Conservative Fluid Management Strategy Research Articles

A Comprehensive Review of the Management of Acute Respiratory Distress Syndrome.

Acute respiratory distress syndrome (ARDS) is an inflammatory process in the lungs that induces non-hydrostatic protein-rich pulmonary edema.ARDS occurs in roughly halfof coronavirus disease 2019 (COVID-19) pneumonia patients, with most of them requiring intensive care. Oxygen saturation, partial pressure of the oxygen, and the fraction of the inspired oxygen are health indicators that may indicate a severe illnessnecessitating further investigation.As treatments have evolved, a typical pattern of ARDS has likewise evolved. In cases where mechanical ventilation is required, the use of low tidal volumes (<6 ml/kg ideal body weight) and airway pressures (plateau pressure <30 cmH2O) was recommended. For patients with moderate/severe ARDS (partial pressure to fractional inspired oxygenratio <20), prone positioning was recommended for at least 16 hours per day. By contrast, high-frequency oscillation was not recommended. The use of inhaled vasodilators was recommended in patients with persistent hypoxemia despite invasive ventilation and prone position until extracorporeal membrane oxygenation (ECMO). The use of a conservative fluid management strategy was suggested for all patients. Mechanical ventilation with high positive end-expiratory pressure (PEEP) was suggestedfor patients with ARDS with a ratio of arterial oxygen partial pressure to fractional inspired oxygen (PF) ratios. ECMO was suggested as an adjunct to protective mechanical ventilation for patients with severe ARDS. In the absence of adequate evidence, research recommendations were made for corticosteroids and extracorporeal carbon dioxide removal. While decades of research have been conducted, treatment options for underlying pathologies remain limited, and mechanical ventilation, which removes carbon dioxide from the body, remains essential to achieving better clinical outcomes. This review aims to identify the best ARDStreatments that are currently available.

Brain-Lung Crosstalk: Management of Concomitant Severe Acute Brain Injury and Acute Respiratory Distress Syndrome.

Purpose of ReviewTo summarize pathophysiology, key conflicts, and therapeutic approaches in managing concomitant severe acute brain injury (SABI) and acute respiratory distress syndrome (ARDS).Recent FindingsARDS is common in SABI and independently associated with worse outcomes in all SABI subtypes. Most landmark ARDS trials excluded patients with SABI, and evidence to guide decisions is limited in this population. Potential areas of conflict in the management of patients with both SABI and ARDS are (1) risk of intracranial pressure (ICP) elevation with high levels of positive end-expiratory pressure (PEEP), permissive hypercapnia due to lung protective ventilation (LPV), or prone ventilation; (2) balancing a conservative fluid management strategy with ensuring adequate cerebral perfusion, particularly in patients with symptomatic vasospasm or impaired cerebrovascular blood flow; and (3) uncertainty about the benefit and harm of corticosteroids in this population, with a mortality benefit in ARDS, increased mortality shown in TBI, and conflicting data in other SABI subtypes. Also, the widely adapted partial pressure of oxygen (PaO2) target of > 55 mmHg for ARDS may exacerbate secondary brain injury, and recent guidelines recommend higher goals of 80–120 mmHg in SABI. Distinct pathophysiology and trajectories among different SABI subtypes need to be considered.SummaryThe management of SABI with ARDS is highly complex, and conventional ARDS management strategies may result in increased ICP and decreased cerebral perfusion. A crucial aspect of concurrent management is to recognize the risk of secondary brain injury in the individual patient, monitor with vigilance, and adjust management during critical time windows. The care of these patients requires meticulous attention to oxygenation and ventilation, hemodynamics, temperature management, and the neurological exam. LPV and prone ventilation should be utilized, and supplemented with invasive ICP monitoring if there is concern for cerebral edema and increased ICP. PEEP titration should be deliberate, involving measures of hemodynamic, pulmonary, and brain physiology. Serial volume status assessments should be performed in SABI and ARDS, and fluid management should be individualized based on measures of brain perfusion, the neurological exam, and cardiopulmonary status. More research is needed to define risks and benefits in corticosteroids in this population.

