Acute respiratory distress syndrome. Potential pharmacologic interventions

Acute Respiratory Distress Syndrome in Cancer Patients

Acute respiratory distress syndrome (ARDS) is a heterogeneous form of acute, diffuse lung injury that is characterized by dysregulated inflammation, increased alveolar-capillary interface permeability, and non-cardiogenic pulmonary edema. In the general population, the incidence and mortality associated with ARDS over the last two decades have steadily declined in parallel with optimized approaches to pneumonia and other underlying causes of ARDS as well as increased utilization of multimodal treatment strategies that include lung-protective ventilation. In the cancer settings, significant declines in the incidence and mortality of ARDS over the past two decades have also been reported, although these rates remain significantly higher than those in the general population. Epidemiologic studies identify infection, including disseminated fungal pneumonias, as a major underlying cause of ARDS in the cancer setting. More than half of cancer patients who develop ARDS will not survive to hospital discharge. Those who do survive often face a protracted and often incomplete recovery, resulting in significant long-term physical, psychological, and cognitive sequelae. The residual organ dysfunction and poor functional status after ARDS may delay or preclude subsequent cancer treatments. As such, close collaboration between the critical care physicians and oncology team is essential in identifying and reversing the underlying causes and optimizing treatments for cancer patients with ARDS. This chapter reviews the diagnosis and common causes of ARDS in cancer and gives an update on the general management principles for cancer patients with ARDS in the ICU.

Reactive oxygen species in pulmonary vascular remodeling

The pathogenesis of pulmonary hypertension is a complex multifactorial process that involves the remodeling of pulmonary arteries. This remodeling process encompasses concentric medial thickening of small arterioles, neomuscularization of previously nonmuscular capillary-like vessels, and structural wall changes in larger pulmonary arteries. The pulmonary arterial muscularization is characterized by vascular smooth muscle cell hyperplasia and hypertrophy. In addition, in uncontrolled pulmonary hypertension, the clonal expansion of apoptosis-resistant endothelial cells leads to the formation of plexiform lesions. Based upon a large number of studies in animal models, the three major stimuli that drive the vascular remodeling process are inflammation, shear stress, and hypoxia. Although, the precise mechanisms by which these stimuli impair pulmonary vascular function and structure are unknown, reactive oxygen species (ROS)-mediated oxidative damage appears to play an important role. ROS are highly reactive due to their unpaired valence shell electron. Oxidative damage occurs when the production of ROS exceeds the quenching capacity of the antioxidant mechanisms of the cell. ROS can be produced from complexes in the cell membrane (nicotinamide adenine dinucleotide phosphate-oxidase), cellular organelles (peroxisomes and mitochondria), and in the cytoplasm (xanthine oxidase). Furthermore, low levels of tetrahydrobiopterin (BH4) and L-arginine the rate limiting cofactor and substrate for endothelial nitric oxide synthase (eNOS), can cause the uncoupling of eNOS, resulting in decreased NO production and increased ROS production. This review will focus on the ROS generation systems, scavenger antioxidants, and oxidative stress associated alterations in vascular remodeling in pulmonary hypertension.

Partial liquid ventilation for preventing death and morbidity in adults with acute lung injury and acute respiratory distress syndrome

BACKGROUND

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are syndromes of severe respiratory failure that are associated with substantial mortality and morbidity. Artifical ventilatory support is commonly required and may exacerbate lung injury. Partial liquid ventilation (PLV) has been proposed as a less injurious form of ventilatory support for these patients. Although PLV has been shown to improve gas exchange and to reduce inflammation in experimental models of ALI, a previous systematic review did not find any evidence to support or refute its use in humans with ALI and ARDS.

