Acute respiratory distress syndrome: the heart side of the moon

M1 Macrophage-Targeted Curcumin Nanocrystals with l-Arginine-Modified for Acute Lung Injury by Inhalation

Acute Lung Injury/Acute Respiratory Distress Syndrome (ALI/ARDS) with clinical manifestations of respiratory distress and hypoxemia remains a significant cause of respiratory failure, boasting a persistently high incidence and mortality rate. Given the central role of M1 macrophages in the pathogenesis of acute lung injury (ALI), this study utilized the anti-inflammatory agent curcumin as a model drug. l-arginine (L-Arg) was employed as a targeting ligand, and chitosan was initially modified with l-arginine. Subsequently, it was utilized as a surface modifier to prepare inhalable nano-crystals loaded with curcumin (Arg-CS-Cur), aiming for specific targeting of pulmonary M1 macrophages. Compared with unmodified chitosan-curcumin nanocrystals (CS-Cur), Arg-CS-Cur exhibited higher uptake in vitro by M1 macrophages, as evidenced by flow cytometry showing the highest fluorescence intensity in the Arg-CS-Cur group (P < 0.01). In vivo accumulation was greater in inflamed lung tissues, as indicated by small animal imaging demonstrating higher lung fluorescence intensity in the DiR-Arg-CS-Cur group compared to the DiR-CS-Cur group in the rat ALI model (P < 0.05), peaking at 12 h. Moreover, Arg-CS-Cur demonstrated enhanced therapeutic effects in both LPS-induced RAW264.7 cells and ALI rat models. Specifically, treatment with Arg-CS-Cur significantly suppressed NO release and levels of TNF-α and IL-6 in RAW264.7 cells (p < 0.01), while in ALI rat models, expression levels of TNF-α and IL-6 in lung tissues were significantly lower than those in the model group (P < 0.01). Furthermore, lung tissue damage was significantly reduced, with histological scores significantly lower than those in the CS-Cur group (P < 0.01). In conclusion, these findings underscore the targeting potential of l-arginine-modified nanocrystals, which effectively enhance curcumin concentration in inflammatory environments by selectively targeting M1 macrophages. This study thus introduces novel perspectives and theoretical support for the development of targeted therapeutic interventions for acute inflammatory lung diseases, including ALI/ARDS.

Leveraging Hypotension Prediction Index to Forecast LPS-Induced Acute Lung Injury and Inflammation in a Porcine Model: Exploring the Role of Hypoxia-Inducible Factor in Circulatory Shock

Acute respiratory distress syndrome (ARDS) is a critical illness in critically unwell patients, characterized by refractory hypoxemia and shock. This study evaluates an early detection tool and investigates the relationship between hypoxia and circulatory shock in ARDS, to improve diagnostic precision and therapy customization. We used a porcine model, inducing ARDS with mechanical ventilation and intratracheal plus intravenous lipopolysaccharide (LPS) injection. Hemodynamic changes were monitored using an Acumen IQ sensor and a ForeSight Elite sensor connected to the HemoSphere platform. We evaluated tissue damage, inflammatory response, and hypoxia-inducible factor (HIF) alterations using enzyme-linked immunosorbent assay and immunohistochemistry. The results showed severe hypotension and increased heart rates post-LPS exposure, with a notable rise in the hypotension prediction index (HPI) during acute lung injury (p = 0.024). Tissue oxygen saturation dropped considerably in the right brain region. Interestingly, post-injury HIF-2α levels were lower at the end of the experiment. Our findings imply that the HPI can effectively predict ARDS-related hypotension. HIF expression levels may serve as possible markers of rapid ARDS progression. Further research should be conducted on the clinical value of this novel approach in critical care, as well as the relationship between the HIF pathway and ARDS-associated hypotension.

A framework for heart-lung interaction and its application to prone position in the acute respiratory distress syndrome

While both cardiac output (Qcirculatory) and right atrial pressure (PRA) are important measures in the intensive care unit (ICU), they are outputs of the system and not determinants. That is to say, in a model of the circulation wherein venous return and cardiac function find equilibrium at an 'operating point' (OP, defined by the PRA on the x-axis and Qcirculatory on the y-axis) both the PRA and Qcirculatory are, necessarily, dependent variables. A simplified geometrical approximation of Guyton's model is put forth to illustrate that the independent variables of the system are: 1) the mean systemic filling pressure (PMSF), 2) the pressure within the pericardium (PPC), 3) cardiac function and 4) the resistance to venous return. Classifying independent and dependent variables is clinically-important for therapeutic control of the circulation. Recent investigations in patients with acute respiratory distress syndrome (ARDS) have illuminated how PMSF, cardiac function and the resistance to venous return change when placing a patient in prone. Moreover, the location of the OP at baseline and the intimate physiological link between the heart and the lungs also mediate how the PRA and Qcirculatory respond to prone position. Whereas turning a patient from supine to prone is the focus of this discussion, the principles described within the framework apply equally-well to other more common ICU interventions including, but not limited to, ventilator management, initiating vasoactive medications and providing intravenous fluids.

