Lung sonography and recruitment in patients with early acute respiratory distress syndrome: a pilot study

Ultrasonographic modeling of lung and diaphragm mechanics: clinical trial of a novel non-invasive method to evaluate pre-operative pulmonary function

Background

Pre-operative pulmonary function testing (PFT) plays a key role in predicting postoperative complications or functional impairment. However, PFT requires the subject and examiner to cooperate and the results are influenced by both technical and personal factors. In contrast, the use of ultrasound (US) for structural and functional assessments of the lungs and diaphragm is on the rise, as it requires minimal patient cooperation. Dyspnea is mainly caused by lung or pleural lesions but may also be caused by weak respiratory muscles. As the diaphragm is a primary respiratory muscle, combining lung ultrasonography (LUS) with diaphragm ultrasound (DUS) may enable a more comprehensive assessement of pulmonary function. This study aims to introduce a novel approach for assessing pulmonary function using a mathematical model based on LUS and DUS.

Methods

This prospective study was performed at the First Affiliated Hospital of Nanchang University between June 2021 and December 2021, 208 patients were recruited and underwent PFT, LUS, and DUS examinations. An experienced physician, blinded to the clinical history and PFT results, performed LUS and DUS and explored the correlations between a mathematical model (ultrasonographic modeling score (U-score)) using LUS combined with DUS and pulmonary function parameters. Univariate, multivariate, and logistic regression analyses were also performed.

Results

According to the univariate and multivariable analysis, diaphragm thickness fraction in deep breathing (D-DTF) (odds ratio (OR), 0.88; 95% confidence interval (CI) [0.83-0.94]; P < 0.001), and LUS score (OR, 1.44; 95% CI [1.16-1.80]; P < 0.001) were each independently associated with pulmonary function. According to the logistics equation, a U-score of -0.126 × D-DTF + 0.368 × LUS score was produced. The U-score showed a more significant negative correlation with forced expiratory volume in the first second/forced vital capacity (FEV1/FVC) (r = -0.605, P < 0.001) than the LUS or DUS indices alone. The U-score (area under the curve (AUC) = 0.971) was greater than the other indices for assessing pulmonary function.

Conclusions

With validation, the U-score through both lung and diaphragm ultrasound measurements may assist in estimating pulmonary function. This approach facilitates the assessment of pulmonary function in patients who may be unable to reliably participate in PFT.

Pleural lung sliding quantification using a speckle tracking technology: A feasibility study on 30 healthy volunteers

INTRODUCTION

Speckle tracking technology quantifies lung sliding and detects lung sliding abolition in case of pneumothorax on selected ultrasound loops through the analysis of acoustic markers.

OBJECTIVES

We aimed to test the ability of speckle tracking technology to quantify lung sliding using a pleural strain value (PS).

METHODS

We performed a prospective study in 30 healthy volunteers in whom we assessed the pleural speckle tracking using ultrasound loops. Seven breathing conditions with and without non-invasive ventilation were tested. Two observers analyzed the ultrasound loops in four lung areas (anterior and posterior, left and right) and compared the obtained PS values. The first endpoint was to determine the feasibility of the PS measurement in different breathing conditions. The secondary endpoints were to assess the intra- and inter-observer's reliability of the measurement to compare PS values between anterior and posterior lung areas and to explore their correlations with the measured tidal volume.

RESULTS

We analyzed 1624 ultrasound loops from 29 patients after one volunteer's exclusion. Feasibility of this method was rated at 90.8 [95%CI: 89.6 - 92.4]%. The intra-observer reliability measured through Intraclass Correlation Coefficients was 0.96 [95%CI: 0.91-0.98] and 0.93 [95%CI: 0.86-0.97] depending on the operator. The inter-observer reliability was 0.89 [95%CI: 0.78-0.95]. The PS values were significantly lower in the anterior lung areas compared with the posterior areas in all breathing conditions. A weak positive correlation was found in all the lung areas when a positive end expiratory pressure was applied with r = 0.26 [95%CI: 0.12;0.39]; p < 0.01.

CONCLUSION

Speckle tracking lung sliding quantification with PS was applicable in most conditions with an excellent intra- and inter-observer reliability. More studies in patients under invasive mechanical ventilation are needed to explore the correlation between PS values of pleural sliding and tidal volumes.

CLINICAL REGISTRATION

NCT05415605.

Recruitment-Potential-Oriented Mechanical Ventilation Protocol and Narrative Review for Patients with Acute Respiratory Distress Syndrome

Even though much progress has been made to improve clinical outcomes, acute respiratory distress syndrome (ARDS) remains a significant cause of acute respiratory failure. Protective mechanical ventilation is the backbone of supportive care for these patients; however, there are still many unresolved issues in its setting. The primary goal of mechanical ventilation is to improve oxygenation and ventilation. The use of positive pressure, especially positive end-expiratory pressure (PEEP), is mandatory in this approach. However, PEEP is a double-edged sword. How to safely set positive end-inspiratory pressure has long been elusive to clinicians. We hereby propose a pressure-volume curve measurement-based method to assess whether injured lungs are recruitable in order to set an appropriate PEEP. For the most severe form of ARDS, extracorporeal membrane oxygenation (ECMO) is considered as the salvage therapy. However, the high level of medical resources required and associated complications make its use in patients with severe ARDS controversial. Our proposed protocol also attempts to propose how to improve patient outcomes by balancing the possible overuse of resources with minimizing patient harm due to dangerous ventilator settings. A recruitment-potential-oriented evaluation-based protocol can effectively stabilize hypoxemic conditions quickly and screen out truly serious patients.

