The potential role and limitations of echocardiography in acute respiratory distress syndrome

Echocardiographic Findings in Critically Ill COVID-19 Patients Treated With and Without Extracorporeal Membrane Oxygenation

OBJECTIVES

To describe echocardiographic findings among mechanically ventilated patients with COVID-19 acute respiratory distress syndrome, comparing those with and without venovenous extracorporeal membrane oxygenation (VV ECMO) support.

DESIGN

Single-center, retrospective cohort study.

SETTING

Intensive care unit (ICU) of a quaternary academic center.

PARTICIPANTS

Patients with COVID-19 admitted between March 2020 and June 2021 receiving mechanical ventilation, with an echocardiogram within 72 hours of admission.

INTERVENTIONS

Admission and follow-up echocardiograms during ICU stay.

MEASUREMENTS

Patient characteristics and echocardiographic findings were analyzed. Mortality odds ratio (OR) for right ventricular (RV) systolic dysfunction and acute cor pulmonale (ACP) was calculated.

MAIN RESULTS

Among 242 patients, 145 (60%) received VV ECMO. Median (IQR) PaO2/FiO2 was 76 (65-95) and 98 (85-140) in ECMO and non-ECMO patients, respectively (p ≤ 0.001). Initial echocardiograms showed no significant differences in left ventricular systolic dysfunction (10% v 15 %, p = 0.31) and RV systolic dysfunction (38% v. 27%, p = 0.27) between ECMO and non-ECMO patients. ACP was more frequent in the ECMO group at baseline (41% v. 26 %, p = 0.02). During the ICU stay, patients on ECMO exhibited a higher prevalence of RV systolic dysfunction (55% v 34%, p = 0.001) and ACP (51% v 26%, p = 0.002). RV systolic dysfunction (OR 1.99; 95% CI 1.09-3.63) and ACP (OR 2.95; 95% CI 1.55-5.62) on the follow-up echocardiograms were associated with higher odds of ICU mortality.

CONCLUSIONS

The prevalence of echocardiographic abnormalities, in particular RV dysfunction, was frequent among patients with COVID-19 receiving VV ECMO support and was associated with worse clinical outcomes.

Echocardiographic and Point-of-Care Ultrasonography (POCUS) Guidance in the Management of the ECMO Patient

Veno-arterial (V-A) and Veno-venous (V-V) extracorporeal membrane oxygenation (ECMO) support is increasingly utilized for acute cardiogenic shock and/or respiratory failure. Echocardiography and point-of-care ultrasonography (POCUS) play a critical role in the selection and management of these critically ill patients, however, there are limited guidelines regarding their application. This comprehensive review describes current and potential application of echocardiography and POCUS for pre-ECMO assessment and patient selection, cannulation guidance with emphasis on dual-lumen configurations, diagnosis of ECMO complications and trouble-shooting of cannula malposition, diagnosis of common cardiac or pulmonary pathologies, and assessment of ECMO weaning appropriateness including identification of the aortic mixing point in V-A ECMO.

Ultrasonography in the intensive care unit: a bibliometrics analysis

Background

Ultrasonography is widely used in critical care practice. The status of related studies remains unclear. The purpose of this study is to analyze current literature investigating the use of ultrasound in critical care units by using bibliometric analysis.

Methods

The Science Citation Index Expanded (SCI-E) database was used for data retrieval. The search formula for literature retrieval was "ultrasound" OR "ultrasonography" AND "intensive care unit" OR "critical care unit" OR "intensive care" OR "critical care". The bibliometric software package of R software was used to analyze the results. Information of related literatures were analyzed.

Results

Finally, 3,715 articles were included. The number of published articles and the number of references increased annually. The research fields included medical imaging, critical care medicine, cardiology, etc. The United States has published more documents in this field than other countries and has shown the highest rate of cooperation with other countries. Among the top 10 research institutions with the largest number of publications, 5 are from France and 3 are from the United States. There are many authors from China in the top 10 published studies. Among the top 10 journals with the largest number of published articles, 5 journals are top journals in the field of critical care medicine. Among the top 10 keywords, there are 5 of ultrasound specialty and 2 of critical care medicine.

Conclusions

Researches on the use of ultrasound in critical care units are mainly concentrated in several developed countries in Europe and the United States. Chinese research institutions should perform more studies in this field and increase cooperation with institutions from other countries.

Point-of-Care Echocardiography in the Difficult-to-Image Patient in the ICU: A Narrative Review

OBJECTIVES

The objective of this narrative review was to address common obstacles encountered in the ICU to acquiring quality and interpretable images using point-of-care echocardiography.