Optic nerve sheath diameter is associated with outcome in severe Covid-19

Neurological symptoms are common in Covid-19 and cerebral edema has been shown post-mortem. The mechanism behind this is unclear. Elevated intracranial pressure (ICP) has not been extensively studied in Covid-19. ICP can be estimated noninvasively with measurements of the optic nerve sheath diameter (ONSD). We performed a cohort study with ONSD ultrasound measurements in severe cases of Covid-19 at an intensive care unit (ICU). We measured ONSD with ultrasound in adults with severe Covid-19 in the ICU at Karolinska University Hospital in Sweden. Patients were classified as either having normal or elevated ONSD. We compared ICU length of stay (ICU-LOS) and 90 day mortality between the groups. 54 patients were included. 11 of these (20.4%) had elevated ONSD. Patients with elevated ONSD had 12 days longer ICU-LOS (95% CI 2 to 23 p = 0.03) and a risk ratio of 2.3 for ICU-LOS ≥ 30 days. There were no significant differences in baseline data or 90 day mortality between the groups. Elevated ONSD is common in severe Covid-19 and is associated with adverse outcome. This may be caused by elevated ICP. This is a clinically important finding that needs to be considered when deciding upon various treatment strategies.

Management of the Critically Ill Patient with Pulmonary Arterial Hypertension and Right Heart Failure

Right ventricular (RV) failure is a recognized complication of pulmonary hypertension (PH). Pregnancy and surgery represent unique challenges to the patient with PH and require input from an interprofessional team. Approach to treatment must embrace sound physiologic principles that are based on optimization of RV preload, contractility, and afterload to improve cardiac function and tissue perfusion before the onset of multiorgan dysfunction. Failure of medical therapy needs to be recognized before the onset of irreversible shock. When appropriate, eligible patients should be considered for mechanical circulatory support as a bridge to recovery or transplantation.

Effect of prone position in patients with acute respiratory distress syndrome supported by venovenous extracorporeal membrane oxygenation: a retrospective cohort study

Background

The application of prone position (PP) in acute respiratory distress syndrome (ARDS) supported by venovenous extracorporeal membrane oxygenation (VV-ECMO) is controversial.

Objectives

To evaluate the safety and efficacy of application of PP during VV-ECMO in patients with ARDS.

Methods

This was a single-center, retrospective study of patients who met the Berlin definition of ARDS, and were supported with VV-ECMO. We divided the patients into two groups. The prone group included patients who were supported by VV-ECMO, and experienced at least one period of PP, while those without PP during VV-ECMO were defined as the supine group. Propensity score matching (PSM) at a ratio of 1:1 was introduced to minimize potential confounders. The primary outcomes were the complications of PP and the change of arterial oxygen pressure/fraction of the inspiration (PaO₂/FiO₂) ratio after PP. The secondary outcomes were hospital survival, ICU survival, and ECMO weaning rate.

Results

From April 2013 to October 2020, a total of 91 patients met the diagnostic criteria of ARDS who were supported with ECMO. 38 patients (41.8%) received at least one period of PP during ECMO, while 53 patients (58.2%) were maintained in supine position during ECMO. 22 minor complications were reported in the prone group and major complications were not found. The other ECMO-related complications were similar between two groups. The PaO₂/FiO₂ ratio significantly improved after PP compared with before (174.50 (132.40–228.25) mmHg vs. 158.00 (122.93–210.33) mmHg, p < 0.001). PSM selected 25 pairs of patients with similar characteristics. Hospital survival or ICU survival did not differ between the two groups (40% vs. 28%, p = 0.370; 40% vs. 32%, p = 0.556). Significant difference of ECMO weaning rate between two groups was not found (56% vs. 32%, p = 0.087).

Conclusions

PP during VV-ECMO was safe and could improve oxygenation. A large-scale and well-designed RCT is needed in the future.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-022-02026-7.