ARDS Patients Exhibiting a "Hyperinflammatory Anasarca" Phenotype Could Benefit From a Conservative Fluid Management Strategy.

Object: The fluid management strategy in ARDS is not very clear. A secondary analysis of RCT data was conducted to identify patients with ARDS benefitting from a conservative strategy of fluid management.Methods: The data of this study were downloaded from the ARDS network series of randomized controlled trials (Conservative Strategy vs. Liberal Strategy in 2006). Based on the clinical feature of patients, within the first 24 h after admission, clustering was performed using the k-means clustering algorithm to identify the phenotypes of ARDS. Survival was analyzed using the Kaplan-Meier survival analysis to assess the effect of the two fluid management strategies on the 90-day cumulative mortality. Categorical/dichotomic variables were analyzed by the chi-square test. Continuous variables were expressed as the mean and standard deviation and evaluated through a one-way ANOVA. A P-value < 0.05 was defined as the statistically significant cut-off value.Results: A total of 1,000 ARDS patients were enrolled in this unsupervised clustering research study, of which 503 patients were treated with a conservative fluid-management strategy, and 497 patients were treated with a liberal fluid-management strategy. The first 7-day cumulative fluid balance in patients with the conservative strategy and liberal strategy were −136 ± 491 ml and 6,992 ± 502 ml, respectively (P < 0.001). Four phenotypes were found, and the conservative fluid-management strategy significantly improved the 90-day cumulative mortality compared with the liberal fluid-management strategy (HR = 0.532, P = 0.024) in patients classified as “hyperinflammatory anasarca” phenotype (phenotype II). The characteristics of this phenotype exhibited a higher WBC count (20487.51 ± 7223.86/mm3) with a higher incidence of anasarca (8.3%) and incidence of shock (26.6%) at baseline. The furthermore analysis found that the conservative fluid management strategy was superior to the liberal fluid management strategy in avoiding superinfection (10.10 vs. 14.40%, P = 0.037) and returned to assisted breathing (4.60 vs. 16.20%, P = 0.030) in patients classified as “hyperinflammatory anasarca” phenotype. In addition, patients with other phenotypes given the different fluid management strategies did not show significant differences in clinical outcomes.Conclusion: Patients exhibiting a “hyperinflammatory anasarca” phenotype could benefit from a conservative fluid management strategy.

A Multicenter, Open-Label, Randomized Controlled Trial of a Conservative Fluid Management Strategy Compared With Usual Care in Participants After Cardiac Surgery: The Fluids After Bypass Study.

There is little evidence to guide fluid administration to patients admitted to the ICU following cardiac surgery. This study aimed to determine if a protocolized strategy known to reduce fluid administration when compared with usual care reduced ICU length of stay following cardiac surgery. Prospective, multicenter, parallel-group, randomized clinical trial. Five cardiac surgical centers in New Zealand conducted from November 2016 to December 2018 with final follow-up completed in July 2019. Seven-hundred fifteen patients undergoing cardiac surgery; 358 intervention and 357 usual care. Randomization to protocol-guided strategy utilizing stroke volume variation to guide administration of bolus fluid or usual care fluid administration until desedation or up to 24 hours. Primary outcome was length of stay in ICU. Organ dysfunction, mortality, process of care measures, patient-reported quality of life, and disability-free survival were collected up to day 180. Overall 666 of 715 (93.1%) received at least one fluid bolus. Patients in the intervention group received less bolus fluid (median [interquartile range], 1,000 mL [250-2,000 mL] vs 1,500 mL [500-2,500 mL]; p < 0.0001) and had a lower overall fluid balance (median [interquartile range], 319 mL [-284 to 1,274 mL] vs 673 mL [38-1,641 mL]; p < 0.0001) in the intervention period. There was no difference in ICU length of stay between the two groups (27.9 hr [21.8-53.5 hr] vs 25.6 hr [21.9-64.6 hr]; p = 0.95). There were no differences seen in development of organ dysfunction, quality of life, or disability-free survival at any time points. Hospital mortality was higher in the intervention group (4% vs 1.4%; p = 0.04). A protocol-guided strategy utilizing stroke volume variation to guide administration of bolus fluid when compared with usual care until desedation or up to 24 hours reduced the amount of fluid administered but did not reduce the length of stay in ICU.

