Incidence Of Acute Respiratory Distress Syndrome Research Articles

Prevention of acute respiratory distress syndrome.

The paucity of effective therapeutic interventions in patients with the acute respiratory distress syndrome (ARDS) combined with overwhelming evidence on the importance of timely implementation of effective therapies to critically ill patients has resulted in a recent shift in ARDS research. Increasingly, efforts are being directed toward early identification of patients at risk with a goal of prevention and early treatment, prior to development of the fully established syndrome. The focus of the present review is on the prevention of ARDS in patients without this condition at the time of their healthcare encounter. The primary thematic categories presented in the present review article include early identification of patients at risk of developing ARDS, optimization of care delivery and its impact on the incidence of ARDS, pharmacological prevention of ARDS, prevention of postoperative ARDS, and challenges and opportunities with ARDS prevention studies. Recent improvements in clinical care delivery have been associated with a decrease in the incidence of hospital-acquired ARDS. Despite the initial challenges, research in ARDS prevention has become increasingly feasible with several randomized controlled trials on ARDS prevention completed or on the way.

High Tidal Volume Decreases Adult Respiratory Distress Syndrome, Atelectasis, and Ventilator Days Compared with Low Tidal Volume in Pediatric Burned Patients with Inhalation Injury

Inhalation injury, which is among the causes of acute lung injury and acute respiratory distress syndrome (ARDS), continues to represent a significant source of mortality in burned patients. Inhalation injury often requires mechanical ventilation, but the ideal tidal volume strategy is not clearly defined in burned pediatric patients. The aim of this study was to determine the effects of low and high tidal volume on the number of ventilator days, ventilation pressures, and incidence of atelectasis, pneumonia, and ARDS in pediatric burned patients with inhalation injury within 1 year post burn injury. From 1986 to 2014, inhalation injury was diagnosed by bronchoscopy in pediatric burned patients (n = 932). Patients were divided into 3 groups: unventilated (n = 241), high tidal volume (HTV, 15 ± 3 mL/kg, n = 190), and low tidal volume (LTV, 9 ± 3 mL/kg, n = 501). High tidal volume was associated with significantly decreased ventilator days (p < 0.005) and maximum positive end expiratory pressure (p < 0.0001) and significantly increased maximum peak inspiratory pressure (p < 0.02) and plateau pressure (p < 0.02) compared with those in patients with LTV. The incidence of atelectasis (p < 0.0001) and ARDS (p < 0.02) was significantly decreased with HTV compared with LTV. However, the incidence of pneumothorax was significantly increased in the HTV group compared with the LTV group (p < 0.03). High tidal volume significantly decreases ventilator days and the incidence of both atelectasis and ARDS compared with low tidal volume in pediatric burned patients with inhalation injury. Therefore, the use of HTV may interrupt sequences leading to lung injury in our patient population.

49 Lung Protective Ventilation is Uncommon During Aeromedical Transport: An Observational Study

Mechanical ventilation is common during aeromedical transport, and emerging data suggests that routine application of low-tidal volume lung protective ventilation may decrease complications of critical illness. This study was designed to describe mechanical ventilation practices for intubated patients transported by air ambulance and to assess the effect of mechanical ventilation strategy on clinical outcomes. Our hypotheses were (1) lung protective ventilation would be uncommon in the out-of-hospital setting, (2) out-of-hospital ventilation practices would influence initial ventilator management in the hospital, and (3) non-lung protective ventilation would increase the incidence of acute respiratory distress syndrome (ARDS). Retrospective, observational cohort study of all adult patients transported by a university-affiliated aeromedical transport service to a 711-bed tertiary academic medical center (July 2011 to May 2013). Patients were excluded for (1) death within 72 hours of hospital arrival or (2) admission to an outside hospital prior to transfer. Data was collected on ventilator settings and clinical outcomes from the electronic medical record. Univariate descriptive analyses were performed and linear regression was used to test the hypothesis that hospital ventilation strategy was influenced by out-of-hospital ventilation settings. The association between lung protective ventilation and clinical outcomes was measured with a logistic regression model. Lung protective ventilation was defined a priori as ≤ 8 mL/kg predicted body weight (PBW). The Institutional Review Board approved the study under waiver of informed consent. A total of 235 patients were included in the analysis. The majority of patients (57%) were ventilated solely with bag-valve ventilation during transport. The mean tidal volume of mechanically ventilated patients was 8.6 mL/kg PBW (SD 1.7 ml/kg PBW). Lung-protective ventilation was used in 13% of patients (n= 31). Patients receiving non-protective ventilation during aeromedical transport were significantly more likely to be exposed to non-protective ventilation in the emergency department (P<0.001) and intensive care unit (P=0.015). Out-of-hospital lung-protective ventilation was associated with a decrease in mechanical ventilation days (2.1 versus 3.6 day, P=0.027), but there was no association with the incidence of ARDS, length of stay, or mortality. Low tidal volume ventilation was rare during aeromedical transport and was associated with a “therapeutic momentum” of non-lung protective ventilation during early in-hospital care. Prehospital tidal volumes were associated with a decrease in mechanical ventilation days, but not associated with development of ARDS or mortality. The out-of-hospital aeromedical environment offers a unique opportunity to study the impact of early prophylactic therapies on complications of critical illness, and further study is needed to better characterize the role of lung protective ventilation on ARDS prevention.