Various Aspects of Non-Invasive Ventilation in COVID-19 Patients: A Narrative Review

Non-invasive ventilation (NIV) is primarily used to treat acute respiratory failure. However, it has broad applications to manage a range of other diseases successfully. The main advantage of NIV lies in its capability to provide the same physiological effects as invasive ventilation while avoiding the placement of an artificial airway and its associated life-threatening complications. The war on the COVID-19 pandemic is far from over. The present narrative review aimed at identifying various aspects of NIV usage, in COVID-19 and other patients, such as the onset time, mode, setting, positioning, sedation, and types of interface. A search for articles published from May 2020 to April 2021 was conducted using MEDLINE, PMC central, Scopus, Web of Science, Cochrane Library, and Embase databases. Of the initially identified 5,450 articles, 73 studies and 24 guidelines on the use of NIV were included. The search was limited to studies involving human cases and English language articles. Despite several reported benefits of NIV, the evidence on the use of NIV in COVID-19 patients does not yet fully support its routine use.

Levosimendan Ameliorates Cardiopulmonary Function but Not Inflammatory Response in a Dual Model of Experimental ARDS

The calcium sensitiser levosimendan, which is used as an inodilator to treat decompensated heart failure, may also exhibit anti-inflammatory properties. We examined whether treatment with levosimendan improves cardiopulmonary function and is substantially beneficial to the inflammatory response in acute respiratory response syndrome (ARDS). Levosimendan was administered intravenously in a new experimental porcine model of ARDS. For comparison, we used milrinone, another well-known inotropic agent. Our results demonstrated that levosimendan intravenously improved hemodynamics and lung function in a porcine ARDS model. Significant beneficial alterations in the inflammatory response and lung injury were not detected.

Mortality of right ventricular dysfunction in patients with acute respiratory distress syndrome subjected to lung protective ventilation: A systematic review and meta-analysis

BACKGROUND

The impact of right ventricular dysfunction(RVD) on the prognosis of acute respiratory distress syndrome(ARDS) patients is controversial.

OBJECTIVES

The objectives of this systematic review and meta-analysis was to investigate whether RVD or pulmonary vascular dysfunction are associated with increased mortality in patients with ARDS.

METHODS

We searched Pubmed, Embase, Cochrane Library, Wanfang Data, CNKI, and the WHO Clinical Trial Registry for studies of RVD or pulmonary vascular dysfunction in patients with ARDS.

RESULTS

The presence of RVD or pulmonary vascular dysfunction in patients with ARDS was associated with an increase in mortality (OR = 1.68, 95% CI = 1.21-2.32, P = 0.069, I² = 40.8%). Subgroup analyses obtained similar results. Funnel plots and the Egger's test indicated no publication bias, and sensitivity analyses determined that the results were stable.

CONCLUSION

The prognosis of patients with ARDS and RVD or pulmonary vascular dysfunction is worse than that of ARDS patients without RVD or pulmonary vascular dysfunction.

Right Ventricular Dysfunction in Patients With COVID-19: A Systematic Review and Meta-analysis

OBJECTIVE

This systematic review and meta-analysis aimed to describe the features of right ventricular impairment and pulmonary hypertension in coronavirus disease (COVID-19) and assess their effect on mortality.

DESIGN

The authors carried out a systematic review and meta-analysis of observational studies.

SETTING

The authors performed a search through PubMed, the International Clinical Trials Registry Platform, and the Cochrane Library for studies reporting right ventricular dysfunction in patients with COVID-19 and outcomes.

PARTICIPANTS

The search yielded nine studies in which the appropriate data were available.

INTERVENTIONS

Pooled odds ratios were calculated according to the random-effects model.

MEASUREMENTS AND MAIN RESULTS

Overall, 1,450 patients were analyzed, and half of them were invasively ventilated. Primary outcome was mortality at the longest follow-up available. Mortality was 48.5% versus 24.7% in patients with or without right ventricular impairment (n = 7; OR = 3.10; 95% confidence interval [CI] 1.72-5.58; p = 0.0002), 56.3% versus 30.6% in patients with or without right ventricular dilatation (n = 6; OR = 2.43; 95% CI 1.41-4.18; p = 0.001), and 52.9% versus 14.8% in patients with or without pulmonary hypertension (n = 3; OR = 5.75; 95% CI 2.67-12.38; p < 0.001).

CONCLUSION

Mortality in patients with COVID-19 requiring respiratory support and with a diagnosis of right ventricular dysfunction, dilatation, or pulmonary hypertension is high. Future studies should highlight the mechanisms of right ventricular derangement in COVID-19, and early detection of right ventricular impairment using ultrasound might be important to individualize therapies and improve outcomes.

Heart-Protective Mechanical Ventilation in Postoperative Cardiosurgical Patients

BACKGROUND

This study compared the hemodynamic effects and gas exchange under several different ventilator settings-with regard to tidal volume, respiratory rate, and end-expiratory pressure-in patients after coronary artery bypass grafting (CABG).