DATA SOURCES

Detailed searches were performed using PubMed and Ovid Medline using medical subject headings and keywords on topics related to patient positioning, IV echo contrast, alternative subcostal views, right ventricular outflow tract (RVOT) hemodynamics, and point-of-care transesophageal echocardiography. Articles known to the authors were also selected based on expert opinion.

STUDY SELECTION

Articles specific to patient positioning, IV echo contrast, alternative subcostal views, RVOT hemodynamics, and point-of-care transesophageal echocardiography were considered.

DATA EXTRACTION

One author screened titles and extracted relevant data while two separate authors independently reviewed selected articles.

DATA SYNTHESIS

Impediments to acquiring quality and interpretable images in critically ill patients are common. Notably, body habitus, intra-abdominal hypertension, dressings or drainage tubes, postoperative sternotomies, invasive mechanical ventilation, and the presence of subcutaneous emphysema or lung hyperinflation are commonly encountered obstacles in transthoracic image acquisition in the ICU. Despite these obstacles, the bedside clinician may use obstacle-specific maneuvers to enhance image acquisition. These may include altering patient positioning, respiratory cycle timing, expanding the subcostal window to include multilevel short-axis views for use in the assessment of RV systolic function and hemodynamics, coronal transhepatic view of the inferior vena cava, and finally point-of-care transesophageal echocardiography.

CONCLUSIONS

Despite common obstacles to point-of-care echocardiography in critically ill patients, the beside sonographer may take an obstacle-specific stepwise approach to enhance image acquisition in difficult-to-image patients.

Echocardiographic parameters in COVID-19 patients and their association with ICU mortality: a prospective multicenter observational study

BACKGROUND

Echocardiography has become an integral part of the management of critically ill patients. It helps to diagnose and treat various conditions. COVID-19 patients can develop cardiac dysfunction. We planned to study the echocardiographic parameters in COVID-19 patients.

METHODS

We conducted a prospective observational multicenter study after institutional ethical committee approval. COVID-19 pneumonia patients admitted to the intensive care unit (ICU) were enrolled. The echocardiographic evaluation was done within 24-48 hours of admission. Assessment of the left and right heart with systolic and left ventricular diastolic function evaluation was done. The primary outcome was ICU mortality. The secondary outcomes were the length of ICU stay and duration of mechanical ventilation.

RESULTS

Among 573 patients mean age was 57.17 (14.67) with 68.60% being males. On day 1 of ICU, invasive mechanical ventilation was used in 257 (45%) patients. One hundred and forty-eight (25.83%) patients were on vasopressors when echocardiography was performed. Severe left ventricle (LV) systolic dysfunction was seen in 8.7% of patients and had higher odds of mortality [2.48(1.058-5.807), p = 0.037] followed by E and e' with odds ratio of [0.984(0.971-0.998), p = 0.021] and 0.897 (0.805-0.998), p = 0.046], respectively. E/e' indicative of filling pressure of the LV was not found to be significant. Troponin I, E/A, and RV dilatation were similar among survivors and non-survivors.

CONCLUSION

Echocardiographic evaluation in COVID-19 patients showed severe LV systolic dysfunction was associated with ICU mortality. E/e' was not found to be significant but lower e' was associated with higher mortality. Trial registration IEC 131/2020, CTRI/2020/06/025858 date 13th June 2020.

CORONA (COre ultRasOund of covid in iNtensive care and Acute medicine) study: National service evaluation of lung and heart ultrasound in intensive care patients with suspected or proven COVID-19

BACKGROUND

Combined Lung Ultrasound (LUS) and Focused UltraSound for Intensive Care heart (FUSIC Heart - formerly Focused Intensive Care Echocardiography, FICE) can aid diagnosis, risk stratification and management in COVID-19. However, data on its application and results are limited to small studies in varying countries and hospitals. This United Kingdom (UK) national service evaluation study assessed how combined LUS and FUSIC Heart were used in COVID-19 Intensive Care Unit (ICU) patients during the first wave of the pandemic.

METHOD

Twelve trusts across the UK registered for this prospective study. LUS and FUSIC Heart data were obtained, using a standardised data set including scoring of abnormalities, between 1st February 2020 to 30th July 2020. The scans were performed by intensivists with FUSIC Lung and Heart competency as a minimum standard. Data was anonymised locally prior to transfer to a central database.

RESULTS

372 studies were performed on 265 patients. There was a small but significant relationship between LUS score >8 and 30-day mortality (OR 1.8). Progression of score was associated with an increase in 30-day mortality (OR 1.2). 30-day mortality was increased in patients with right ventricular (RV) dysfunction (49.4% vs 29.2%). Severity of LUS score correlated with RV dysfunction (p < 0.05). Change in management occurred in 65% of patients following a combined scan.