OBJECTIVES

The primary objective of this review was to assess whether PLV reduced mortality (at 28 d, at discharge from the intensive care unit (ICU), at discharge from hospital and at one, two and five years) in adults with ALI or ARDS when compared with conventional ventilatory support.Secondary objectives were to determine how PLV compared with conventional ventilation with regard to duration of invasive mechanical ventilation, duration of respiratory support, duration of oxygen therapy, length of ICU stay, length of hospital stay, incidence of infection, long-term cognitive impairment, long-term health related quality of life, long- term lung function, long-term morbidity costs and adverse events. The following adverse events were considered: hypoxia (arterial PO2 <80 mm Hg), pneumothorax (any air leak into the pleural space requiring therapeutic intervention), hypotension (systolic blood pressure < 90 mm Hg sustained for longer than two minutes or requiring treatment with fluids or vasoactive drugs), bradycardia (heart rate < 50 beats per minute sustained for longer than one minute or requiring therapeutic intervention) and cardiac arrest (absence of effective cardiac output).

SEARCH METHODS

In this updated review, we searched the Cochrane Central Register of Controlled Trials (CENTRAL Issue 10, 2012, in The Cochrane Library; MEDLINE (Ovid SP, 1966 to November 2012); EMBASE (Ovid SP, 1980 to November 2012) and CINAHL (EBSCOhost,1982 to November 2012) for published studies. In our original review, we searched until May 2004.Grey literature was identified by searching conference proceedings and trial registries and by contacting experts in the field.

SELECTION CRITERIA

As in the original review, review authors selected randomized controlled trials that compared PLV with other forms of ventilation in adults (16 y of age or older) with ALI or ARDS, reporting one or more of the following: mortality; duration of mechanical ventilation, respiratory support, oxygen therapy, stay in the intensive care unit or stay in hospital; infection; long-term cognitive impairment or health-related quality of life; long-term lung function or cost.

DATA COLLECTION AND ANALYSIS

Two review authors independently evaluated the quality of the relevant studies and extracted the data from included studies.

MAIN RESULTS

In this updated review, one new eligible study was identified and included, yielding a total of two eligible studies (including a combined total of 401 participants). Of those 401 participants, 170 received 'high'-dose partial liquid ventilation (i.e. a mean dose of at least 20 mL/kg), 99 received 'low-dose' partial liquid ventilation (i.e. a dose of 10 mL/kg) and 132 received conventional mechanical ventilation (CMV). Pooled estimates of effect were calculated for all those who received 'high'-dose PLV versus conventional ventilation. No evidence indicated that 'high'-dose PLV either reduced mortality at 28 d (risk ratio (RR) 1.21, 95% confidence interval (CI) 0.79 to 1.85, P = 0.37) or increased the number of days free of CMV at 28 d (mean difference (MD) -2.24, 95% CI -4.71 to 0.23, P = 0.08). The pooled estimate of effect for bradycardia in those who received PLV was significantly greater than in those who received CMV (RR 2.51, 95% CI 1.31 to 4.81, P = 0.005). Pooled estimates of effect for the following adverse events- hypoxia, pneumothorax, hypotension and cardiac arrest- all showed a nonsignificant trend towards a higher occurrence of these events in those treated with PLV. Because neither eligible study addressed morbidity or mortality beyond 28 d, it was not possible to determine the effect of PLV on these outcomes.

AUTHORS' CONCLUSIONS

No evidence supports the use of PLV in ALI or ARDS; some evidence suggests an increased risk of adverse events associated with its use.

Partial liquid ventilation for the prevention of mortality and morbidity in paediatric acute lung injury and acute respiratory distress syndrome

BACKGROUND

Acute lung injury and acute respiratory distress syndrome are syndromes of severe respiratory failure. Children with acute lung injury or acute respiratory distress syndrome have high mortality and the survivors have significant morbidity. Partial liquid ventilation is proposed as a less injurious form of respiratory support for these children. Uncontrolled studies in adults have shown improvements in gas exchange and lung compliance with partial liquid ventilation. A single uncontrolled study in six children with acute respiratory syndrome showed some improvement in gas exchange during three hours of partial liquid ventilation. This review was originally published in 2004, updated in 2009 and again in 2012.