METHODS

Prospective interventional cohort study with a controlled group in a single cardiosurgical ICU involving 119 patients following on-pump CABG surgery. During the 1st postoperative hour, the intervention group patients were ventilated with Vt 10 ml × kg-1, RR 14/min, PEEP 5 cmH2O ("conventional ventilation"). During the 2nd hour, RR was reduced to 8/min ("reduced RR ventilation"). At 3 hrs, Vt was decreased to 6 ml × kg-1, RR returned to 14/min, and PEEP increased to 10 cmH2O ("low Vt-high PEEP ventilation").

RESULTS

Patients in the "low Vt-high PEEP" ventilation period showed significantly lower alveolar ventilation and thoraco-pulmonary compliance than during "reduced RR" ventilation. Mean airway pressure and Vds/Vt peaked during low Vt-high PEEP ventilation; however, driving pressure was lower. Vt decrease and PEEP increase did not lead to oxygenation improvement and worsened CO2 elimination. Hemodynamically, the study revealed significant cardiac output decrease during low Vt-high PEEP ventilation. In 23.2% of patients, catecholamine therapy was initiated.

CONCLUSIONS

In postoperative cardiosurgical patients, MV with Vt 6 ml × kg-1 and PEEP 10 cm H2O is characterized by worsened oxygenation and elimination of CO2 and a less favorable hemodynamic profile than ventilation with Vt 10 ml × kg-1 and PEEP 5 cmH2O. New and Noteworthy. (i) Patients after CABG may be especially sensitive to low tidal volume and increased PEEP as it negatively affects hemodynamic profile by means of the right heart preload decrease and afterload increase. (ii) Mechanical ventilation settings aiming to minimize mean airway pressure reduce the negative effects of positive inspiratory pressure and are favorable for hemodynamics.

Right Ventricular Damage in COVID-19: Association Between Myocardial Injury and COVID-19

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2, is a global pandemic. It has resulted in considerable morbidity and mortality around the world. The respiratory system is the main system invaded by the virus involved in COVID-19. In addition to typical respiratory manifestations, a certain proportion of severe COVID-19 cases present with evidence of myocardial injury, which is associated with excessive mortality. With availability of an increasing amount of imaging data, right ventricular (RV) damage is prevalent in patients with COVID-19 and myocardial injury, while left ventricular damage is relatively rare and lacks specificity. The mechanisms of RV damage may be due to increased RV afterload and decreased RV contractility caused by various factors, such as acute respiratory distress syndrome, pulmonary thrombosis, direct viral injury, hypoxia, inflammatory response and autoimmune injury. RV dysfunction usually indicates a poor clinical outcome in patients with COVID-19. Timely and effective treatment is of vital importance to save patients' lives as well as improve prognosis. By use of echocardiography or cardiovascular magnetic resonance, doctors can find RV dilatation and dysfunction early. By illustrating the phenomenon of RV damage and its potential pathophysiological mechanisms, we will guide doctors to give timely medical treatments (e.g., anticoagulants, diuretics, cardiotonic), and device-assisted therapy (e.g., mechanical ventilation, extracorporeal membrane oxygenation) when necessary for these patients. In the paper, we examined the latest relevant studies to investigate the imaging features, potential mechanisms, and treatments of myocardial damage caused by COVID-19. RV damage may be an association between myocardial damage and lung injury in COVID-19. Early assessment of RV geometry and function will be helpful in aetiological determination and adjustment of treatment options.

The overlooked chamber in coronavirus disease 2019

Coronavirus disease 2019 (COVID-19) causes a pandemic around the globe. Debilitating and even deadly complications have occurred to the millions. A recent study reported 31% of right ventricular dilation in the hospitalized COVID-19 patients, which is significantly associated with the mortality. Therefore, we sought to search for the lines of evidence in the literature that COVID-19 may contribute to right heart dysfunction. The relevant literature and data from PubMed, Embase, Cochrane Library databases, and Web of Science were searched using the MeSH terms including 'COVID-19', 'SARS-CoV-2', 'novel coronavirus pneumonia', 'novel coronavirus', 'right heart failure', 'right heart dysfunction', 'pulmonary hypertension', 'pulmonary embolism', and various combinations. The collected literature and data were sorted and summarized. Literature reports that angiotensin-converting enzyme 2 (ACE2) is the host receptor mediating the cell entry of severe acute respiratory syndrome coronavirus 2. Clinical and experimental evidence shows that loss of function of ACE2 aggravates pulmonary hypertension and gain of function of ACE2 exerts protection on cardiopulmonary circulation. Moreover, the patients with COVID-19 are more susceptible to pulmonary embolism and severe pneumonia-induced acute respiratory distress syndrome. Therefore, COVID-19 may cause right heart dysfunction by inducing pulmonary hypertension, pulmonary embolism, and acute respiratory distress syndrome. Particular attention should be paid to the function of the right heart, the overlooked chamber in COVID-19. Blood gas analysis, laboratory test of cardiac injury markers, physical examination, and echocardiography should be performed to identify right heart failure as early as possible. Once the right heart failure is confirmed, the therapeutic modalities following the guidelines of European Society of Cardiology should be employed to reduce mortality.

