Ultrasound of extravascular lung water: a new standard for pulmonary congestion

Ultrasound in Austere Environments

Ultrasonography is a noninvasive, reliable, repeatable, and inexpensive technology that has dramatically changed the practice of medicine. The clinical use of portable ultrasound devices has grown tremendously over the last 10 years in the fields of intensive care, emergency medicine, and anesthesiology. In this review we present the various ways that handheld portable ultrasound devices can be used in austere environments. The purpose of this review is to consider the wide-ranging applications for providers going into the austere environment, which include pulmonary, ocular, vascular, and trauma evaluations, the postdisaster setting, and the role of ultrasonography in tropical diseases. This review is not meant to be a comprehensive how-to guide for each study type, but an overview of some of the more common wilderness applications. This review also focuses on the limitation of each study type. The goal is to help wilderness medicine providers feel more comfortable incorporating ultrasonography as part of their tool kit when heading into austere environments.

The Added Value of Exercise Stress Echocardiography in Patients With Heart Failure

Doppler echocardiography can provide reliable and repeatable measures of cardiac index (CI), whereas lung ultrasound (LUS) represents a quantitative approach to assess pulmonary congestion. We tested the hypothesis that simultaneous assessment of CI and LUS during exercise stress echocardiography (ESE) may define heart failure (HF) outpatients with different risk of adverse outcome. Standard transthoracic echocardiography and LUS (B-lines) evaluation were assessed during semisupine ESE. CI and B-lines were measured at baseline and peak exercise. Resting plasma B-type natriuretic peptide levels were also evaluated. We enrolled 105 HF patients (87 males; age 62 ± 11 years; New York Heart Association class I to III) with reduced left ventricular ejection fraction (30 ± 7%). Patients were classified into 4 profiles: (1) peak CI ≥4.0 l/min/m² and peak B-lines <15 (no evidence of congestion or hypoperfusion, n = 47); (2) peak CI ≥4.0 l/min/m² and peak B-lines ≥15 (congestion with adequate perfusion, n = 23); (3) peak CI <4.0 l/min/m² and peak B-lines <15 (hypoperfusion without congestion, n = 13); and (4) peak CI <4.0 l/min/m² and peak B-lines ≥15 (congestion and hypoperfusion, n = 22). There were 21 cardiovascular deaths and 18 hospitalizations for worsening HF during a median follow-up of 29 months. Multivariate predictors of the combined end point were peak hemodynamic profiles (hazard ratio [HR] 1.62, 95% confidence interval [CI] 1.19 to 2.21; p = 0.002), B-type natriuretic peptide (HR 1.00, 95% CI 1.00 to 1.01; p = 0.001), and rest E/e' (HR 1.09, 95% CI 1.03 to 1.15; p = 0.002). Survival analysis showed a worse survival in patients with ESE-derived D profile, followed by patients with C, B, and A profile (log-rank: chi-square = 40.5; p <0.0001). In conclusion, dual evaluation of CI and LUS during ESE is useful for risk stratification of HF patients with reduced ejection fraction. Evidence of pulmonary congestion and low CI at peak ESE identifies a subgroup with a very high risk of adverse outcome.

Lung Ultrasound Guided Fluid Management Protocol for the Critically Ill Patient: study protocol for a multi-centre randomized controlled trial

Background

In routine intensive care unit (ICU) practice, fluids are often administered without a safety limit, which may lead to fluid overload and decreased survival. Recently, B-lines score (BLS) has been validated as a lung ultrasound (LUS) quantification of pulmonary congestion. This suggests that LUS may provide a safety threshold to conduct fluid therapy and to avoid overhydration. However, there is no randomized study to test the utility of LUS in guiding fluid management in ICU patients by using a pre-specified BLS cut-off value as a threshold for fluid removal.

Methods

LUS Guided Fluid Management Protocol for the Critically Ill Patient is a prospective, multi-centre, randomized controlled trial. Five hundred ICU patients will be randomly assigned in a 1:1 ratio, to protocolized LUS-based fluid management or usual care. The trial intervention will start on ICU admission and will consist in daily assessment of BLS and triggered evacuation of excessive fluids with loop diuretics (Furosemide) when BLS ≥ 15. If rebalancing volume status with diuretics fails, forced evacuation by ultrafiltration will be used. The main endpoint is death from all causes at 28 days from randomization. The secondary outcomes are presence and time-course evolution of organ dysfunctions, ICU- and hospital length of stay, all-cause mortality at 90 days, and health economics data.

Discussion

If study results will show that LUS guided fluid management protocol improves outcome in ICU patients, it will be the base for other studies to refine this protocol or track those categories of critically ill patients to whom it may bring maximum benefits.

Trial registration

ClinicalTrials.gov, NCT03393065. Registered on 8 January 2018.

Electronic supplementary material

The online version of this article (10.1186/s13063-019-3345-0) contains supplementary material, which is available to authorized users.

Extravascular lung water monitoring for thoracic and lung transplant surgeries

PURPOSE OF REVIEW

Excessive accumulation of extravascular lung water (EVLW) resulting in pulmonary edema is the most feared complication following thoracic surgery and lung transplant. ICUs have long relied on chest radiography to monitor pulmonary status postoperatively but the increasing recognition of the limitations of bedside plain films has fueled development of newer technologies, which offer earlier detection, quantitative assessments, and can aide in preoperative screening of surgical candidates. In this review, we focus on the emergence of transpulmonary thermodilution (TPTD) and lung ultrasound with a focus on the clinical integration of these modalities into current intraoperative and critical care practices.

RECENT FINDINGS

Recent studies demonstrate transpulmonary thermodilution and lung ultrasound provide greater sensitivity and earlier detection of lung water accumulation and are useful to guide clinical management. Assessments from these techniques have predictive value of postoperative outcome. Further, EVLW assessment shows promise as a preoperative screening tool in lung transplant patients.

SUMMARY

Monitoring EVLW in the perioperative period offers clinicians a powerful tool to guide fluid therapy and manage pulmonary edema. Both TPTD and lung ultrasound have unique attributes in the care of thoracic surgery and lung transplant patients.

Rapid cardiothoracic ultrasound protocol for diagnosis of acute heart failure in the emergency department

OBJECTIVES

The aim of this study was to evaluate the performance of a rapid cardiothoracic ultrasound protocol (CaTUS), combining echocardiographically derived E/e' and lung ultrasound (LUS), for diagnosing acute heart failure (AHF) in patients with undifferentiated dyspnea in an emergency department (ED).