Lung ultrasound for the early diagnosis of acute lung injury: A case report

BACKGROUND

The extensive availability of ultrasound (US) technology has increased its use for point-of-care applications in many health care settings. During anaesthesia and surgery, acute respiratory failure or pulmonary oedema are common life-threatening events that, if not recognized and treated appropriately, result in a high mortality rate.

CASE SUMMARY

We report a patient under anaesthesia whose lung US examination showed multiple vertical artefacts (B-lines) in the lung tissue, indicating pulmonary oedema. The respiratory state improved with the resolution of the pulmonary oedema after our treatment.

CONCLUSION

We believe that US of the lungs may be a useful tool for dynamic respiratory monitoring at the bedside during anaesthesia.

Lung ultrasound to evaluate lung recruitment in neonates with respiratory distress (RELUS study)

BACKGROUND

Lung ultrasound (LUS) is a bedside tool useful to diagnose neonatal respiratory disease and to guide surfactant therapy. LUS scores have emerged as useful tool for newborn respiratory distress but is unknown if respiratory support settings may influence it. The aim of the study was to evaluate the feasibility of LUS scores evaluating lung recruitment in term newborns with respiratory distress when noninvasive respiratory it is increased.

MATERIAL AND METHODS

Prospective study in a tertiary neonatal intensive care unit. Inclusion criteria were term neonates with respiratory distress requiring noninvasive respiratory support with nasal continuous positive airway pressure (nCPAP) within first 6 h of life with an LUS score higher than 8 were enrolled. LUS was performed three times. First LUS (LUS-1) was done in patients in nCPAP (Fabian Device) (Acutronic) (pressure of 6 cmH2 O). Afterwards patients were placed in duo positive airway pressure (12/6 cmH2 O), a second LUS (LUS-2) was performed immediately and a third (LUS-3) was done 2 h later on the same respiratory support. The primary outcome was to compare LUS scores in the different timelines. Second outcomes were to evaluate the level of respiratory distress and oxygenation were evaluated with SpO2 /fraction of inspired oxygen (FiO2 ) ratio (S/F ratio), FiO2  ratio, respiratory rate, and blood gas analysis which were analyzed during the LUS-1 and the LUS-3. To evaluate newborn discomfort, patients were evaluated with Crying Requires oxygen Increased vital signs Expression Sleep (CRIES) scale.

RESULTS

Forty neonates were enrolled. Fifty percent were female (n = 20), median gestational age was 38 + 4 (interquartile range [IQR]: 37 + 5-39 + 4) with a median weight of 3155 g (IQR: 2637-3532). Duration of non invasive ventilation support was 72 h (IQR: 54-96). None of the patients required surfactant therapy or mechanical ventilation. LUS scores were no different between LUS-1 9 (IQR: 8.3-10) and LUS-2 9 (IQR: 8.3-10) (p = 0.675) but there were differences between LUS-1 and LUS-3 7 (IQR: 6.3-8.5) (p = 0.036). There was an improvement in the oxygen parameters, respiratory rate, and CO2 between LUS-1 and LUS-3 (p < 0.001). There were no changes in the CRIES scale.

CONCLUSIONS

There is an improvement in clinical and laboratory parameters after the increasing of respiratory support in newborns with noninvasive ventilation. We observe a correlation with an improvement in the assessment of lung aeration were evaluated with LUS score.

Imaging the acute respiratory distress syndrome: past, present and future

In patients with the acute respiratory distress syndrome (ARDS), lung imaging is a fundamental tool in the study of the morphological and mechanistic features of the lungs. Chest computed tomography studies led to major advances in the understanding of ARDS physiology. They allowed the in vivo study of the syndrome's lung features in relation with its impact on respiratory physiology and physiology, but also explored the lungs' response to mechanical ventilation, be it alveolar recruitment or ventilator-induced lung injuries. Coupled with positron emission tomography, morphological findings were put in relation with ventilation, perfusion or acute lung inflammation. Lung imaging has always been central in the care of patients with ARDS, with modern point-of-care tools such as electrical impedance tomography or lung ultrasounds guiding clinical reasoning beyond macro-respiratory mechanics. Finally, artificial intelligence and machine learning now assist imaging post-processing software, which allows real-time analysis of quantitative parameters that describe the syndrome's complexity. This narrative review aims to draw a didactic and comprehensive picture of how modern imaging techniques improved our understanding of the syndrome, and have the potential to help the clinician guide ventilatory treatment and refine patient prognostication.

Role of lung ultrasound patterns in monitoring coronavirus disease 2019 pneumonia and acute respiratory distress syndrome in children

BACKGROUND

During the coronavirus disease 2019 (COVID-19) pandemic, lung ultrasonography (US) has been gaining importance in pediatric intensive care and emergency settings for the screening, diagnosis, and monitoring of pulmonary pathology.

PURPOSE

To describe the pattern of lung US changes in patients with COVID-19 pneumonia and its potential role in monitoring ventilated patients.

METHODS

This prospective observational study included children aged 1 month to 12 years with a confirmed diagnosis of COVID-19. Lung US was performed using a high-frequency linear probe (5-12 MHz) in all children with moderate/severe respiratory symptoms within 24 hours of admission and then daily until the patient required oxygen therapy. Lung involvement severity was assessed using lung US scores, while lung aeration improvement or deterioration was measured using lung ultrasound reaeration scores (LUSReS).

