Dynamic changes in lung water density and volume following supine body positioning.

PURPOSE: Measure the changes in relative lung water density (rLWD), lung volume, and total lung water content as a function of time after supine body positioning. METHODS: An efficient ultrashort-TE pulse sequence with a yarnball k-space trajectory was used to measure water density-weighted lung images for 25 min following supine body positioning (free breathing, 74-s acquisitions, 3D images at functional residual capacity, 18 time points) in 9 healthy volunteers. Global and regional (10 chest-to-back positions) rLWD, lung volume, and total lung water volume were measured in all subjects at all time points. Volume changes were validated with a nitrogen washout study in 3 participants. RESULTS: Global rLWD increased significantly (p = 0.001) from 31.8 ± 5.5% to 34.8 ± 6.8%, while lung volumes decreased significantly (p < 0.001) from 2390 ± 620 mL to 2130 ± 630 mL over the same 25-min interval. Total lung water volume decreased slightly from 730 ± 125 mL to 706 ± 126 mL (p = 0.028). There was a significant chest-to-back gradient in rLWD (20.7 ± 4.6% to 39.9 ± 6.1%) at all time points with absolute increases of 1.8 ± 1.2% at the chest and 5.4 ± 1.9% at the back. Nitrogen washout studies yielded a similar reduction in lung volume (12.5 ± 0.9%) and time course following supine positioning. CONCLUSION: Lung volumes during tidal breathing decrease significantly over tens of minutes following supine body positioning, with corresponding increases in lung water density (9.2 ± 4.4% relative increase). The total volume of lung water is slightly reduced over this interval (3.3 ± 4.0% relative change). Evaluation of rLWD should take time after supine positioning, and more generally, all sources of lung volume changes should be taken into consideration to avoid significant bias.

Lung ultrasound diagnosis of pulmonary edema resulting from excessive fluid absorption during hysteroscopic myomectomy: a case report.

BACKGROUND: Hysteroscopic surgery is a safe procedure used for diagnosing and treating intrauterine lesions, with a low rate of intraoperative complications. However, it is important to be cautious as fluid overload can still occur when performing any hysteroscopic surgical technique. CASE PRESENTATION: In this case report, we present a unique instance where lung ultrasound was utilized to diagnose pulmonary edema in a patient following a hysteroscopic myomectomy procedure. The development of pulmonary edema was attributed to the excessive absorption of fluid during the surgical intervention. By employing lung ultrasound as a diagnostic tool, we were able to promptly identify and address the pulmonary edema. As a result, the patient received timely treatment with no complications. This case highlights the importance of utilizing advanced imaging techniques, such as lung ultrasound, in the perioperative management of patients undergoing hysteroscopic procedures. CONCLUSIONS: This case report underscores the significance of early detection and intervention in preventing complications associated with fluid overload during hysteroscopic myomectomy procedures.

A Comparative Study of Narrow/Ultra-Wideband Microwave Sensors for the Continuous Monitoring of Vital Signs and Lung Water Level.

This article presents an in-depth investigation of wearable microwave antenna sensors (MASs) used for vital sign detection (VSD) and lung water level (LWL) monitoring. The study looked at two different types of MASs, narrowband (NB) and ultra-wideband (UWB), to decide which one was better. Unlike recent wearable respiratory sensors, these antennas are simple in design, low-profile, and affordable. The narrowband sensor employs an offset-feed microstrip transmission line, which has a bandwidth of 240 MHz at -10 dB reflection coefficient for the textile substrate. The UWB microwave sensor uses a CPW-fed line to excite an unbalanced U-shaped radiator, offering an extended simulated operating bandwidth from 1.5 to 10 GHz with impedance matching ≤-10 dB. Both types of microwave sensors are designed on a flexible RO 3003 substrate and textile conductive fabric attached to a cotton substrate. The specific absorption rate (SAR) of the sensors is measured at different resonant frequencies on 1 g and 10 g of tissue, according to the IEEE C95.3 standard, and both sensors meet the standard limit of 1.6 W/kg and 2 W/kg, respectively. A simple peak-detection algorithm is used to demonstrate high accuracy in the detection of respiration, heartbeat, and lung water content. Based on the experimental results on a child and an adult volunteer, it can be concluded that UWB MASs offer superior performance when compared to NB sensors.

Assessment of Extravascular Lung Water Using Lung Ultrasound in Critically Ill Patients Admitted to Intensive Care Unit.