PATIENTS AND RESULTS

We enrolled 100 patients with undifferentiated dyspnea from a tertiary care ED, who all had CaTUS done immediately upon arrival in the ED. CaTUS was positive for AHF with an E/e' > 15 and congestion, that is bilateral B-lines or bilateral pleural fluid, on LUS. In addition, an inferior vena cava index was also recorded to analyze whether including a central venous pressure estimate would add diagnostic benefit to the CaTUS protocol. All 100 patients had a brain natriuretic peptide (BNP) sample withdrawn, and 96 patients underwent chest radiography in the ED, which was analyzed later by a blinded radiologist. The reference diagnosis of AHF consisted of either a BNP of more than 400 ng/l or a BNP of less than 100 ng/l in combination with congestion on chest radiography and structural heart disease on conventional echocardiography.CaTUS had a sensitivity of 100% (95% confidence interval: 91.4-100%), a specificity of 95.8% (95% confidence interval: 84.6-99.3%), and an area under the curve of 0.979 for diagnosing AHF (P<0.001). The diagnostic accuracy of CaTUS was higher than of either E/e' or LUS alone. Adding the inferior vena cava index to CaTUS did not improve diagnostic accuracy. CaTUS seemed helpful also for differential diagnostics of dyspnea, mainly regarding pneumonias and pulmonary embolisms.

CONCLUSION

CaTUS, combining E/e' and LUS, provided excellent accuracy for diagnosing AHF.

A quantitative method for measuring the changes of lung surface wave speed for assessing disease progression of interstitial lung disease

Lung ultrasound surface wave elastography (LUSWE) is a novel non-invasive technique for measuring superficial lung tissue stiffness. The purpose of the study described here was to develop LUSWE for assessment of progression in patients with interstitial lung disease (ILD). In this study, LUSWE was used to measure changes in lung surface wave speeds at 100, 150 and 200 Hz through six intercostal lung spaces for 52 patients with ILD. The mean age was 63.1 ± 12.0 y (range: 20-85, 23 male and 29 female). The follow-up interval was 9.2 ± 3.5 mo depending on each patient's return appointment and availability. For each patient, disease progression between the baseline and follow-up tests was evaluated clinically using a 7-point Likert scale comprising three grades of improvement (mild, moderate, marked), unchanged status and three grades of worsening (mild, moderate, marked). Clinical assessments were based on changes in pulmonary function tests together with high-resolution computed tomography, echocardiography and clinical evaluations. This study illustrates the correlations between changes in lung surface wave speed and clinical assessments. Correlations of changes in lung surface wave speed at lower lateral and posterior portions of the lung portions with clinical assessments were good. LUSWE provides quantitative global and regional changes in lung surface wave speed that may be useful for quantitative assessment of progression of ILD.

Prevalence, pattern and clinical relevance of ultrasound indices of congestion in outpatients with heart failure

AIMS

Even if treatment controls symptoms, patients with heart failure may still be congested. We aimed at assessing the prevalence and clinical relevance of congestion in outpatients with chronic heart failure.

METHODS AND RESULTS

We recorded clinical and ultrasound [lung B-lines; inferior vena cava (IVC) diameter; internal jugular vein diameter before and after a Valsalva manoeuvre (JVD ratio)] features of congestion in heart failure patients during a routine check-up. Of 342 patients who attended, predominantly in New York Heart Association class I or II (n = 257; 75%), 242 (71%) had at least one feature of congestion, either clinical (n = 139; 41%) or by ultrasound (n = 199; 58%). Amongst patients (n = 203, 59%) clinically free of congestion, 31 (15%) had ≥ 14 B-lines, 57 (29%) had a dilated IVC (> 2.0 cm), 38 (20%) had an abnormal JVD ratio (< 4), 87 (43%) had at least one of these, and 27 (13%) had two or more. During a median follow-up of 234 (interquartile range 136-351) days, 60 patients (18%) died or were hospitalized for heart failure. In univariable analysis, each clinical and ultrasound measure of congestion was associated with increased risk but, in multivariable models, only higher N-terminal pro-B-type natriuretic peptide and IVC, and lower JVD ratio, were associated with the composite outcome.

CONCLUSIONS

Many patients with chronic heart failure with few symptoms have objective evidence of congestion and this is associated with an adverse prognosis. Whether using these measures of congestion to guide management improves outcomes requires investigation.

Anterior vs lateral symmetric interstitial syndrome in the diagnosis of acute heart failure

Acute dyspnea due to acute heart failure (AHF) is one of the most common reasons for admission to the Emergency Department (ED). The importance of lung ultrasound (LUS) examination in the diagnostic workup of AHF has been widely established. Limited anterior LUS examination for the diagnosis of AHF is controversial. This study compares the accuracy of LUS examination limited to the anterior or lateral lung zones for the diagnosis of AHF and their accuracy among patients with different levels of hypoxemia according to PO₂/FiO₂ ratio evaluation. We analyzed 170 patients admitted to the ED for acute dyspnea, who underwent multi-organ ultrasound examination of lung, heart and inferior vena cava for differential diagnosis. The thorax was examined following a simplified protocol that provides two scans at each side (anterior and lateral) to sample upper and lower lobes and the presence or the absence of interstitial syndrome (IS) was evaluated. The presence of anterior symmetric IS exhibited lower accuracy than lateral symmetric IS in the diagnosis of AHF in the whole population, but its diagnostic accuracy improves in sub-groups of patients with severe and critical hypoxemia.

The role of ultrasound lung artifacts in the diagnosis of respiratory diseases

INTRODUCTION

Thoracic ultrasound is employed for the diagnosis of many thoracic diseases and is an accepted detection tool of pleural effusions, atelectasis, pneumothorax, and pneumonia. However, the use of ultrasound for the evaluation of parenchymal lung disease, when the organ is still aerated, is a relatively new application. Areas covered: The diagnosis of a normal lung and the differentiation between a normally aerated lung and a lung with interstitial pathology is based on the interpretation of ultrasound artifacts universally known as A and B-Lines. Even though the practical role of lung ultrasound artifacts is accepted by many clinicians, their physical basis and the correlations between these signs and the causal pathology is not known in depth. Expert commentary: In this review, we discuss the meaning of A- and B-Lines in the diagnostic ultrasound imaging of the lung and the acoustic properties of the pleural plane which are at the basis of their generation.

Point-of-care lung ultrasound for the detection of pulmonary manifestations of malaria and sepsis: An observational study

INTRODUCTION

Patients with severe malaria or sepsis are at risk of developing life-threatening acute respiratory distress syndrome (ARDS). The objective of this study was to evaluate point-of-care lung ultrasound as a novel tool to determine the prevalence and early signs of ARDS in a resource-limited setting among patients with severe malaria or sepsis.