RESULTS

Of 85 children with moderate to severe disease, 54 with pulmonary disease were included. Of them, 50 (92.5%) had an interstitial pattern, followed by pleural line abnormalities in 44 (81.5%), reduced or absent lung sliding in 31 (57.4%), and consolidation in 28 (51.8%). A significantly higher lung US score (median, 18; interquartile range [IQR], 11-22) was observed in ventilated versus nonventilated patients (median, 9; IQR, 6-11). LUSReS improvement after positive end-expiratory pressure titration was positively correlated with improved dynamic lung compliance and oxygenation indices and negatively correlated with the requirement for driving pressure. Successful weaning could be predicted with 100% specificity if loss of LUSReS ≤ 5.

CONCLUSION

Interstitial syndrome, fragmented pleural line, and subpleural microconsolidation were the most prevalent lung US findings in children with COVID-19 pneumonia. Thus, lung US may have the ability to monitor changes in lung aeration caused by mechanical ventilation and predict its successful weaning in children with COVID-19.

Lung Ultrasound Findings Associated With COVID-19 ARDS, ICU Admission, and All-Cause Mortality

BACKGROUND

As lung ultrasound (LUS) has emerged as a diagnostic tool in patients with COVID-19, we sought to investigate the association between LUS findings and the composite in-hospital outcome of ARDS incidence, ICU admission, and all-cause mortality.

METHODS

In this prospective, multi-center, observational study, adults with laboratory-confirmed SARS-CoV-2 infection were enrolled from non-ICU in-patient units. Subjects underwent an LUS evaluating a total of 8 zones. Images were analyzed off-line, blinded to clinical variables and outcomes. A LUS score was developed to integrate LUS findings: ≥ 3 B-lines corresponded to a score of 1, confluent B-lines to a score of 2, and subpleural or lobar consolidation to a score of 3. The total LUS score ranged from 0-24 per subject.

RESULTS

Among 215 enrolled subjects, 168 with LUS data and no current signs of ARDS or ICU admission (mean age 59 y, 56% male) were included. One hundred thirty-six (81%) subjects had pathologic LUS findings in ≥ 1 zone (≥ 3 B-lines, confluent B-lines, or consolidations). Markers of disease severity at baseline were higher in subjects with the composite outcome (n = 31, 18%), including higher median C-reactive protein (90 mg/L vs 55, P < .001) and procalcitonin levels (0.35 μg/L vs 0.13, P = .033) and higher supplemental oxygen requirements (median 4 L/min vs 2, P = .001). However, LUS findings and score did not differ significantly between subjects with the composite outcome and those without, and were not associated with outcomes in unadjusted and adjusted logistic regression analyses.

CONCLUSIONS

Pathologic findings on LUS were common a median of 3 d after admission in this cohort of non-ICU hospitalized subjects with COVID-19 and did not differ among subjects who experienced the composite outcome of incident ARDS, ICU admission, and all-cause mortality compared to subjects who did not. These findings should be confirmed in future investigations. The study is registered at Clinicaltrials.gov (NCT04377035).

Lung ultrasound and the role of lung aeration score in patients with acute respiratory distress syndrome on extracorporeal membrane oxygenation

OBJECTIVE

This was a pilot study to determine the utility of daily lung ultrasound (LUS) in patients requiring veno-venous extracorporeal membrane oxygenation (VV-ECMO) for acute respiratory distress syndrome (ARDS).

DESIGN

This was a prospective, observational study.

SETTING

The study took place in the intensive care unit at Royal Papworth Hospital in Cambridge, UK.

PARTICIPANTS

We recruited adult patients receiving VV-ECMO for ARDS.

INTERVENTIONS

All patients received a lung computed tomography (CT) scan and LUS on admission. Bedside chest radiography (CXR) and LUS were done on a daily basis until patients were decannulated.

MEASUREMENTS AND MAIN RESULTS

Daily LUS aeration scores were calculated according to the appearance of four defined patterns. An independent radiologist calculated corresponding scores for CT and CXR, retrospectively. These were checked for correlation with LUS aeration scores. There were statistically significant correlations between LUS versus CT (r = 0.868, p = 0.002) and LUS versus CXR (r = 0.498, p = 0.018) with good agreement and no evidence of proportional bias. LUS was able to detect 13.5% of pleural effusions and 54.2% of pneumothorax that were not picked up on CXR.In most of the patients who were weaned off VV-ECMO, a progressive reduction of LUS aeration scores corresponding to lung re-aeration was observed.

CONCLUSIONS

LUS correlated with findings on CT and CXR for quantifying lung aeration and the clinical presentation of patients. LUS also picked up more pleural effusions and pneumothorax than CXR. Together with traditional imaging techniques, the routine use of LUS should be considered for this patient group.

Transoesophageal Ultrasound Assessment of Lung Aeration in Patients With Acute Respiratory Distress Syndrome

Introduction: The effect of positive end-expiratory pressure (PEEP) depends closely on the potential for lung recruitment. Bedside assessment of lung recruitability is crucial for personalized lung-protective mechanical ventilation in acute respiratory distress syndrome (ARDS) patients. Methods: We developed a transoesophageal lung ultrasound (TE-LUS) method in which a quantitative (computer-assisted) grayscale determination served as a guide to PEEP-induced lung recruitment. The method is based on the following hypothesis: when the PEEP increases, inflation of the recruited alveoli leads to significant changes in the air/water ratio. Normally ventilated areas are hypoechoic because the ultrasound waves are weakly reflected while poorly aerated areas or non-aerated areas are hyperechoic. We calculated the TE-LUS re-aeration score (RAS) as the ratio of the mean gray scale level at low PEEP to that value at high PEEP for the lower and upper lobes. A RAS > 1 indicated an increase in ventilated area. We used this new method to detect changes in ventilation in patients with a low (<0.5) vs. high (≥0.5) recruitment-to-inflation (R/I) ratio (i.e., the ratio between the recruited lung compliance and the respiratory system compliance at low PEEP). Results: We included 30 patients with moderate-to-severe ARDS. In patients with a high R/I ratio, the TE-LUS RAS was significantly higher in the lower lobes than in the upper lobes (1.20 [1.12-1.63] vs. 1.05 [0.89-1.38]; p = 0.05). Likewise, the TE-LUS RAS in the lower lobes was significantly higher in the high R/I group than in the low R/I group (1.20 [1.12-1.63] vs. 1.07 [1.00-1.20]; p = 0.04). Conclusion: The increase in PEEP induces a substantial gain in the ventilation detected by TE-LUS of poorly or non-aerated lower lobes (dependent lung regions), especially in patients with a high R/I ratio.