Pragmatic Recommendations for the Prevention and Treatment of Acute Kidney Injury in Patients with COVID-19 in Low- and Middle-Income Countries.

.Current recommendations for the management of patients with COVID-19 and acute kidney injury (AKI) are largely based on evidence from resource-rich settings, mostly located in high-income countries. It is often unpractical to apply these recommendations to resource-restricted settings. We report on a set of pragmatic recommendations for the prevention, diagnosis, and management of patients with COVID-19 and AKI in low- and middle-income countries (LMICs). For the prevention of AKI among patients with COVID-19 in LMICs, we recommend using isotonic crystalloid solutions for expansion of intravascular volume, avoiding nephrotoxic medications, and using a conservative fluid management strategy in patients with respiratory failure. For the diagnosis of AKI, we suggest that any patient with COVID-19 presenting with an elevated serum creatinine level without available historical values be considered as having AKI. If serum creatinine testing is not available, we suggest that patients with proteinuria should be considered to have possible AKI. We suggest expansion of the use of point-of-care serum creatinine and salivary urea nitrogen testing in community health settings, as funding and availability allow. For the management of patients with AKI and COVID-19 in LMICS, we recommend judicious use of intravenous fluid resuscitation. For patients requiring dialysis who do not have acute respiratory distress syndrome (ARDS), we suggest using peritoneal dialysis (PD) as first choice, where available and feasible. For patients requiring dialysis who do have ARDS, we suggest using hemodialysis, where available and feasible, to optimize fluid removal. We suggest using locally produced PD solutions when commercially produced solutions are unavailable or unaffordable.

Fluid Management in Patients with Acute Respiratory Distress Syndrome and Diabetes Mellitus: A propensity score matched analysis of the fluid and catheter treatment trial.

Diabetes mellitus results in an attenuated inflammatory response, reduces pulmonary microvascular permeability, and may decrease the risk of developing acute respiratory distress syndrome (ARDS). Studies have shown that patients with ARDS are better managed by a conservative as compared to liberal fluid management strategy. However, it is not known if the same fluid management principles hold true for patients with comorbid diabetes mellitus and ARDS.As diabetes mellitus results in reduced pulmonary microvascular permeability and an attenuated inflammatory response, we hypothesize that in the setting of ARDS, diabetic patients will be able to tolerate a positive fluid balance better than patients without diabetes.The Fluid and Catheter Treatment Trial (FACTT) randomized patients with ARDS to conservative versus liberal fluid management strategies. In a secondary analysis of this trial, we calculated the interaction of diabetic status and differing fluid strategies on outcomes. Propensity score subclassification matching was used to control for the differing baseline characteristics between patients with and without diabetes.Nine hundred fifty-six patients were analyzed. In a propensity score matched analysis, the difference in the effect of a conservative as compared to liberal fluid management strategy on ventilator free days was 2.23 days (95% CI: -0.97 to 5.43 days) in diabetic patients, and 2.37 days (95% CI: -0.21 to 4.95 days) in non-diabetic patients. The difference in the effect of a conservative as compared to liberal fluid management on 60 day mortality was 2% (95% CI: -11.8% to 15.8%) in diabetic patients, and -7.9% (95% CI: -21.7% to 5.9%) in non-diabetic patients.When comparing a conservative fluid management strategy to a liberal fluid management strategy, diabetic patients with ARDS did not have a statistically significant difference in outcomes than non-diabetic patients.

