A trial of nebulised heparin to limit lung injury following cardiac surgery

Adjunctive Therapies in Acute Respiratory Distress Syndrome

Despite significant advances in understanding acute respiratory distress syndrome (ARDS), mortality rates remain high. The appropriate use of adjunctive therapies can improve outcomes, particularly for patients with moderate to severe hypoxia. In this review, the authors discuss the evidence basis behind prone positioning, recruitment maneuvers, neuromuscular blocking agents, corticosteroids, pulmonary vasodilators, and extracorporeal membrane oxygenation and considerations for their use in individual patients and specific clinical scenarios. Because the heterogeneity of ARDS poses challenges in finding universally effective treatments, an individualized approach and continued research efforts are crucial for optimizing the utilization of adjunctive therapies and improving patient outcomes.

The effect of nebulized heparin on clinical outcomes in mechanically ventilated patients: a meta-analysis and review of the literature

OBJECTIVE

To determine the relationship between use of nebulized heparin and clinical outcomes in mechanically ventilated patients.

METHODS

The Medline, Embase, Web of Science, Cochrane Library, and PubMed databases were searched for relevant randomized controlled trials (RCTs), published between database inception and May 2022. Primary outcomes were intensive care unit (ICU) length of stay and in-hospital mortality; secondary outcomes included duration of mechanical ventilation, ventilator-free days (VFDs) in 28 days, and length of hospitalization. The study protocol was registered on PROSPERO (registration No: CRD42022345533).

RESULTS

A total of eight RCTs (651 patients) were included. Nebulized heparin was associated with reduced ICU length of stay (six studies; mean difference [MD] -1.10, 95% confidence interval [CI] -1.87, -0.33, I2 = 76%), reduced duration of mechanical ventilation (two studies; MD -2.63, 95% CI -3.68, -1.58, I2 = 92%) and increased VFDs in 28 days (two studies; MD 4.22, 95% CI 1.10, 7.35, I2 = 18%), without increased incidence of adverse events, such as bleeding; but was not associated with a reduction in length of hospitalization (three studies; MD -1.00, 95% CI -2.90, -0.90, I2 = 0%) or in-hospital mortality (five studies; odds ratio 1.10, 95% CI 0.69, 1.77, I2 = 0%).

CONCLUSION

Nebulized heparin reduces ICU length of stay and duration of mechanical ventilation in mechanically ventilated patients, but has no effect on length of hospitalization or mortality.

Pharmacology of Heparin and Related Drugs: An Update

Heparin has been used extensively as an antithrombotic and anticoagulant for close to 100 years. This anticoagulant activity is attributed mainly to the pentasaccharide sequence, which potentiates the inhibitory action of antithrombin, a major inhibitor of the coagulation cascade. More recently it has been elucidated that heparin exhibits anti-inflammatory effect via interference of the formation of neutrophil extracellular traps and this may also contribute to heparin's antithrombotic activity. This illustrates that heparin interacts with a broad range of biomolecules, exerting both anticoagulant and nonanticoagulant actions. Since our previous review, there has been an increased interest in these nonanticoagulant effects of heparin, with the beneficial role in patients infected with SARS2-coronavirus a highly topical example. This article provides an update on our previous review with more recent developments and observations made for these novel uses of heparin and an overview of the development status of heparin-based drugs. SIGNIFICANCE STATEMENT: This state-of-the-art review covers recent developments in the use of heparin and heparin-like materials as anticoagulant, now including immunothrombosis observations, and as nonanticoagulant including a role in the treatment of SARS-coronavirus and inflammatory conditions.

Inhaled nebulised unfractionated heparin (UFH) for the treatment of hospitalised patients with COVID-19: A randomised controlled pilot study