CONCLUSIONS

In COVID-19 patients, there is an association between lung ultrasound score severity, RV dysfunction and mortality identifiable by combined LUS and FUSIC Heart. The use of 12-point LUS scanning resulted in similar risk score to 6-point imaging in the majority of cases. Our findings suggest that serial combined LUS and FUSIC Heart on COVID-19 ICU patients may aid in clinical decision making and prognostication.

Right ventricular free wall longitudinal strain is independently associated with mortality in mechanically ventilated patients with COVID-19

BACKGROUND

Right ventricular (RV) dysfunction has been commonly reported in patients with Coronavirus disease 2019 (COVID-19), and is associated with mortality in mixed cohorts of patients requiring and not requiring invasive mechanical ventilation (IMV). Using RV-speckle tracking echocardiography (STE) strain analysis, we aimed to identify the prevalence of RV dysfunction (diagnosed by abnormal RV-STE) in patients with COVID-19 that are exclusively undergoing IMV, and assess association between RV dysfunction and 30 day mortality. We performed a prospective multicentre study across 10 ICUs in Scotland from 2/9/20 to 22/3/21. One-hundred-and-four echocardiography scans were obtained from adult patients at a single timepoint between 48 h after intubation, and day 14 of intensive care unit admission. We analysed RV-STE using RV free-wall longitudinal strain (RVFWLS), with an abnormal cutoff of  > -20%. We performed survival analysis using Kaplan-Meier, log rank, and multivariate cox-regression (prespecified covariates were age, gender, ethnicity, severity of illness, and time since intubation).

RESULTS

Ninety-four/one-hundred-and-four (90.4%) scans had images adequate for RVFWLS. Mean RVFWLS was -23.0% (5.2), 27/94 (28.7%) of patients had abnormal RVFWLS. Univariate analysis with Kaplan-Meier plot and log-rank demonstrated that patients with abnormal RVFWLS have a significant association with 30-day mortality (p = 0.047). Multivariate cox-regression demonstrated that abnormal RVFWLS is independently associated with 30-day mortality (Hazard-Ratio 2.22 [1.14-4.39], p = 0.020).

CONCLUSIONS

Abnormal RVFWLS (> -20%) is independently associated with 30-day mortality in patients with COVID-19 undergoing IMV. Strategies to prevent RV dysfunction, and treatment when identified by RVFWLS, may be of therapeutic benefit to these patients.

TRIAL REGISTRATION

Retrospectively registered 21st Feb 2021.

CLINICALTRIALS

gov Identifier: NCT04764032.

Approach to echocardiography in ARDS patients in the prone position: A systematic review

Echocardiography is commonly utilized in patients with acute respiratory distress syndrome (ARDS) for assessment of cardiac function, volume status, and the potential development of acute cor pulmonale. In severe ARDS, prone positioning is frequently used, which imposes technical challenges during transthoracic echocardiography (TTE) image acquisition. Moreover, prone positioning can affect cardiopulmonary function in ways that are reflected on the echocardiographic findings in this position. Historically, a transesophageal approach was recommended when a patient is prone, with few studies reporting utility of TTE in this setting. However, recent publications have begun to address this knowledge gap. This review explores recent literature addressing the use of TTE in prone patients with ARDS, with a special focus on the cardiopulmonary effects of proning and potential solutions to the technical difficulties that arise in this position.

Value of early critical care transthoracic echocardiography for patients undergoing mechanical ventilation: a retrospective study

OBJECTIVES

To evaluate whether early intensive care transthoracic echocardiography (TTE) can improve the prognosis of patients with mechanical ventilation (MV).

DESIGN

A retrospective cohort study.

SETTING

Patients undergoing MV for more than 48 hours, based on the Medical Information Mart for Intensive Care III (MIMIC-III) database and the eICU Collaborative Research Database (eICU-CRD), were selected.

PARTICIPANTS

2931 and 6236 patients were recruited from the MIMIC-III database and the eICU database, respectively.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcome was in-hospital mortality. Secondary outcomes were 30-day mortality from the date of ICU admission, days free of MV and vasopressors 30 days after ICU admission, use of vasoactive drugs, total intravenous fluid and ventilator settings during the first day of MV.

