Fluid management in acute respiratory distress syndrome

Perioperative fluid management for lung transplantation is challenging

Lung transplantation is the definitive end-stage treatment for many lung diseases, and postoperative pulmonary oedema severely affects survival after lung transplantation. Optimizing perioperative fluid management can reduce the incidence of postoperative pulmonary oedema and improve the prognosis of lung transplant patients by removing the influence of patient, donor's lung and ECMO factors. Therefore, this article reviews seven aspects of lung transplant patients' pathophysiological characteristics, physiological characteristics of fluids, the influence of the donor lung on pulmonary oedema as well as current fluid rehydration concepts, advantages or disadvantages of intraoperative monitoring tools or types of fluids on postoperative pulmonary oedema, while showing the existing challenges in section 7. The aim is to show the specificity of perioperative fluid management in lung transplant patients and to provide new ideas for individualised fluid management in lung transplantation.

The Association Between Extravascular Lung Water and Critical Care Outcomes Following Bilateral Lung Transplantation

Primary graft dysfunction (PGD) is a form of acute respiratory failure that complicates 30% of bilateral lung transplants. Higher grades of PGD correlate with higher severity of respiratory failure and unfavorable outcomes. Immediate PGD determination posttransplant‚ however, is not always predictive of PGD over subsequent days or intensive care unit outcomes. We aimed to evaluate whether extravascular lung water index (ELWI) measured immediately post bilateral lung transplant was associated with higher severity of PGD at 72 h and duration of mechanical ventilation.

Predictive value of computed tomography for short-term mortality in patients with acute respiratory distress syndrome: a systematic review

The best available evidence and the predictive value of computed tomography (CT) findings for prognosis in patients with acute respiratory distress syndrome (ARDS) are unknown. We systematically searched three electronic databases (MEDLINE, CENTRAL, and ClinicalTrials.gov). A total of 410 patients from six observational studies were included in this systematic review. Of these, 143 patients (34.9%) died due to ARDS in short-term. As for CT grade, the CTs used ranged from 4- to 320-row. The index test included diffuse attenuations in one study, affected lung in one study, well-aerated lung region/predicted total lung capacity in one study, CT score in one study and high-resolution CT score in two studies. Considering the CT findings, pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio were 62% (95% confidence interval [CI] 30–88%), 76% (95% CI 57–89%), 2.58 (95% CI 2.05–2.73), 0.50 (95% CI 0.21–0.79), and 5.16 (95% CI 2.59–3.46), respectively. This systematic review revealed that there were major differences in the definitions of CT findings, and that the integration of CT findings might not be adequate for predicting short-term mortality in ARDS. Standardisation of CT findings and accumulation of further studies by CT with unified standards are warranted.

The Effect of Loop Diuretics on 28-Day Mortality in Patients With Acute Respiratory Distress Syndrome

Background: Diuretics have been widely used in critically ill patients while it remains uncertain whether they can reduce mortality in patients with acute respiratory distress syndrome (ARDS). This study aimed to investigate the associations between diuretics and 28-day mortality in patients with ARDS.

Methods: This is a secondary analysis of the ARDS Network Fluid and Catheter Treatment Trial (FACTT) of National Heart, Lung, and Blood Institute. Those patients who did not receive renal replacement therapy within the first 48 h after enrollment in the FACTT were included in the analysis. A marginal structural Cox model (MSCM) was used to investigate the associations between diuretics and 28-day mortality after correction of both the baseline and time-varying variables. The latent class analysis (LCA) and subgroup analysis were performed to identify the kind of patients that could be benefited from diuretics.

Results: A total of 932 patients were enrolled, i.e., 558 patients in the diuretics group and 374 patients in the no diuretics group within the first 48 h. The 28-day mortality was lower in the diuretics group (15.1 vs. 28.1%, p < 0.001). In MSCM, diuretics use was related to the improved 28-day mortality (HR 0.78; 95% CI 0.62–0.99; p = 0.04). LCA identified three subtypes, and diuretics were associated with reduced mortality in subtype 3, which was characterized by worse renal function and higher central venous pressure (CVP). A subgroup analysis indicated survival advantage among the female patients, sepsis induced ARDS, and those with the ratio of partial pressure of oxygen to the fractional concentration of inspired oxygen (PaO₂/FiO₂) ≤ 150 mmHg, and mean arterial pressure (MAP) ≥ 65 mmHg.