Critically Ill Adults With Coronavirus Disease 2019 in New Orleans and Care With an Evidence-Based Protocol

BackgroundCharacteristics of critically ill adults with coronavirus disease 2019 (COVID-19) in an academic safety net hospital and the effect of evidence-based practices in these patients are unknown.Research QuestionWhat are the outcomes of critically ill adults with COVID-19 admitted to a network of hospitals in New Orleans, Louisiana, and what is an evidence-based protocol for care associated with improved outcomes?Study Design and MethodsIn this multi-center, retrospective, observational cohort study of ICUs in four hospitals in New Orleans, Louisiana, we collected data on adults admitted to an ICU and tested for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) between March 9, 2020 and April 14, 2020. The exposure of interest was admission to an ICU that implemented an evidence-based protocol for COVID-19 care. The primary outcome was ventilator-free days.ResultsThe initial 147 patients admitted to any ICU and tested positive for SARS-CoV-2 constituted the cohort for this study. In the entire network, exposure to an evidence-based protocol was associated with more ventilator-free days (25 days; 0-28) compared with non-protocolized ICUs (0 days; 0-23, P = .005), including in adjusted analyses (P = .02). Twenty patients (37%) admitted to protocolized ICUs died compared with 51 (56%; P = .02) in non-protocolized ICUs. Among 82 patients admitted to the academic safety net hospital’s ICUs, the median number of ventilator-free days was 22 (interquartile range, 0-27) and mortality rate was 39%.InterpretationCare of critically ill COVID-19 patients with an evidence-based protocol is associated with increased time alive and free of invasive mechanical ventilation. In-hospital survival occurred in most critically ill adults with COVID-19 admitted to an academic safety net hospital’s ICUs despite a high rate of comorbidities.

Guidelines on the management of acute respiratory distress syndrome

The Faculty of Intensive Care Medicine and Intensive Care Society Guideline Development Group have used GRADE methodology to make the following recommendations for the management of adult patients with acute...

Design and statistical analysis plan for a trial comparing a conservative fluid management strategy with usual care in patients after cardiac surgery: the FAB study

Design and statistical analysis plan for a trial comparing a conservative fluid management strategy with usual care in patients after cardiac surgery: the FAB study

Mechanical ventilation in acute hypoxemic respiratory failure: a review of new strategies for the practicing hospitalist.

The goal of mechanical ventilation in acute hypoxemic respiratory failure is to support adequate gas exchange without harming the lungs. How patients are mechanically ventilated can significantly impact their ultimate outcomes. This review focuses on emerging evidence regarding strategies for mechanical ventilation in patients with acute hypoxemic respiratory failure including: low tidal volume ventilation in the acute respiratory distress syndrome (ARDS), novel ventilator modes as alternatives to low tidal volume ventilation, adjunctive strategies that may enhance recovery in ARDS, the use of lung-protective strategies in patients without ARDS, rescue therapies in refractory hypoxemia, and an evidence-based approach to weaning from mechanical ventilation. Once a patient is intubated and mechanically ventilated, low tidal volume ventilation remains the best strategy in ARDS. Adjunctive therapies in ARDS include a conservative fluid management strategy, as well as neuromuscular blockade and prone positioning in moderate-to-severe disease. There is also emerging evidence that a lung-protective strategy may benefit non-ARDS patients. For patients with refractory hypoxemia, extracorporeal membrane oxygenation should be considered. Once the patient demonstrates signs of recovery, the best approach to liberation from mechanical ventilation involves daily spontaneous breathing trials and protocolized assessment of readiness for extubation. Prompt recognition of ARDS and use of lung-protective ventilation, as well as evidence-based adjunctive therapies, remain the cornerstones of caring for patients with acute hypoxemic respiratory failure. In the absence of contraindications, it is reasonable to consider lung-protective ventilation in non-ARDS patients as well, though the evidence supporting this practice is less conclusive.