There is a strong scientific rationale to use nebulised unfractionated heparin (UFH) in treating patients with COVID-19. This pilot study investigated whether nebulised UFH was safe and had any impact on mortality, length of hospitalisation and clinical progression, in the treatment of hospitalised patients with COVID-19. This parallel group, open label, randomised trial included adult patients with confirmed SARS-CoV-2 infection admitted to two hospitals in Brazil. One hundred patients were planned to be randomised to either "standard of care" (SOC) or SOC plus nebulized UFH. The trial was stopped after randomisation of 75 patients due to falling COVID-19 hospitalisation rates. Significance tests were 1-sided test (10% significance level). The key analysis populations were intention to treat (ITT) and modified ITT (mITT) which excluded (from both arms) subjects admitted to ITU or who died within 24 h of randomisation. In the ITT population (n = 75), mortality was numerically lower for nebulised UFH (6 out of 38 patients; 15.8%) versus SOC (10 out of 37 patients; 27.0%), but not statistically significant; odds ratio (OR) 0.51, p = 0.24. However, in the mITT population, nebulised UFH reduced mortality (OR 0.2, p = 0.035). Length of hospital stay was similar between groups, but at day 29, there was a greater improvement in ordinal score following treatment with UFH in the ITT and mITT populations (p = 0.076 and p = 0.012 respectively), while mechanical ventilation rates were lower with UFH in the mITT population (OR 0.31; p = 0.08). Nebulised UFH did not cause any significant adverse events. In conclusion, nebulised UFH added to SOC in hospitalised patients with COVID-19 was well tolerated and showed clinical benefit, particularly in patients who received at least 6 doses of heparin. This trial was funded by The J.R. Moulton Charity Trust and registered under REBEC RBR-8r9hy8f (UTN code: U1111-1263-3136).

Pharmacologic therapies of ARDS: From natural herb to nanomedicine

Acute respiratory distress syndrome (ARDS) is a common critical illness in respiratory care units with a huge public health burden. Despite tremendous advances in the prevention and treatment of ARDS, it remains the main cause of intensive care unit (ICU) management, and the mortality rate of ARDS remains unacceptably high. The poor performance of ARDS is closely related to its heterogeneous clinical syndrome caused by complicated pathophysiology. Based on the different pathophysiology phases, drugs, protective mechanical ventilation, conservative fluid therapy, and other treatment have been developed to serve as the ARDS therapeutic methods. In recent years, there has been a rapid development in nanomedicine, in which nanoparticles as drug delivery vehicles have been extensively studied in the treatment of ARDS. This study provides an overview of pharmacologic therapies for ARDS, including conventional drugs, natural medicine therapy, and nanomedicine. Particularly, we discuss the unique mechanism and strength of nanomedicine which may provide great promises in treating ARDS in the future.

XueFu ZhuYu Decoction Alleviates Cardiopulmonary Bypass-Induced NLRP3 Inflammasome-Dependent Pyroptosis by Inhibiting IkB-α/NF-κB Pathway in Acute Lung Injury Rats

XueFu ZhuYu Decoction (XFZYD) is an effective prescription that is widely used to improve blood circulation by removing blood stasis. This study aimed to investigate the effects and the underlying molecular mechanisms of XFZYD on lung pyroptosis in cardiopulmonary bypass- (CPB-) induced acute lung injury (ALI) rats. A rat model of ALI was induced by CPB treatment after XFZYD, Ac-YVAD-CMK, and Bay-11-7082 administration. The respiratory index (RI) and oxygenation index (OI) were determined at each time point. The levels of interleukin (IL)-1β, IL-6, IL-18, and TNF-α in serum and lung were measured by enzyme-linked immunosorbent assays (ELISA). Moreover, the protein levels, neutrophil counts, and total cell of bronchoalveolar lavage fluid (BALF) were detected. Additionally, Myeloperoxidase (MPO) expression was detected by immunohistochemical assay. Lung injury was evaluated with the wet/dry (W/D) ratio and pathologic changes, respectively. Besides, the expression of NLRP3 inflammasome and IkB-α/NF-κB pathway proteins was estimated by immunofluorescence, quantitative real-time PCR (qRT-PCR), and Western blotting assays, respectively. XFZYD pretreatment significantly ameliorated pulmonary ventilation function and reduced the CPB-induced lung histopathological injury, inflammatory cell infiltration in BALF and lung, and the apoptosis of lung cells. Interestingly, XFZYD decreased the CPB-induced NLRP3, ASC, Caspase-1 p20, Pro-GSDMD, GSDMD p30, IL-18, IL-1β p-P65, and p-IKBα mRNA or protein levels in lung tissues in ALI model rats. In summary, these findings suggest that XFZYD effectively mitigates NLRP3 inflammasome-dependent pyroptosis in CPB-induced ALI model rats, possibly by inhibiting the IkB-α/NF-κB pathway in the lung.