Conclusion: Loop diuretics were associated with the reduced 28-day mortality in the patients with ARDS, after controlling for time-varying confounders. Randomized trials are required to verify the association.

Effect of N-Acetylcysteine on the treatment of acute respiratory distress syndrome in mechanically ventilated patients admitted to the intensive care unit

Background: N-acetylcysteine (NAC) is an antioxidant derived from the amino acid cysteine and is one of the drugs used in the treatment of respiratory diseases. The aim of this study was to investigate the effect of NAC on the treatment of acute respiratory distress syndrome in mechanically ventilated patients admitted to the intensive care unit. Methods: This study was a randomized clinical trial. Patients under mechanical ventilation admitted to the intensive care unit were examined. Patients in the intervention group received daily 150 mg/kg of NAC on the first day of admission and then 50 mg/kg up to the fourth day of admission. Patients in the control group received routine care. The vital signs, level of consciousness, and other important variables were recorded. Data were analyzed using statistical tests and SPSS software version 24. Results: There was no significant difference between MAP, heart rate, respiratory rate, O2Sat, APACHE II score, and pulmonary capacity of the patients in the two groups on the first, second, third and fourth days after the intervention (p>0.05 ). There was no significant difference between the level of consciousness (according to GCS criteria), respiratory index (PAO2/FIO2) and PEEP of patients in the two study groups within 1 to 2 days after the intervention (p>0.05). There was a significant difference between the level of consciousness (based on GCS criteria), respiratory index (PAO2/FIO2) and PEEP of patients in the two study groups within 3 to 4 days after the intervention (p<0.05). There was no significant difference between the duration of hospitalization in the ICU, the time required for mechanical ventilation and the mortality rate of the patients in the two groups (p>0.05). Conclusion: It seems that N-acetylcysteine has a positive effect on the treatment of acute respiratory distress syndrome in mechanically ventilated patients admitted to the intensive care unit.

Fluid administration and monitoring in ARDS: which management?

Modalities of fluid management in patients sustaining the acute respiratory distress syndrome (ARDS) are challenging and controversial. Optimal fluid management should provide adequate oxygen delivery to the body, while avoiding inadvertent increase in lung edema which further impairs gas exchange. In ARDS patients, positive fluid balance has been associated with prolonged mechanical ventilation, longer ICU and hospital stay, and higher mortality. Accordingly, a restrictive strategy has been compared to a more liberal approach in randomized controlled trials conducted in various clinical settings. Restrictive strategies included fluid restriction guided by the monitoring of extravascular lung water, pulmonary capillary wedge or central venous pressure, and furosemide targeted to diuresis and/or albumin replacement in hypoproteinemic patients. Overall, restrictive strategies improved oxygenation significantly and reduced duration of mechanical ventilation, but had no significant effect on mortality. Fluid management may require different approaches depending on the time course of ARDS (i.e., early vs. late period). The effects of fluid strategy management according to ARDS phenotypes remain to be evaluated. Since ARDS is frequently associated with sepsis-induced acute circulatory failure, the prediction of fluid responsiveness is crucial in these patients to avoid hemodynamically inefficient—hence respiratory detrimental—fluid administration. Specific hemodynamic indices of fluid responsiveness or mini-fluid challenges should be preferably used. Since the positive airway pressure contributes to positive fluid balance in ventilated ARDS patients, it should be kept as low as possible. As soon as the hemodynamic status is stabilized, correction of cumulated fluid retention may rely on diuretics administration or renal replacement therapy.

Paralytics, Sedation, and Steroids in Acute Respiratory Distress Syndrome

In this article, we discuss the literature behind the use of paralytics, sedation, and steroids in acute respiratory distress syndrome. We explore the controversies and discuss the recommendations for the use of these agents.

Fluid management in Acute Respiratory Distress Syndrome: A narrative review

Acute Respiratory Distress Syndrome remains a major source of morbidity and mortality in the modern intensive care unit (ICU). Major advances in the understanding and management of this condition were made in the last two decades. The use of low tidal ventilation is a well-established therapy. Conservative fluid management is now another cornerstone of management. However, much remains to be understood in this arena. Assessing volume status in these patients may be challenging and the tools available to do so are far from perfect. Several dynamic measures including pulse pressures variation are used. Ultrasound of the lungs and the vascular system may also have a role. In addition, the type of fluid to administer when needed is still open to debate. Finally, supportive measures in these patients, early during their ICU stay and later after discharge continue to be crucial for survival and adequate recovery.

