Lung ultrasound: a useful tool in the assessment of the dyspnoeic patient in the emergency department. Fact or fiction?

Thoracic ultrasound use in hospitalized and ambulatory adult patients: a quantitative picture

INTRODUCTION AND OBJECTIVES

Thoracic ultrasound (TUS) has been established as a powerful diagnostic and monitoring tool in the Intensive Care Unit (ICU). However, studies outside the critical care setting are scarce. The aim of this study was to investigate the value of TUS for hospitalized or ambulatory community patients.

MATERIALS AND METHODS

This was a retrospective study conducted from 2016 to 2020 in the TUS clinic at Heraklion University Hospital. TUS examination was performed using a standard ultrasound machine (EUB HITACHI 8500), and a high-frequency microconvex probe (5-8 MHz). Patients had been referred by their primary physician to address a range of different questions. The various respiratory system entities were characterised according to internationally established criteria.

RESULTS

762 TUS studies were performed on 526 patients due to underlying malignancy (n = 376), unexplained symptoms/signs (n = 53), pregnancy related issues (n = 42), evaluation of abnormal findings in X-ray (n = 165), recent surgery/trauma (n = 23), recent onset respiratory failure (n = 12), acute respiratory infection (n = 66) and underlying non-malignant disease (n = 25). Pleural effusion was the commonest pathologic entity (n = 610), followed by consolidation (n = 269), diaphragmatic dysfunction/paradox (n = 174) and interstitial syndrome (n = 53). Discrepancies between chest X-ray and ultrasonographic findings were demonstrated in 96 cases. The TUS findings guided invasive therapeutic management in 448 cases and non-invasive management in 43 cases, while follow-up monitoring was decided in 271 cases.

CONCLUSIONS

This study showed that TUS can identify the most common respiratory pathologic entities encountered in hospitalized and community ambulatory patients, and is especially useful in guiding the decision making process in a diverse group of patients.

Interoperator Reliability of Lung Ultrasound during the COVID-19 Pandemic

AIM

 Lung ultrasound (LUS) is a reliable, radiation-free, and bedside imaging technique used to assess several pulmonary diseases. Although COVID-19 is diagnosed with a nasopharyngeal swab, detection of pulmonary involvement is crucial for safe patient discharge. Computed tomography (CT) is currently the gold standard. To treat paucisymptomatic patients, we have implemented a "fast track" pathway in our emergency department, using LUS as a valid alternative. Minimal data is available in the literature about interobserver reliability and the level of expertise needed to perform a reliable examination. Our aim was to assess these.

MATERIALS AND METHODS

 This was a single-center prospective study. We enrolled 96 patients. 12 lung areas were explored in each patient with a semiquantitative assessment of pulmonary aeration loss in order to obtain the LUS score. Scans were performed by two different operators, an expert and a novice, who were blinded to their colleague's results.

RESULTS

 96 patients were enrolled. The intraclass correlation coefficient (ICC) showed excellent agreement between the expert and the novice operator (ICC 0.975; 0.962-0.983); demographic features (age, sex, and chronic pulmonary disease) did not influence the reproducibility of the method. The ICC was 0.973 (0.950-0.986) in males, 0.976 (0.959-0.986) in females; 0.965 (0.940-0.980) in younger patients (≤ 46 yrs), and 0.973 (0.952-0.985) in older (> 46 yrs) patients. The ICC was 0.967 (0.882-0.991) in patients with pulmonary disease and 0.975 (0.962-0.984) in the other patients. The learning curve showed an increase in interobserver agreement.

CONCLUSION

 Our results confirm the feasibility and reproducibility of the method among operators with different levels of expertise, with a rapid learning curve.

Prospective, multicentre observational study of point-of-care ultrasound practice in emergency departments across Australia and New Zealand: The POCUS-ED Registry

OBJECTIVES

The present study aimed to describe the characteristics, performance, accuracy and significance of point-of-care ultrasound (POCUS) use in the ED, by utilising an expanded version of the ACEM-mandated special skills placement (SSP) logbook, to develop a novel clinical quality registry.

METHODS

A prospective, observational study was performed across EDs in Australia and New Zealand over a 12-month period. Trainees undertaking ACEM-approved ultrasound (US) SSPs recorded all US scan interpretations and follow-up imaging reports in an online database.