Can nebulised HepArin Reduce morTality and time to Extubation in Patients with COVID-19 Requiring invasive ventilation Meta-Trial (CHARTER-MT): Protocol and Statistical Analysis Plan for an investigator-initiated international meta-trial of prospective randomised clinical studies

There is significant interest in the potential for nebulised unfractionated heparin (UFH) as a novel therapy for patients with COVID-19 induced acute hypoxaemic respiratory failure requiring invasive ventilation. The scientific and biological rationale for nebulised heparin stems from the evidence for extensive activation of coagulation resulting in pulmonary microvascular thrombosis in COVID-19 pneumonia. Nebulised delivery of heparin to the lung may limit alveolar fibrin deposition and thereby limit progression of lung injury. Importantly, laboratory studies show that heparin can directly inactivate the SARS-CoV-2 virus, thereby prevent its entry into and infection of mammalian cells. UFH has additional anti-inflammatory and mucolytic properties that may be useful in this context. METHODS AND INTERVENTION: The Can nebulised HepArin Reduce morTality and time to Extubation in Patients with COVID-19 Requiring invasive ventilation Meta-Trial (CHARTER-MT) is a collaborative prospective individual patient data analysis of on-going randomised controlled clinical trials across several countries in 5 continents, examining the effects of inhaled heparin in patients with COVID-19 requiring invasive ventilation on various endpoints. Each constituent study will randomise patients with COVID-19 induced respiratory failure requiring invasive ventilation. Patients are randomised to receive nebulised heparin or standard care (open label studies) or placebo (blinded placebo-controlled studies) while under invasive ventilation. Each participating study collect a pre-defined minimum dataset. The primary outcome for the meta-trial is the number of ventilator-free days up to day 28 day, defined as days alive and free from invasive ventilation. ETHICS AND DISSEMINATION: The meta-trial is registered at ClinicalTrials.gov ID NCT04545541. Each contributing study is individually registered and has received approval of the relevant ethics committee or institutional review board. Results of this study will be shared with the WHO, published in scientific journals, and presented at scientific meetings.

Inhaled nebulised unfractionated heparin for the treatment of hospitalised patients with COVID-19: A multicentre case series of 98 patients

OBJECTIVE

To determine the safety and efficacy-potential of inhaled nebulised unfractionated heparin (UFH) in the treatment of hospitalised patients with COVID-19.

METHODS

Retrospective, uncontrolled multicentre single-arm case series of hospitalised patients with laboratory-confirmed COVID-19, treated with inhaled nebulised UFH (5000IU 8-hourly, 10000IU 4-hourly, or 25000IU 6-hourly) for 6±3 (mean±SD) days. Outcomes were APTT before treatment (baseline) and highest-level during treatment (peak), and adverse events including bleeding. Exploratory efficacy outcomes were oxygenation, assessed by SpO2 to FiO2 (S/F) ratio and FiO2, and the WHO modified ordinal clinical scale (MOCS).

RESULTS

98 patients were included. In patients on stable prophylactic or therapeutic systemic anticoagulant therapy but not receiving therapeutic UFH infusion, APTT levels increased from baseline of 34±10 seconds to a peak of 38±11 seconds (p<0.0001). In 3 patients on therapeutic UFH infusion, APTT levels did not significantly increase from baseline of 72±20 to a peak of 84±28 seconds (p=0.17). Two patients had serious adverse events: bleeding gastric ulcer requiring transfusion; thigh haematoma; both were on therapeutic anticoagulation. Minor bleeding occurred in 16 patients, 13 of which were on therapeutic anticoagulation. The S/F ratio and the FiO2 worsened before and improved after commencement of inhaled UFH (change in slope, p<0.001).

CONCLUSION

Inhaled nebulised UFH in hospitalised patients with COVID-19 was safe. Although statistically significant, inhaled nebulised UFH did not produce a clinically relevant increase in APTT (peak values in the normal range). Urgent randomised evaluation of nebulised UFH in patients with COVID-19 is warranted and several studies are currently underway.

Pharmacological and clinical application of heparin progress: An essential drug for modern medicine

Heparin is the earliest and most widely used anticoagulant and antithrombotic drug that is still used in a variety of clinical indications. Since it was discovered in 1916, after more than a century of repeated exploration, heparin has not been replaced by other drugs, but a great progress has been made in its basic research and clinical application. Besides anticoagulant and antithrombotic effects, heparin also has antitumor, anti-inflammatory, antiviral, and other pharmacological activities. It is widely used clinically in cardiovascular and cerebrovascular diseases, lung diseases, kidney diseases, cancer, etc., as the first anticoagulant medicine in COVID-19 exerts anticoagulant, anti-inflammatory and antiviral effects. At the same time, however, it also leads to a lot of adverse reactions, such as bleeding, thrombocytopenia, elevated transaminase, allergic reactions, and others. This article comprehensively reviews the modern research progress of heparin compounds; discusses the structure, preparation, and adverse reactions of heparin; emphasizes the pharmacological activity and clinical application of heparin; reveals the possible mechanism of the therapeutic effect of heparin in related clinical applications; provides evidence support for the clinical application of heparin; and hints on the significance of exploring the wider application fields of heparin.