Background: Lung ultrasound (LUS) is a simple bedside tool to assess overhydration. Our study aimed to assess extravascular lung water (EVLW) using B-lines and correlate it with weaning, duration of mechanical ventilation, and mortality in critically ill patients admitted to the intensive care unit (ICU). Patients and methods: 150 mechanically ventilated ICU patients prospectively observed over 18 months, with their demographic and clinical data noted. Extravascular lung water was monitored using LUS in four intercostal spaces (ICS) from day 1 to day 5, day 7, day 10, and weekly thereafter. Pulmonary fluid burden was graded as low (1-10), moderate (11-20), and high (21-32). Weaning outcome, duration of weaning, mechanical ventilation, ICU stay, and mortality were compared in patients with and without EVLW. Results: Out of 150, 54 patients (36.0%) had EVLW. The mean lung score amongst our patients was 8.57 ± 6.0. The mean time for detection of EVLW was 1.43 ± 2.24 days. Lung score was low in 40 (26.67%) patients, moderate in 9 (6.00%) patients, and high in 5 (3.33%) patients. Incidence of weaning failure (p-value = 0.006), duration of weaning, mechanical ventilation, ICU stay (p-value < 0.0001 each), and overall mortality were significantly higher in patients with EVLW (p-value = 0.006). Conclusion: We conclude that a good proportion of critically ill patients have EVLW. Extravascular lung water significantly increases the duration of weaning, mechanical ventilation days, ICU stay, and overall mortality in critically ill patients. How to cite this article: Rajpal M, Talwar V, Krishna B, Mustafi SM. Assessment of Extravascular Lung Water Using Lung Ultrasound in Critically Ill Patients Admitted to Intensive Care Unit. Indian J Crit Care Med 2024;28(2):165-169.

Dynamic lung water MRI during exercise stress.

PURPOSE: Exercise-induced dyspnea caused by lung water is an early heart failure symptom. Dynamic lung water quantification during exercise is therefore of interest to detect early stage disease. This study developed a time-resolved 3D MRI method to quantify transient lung water dynamics during rest and exercise stress. METHODS: The method was evaluated in 15 healthy subjects and 2 patients with heart failure imaged in transitions between rest and exercise, and in a porcine model of dynamic extravascular lung water accumulation through mitral regurgitation (n = 5). Time-resolved images were acquired at 0.55T using a continuous 3D stack-of-spirals proton density weighted sequence with 3.5 mm isotropic resolution, and derived using a motion corrected sliding-window reconstruction with 90-s temporal resolution in 20-s increments. A supine MRI-compatible pedal ergometer was used for exercise. Global and regional lung water density (LWD) and percent change in LWD (ΔLWD) were automatically quantified. RESULTS: A ΔLWD increase of 3.3 ± 1.5% was achieved in the animals. Healthy subjects developed a ΔLWD of 7.8 ± 5.0% during moderate exercise, peaked at 16 ± 6.8% during vigorous exercise, and remained unchanged over 10 min at rest (-1.4 ± 3.5%, p = 0.18). Regional LWD were higher posteriorly compared the anterior lungs (rest: 33 ± 3.7% vs 20 ± 3.1%, p < 0.0001; peak exercise: 36 ± 5.5% vs 25 ± 4.6%, p < 0.0001). Accumulation rates were slower in patients than healthy subjects (2.0 ± 0.1%/min vs 2.6 ± 0.9%/min, respectively), whereas LWD were similar at rest (28 ± 10% and 28 ± 2.9%) and peak exercise (ΔLWD 17 ± 10% vs 16 ± 6.8%). CONCLUSION: Lung water dynamics can be quantified during exercise using continuous 3D MRI and a sliding-window image reconstruction.

A deep learning model enables accurate prediction and quantification of pulmonary edema from chest X-rays.

BACKGROUND: A quantitative assessment of pulmonary edema is important because the clinical severity can range from mild impairment to life threatening. A quantitative surrogate measure, although invasive, for pulmonary edema is the extravascular lung water index (EVLWI) extracted from the transpulmonary thermodilution (TPTD). Severity of edema from chest X-rays, to date is based on the subjective classification of radiologists. In this work, we use machine learning to quantitatively predict the severity of pulmonary edema from chest radiography. METHODS: We retrospectively included 471 X-rays from 431 patients who underwent chest radiography and TPTD measurement within 24 h at our intensive care unit. The EVLWI extracted from the TPTD was used as a quantitative measure for pulmonary edema. We used a deep learning approach and binned the data into two, three, four and five classes increasing the resolution of the EVLWI prediction from the X-rays. RESULTS: The accuracy, area under the receiver operating characteristic curve (AUROC) and Mathews correlation coefficient (MCC) in the binary classification models (EVLWI < 15, ≥ 15) were 0.93 (accuracy), 0.98 (AUROC) and 0.86(MCC). In the three multiclass models, the accuracy ranged between 0.90 and 0.95, the AUROC between 0.97 and 0.99 and the MCC between 0.86 and 0.92. CONCLUSION: Deep learning can quantify pulmonary edema as measured by EVLWI with high accuracy.