MATERIALS AND METHODS

Serial point-of-care lung ultrasound studies were performed on four consecutive days in a planned sub study of an observational cohort of patients with malaria or sepsis in Bangladesh. We quantified aeration patterns across 12 lung regions. ARDS was defined according to the Kigali Modification of the Berlin Definition.

RESULTS

Of 102 patients enrolled, 71 had sepsis and 31 had malaria. Normal lung ultrasound findings were observed in 44 patients on enrolment and associated with 7% case fatality. ARDS was detected in 10 patients on enrolment and associated with 90% case fatality. All patients with ARDS had sepsis, 4 had underlying pneumonia. Two patients developing ARDS during hospitalisation already had reduced aeration patterns on enrolment. The SpO2/FiO2 ratio combined with the number of regions with reduced aeration was a strong prognosticator for mortality in patients with sepsis (AUROC 91.5% (95% Confidence Interval: 84.6%-98.4%)).

CONCLUSIONS

This study demonstrates the potential usefulness of point-of-care lung ultrasound to detect lung abnormalities in patients with malaria or sepsis in a resource-constrained hospital setting. LUS was highly feasible and allowed to accurately identify patients at risk of death in a resource limited setting.

A Lung Phantom Model to Study Pulmonary Edema Using Lung Ultrasound Surface Wave Elastography

Lung ultrasound surface wave elastography (LUSWE) is a novel technique used to measure superficial lung tissue stiffness. A phantom study was carried out in the study described here to evaluate the application of LUSWE to assess lung water for pulmonary edema. A lung phantom model with cellulose sponge was used; various volumes of water were injected into the sponge to model lung water. Shaker-generated surface wave propagation on the sponge surface was recorded by a 10-MHz ultrasound probe at three shaker frequencies: 100, 150 and 200Hz. Surface wave speeds were calculated but did not exhibit dependence on the volume of injected water. However, the shear viscosity of the sponge increased with water content, and shear elasticity also exhibited a subtle increase. This study suggests that sponge viscoelasticity might change with the water content, which can be detected by LUSWE.

Feasibility of lung ultrasound to assess pulmonary overflow in congenital heart disease children

BACKGROUND

Pulmonary overflow (PO) is one of the most common complications in congenital heart disease (CHD) children with an incidence of 48-60% approximately. This study explored the feasibility of using lung ultrasound (LUS) to assess pulmonary overcirculation in CHD children and compare the diagnostic performance of LUS and chest radiography (CXR) for the detection of pulmonary overcirculation.

METHOD

The upper anterior area, lower anterior area, upper lateral area, and lower posterior area, in each hemithorax were scanned in 59 children in the supine position. A-lines, B-lines in each scanned region were recorded, and the worst LUS abnormality in the video clip was considered to characterize the examined region. Sensitivity, specificity, positive and negative predictive values, and diagnostic accuracy of LUS and CXR were compared using computed tomography (CT) as a standard criterion.

RESULTS

PO was diagnosed in 53% (31/59), 63% (37/59), and 51% (30/59) children with CT, CXR, and LUS, respectively. The sensitivity, specificity, and diagnostic accuracy of PO were 96%, 94%, and 95% for LUS and 74%, 50%, and 63% for CXR. The percentage of mild, moderate, and severe PO diagnosed via LUS were 31% (18/59), 19% (11/59), and 2% (1/59), respectively. Furthermore, the PO incidence diagnosed by LUS in CHD children less than 1 year old were significantly higher than those beyond 1 year old.

CONCLUSION

LUS is a noninvasive and useful tool for the detection and assessment of PO in CHD children at the operating room, and is better than CXR in sensitivity and specificity, comparable to CT.

[Emergency lung ultrasound]

Acute and emergency physicians need to make rapid and far-reaching decisions on the basis of little diagnostic information. In patients with symptoms suggestive of a cardiopulmonary diagnosis, point-of-care lung ultrasound (LUS) is becoming increasingly used. In patients with acute dyspnea, chest pain and shock, LUS increases the diagnostic reliability. The BLUE protocol helps to differentiate important diagnoses of acute dyspnea (pulmonary edema, pneumonia, acute respiratory distress syndrome, pulmonary embolism, pleural effusions or pneumothorax). LUS is also used for treatment follow-up. It is clearly superior to other diagnostic measures (auscultation, chest X‑ray). With ever smaller "handheld" ultrasound devices, the use of ultrasound is also being increasingly used in preclinical situations.

[Pulmonary ultrasound and dialysis]

Profound deficit of the body fluid composition regulation system is present at the end stage kidney disease, leading to the increase the risk of acute or chronic volume overload, which impacts the morbidity and mortality in these patients. Pulmonary ultrasound by its ability to estimate extrapulmonary water at an infraclinical stage has helped to make progress in this area. Line B is the element of fundamental semiology that reflects the presence of water in the pulmonary alveoli. The alteration of left ventricular function and the increase of pulmonary capillary permeability are the determining factors in the genesis of subclinical pulmonary congestion and are positively correlated with B-lines. Because of its non-invasive nature, its ease of use, its intra- and interoperability reproducibility and its ease of learning, nephrologists can be efficiently and quickly trained to use it to measure pulmonary congestion. Recent data have shown an epidemiological association between B-lines and mortality in end stage kidney disease patients. The causal role of subclinical pulmonary congestion assessed by these B lines in the genesis of detrimental events is being evaluated by a randomized, multicentre, open-label European clinical trial (Lung water by ultra-sound guided treatment [LUST] trial). The clinical usefulness of pulmonary ultrasound in the management of subclinical pulmonary congestion in patients with end stage kidney disease remains to be determined, but it could be considered from now as an additional tool to improve the management of this congestion, possibly by complementing bioimpedancemetry data.

The new clinical standard of integrated quadruple stress echocardiography with ABCD protocol

BACKGROUND

The detection of regional wall motion abnormalities is the cornerstone of stress echocardiography. Today, stress echo shows increasing trends of utilization due to growing concerns for radiation risk, higher cost and stronger environmental impact of competing techniques. However, it has also limitations: underused ability to identify factors of clinical vulnerability outside coronary artery stenosis; operator-dependence; low positivity rate in contemporary populations; intermediate risk associated with a negative test; limited value of wall motion beyond coronary artery disease. Nevertheless, stress echo has potential to adapt to a changing environment and overcome its current limitations.