Nebulised heparin for patients with or at risk of acute respiratory distress syndrome: a multicentre, randomised, double-blind, placebo-controlled phase 3 trial

Background

Mechanical ventilation in intensive care for 48 h or longer is associated with the acute respiratory distress syndrome (ARDS), which might be present at the time ventilatory support is instituted or develop afterwards, predominantly during the first 5 days. Survivors of prolonged mechanical ventilation and ARDS are at risk of considerably impaired physical function that can persist for years. An early pathogenic mechanism of lung injury in mechanically ventilated, critically ill patients is inflammation-induced pulmonary fibrin deposition, leading to thrombosis of the microvasculature and hyaline membrane formation in the air sacs. The main aim of this study was to determine if nebulised heparin, which targets fibrin deposition, would limit lung injury and thereby accelerate recovery of physical function in patients with or at risk of ARDS.

Methods

The Can Heparin Administration Reduce Lung Injury (CHARLI) study was an investigator-initiated, multicentre, double-blind, randomised phase 3 trial across nine hospitals in Australia. Adult intensive care patients on invasive ventilation, with impaired oxygenation defined by a PaO₂/FiO₂ ratio of less than 300, and with the expectation of invasive ventilation beyond the next calendar day were recruited. Key exclusion criteria were heparin allergy, pulmonary bleeding, and platelet count less than 50 X 10⁹/L. Patients were randomly assigned 1:1, with stratification by site and using blocks of variable size and random seed, via a web-based system, to either unfractionated heparin sodium 25 000 IU in 5 mL or identical placebo (sodium chloride 0·9% 5 mL), administered using a vibrating mesh membrane nebuliser every 6 h to day 10 while invasively ventilated. Patients, clinicians, and investigators were masked to treatment allocation. The primary outcome was the Short Form 36 Health Survey Physical Function Score (out of 100) of survivors at day 60. Prespecified secondary outcomes, which are exploratory, included development of ARDS to day 5 among at-risk patients, deterioration of the Murray Lung Injury Score (MLIS) to day 5, mortality at day 60, residence of survivors at day 60, and serious adverse events. Analyses followed the intention-to-treat principle. There was no imputation of missing data. The trial is registered with the Australian and New Zealand Clinical Trials Register, number ACTRN12612000418875 .

Findings

Between Sept 4, 2012, and Aug 23, 2018, 256 patients were randomised. Final follow-up was on Feb 25, 2019. We excluded three patients who revoked consent and one ineligible participant who received no intervention. Of 252 patients included in data analysis, the mean age was 58 years (SD 15), 157 (62%) were men, and 118 (47%) had ARDS. 128 (51%) patients were assigned to the heparin group and 124 (49%) to the placebo group, all of whom received their assigned intervention. Survivors in the heparin group (n=97) had similar SF-36 Physical Function Scores at day 60 compared to the placebo group (n=94; mean 53·6 [SD 31·6] vs 48·7 [35·7]; difference 4·9 [95% CI −4·8 to 14·5]; p=0·32). Compared with the placebo group, the heparin group had fewer cases of ARDS develop to day 5 among the at-risk patients (nine [15%] of 62 patients vs 21 [30%] of 71 patients; hazard ratio 0·46 [95% CI 0·22 to 0·98]; p=0·0431), less deterioration of the MLIS to day 5 (difference −0·14 [–0·26 to −0·02]; p=0·0215), similar day 60 mortality (23 [18%] of 127 patients vs 18 [15%] of 123 patients; odds ratio [OR] 1·29 [95% CI 0·66 to 2·53]; p=0·46), and more day 60 survivors at home (86 [87%] of 99 patients vs 73 [73%] of 100 patients; OR 2·45 [1·18 to 5·08]; p=0·0165). A similar number of serious adverse events occurred in each group (seven [5%] of 128 patients in the heparin group vs three [2%] of 124 patients in the placebo group; OR 2·33 [0·59 to 9·24]; p=0·23), which were a transient increase in airway pressure during nebulisation (n=3 in the heparin group), major non-pulmonary bleeding (n=2 in each group), haemoptysis (n=1 in the heparin group), tracheotomy site bleeding (n=1 in the heparin group), and hypoxaemia during nebulisation (n=1 in the placebo group).