Stress Echo 2030: the new ABCDE protocol defining the future of cardiac imaging.

Functional testing with stress echocardiography is based on the detection of regional wall motion abnormality with two-dimensional echocardiography and is embedded in clinical guidelines. Yet, it under-uses the unique versatility of the technique, ideally suited to describe the different functional abnormalities underlying the same wall motion response during stress. Five parameters converge conceptually and methodologically in the state-of-the-art ABCDE protocol, assessing multiple vulnerabilities of the ischemic patient. The five steps of the ABCDE protocol are (1) step A: regional wall motion; (2) step B: B-lines by lung ultrasound assessing extravascular lung water; (3) step C: left ventricular contractile reserve by volumetric two-dimensional echocardiography; (4) step D: coronary flow velocity reserve in mid-distal left anterior descending coronary with pulsed-wave Doppler; and (5) step E: assessment of heart rate reserve with a one-lead electrocardiogram. ABCDE stress echo offers insight into five functional reserves: epicardial flow (A); diastolic (B), contractile (C), coronary microcirculatory (D), and chronotropic reserve (E). The new format is more comprehensive and allows better functional characterization, risk stratification, and personalized tailoring of therapy. ABCDE protocol is an 'ecumenic' and 'omnivorous' functional test, suitable for all stresses and all patients also beyond coronary artery disease. It fits the need for sustainability of the current era in healthcare, since it requires universally available technology, and is low-cost, radiation-free, and nearly carbon-neutral.

Effects of changes in veno-venous extracorporeal membrane oxygenation blood flow on the measurement of intrathoracic blood volume and extravascular lung water index: a prospective interventional study.

In severe acute respiratory distress syndrome (ARDS), veno-venous extracorporeal membrane oxygenation (V-V ECMO) has been proposed as a therapeutic strategy to possibly reduce mortality. Transpulmonary thermodilution (TPTD) enables monitoring of the extravascular lung water index (EVLWI) and cardiac preload parameters such as intrathoracic blood volume index (ITBVI) in patients with ARDS, but it is not generally recommended during V-V ECMO. We hypothesized that the amount of extracorporeal blood flow (ECBF) influences the calculation of EVLWI and ITBVI due to recirculation of indicator, which affects the measurement of the mean transit time (MTt), the time between injection and passing of half the indicator, as well as downslope time (DSt), the exponential washout of the indicator. EVLWI and ITBVI were measured in 20 patients with severe ARDS managed with V-V ECMO at ECBF rates from 6 to 4 and 2 l/min with TPTD. MTt and DSt significantly decreased when ECBF was reduced, resulting in a decreased EVLWI (26.1 [22.8-33.8] ml/kg at 6 l/min ECBF vs 22.4 [15.3-31.6] ml/kg at 4 l/min ECBF, p < 0.001; and 13.2 [11.8-18.8] ml/kg at 2 l/min ECBF, p < 0.001) and increased ITBVI (840 [753-1062] ml/m2 at 6 l/min ECBF vs 886 [658-979] ml/m2 at 4 l/min ECBF, p < 0.001; and 955 [817-1140] ml/m2 at 2 l/min ECBF, p < 0.001). In patients with severe ARDS managed with V-V ECMO, increasing ECBF alters the thermodilution curve, resulting in unreliable measurements of EVLWI and ITBVI. German Clinical Trials Register (DRKS00021050). Registered 14/08/2018. https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00021050.

Optimizing Fluid Management Guided by Volumetric Parameters in Patients with Sepsis and ARDS.