Extracorporeal membrane oxygenation for refractory acute respiratory distress syndrome in severe malaria

BackgroundSevere malaria may be complicated by the acute respiratory distress syndrome (ARDS), which is associated with a high mortality. In the present report, a series of three cases of imported malaria complicated by refractory severe ARDS supported with extracorporeal membrane oxygenation (ECMO) is presented.MethodsOne female and two male adult patients (ages 39 to 53) were included. Two patients had Plasmodium falciparum infection and one patient had Plasmodium vivax and Plasmodium ovale co-infection. Anti-malarial therapy consisted in intravenous quinine (in two patients) and intravenous quinidine (in one patient), plus clindamycin or doxycycline.ResultsDespite lung protective ventilation, a conservative strategy of fluid management, corticosteroids (two patients), prone position (two patients) and inhaled nitric oxide (one patient), refractory severe ARDS supervened (PaO2 to FiO2 ratio 68) and venovenous ECMO was then initiated. In one patient, a bicaval dual-lumen cannula was inserted; in the two other patients, a two-site configuration was used. Two patients survived to hospital-discharge (duration of ECMO support: 8.5 days) and one patient died from nosocomial sepsis and multi-organ failure after 40 days of ECMO support.ConclusionsECMO support allowed adequate oxygenation and correction of hypercapnia under lung protective ventilation, therefore reducing ventilator-induced lung injury. ECMO referral should be considered early in malaria complicated by severe ARDS refractory to conventional treatment.

Echocardiography to predict tolerance to negative fluid balance in acute respiratory distress syndrome/acute lung injury

PurposeIn acute respiratory distress syndrome (ARDS) and acute lung injury (ALI), a conservative fluid management strategy improves lung function but could jeopardize extrapulmonary organ perfusion. The objective was to evaluate the diagnostic accuracy of echocardiography to predict tolerance of negative fluid balance (NFB) in patients with ARDS/ALI. Materials and MethodsA prospective and observational study in an adult intensive care unit of a university hospital was conducted. All hemodynamically stable patients with ARDS/ALI were included. Echocardiography was performed before NFB and again after 24 hours. Tolerance of NFB was evaluated by the presence of hypotension, acute kidney injury, or need for fluid expansion. The 2 patient groups (tolerating and not tolerating NFB) were compared. ResultsForty-five patients were included. Median age (Q1-Q3) was 58 (52-66) years, and the ratio of partial pressure of arterial oxygen to the fraction of inspired oxygen was 205 (163-258) mm Hg. Negative fluid balance was 1950 (1200-2200) mL within 24 hours in the tolerant group. Complications of NFB were observed in 35% cases. After univariate and multivariate logistic regression analyzes, 2 criteria was independently associates with poor tolerance: mitral inflow E wave to early diastolic mitral annulus velocities ratio (E/Ea ratio; odds ratio, 2.02 [1.02-4.02]; P = .04) and weight gain (odds ratio, 1.2 [1.03-1.4]; P = .02). The area under receiver operating characteristic curves was 0.74 for E/Ea and 0.77 for weight gain. ConclusionsThe ratio of E/Ea accurately predicted tolerance of NFB in patients with ARDS/ALI.

The Adult Respiratory Distress Syndrome Cognitive Outcomes Study: long-term neuropsychological function in survivors of acute lung injury