RESULTS

We used propensity score matching to analyse the association between early TTE and in-hospital mortality and sensitivity analysis, including the inverse probability weighting model and covariate balancing propensity score model, to ensure the robustness of our findings. The adjusted OR showed a favourable effect between the early TTE group and in-hospital mortality (MIMIC: OR 0.78; 95% CI 0.65 to 0.94, p=0.01; eICU-CRD: OR 0.76; 95% CI 0.67 to 0.86, p<0.01). Early TTE was also associated with 30-day mortality in the MIMIC database (OR 0.71, 95% CI 0.57 to 0.88, p=0.001). Furthermore, those who had early TTE had both more ventilation-free days (only in eICU-CRD: 23.48 vs 24.57, p<0.01) and more vasopressor-free days (MIMIC: 18.22 vs 20.64, p=0.005; eICU-CRD: 27.37 vs 28.59, p<0.001) than the control group (TTE applied outside of the early TTE and no TTE at all).

CONCLUSIONS

Early application of critical care TTE during MV is beneficial for improving in-hospital mortality. Further investigation with prospectively collected data is required to validate this relationship.

Imaging Evaluation of Pulmonary and Non-Ischaemic Cardiovascular Manifestations of COVID-19

Coronavirus Disease 2019 (COVID-19) has been a pandemic challenge for the last year. Cardiovascular disease is the most described comorbidity in COVID-19 patients, and it is related to the disease severity and progression. COVID-19 induces direct damage on cardiovascular system, leading to arrhythmias and myocarditis, and indirect damage due to endothelial dysfunction and systemic inflammation with a high inflammatory burden. Indirect damage leads to myocarditis, coagulation abnormalities and venous thromboembolism, Takotsubo cardiomyopathy, Kawasaki-like disease and multisystem inflammatory syndrome in children. Imaging can support the management, assessment and prognostic evaluation of these patients. Ultrasound is the most reliable and easy to use in emergency setting and in the ICU as a first approach. The focused approach is useful in management of these patients due its ability to obtain quick and focused results. This tool is useful to evaluate cardiovascular disease and its interplay with lungs. However, a detailed echocardiography evaluation is necessary in a complete assessment of cardiovascular involvement. Computerized tomography is highly sensitive, but it might not always be available. Cardiovascular magnetic resonance and nuclear imaging may be helpful to evaluate COVID-19-related myocardial injury, but further studies are needed. This review deals with different modalities of imaging evaluation in the management of cardiovascular non-ischaemic manifestations of COVID-19, comparing their use in emergency and in intensive care.

Transpulmonary thermodilution in patients treated with veno-venous extracorporeal membrane oxygenation

BACKGROUND

We tested the effect of different blood flow levels in the extracorporeal circuit on the measurements of cardiac stroke volume (SV), global end-diastolic volume index (GEDVI) and extravascular lung water index derived from transpulmonary thermodilution (TPTD) in 20 patients with severe acute respiratory distress syndrome (ARDS) treated with veno-venous extracorporeal membrane oxygenation (ECMO).

METHODS

Comparative SV measurements with transesophageal echocardiography and TPTD were performed at least 5 times during the treatment of the patients. The data were interpreted with a Bland-Altman analysis corrected for repeated measurements. The interchangeability between both measurement modalities was calculated and the effects of extracorporeal blood flow on SV measurements with TPTD was analysed with a linear mixed effect model. GEDVI and EVLWI measurements were performed immediately before the termination of the ECMO therapy at a blood flow of 6 l/min, 4 l/min and 2 l/min and after the disconnection of the circuit in 7 patients.

RESULTS

170 pairs of comparative SV measurements were analysed. Average difference between the two modalities (bias) was 0.28 ml with an upper level of agreement of 40 ml and a lower level of agreement of -39 ml within a 95% confidence interval and an overall interchangeability rate between TPTD and Echo of 64%. ECMO blood flow did not influence the mean bias between Echo and TPTD (0.03 ml per l/min of ECMO blood flow; p = 0.992; CI - 6.74 to 6.81). GEDVI measurement was not significantly influenced by the blood flow in the ECMO circuit, whereas EVLWI differed at a blood flow of 6 l/min compared to no ECMO flow (25.9 ± 10.1 vs. 11.0 ± 4.2 ml/kg, p = 0.0035).

CONCLUSIONS

Irrespectively of an established ECMO therapy, comparative SV measurements with Echo and TPTD are not interchangeable. Such caveats also apply to the interpretation of EVLWI, especially with a high blood flow in the extracorporeal circulation. In such situations, the clinician should rely on other methods of evaluation of the amount of lung oedema with the haemodynamic situation, vasopressor support and cumulative fluid balance in mind.

TRIAL REGISTRATION

German Clinical Trials Register (DRKS00021050). Registered 03/30/2020 https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00017237.