We compared two de-escalation strategies guided by either extravascular lung water or global end-diastolic volume-oriented algorithms in patients with sepsis and ARDS. Sixty patients with sepsis and ARDS were randomized to receive de-escalation fluid therapy, guided either by the extravascular lung water index (EVLWI, n = 30) or the global end-diastolic volume index (GEDVI, n = 30). In cases of GEDVI > 650 mL/m2 or EVLWI > 10 mL/kg, diuretics and/or controlled ultrafiltration were administered to achieve the cumulative 48-h fluid balance in the range of 0 to -3000 mL. During 48 h of goal-directed de-escalation therapy, we observed a decrease in the SOFA score (p < 0.05). Extravascular lung water decreased only in the EVLWI-oriented group (p < 0.001). In parallel, PaO2/FiO2 increased by 30% in the EVLWI group and by 15% in the GEDVI group (p < 0.05). The patients with direct ARDS demonstrated better responses to dehydration therapy concerning arterial oxygenation and lung fluid balance. In sepsis-induced ARDS, both fluid management strategies, based either on GEDVI or EVLWI, improved arterial oxygenation and attenuated organ dysfunction. The de-escalation therapy was more efficient for direct ARDS.

Update on the Features and Measurements of Experimental Acute Lung Injury in Animals: An Official American Thoracic Society Workshop Report.

Advancements in methods, technology, and our understanding of the pathobiology of lung injury have created the need to update the definition of experimental acute lung injury (ALI). We queried 50 participants with expertise in ALI and acute respiratory distress syndrome using a Delphi method composed of a series of electronic surveys and a virtual workshop. We propose that ALI presents as a "multidimensional entity" characterized by four "domains" that reflect the key pathophysiologic features and underlying biology of human acute respiratory distress syndrome. These domains are 1) histological evidence of tissue injury, 2) alteration of the alveolar-capillary barrier, 3) presence of an inflammatory response, and 4) physiologic dysfunction. For each domain, we present "relevant measurements," defined as those proposed by at least 30% of respondents. We propose that experimental ALI encompasses a continuum of models ranging from those focusing on gaining specific mechanistic insights to those primarily concerned with preclinical testing of novel therapeutics or interventions. We suggest that mechanistic studies may justifiably focus on a single domain of lung injury, but models must document alterations of at least three of the four domains to qualify as "experimental ALI." Finally, we propose that a time criterion defining "acute" in ALI remains relevant, but the actual time may vary based on the specific model and the aspect of injury being modeled. The continuum concept of ALI increases the flexibility and applicability of the definition to multiple models while increasing the likelihood of translating preclinical findings to critically ill patients.

Diagnostic value of transpulmonary thermodilution measurements for acute respiratory distress syndrome in a pig model of septic shock.

BACKGROUND: No direct approach assessing pulmonary vascular permeability exists in the current therapeutic strategy for patients with acute respiratory distress syndrome (ARDS). Transpulmonary thermodilution measures hemodynamic parameters such as pulmonary vascular permeability index and extravascular lung water, enabling clinicians to assess ARDS severity. The aim of this study is to explore a precise transpulmonary thermodilution-based criteria for quantifying the severity of lung injury using a clinically relevant septic-ARDS pig model. METHODS: Thirteen female pigs (weight: 31 ± 2 kg) were intubated, mechanically ventilated under anesthesia, and either assigned to septic shock-induced ARDS or control group. To confirm the development of ARDS, we performed computed tomography (CT) imaging in randomly selected animals. The pulmonary vascular permeability index, extravascular lung water, and other hemodynamic parameters were consecutively measured during the development of septic lung injury. Lung status was categorized as normal (partial pressure of oxygen/fraction of inspired oxygen ≥ 400), or injured at different degrees: pre-ARDS (300-400), mild-to-moderate ARDS (100-300), or severe ARDS (< 100). We also measured serum inflammatory cytokines and high mobility group box 1 levels during the experiment to explore the relationship of the pulmonary vascular permeability index with these inflammatory markers. RESULTS: Using CT image, we verified that animals subjected to ARDS presented an extent of consolidation in bilateral gravitationally dependent gradient that expands over time, with diffuse ground-glass opacification. Further, the post-mortem histopathological analysis for lung tissue identified the key features of diffuse alveolar damage in all animals subjected to ARDS. Both pulmonary vascular permeability index and extravascular lung water increased significantly, according to disease severity. Receiver operating characteristic analysis demonstrated that a cut-off value of 3.9 for the permeability index provided optimal sensitivity and specificity for predicting severe ARDS (area under the curve: 0.99, 95% confidence interval, 0.98-1.00; sensitivity = 100%, and specificity = 92.5%). The pulmonary vascular permeability index was superior in its diagnostic value than extravascular lung water. Furthermore, the pulmonary vascular permeability index was significantly associated with multiple parameters reflecting clinicopathological changes in animals with ARDS. CONCLUSION: The pulmonary vascular permeability index is an effective indicator to measure septic ARDS severity.