Replacement of anesthesia machines improves intraoperative ventilation parameters associated with the development of acute respiratory distress syndrome

BackgroundThe impact of anesthetic equipment on clinical practice parameters associated with development of acute respiratory distress syndrome (ARDS) has not been extensively studied. We hypothesized a change in anesthesia machines would be associated with parameters associated with lower rates of ARDS.MethodsWe performed a retrospective cohort study on a subset of data used to evaluate intraoperative ventilation. Patients included adults receiving a non-cardiac, non-thoracic, non-transplant, non-trauma, general anesthetic between 2/1/05, and 3/31/09 at the University of Michigan. Existing anesthesia machines (Narkomed IIb, Drager) were exchanged for new equipment (Aisys, General Electric). The initial subset compared the characteristics of patients anesthetized between 12/1/06 and 1/31/07 (pre) with those between 4/1/07 and 5/30/07 (post). An extended subset examined cases two years pre and post exchange. Using the standard predicted body weight (PBW), we calculated and compared the tidal volume (total Vt and mL/kg PBW) as well as positive end-expiratory pressure (PEEP), peak inspiratory pressure (PIP), Delta P (PIP-PEEP), and FiO2.ResultsA total of 1,414 patients were included in the 2-month pre group and 1,635 patients included in the post group. Comparison of ventilation characteristics found statistically significant differences in median (pre v post): PIP (26 ± 6 v 21 ± 6 cmH2O,p < .001), Delta P (24 ± 6 v 19 ± 6 cmH2O, p < .001), Vt (588 ± 139 v 562 ± 121 ml, p < 0.001; 9.3 ± 2.2 v 9.0 ± 1.9 ml/kg predicted body weight, p < .001), FiO2 (0.57 ± 0.17 v 0.52 ± 0.18, p < .001). Groups did not differ in age, ASA category, PBW, or BMI. The two year subgroup had similar parameters. Risk adjustment resulted in minimal differences in the analysis. New anesthesia machines were associated with a non-statistically significant reduction in postoperative ARDS.ConclusionsIn this study, a change in ventilator management was associated with an anesthesia machine exchange. The smaller Vt and lower PIP noted in the post group may imply a lower risk of volutrauma and barotrauma, which may be significant in at-risk populations. However, there was not a statistically significant reduction in the incidence of post-operative ARDS.

ABSTRACT 481

Background and aims: The most accepted definition for acute respiratory distress syndrome (ARDS) remains the American-European Consensus Conference (AECC) definition. Other proposed definitions include the Berlin definition, SpO2:FiO2 ratio (S/F ratio), oxygenation index (OI), and oxygenation saturation index (OSI). Aims: Our aim is to compare these definitions with regard to reclassification of children with ARDS. Methods: We identified patients with ARDS (based on AECC’s definition) between 2009 and 2012. The Institutional Review Board approved this study. The following cutoffs were used.Table: No title available.Results: 26 patients were identified. ARDS incidence was 6.3/1000 of PICU admissions. Median age was 8.3years (4 days-17 years). Median PRISM2 score was 6.4 (0.7–86.3). Overall mortality was 62%. 51 arterial blood gas and saturation readings were analyzed. The Berlin definition for moderate-severe ARDS did not change any classification. On day 1, the S/F ratio identified all cases of ALI and ARDS but the OI and OSI reclassified one and two patients from ARDS to ALI respectively. On day 2, S/F ratio, OI and OSI reclassified two patients with normal P/F ratios into either ALI or ARDS. These patients were on excessively high FiO2. Conclusions: AECC and Berlin definition identified the same patients. SpO2 based markers overestimate lung injury when excessively high FiO2 is used. Further studies on these definitions are needed.