INTEGRATED-QUADRUPLE STRESS-ECHO

Four parameters now converge conceptually, logistically, and methodologically in the Integrated Quadruple (IQ)-stress echo. They are: 1- regional wall motion abnormalities; 2-B-lines measured by lung ultrasound; 3-left ventricular contractile reserve assessed as the stress/rest ratio of force (systolic arterial pressure by cuff sphygmomanometer/end-systolic volume from 2D); 4- coronary flow velocity reserve on left anterior descending coronary artery (with color-Doppler guided pulsed wave Doppler). IQ-Stress echo allows a synoptic functional assessment of epicardial coronary artery stenosis (wall motion), lung water (B-lines), myocardial function (left ventricular contractile reserve) and coronary small vessels (coronary flow velocity reserve in mid or distal left anterior descending artery). In "ABCD" protocol, A stands for Asynergy (ischemic vs non-ischemic heart); B for B-lines (wet vs dry lung); C for Contractile reserve (weak vs strong heart); D for Doppler flowmetry (warm vs cold heart, since the hyperemic blood flow increases the local temperature of the myocardium). From the technical (acquisition/analysis) viewpoint and required training, B-lines are the kindergarten, left ventricular contractile reserve the primary (for acquisition) and secondary (for analysis) school, wall motion the university, and coronary flow velocity reserve the PhD program of stress echo.

CONCLUSION

Stress echo is changing. As an old landline telephone with only one function, yesterday stress echo used one sign (regional wall motion abnormalities) for one patient with coronary artery disease. As a versatile smart-phone with multiple applications, stress echo today uses many signs for different pathophysiological and clinical targets. Large scale effectiveness studies are now in progress in the Stress Echo2020 project with the omnivorous "ABCD" protocol.

Quality control of B-lines analysis in stress Echo 2020

BACKGROUND

The effectiveness trial "Stress echo (SE) 2020" evaluates novel applications of SE in and beyond coronary artery disease. The core protocol also includes 4-site simplified scan of B-lines by lung ultrasound, useful to assess pulmonary congestion.

PURPOSE

To provide web-based upstream quality control and harmonization of B-lines reading criteria.

METHODS

60 readers (all previously accredited for regional wall motion, 53 B-lines naive) from 52 centers of 16 countries of SE 2020 network read a set of 20 lung ultrasound video-clips selected by the Pisa lab serving as reference standard, after taking an obligatory web-based learning 2-h module ( http://se2020.altervista.org ). Each test clip was scored for B-lines from 0 (black lung, A-lines, no B-lines) to 10 (white lung, coalescing B-lines). The diagnostic gold standard was the concordant assessment of two experienced readers of the Pisa lab. The answer of the reader was considered correct if concordant with reference standard reading ±1 (for instance, reference standard reading of 5 B-lines; correct answer 4, 5, or 6). The a priori determined pass threshold was 18/20 (≥ 90%) with R value (intra-class correlation coefficient) between reference standard and recruiting center) > 0.90. Inter-observer agreement was assessed with intra-class correlation coefficient statistics.

RESULTS

All 60 readers were successfully accredited: 26 (43%) on first, 24 (40%) on second, and 10 (17%) on third attempt. The average diagnostic accuracy of the 60 accredited readers was 95%, with R value of 0.95 compared to reference standard reading. The 53 B-lines naive scored similarly to the 7 B-lines expert on first attempt (90 versus 95%, p = NS). Compared to the step-1 of quality control for regional wall motion abnormalities, the mean reading time per attempt was shorter (17 ± 3 vs 29 ± 12 min, p < .01), the first attempt success rate was higher (43 vs 28%, p < 0.01), and the drop-out of readers smaller (0 vs 28%, p < .01).

CONCLUSIONS

Web-based learning is highly effective for teaching and harmonizing B-lines reading. Echocardiographers without previous experience with B-lines learn quickly.

Lung mass density analysis using deep neural network and lung ultrasound surface wave elastography

Lung mass density is directly associated with lung pathology. Computed Tomography (CT) evaluates lung pathology using the Hounsfield unit (HU) but not lung density directly. We have developed a lung ultrasound surface wave elastography (LUSWE) technique to measure the surface wave speed of superficial lung tissue. The objective of this study was to develop a method for analyzing lung mass density of superficial lung tissue using a deep neural network (DNN) and synthetic data of wave speed measurements with LUSWE. The synthetic training dataset of surface wave speed, excitation frequency, lung mass density, and viscoelasticity from LUSWE (788,000 in total) was used to train the DNN model. The DNN was composed of 3 hidden layers of 1024 neurons for each layer and trained for 10 epochs with a batch size of 4096 and a learning rate of 0.001 with three types of optimizers. The test dataset (4000) of wave speeds at three excitation frequencies (100, 150, and 200 Hz) and shear elasticity of superficial lung tissue was used to predict the lung density and evaluate its accuracy compared with predefined lung mass densities. This technique was then validated on a sponge phantom experiment. The obtained results showed that predictions matched well with test dataset (validation accuracy is 0.992) and experimental data in the sponge phantom experiment. This method may be useful to analyze lung mass density by using the DNN model together with the surface wave speed and lung stiffness measurements.

Acute Heart Failure Management

Acute heart failure (AHF) is a life-threatening medical condition, where urgent diagnostic and treatment methods are of key importance. However, there are few evidence-based treatment methods. Interestingly, despite relatively similar ways of management of AHF throughout the globe, mid-term outcome in East Asia, including South Korea is more favorable than in Europe. Yet, most of the treatment methods are symptomatic. The cornerstone of AHF management is identifying precipitating factors and specific phenotype. Multidisciplinary approach is important in AHF, which can be caused or aggravated by both cardiac and non-cardiac causes. The main pathophysiological mechanism in AHF is congestion, both systemic and inside the organs (lung, kidney, or liver). Cardiac output is often preserved in AHF except in a few cases of advanced heart failure. This paper provides guidance on AHF management in a time-based approach. Treatment strategies, criteria for triage, admission to hospital and discharge are described.

Lung ultrasound as a translational approach for non-invasive assessment of heart failure with reduced or preserved ejection fraction in mice

Aims

Heart failure (HF) has become an epidemic and constitutes a major medical, social, and economic problem worldwide. Despite advances in medical treatment, HF prognosis remains poor. The development of efficient therapies is hampered by the lack of appropriate animal models in which HF can be reliably determined, particularly in mice. The development of HF in mice is often assumed based on the presence of cardiac dysfunction, but HF itself is seldom proved. Lung ultrasound (LUS) has become a helpful tool for lung congestion assessment in patients at all stages of HF. We aimed to apply this non-invasive imaging tool to evaluate HF in mouse models of both systolic and diastolic dysfunction.