Lung Ultrasound to Diagnose Pulmonary Congestion Among Patients on Hemodialysis: Comparison of Full Versus Abbreviated Scanning Protocols.

RATIONALE & OBJECTIVE: Pulmonary congestion contributes to morbidity and mortality in patients with kidney failure on hemodialysis, but physical assessment is an insensitive approach to its detection. Lung ultrasound is useful for assessing the presence and severity of pulmonary congestion, but the most widely validated 28-zone study is cumbersome. We sought to compare abbreviated 4-, 6-, and 8-zone studies to 28-zone studies. STUDY DESIGN: Diagnostic test study. SETTING & PARTICIPANTS: Convenience sample of 98 patients with kidney failure on hemodialysis presenting to an emergency department in the United States. TESTS COMPARED: 4-, 6-, and 8-zone lung ultrasound studies versus a 28-zone lung ultrasound. OUTCOME: Prediction of pulmonary congestion and 30-day mortality. RESULTS: All patients completed a 28-zone lung ultrasound. Correlation coefficients (nonparametric Spearman) between each of the studies were high (all values > 0.84). Bland-Altman analysis showed good agreement. Each of the short-form studies discriminated well with area under the receiver-operator characteristic curve > 0.83 for no-to-mild versus moderate-to-severe pulmonary congestion. During a median follow-up period of 778 days, 46 (47%) died. Patients with moderate-to-severe pulmonary congestion on lung ultrasound had a 30-day mortality rate similar to that observed among patients with no-to-mild pulmonary congestion (OR, 0.95 [95% CI, 0.70-1.29]). LIMITATIONS: Single-center study conducted in an emergency care setting, convenience sample of patients, and lack of long-term follow-up data. CONCLUSIONS: Among hemodialysis patients presenting to an emergency department, 4-, 6-, or 8-zone lung ultrasounds were comparable to 28-zone studies for the assessment of pulmonary congestion. The mortality rates did not differ between those with no-to-mild and moderate-to-severe pulmonary congestion.

Imaging gravity-induced lung water redistribution with automated inline processing at 0.55 T cardiovascular magnetic resonance.

BACKGROUND: Quantitative assessment of dynamic lung water accumulation is of interest to unmask latent heart failure. We develop and validate a free-breathing 3D ultrashort echo time (UTE) sequence with automated inline image processing to image changes in lung water density (LWD) using high-performance 0.55 T cardiovascular magnetic resonance (CMR). METHODS: Quantitative lung water CMR was performed on 15 healthy subjects using free-breathing 3D stack-of-spirals proton density weighted UTE at 0.55 T. Inline image reconstruction and automated image processing was performed using the Gadgetron framework. A gravity-induced redistribution of LWD was provoked by sequentially acquiring images in the supine, prone, and again supine position. Quantitative validation was performed in a phantom array of vials containing mixtures of water and deuterium oxide. RESULTS: The phantom experiment validated the capability of the sequence in quantifying water density (bias ± SD 4.3 ± 4.8%, intraclass correlation coefficient, ICC = 0.97). The average global LWD was comparable between imaging positions (supine 24.7 ± 3.4%, prone 22.7 ± 3.1%, second supine 25.3 ± 3.6%), with small differences between imaging phases (first supine vs prone 2.0%, p < 0.001; first supine vs second supine - 0.6%, p = 0.001; prone vs second supine - 2.7%, p < 0.001). In vivo test-retest repeatability in LWD was excellent (- 0.17 ± 0.91%, ICC = 0.97). A regional LWD redistribution was observed in all subjects when repositioning, with a predominant posterior LWD accumulation when supine, and anterior accumulation when prone (difference in anterior-posterior LWD: supine - 11.6 ± 2.7%, prone 5.5 ± 2.7%, second supine - 11.4 ± 2.9%). Global LWD maps were calculated inline within 23.2 ± 0.3 s following the image reconstruction using the automated pipeline. CONCLUSIONS: Redistribution of LWD due to gravitational forces can be depicted and quantified using a validated free-breathing 3D proton density weighted UTE sequence and inline automated image processing pipeline on a high-performance 0.55 T CMR system.

B-Lines Scores Derived From Lung Ultrasound Provide Accurate Prediction of Extravascular Lung Water Index: An Observational Study in Critically Ill Patients.