ABSTRACT 497

Background and aims: Acute respiratory distress syndrome (ARDS) is one of the important diseases in children. Aims: The purpose of this study was to determine the incidence, cause, prognostic factors, and outcome of ARDS in children. Methods: We conducted a retrospective medical-chart review of children diagnosed with ARDS at the PICU of the Seoul St. Mary’s Hospital, Catholic University of Korea from March 2009 to February 2012. Results: Out of the 334 children admitted to the PICU, 19 (5.6%) were diagnosed with ARDS as per the criteria stated by the American-European Consensus Conference (AECC). Thirteen ARDS patients died, and the mortality rate was 68.4%. Pneumonia was the most common cause of ARDS in 7 (36.7%) cases. The mortality rate of patients with a baseline PaO2/FiO2 value of ≤100 mmHg was significantly higher than that of patients with a baseline PaO2/FiO2 value >100 mmHg (84.6% vs. 33.3%; P = 0.046). During their stay in the PICU, we observed that higher the number of failing organs, higher was the mortality rate (P = 0.037). Conclusions: The ARDS mortality rate in children was 68.4 %, which was higher than that observed in other studies conducted within as well as outside the country. The PaO2/FiO2 ratio at ARDS onset and the number of failing organs during PICU stay were prognostic factors that aided in the determination of the ARDS mortality rate in children.

Síndrome de distrés respiratorio agudo: revisión a propósito de la definición de Berlín

Acute Respiratory Distress Syndrome (ARDS) is due to many causes. The absence of a universal definition up until now has led to a series of practical problems for a definitive diagnosis. The incidences of ARDS and Acute Lung Injury (ALI) vary widely in the current literature. The American-European Consensus Conference definition has been applied since its publication in 1994 and has helped to improve knowledge about ARDS. However, 18 years later, in 2011, the European Intensive Medicine Society, requested a team of international experts to meet in Berlin to review the ARDS definition. The purpose of the Berlin definition is not to use it as a prognostic tool, but to improve coherence between research and clinical practice.

The acute respiratory distress syndrome

The purpose of this review is to examine and discuss the incidence and outcome of patients with the acute respiratory distress syndrome (ARDS). This is a challenging task, as there is no specific clinical sign or diagnostic test that accurately identifies and adequately defines this syndrome. This review will focus on published epidemiological studies reporting population-based incidence of ARDS, as defined by the American-European Consensus Conference criteria. In addition, the current outcome figures for ARDS patients reported in observational and randomized controlled trials will be reviewed. The focus will be on studies published since 2000, when the ARDSnet study on protective mechanical ventilation was published, although particular emphasis will be on those articles published in the last 24 months. On the basis of current evidence, and despite the order of magnitude of reported European and USA incidence figures, it seems that the incidence and overall mortality of ARDS has not changed substantially since the original ARDSnet study. The current mortality of adult ARDS is still greater than 40%.

Postoperative Acute Respiratory Distress Syndrome in Patients With Previous Exposure to Bleomycin

To determine the incidence and risk factors for postoperative acute respiratory distress syndrome (ARDS) in a large cohort of bleomycin-exposed patients undergoing surgery with general endotracheal anesthesia. From a Mayo Clinic cancer registry, we identified patients who had received systemic bleomycin and then underwent a major surgical procedure that required more than 1 hour of general anesthesia from January 1, 2000, through August 30, 2012. Heart, lung, and liver transplantations were excluded. Postoperative ARDS (within 7 days after surgery) was defined according to the Berlin criteria. We identified 316 patients who underwent 541 major surgical procedures. Only 7 patients met the criteria for postoperative ARDS; all were white men, and 6 were current or former smokers. On univariate analysis, we observed an increased risk of postoperative ARDS in patients who were current or former smokers. Furthermore, significantly greater crystalloid and colloid administration was found in patients with postoperative ARDS. We also observed a trend toward longer surgical duration and red blood cell transfusion in patients with postoperative ARDS, although this finding was not significant. Intraoperative fraction of inspired oxygen was not associated with postoperative ARDS. In bleomycin-exposed patients, the incidence of postoperative ARDS after major surgery with general anesthesia is approximately 1.3% (95% CI, 0.6%-2.6%). For first major procedures after bleomycin therapy, the incidence is 1.9% (95% CI, 0.9%-4.1%). The risk of postoperative ARDS in patients exposed to systemic bleomycin appears to be lower than expected. Smoking status may be an important factor that modifies the risk of postoperative ARDS in these patients.

