permissive Hypotension and Trauma: Can Fluid Restriction Reduce the Incidence of ARDS?

Emergency care, including the resuscitation of patients involved in traumatic events, has evolved over the years. A prior practice of utilizing large volumes of crystalloids has been found to contribute to complications such as coagulopathy, fluid overload, and adult respiratory distress syndrome (ARDS). In contrast, permissive hypotension is a method of fluid restriction that allows for low blood pressure and mean arterial pressure during the resuscitation period. When permissive hypotension occurs and fluids are restricted in trauma patients, the incidence of ARDS can be reduced significantly with improvement in patient outcomes. Using evidence, nurse practitioners in the emergency department have an important role in evaluating and updating protocols such as permissive hypotension.

Open abdomen critical care management principles: resuscitation, fluid balance, nutrition, and ventilator management

The term "open abdomen" refers to a surgically created defect in the abdominal wall that exposes abdominal viscera. Leaving an abdominal cavity temporarily open has been well described for several indications, including damage control surgery and abdominal compartment syndrome. Although beneficial in certain patients, the act of keeping an abdominal cavity open has physiologic repercussions that must be recognized and managed during postoperative care. This review article describes these issues and provides guidelines for the critical care physician managing a patient with an open abdomen.

Treatments and other prognostic factors in the management of the open abdomen: A systematic review

BACKGROUND

The open abdomen (OA) is an important approach for managing intra-abdominal catastrophes and continues to be the standard of care. Despite this, challenges remain with it associated with a high incidence of complications and poor outcomes. The objective of this article is to perform a systematic review in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines to identify prognostic factors in OA patients in regard to definitive fascial closure (DFC), mortality and intra-abdominal complications.

METHODS

An electronic database search was conducted involving Medline, Excerpta Medica, Central Register of Controlled Trials, Cumulative Index to Nursing, and Allied Health Literature and Clinicaltrials.gov. All studies that described prognostic factors in regard to the above outcomes in OA patients were eligible for inclusion. Data collected were synthesized by each outcome of interest and assessed for methodological quality.

RESULTS

Thirty-one studies were included in the final synthesis. Enteral nutrition, organ dysfunction, local and systemic infection, number of reexplorations, worsening Injury Severity Score, and the development of a fistula appeared to significantly delay DFC. Age and Adult Physiology And Chronic Health Evaluation version II score were predictors for in-hospital mortality. Failed DFC, large bowel resection and >5 to 10 L of intravenous fluids in <48 hours were predictors of enteroatmospheric fistula. The source of infection (small bowel as opposed to colon) was a predictor for ventral hernia. Large bowel resection, >5 to 10 and >10 L of intravenous fluids in <48 hours were predictors of intra-abdominal abscess. Fascial closure on (or after) day 5 and having a bowel anastomosis were predictors for anastomotic leak. Overall methodological quality was of a moderate level.

LIMITATIONS

Overall methodological quality, high number of retrospective studies, low reporting of prognostic factors and the multitude of factors potentially affecting patient outcome that were not analyzed.

CONCLUSION

Careful selection and management of OA patients will avoid prolonged treatment and facilitate early DFC. Future research should focus on the development of a prognostic model.

LEVEL OF EVIDENCE

Systematic review, 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.

Perioperative "remote" acute lung injury: recent update

Perioperative acute lung injury (ALI) is a syndrome characterised by hypoxia and chest radiograph changes. It is a serious post-operative complication, associated with considerable mortality and morbidity. In addition to mechanical ventilation, remote organ insult could also trigger systemic responses which induce ALI. Currently, there are limited treatment options available beyond conservative respiratory support. However, increasing understanding of the pathophysiology of ALI and the biochemical pathways involved will aid the development of novel treatments and help to improve patient outcome as well as to reduce cost to the health service. In this review we will discuss the epidemiology of peri-operative ALI; the cellular and molecular mechanisms involved on the pathological process; the clinical considerations in preventing and managing perioperative ALI and the potential future treatment options.

Preemptive hemodynamic intervention restricting the administration of fluids attenuates lung edema progression in oleic acid-induced lung injury

OBJECTIVE

A study is made of the influence of preemptive hemodynamic intervention restricting fluid administration upon the development of oleic acid-induced lung injury.

DESIGN

A randomized in vivo study in rabbits was carried out.

SETTING

University research laboratory.

SUBJECTS

Sixteen anesthetized, mechanically ventilated rabbits.

VARIABLES

Hemodynamic measurements obtained by transesophageal Doppler signal. Respiratory mechanics computed by a least square fitting method. Lung edema assessed by the ratio of wet weight to dry weight of the right lung. Histological examination of the left lung.

INTERVENTIONS

Animals were randomly assigned to either the early protective lung strategy (EPLS) (n=8) or the early protective hemodynamic strategy (EPHS) (n=8). In both groups, lung injury was induced by the intravenous infusion of oleic acid (OA) (0.133mlkg^-1h^-1 for 2h). At the same time, the EPLS group received 15mlkg^-1h^-1 of Ringer lactate solution, while the EPHS group received 30mlkg^-1h^-1. Measurements were obtained at baseline and 1 and 2h after starting OA infusion.

RESULTS

After 2h, the cardiac index decreased in the EPLS group (p<0.05), whereas in the EPHS group it remained unchanged. Lung compliance decreased significantly only in the EPHS group (p<0.05). Lung edema was greater in the EPHS group (p<0.05). Histological damage proved similar in both groups (p=0.4).

CONCLUSIONS

In this experimental model of early lung injury, lung edema progression was attenuated by preemptively restricting the administration of fluids.