INTRODUCTION: Visualization of B-lines via lung ultrasound provides a non-invasive estimation of pulmonary hydration. Extravascular lung water index (EVLWI) and pulmonary vascular permeability index (PVPI) assessed by transpulmonary thermodilution (TPTD) represent the most validated parameters of lung water and alveolocapillary permeability, but measurement is invasive and expensive. This study aimed to compare the correlations of B-lines scores from extensive 28-sector and simplified 4-sector chest scan with EVLWI and PVPI derived from TPTD in the setting of intensive care unit (primary endpoint). METHODS: We performed scoring of 28-sector and 4-sector B-Lines in 50 critically ill patients. TPTD was carried out with the PiCCO-2-device (Pulsion Medical Systems SE, Maquet Getinge Group). Median time exposure for ultrasound procedure was 12 minutes for 28-sector and 4 minutes for 4-sector scan. RESULTS: Primarily, we found close correlations of 28-sector as well as 4-sector B-Lines scores with EVLWI (R2 = 0.895 vs. R2 = 0.880) and PVPI (R2 = 0.760 vs. R2 = 0.742). Both B-lines scores showed high accuracy to identify patients with specific levels of EVLWI and PVPI. The extensive 28-sector B-lines score revealed a moderate advantage compared to simplified 4-sector scan in detecting a normal EVLWI ≤ 7 (28-sector scan: sensitivity = 81.8%, specificity = 94.9%, AUC = 0.939 versus 4-sector scan: sensitivity = 81.8%, specificity = 82.1%, AUC = 0.902). Both protocols were approximately equivalent in prediction of lung edema with EVLWI ≥ 10 (28-sector scan: sensitivity = 88.9%, specificity = 95.7%, AUC = 0.977 versus 4-sector scan: sensitivity = 81.5%, specificity = 91.3%, AUC = 0.958) or severe pulmonary edema with EVLWI ≥ 15 (28-sector scan: sensitivity = 91.7%, specificity = 97.4%, AUC = 0.995 versus 4-sector scan: sensitivity = 91.7%, specificity = 92.1%, AUC = 0.978). As secondary endpoints, our evaluations resulted in significant associations of 28-sector as well as simplified 4-sector B-Lines score with parameters of respiratory function. CONCLUSION: Both B-line protocols provide accurate non-invasive evaluation of lung water in critically ill patients. The 28-sector scan offers a marginal advantage in prediction of pulmonary edema, but needs substantially more time than 4-sector scan.

Utility of Lung Ultrasound in the Estimation of Extravascular Lung Water in a Pediatric Population-A Prospective Observational Study.

OBJECTIVE: Lung ultrasound (LUS) is a promising bedside modality for the estimation of extravascular lung water index (EVLWI), but has not been validated against objective measures in children. This study aimed to investigate the correlation of LUS B-line scoring with EVLWI, thresholds indicating elevated EVLWI, and its outcome following pediatric cardiac surgery. DESIGN: Prospective observational study. SETTING: Cardiothoracic surgical intensive care unit in a tertiary care teaching hospital. PARTICIPANTS: Children younger than 12 years undergoing elective complete surgical correction of cyanotic or acyanotic congenital heart disease (Aristotle score ≤9), excluding neonates, those weighing <3.5 kg, and those with thoracic deformities, pulmonary pathology, and hemodynamic instability. INTERVENTIONS: Extravascular lung water index measurement by transpulmonary thermodilution, along with concurrent LUS B-line and Chest-X ray (CXR) scoring. MEASUREMENTS AND MAIN RESULTS: LUS B-line score had a moderate correlation with EVLWI (Pearson's correlation coefficient 0.57; 95% CI 0.44-0.69). LUS B-line scores showed acceptable discrimination only for higher thresholds of EVLWI (sensitivity 82% and 79%, respectively, for EVLWI >20 mL/kg v sensitivity and specificity 57% and 80% for EVLWI >10 mL/kg). Age, body surface area, vasoactive-inotropic score (VIS), chest X-ray score, and EVLWI but not LUS B-line score were significant predictors for duration of mechanical ventilation in this cohort. CONCLUSIONS: LUS B-line scoring has limited utility in semiquantitative estimation of EVLWI at lower thresholds of EVLWI in pediatric cardiac surgical patients. It may have better discrimination and acceptable sensitivity and specificity at higher thresholds of EVLWI. Contrasting with multiple reports of clinical utility, these results call for wider evaluation of LUS and its clinical modifiers like age, pathology, and pretest probability in estimation of EVLWI.