Echocardiographic assessment of the right ventricle in COVID -related acute respiratory syndrome

In patients with the novel coronavirus (COVID-19) infection, the echocardiographic assessment of the right ventricle (RV) represents a pivotal element in the understanding of current disease status and in monitoring disease progression. The present manuscript is aimed at specifically describing the echocardiographic assessment of the right ventricle, mainly focusing on the most useful parameters and the time of examination. The RV direct involvement happens quite often due to preferential lung tropism of COVID-19 infection, which is responsible for an interstitial pneumonia characterized also by pulmonary hypoxic vasoconstriction (and thus an RV afterload increase), often evolving in acute respiratory distress syndrome (ARDS). The indirect RV involvement may be due to the systemic inflammatory activation, caused by COVID-19, which may affect the overall cardiovascular system mainly by inducing an increase in troponin values and in the sympathetic tone and altering the volemic status (mainly by affecting renal function). Echocardiographic parameters, specifically focused on RV (dimensions and function) and pulmonary circulation (systolic pulmonary arterial pressures, RV wall thickness), are to be measured in a COVID-19 patient with respiratory failure and ARDS. They have been selected on the basis of their feasibility (that is easy to be measured, even in short time) and usefulness for clinical monitoring. It is advisable to measure the same parameters in the single patient (based also on the availability of valid acoustic windows) which are identified in the first examination and repeated in the following ones, to guarantee a reliable monitoring. Information gained from a clinically-guided echocardiographic assessment holds a clinical utility in the single patients when integrated with biohumoral data (indicating systemic activation), blood gas analysis (reflecting COVID-19-induced lung damage) and data on ongoing therapies (in primis ventilatory settings).

Echocardiography and Multimodality Cardiac Imaging in COVID-19 Patients

The pandemic caused by the new SARS-CoV-2, named coronavirus disease 2019 (COVID-19) disease, has challenged the health-care systems and raised new diagnostic pathways and safety issues for cardiac imagers. Myocardial injury may complicate COVID-19 infection in more than a quarter of patients and due to the wide a range of possible insults, cardiac imaging plays a crucial diagnostic and prognostic role. There is still little evidence regarding the best-imaging pathway and the echocardiographic findings. Most of the data derive from the single centers experiences and case-reports; therefore, our review reflects the recommendations mainly based on expert opinion. Moreover, knowledge is constantly evolving. The health-care system and physicians are called to reorganize the diagnostic pathways to minimize the possibility of spreading the infection. Thus a rapid, bedside, ultrasound assessment of the heart, chest, and leg veins by point-of-care ultrasound seems to be the first-line tool of the fight against the SARS-CoV-2. A second Level of cardiac imaging is appropriate when the result may guide decision-making or may be life-saving. Dedicated scanners should be used and special pathways should be reserved for these patients. The current knowledge on cardiac imaging COVID-19 patients is reviewed.

Transthoracic Echocardiography in Prone Patients With Acute Respiratory Distress Syndrome: A Feasibility Study

Supplemental Digital Content is available in the text.

Objectives:

Patients with acute respiratory distress syndrome are at risk for developing cardiac dysfunction which is independently associated with worse outcomes. Transthoracic echocardiography is an ideal imaging modality for goal-directed assessment and optimization of cardiac function and volume status. Prone positioning, while demonstrated to improve oxygenation, offload the right ventricle, and reduce short-term mortality in acute respiratory distress syndrome, has previously precluded transthoracic echocardiography on these patients. The purpose of this study was to assess the ability to perform focused transthoracic echocardiography examinations on acute respiratory distress syndrome patients in the prone position.

Design:

We performed a cross-sectional study of critically ill patients hospitalized for acute respiratory distress syndrome due to coronavirus disease 2019.

Setting:

This study was conducted in medical and surgical intensive units in a tertiary hospital.

Patients:

We examined 27 mechanically ventilated and prone patients with acute respiratory distress syndrome due to coronavirus disease 2019. Participants were examined at the time of enrollment in an ongoing clinical trial (NCT04306393), and no patients were excluded from echocardiographic analysis.

Interventions:

None.

Measurements and Main Results:

We were able to perform transthoracic echocardiography and obtain satisfactory images for quantitative assessment of right ventricular function in 24 out of 27 (88.9%) and left ventricular function in 26 out of 27 (96.3%) of patients in the prone position, including many who were obese and on high levels of positive end-expiratory pressure (≥ 15 cm H₂O).