Effects of propofol pretreatment on lung morphology and heme oxygenase-1 expression in oleic acid-induced acute lung injury in rats

PURPOSE

To investigate the effects of propofol pretreatment on lung morphology and heme oxygenase-1 expression in oleic acid -induced acute lung injury in rats.

METHODS

A total of 32 male Sprague-Dawley rats (250-300g) were randomly divided into the following four groups (n=8/group): group C, group OA, group OA+PR, and group OA+IX to compare related parameter changes.

RESULTS

PaO2, PCO2, and PaO2/FiO2 were significantly different among the four treatment groups (P<0.05 or P<0.01). Lung wet/dry weight ratio and HO-1 protein expression also significantly differed among the groups (P<0.01). Immunohistochemistry showed that the expression of HO-1 in group OA+PR was stronger than those in groups OA, OA+IX, and C. Light microscopy revealed that pathological changes in lung tissues in group OA+PR were milder than those in group OA and group OA+IX. Electron microscopy showed that alveolar type II epithelial cell ultrastructure in group OA was relatively irregular with cell degeneration and disintegration and cytoplasmic lamellar bodies were vacuolized. Changes in group OA+PR were milder than those in group OA; however, they were more severe in group OA+IX than in group OA.

CONCLUSION

Propofol significantly increases the expression of HO-1 in the lung tissueand prevents changes in lung morphology due to ALI in rats.

Effects of N-acetylcysteine treatment in acute respiratory distress syndrome: A meta-analysis

Acute respiratory distress syndrome (ARDS) is a serious complication of acute lung injury. Severe systemic inflammation is the main cause of multiple organ dysfunction and high mortality. Removal of reactive oxygen species by anti-oxidants has been applied in clinical practice. N-acetylcysteine (NAC) is the most commonly used anti-oxidant. However, the benefit of anti-oxidant therapy was not consistently demonstrated by previous studies. In the present study, a meta-analysis was performed to evaluate the effects of NAC for adult patients with ARDS. The PubMed, Cochrane and EMBASE databases were searched to retrieve all of the available randomized controlled trials (RCTs) published until October 2015. Quality evaluation of included studies was performed according to the modified Jadad scale score. The Cochrane Collaboration Review Manager 5.3 software was used to perform the meta-analysis. Five RCTs comprising 183 patients were found to be eligible for inclusion in the meta-analysis. Pooled analysis showed that NAC did not contribute to reduce short-term mortality [risk ratio (RR)=0.73; 95% confidence interval (CI): 0.50–1.07; P=0.10] or 30-day mortality (RR=0.72; 95% CI: 0.44–1.19; P=0.20) when compared with those in the control group. However, duration of intensive care unit (ICU) stay in the NAC group was shortened [weighted mean difference (WMD), −4.56; 95% CI: (−7.32 to −1.80); P=0.001]. There was no significant difference in the ratio of partial arterial oxygen pressure to the fraction of inspired oxygen between the two groups [WMD, 54.34; 95% CI: (−30.50 to 139.17); P=0.21]. No severe adverse reactions were observed in the patients included. Although the duration of ICU stay was shortened, the clinical benefits of NAC were limited for ARDS based on the present meta-analysis. As the number of included trials and patients was small, additional trials are required to provide sufficient evidence for the efficacy of NAC in ARDS.

Pulmonary Arterial Compliance in Acute Respiratory Distress Syndrome: Clinical Determinants and Association With Outcome From the Fluid and Catheter Treatment Trial Cohort

OBJECTIVES

Pulmonary vascular dysfunction is associated with adverse prognosis in patients with the acute respiratory distress syndrome; however, the prognostic impact of pulmonary arterial compliance in acute respiratory distress syndrome is not established.

DESIGN, SETTING, PATIENTS

We performed a retrospective analysis of 363 subjects with acute respiratory distress syndrome who had complete baseline right heart catheterization data from the Fluid and Catheter Treatment Trial to test whether pulmonary arterial compliance at baseline and over the course of treatment predicted mortality.