Interstitial lung opacities in patients with severe COVID-19 pneumonia by bedside high-resolution ultrasound in association to CO2 retention

BACKGROUND

Coronavirus disease 2019 (COVID-19) can cause acute respiratory distress syndrome (ARDS).

OBJECTIVE

This single centre cross-section study aimed to grade the severity of pneumonia by bed-side lung ultrasound (LUS).

METHODS

A scoring system discriminates 5 levels of lung opacities: A-lines (0 points),≥3 B-line (1 point), coalescent B-lines (2 points), marked pleural disruptions (3 points), consolidations (4 points). LUS (convex 1-5 MHz probe) was performed at 6 defined regions for each hemithorax either in supine or prone position. A lung aeration score (LAS, maximum 4 points) was allocated for each patient by calculating the arithmetic mean of the examined lung areas. Score levels were correlated with ventilation parameters and laboratory markers.

RESULTS

LAS of 20 patients with ARDS reached from 2.58 to 3.83 and was highest in the lateral right lobe (Mean 3.67). Ferritin levels (Mean 1885μg/l; r = 0.467; p = 0.051) showed moderate correlation in spearman roh calculation. PaCO2 level (Mean 46.75 mmHg; r = 0.632; p = 0.005) correlated significantly with LAS, while duration of ventilation, Horovitz index, CRP, LDH and IL-6 did not.

CONCUSIONS

The proposed LAS describes severity of lung opacities in COVID-19 patients and correlates with CO2 retention in patients with ARDS.

Deep Learning for Classification and Localization of COVID-19 Markers in Point-of-Care Lung Ultrasound

Deep learning (DL) has proved successful in medical imaging and, in the wake of the recent COVID-19 pandemic, some works have started to investigate DL-based solutions for the assisted diagnosis of lung diseases. While existing works focus on CT scans, this paper studies the application of DL techniques for the analysis of lung ultrasonography (LUS) images. Specifically, we present a novel fully-annotated dataset of LUS images collected from several Italian hospitals, with labels indicating the degree of disease severity at a frame-level, video-level, and pixel-level (segmentation masks). Leveraging these data, we introduce several deep models that address relevant tasks for the automatic analysis of LUS images. In particular, we present a novel deep network, derived from Spatial Transformer Networks, which simultaneously predicts the disease severity score associated to a input frame and provides localization of pathological artefacts in a weakly-supervised way. Furthermore, we introduce a new method based on uninorms for effective frame score aggregation at a video-level. Finally, we benchmark state of the art deep models for estimating pixel-level segmentations of COVID-19 imaging biomarkers. Experiments on the proposed dataset demonstrate satisfactory results on all the considered tasks, paving the way to future research on DL for the assisted diagnosis of COVID-19 from LUS data.

Mechanical ventilation weaning issues can be counted on the fingers of just one hand: part 2

Assessing heart and diaphragm function constitutes only one of the steps to consider along the weaning path. In this second part of the review, we will deal with the more systematic evaluation of the pulmonary parenchyma—often implicated in the genesis of respiratory failure. We will also consider the other possible causes of weaning failure that lie beyond the cardio-pulmonary-diaphragmatic system. Finally, we will take a moment to consider the remaining unsolved problems arising from mechanical ventilation and describe the so-called protective approach to parenchyma and diaphragm ventilation.

Lung Ultrasound for the Diagnosis and Management of Acute Respiratory Failure

For critically ill patients with acute respiratory failure (ARF), lung ultrasound (LUS) has emerged as an indispensable tool to facilitate diagnosis and rapid therapeutic management. In ARF, there is now evidence to support the use of LUS to diagnose pneumothorax, acute respiratory distress syndrome, cardiogenic pulmonary edema, pneumonia, and acute pulmonary embolism. In addition, the utility of LUS has expanded in recent years to aid in the ongoing management of critically ill patients with ARF, providing guidance in volume status and fluid administration, titration of positive end-expiratory pressure, and ventilator liberation. The aims of this review are to examine the basic foundational concepts regarding the performance and interpretation of LUS, and to appraise the current literature supporting the use of this technique in the diagnosis and continued management of patients with ARF.

Imaging of Diffuse Lung Disease in the Intensive Care Unit Patient

There is a wide variety of causes of diffuse lung disease in the intensive care unit patient, of which adult respiratory distress syndrome is the commonest clinical consideration. Plain radiography, computed tomography, and ultrasound can be used synergistically to evaluate patients with diffuse lung disease and respiratory impairment. Imaging is not limited to characterization of the cause of diffuse lung disease but also aids in monitoring its evolution and in ventilator setting management.