Conclusions:

Transthoracic echocardiography can be performed at the prone patient’s bedside by critical care intensivists. These findings encourage the use of focused transthoracic echocardiography for goal-directed cardiac assessment in acute respiratory distress syndrome patients undergoing prone positioning.

miR-495 targets ROCK1 to inhibit lipopolysaccharides-induced WI-38 cells apoptosis and inflammation

Pneumonia is an inflammatory disease with leading mortality rate in children. It has been well established that microRNAs (miRNAs) have been regarded as critical regulator in acute lung injury. We intended to explore the effect and underlying mechanism of miR-495 on lipopolysaccharides (LPS)-induced WI-38 cells. Here, we first found that miR-495 was downregulated in serum of patients with acute stage pneumonia. To establish cell model of acute pneumonia, WI-38 cells were treated with 20 μg/mL LPS, and qRT-PCR analysis also confirmed the downregulation of miR-495 in LPS-induced WI-38 cells. Data from MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) and flow cytometry assays showed that the decreased cell viability and induced cell apoptosis by LPS treatment were also reversed by miR-495 over-expression. Moreover, miR-495 inhibited expression of associated inflammatory factors, which were induced by LPS treatment. Second, ROCK1 (rho-associated, coiled-coil-containing protein kinase 1) was identified as functional target gene of miR-495, whose expression was decreased by miR-495. Mechanically, combination of miR-495 and ROCK1 over-expression reversed the influence of miR-495 on LPS-induced inflammation, viability, and apoptosis. In conclusion, our findings indicated that miR-495 inhibited LPS-induced inflammation injury and apoptosis in WI-38 cells via targeting ROCK1, which would shed light on therapeutic schedule in acute pneumonia.

Severity of acute respiratory distress syndrome and echocardiographic findings in clinical practice-an echocardiographic pilot study

BACKGROUNDS

The still high poor outcome of ARDS may be more consequence of circulatory failure than hypoxemia per se. For patients with circulatory failure and ARDS, hemodynamic instability is directly related to ARDS following pulmonary circulation dysfunction and its consequence - right ventricular (RV) dysfunction.

OBJECTIVES

We hypothesize that in the era of protective ventilation, echocardiographic abnormalities did not parallel ARDS severity, defined by the degree of hypoxemia.

METHODS

We included 63 consecutively identified mechanically ventilated ARDS patients (1st January 2015 to 31th December 2016). All had echocardiography performed routinely within the first 12 h after ICU admission.

RESULTS

The analysis included 110 exams. Twenty-eight patients had severe ARDS (28/63, 44.4%), 27 had moderate ARDS (27/63, 42.1%) and 8 mild ARDS (8/63, 12.7%).There was no difference in echocardiographic findings between mild-moderate and severe ARDS. At Pearson's linear regression analysis, TAPSE was directly correlated with LVEF (r = 0.22, p = 0.021) and inversely with sPAP (r = -0.37, p < 0.001). Systolic pulmonary arterial pressure (sPAP) showed a direct correlation with pCO₂ (r = 0.30, p = 0.002) and an inverse one with pH (r = -0.35, p < 0.001) and TAPSE (r =-0.35, p < 0.001).

CONCLUSIONS

Among patients with ARDS, the severity of disease (as indicated by pO2) does not translate into specific cardiac abnormalities, detected by echocardiography. However, RV function (as indicated by TAPSE) is inversely related to pCO₂ and to sPAP (which therefore may be underestimated in presence ofRV dysfunction). Our data strongly suggest that in mechanically ventilated ARDS, the interpretation of echo findings should consider also pCO₂ values.

Two-dimensional echocardiography after return of spontaneous circulation and its association with in-hospital survival after in-hospital cardiopulmonary resuscitation

This retrospective cohort study investigated the association between in-hospital survival and two-dimensional (2D) echocardiography within 24 hours after the return of spontaneous circulation (ROSC) in patients who underwent in-hospital cardiopulmonary resuscitation (ICPR) after in-hospital cardiopulmonary arrest (IHCA). The 2D-echo and non-2D-echo groups comprised eligible patients who underwent transthoracic 2D echocardiography performed by the cardiology team within 24 hours after ROSC and those who did not, respectively. After propensity score (PS) matching, 142 and 284 patients in the 2D-echo and non-2D-echo groups, respectively, were included. A logistic regression analysis showed that the likelihood of in-hospital survival was 2.35-fold higher in the 2D-echo group than in the non-2D-echo group (P < 0.001). Regarding IHCA aetiology, in-hospital survival after cardiac arrest of a cardiac cause was 2.51-fold more likely in the 2D-echo group than in the non-2D-echo group (P < 0.001), with no significant inter-group difference in survival after cardiac arrest of a non-cardiac cause (P = 0.120). In this study, 2D echocardiography performed within 24 hours after ROSC was associated with better in-hospital survival outcomes for patients who underwent ICPR for IHCA with a cardiac aetiology. Thus, 2D echocardiography may be performed within 24 hours after ROSC in patients experiencing IHCA to enable better treatment.