RESULTS

In total, 2647 USs were recorded by 26 special skills trainees across 10 EDs in Australia or New Zealand; of these 2356 scans (89%) were clinically indicated. Overall, 2493 scans (94%) were used for diagnostic assessment, of which 1147 (43%) had abnormal findings. Basic echocardiography, extended Focused Assessment with Sonography in Trauma and right upper quadrant scans were the most commonly used modalities. There were 134 US-guided procedures logged in the registry. Approximately 36% of scans were reported to alter the original provisional diagnosis, whereas in another 37% of cases, POCUS was thought to confirm the original clinical suspicion. The majority of scans (76.5%) entered into the registry were physically reviewed by the SSP supervisor.

CONCLUSIONS

This multicentred registry provides a detailed description of the current utilisation of POCUS within special skills US placements across EDs in Australia and New Zealand. This data should inform clinical leaders in emergency US to improve both POCUS education and governance around this important tool.

Lung Ultrasound: A Diagnostic Leading Tool for SARS-CoV-2 Pneumonia: A Narrative Review

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread worldwide causing a global pandemic. In this context, lung ultrasound (LUS) has played an important role due to its high diagnostic sensitivity, low costs, simplicity of execution and radiation safeness. Despite computed tomography (CT) being the imaging gold standard, lung ultrasound point of care exam is essential in every situation where CT is not readily available nor applicable. The aim of our review is to highlight the considerable versatility of LUS in diagnosis, framing the therapeutic route and follow-up for SARS-CoV-2 interstitial syndrome.

Effects of Lung Ultrasonography-Guided Management on Cumulative Fluid Balance and Other Clinical Outcomes: A Systematic Review

Lung ultrasonography is accurate in detecting pulmonary edema and overcomes most limitations of traditional diagnostic modalities. Whether use of lung ultrasonography-guided management has an effect on cumulative fluid balances and other clinical outcomes remains unclear. In this systematic review, we included 12 studies using ultrasonography guided-management with a total of 2290 patients. Four in-patient studies found a reduced cumulative fluid balance (ranging from -0.3 L to -2.4 L), whereas three out-patient studies found reduction in dialysis dry weight (ranging from -2.6 kg to -0.2 kg) compared with conventionally managed patients. None of the studies found adverse effects related to hypoperfusion. The use of lung ultrasonography-guided management was not associated with other clinical outcomes. This systematic review shows that lung ultrasonography-guided management, exclusively or in concert with other diagnostic modalities, is associated with a reduced cumulative fluid balance. Studies thus far have not shown a consistent effect on clinical outcomes.

Diagnostic performances of lung ultrasound associated with inferior vena cava assessment for the diagnosis of acute heart failure in elderly emergency patients: a diagnostic study

BACKGROUND AND IMPORTANCE

Few studies are looking at the usefulness of lung ultrasound combined with inferior vena cava (ultrasound strategy) in the particularly challenging diagnosis of acute heart failure (AHF) in elderly dyspneic patients attending the emergency department (ED).

OBJECTIVE, DESIGN, SETTINGS, AND PARTICIPANTS

This was a prospective diagnostic study conducted in two French EDs from December 2015 to March 2019, aimed to determine the accuracy of an ultrasound strategy for the diagnosis of AHF in the elderly. Patients aged 65 and older referred to the ED for dyspnea were screened for inclusion.

INTERVENTION

An emergency physician, blinded to the first findings, performed chest ultrasound, and assessment of inferior vena cava (ultrasound strategy).

OUTCOME MEASURE AND ANALYSIS

The primary endpoint was a final diagnosis of AHF, adjudicated by two independent experts after reviewing the entire medical record. The sensitivity and specificity of ultrasound and standard strategies were calculated.

MAIN RESULTS

A total of 116 patients were included, mean age 84 years (SD 9). Among them, there were 76 (66%) cases of AHF and 51 (44%) cases of pneumonia. The ultrasound work up had a sensitivity of 82% [95% confidence interval (CI), 71-90] and a specificity of 68% (95% CI, 51-90] for AHF. The standard strategy had a sensitivity of 92% (95% CI, 84-97) and a specificity of 53% (95% CI, (36-68).

CONCLUSIONS

In this prospective study, there was no statistically significant difference between point-of-care ultrasound and a combination of clinical, radiographic, and biological findings for the diagnosis of acute heart failure.