Methods and results

We used LUS to study HF in a mouse model of systolic dysfunction, dilated cardiomyopathy, and in a mouse model of diastolic dysfunction, diabetic cardiomyopathy. LUS proved to be a reliable and reproducible tool to detect pulmonary congestion in mice. The combination of LUS and echocardiography allowed discriminating those mice that develop HF from those that do not, even in the presence of evident cardiac dysfunction. The study showed that LUS can be used to identify the onset of HF decompensation and to evaluate the efficacy of therapies for this syndrome.

Conclusions

This novel approach in mouse models of cardiac disease enables for the first time to adequately diagnose HF non-invasively in mice with preserved or reduced ejection fraction, and will pave the way to a better understanding of HF and to the development of new therapeutic approaches.

A plea for an early ultrasound-clinical integrated approach in patients with acute heart failure. A proactive comment on the ESC Guidelines on Heart Failure 2016

BACKGROUND

The European Association of Cardiology (ESC) Guidelines on the diagnosis and treatment of acute heart failure (AHF) indicate prompt therapy initiation and performance of relevant investigations as paramount. Specifically, echocardiography prior to treatment is advocated only with hemodynamic instability, and the evaluation of clinical signs of peripheral perfusion and congestion is suggested as guidance for early interventions. Given the growing body of evidence on the diagnostic/monitoring capabilities of bedside ultrasound (including focused cardiac ultrasound, comprehensive echocardiography, lung ultrasound), we discuss the potential benefit of an integrated clinical/ultrasound approach at the very early stages of acute heart failure.

METHODS AND RESULTS

We proposed a narrative review of the current evidence on the clinical-ultrasound integrated approach to AHF, with special emphasis on the components of the early diagnostic-therapeutic workup where cardiac, inferior vena cava and lung ultrasound showed high diagnostic accuracy and the capability of substantially changing an exclusively clinically-oriented patient management. A proactive comment to the ESC guidelines is made, suggesting an integration of clinical and biochemical assessment, as defined by guidelines, with combined bedside ultrasound on may help in the definition of AHF pathophysiology and treatment.

CONCLUSION

A multi-organ integrated clinical-ultrasound approach should be advocated as part of the clinical-diagnostic workup at AHF very early phase. Whenever competence and technology available, bedside ultrasound, along with clinical and biochemical assessment, should target AHF profiling, identify the cause of AHF, and subsequently aid disease course and response to treatment monitoring.

Remote Left Ventricular Hemodynamic Monitoring Using a Novel Intracardiac Sensor

BACKGROUND

Heart failure (HF) remains the most common reason for hospital admission in patients aged >65 years. Despite modern drug therapy, mortality and readmission rates for patients hospitalized with HF remain high. This necessitates further research to identify early patients at risk for readmission to limit hospitalization by timely adjustment of medical therapy. Implantable devices can monitor left ventricular (LV) hemodynamics and remotely and continuously detect the early signs of decompensation to trigger interventions and reduce the risk of hospitalization for HF. Here, we report the first preclinical study validating a new batteryless and easy to implant LV-microelectromechanical system to assess LV performance.

METHODS AND RESULTS

A miniaturized implantable wireless pressure sensor was adapted for implantation in the LV apex. The LV-microelectromechanical system sensor was tested in a canine model of HF. The wireless pressure sensor measurements were compared with invasive left heart catheter-derived measurements at several time points. During different pharmacological challenge studies with dobutamine or vasopressin, the device was equally sensitive compared with invasive standard procedures. No adverse events or any observable reaction related to the implantation and application of the device for a period of 35 days was observed.

CONCLUSIONS

Our miniaturized wireless pressure sensor placed in the LV (LV-microelectromechanical system) has the potential to become a new telemetric tool to earlier identify patients at risk for HF decompensation and to guide the treatment of patients with HF.

Integrated quadruple stress echocardiography

Stress echocardiography (SE) is an established diagnostic technique. For 40 years, the cornerstone of the technique has been the detection of regional wall motion abnormalities (RWMA), due to the underlying physiologically-relevant epicardial coronary artery stenosis. In the last decade, three new parameters (more objective than RWMA) have shown the potential to integrate and complement RWMA: 1) B-lines, also known as ultrasound lung comets, as a marker of extravascular lung water, measured using lung ultrasound with the 4-site simplified scan symmetrically of the antero-lateral thorax on the third intercostal space, from mid-axillary to anterior axillary and mid-clavicular line; 2) left ventricular contractile reserve (LVCR), assessed as the peak stress/rest ratio of left ventricular force, also known as elastance (systolic arterial pressure by cuff sphygmomanometer/end-systolic volume from 2D echocardiography); 3) coronary flow velocity reserve (CFVR) on left anterior descending coronary artery, calculated as peak stress/rest ratio of diastolic peak flow velocity assessed using pulsed-wave Doppler. The 4 parameters (RWMA, B-lines, LVCR and CFVR) now converge conceptually, logistically, and methodologically in the Integrated Quadruple (IQ)-SE. IQ-SE optimizes the versatility of SE to include in a one-stop shop the core "ABCD" (asynergy+B-lines+contractile reserve+Doppler flowmetry) protocol. It allows a synoptic assessment of parameters mirroring the epicardial artery stenosis (RWMA), interstitial lung water (B-lines), myocardial function (LVCR) and small coronary vessels (CFVR). Each variable has a clear clinical correlate, different and complementary to all others: RWMA identify an ischemic vs. non-ischemic heart; B-lines a wet vs. dry lung; LVCR a strong vs. weak heart; CFVR a warm vs. cold heart. IQ-SE is highly feasible, with minimal increase in the imaging and analysis time, and obvious diagnostic and prognostic impact also beyond coronary artery disease - especially in heart failure. Large scale effectiveness studies with IQ-SE are now under way with the Stress Echo 2020 Study, and will provide the necessary evidence base prior to large scale acceptance of the technique.

Stressing the Cardiopulmonary Vascular System: The Role of Echocardiography

The cardiopulmonary vascular system represents a key determinant of prognosis in several cardiorespiratory diseases. Although right heart catheterization is considered the gold standard for assessing pulmonary hemodynamics, a comprehensive noninvasive evaluation including left and right ventricular reserve and function and cardiopulmonary interactions remains highly attractive. Stress echocardiography is crucial in the evaluation of many cardiac conditions, typically coronary artery disease but also heart failure and valvular heart disease. In stress echocardiographic applications beyond coronary artery disease, the assessment of the cardiopulmonary vascular system is a cornerstone. The possibility of coupling the left and right ventricles with the pulmonary circuit during stress can provide significant insight into cardiopulmonary physiology in healthy and diseased subjects, can support the diagnosis of the etiology of pulmonary hypertension and other conditions, and can offer valuable prognostic information. In this state-of-the-art document, the topic of stress echocardiography applied to the cardiopulmonary vascular system is thoroughly addressed, from pathophysiology to different stress modalities and echocardiographic parameters, from clinical applications to limitations and future directions.