OBJECTIVES

To assess whether partial liquid ventilation reduces mortality or morbidity, or both, in children with acute lung injury or acute respiratory distress syndrome.

SEARCH METHODS

In this updated review, we searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2011, Issue 11); CINAHL (Cumulative Index to Nursing & Allied Health Literature) via Ovid (1982 to November 2011); Ovid MEDLINE (1950 to November 2011); and Ovid EMBASE (1982 to November 2011). The search was last performed in August 2008.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) which compared partial liquid ventilation with other forms of ventilation in children (aged 28 days to 18 years) with acute lung injury or acute respiratory distress syndrome. Trials had to report one or more of the following: mortality; duration of mechanical ventilation, respiratory support, oxygen therapy, stay in the intensive care unit, or stay in hospital; infection; long-term cognitive impairment, neurodevelopmental progress, or other long-term morbidities.

DATA COLLECTION AND ANALYSIS

We independently evaluated the quality of the relevant studies and extracted the data from the included studies.

MAIN RESULTS

Only one study enrolling 182 patients (reported as an abstract in conference proceedings) was identified and found eligible for inclusion; the authors reported only limited results. The trial was stopped prematurely and was, therefore, under-powered to detect any significant differences and at high risk of bias. The only available outcome of clinical significance was 28-day mortality. There was no statistically significant difference between groups, with a relative risk for 28-day mortality in the partial liquid ventilation group of 1.54 (95% confidence interval 0.82 to 2.9).

AUTHORS' CONCLUSIONS

There is no evidence from RCTs to support or refute the use of partial liquid ventilation in children with acute lung injury or acute respiratory distress syndrome. Adequately powered, high quality RCTs are still needed to assess its efficacy. Clinically relevant outcome measures should be assessed (mortality at discharge and later, duration of both respiratory support and hospital stay, and long-term neurodevelopmental outcomes). The studies should be published in full.

Effect of nitric oxide on oxygenation and mortality in acute lung injury: systematic review and meta-analysis

OBJECTIVE

To review the literature on the use of inhaled nitric oxide to treat acute lung injury/acute respiratory distress syndrome (ALI/ARDS) and to summarise the effects of nitric oxide, compared with placebo or usual care without nitric oxide, in adults and children with ALI or ARDS.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Medline, CINAHL, Embase, and CENTRAL (to October 2006), proceedings from four conferences, and additional information from authors of 10 trials.

REVIEW METHODS

Two reviewers independently selected parallel group randomised controlled trials comparing nitric oxide with control and extracted data related to study methods, clinical and physiological outcomes, and adverse events.

MAIN OUTCOME MEASURES

Mortality, duration of ventilation, oxygenation, pulmonary arterial pressure, adverse events.

RESULTS

12 trials randomly assigning 1237 patients met inclusion criteria. Overall methodological quality was good. Using random effects models, we found no significant effect of nitric oxide on hospital mortality (risk ratio 1.10, 95% confidence interval 0.94 to 1.30), duration of ventilation, or ventilator-free days. On day one of treatment, nitric oxide increased the ratio of partial pressure of oxygen to fraction of inspired oxygen (PaO2/FiO2 ratio) (13%, 4% to 23%) and decreased the oxygenation index (14%, 2% to 25%). Some evidence suggested that improvements in oxygenation persisted until day four. There was no effect on mean pulmonary arterial pressure. Patients receiving nitric oxide had an increased risk of developing renal dysfunction (1.50, 1.11 to 2.02).

CONCLUSIONS

Nitric oxide is associated with limited improvement in oxygenation in patients with ALI or ARDS but confers no mortality benefit and may cause harm. We do not recommend its routine use in these severely ill patients.