Expanded abstractCitationMikkelsen ME, Christie JD, Lanken PN, Biester RC, Thompson BT, Bellamy SL, Localio AR, Demissie E, Hopkins RO, Angus DC: The adult respiratory distress syndrome cognitive outcomes study: long-term neuropsychological function in survivors of acute lung injury. Am J Respir Crit Care Med 2012, 185:1307-1315.BackgroundCognitive and psychiatric morbidity is common and potentially modifiable after acute lung injury (ALI). However, practical measures of neuropsychological function for use in multicenter trials are lacking.MethodsObjectiveThe objectives were to determine whether a validated telephone-based neuropsychological test battery is feasible in a multicenter trial and to determine the frequency and risk factors for long-term neuropsychological impairment.DesignA prospective, multicenter cohort study of a subset of survivors from the Fluid and Catheter Treatment Trial (FACTT) was conducted.SettingThe FACTT enrolled patients from 38 North American hospitals between June 2000 and October 2005.SubjectsTo be eligible for the ALI Cognitive Outcomes Study (ACOS), subjects had to be enrolled in the FACTT and the EA-PAC (Economic Assessment of the Pulmonary Artery Catheter) trial. The FACTT enrolled mechanically ventilated adults who met the American-European Consensus Conference criteria for ALI.InterventionIn an adjunct study to the Acute Respiratory Distress Syndrome Clinical Trials Network Fluid and Catheter Treatment Trial, neuropsychological function at 2 and 12 months after hospital discharge was assessed.OutcomesThe primary outcome was the result of a validated telephone battery of standardized neuropsychological tests administered to consenting, English-speaking subjects at 2 and 12 months after hospital discharge.ResultsOf 406 eligible survivors, 261 patients were approached to participate and 213 consented. One hundred twenty-two subjects, including 102 subjects at 12 months, were tested at least once. Memory, verbal fluency, and executive function were impaired in 13% (12 of 92), 16% (15 of 96), and 49% (37 of 76) of long-term survivors, respectively. Long-term cognitive impairment was present in 41 (55%) of the 75 survivors who completed cognitive testing. Depression, post-traumatic stress disorder, and anxiety were present in 36% (37 of 102), 39% (40 of 102), and 62% (63 of 102) of long-term survivors, respectively. Enrollment in a conservative fluid management strategy (P <0.005) was associated with cognitive impairment, and lower partial pressure of arterial oxygen during the trial was associated with cognitive (P <0.02) and psychiatric (P <0.02) impairment.ConclusionsNeuropsychological function can be assessed by telephone in a multicenter trial. Long-term neuropsychological impairment is common in survivors of ALI. Hypoxemia is a risk factor for long-term neuropsychological impairment. A fluid management strategy is a potential risk factor for long-term cognitive impairment; however, given the select population studied and an unclear mechanism, this finding requires confirmation.

Fluid balance in critically ill children with acute lung injury*

In the Fluid and Catheter Treatment Trial (NCT00281268), adults with acute lung injury randomized to a conservative vs. liberal fluid management protocol had increased days alive and free of mechanical ventilator support (ventilator-free days). Recruiting sufficient children with acute lung injury into a pediatric trial is challenging. A Bayesian statistical approach relies on the adult trial for the a priori effect estimate, requiring fewer patients. Preparing for a Bayesian pediatric trial mirroring the Fluid and Catheter Treatment Trial, we aimed to: 1) identify an inverse association between fluid balance and ventilator-free days; and 2) determine if fluid balance over time is more similar to adults in the Fluid and Catheter Treatment Trial liberal or conservative arms. Multicentered retrospective cohort study. Five pediatric intensive care units. Mechanically ventilated children (age≥1 month to <18 yrs) with acute lung injury admitted in 2007-2010. None. Fluid intake, output, and net fluid balance were collected on days 1-7 in 168 children with acute lung injury (median age 3 yrs, median PaO2/FIO2 138) and weight-adjusted (mL/kg). Using multivariable linear regression to adjust for age, gender, race, admission day illness severity, PaO2/FIO2, and vasopressor use, increasing cumulative fluid balance (mL/kg) on day 3 was associated with fewer ventilator-free days (p=.02). Adjusted for weight, daily fluid balance on days 1-3 and cumulative fluid balance on days 1-7 were higher in these children compared to adults in the Fluid and Catheter Treatment Trial conservative arm (p<.001, each day) and was similar to adults in the liberal arm. Increasing fluid balance on day 3 in children with acute lung injury at these centers is independently associated with fewer ventilator-free days. Our findings and the similarity of fluid balance patterns in our cohort to adults in the Fluid and Catheter Treatment Trial liberal arm demonstrate the need to determine whether a conservative fluid management strategy improves clinical outcomes in children with acute lung injury and support a Bayesian trial mirroring the Fluid and Catheter Treatment Trial.