Toward a Reasoned Classification of Diseases Using Physico-Chemical Based Phenotypes

Background: Diseases and health conditions have been classified according to anatomical site, etiological, and clinical criteria. Physico-chemical mechanisms underlying the biology of diseases, such as the flow of energy through cells and tissues, have been often overlooked in classification systems.

Objective: We propose a conceptual framework toward the development of an energy-oriented classification of diseases, based on the principles of physical chemistry.

Methods: A review of literature on the physical chemistry of biological interactions in a number of diseases is traced from the point of view of the fluid and solid mechanics, electricity, and chemistry.

Results: We found consistent evidence in literature of decreased and/or increased physical and chemical forces intertwined with biological processes of numerous diseases, which allowed the identification of mechanical, electric and chemical phenotypes of diseases.

Discussion: Biological mechanisms of diseases need to be evaluated and integrated into more comprehensive theories that should account with principles of physics and chemistry. A hypothetical model is proposed relating the natural history of diseases to mechanical stress, electric field, and chemical equilibria (ATP) changes. The present perspective toward an innovative disease classification may improve drug-repurposing strategies in the future.

Assessment of left atrial size in addition to focused cardiopulmonary ultrasound improves diagnostic accuracy of acute heart failure in the Emergency Department

BACKGROUND

Acute dyspnea is one of the main reasons for admission to Emergency Department (ED). Availability of ultraminiaturized pocket ultrasound devices (PUD) adds diagnostic power to the clinical examination. The aim of this study was to identify an integrated ultrasound approach for diagnosis of acute heart failure (acute HF), using PUD and combining evaluation from lung, heart and inferior vena cava (IVC).

METHODS

We included 102 patients presenting to the ED of "Antonio Cardarelli" Hospital in Naples (Italy) for acute dyspnea (AD). All patients underwent integrated ultrasound examination (IUE) of lung-heart-IVC, using PUD. The gold standard was the final diagnosis determined by two expert reviewers: acute heart failure (acute HF) or noncardiac dyspnea. We used 2 × 2 contingency tables to analyze sensitivity, specificity, positive and negative predictive value and accuracy of the three ultrasonic methods, and their combinations for the diagnosis of acute HF, comparing with the final, validated diagnosis.

RESULTS

Lung ultrasound (LUS) alone exhibited a good sensitivity (100%) and specificity (82%) and had the highest accuracy (89%) among single modalities (heart and IVC) for the diagnosis of acute HF. The highest accuracy among all methods (96%) was obtained by the combination of positive LUS and either dilated left atrium or EF ≤ 40% or both (all P < .01 vs single modalities).

CONCLUSION

In patients presenting to ED, IUE using PUD is a useful extension of clinical examination and has a reliable diagnostic discriminant ability in the immediate evaluation of acute dyspnea. The combination of positive LUS with focused cardiac ultrasonography (FoCUS), including also dilated left atrium, substantially extends the spectrum of recognizable acute HF.

Pulmonary Congestion by Lung Ultrasound in Ambulatory Patients With Heart Failure With Reduced or Preserved Ejection Fraction and Hypertension

BACKGROUND

Although pulmonary congestion can be quantified in heart failure (HF) by means of lung ultrasonography (LUS), little is known about LUS findings (B-lines) in different HF phenotypes. This prospective cohort study investigated the prevalence and clinical and echocardiographic correlates of B-lines in ambulatory HF patients with preserved (HFpEF) or reduced (HFrEF) ejection fraction compared with hypertensive patients. We related LUS findings to 12-month HF hospitalizations and all-cause mortality.

METHODS AND RESULTS

We used LUS to examine hypertensive (n = 111), HFpEF (n = 46), and HFrEF (n = 73) patients (median age 66 y, 56% male, 79% white, and median EF 55%) undergoing clinically indicated outpatient echocardiography. B-line number was quantified offline, across 8 chest zones, blinded to clinical and echocardiographic characteristics. The proportion of patients with ≥3 B-lines was lower in hypertensive patients (13.5%) compared with both HFrEF (45.2%, P < .001) and HFpEF (34.8%; P = .05). HF patients with ≥3 B-lines had a higher risk of the composite outcome (age- and sex-adjusted hazard ratio 2.62, 95% confidence interval 1.15-5.96; P = .022).

CONCLUSIONS

When performed at the time of outpatient echocardiography, LUS findings of pulmonary congestion differ between patients with known HF and those with hypertension, and may be associated with adverse outcomes.

Clarifications on Continuous Renal Replacement Therapy and Hemodynamics

Objective:

Continuous renal replacement therapy (CRRT) is a continuous process of bedside blood purification which is widely used in the treatment of acute kidney injury (AKI) and for fluid management. However, since AKI and fluid overload are often found to be associated with hemodynamic abnormalities, determining the relationship between CRRT and hemodynamics remains a challenge in the treatment of critically ill patients. The aim of this review was to summarize key points in the relationship between CRRT and hemodynamics and to understand and monitor renal hemodynamics in critically ill patients, especially those with AKI.

Data Sources:

This review was based on data in articles published in the PubMed databases up to January 30, 2017, with the following keywords: “continuous renal replacement therapy,” “Hemodynamics,” and “Acute kidney injury.”

Study Selection:

Original articles and critical reviews on CRRT were selected for this review.

Results:

CRRT might treat AKI by hemodynamic therapy, and it was an important form of hemodynamic therapy. The targets of hemodynamic therapy should be established when using CRRT. Therefore, hemodynamic management and stability were very important during CRRT. Most studies suggested that renal hemodynamics should be clearly identified.

Conclusions:

CRRT is not only a replacement for organ function, but an important form of hemodynamic therapy. Improved hemodynamic management of critically ill patients can be achieved by establishing specific therapeutic hemodynamic targets and maintaining circulatory stability during CRRT. Over the long term, observation of renal hemodynamics will provide greater opportunities for the progression of CRRT hemodynamic therapy.