[Ultrasound in the management of the critically ill patient with SARS-CoV-2 infection (COVID-19): narrative review]

The clinical picture of SARS-CoV-2 infection (COVID-19) is characterized in its more severe form, by an acute respiratory failure which can worsen to pneumonia and acute respiratory distress syndrome (ARDS) and get complicated with thrombotic events and heart dysfunction. Therefore, admission to the Intensive Care Unit (ICU) is common. Ultrasound, which has become an everyday tool in the ICU, can be very useful during COVID-19 pandemic, since it provides the clinician with information which can be interpreted and integrated within a global assessment during the physical examination. A description of some of the potential applications of ultrasound is depicted in this document, in order to supply the physicians taking care of these patients with an adapted guide to the intensive care setting. Some of its applications since ICU admission include verification of the correct position of the endotracheal tube, contribution to safe cannulation of lines, and identification of complications and thrombotic events. Furthermore, pleural and lung ultrasound can be an alternative diagnostic test to assess the degree of involvement of the lung parenchyma by means of the evaluation of specific ultrasound patterns, identification of pleural effusions and barotrauma. Echocardiography provides information of heart involvement, detects cor pulmonale and shock states.

Narrative review of ultrasound in the management of the critically ill patient with SARS-CoV-2 infection (COVID-19): clinical applications in intensive care medicine

The clinical picture of SARS-CoV-2 infection (COVID-19) is characterized in its more severe form, by an acute respiratory failure which can worsen to pneumonia and acute respiratory distress syndrome (ARDS), and get complicated with thrombotic events and heart dysfunction. Therefore, admission to the Intensive Care Unit (ICU) is common.

Ultrasound, which has become an everyday tool in the ICU, can be very useful during COVID-19 pandemic, since it provides the clinician with information which can be interpreted and integrated within a global assessment during the physical examination. A description of some of the potential applications of ultrasound is depicted in this document, in order to supply the physicians taking care of these patients with a adapted guide to the intensive care setting.

Some of its applications since ICU admission include verification of the correct position of the endotracheal tube, contribution to safe cannulation of lines, and identification of complications and thrombotic events. Furthermore, pleural and lung ultrasound can be an alternative diagnostic test to assess the degree of involvement of the lung parenchyma by means of the evaluation of specific ultrasound patterns, identification of pleural effusions and barotrauma. Echocardiography provides information of heart involvement, detects cor pulmonale and shock states.

Fluctuations of driving pressure during mechanical ventilation indicates elevated central venous pressure and poor outcomes

Inappropriate mechanical ventilation may induce hemodynamic alterations through cardiopulmonary interactions. The aim of this study was to explore the relationship between airway pressure and central venous pressure during the first 72 h of mechanical ventilation and its relevance to patient outcomes. We conducted a retrospective study of the Department of Critical Care Medicine of Peking Union Medical College Hospital and a secondary analysis of the MIMIC-III clinical database. The relationship between the ranges of driving pressure and central venous pressure during the first 72 h and their associations with prognosis were investigated. Data from 2790 patients were analyzed. Wide range of driving airway pressure (odds ratio, 1.0681; 95% CI, 1.0415-1.0953; p < 0.0001) were independently associated with mortality, ventilator-free time, intensive care unit and hospital length of stay. Furthermore, wide range of driving pressure and elevated central venous pressure exhibited a close correlation. The area under receiver operating characteristic demonstrated that range of driving pressure and central venous pressure were measured at 0.689 (95% CI, 0.670-0.707) and 0.681 (95% CI, 0.662-0.699), respectively. Patients with high ranges of driving pressure and elevated central venous pressure had worse outcomes. Post hoc tests showed significant differences in 28-day survival rates (log-rank (Mantel-Cox), 184.7; p < 0.001). In conclusion, during the first 72 h of mechanical ventilation, patients with hypoxia with fluctuating driving airway pressure have elevated central venous pressure and worse outcomes.