Incidence of acute lung injury in dogs receiving transfusions

To document the existence and incidence of acute lung injury (ie, veterinary acute lung injury [VetALI] per the 2007 consensus definition) in a population of client-owned dogs receiving transfusions for various clinical reasons. Prospective observational study. 54 client-owned dogs. Arterial blood gas analysis was performed for dogs receiving a transfusion (blood and plasma products) at 0 to 12 hours before and 24 to 48 hours after transfusion; dogs also underwent thoracic radiography 0 to 24 hours before and 24 to 48 hours after transfusion. The ratio of PaO2 to fraction of inspired oxygen (FIO2) was calculated. Dogs with posttransfusion radiographic signs of pulmonary infiltrates, a PaO2:FIO2 ratio < 300, or clinical signs of respiratory compromise were suspected of having VetALI and underwent echocardiography to exclude left-sided heart failure. The incidence of VetALI was calculated, and χ(2) tests were used to compare the incidence in study dogs with the historical reported incidence of acute respiratory distress syndrome (ARDS) in ill dogs (not receiving transfusions) and transfusion-related acute lung injury (TRALI) in humans. The incidence of VetALI (2/54 [3.7%]; 95% confidence interval, 0% to 8.73%) in study dogs was significantly less than the reported incidence of TRALI in humans (25%) and not significantly different from the reported incidence of ARDS in ill dogs (10%). VetALI occurred in dogs that received transfusions at a frequency similar to that previously reported for ARDS in ill dogs that did not receive transfusions.

Incidence and outcome of acute lung injury and acute respiratory distress syndrome in the surgical intensive care unit.

Introduction:To determine the incidence and mortality of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) in a cohort of patients with risk factors admitted to the Surgical Intensive Care Unit (SICU).Materials and Methods:A prospective observational inception cohort study with no intervention was conducted over 12 months. All patients with at least one known risk factor for ALI/ARDS admitted to the SICU were included in the study. The APACHE II severity of disease classification system scoring was performed within 1 h of admission. The ventilatory parameters and chest radiographs were recorded every 24 h. The P/F ratio, PEEP and Lung Injury Score were calculated each day until the day of discharge from the Intensive Care Unit or for the first 7 days of admission, whichever was shorter.Results:The incidence of ARDS among those who were mechanically ventilated was 11.4%. Sepsis was the most common (34.6%) etiology. Among those with risk factors, the incidence of ARDS was 30% and that of ALI was 32.7%. The mortality in those with ARDS was 41.8%. Those who develop ARDS had higher APACHE II scores, lower pH and higher PaCO2 at admission compared with those who developed ALI or no lung injury.Conclusion:The incidence and mortality of ARDS was similar to other studies. Identifying those with risk factors for ARDS or mortality will enable appropriate interventional measures.

Efficacy of glucocorticoids for treatment of severe acute pancreatitis: a meta analysis

Objective To evaluate the efficacy of glucocorticoids in treatment of patients with severe acute pancreatitis(SAP).Methods According to the inclusion criteria,the experimental design,characteristics of the included objects,and the corresponding outcomes were extracted from relevant literatures.Meta-analysis was done to evaluate the results by RevMan 5.1software.Results A total of eight articles with 184cases in this treatment group and 177participants in the control group were included in this meta-analysis.Data from six studies showed that the mortality rate of glucocorticoid group(14/145,9. 655%)was significantly lower than that of the control group(28/139,20.14%),with the difference being statistically significant(OR=0.42,95% CI[0.21-0.83],P=0.01).Data from three studies showed that the frequency of acute respiratory distress syndrome(ARDS)of the glucocorticoid group(20/95,21.05%)was significantly lower than that of the control group(37/89,41.57%,OR=0.33,95% CI[0.16-0.65],P=0.001).Data from three studies showed that the operation transferring rate in the glucocorticoid group(12/87,13.79%)was significantly lower than that of control group(26/ 81,32.09%,OR=0.29,95% CI[0.13-0.67],P=0.004).Compared with the control group,the glucocorticoid group also had significantly reduced the mean hospital stay in four experiments(standardized mean difference-1.52,95% CI[-2.73--0.32],P=0.01).Conclusion Glucocorticoid has advantages over conventional treatments in reducing the incidence of ARDS and mortality and shortening hospital stay in SAP patients,which provides a new and prospective therapeutic option for SAP.