ERS statement on chest imaging in acute respiratory failure

Chest imaging in patients with acute respiratory failure plays an important role in diagnosing, monitoring and assessing the underlying disease. The available modalities range from plain chest X-ray to computed tomography, lung ultrasound, electrical impedance tomography and positron emission tomography. Surprisingly, there are presently no clear-cut recommendations for critical care physicians regarding indications for and limitations of these different techniques.The purpose of the present European Respiratory Society (ERS) statement is to provide physicians with a comprehensive clinical review of chest imaging techniques for the assessment of patients with acute respiratory failure, based on the scientific evidence as identified by systematic searches. For each of these imaging techniques, the panel evaluated the following items: possible indications, technical aspects, qualitative and quantitative analysis of lung morphology and the potential interplay with mechanical ventilation. A systematic search of the literature was performed from inception to September 2018. A first search provided 1833 references. After evaluating the full text and discussion among the committee, 135 references were used to prepare the current statement.These chest imaging techniques allow a better assessment and understanding of the pathogenesis and pathophysiology of patients with acute respiratory failure, but have different indications and can provide additional information to each other.

Imaging the Injured Lung: Mechanisms of Action and Clinical Use

Acute respiratory distress syndrome (ARDS) consists of acute hypoxemic respiratory failure characterized by massive and heterogeneously distributed loss of lung aeration caused by diffuse inflammation and edema present in interstitial and alveolar spaces. It is defined by consensus criteria, which include diffuse infiltrates on chest imaging-either plain radiography or computed tomography. This review will summarize how imaging sciences can inform modern respiratory management of ARDS and continue to increase the understanding of the acutely injured lung. This review also describes newer imaging methodologies that are likely to inform future clinical decision-making and potentially improve outcome. For each imaging modality, this review systematically describes the underlying principles, technology involved, measurements obtained, insights gained by the technique, emerging approaches, limitations, and future developments. Finally, integrated approaches are considered whereby multimodal imaging may impact management of ARDS.

Effect of ultrafiltration on extravascular lung water assessed by lung ultrasound in children undergoing cardiac surgery: a randomized prospective study

Background

Increased lung water and the resultant atelectasis are significant pulmonary complications after cardiopulmonary bypass (CPB) in children undergoing cardiac surgery; these complications are observed after CPB than after anaesthesia alone. Ultrafiltration has been shown to decrease total body water and postoperative blood loss and improve the alveolar to arterial oxygen gradient and pulmonary compliance. This study investigated whether conventional ultrafiltration during CPB in paediatric heart surgeries influences post-bypass extravascular lung water (EVLW) assessed by lung ultrasound (LUS).

Methods

This randomized controlled study included 60 patients with congenital heart disease (ASA II-III), aged 1 to 48 months, with a body weight > 3 kg. Conventional ultrafiltration targeting a haematocrit (HCT) level of 28% was performed on the ultrafiltration group, while the control group did not receive ultrafiltration. LUS scores were recorded at baseline and at the end of surgery. The PaO2/FiO2 ratio (arterial oxygen tension divided by the fraction of inspired oxygen), urine output, and haemodynamic parameters were also recorded.

Results

LUS scores were comparable between the two groups both at baseline (p = 0.92) and at the end of surgery (p = 0.95); however, within the same group, the scores at the end of surgery significantly differed from their baseline values in both the ultrafiltration (p = 0.01) and non-ultrafiltration groups (p = 0.02).

The baseline PaO2/FiO2 ratio was comparable between both groups. at the end of surgery, The PaO2/FiO2 ratio increased in the ultrafiltration group compared to that in the non-ultrafiltration group, albeit insignificant (p = 0.16). no correlation between the PaO2/FiO2 ratio and LUS score was found at baseline (r = − 0.21, p = 0.31). On the other hand, post-surgical measurements were negatively correlated (r = − 0.41, p = 0.045).

Conclusion

Conventional ultrafiltration did not alter the EVLW when assessed by LUS and oxygenation state. Similarly, ultrafiltration did not affect the urea and creatinine levels, intensive care unit (ICU) stays, ventilation days, or mortality.

Trial registration

Clinicaltrials.gov Identifier: NCT03146143 registered on 29-April-2017.

Lung Ultrasonography for Assessing Lung Aeration in Acute Respiratory Distress Syndrome: A Narrative Review

Acute respiratory distress syndrome (ARDS) constitutes a high burden for intensive care units. Although several methods are proposed to monitor aeration in ARDS, availability, costs, simplicity, and hazards (eg, ionizing radiation) limit the use of many of them at patients' bedsides. Given the widespread use of lung ultrasonography (US) in intensive care units, research is growing regarding its use to monitor aeration in patients with ARDS. We reviewed the actual role of lung US in ARDS and its potential impact in practice. Lung US can be readily used for assessing aeration, although, as a main limitation, a normal lung cannot be distinguished from hyperinflation. Additionally, an improvement in aeration by lung US does not always correlate with an increase in oxygenation. Lung US can be considered the main imaging method for monitoring aeration in ARDS, but in view of its limitations, it should not be used in isolation. Further studies are needed to validate lung US in large ARDS populations.

Utility of bedside lung ultrasound for assessment of lung recruitment in a case of acute respiratory distress syndrome

Lung recruitment maneuvers are rescue measures commonly used to improve oxygenation in severely hypoxemic patients with acute respiratory distress syndrome (ARDS), who fail to improve on standard treatment. After recruitment, appropriate level of positive end-expiratory pressure (PEEP) is applied to prevent alveolar de-recruitment during expiration. Computed tomography scan of thorax and quasi-static pressure-volume curves have played a pivotal role are important in the assessment of recruitment, but they have several limitations. Lung ultrasound (LUS), which is now easily available in nearly every Intensive Care Unit, could be an attractive alternative method for assessing lung recruitment. It is noninvasive, easily repeatable and is devoid of radiation hazards. We are presenting a case of 24-year-old female patient with moderate ARDS in whom bedside LUS was successfully used into assessing lung recruitment as well as into determining the appropriate level of PEEP.