Massive alveolar thrombin activation in Pseudomonas aeruginosa-induced acute lung injury

In acute lung injury (ALI), a coagulation/fibrinolysis imbalance leads to fibrin deposition, persistence of which contributes to fibrotic evolution. Our study evaluated the effects of early inhibition of coagulation in Pseudomonas aeruginosa (Pa)-induced ALI through the use of recombinant human antithrombin (rhAT). The study was conducted in vivo on a murine model of Pa-induced ALI. Intravenous rhAT was administered simultaneously with intratracheal Pa. Four experimental groups were compared: CTR, intratracheal saline (0.5 mL/kg)/intravenous saline (1 mL); PNP, intratracheal Pa (0.5 mL/kg of 2 x 10(9) cfu)/intravenous saline; AT, intratracheal saline/intravenous rhAT (500 IU/kg); ATPNP, intratracheal Pa/intravenous rhAT. Epithelial and endothelial permeabilities were evaluated with radiolabeled albumin flux across the alveolar barrier (125I- and 131I-labeled albumin). Thrombin-antithrombin (TAT) complexes levels were used as markers of coagulation activation in blood samples and in BAL fluid. Epithelial and endothelial protein permeability were increased in Pa-induced ALI versus control. Intravenous rhAT administration led to further permeability disorders. Administration of rhAT in Pa ALI led to a rise in TAT complexes in ATPNP blood serum and BAL fluids compared with the other groups. In Pa-induced ALI the administration intravenous rhAT leads to major histologic damage, alveolar capillary barrier injury, and permeability increase. Such effects of the inhibition of thrombin activation by rhAT lead to the hypothesis of a probable beneficial role of early coagulation activation in ALI as a factor limiting both the extent of injury and permeability disorders. Our study suggests that inhibition of this initial procoagulative imbalance is potentially dangerous.

Partial liquid ventilation for preventing death and morbidity in adults with acute lung injury and acute respiratory distress syndrome

BACKGROUND

Acute lung injury (ALI), and acute respiratory distress syndrome (ARDS), are syndromes of severe respiratory failure. Adults with ALI or ARDS have high mortality and significant morbidity. Partial liquid ventilation (PLV) may be better (i.e., cause less lung damage) for these patients than other forms of respiratory support. Uncontrolled studies in adults have shown improvement in gas exchange and lung compliance with partial liquid ventilation.

OBJECTIVES

To assess whether partial liquid ventilation reduces morbidity and mortality in adults with ALI or ARDS.

SEARCH STRATEGY

We searched The Cochrane Central Register of Controlled Trials (CENTRAL), The Cochrane Library Issue 2, 2004; MEDLINE (1966 to May 2004); and CINAHL (1982 to May 2004); intensive care journals and conference proceedings; reference lists and unpublished literature.

SELECTION CRITERIA

Randomized controlled trials which compared partial liquid ventilation with other forms of ventilation, in adults (16 years old or greater) with ALI or ARDS, reporting one or more of the following: mortality; duration of mechanical ventilation, respiratory support, oxygen therapy, stay in the intensive care unit, or stay in hospital; infection; long term cognitive impairment or health related quality of life; long term lung function; or cost.

DATA COLLECTION AND ANALYSIS

Two reviewers independently evaluated the quality of the relevant studies and extracted the data from the included studies.

MAIN RESULTS

Problems with the inadequacy of the primary report of the one included study do not allow us to report any quantitative results for patients with ALI or ARDS. The only outcome we considered to be of clinical significance and reported for all enrolled patients (i.e., patients with ALI and ARDS and less severe respiratory insufficiency) was 28 day mortality. There was no statistically significant difference between groups for this outcome with a relative risk for 28 day mortality in the PLV group of 1.15 (95% confidence intervals of 0.64 to 2.10).

REVIEWERS' CONCLUSIONS

There is no evidence from randomized controlled trials to support or refute the use of partial liquid ventilation in adults with ALI or ARDS; adequately powered, high quality randomized controlled trials are still needed to assess its efficacy. Clinically relevant outcome measures should be assessed (especially mortality at discharge and later, duration of respiratory support and hospital stay, and long term cognitive and quality of life outcomes) and the studies should be published in full.