Does a conservative fluid management strategy in the perioperative management of lung resection patients reduce the risk of acute lung injury?

A best evidence topic in thoracic surgery was written according to a structured protocol. The question addressed was whether a conservative fluid management strategy in the perioperative management of lung resection patients is associated with a reduced incidence of postoperative acute lung injury (PALI) and/or acute respiratory distress syndrome (ARDS) in the recovery period. Sixty-seven papers were found using the reported search, of which 13 level III and 1 level IV evidence studies represented the best evidence to answer the question. Two retrospective case-control studies demonstrated a direct association between liberal fluid intake and the incidence of PALI/ARDS following lung resection on multivariate analysis (MVA) with odds ratios (ORs) of 1.42 (95% CI 1.09-4.32, P = 0.011) and 2.91 (1.9-7.4, P = 0.001). In non-PALI/ARDS cases, the mean intraoperative fluid infusion volume was significantly less [1.22 l (1.17-1.26) vs 1.68 l (1.46-1.9) P = 0.005], the fluid balance over the first 24 postoperative hours was significantly less [1.52 l positive (1.44-1.60) vs 2.0 l positive (1.6-2.4) P = 0.026] and cumulated intra- and postoperative fluid infusion was significantly less [2.0 ml/kg/h (1.7-2.3) vs 2.6 ml/kg/h (2.3-2.9) P = 0.003]. These data show that the difference between fluid regimes associated with an increased incidence of PALI/ARDS (i.e. 'liberal') and those which are not (i.e. 'conservative') is narrow but significant. However, this does not prove a causative role for liberal fluid in the multifactorial development of PALI/ARDS. On this best evidence, we recommend intra- and postoperative maintenance fluid to be administered at 1-2 ml/kg/h and that a positive fluid balance of 1.5 l should not be exceeded in the perioperative period with caution being exercised with regard to the adequacy of oxygen delivery. If the fluid balance exceeds this threshold, a high index of suspicion for PALI/ARDS should be adopted and escalation of the level of care should be considered. If a patient develops signs of hypoperfusion after these thresholds are exceeded, inotropic/vasopressor support should be considered.

Effect of conservative fluid management strategy on the outcomes in patients with acute lung injury: a meta-analysis

To evaluate the effect of conservative fluid management on the outcomes in patients with acute lung injury (ALI). Randomized controlled trials (RCTs) and cohort trials on conservative fluid management from January 1, 1990 to May 20, 2010 were retrieved by electronic and manual searching. A meta-analysis of effect of conservative fluid management on the outcomes in ALI patients was conducted by the methods as recommended by the Cochrane Collaboration. Four RCTs involving 594 cases in conservative fluid management group and 584 in conventional fluid management group were included into the Meta-analysis. Compared with the conventional fluid management group, there was no beneficial effect of conservative fluid management strategy on mortality in ALI patients (P = 0.16). However, the duration of mechanical ventilation was shortened while the incidence of renal failure remained unchanged. Three retrospective cohort trials involving 296 cases in conservative fluid management group and 750 in conventional fluid management group were included into the meta-analysis. As compared with the conventional fluid management strategy, conservative fluid management strategy had improved the patient outcomes (P < 0.001). No beneficial effect of conservative fluid management strategy on the mortality is observed in the ALI patients. And the ventilator-free durations become elongated. However, further trials of a larger sample size and a higher quality are warranted.