Usefulness of ultrasound in the management of acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a life-threatening disease. Different imaging techniques have been used to diagnose and guide the ventilatory management of patients with ARDS. Chest ultrasound is a reliable tool to identify interstitial syndrome, lung consolidation, lung collapse, and pleural effusion. In addition, echocardiography is essential in the diagnosis of diastolic left ventricle dysfunction and the estimation of elevated ventricle filling pressures, which is necessary before diagnosing ARDS. Therefore, combining chest and heart ultrasound assessment is useful to diagnose ARDS and guide the ventilatory management of the disease. Available data in the literature suggest that protocol-based approaches should be implemented for the purposes of diagnosis and management.

Lung ultrasound: Predictor of acute respiratory distress syndrome in intensive care unit patients

PURPOSE

The purpose of the study was to review and summarize current literature concerning the validation and application of lung ultrasound (LUS) in critically ill patients with acute respiratory distress syndrome (ARDS).

MATERIALS AND METHODS

An extensive literature search was conducted using PubMed, Cochrane Review, Google Scholar, and Ohio State University Link based on the question if LUS should be considered a reliable investigational technique for ARDS diagnosis, treatment, and prognosis in pediatric and adult population.

RESULTS

LUS has been successfully validated for facilitating early diagnosis and diagnosis of simultaneous lung conditions, predicting lung recruitment treatment effect, and evaluating the prognosis in ARDS patients. Whether lung US is a useful tool in the prediction of prone position and oxygenation response in patients with ARDS is conflicting.

CONCLUSIONS

LUS is a noninvasive, radiation-free, cheap, and easy to perform tool for critically ill patients with ARDS and might be a promising technique used in the Intensive Care Unit for ARDS management.

Lung Ultrasonography to Diagnose Transient Tachypnea of the Newborn

BACKGROUND

This study explored the sensitivity and specificity of ultrasound for diagnosing transient tachypnea of the newborn (TTN).

METHODS

Ultrasound was performed by one export. Patients were placed in a supine, lateral recumbent, or prone position. The probe was placed perpendicular or parallel to the ribs, and each region of the lung was scanned. The scan results were compared with conventional chest radiographic results.

RESULTS

A total of 1,358 infants were included in this study. We identified 412 cases without pulmonary diseases, 228 TTN cases, 358 respiratory distress syndrome (RDS) cases, 85 meconium aspiration syndrome (MAS) cases, 215 infectious pneumonia cases, and 60 other cases. The primary ultrasonic characteristic of TTN was pulmonary edema. "White lung" or a "compact B-line" were only observed in severe cases, whereas TTN primarily presented as pulmonary interstitial syndrome or "double lung point." Furthermore, double lung point could appear during the recovery period of severe TTN or RDS, MAS, and pneumonia. Lung consolidation with air bronchograms was not observed in TTN patients. The results showed that white lung or a compact B-line exhibited a sensitivity of 33.8% and a specificity of 91.3% in diagnosing TTN, whereas double lung point exhibited a sensitivity of 45.6% and a specificity of 94.8% in diagnosing severe TTN.

CONCLUSIONS

Pulmonary edema, alveolar-interstitial syndrome, double lung point, white lung, and compact B-line are the primary ultrasound characteristics of TTN. Ultrasonic diagnosis of TTN based on these findings is accurate and reliable. TTN can be ruled out in the presence of lung consolidation with air bronchograms.

Can lung ultrasonography predict prone positioning response in acute respiratory distress syndrome patients?

PURPOSE

The purpose was to assess whether lung ultrasonography (L-US) is a useful tool in prediction of prone positioning (PP) oxygenation response in patients with acute respiratory distress syndrome (ARDS).

METHODS

In a prospective study, 19 ARDS patients were included for assessment of PP oxygenation response. The latter was assessed for at least 12 hours 6 different ultrasonography windows were performed on each hemithorax before prone (H0, H2, H12 before return to supine and at H14 (2 hours after return to supine). Patients were classified into 2 groups (responders / non responders) according their oxygenation response to PP. Ultrasonography videos were blindly evaluated by 3 expert clinicians to classify lung regions as "normal", "moderate loss of aeration," "severe loss of aeration," or "lung consolidation." Oxygenation parameters were collected at H0, H2, and H14.

RESULTS

Association of each lung region aspect to PP oxygenation response was compared between the 2 groups. The normal aspect of the anterobasal regions was significantly associated with the oxygenation response (P = .0436), with a positive predictive value equal to or near 100%.

DISCUSSION

Our results demonstrated that a simple and short L-US examination could be a useful tool in prediction of PP oxygenation response in ARDS patients. A normal L-US pattern of both anterobasal lung regions in supine position may predict a significant PaO2/FIO2 ratio improvement.

Use of Lung Ultrasound to Assess the Efficacy of an Alveolar Recruitment Maneuver in Rabbits With Acute Respiratory Distress Syndrome

OBJECTIVES

To investigate the application of lung ultrasound (US) in the evaluation and implementation of alveolar recruitment maneuvers in acute respiratory distress syndrome (ARDS).