Interpretation

In patients with or at risk of ARDS, nebulised heparin did not improve self-reported performance of daily physical activities, but was well tolerated and exploratory outcomes suggest less progression of lung injury and earlier return home. Further research is justified to establish if nebulised heparin accelerates recovery in those who have or are at risk of ARDS.

Funding

Rowe Family Foundation, TR and RB Ditchfield Medical Research Endowment Fund, Patricia Madigan Charitable Trust, and The J and R McGauran Trust Fund.

INHALEd nebulised unfractionated HEParin for the treatment of hospitalised patients with COVID-19 (INHALE-HEP): Protocol and statistical analysis plan for an investigator-initiated international metatrial of randomised studies

AIMS

Inhaled nebulised unfractionated heparin (UFH) has a strong scientific and biological rationale that warrants urgent investigation of its therapeutic potential in patients with COVID-19. UFH has antiviral effects and prevents the SARS-CoV-2 virus' entry into mammalian cells. In addition, UFH has significant anti-inflammatory and anticoagulant properties, which limit progression of lung injury and vascular pulmonary thrombosis.

METHODS

The INHALEd nebulised unfractionated HEParin for the treatment of hospitalised patients with COVID-19 (INHALE-HEP) metatrial is a prospective individual patient data analysis of on-going randomised controlled trials and early phase studies. Individual studies are being conducted in multiple countries. Participating studies randomise adult patients admitted to the hospital with confirmed SARS-CoV-2 infection, who do not require immediate mechanical ventilation, to inhaled nebulised UFH or standard care. All studies collect a minimum core dataset. The primary outcome for the metatrial is intubation (or death, for patients who died before intubation) at day 28. The secondary outcomes are oxygenation, clinical worsening and mortality, assessed in time-to-event analyses. Individual studies may have additional outcomes.

ANALYSIS

We use a Bayesian approach to monitoring, followed by analysing individual patient data, outcomes and adverse events. All analyses will follow the intention-to-treat principle, considering all participants in the treatment group to which they were assigned, except for cases lost to follow-up or withdrawn.

TRIAL REGISTRATION, ETHICS AND DISSEMINATION

The metatrial is registered at ClinicalTrials.gov ID NCT04635241. Each contributing study is individually registered and has received approval of the relevant ethics committee or institutional review board. Results of this study will be shared with the World Health Organisation, published in scientific journals and presented at scientific meetings.

Targeting coagulation activation in severe COVID-19 pneumonia: lessons from bacterial pneumonia and sepsis

Novel coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), has rapidly spread throughout the world, resulting in a pandemic with high mortality. There are no effective treatments for the management of severe COVID-19 and current therapeutic trials are focused on antiviral therapy and attenuation of hyper-inflammation with anti-cytokine therapy. Severe COVID-19 pneumonia shares some pathological similarities with severe bacterial pneumonia and sepsis. In particular, it disrupts the haemostatic balance, which results in a procoagulant state locally in the lungs and systemically. This culminates in the formation of microthrombi, disseminated intravascular coagulation and multi-organ failure. The deleterious effects of exaggerated inflammatory responses and activation of coagulation have been investigated in bacterial pneumonia and sepsis and there is recognition that although these pathways are important for the host immune response to pathogens, they can lead to bystander tissue injury and are negatively associated with survival. In the past two decades, evidence from preclinical studies has led to the emergence of potential anticoagulant therapeutic strategies for the treatment of patients with pneumonia, sepsis and acute respiratory distress syndrome, and some of these anticoagulant approaches have been trialled in humans. Here, we review the evidence from preclinical studies and clinical trials of anticoagulant treatment strategies in bacterial pneumonia and sepsis, and discuss the importance of these findings in the context of COVID-19.