Novel insights on the pulmonary vascular consequences of COVID-19

In the last few months, the number of cases of a new coronavirus-related disease (COVID-19) rose exponentially, reaching the status of a pandemic. Interestingly, early imaging studies documented that pulmonary vascular thickening was specifically associated with COVID-19 pneumonia, implying a potential tropism of the virus for the pulmonary vasculature. Moreover, SARS-CoV-2 infection is associated with inflammation, hypoxia, oxidative stress, mitochondrial dysfunction, DNA damage, and lung coagulopathy promoting endothelial dysfunction and microthrombosis. These features are strikingly similar to what is seen in pulmonary vascular diseases. Although the consequences of COVID-19 on the pulmonary circulation remain to be explored, several viruses have been previously thought to be involved in the development of pulmonary vascular diseases. Patients with preexisting pulmonary vascular diseases also appear at increased risk of morbidity and mortality. The present article reviews the molecular factors shared by coronavirus infection and pulmonary vasculature defects, and the clinical relevance of pulmonary vascular alterations in the context of COVID-19.

Potential drug-drug interactions associated with drugs currently proposed for COVID-19 treatment in patients receiving other treatments

Patients with COVID-19 are sometimes already being treated for one or more other chronic conditions, especially if they are elderly. Introducing a treatment against COVID-19, either on an outpatient basis or during hospitalization for more severe cases, raises the question of potential drug-drug interactions. Here, we analyzed the potential or proven risk of the co-administration of drugs used for the most common chronic diseases and those currently offered as treatment or undergoing therapeutic trials for COVID-19. Practical recommendations are offered, where possible.

Pulmonary and systemic hemodynamics are associated with myocardial injury in the acute respiratory distress syndrome

Background

Whether right and left heart hemodynamics are associated with myocardial injury in the acute respiratory distress syndrome (ARDS) is not known.

Methods

We performed a retrospective cohort study of subjects who had right heart catheterization within the ALVEOLI trial and Fluid and Catheter Treatment Trial. Myocardial injury was assessed using a highly sensitive troponin assay (hsTn; Abbot ARCHITECT). Hemodynamic variables included right atrial pressure, pulmonary artery wedge pressure, cardiac index and stroke volume, pulmonary vascular resistance, pulmonary arterial compliance, and pulmonary effective arterial elastance. We performed linear, logistic, and Cox regression to determine the association of hemodynamic variables with myocardial injury and to determine if hemodynamics mediated the association between myocardial injury and death.

Results

Among 252 ARDS patients, median day 0 troponin was 65.4 (13.8–397.8) ng/L. Lower cardiac index (β −0.23 SE 0.10; P < 0.001) and stroke volume (β −0.26 SE 0.005; P < 0.001), higher pulmonary vascular resistance (β 0.22 SE 0.11; P < 0.001), lower pulmonary arterial compliance (β −0.24 SE 0.06; P < 0.001), and higher arterial elastance (β 0.27 SE 0.43; P < 0.001) were associated with greater myocardial injury in univariable and adjusted models. Changes in stroke volume, cardiac index, pulmonary arterial compliance, pulmonary vascular resistance, and arterial elastance were all associated with progressive myocardial injury over three days. hsTn levels were associated with mortality; however, the association was attenuated after adjustment for each of stroke volume, pulmonary vascular resistance, pulmonary arterial compliance, and arterial elastance.

Conclusion

Pulmonary vascular hemodynamics are associated with myocardial injury in ARDS, while filling pressures are not. Pulmonary vascular disease may represent a treatable contributor to myocardial injury in ARDS.

Indications for and Findings on Transthoracic Echocardiography in COVID-19

Background

Despite growing evidence of cardiovascular complications associated with coronavirus disease 2019 (COVID-19), there are few data regarding the performance of transthoracic echocardiography (TTE) and the spectrum of echocardiographic findings in this disease.

Methods

A retrospective analysis was performed among adult patients admitted to a quaternary care center in New York City between March 1 and April 3, 2020. Patients were included if they underwent TTE during the hospitalization after a known positive diagnosis for COVID-19. Demographic and clinical data were obtained using chart abstraction from the electronic medical record.

Results

Of 749 patients, 72 (9.6%) underwent TTE following positive results on severe acute respiratory syndrome coronavirus-2 polymerase chain reaction testing. The most common clinical indications for TTE were concern for a major acute cardiovascular event (45.8%) and hemodynamic instability (29.2%). Although most patients had preserved biventricular function, 34.7% were found to have left ventricular ejection fractions ≤ 50%, and 13.9% had at least moderately reduced right ventricular function. Four patients had wall motion abnormalities suggestive of stress-induced cardiomyopathy. Using Spearman rank correlation, there was an inverse relationship between high-sensitivity troponin T and left ventricular ejection fraction (ρ = −0.34, P = .006). Among 20 patients with prior echocardiograms, only two (10%) had new reductions in LVEF of >10%. Clinical management was changed in eight individuals (24.2%) in whom TTE was ordered for concern for acute major cardiovascular events and three (14.3%) in whom TTE was ordered for hemodynamic evaluation.