Designing a Better “Nest”

Designing a Better “Nest”

Use of Plasmapheresis in the Enzymatic Phase of Severe Acute Pancreatitis

Objective: to evaluate the efficiency of early plasmapheresis in the enzymatic phase of severe acute pancreatitis. Patient characteristics and methods. Thirteen 25-to-86-year-old patients diagnosed with severe acute pancreatitis (SAP) were examined and treated at the intensive care unit of the military hospital (Sergiev Posad) in 2011—2012. The patients underwent comprehensive clinical, laboratory, and instrumental examinations. Their clinical and laboratory parameters were analyzed at admission, before and after extracorporeal detoxification. The exfused plasma level of pancreatic enzymes was studied. The admission patient status was assessed using the APACHE II; the severity of the disease was evaluated employing the Glasgow and Ranson pancreatic scales; the Murray scale was used to estimate the degree of acute lung lesion. During the prospective study, there were 2 patient groups: 1) 7 patients who underwent extracorporeal detoxification in early-stage disease (on days 1—2); 2) 6 patients received infusion therapy with forced diuresis elements as detoxification measures (a comparison group). The incidence of acute respiratory distress syndrome (ARDS), pancreatic tissue destruction, and pyoseptic complications and intensive care unit stay and hospital length of stay, and mortality were comparatively analyzed. Results. The investigation demonstrated that there were reductions in the incidence of ARDS by 35.7%, pancreatic destruction by 35.7%, and pyoseptic complications by 16.7% and in the intensive care unit stay and hospital length of stay by 42.9 and 31.2%, respectively, and in mortality rates by 16.7% in Group 1 compared to Group 2. Conclusion. The use of plasmapheresis to treat early-stage SAP assists in reducing the magnitude of enzymatic toxemia due to the direct elimination of pancreatic enzymes from systemic circulation. This sanogenic effect can offset the aggressive effect of hyper-enzymia and hence prevent ARDS even in severe baseline disease. Early plasmapheresis allows the results of intensive therapy for SAP to be improved. Key words: severe acute pancreatitis, acute respiratory distress syndrome, plasmapheresis.

Adult Respiratory Distress Syndrome Following Cardiac Surgery

Severe lung injury with the development of acute respiratory distress syndrome (ARDS) is a serious complication of cardiac surgery. The aim of this study was to determine the incidence, risk factors, and mortality of ARDS following cardiac surgery. We retrospectively analyze data in the period between January 2005 and March 2013. Of 6069 patients who underwent cardiac surgery during the study period, 37 patients developed ARDS during the postoperative period. The incidence of ARDS was 0.61%, with a mortality of 40.5% (15 patients). Multivariate regression analysis identified previous cardiac surgery, complex cardiac surgery, and more than three transfusions with packed red blood cells (PRBC) were independent predictors for developing ARDS. ARDS remains a serious, but very rare complication associated with significant mortality. In our study, previous cardiac surgery, complex cardiac surgery, and more than three transfusions of PRBC were independent predictors for the development of ARDS.

The Epidemiology of Acute Respiratory Distress Syndrome in Patients Presenting to the Emergency Department With Severe Sepsis