MAIN RESULTS

Baseline pulmonary arterial compliance (hazard ratio, 1.18 per interquartile range of 1/pulmonary arterial compliance; 95% CI, 1.02-1.37; p = 0.03) and pulmonary vascular resistance (hazard ratio, 1.28 per interquartile range; 95% CI, 1.07-1.53; p = 0.006) both modestly predicted 60-day mortality. Baseline pulmonary arterial compliance remained predictive of mortality when pulmonary vascular resistance was in the normal range (p = 0.02). Between day 0 and day 3, pulmonary arterial compliance increased in acute respiratory distress syndrome survivors and remained unchanged in nonsurvivors, whereas pulmonary vascular resistance did not change in either group. The resistance-compliance product (resistance-compliance time) increased in survivors compared with nonsurvivors, suggesting improvements in right ventricular load.

CONCLUSIONS

Baseline measures of pulmonary arterial compliance and pulmonary vascular resistance predict mortality in acute respiratory distress syndrome, and pulmonary arterial compliance remains predictive even when pulmonary vascular resistance is normal. Pulmonary arterial compliance and right ventricular load improve over time in acute respiratory distress syndrome survivors. Future studies should assess the impact of right ventricular protective acute respiratory distress syndrome treatment on right ventricular afterload and outcome.

Changes in B-type Natriuretic Peptide and Related Hemodynamic Parameters Following a Fluid Challenge in Critically Ill Patients with Severe Sepsis or Septic Shock

CONTEXT

Severe sepsis or septic shock.

AIMS

The aim of this study is to examine the effect of a fluid challenge on the B-type natriuretic peptide (BNP) and the hemodynamic state.

SETTINGS AND DESIGN

This observational study was conducted in an intensivist-led academic, mixed medical-surgical Intensive Care Unit.

SUBJECTS AND METHODS

Focused transthoracic echocardiogram, plasma BNP, and hemodynamic measurements were recorded at baseline and following a 500 ml fluid challenge in thirty patients. Independent predictors of the percentage (%) change in stroke volume (SV) were sought. Next, these independent predictors were assessed for a relationship with the percentage change in BNP.

STATISTICAL ANALYSIS USED

Multiple linear regressions, Wilcoxon rank-sum test, t-test, and Pearson's correlation were used. Data analysis was carried out using SAS. The 5% significance level was used.

RESULTS

Using a multiple regression models, the percentage increase in SV was independently predicted by the percentage increase in mean arterial pressure, left ventricular end-diastolic volume/dimension (LVEDV/LVEDd), ejection fraction, and a decrease in Acute Physiology and Chronic Health Evaluation II score (P < 0.0001). Preload, measured using LVEDV1 (before the fluid challenge) was significantly larger in the fluid nonresponders (%SV increase <15%) vs. the responders (%SV increase ≥15%). Finally, the percentage change in BNP was positively correlated with left ventricular size at end diastole LVEDd, r = 0.4, P < 0.035).

CONCLUSIONS

An increase in BNP soon after a fluid challenge may have some predictive utility of a large LVEDd, which in turn can be used to independently predict the SV response to a fluid challenge.

Management of blunt pulmonary injury

Thoracic injuries account for 25% of all civilian deaths. Blunt force injuries are a subset of thoracic injuries and include injuries of the tracheobronchial tree, pleural space, and lung parenchyma. Early identification of these injuries during initial assessment and resuscitation is essential to reduce associated morbidity and mortality rates. Management of airway injuries includes definitive airway control with identification and repair of tracheobronchial injuries. Management of pneumothorax and hemothorax includes pleural space drainage and control of ongoing hemorrhage, along with monitoring for complications such as empyema and chylothorax. Injuries of the lung parenchyma, such as pulmonary contusion, may require support of oxygenation and ventilation through both conventional and nonconventional mechanical ventilation strategies. General strategies to improve pulmonary function and gas exchange include balanced fluid resuscitation to targeted volume-based resuscitation end points, positioning therapy, and pain management.