METHODS

Twelve rabbits with saline lavage-induced lung injury were randomly divided into 2 groups: one with alveolar recruitment guided by lung US and the other with alveolar recruitment guided by maximal oxygenation. Recruitment maneuvers were applied according to a stepwise incremental positive end-expiratory pressure method in both groups. In the oxygenation group, a sum of the partial pressures of oxygen and carbon dioxide exceeding 400 mm Hg was used to define adequate recruitment. In the lung US group, a new protocol for reaeration in US-guided lung recruitment was used to guide treatment. Evaluation by lung US, respiratory mechanical parameters, the Smith pathologic score (Crit Care Med 1997; 25:1888-1897), and wet-to-dry ratio were compared between the groups.

RESULTS

Opening pressure was significantly higher in the lung US group (mean ± SD, 23.4 ± 3.4 cm H2O) than the oxygenation group (18.7 ± 2.1 cm H2O; P < .05). The reaeration score in the lung US group significantly increased during alveolar recruitment (6.5 ± 1.6 points at baseline versus 13.8 ± 3.0 points after completion; P < .05). Lung compliance, dead space shunts, the Smith pathologic score, and tissue wet-to-dry ratio, however, were not significantly different between the groups.

CONCLUSIONS

Lung US is an effective means of evaluating and guiding alveolar recruitment in ARDS. Compared with the maximal oxygenation-guided method, the protocol for reaeration in US-guided lung recruitment achieved a higher opening pressure, resulted in greater improvements in lung aeration, and substantially reduced lung heterogeneity in ARDS.

Application of Lung Ultrasonography in the Diagnosis of Childhood Lung Diseases

In this paper, we focus on the characteristics of LUS in diagnosing childhood pulmonary disease. LUS is convenient, noninvasive, and free of radiation. It helps in the differentiation of lung diseases. Therefore, LUS has the potential to become a reference instrument for bedside dynamic respiratory monitoring. We hope that this review will help clinicians become acquainted with LUS and will accelerate the extensive application of LUS in children.

[Lung ultrasonography for the diagnosis of pneumonia in pregnant women with blood system tumors]

AIM

To estimate the informative value of ultrasonography (USG) in the diagnosis of lung injuries in pregnant women with blood system tumors.

SUBJECTS AND METHODS

Lung ultrasound was performed in 5 pregnant patients with blood cancers. The women's age was 29-38 years; gestational age was 14-33 weeks. Four women had different types of acute leukemia; one had primary mediastinal large B-cell lymphoma. All the women received chemotherapy for blood cancer. When there were signs of lung injury, USG was conducted, the results of which necessitated therapy or bronchoalveolar lavage (BAL).

RESULTS

Three patients developed acute respiratory failure; 2 of them required noninvasive ventilation. Based on the detection of consolidation with a dynamic air bronchogram and pleural effusion, the authors diagnosed bilateral pneumonia and alveolar-interstitial syndrome in 1 patient, right-sided pneumonia in 1, left-sided one in 1, and transfusion-related pulmonary edema in 1. Lung ultrasound did not verify the diagnosis of pneumonia in 1 patient. According to USG data, BAL procedures were performed in 2 patients; one of them was diagnosed as having Pneumocystis pneumonia; the other was found to have no pathogens in lavage fluid. Treatment resulted in clinical improvements and normalization of the lung ultrasound pattern in all the pregnant women. Later on, 4 women delivered via cesarean section done at 32-34 weeks' gestation and gave birth to healthy babies. One patient died from infectious complications after chemotherapy.

CONCLUSION

Lung sound may be used to diagnose lung injury in pregnant women with blood cancers.

Ultrasound for "lung monitoring" of ventilated patients

In the intensive care unit, patient lung ultrasound provides accurate information on lung morphology with diagnostic and therapeutic relevance. It enables clinicians easy, rapid, and reliable evaluation of lung aeration and its variations at the bedside.

Supplemental Digital Content is available in the text.

[Basic lung ultrasound. Part 2. Parenchymal diseases]

In this second part, an analysis is made of the pathology of lung parenchyma. This text is structured into different sections, including the study of atelectasias, pneumonia and abscess, interstitial/alveolar or Blines patterns, and finally an analysis is made of pulmonary embolism. With this second part, the basic knowledge to develop lung ultrasound in the anesthesia department has been presented.

Overview of current lung imaging in acute respiratory distress syndrome

Imaging plays a key role in the diagnosis and follow-up of acute respiratory distress syndrome (ARDS). Chest radiography, bedside lung ultrasonography and computed tomography scans can provide useful information for the management of patients and detection of prognostic factors. However, imaging findings are not specific and several possible differential diagnoses should be taken into account. Herein we will review the role of radiological techniques in ARDS, highlight the plain radiological and computed tomography findings according to the pathological stage of the disease (exudative, inflammatory and fibroproliferative), and summarise the main points for the differential diagnosis with cardiogenic oedema, which is still challenging in the acute stage.

Diagnosis of neonatal transient tachypnea and its differentiation from respiratory distress syndrome using lung ultrasound

Transient tachypnea of the newborn (TTN) is one of the most common causes of perinatal dyspnea and is traditionally diagnosed by chest x-ray. This study aimed to explore the diagnostic value of lung ultrasonography (LUS) for TTN as well as differentiate it from respiratory distress syndrome (RDS) by using LUS. From January 2013 to February 2014, 60 infants who were diagnosed with TTN based on medical history, clinical manifestations, arterial blood gas analysis, and chest radiography were recruited to the study group. During the same period, 40 hospitalized neonates with nonlung diseases and 20 patients with RDS were recruited to the control group. In a quiet state, infants were placed in the supine, lateral, or prone position for the examination. Each lung of every infant was divided into 3 regions: the anterior, lateral, and posterior regions as bordered by the anterior axillary and posterior axillary lines. The probe was placed perpendicular to the ribs. Each region of both the lungs was carefully scanned.The common ultrasonographic manifestations of TTN were double-lung point (DLP), interstitial syndromes or white lungs, pleural line abnormalities, and A-line disappearance. A small number of infants (20%) with TTN exhibited pleural effusions, whereas the main ultrasonographic manifestation of RDS was lung consolidation with air bronchograms, which does not occur in TTN. The sensitivity and specificity of DLP for the diagnosis of TTN were 76.7% and 100%, respectively. LUS can accurately and reliably diagnose TTN. The DLP and lung consolidation possess great value in the diagnosis and differential diagnosis of TTN with RDS. Thus, we believe that LUS can be widely used in neonatal intensive care units.