Conclusions

This study describes the clinical indications for use and diagnostic performance of TTE, as well as findings seen on TTE, in hospitalized patients with COVID-19. In appropriately selected patients, TTE can be an invaluable tool for guiding COVID-19 clinical management.

Roles of apoptosis and inflammation in a rat model of acute lung injury induced right ventricular dysfunction

AIM

The effect of intratracheal lipopolysaccharide (LPS) instillation on right ventricular dysfunction in rats was studied with the aim of exploring underlying mechanisms.

MAIN METHODS

A single dose of LPS (10 mg/kg) or an equal volume of saline was instilled intratracheally and lung injury evaluated using histopathologic scoring and wet/dry (W/D) weight ratio at 6 or 12 h post-administration. Besides, serum atrial natriuretic peptide (ANP) was detected using an enzyme-linked immunosorbent assay (ELISA) and right ventricle β-myosin heavy chain (β-MHC) presence was examined using reverse transcription polymerase chain reaction (RT-PCR). Echocardiography examined pulmonary artery acceleration time (PAAT), right ventricular free wall thickness (RVFWT), tricuspid annular plane systolic excursion (TAPSE), and right ventricular end-diastolic diameter (RVEDD). In addition, right ventricular TUNEL staining and Western blots of Bax and Bcl-2 were performed. Right ventricle and left ventricle caspases-3, -8, and -9 activity were examined using fluorometric assay. Finally, right ventricle myeloperoxidase (MPO) neutrophil staining, and right ventricle and plasma cytokines TNF-α, IL-1β, IL-6 detection was performed.

KEY FINDINGS

Histopathologic lung injury and increased W/D weight ratio was seen at 6 h after LPS intratracheal instillation, along with increased ANP, but not β-MHC. Pulmonary hypertension was indicated by decreased PAAT at 6 h post-exposure. Right ventricular systolic dysfunction and dilation were observed at 12 h post-exposure, as indicated by a significant decrease of TAPSE and increase of RVEDD. Of note, the procedure led to an increased right ventricle TUNEL positive cardiomyocytes, an increased Bax/Bcl-2 ratio, and increased right and left ventricle caspases-3, -8, and -9 activity as early as 6 h post-exposure, which was paralleled by increased right ventricle MPO staining and increased expression of right ventricle and serum cytokines TNF-α, IL-1β, and IL-6.

SIGNIFICANCE

As well as acute lung injury, a single dose of LPS intratracheally instilled can induce pulmonary hypertension at 6 h post-exposure, with obvious right ventricular systolic dysfunction and right ventricular dilation present at 12 h post-exposure, possibly via cardiomyocytes apoptosis and inflammation.

Assessment of the effects of inspiratory load on right ventricular function

PURPOSE OF REVIEW

The right ventricle (RV) plays a pivotal role during respiratory failure because of its high sensitivity to small loading changes during inspiration. Both RVs, preload and afterload, are altered during inspiration, either in spontaneous breathing or during mechanical ventilation. Some clinical situations especially affect RV load during inspiration, for example acute asthma and acute respiratory distress syndrome. The aim of this review is to explain and to summarize the different mechanisms leading to RV failure in these situations.

RECENT FINDINGS

Research has recently reemphasized the importance to well known physiology of the venous return which is a contributor of RV preload. Authors recently focused on the mean systemic filling pressure which is one of the determinants of venous return. Venous return may change in opposite direction according to the type of ventilation (spontaneous or assisted). Recent works have also demonstrated the crucial impact of lung inflation and driving pressure on RV afterload, and have confirmed the deleterious effect of severe RV failure, described as acute cor pulmonale. In most situations of RV overload induced by inspiration, significant pulse pressure variations are observed, either called 'pulsus paradoxus' in spontaneously breathing patients or 'reverse pulsus paradoxus' in mechanically ventilated patients.

SUMMARY

RV is very sensitive to abnormal inspiration, which is always responsible for an increase in its afterload. Pulse pressure variations, central venous pressure and especially echocardiography may monitor RV function in abnormal clinical situations. The pulmonary artery catheter was also proposed although now less used.

Right ventricular dysfunction during acute respiratory distress syndrome and veno-venous extracorporeal membrane oxygenation

Severe ARDS can be complicated by right ventricular (RV) failure. The etiology of RV failure in ARDS is multifactorial. Vascular alterations, hypoxia, hypercapnia and effects of mechanical ventilation may play a role. Echocardiography has an important role in diagnosing RV failure in ARDS patients. Once extracorporeal membrane oxygenation (ECMO) is indicated in these patients, the right ECMO modus needs to be chosen. In this review, the etiology, diagnosis and management of RV failure in ARDS will be briefly outlined. The beneficial effect of veno-venous (VV) ECMO on RV function in these patients will be illustrated. Based on this, we will give recommendations regarding choice of ECMO modus and provide an algorithm for management of RV failure in VV ECMO supported patients.