Right Ventricular Hypertrophy in Refractory Acute Respiratory Distress Syndrome Treated With Venovenous Extracorporeal Membrane Oxygenation Support

OBJECTIVE

In severe acute respiratory distress syndrome (ARDS) treated with extracorporeal membrane oxygenation (ECMO), right ventricular (RV failure) and dilation have been investigated with the use of echocardiography, whereas RV hypertrophy has not been addressed in the literature. The present study assessed the incidence of RV hypertrophy using echocardiography before ECMO treatment and at intensive care unit (ICU) discharge in severe ARDS patients.

DESIGN

Observational, retrospective, single-center study.

SETTING

A single ECMO center.

PARTICIPANTS

The study comprised 46 consecutive patients with severe ARDS.

INTERVENTION

Echocardiographic evaluation and ECMO support.

MEASUREMENTS AND MAIN RESULTS

A dual-lumen cannula was implanted in most patients (38/46 [82.6%]). Before the start of ECMO, RV hypertrophy was present in 28 patients (60.8%) with no significant differences in baseline characteristics between the 2 subgroups. The ICU mortality rate was 30.4% (14/46), with no difference between patients with RV hypertrophy and those without. At ICU discharge, all patients showed RV hypertrophy.

CONCLUSIONS

In severe ARDS treated with ECMO support, RV hypertrophy is a common finding and patients with normal RV wall thickness developed RV hypertrophy after ECMO support. The latter finding may suggest that during ECMO support, the right ventricle still may be subjected to increased afterload. However, additional research should be performed to elucidate the spectrum of mechanism(s) involved in the genesis of RV hypertrophy.

The Role of Echocardiography in Neonates and Pediatric Patients on Extracorporeal Membrane Oxygenation

Indications for extracorporeal membrane oxygenation (ECMO) and extracorporeal cardiopulmonary resuscitation (ECPR) are expanding, and echocardiography is a tool of utmost importance to assess safety, effectiveness and readiness for circuit initiation and separation. Echocardiography is key to anticipating complications and improving outcomes. Understanding the patient's as well as the ECMO circuit's anatomy and physiology is crucial prior to any ECMO echocardiographic evaluation. It is also vital to acknowledge that the utility of echocardiography in ECMO patients is not limited to the evaluation of cardiac function, and that clinical decisions should not be made exclusively upon echocardiographic findings. Though echocardiography has specific indications and applications, it also has limitations, characterized as: prior to and during cannulation, throughout the ECMO run, upon separation and after separation from the circuit. The use of specific and consistent echocardiographic protocols for patients on ECMO is recommended.

Lung imaging: how to get better look inside the lung

In the last years, imaging has played a key role in the diagnosis and monitoring and critical illness, including acute respiratory distress syndrome (ARDS). Chest X-ray (CXR) and computed tomography (CT) are the conventional techniques most performed in the critically ill patients, the latter being the gold standard to assess lung aeration in ARDS patients. In addition, two bedside techniques are now gaining popularity alongside the conventional ones: lung ultrasound (LUS) and electrical impedance tomography (EIT). These techniques do not involve the use of ionizing radiations, are non-invasive and relatively easy to use, and are under extensive investigation as a complement, and for some application a substitution of conventional techniques. At last, positron emission tomography (PET) and magnetic resonance imaging (MRI) can provide functional information on the lung and respiratory function, and are increasingly used in research to improve the understanding of the pathophysiological mechanisms underlying ARDS. The purpose of this review is to give an up-to-date overview of the conventional and emerging imaging techniques available the diagnosis and management of patients with ARDS.

Incidence Proportion of Acute Cor Pulmonale in Patients with Acute Respiratory Distress Syndrome Subjected to Lung Protective Ventilation: A Systematic Review and Meta-analysis

INTRODUCTION

Reported incidence of acute cor pulmonale (ACP) in patients with acute respiratory distress syndrome (ARDS) varies from 10% to 84%, despite being subjected to lung protective ventilation according to the current guidelines. The objective of this review is to find pooled cumulative incidence of ACP in patients with ARDS undergoing lung protective ventilation.

MATERIALS AND METHODS

We searched MEDLINE, EMBASE, Cochrane Library, KoreaMed, LILACS, and WHO Clinical Trial Registry. Cross-sectional or cohort studies were included if they reported or provided data that could be used to calculate the incidence proportion of ACP. Inverse variance heterogeneity (IVhet) and random effect model were used for the main outcome and measures.

RESULTS

We included 16 studies encompassing 1661 patients. The cumulative incidence of ACP using IVhet analysis was 23% (95% confidence interval [CI] = 18%-28%) over 3 days of lung protective ventilation. Random effect analysis of 7 studies (1250 patients) revealed pooled odd ratio of mortality of 1.16 (95% CI = 0.80-1.67, P = 0.44) due to ACP.