Pharmacologic therapies for adults with acute lung injury and acute respiratory distress syndrome

BACKGROUND

Multiple pharmacologic treatments have been studied for acute lung injury (ALI) and acute respiratory distress syndrome (ARDS).

OBJECTIVES

Our objective was to determine the effects of pharmacologic treatments on clinical outcomes in adults with ALI or ARDS.

SEARCH STRATEGY

We searched OVID versions of CENTRAL (The Cochrane Library Issue 3, 2003), MEDLINE (1966 to week 2, January 2004), EMBASE (1980 to week 4, 2004), CINAHL (1982 to week 2, January 2004), and HEALTHSTAR (1995 to December 2003); proceedings from four conferences (1994 to 2003); and bibliographies of review articles and included studies.

SELECTION CRITERIA

Randomized controlled trials of pharmacologic treatments compared to no therapy or placebo for established ALI or ARDS in adults admitted to an intensive care unit, with measurement of early mortality (primary outcome), late mortality, duration of mechanical ventilation, ventilator-free days to day 28, or adverse events. We excluded trials of nitric oxide, partial liquid ventilation, fluid and nutritional interventions, oxygen, and trials in other populations reporting outcomes in subgroups of patients with ALI or ARDS.

DATA COLLECTION AND ANALYSIS

Two reviewers independently screened titles and abstracts, rated studies for inclusion, extracted data and assessed methodologic quality of included studies. Disagreements were resolved by consensus in consultation with a third reviewer. For each pharmacologic therapy, we quantitatively pooled the results of studies using random effects models where permitted by the available data. We contacted study authors when clarification of the primary outcome was required.

MAIN RESULTS

Thirty three trials randomizing 3272 patients met our inclusion criteria. Pooling of results showed no effect on early mortality of prostaglandin E1 (seven trials randomizing 697 patients; relative risk [RR] 0.95, 95% confidence interval [CI] 0.77 to 1.17), N-acetylcysteine (five trials randomizing 239 patients; RR 0.89, 95% CI 0.65 to 1.21), early high-dose corticosteroids (two trials randomizing 187 patients; RR 1.12, 95% CI 0.72 to 1.74), or surfactant (nine trials randomizing 1441 patients; RR 0.93, 95% CI 0.77 to 1.12). Two interventions were beneficial in single small trials; corticosteroids given for late phase ARDS reduced hospital mortality (24 patients; RR 0.20, 95% CI 0.05 to 0.81), and pentoxifylline reduced one-month mortality (RR 0.67, 95% CI 0.47 to 0.95) in 30 patients with metastatic cancer and ARDS. Individual trials of nine additional interventions failed to show a beneficial effect on prespecified outcomes.

REVIEWERS' CONCLUSIONS

Effective pharmacotherapy for ALI and ARDS is extremely limited, with insufficient evidence to support any specific intervention.

Acute lung injury using oleic acid in the laboratory rat: establishment of a working model and evidence against free radicals in the acute phase

OBJECTIVE

To determine the optimal model of acute respiratory distress syndrome (ARDS) using oleic acid in our laboratory and to measure the presence or absence of free radicals in this model.

DESIGN

This protocol consisted of 2 phases. During the first phase, various conditions were tested, to include different doses (30 or 50 microliters) of oleic acid, different levels of support (with and without mechanical ventilation), and different injury time periods (sacrifice 4 or 8 hours after injection). During the second phase, animals were randomly assigned to experimental (injured) and control (noninjured) groups for the measurement of free radicals by nitrotyrosine Western blot and by the conversion of hydroethidine to ethidium bromide by superoxide.

SETTING

Multidisciplinary laboratory and animal surgery suite.

PARTICIPANTS

Twenty-seven male Sprague-Dawley rats.