Right heart function during acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is burdened with significant mortality, mainly in connection with circulatory failure. The right ventricle (RV) is the weak link of hemodynamic stability among ARDS patients and its failure, also named "severe" acute cor pulmonale (ACP), is responsible for excess mortality. Driving pressure ≥18 cmH₂O, PaCO₂ ≥48 mmHg and PaO₂/FiO₂ <150 mmHg are three preventable factors recently identified as independently associated with ACP, on which ventilator strategy designed to protect the RV has to focus. This is largely achieved by the use of early and extended sessions of prone positioning (PP) and by daily monitoring of the RV by echocardiography.

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

OBJECTIVES

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

DESIGN, SETTING, PATIENTS

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

MAIN RESULTS

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

CONCLUSIONS

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

The Right Ventricle in ARDS

ARDS is associated with poor clinical outcomes, with a pooled mortality rate of approximately 40% despite best standards of care. Current therapeutic strategies are based on improving oxygenation and pulmonary compliance while minimizing ventilator-induced lung injury. It has been demonstrated that relative hypoxemia can be well tolerated, and improvements in oxygenation do not necessarily translate into survival benefit. Cardiac failure, in particular right ventricular dysfunction (RVD), is commonly encountered in moderate to severe ARDS and is reported to be one of the major determinants of mortality. The prevalence rate of echocardiographically evident RVD in ARDS varies across studies, ranging from 22% to 50%. Although there is no definitive causal relationship between RVD and mortality, severe RVD is associated with increased mortality. Factors that can adversely affect RV function include hypoxic pulmonary vasoconstriction, hypercapnia, and invasive ventilation with high driving pressure. It might be expected that early diagnosis of RVD would be of benefit; however, echocardiographic markers (qualitative and quantitative) used to prospectively evaluate the right ventricle in ARDS have not been tested in adequately powered studies. In this review, we examine the prognostic implications and pathophysiology of RVD in ARDS and discuss available diagnostic modalities and treatment options. We aim to identify gaps in knowledge and directions for future research that could potentially improve clinical outcomes in this patient population.

Blockade of CXC chemokine receptor 3 on endothelial cells protects against sepsis-induced acute lung injury

BACKGROUND

CXCR3, a G-protein coupled chemokine receptor, has been shown to play a critical role in recruiting inflammatory cells into lungs in several studies. However, its roles in polymicrobial septic acute lung injury (ALI) is yet unknown. Therefore, the purpose of this study was to elucidate the protective effects of CXCR3 blockade on pulmonary microvascular endothelial cells (PMVECs) in septic ALI and explore potential mechanisms.

MATERIALS AND METHODS

ALI was induced by polymicrobial sepsis through cecal ligation and puncture surgery. The expression of CXCR3 on pulmonary microvascular endothelial cells was measured 24 h after cecal ligation and puncture surgery. In addition, the protective effects of neutralizing antibody were detected, including protein concentration, inflammation cell counts, lung ​wet-to-dry ratio, and lung damages. In human umbilical vein endothelial cells (HUVECs) culture condition, CXCR3 expression was measured after exposure to tumor necrosis factor-α. The permeability and apoptosis ratio were detected through CXCR3 gene silencing on HUVECs. The p38 mitogen-activated protein kinase (MAPK) was analyzed with Western blot.

RESULTS

CXCR3 expression was upregulated both in vivo and in vitro. After CXCR3 neutralizing antibody administrated intraperitoneally, the protein concentration, inflammatory cell counts in BALF and lung ​wet-to-dry ratio were decreased significantly, as well as the lung tissue damages. In vitro, CXCR3 gene silencing inhibited tumor necrosis factor-α and CXCL10-induced hyperpermeability and apoptosis in HUVECs. In addition, p38 mitogen-activated protein kinase activation was essential for CXCR3-mediated apoptosis.

CONCLUSIONS

CXCR3 blockade exerts protective effects on ALI at least partly by inhibiting endothelial cells apoptosis and decreasing the leakage of protein-rich fluid and inflammatory cells. Blockade of CXCR3 may be a promising therapeutic strategy for severe sepsis-induced ALI.

Recent advances in understanding and treating ARDS

Acute respiratory distress syndrome represents a complex syndrome with considerable morbidity and mortality, for which there exist no targeted treatment strategies. However, recent advances in clinical care have improved outcomes, and we will review a number of these approaches here, as well as explore the mechanisms underlying the benefit of intervention that might point us in the direction toward future treatment and preventive strategies for this devastating syndrome.