CONCLUSION

Patients with ARDS have a 23% risk of developing ACP with lung protective ventilation. Findings of this review indicate the need of updating existing guidelines for ventilating ARDS patients to incorporate right ventricle protective strategy.

Early detection of right ventricular dysfunction using transthoracic echocardiography in ARDS: a more objective approach

PURPOSE

Right ventricular (RV) dysfunction is an independent predictor of morbidity and mortality in acute respiratory distress syndrome (ARDS). Our goal was to describe morphologic changes in the RV using objective measures on transthoracic echocardiography (TTE) that occur following ARDS.

METHODS

We retrospectively measured changes in the following RV parameters from a pre-ARDS TTE to an ARDS TTE: tricuspid annular plane systolic excursion (TAPSE), myocardial performance index (MPI), fractional area change (FAC), systolic pulmonary artery pressure (SPAP), peak tricuspid regurgitant (TR) velocity, and septal shift.

RESULTS

Over 24 months, 14 patients met inclusion/exclusion criteria. Mean TAPSE decreased from 22.4 mm pre-ARDS to 16.3 mm during ARDS, P<.001. Mean MPI increased from 0.19 to 0.38, P=.001. Mean FAC decreased from 60.8% to 41.2%, P=.003. Peak TR velocity increased from 2.67 m/s pre-ARDS to 3.31 m/s during ARDS, P=.02. SPAP and septal shift demonstrated trends but not statistically different between pre-ARDS and ARDS states. TAPSE correlated with ARDS severity (PaO₂ /FiO₂ ratios), P=.004, and was lower among 30-day nonsurvivors compared with survivors, P=.002.

CONCLUSIONS

Mild RV dysfunction is common after ARDS onset. RV morphologic changes coupled with dysfunction can be detected noninvasively through TTE changes with TAPSE, MPI, and FAC. Mild RV dysfunction by TAPSE is associated with ARDS severity and mortality.

Experts' opinion on management of hemodynamics in ARDS patients: focus on the effects of mechanical ventilation

RATIONALE

Acute respiratory distress syndrome (ARDS) is frequently associated with hemodynamic instability which appears as the main factor associated with mortality. Shock is driven by pulmonary hypertension, deleterious effects of mechanical ventilation (MV) on right ventricular (RV) function, and associated-sepsis. Hemodynamic effects of ventilation are due to changes in pleural pressure (Ppl) and changes in transpulmonary pressure (TP). TP affects RV afterload, whereas changes in Ppl affect venous return. Tidal forces and positive end-expiratory pressure (PEEP) increase pulmonary vascular resistance (PVR) in direct proportion to their effects on mean airway pressure (mPaw). The acutely injured lung has a reduced capacity to accommodate flowing blood and increases of blood flow accentuate fluid filtration. The dynamics of vascular pressure may contribute to ventilator-induced injury (VILI). In order to optimize perfusion, improve gas exchange, and minimize VILI risk, monitoring hemodynamics is important.

RESULTS

During passive ventilation pulse pressure variations are a predictor of fluid responsiveness when conditions to ensure its validity are observed, but may also reflect afterload effects of MV. Central venous pressure can be helpful to monitor the response of RV function to treatment. Echocardiography is suitable to visualize the RV and to detect acute cor pulmonale (ACP), which occurs in 20-25 % of cases. Inserting a pulmonary artery catheter may be useful to measure/calculate pulmonary artery pressure, pulmonary and systemic vascular resistance, and cardiac output. These last two indexes may be misleading, however, in cases of West zones 2 or 1 and tricuspid regurgitation associated with RV dilatation. Transpulmonary thermodilution may be useful to evaluate extravascular lung water and the pulmonary vascular permeability index. To ensure adequate intravascular volume is the first goal of hemodynamic support in patients with shock. The benefit and risk balance of fluid expansion has to be carefully evaluated since it may improve systemic perfusion but also may decrease ventilator-free days, increase pulmonary edema, and promote RV failure. ACP can be prevented or treated by applying RV protective MV (low driving pressure, limited hypercapnia, PEEP adapted to lung recruitability) and by prone positioning. In cases of shock that do not respond to intravascular fluid administration, norepinephrine infusion and vasodilators inhalation may improve RV function. Extracorporeal membrane oxygenation (ECMO) has the potential to be the cause of, as well as a remedy for, hemodynamic problems. Continuous thermodilution-based and pulse contour analysis-based cardiac output monitoring are not recommended in patients treated with ECMO, since the results are frequently inaccurate. Extracorporeal CO2 removal, which could have the capability to reduce hypercapnia/acidosis-induced ACP, cannot currently be recommended because of the lack of sufficient data.