Na/K-ATPase assay in the intact mice lung subjected to perfusion

BACKGROUND

Among the characteristics of acute respiratory distress syndrome (ARDS) is edema formation and its resolution depends on pneumocyte Na/K-ATPase activity. Increased concentration of oleic acid (OA) in plasma induces lung injury by targeting Na/K-ATPase and, thus, interfering in sodium transport.

FINDINGS

Presently, we adapted a radioactivity-free assay to detect Na/K-ATPase activity in perfused lung mice, comparing the inhibitory effect of ouabain and OA. We managed to perfuse only the lung, avoiding the systemic loss of rubidium. Rb+ incorporation into lung was measured by inductively coupled plasma optical emission spectrometry (ICP OES) technique, after lung tissue digestion. Na/K-ATPase activity was the difference between Rb+ incorporation with or without ouabain. Lung Na/K-ATPase was completely inhibited by perfusion with ouabain. However, OA caused a partial inhibition.

CONCLUSIONS

In the present work the amount of incorporated Rb+ was greater than seen in our previous report, showing that the present technique is trustworthy. This new proposed assay may allow researchers to study the importance of Na/K-ATPase activity in lung pathophysiology.

Venovenous extracorporeal life support for posttraumatic respiratory distress syndrome in adults: the risk of major hemorrhages

Background

The aim of this retrospective study is to investigate the therapeutic benefits and the bleeding risks of venovenous extracorporeal life support (VV-ECLS) when used for adult posttraumatic respiratory distress syndrome (posttraumatic ARDS).

Materials and methods

Twenty adult trauma patients (median age: 38 years, median injury severity score: 35) treated with VV-ECLS in a level I trauma center between January 2004 and June 2013 were enrolled in this study. The indication of VV-ECLS for posttraumatic ARDS was refractory hypoxemia (P_aO₂/F_iO₂ ratio ≤ 70 mmHg) under advanced mechanical ventilation. To minimize potential complications, a protocol-guided VV-ECLS was adopted.

Results

Sixteen patients were weaned off VV-ECLS, and of these patients fourteen survived. Medians of the trauma-to-ECLS time, the pre-ECLS mechanical ventilation, and the ECLS duration in all patients were 64, 45, and 144 hours respectively. The median P_aO₂/F_iO₂ ratio was improved significantly soon after VV-ECLS, from 56 to 106 mmHg (p < 0.001). However, seven major hemorrhages occurred during VV-ECLS, of which three were lethal. The multivariate analysis revealed that the occurrence of major hemorrhages during VV-ECLS was independently related to the trauma-to-ECLS time < 24 hours (OR: 20; p = 0.02; 95% CI: 2–239; c-index: 0.81).

Conclusions

Despite an effective respiratory support, VV-ECLS should be cautiously administered to patients who develop advanced ARDS soon after major trauma.

Electronic supplementary material

The online version of this article (doi:10.1186/s13049-014-0056-0) contains supplementary material, which is available to authorized users.

Management of Blunt Pulmonary Injury

Thoracic injuries account for 25% of all civilian deaths. Blunt force injuries are a subset of thoracic injuries and include injuries of the tracheobronchial tree, pleural space, and lung parenchyma. Early identification of these injuries during initial assessment and resuscitation is essential to reduce associated morbidity and mortality rates. Management of airway injuries includes definitive airway control with identification and repair of tracheobronchial injuries. Management of pneumothorax and hemothorax includes pleural space drainage and control of ongoing hemorrhage, along with monitoring for complications such as empyema and chylothorax. Injuries of the lung parenchyma, such as pulmonary contusion, may require support of oxygenation and ventilation through both conventional and nonconventional mechanical ventilation strategies. General strategies to improve pulmonary function and gas exchange include balanced fluid resuscitation to targeted volume-based resuscitation end points, positioning therapy, and pain management.

Act fast and ventilate soft: the Düsseldorf hands-on translation of the acute respiratory distress syndrome Berlin definition

Early identification of acute respiratory distress syndrome (ARDS) and forceful implementation of standardized therapy algorithms are the mandatory basis of an effective therapy to improve patient outcome. Recently, a new definition of ARDS was implemented, which simplified the diagnostic criteria for ARDS. Evidence-based therapies are rare, but some cornerstone interventions can be recommended. Lung-protective ventilation with high positive end-expiratory pressure and low tidal volume and early prone positioning in severe cases improve survival rate. We here present an integrated "Düsseldorf hands-on translation" in the form of a "one-page" standard operating procedure in order to fasten and standardize both diagnosis and therapeutic algorithms on an intensive care unit.