Acute respiratory distress syndrome (ARDS) is a serious complication of sepsis, and sepsis-associated ARDS is associated with significant morbidity and mortality. To date, no study has directly examined the epidemiology of ARDS in severe sepsis from the earliest presentation to the health care system, the emergency department (ED). This was a single-center retrospective, observational cohort study of 778 adults with severe sepsis presenting to the ED. The primary outcome was the development of ARDS requiring mechanical ventilation during the first 5 hospital days. Acute respiratory distress syndrome was defined using the Berlin definition. We used multivariable logistic regression to identify risk factors associated independently with ARDS development. The incidence of ARDS was 6.2% (48/778 patients) in the entire cohort. Acute respiratory distress syndrome development varied across the continuum of care: 0.9% of patients fulfilled criteria for ARDS in the ED, 1.4% admitted to the ward developed ARDS, and 8.9% admitted to the intensive care unit developed ARDS. Acute respiratory distress syndrome developed a median of 1 day after admission and was associated with a 4-fold higher risk of in-hospital mortality (14% vs. 60%, P < 0.001). Independent risk factors associated with increased risk of ARDS development included intermediate (2-3.9 mmol/L) (P = 0.04) and high (≥4) serum lactate levels (P = 0.008), Lung Injury Prediction score (P < 0.001), and microbiologically proven infection (P = 0.01). In patients presenting to the ED with severe sepsis, the rate of sepsis-associated ARDS development varied across the continuum of care. Acute respiratory distress syndrome developed rapidly and was associated with significant mortality. Elevated serum lactate levels in the ED and a recently validated clinical prediction score were independently associated with the development of ARDS in severe sepsis.

Airway Pressure Release Ventilation Prevents Ventilator-Induced Lung Injury in Normal Lungs

Up to 25% of patients with normal lungs develop acute lung injury (ALI) secondary to mechanical ventilation, with 60% to 80% progressing to acute respiratory distress syndrome (ARDS). Once established, ARDS is treated with mechanical ventilation that can paradoxically elevate mortality. A ventilation strategy that reduces the incidence of ARDS could change the clinical paradigm from treatment to prevention. To demonstrate that (1) mechanical ventilation with tidal volume (VT) and positive end-expiratory pressure (PEEP) settings used routinely on surgery patients causes ALI/ARDS in normal rats and (2) preemptive application of airway pressure release ventilation (APRV) blocks drivers of lung injury (ie, surfactant deactivation and alveolar edema) and prevents ARDS. Rats were anesthetized and tracheostomy was performed at State University of New York Upstate Medical University. Arterial and venous lines, a peritoneal catheter, and a rectal temperature probe were inserted. Animals were randomized into 3 groups and followed up for 6 hours: spontaneous breathing ventilation (SBV, n = 5), continuous mandatory ventilation (CMV, n = 6), and APRV (n = 5). Rats in the CMV group were ventilated with Vt of 10 cc/kg and PEEP of 0.5 cm H2O. Airway pressure release ventilation was set with a P(High) of 15 to 20 cm H2O; P(Low) was set at 0 cm H2O. Time at P(High) (T(High)) was 1.3 to 1.5 seconds and a T(Low) was set to terminate at 75% of the peak expiratory flow rate (0.11-0.14 seconds), creating a minimum 90% cycle time spent at P(High). Bronchoalveolar lavage fluid and lungs were harvested for histopathologic analysis at necropsy. Acute lung injury/ARDS developed in the CMV group (mean [SE] PaO2/FiO2 ratio, 242.96 [24.82]) and was prevented with preemptive APRV (mean [SE] PaO2/FIO2 ratio, 478.00 [41.38]; P < .05). Airway pressure release ventilation also significantly reduced histopathologic changes and bronchoalveolar lavage fluid total protein (endothelial permeability) and preserved surfactant proteins A and B concentrations as compared with the CMV group. Continuous mandatory ventilation in normal rats for 6 hours with Vt and PEEP settings similar to those of surgery patients caused ALI. Preemptive application of APRV blocked early drivers of lung injury, preventing ARDS. Our data suggest that APRV applied early could reduce the incidence of ARDS in patients at risk.

An attempt to validate the modification of the American-European consensus definition of acute lung injury/acute respiratory distress syndrome by the Berlin definition in a university hospital