[Effects on extravascular lung water of lung protective ventilation strategy applied on piglets with acute respiratory distress syndrome induced by paraquat].

Objective: To study the effects on extravascular lung water of lung protective ventilation strategy applying on piglets with acute respiratory distress syndrome (ARDS) induced by paraquat (PQ) under pulse indicating continuous cardiac output (PiCCO) monitoring. Methods: The piglets models with ARDS induced by PQ were established in June 2020 and all of them were received mechanical ventilation and divided into three groups according to tidal volume (V(T)) : small V(T) group (6 ml/kg) , middle V(T) group (10 ml/kg) and large V(T) group (15 ml/kg) , there were 5 piglets in each group. The positive end expiratory pressure (PEEP) were all setup on 10 cmH(2)O. The indexes such as arterial blood gas analysis, oxygenation index (OI) , extravascular lung water index (ELWI) and pulmonary vascular permeability index (PVPI) were monitored at time of before the model was established (baseline) , time of the model was established (t(0)) and 2 h (t(2)) , 4 h (t(4)) , 6 h (t(6)) after mechanical ventilation. Lung tissue were punctured at time of baseline, t(0) and t(6) to be stained by Hematoxylin-eosin (HE) staining and pulmonary pathology were observed under light microscopy. Results: The heart rate (HR) , mean arterial pressure (MAP) and partial pressure of carbon dioxide (PaCO(2)) of all groups were higher than the base value while the pH values, partial pressure of oxygen (PaO(2)) and OI were lower than the base value when the models were established (P<0.05) . After mechanical ventilation, the HR and MAP values of all groups at t(2), t(4) and t(6) were lower than t(0) while the PaCO(2) of t(4) and t(6) were all higher than t(0), the differences were statistically significant (P<0.05) . The PaO(2) and OI of all groups showed a trend of rising at first and then decreasing after mechanical ventilation. The MAP, PaO(2), PaCO(2) and OI of the middle V(T) group and large V(T) group were apparently lower than that of the small V(T) group at t(2), t(4) and t(6) (P<0.05) . The ELWI and PVPI at t(0) of all groups were higher than that of baseline (P<0.05) . The ELWI of the small V(T) group at t(6) were lower than t(0) of the same group and t(6) of the middle V(T) group and large V(T) group (P<0.05) . HE staining showed congestion and edema of alveolar tissue, swelling of capillaries, exudation of red blood cells and widening of alveolar septum in piglets after successful modeling. And further widening of alveolar septum and rupture of alveolar septum could be seen in the lung tissues of each group at t(6), and the injury was the slightest in the small V(T) group. Conclusion: The lung protective ventilation strategy can alleviate the extravascular lung water and ARDS induced by PQ and improve oxygenation.

Effects of exercise on thoracic blood volumes, lung fluid accumulation, and pulmonary diffusing capacity in heart failure with preserved ejection fraction.

Patients with heart failure with preserved ejection fraction (HFpEF) experience symptoms of exertional dyspnea that may be related to lung fluid accumulation during exercise. A computed tomography (CT)-based method was used to measure exercise-induced changes in extravascular lung fluid content and thoracic blood volumes and to determine the effect of lung fluid on lung diffusing capacity for carbon monoxide (DLCO) in stable subjects with HFpEF and healthy controls. Nine subjects with HFpEF (age = 68 ± 8 yr; body mass index = 32.1 ± 2.6 kg/m2) and eight healthy controls (62 ± 9 yr, 23.8 ± 2.4 kg/m2) performed triplicate rebreathe DLCO/DLNO (lung diffusing capacity for nitric oxide) tests in a supine position at rest and duplicate measurements during two 5-min submaximal exercise stages (15W and 35W) and recovery. Subjects subsequently performed a 5-min exercise bout (35W) inside a CT scanner, and extravascular lung fluid content and thoracic blood volumes were quantified at rest and immediately following exercise from thoracic and contrast perfusion scans, respectively. Subjects with HFpEF had a higher lung fluid content at rest compared with controls (means ± SD, HFpEF: 14.4 ± 1.7%, control: 12.8 ± 1.7%, P = 0.043) and a higher lung fluid content following exercise (15.2 ± 2.0% vs. 12.6 ± 1.5%, P = 0.009). Higher lung fluid content was associated with a lower DLCO and alveolar-capillary membrane conductance (Dm) in subjects with HFpEF (DLCO: R = -0.57, P = 0.022, Dm: R = -0.61, P = 0.012) but not in controls. Pulmonary blood volume was not altered by exercise and was similar between groups. Submaximal exercise elicited a greater accumulation of lung fluid in subjects with HFpEF compared with in controls, and lung fluid content was negatively correlated with lung diffusing capacity and alveolar-capillary membrane conductance in subjects with HFpEF.