RESULTS

During the first phase, several animal deaths occurred in the high-dose, ventilated groups, whereas there were no deaths in the nonventilated animals. On hematoxylin and eosin stain, injury was greatest in the animals that received the higher dose of oleic acid and that were sacrificed at 8 hours. In the protocol's second phase, oxygen radical assays were negative for all experimental and control lungs.

CONCLUSIONS

During this study, we successfully established a working animal model of ARDS for our laboratory. Our findings to date suggest that free radicals do not contribute to oleic acid lung injury in the early stages.

Surfactant lavage with lidocaine improves pulmonary function in piglets after HCl-induced acute lung injury

Acute respiratory distress syndrome (ARDS) is associated with significant morbidity and mortality. The pathophysiology of ARDS includes abnormalities of surfactant function as well as pulmonary inflammation. Immunomodulating drugs, like Lidocaine, have shown some success in decreasing inflammation in ARDS. We attempted to combine surfactant lavage's ability to reverse the surfactant dysfunction, while acting as a vehicle to deliver Lidocaine. Gravity-driven surfactant (Infasurf) lavage (35 ml/kg) was administered alone or mixed with Lidocaine after severe HCl acid injury (0.3 N; 3 cc/kg) in neonatal piglets. Treatment groups included: control (C) ( n = 5), surfactant lavage (SL) (35 ml/kg-diluted Infasurf) ( n = 7) and SL mixed with Lidocaine (SL+L) ( n = 7). About 26-27% of the lavage was retained (phospholipid 73-74 mg/kg; Lidocaine 1.8 mg/kg). Oxygenation progressively increased in the SL and SL+L groups over the 4-hour period (at 240 min: C = 99 +/- 14; SL = 154 +/- 39; SL+L = 230 +/- 40 mmHg) ( p < 0.05). PaCO(2) increased in all groups from 43 +/- 0.3 to 55 +/- 0.7 mmHg. Only SL+L showed a reduction in PaCO(2) (at 240 min: C = 54 +/- 4; SL = 53 +/- 7; SL+L = 49 +/- 2 mmHg) ( p < 0.05). Finally, SL and SL + L had superior characteristics during the quasi-static pressure volume (PV) procedure as compared to Control ( p < 0.05). In our HCl ALI model, SL improved oxygenation and quasi-static lung compliance over C. The pulmonary function effects of SL were further enhanced by the addition of Lidocaine to the surfactant suspension. Combining therapeutic agents with surfactant lavage may be an effective strategy in ALI.

Elastase inhibition reduced death associated with acid aspiration-induced lung injury in hamsters

This study examined whether the specific inhibition of neutrophil elastase by sivelestat sodium hydrate (sivelestat) reduced deaths associated with severe acute lung injury after hydrochloric acid (HCl) aspiration in hamsters. Animals that received a single intratracheal instillation of HCl (0.2 N, 200 microL) time-dependently died by occlusion of their trachea with inflammatory exudate. In a time course study, these animals developed severe lung injury, peaking 12 to 24 h after HCl instillation, as indicated by hemorrhage and a massive increase in the protein concentration of bronchoalveolar lavage fluid. These changes were closely correlated with neutrophil elastase activity in bronchoalveolar lavage fluid. Sivelestat (0.01, 0.1 and 1 mg/kg/h), when intravenously infused during the first 48 h post-HCl instillation, dose-dependently reduced death in HCl-instilled hamsters. In a separate experiment, analysis of bronchoalveolar lavage fluid parameters and partial pressure of arterial oxygen (PaO(2)) 8 h post-HCl instillation showed that sivelestat at 1 mg/kg/h, i.v. significantly improved both bronchoalveolar lavage fluid parameters and PaO(2) levels with evidence of the inhibition of neutrophil elastase activity in bronchoalveolar lavage fluid. These results suggest that neutrophil elastase plays a significant role in this type of severe acute lung injury that leads to death by respiratory failure.