Nebulised heparin as a treatment for COVID-19: scientific rationale and a call for randomised evidence

Nebulised unfractionated heparin (UFH) has a strong scientific and biological rationale and warrants urgent investigation of its therapeutic potential, for COVID-19-induced acute respiratory distress syndrome (ARDS). COVID-19 ARDS displays the typical features of diffuse alveolar damage with extensive pulmonary coagulation activation resulting in fibrin deposition in the microvasculature and formation of hyaline membranes in the air sacs. Patients infected with SARS-CoV-2 who manifest severe disease have high levels of inflammatory cytokines in plasma and bronchoalveolar lavage fluid and significant coagulopathy. There is a strong association between the extent of the coagulopathy and poor clinical outcomes.The anti-coagulant actions of nebulised UFH limit fibrin deposition and microvascular thrombosis. Trials in patients with acute lung injury and related conditions found inhaled UFH reduced pulmonary dead space, coagulation activation, microvascular thrombosis and clinical deterioration, resulting in increased time free of ventilatory support. In addition, UFH has anti-inflammatory, mucolytic and anti-viral properties and, specifically, has been shown to inactivate the SARS-CoV-2 virus and prevent its entry into mammalian cells, thereby inhibiting pulmonary infection by SARS-CoV-2. Furthermore, clinical studies have shown that inhaled UFH safely improves outcomes in other inflammatory respiratory diseases and also acts as an effective mucolytic in sputum-producing respiratory patients. UFH is widely available and inexpensive, which may make this treatment also accessible for low- and middle-income countries.These potentially important therapeutic properties of nebulised UFH underline the need for expedited large-scale clinical trials to test its potential to reduce mortality in COVID-19 patients.

Emerging pharmacological therapies for ARDS: COVID-19 and beyond

ARDS, first described in 1967, is the commonest form of acute severe hypoxemic respiratory failure. Despite considerable advances in our knowledge regarding the pathophysiology of ARDS, insights into the biologic mechanisms of lung injury and repair, and advances in supportive care, particularly ventilatory management, there remains no effective pharmacological therapy for this syndrome. Hospital mortality at 40% remains unacceptably high underlining the need to continue to develop and test therapies for this devastating clinical condition. The purpose of the review is to critically appraise the current status of promising emerging pharmacological therapies for patients with ARDS and potential impact of these and other emerging therapies for COVID-19-induced ARDS. We focus on drugs that: (1) modulate the immune response, both via pleiotropic mechanisms and via specific pathway blockade effects, (2) modify epithelial and channel function, (3) target endothelial and vascular dysfunction, (4) have anticoagulant effects, and (5) enhance ARDS resolution. We also critically assess drugs that demonstrate potential in emerging reports from clinical studies in patients with COVID-19-induced ARDS. Several therapies show promise in earlier and later phase clinical testing, while a growing pipeline of therapies is in preclinical testing. The history of unsuccessful clinical trials of promising therapies underlines the challenges to successful translation. Given this, attention has been focused on the potential to identify biologically homogenous subtypes within ARDS, to enable us to target more specific therapies ‘precision medicines.’ It is hoped that the substantial number of studies globally investigating potential therapies for COVID-19 will lead to the rapid identification of effective therapies to reduce the mortality and morbidity of this devastating form of ARDS.

Nebulized anticoagulants in lung injury in critically ill patients-an updated systematic review of preclinical and clinical studies

Pneumonia, inhalation trauma and acute respiratory distress syndrome (ARDS), typical causes of lung injury in critically ill patients, are all three characterized by dysregulated inflammation and coagulation in the lungs. Nebulized anticoagulants are thought to have beneficial effects as they could attenuate pulmonary coagulopathy and maybe even affect pulmonary inflammation. A systematic search of the medical literature was performed using terms referring to aspects of the condition ('pneumonia', 'inhalation trauma' and 'ARDS'), the intervention ('nebulized', 'vaporized', and 'aerosolized') and anticoagulants limited to agents that are commercially available and frequently given or tested in critically ill patients ['heparin', 'danaparoid', 'activated protein C' (APC), 'antithrombin' (AT) and 'tissue factor pathway inhibitor' (TFPI)]. The systematic search identified 16 articles reporting on preclinical studies and 11 articles reporting on human trials. All nebulized anticoagulants attenuate pulmonary coagulopathy in preclinical studies using various models for lung injury, but the effects on inflammation are less consistent. Nebulized heparin, danaparoid and TFPI, but not APC and AT also reduced systemic coagulation. Nebulized heparin in lung injury patients shows contradictory results, and there is concern over systemic side effects of this strategy. Future studies need to focus on the way to nebulize anticoagulants, as well as on efficient but safe dosages, and other side effects.