Point-of-care ultrasound in the practice of nephrology

Sonography is increasingly being performed by clinicians and has applications throughout the spectrum of nephrology, including acute and chronic renal failure, urinary obstruction, cystic disease, pain, hematuria, transplantation, kidney biopsy, temporary and permanent vascular access, and assessment of fluid status. The skill is relatively easily acquired, expedites patient care, and enhances the practice of nephrology. However, the lack of exposure in most training programs remains a major obstacle.

Evaluating Extravascular Lung Water in Sepsis: Three Lung-Ultrasound Techniques Compared against Transpulmonary Thermodilution

Background:

Excessive extravascular lung water (EVLW) is associated with increased morbidity and mortality. We compared three lung-ultrasound (L-US) techniques against the reference-standard transpulmonary thermodilution (TPTD) technique to access EVLW.

Materials and Methods:

This was a prospective, single-blind, cross-sectional study. Forty-four septic patients were enrolled. EVLW index was measured by the TPTD method, and an index of ≥10 mL/kg was considered diagnostic of pulmonary edema. EVLW index was then compared to three established bedside L-US protocols that evaluate sonographic B-lines: (1) a 28-zone protocol (total B-line score [TBS]) (2) a scanning 8-region examination, and (3) a 4-point examination.

Results:

Eighty-nine comparisons were obtained. A statistically significant positive correlation was found between L-US TBS and an EVLW index ≥10 mL/kg (r = 0.668,P < 0.001). The 28-zone protocol score ≥39 has a sensitivity of 81.6% and a specificity of 76.5% to define EVLW index ≥10 mL/kg. In contrast, the positive 4-point examination and scanning 8-regions showed low sensitivity (23.7% and 50.0%, respectively) but high specificity (96.1% and 88.2%, respectively). Ten patients with a total of 21 comparisons met criteria for acute respiratory distress syndrome (ARDS). In this subgroup, only the TBS had statistically significant positive correlation to EVLW (r = 0.488,P = 0.025).

Conclusion:

L-US is feasible in patients with severe sepsis. In addition, L-US 28-zone protocol demonstrated high specificity and better sensitivity than abbreviated 4- and 8-zone protocols. In ARDS, the L-US 28-zone protocol was more accurate than the 4- and 8-zone protocols in predicting EVLW. Consideration of limitations of the latter protocols may prevent clinicians from reaching premature conclusions regarding the prediction of EVLW.

Trial Registration:

ISRCTN11419081. Registered 4 February 2015 retrospectively.

Monitoring whole-lung lavage using lung ultrasound: The changing phases of the lung

Lung ultrasound (LUS) has been proven to yield valuable information for lung and pleural pathology. It is well validated for assessing extravascular lung water. It can also be used to monitor stages of controlled lung de-aeration in whole lung lavage (WLL) which is the treatment for Pulmonary Alveolar Protienosis (PAP),characterized by abnormal surfactant in the alveoli affecting gas exchange .LUS can help decide the point of termination of lung flooding. A 55 year old lady with biopsy proven pulmonary alveolar proteinosis presented with respiratory failure. WLL was planned. LUS was used to study the stages of lung flooding as previously described for ARDS model.6 areas screened based on six areas that are normally examined like upper zone, mid zone and lower zone showed alveolar interstitial pattern. One lung ventilation (OLV) was done and isolation of lavage lung was confirmed which was seen as lung collapse (lung pulse) on LUS. Saline infusion resulted in increase in B lines followed by tissue like pattern with fluid bronchogram on LUS(alveolar flooding) in all the areas. During the lavage of the second lung, appearance of alveolar flooding pattern resulted in termination of saline infusion. The use of LUS in monitoring WLL reduced amount of saline used for lavage, pick up complications like pleural effusion and spillage.

Lung Ultrasound and Pulmonary Function Test in Cirrhotic Patients

Lung ultrasound (LU) is useful in the diagnosis of pulmonary interstitial-alveolar syndrome (IAS) when B-lines are detected. Its prevalence and effect in lung function is not well studied in cirrhotic patients. The objective of this study was to detect the prevalence of interstitial-alveolar involvement with LU and correlate with pulmonary function test to distinguish the effect of ascites and B-lines in pulmonary function. This was an observational single-center study with 49 patients listed for liver transplantation submitted for LU and pulmonary function tests. Patients were divided into 4 groups: no ascites and no B-lines (n = 19), B-lines only (n = 19), ascites only (n = 6), and ascites and B-lines (n = 5). There was a worse forced vital capacity (FVC) in patients with B-lines only (76.1% ± 9.2; P = .0058) and ascites only (66.8% ± 10.2; P = .0010). 1-second forced expiratory volume (FEV₁) also was lower in patients with B-lines only (78.5% ± 10.3; P = .0001), ascites only (71.3% ± 13.2; P = .0004), and B-lines and ascites (74.2% ± 7.6; P = .0035). Model for End-Stage Liver Disease score was worse in the group with ascites and B-lines (22.4 ± 10.1; P = .0229). B-Lines reduced FVC and FEV₁ in our study and may be an independent factor in worsening pulmonary function in these patients.

Lung ultrasound B-lines in exacerbations of chronic obstructive pulmonary disease

We report on preliminary observations on performing lung ultrasound (LUS) in patients admitted to hospital with an exacerbation of chronic obstructive pulmonary disease (COPD). We found that LUS had high specificity and moderate sensitivity in identifying patients with elevated B-type natriuretic peptide. Thus, we hypothesise that LUS may have utility in screening COPD patients with an exacerbation to identify the sub-group with elevated natriuretic peptides and are at risk of increased cardiovascular mortality. The use of LUS in patients with acute and chronic respiratory disorders is increasing and its role in COPD patients is an interesting subject for future research.