Partial liquid ventilation for the prevention of mortality and morbidity in paediatric acute lung injury and acute respiratory distress syndrome

BACKGROUND

Acute lung injury, and acute respiratory distress syndrome, are syndromes of severe respiratory failure. Children with acute lung injury or acute respiratory syndrome have high mortality and significant morbidity. Partial liquid ventilation is proposed as a less injurious form of respiratory support for these children. Uncontrolled studies in adults have shown improvement in gas exchange and lung compliance with partial liquid ventilation A single uncontrolled study in six children with acute respiratory syndrome showed some improvement in gas exchange during three hours of partial liquid ventilation.

OBJECTIVES

To assess whether partial liquid ventilation reduces either mortality or morbidity, or both, in children with acute lung injury or acute respiratory syndrome.

SEARCH STRATEGY

We searched The Cochrane Central Register of Controlled Trials (CENTRAL), The Cochrane Library issue 2, 2003; MEDLINE (1966 to April 2003); and CINAHL (1982 to April 2003); intensive care journals and conference proceedings; reference lists and 'grey literature'.

SELECTION CRITERIA

Randomized controlled trials which compared partial liquid ventilation with other forms of ventilation, in children (28 days - 18 years) with acute lung injury or acute respiratory syndrome, reporting one or more of the following: mortality; duration of mechanical ventilation, respiratory support, oxygen therapy, stay in the intensive care unit, or stay in hospital; infection; or long term cognitive impairment or neurodevelopmental progress or other long term morbidities.

DATA COLLECTION AND ANALYSIS

Two reviewers independently evaluated the quality of the relevant studies and extracted the data from the included studies.

MAIN RESULTS

Only one study enrolling 182 patients (only reported as an abstract in conference proceedings) was identified and found eligible for inclusion: the authors report only limited results. The trial was stopped prematurely and therefore under-powered to detect any significant differences. The only outcome of clinical significance available was 28 day mortality: there was no statistically significant difference between groups with a relative risk for 28 day mortality in the partial liquid ventilation group of 1.54 (95% confidence intervals of 0.82 to 2.9).

REVIEWERS' CONCLUSIONS

There is no evidence from randomized controlled trials to support or refute the use of partial liquid ventilation in children with acute lung injury or acute respiratory syndrome: adequately powered, high quality randomized controlled trials are still needed to assess its efficacy. Clinically relevant outcome measures should be assessed (mortality at discharge and later, duration of respiratory support and hospital stay, and long-term neurodevelopmental outcomes) and the studies should be published in full.

Understanding the roles of the transcription factors nuclear factor-kappaB and hypoxia-inducible factor-1alpha in lung injury

The role of oxidative stress in regulating transcription factors and specific gene responses in critical illness is a new and emerging area. A better understanding of the proinflammatory oxidant stimuli of reactive oxygen species generation and how this generates the clinical phenotype of acute lung injury by regulating gene expression may allow the development of new therapeutic strategies. In his review John Haddad describes the present data and role for transcription factors nuclear factor-κB and hypoxia-inducible factor-1α in acute lung injury.

Corticosteroids in ARDS. An evidence-based review

In general, a rule for corticosteroids in preventing or relieving the acute respiratory distress syndrome (ARDS) has yet to be established, although these drugs are indicated for conditions such as Pneumocystis carinii pneumonia. High-dose corticosteroids have not been shown to reduce mortality through their anti-inflammatory properties when given early to patients with sepsis, septic shock, or ARDS. Corticosteroids have been shown, however, to reduce mortality in patients with late ARDS only in one small, inconclusive study. More recent investigators have focused on the usefulness of low-dose corticosteroids in reducing mortality in patients with sepsis or septic shock who may have relative adrenal insufficiency, but these studies also are inconclusive, and it is unclear that low-dose corticosteroids affect the development of ARDS in these patients.