The Berlin definition for acute respiratory distress syndrome (ARDS) is a new proposal for changing the American-European consensus definition but has not been assessed prospectively as yet. In the present study, we aimed to determine (1) the prevalence and incidence of ARDS with both definitions, and (2) the initial characteristics of patients with ARDS and 28-day mortality with the Berlin definition. We performed a 6-month prospective observational study in the ten adult ICUs affiliated to the Public University Hospital in Lyon, France, from March to September 2012. Patients under invasive or noninvasive mechanical ventilation, with PaO2/FiO2 <300 mmHg regardless of the positive end-expiratory pressure (PEEP) level, and acute onset of new or increased bilateral infiltrates or opacities on chest X-ray were screened from ICU admission up to discharge. Patients with cardiogenic pulmonary edema were excluded. Patients were further classified into specific categories by using the American-European Consensus Conference and the Berlin definition criteria. The complete data set was measured at the time of inclusion. Patient outcome was measured at day 28 after inclusion. During the study period 3,504 patients were admitted and 278 fulfilled the American-European Consensus Conference criteria. Among them, 18 (6.5 %) did not comply with the Berlin criterion PEEP ≥ 5 cmH2O and 20 (7.2 %) had PaO2/FiO2 ratio ≤200 while on noninvasive ventilation. By using the Berlin definition in the remaining 240 patients (n = 42 mild, n = 123 moderate, n = 75 severe), the overall prevalence was 6.85 % and it was 1.20, 3.51, and 2.14 % for mild, moderate, and severe ARDS, respectively (P > 0.05 between the three groups). The incidence of ARDS amounted to 32 per 100,000 population per year, with values for mild, moderate, and severe ARDS of 5.6, 16.3, and 10 per 100,000 population per year, respectively (P < 0.05 between the three groups). The 28-day mortality was 35.0 %. It amounted to 30.9 % in mild, 27.9 % in moderate, and 49.3 % in severe categories (P < 0.01 between mild or moderate and severe, P = 0.70 between mild and moderate). In the Cox proportional hazard regression analysis ARDS stage was not significantly associated with patient death at day 28. The present study did not validate the Berlin definition of ARDS. Neither the stratification by severity nor the PaO2/FiO2 at study entry was independently associated with mortality.

Impact of High Ratios of Plasma–to–Red Cell Concentrate on the Incidence of Acute Respiratory Distress Syndrome in UK Transfused Combat Casualties

Trauma transfusion strategies, which incorporate balanced red-cell concentrate (RCC)-to-fresh frozen plasma (FFP) ratios, may be associated with improved survival in massively transfused patients. However, the use of this approach in nonmassively transfused patients has led to concern regarding an increase in acute respiratory distress syndrome (ARDS). The aim of this study was to assess the incidence of ARDS in transfused UK military casualties. All UK military casualties receiving an RCC transfusion within a 16-month period were identified from the UK Trauma Registry, and chest radiographs retrieved. If bilateral infiltrates were present, case notes were retrieved to calculate the PaO2/FIO2 ratio in accordance with the American-European Consensus Conference criteria. Patients were divided into massively transfused (≥ 10 U/24 h) and nonmassively transfused (<10 U/24 h) receiving a high ratio (≥ 0.75) or low (<0.75) RCC:FFP ratio. The primary outcome was the development of ARDS within 7 days of transfusion. Primary blast lung injury was excluded. Of 145 patients identified, 144 had records available for analysis with a median injury severity score of 21. The majority were injured by explosion (76%), and the remainder by gunshot (24%). There were 60 nonmassively transfused patients with 18 in the low and 42 in the high RCC:FFP ratio groups. Of the remaining 80 massively transfused patients, 11 were in the low and 73 were in the high-ratio groups. There was no difference in the incidence of ARDS between low- and high-ratio groups in either nonmassively transfused (22.2% vs. 9.5%; P = 0.232) or massively transfused (18.2% vs. 23.3%; P = 1.000) casualties. There was no statistically significant increase in the incidence of ARDS in UK casualties treated with high, compared with low, ratios of plasma to RCC.

Predicting postoperative pulmonary complications in high-risk populations

Our objective is to describe prediction models for surgical patients who have suspected obstructive sleep apnea (OSA) at risk for postoperative respiratory complications and for surgical patients at risk for postoperative acute respiratory distress syndrome (ARDS). Because of the increased rate of severe perioperative respiratory complications in patients with OSA, the American Society of Anesthesiologists issued practice guidelines for perioperative management. When OSA is diagnosed preoperatively, the rate of postoperative pulmonary complications is low and not associated with OSA severity. However, OSA continues to be an important risk because a substantial proportion of patients in the contemporary surgical population have undiagnosed OSA. Strategies based on preoperative and immediate postoperative clinical signs and symptoms can help identify patients with a high likelihood of OSA, postoperative desaturations, and pulmonary complications. ARDS is another serious postoperative complication associated with high mortality rate and limited treatment options, and its prevention is critical. Practice changes have led to a dramatic reduction in ARDS incidence. A recently developed prediction model can help identify high-risk patients. Evidence is emerging that early identification of modifiable risk factors and implementation of 'protective' management strategies may lead to reduction of severe postoperative pulmonary complications.