Fluid balance and acute kidney injury

Intravenous fluids are widely administered to patients who have, or are at risk of, acute kidney injury (AKI). However, deleterious consequences of overzealous fluid therapy are increasingly being recognized. Salt and water overload can predispose to organ dysfunction, impaired wound healing and nosocomial infection, particularly in patients with AKI, in whom fluid challenges are frequent and excretion is impaired. In this Review article, we discuss how interstitial edema can further delay renal recovery and why conservative fluid strategies are now being advocated. Applying these strategies in critical illness is challenging. Although volume resuscitation is needed to restore cardiac output, it often leads to tissue edema, thereby contributing to ongoing organ dysfunction. Conservative strategies of fluid management mandate a switch towards neutral balance and then negative balance once hemodynamic stabilization is achieved. In patients with AKI, this strategy might require renal replacement therapy to be given earlier than when more-liberal fluid management is used. However, hypovolemia and renal hypoperfusion can occur in patients with AKI if excessive fluid removal is pursued with diuretics or extracorporeal therapy. Thus, accurate assessment of fluid status and careful definition of targets are needed at all stages to improve clinical outcomes. A conservative strategy of fluid management was recently tested and found to be effective in a large, randomized, controlled trial in patients with acute lung injury. Similar randomized, controlled studies in patients with AKI now seem justified.

Advances in critical care for the nephrologist: acute lung injury/ARDS.

Acute lung injury (ALI) and the acute respiratory distress syndrome (ARDS) are a major cause of acute respiratory failure in the critically ill patient. ALI and ARDS are characterized by the acute onset of severe hypoxemia and bilateral pulmonary infiltrates in the absence of clinical evidence for left atrial hypertension. These conditions are differentiated from one another by the ratio of the partial pressure of oxygen in the arterial blood to the inspired fraction of oxygen; ARDS requires a more severe oxygenation defect. ALI and ARDS may occur in association with a number of clinical disorders, including sepsis, pneumonia, aspiration, trauma including inhalational injury, and blood transfusions. The mortality rate remains high, in the range of 25% to 40%. The pathophysiology of ALI/ARDS involves resident lung cells, including endothelial and epithelial cells, as well as neutrophils, monocytes/macrophages, and platelets. When ALI/ARDS is complicated by acute kidney injury, mortality increases substantially. Several supportive and pharmacologic therapies have been tested in clinical trials. Of these, a low tidal volume, lung protective ventilation strategy is the only strategy that has been demonstrated in a large, multicenter randomized clinical trial to reduce mortality for patients with ALI/ARDS. Based on a recent randomized trial, a conservative fluid management strategy reduces the duration of mechanical ventilation without increasing the incidence of renal failure. Pharmacologic strategies and other ventilator management strategies have not been successful to date; however, several randomized, placebo controlled treatment trials are ongoing.

Nonventilatory Treatments for Acute Lung Injury and ARDS

Over the past decade, advances in the ventilatory management of acute lung injury (ALI) and ARDS have improved outcomes; however, until recently the search for other therapies has been less fruitful. Recently, the Acute Respiratory Distress Syndrome Network Fluid and Catheter Treatment Trial reported that a conservative fluid management strategy, compared with a fluid liberal strategy, increased the mean (± SE) number of ventilator-free days in patients with ALI (14.6 ± 0.5 vs 12.1 ± 0.5 days, respectively; p < 0.001). In addition to this beneficial effect on outcomes, the study found that the conservative fluid strategy did not increase the incidence of renal failure or the development of shock. Other studies have demonstrated that albumin and furosemide therapy may be beneficial in hypoproteinemic patients with lung injury, though data on outcomes is still lacking. Although several pharmacologic therapies, such as corticosteroids, surfactant, and nitric oxide, have been demonstrated to be ineffective in improving outcomes, several promising new treatments are being investigated in ongoing or upcoming clinical trials. This article reviews these developments and other recent research on the optimal nonventilatory management of patients with ALI.

A conservative fluid management strategy did not affect risk for death but shortened duration of ventilation in acute lung injury

Source Citation Wiedemann HP, Wheeler AP, Bernard GR, et al. Comparison of two fluid-management strategies in acute lung injury. N Engl J Med. 2006;354:2564-75. 16714767