Clinical review: Lung imaging in acute respiratory distress syndrome patients--an update

Over the past 30 years lung imaging has greatly contributed to the current understanding of the pathophysiology and the management of acute respiratory distress syndrome (ARDS). In the past few years, in addition to chest X-ray and lung computed tomography, newer functional lung imaging techniques, such as lung ultrasound, positron emission tomography, electrical impedance tomography and magnetic resonance, have been gaining a role as diagnostic tools to optimize lung assessment and ventilator management in ARDS patients. Here we provide an updated clinical review of lung imaging in ARDS over the past few years to offer an overview of the literature on the available imaging techniques from a clinical perspective.

Positive end-expiratory pressure lung recruitment: comparison between lower inflection point and ultrasound assessment

BACKGROUND

Maintenance of the open lung alveoli in the expiration on mechanical ventilation in acute lung injury/acute respiratory distress syndrome (ALI/ARDS) remains challenging despite advances in lung imaging. The inspiratory lower inflection point (LIP) on the ventilator pressure-volume (P-V) curve estimates the required end-expiratory pressure for recruitment of alveolar consolidation. Alternatively, the end-expiratory pressure for recruitment of crater-like subpleural alveolar consolidation could be simply followed with ultrasound. These two methods for setting the ventilators positive end-expiratory pressure (PEEP) were compared.

METHODS

The observational study in surgical/neurosurgical intensive care between October 2009 and November 2011 included 17 deeply sedated or relaxed patients. LIP was measured with continuous low-flow method, as a pressure in cmH(2)O. Expiratory levelling between lower border of subpleural consolidation and adjacent pleural line, which means lung recruitment, was followed with linear ultrasound probe. PEEP in cmH(2)O at which the levelling occurs was compared with LIP pressure.

RESULTS

LIP pressure never exceeds the PEEP for recruitment of subpleural consolidations followed with ultrasound. A significant correlation (r = 0.839; p < 0.05) was found between two methods.

CONCLUSIONS

In this study, positive end-expiratory pressures for recruitment of subpleural consolidations followed by ultrasound always exceed the pressures measured with LIP. Respecting this, ultrasound method could be the guide for PEEP lung recruitment.

Lung imaging for titration of mechanical ventilation

PURPOSE OF REVIEW

Computed tomography (CT) has fostered pivotal advancements in the understanding of acute lung injury/acute respiratory distress syndrome and ventilator-induced lung injury. Apart from CT-based studies, the past years have seen fascinating work using positron emission tomography, electrical impedance tomography and lung ultrasound as diagnostic tools to optimize mechanical ventilation. This review aims to present the major findings of recent studies on lung imaging.

RECENT FINDINGS

Patients presenting with a focal loss of aeration on CT may not be suitable candidates for recruitment maneuvers and high levels of positive end-expiratory pressure (PEEP) in supine position. PET/CT has provided valuable insights into the inflammatory response of the lung. Electrical impedance tomography has been used to assess lung recruitability and to titrate PEEP. Finally, lung ultrasound has proven to be reliable diagnostic tool for assessing PEEP-induced recruitment.

SUMMARY

Whereas quantitative CT remains the gold standard to assess lung morphology, recruitment and hyperinflation of lung tissue at different inflation pressures, EIT and LUS have emerged as valuable, radiation-free, noninvasive bedside lung imaging tools that should be used together with global parameters like lung mechanics and gas exchange to acquire additional information on recruitability and ventilation distribution.

Sonographic lobe localization of alveolar-interstitial syndrome in the critically ill

Introduction. Fast and accurate diagnosis of alveolar-interstitial syndrome is of major importance in the critically ill. We evaluated the utility of lung ultrasound (US) in detecting and localizing alveolar-interstitial syndrome in respective pulmonary lobes as compared to computed tomography scans (CT). Methods. One hundred and seven critically ill patients participated in the study. The presence of diffuse comet-tail artifacts was considered a sign of alveolar-interstitial syndrome. We designated lobar reflections along intercostal spaces and surface lines by means of sonoanatomy in an effort to accurately localize lung pathology. Each sonographic finding was thereafter grouped into the respective lobe. Results. From 107 patients, 77 were finally included in the analysis (42 males with mean age = 61 ± 17 years, APACHE II score = 17.6 ± 6.4, and lung injury score = 1.0 ± 0.7). US exhibited high sensitivity and specificity values (ranging from over 80% for the lower lung fields up to over 90% for the upper lung fields) and considerable consistency in the diagnosis and localization of alveolar-interstitial syndrome. Conclusions. US is a reliable, bedside method for accurate detection and localization of alveolar-interstitial syndrome in the critically ill.

Year in review 2011: Critical Care - respirology

Management of acute respiratory failure is an important component of intensive care. In this review, we analyze 21 original research articles published last year in Critical Care in the field of respiratory and critical care medicine. The articles are summarized according to the following topic categories: acute respiratory distress syndrome, mechanical ventilation, adjunctive therapies, and pneumonia.