B-lines with Lung Ultrasound: The Optimal Scan Technique at Rest and During Stress

Various lung ultrasound (LUS) scanning modalities have been proposed for the detection of B-lines, also referred to as ultrasound lung comets, which are an important indication of extravascular lung water at rest and after exercise stress echo (ESE). The aim of our study was to assess the lung water spatial distribution (comet map) at rest and after ESE. We performed LUS at rest and immediately after semi-supine ESE in 135 patients (45 women, 90 men; age 62 ± 12 y, resting left ventricular ejection fraction = 41 ± 13%) with known or suspected heart failure or coronary artery disease. B-lines were measured by scanning 28 intercostal spaces (ISs) on the antero-lateral chest, 2nd-5th IS, along with the midaxillary (MA), anterior axillary (AA), mid-clavicular (MC) and parasternal (PS) lines. Complete 28-region, 16-region (3rd and 4th IS), 8-region (3rd IS), 4-region (3rd IS, only AA and MA) and 1-region (left 3rd IS, MA) scans were analyzed. In each space, the B-lines were counted from 0 = black lung to 10 = white lung. Interpretable images were obtained in all spaces (feasibility = 100 %). B-lines (>0 in at least 1 space) were present at ESE in 93 patients (69%) and absent in 42. More B-lines were found in the 3rd IS and along AA and MA lines. The B-line cumulative distribution was symmetric at rest (right/left = 1.10) and asymmetric with left lung predominance during stress (right/left = 0.67). The correlation of per-patient B-line number between 28-S and 16-S (R² = 0.9478), 8-S (R² = 0.9478) and 4-S scan (R² = 0.9146) was excellent, but only good with 1-S (R² = 0.8101). The average imaging and online analysis time were 5 s per space. In conclusion, during ESE, the comet map of lung water accumulation follows a predictable spatial pattern with wet spots preferentially aligned with the third IS and along the AA and MA lines. The time-saving 4-region scan is especially convenient during stress, simply dismissing dry regions and focusing on wet regions alone.

Heart failure

Heart failure is common in adults, accounting for substantial morbidity and mortality worldwide. Its prevalence is increasing because of ageing of the population and improved treatment of acute cardiovascular events, despite the efficacy of many therapies for patients with heart failure with reduced ejection fraction, such as angiotensin converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs), β blockers, and mineralocorticoid receptor antagonists, and advanced device therapies. Combined angiotensin receptor blocker neprilysin inhibitors (ARNIs) have been associated with improvements in hospital admissions and mortality from heart failure compared with enalapril, and guidelines now recommend substitution of ACE inhibitors or ARBs with ARNIs in appropriate patients. Improved safety of left ventricular assist devices means that these are becoming more commonly used in patients with severe symptoms. Antidiabetic therapies might further improve outcomes in patients with heart failure. New drugs with novel mechanisms of action, such as cardiac myosin activators, are under investigation for patients with heart failure with reduced left ventricular ejection fraction. Heart failure with preserved ejection fraction is a heterogeneous disorder that remains incompletely understood and will continue to increase in prevalence with the ageing population. Although some data suggest that spironolactone might improve outcomes in these patients, no therapy has conclusively shown a significant effect. Hopefully, future studies will address these unmet needs for patients with heart failure. Admissions for acute heart failure continue to increase but, to date, no new therapies have improved clinical outcomes.

[Structured bedside-ultrasound in intensive care medicine]

The so-called point-of-care ultrasound (POCUS) is of increasing importance for diagnostics and therapy control in intensive care medicine. Based on focused thorax sonography, echocardiography, and abdominal sonography, the most important working and differential diagnoses can be demonstrated or excluded depending on the leading symptom. Sonographic-based algorithms allow a structured evaluation especially of patients with the common leading symptoms dyspnea and thoracic pain.

Simple six-item clinical score improves risk prediction capability of stress echocardiography

Objectives

To assess the value of a simple score integrating non-ischaemia-related variables in expanding the wall motion abnormalities risk power during stress echocardiography (SE).

Methods

Study includes 14 279 patients who underwent SE for evaluation of coronary artery disease. All-cause death was the end point. Patients were randomly divided into the modelling and validation group of equal size. In the modelling group, multivariate analysis was conducted using clinical, rest and SE data, and a score was obtained from the number of non-ischaemia-related independent prognostic predictors. The score prognostic capability was compared in both groups.

Results

During a median follow-up of 31 months, 1230 patients died: 622 (9%) in the modelling and 608 (9%) in the validation group (p=0.68). Independent predictors of mortality were ischaemia at SE (HR 1.77, 95% CI 1.49 to 2.12; p<0.0001) and six other parameters: age>65 years, wall motion at rest, diabetes, left bundle branch block, anti-ischaemic therapy and male sex. Risk score resulted prognostically effective in the modelling and validation groups, both with and without inducible ischaemia subset. When risk score was included in the multivariate analysis, besides ischaemia at SE it was the only independent predictor of mortality in the modelling (HR 1.70, 95% CI 1.60 to 1.82; p<0.0001), in the validation (HR 1.77, 95% CI 1.65 to 1.90; p<0.0001) and in the overall group (HR 1.73, 95% CI 1.66 to 1.82; p<0.0001).

Conclusions

Simple clinical variables may be able to optimise SE risk stratification.

The lung water cascade in heart failure

In heart failure patients, we hypothesize the occurrence of the "lung water cascade," with the various markers hierarchically ranked in a well-defined time sequence: (1) early, proximal hemodynamic event with increase in pulmonary capillary wedge pressure; (2) intermediate, direct imaging sign of pulmonary edema (easily detectable at bedside by lung ultrasound as B-lines); (3) late, distal clinical symptoms and signs such as dyspnea and pulmonary crackles. Completion of the cascade (from hemodynamic to pulmonary to clinical congestion) can require minutes (as with exercise), hours or even weeks (as with impending acute heart failure). Backward rewind of the downhill cascade can be achieved with timely pulmonary decongestion therapy, such as diuretics or dialysis, restoring a relatively dry lung. Any therapeutic intervention is more likely to succeed in the early steps of the cascade, at the imaging stage of asymptomatic pulmonary congestion, rather than downstream near to the end of the cascade, when clinical instability occurred.

Assessment of Pulmonary Edema: Principles and Practice

Pulmonary edema increasingly is recognized as a perioperative complication affecting outcome. Several risk factors have been identified, including those of cardiogenic origin, such as heart failure or excessive fluid administration, and those related to increased pulmonary capillary permeability secondary to inflammatory mediators. Effective treatment requires prompt diagnosis and early intervention. Consequently, over the past 2 centuries a concentrated effort to develop clinical tools to rapidly diagnose pulmonary edema and track response to treatment has occurred. The ideal properties of such a tool would include high sensitivity and specificity, easy availability, and the ability to diagnose early accumulation of lung water before the development of the full clinical presentation. In addition, clinicians highly value the ability to precisely quantify extravascular lung water accumulation and differentiate hydrostatic from high permeability etiologies of pulmonary edema. In this review, advances in understanding the physiology of extravascular lung water accumulation in health and in disease and the various mechanisms that protect against the development of pulmonary edema under physiologic conditions are discussed. In addition, the various bedside modalities available to diagnose early accumulation of extravascular lung water and pulmonary edema, including chest auscultation, chest roentgenography, lung ultrasonography, and transpulmonary thermodilution, are examined. Furthermore, advantages and limitations of these methods for the operating room and intensive care unit that are critical for proper modality selection in each individual case are explored.