Assessing Extravascular Lung Water With Ultrasound: A Tool to Individualize Fluid Management?

Aggressive fluid resuscitation has become standard of care for hypotensive patients with sepsis. However, sepsis is a syndrome that occurs in patients with diverse underlying physiology and a one-size-fits-all approach to fluid administration seems misguided. To individualize fluid management, several methods to assess fluid responsiveness have been validated, but even in fluid responsive patients, fluid administration may still be harmful and lead to pulmonary edema. Hence, to individualize fluid management, in addition to fluid responsiveness, fluid tolerance needs to be assessed. This article examines whether lung ultrasound can be useful to detect excess extravascular lung water (EVLW) and thus assess fluid tolerance. The physiology of EVLW and the principles of lung ultrasound are briefly described. Articles examining the correlation between EVLW and lung ultrasound findings in various clinical settings are carefully reviewed. Overall, lung ultrasound has been found to be an excellent tool to detect EVLW, but large outcome studies investigating lung ultrasound-guided fluid management are still lacking.

B-Lines for the assessment of extravascular lung water: Just focused or semi-quantitative?

BACKGROUND: B-lines as typical artefacts of lung ultrasound are considered as surrogate measurement for extravascular lung water. However, B-lines develop in the sub-pleural space and do not allow assessment of the whole lung. Here, we present data from the first observational multi-centre study focusing on the correlation between a B-lines score and extravascular lung water in critically ill patients suffering from a variety of diseases. PATIENTS AND METHODS: In 184 adult patients, 443 measurements were obtained. B-lines were counted and expressed in a score which was compared to extravascular lung water, measured by single-indicator transpulmonary thermodilution. Appropriate correlation coefficients were calculated and receiver operating characteristics (ROC-) curves were plotted. RESULTS: Overall, B-lines score was correlated with body weight-indexed extravascular lung water characterized by r = .59. The subgroup analysis revealed a correlation coefficient in patients without an infection of r = .44, in those with a pulmonary infection of r = .75 and in those with an abdominal infection of r = .23, respectively. Using ROC-analysis the sensitivity and specificity of B-lines for detecting an increased extravascular lung water (>10 mL/kg) was 63% and 79%, respectively. In patients with a P/F ratio <200 mm Hg, sensitivity and specificity to predict an increased extravascular lung water was 71% and 93%, respectively. CONCLUSIONS: Assessment of B-lines does not accurately reflect actual extravascular lung water. In presence of an impaired oxygenation, B-lines may reliably indicate increased extravascular lung water as cause of the oxygenation disorders.

Association of Ang-2, vWF, and EVLWI with risk of mortality in sepsis patients with concomitant ARDS: A retrospective study.

BACKGROUND/PURPOSE: This study aimed to determine the potential effects of angiopoietin-2 (Ang-2), von Willebrand factor (vWF), and extravascular lung water index (EVLWI) on the risk of mortality in sepsis patients with concomitant acute respiratory distress syndrome (ARDS). METHODS: This retrospective study recruited 41 sepsis patients with concomitant ARDS from January 2015 to June 2018. Data of Ang-2 and vWF levels, EVLWI, and sequential organ failure assessment scores were collected at 0, 24, and 48 h after admission to the hospital. RESULTS: The length of intensive care unit stay (P = 0.041) and Acute Physiology and Chronic Health Evaluation-2 (APACHE II) score (P = 0.003) were associated with the risk of mortality. Furthermore, increased Ang-2 levels and EVLWI at 24 h and 48 h were associated with an increased risk of mortality. Moreover, the APACHE II score at hospital admission significantly predicted the risk of mortality (area under the curve [AUC], 0.834; 95% confidence interval [CI], 0.665-0.983). Finally, the models containing a combination of Ang-2 level and EVLWI at 24 h (AUC, 0.908; 95% CI, 0.774-0.996) and Ang-2 level and EVLWI at 48 h (AUC, 0.981; 95% CI, 0.817-1.000) had high diagnostic values for predicting risk of mortality. CONCLUSION: The study findings indicate that Ang-2 levels and EVLWI at 24 h and 48 h after admission are significantly associated with the risk of mortality.