Human adult bone marrow-derived stem cells decrease severity of lipopolysaccharide-induced acute respiratory distress syndrome in sheep

INTRODUCTION

Acute respiratory distress syndrome (ARDS) is the most common cause of respiratory failure among critically ill subjects, sepsis and severe bacterial pneumonia being its most common causes. The only interventions that have proven beneficial are protective ventilation strategies and fluid conservation approaches. New therapies are needed to address this common clinical problem. Others and we have previously shown the beneficial effect of infusion of exogenous adult stem cells in different pre-clinical models of ARDS.

METHODS

In the present study endotoxin was infused intravenously into 14 sheep from which 6 received different doses of adult stem cells by intrabronchial delivery to evaluate the effect of stem cell therapy.

RESULTS

After administration of endotoxin, there was a rapid decline in oxygenation to hypoxemic values, indicative of severe-to-moderate ARDS. None of the animals treated with saline solution recovered to normal baseline values during the 6 hours that the animals were followed. In contrast, sheep treated with a dose of 40 million adult stem cells returned their levels of oxygen in their blood to baseline two hours after the cells were infused. Similarly, improvements in carbon dioxide (CO2) clearance, pulmonary vascular pressures and inflammation were observed and confirmed by histology and by the decrease in lung edema.

CONCLUSIONS

We concluded that instillation of adult non-hematopoietic stem cells can diminish the impact of endotoxin and accelerate recovery of oxygenation, CO2 removal and inflammation in the ovine model, making the use of adult stem cells a real alternative for future therapies for ARDS.

Oleic acid inhibits lung Na/K-ATPase in mice and induces injury with lipid body formation in leukocytes and eicosanoid production

BACKGROUND

Acute respiratory distress syndrome (ARDS) can emerge from certain pathologies, such as sepsis, fat embolism and leptospirosis, in which the levels of unesterified fatty acids are increased in the patient's plasma. ARDS is characterized by edema formation, and edema resolution occurs mainly due to the pneumocyte Na/K-ATPase activity. As previously described, increased oleic acid (OA) plasma concentrations induce lung injury by interfering with sodium transport. The first aim of this study was to develop a radioactivity-free assay to detect Na,K-ATPase activity ex vivo using a model of OA-induced lung injury in mice. We also investigated the relationship between Na/K-ATPase inhibition and OA-induced lung injury using ouabain-induced lung injury as a comparison, because of the well-described effect of ouabain as a Na/K-ATPase inhibitor.

METHODS

We developed a Na/K-ATPase assay based on the capture of non-radioactive Rb+ ions by mice lung tissue in the absence or presence of ouabain, a specific Na/K-ATPase inhibitor. Rb+ incorporation into the lung was measured by inductively coupled plasma-optical emission spectrometry (ICP-OES) after lung tissue mineralization. Na/K-ATPase activity was considered as the difference between Rb+ incorporation in the absence and in the presence of ouabain. Bronchoalveolar lavage fluid was collected for lung injury assessment. For this assessment, cell counting, lipid body enumeration and lipid mediator concentrations were measured. Histological analyses were used to determinate lung pathology. Whole body plethysmographic analysis was performed to assay lung function.

RESULTS

The lung Na/K-ATPase activity of mice was completely inhibited by an OA dose of 10 μmol, an effect also obtained with 10-3 μmol of ouabain, as demonstrated by the decreased Rb+ incorporation in the lungs. The same OA dose induced lung edema and inflammation with cell influx, lipid body formation, and leukotriene B4 (LTB4) and prostaglandin E2 (PGE2) production. Ouabain also induced lung inflammation, as detected by histological examinations. As far as we know, this is the first time that ouabain-induced lung injury was shown. Both OA and ouabain induced functional lung pathology in mice simultaneously with inhibition of the lung Na/K-ATPase activity.

CONCLUSIONS

We developed a new non-radioactive assay to quantified Na/K-ATPase in vivo. OA and ouabain inhibited in vivo Na/K-ATPase activity in the lungs and induced lung injury. Our data reinforce the idea that Na/K-ATPase inhibitors may worsen lung injury in specific pathological conditions.