Diagnostic accuracy of lung ultrasound for SARS-CoV-2: a retrospective cohort study

Background

As medical infrastructures are strained by SARS-CoV-2, rapid and accurate screening tools are essential. In portions of the world, reverse transcription polymerase chain reaction (RT-PCR) testing remains slow and in limited supply, and computed tomography is expensive, inefficient, and involves exposure to ionizing radiation. Multiple studies evaluating the efficiency of lung point-of-care ultrasound (POCUS) have been published recently, but include relatively small cohorts and often focus on characteristics associated with severe illness rather than screening efficacy. This study utilizes a retrospective cohort to evaluate the test characteristics (sensitivity, specificity, likelihood ratios, predictive values) of lung POCUS in the diagnosis of SARS-CoV-2, and to determine lung score cutoffs that maximize performance for use as a screening tool.

Results

Lung POCUS examinations had sensitivity 86%, specificity 71.6%, NPV 81.7%, and PPV 77.7%. The Lung Ultrasound Score had an area under the curve of 0.84 (95% CI 0.78, 0.90). When including only complete examinations visualizing 12 lung fields, lung POCUS had sensitivity 90.9% and specificity 75.6%, with NPV 87.2% and PPV 82.0% and an area under the curve of 0.89 (95% CI 0.83, 0.96). Lung POCUS was less accurate in patients with a history of interstitial lung disease, severe emphysema, and heart failure.

Conclusions

When applied in the appropriate patient population, lung POCUS is an inexpensive and reliable tool for rapid screening and diagnosis of SARS-CoV-2 in symptomatic patients with influenza-like illness. Adoption of lung POCUS screening for SARS-CoV-2 may identify patients who do not require additional testing and reduce the need for RT-PCR testing in resource-limited environments and during surge periods.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13089-021-00217-7.

Lung ultrasound score predicts outcomes in COVID-19 patients admitted to the emergency department

BACKGROUND

During the COVID-19 pandemic, creating tools to assess disease severity is one of the most important aspects of reducing the burden on emergency departments. Lung ultrasound has a high accuracy for the diagnosis of pulmonary diseases; however, there are few prospective studies demonstrating that lung ultrasound can predict outcomes in COVID-19 patients. We hypothesized that lung ultrasound score (LUS) at hospital admission could predict outcomes of COVID-19 patients. This is a prospective cohort study conducted from 14 March through 6 May 2020 in the emergency department (ED) of an urban, academic, level I trauma center. Patients aged 18 years and older and admitted to the ED with confirmed COVID-19 were considered eligible. Emergency physicians performed lung ultrasounds and calculated LUS, which was tested for correlation with outcomes. This protocol was approved by the local Ethics Committee number 3.990.817 (CAAE: 30417520.0.0000.0068).

RESULTS

The primary endpoint was death from any cause. The secondary endpoints were ICU admission and endotracheal intubation for respiratory failure. Among 180 patients with confirmed COVID-19 who were enrolled (mean age, 60 years; 105 male), the average LUS was 18.7 ± 6.8. LUS correlated with findings from chest CT and could predict the estimated extent of parenchymal involvement (mean LUS with < 50% involvement on chest CT, 15 ± 6.7 vs. 21 ± 6.0 with > 50% involvement, p < 0.001), death (AUC 0.72, OR 1.13, 95% CI 1.07 to 1.21; p < 0.001), endotracheal intubation (AUC 0.76, OR 1.17, 95% CI 1.09 to 1.26; p < 0.001), and ICU admission (AUC: 0.71, OR 1.14, 95% CI 1.07 to 1.21; p < 0.001).

CONCLUSIONS

In COVID-19 patients admitted in ED, LUS was a good predictor of death, ICU admission, and endotracheal intubation.

Point of care and intensive care lung ultrasound: A reference guide for practitioners during COVID-19

Objectives

Current events with the recent COVID-19 outbreak are necessitating steep learning curves for the NHS workforce. Ultrasound, although not used in the diagnosis of COVID-19 may be utilised by practitioners at the point of care (POC) or on the intensive care units (ITUs) where rapid assessment of the lung condition may be required. The aim of this article was to review current literature surrounding the use of lung ultrasound in relation to COVID-19 and provide Sonographers with a quick and digestible reference guide for lung pathologies.

Key findings

Ultrasound is being used in Italy and China to help review lung condition during the COVID-19 outbreak however not strictly as a diagnostic tool as Computed Tomography (CT) of the chest and chest radiographs are currently gold standard. Ultrasound is highly sensitive in the detection of multiple lung pathologies which can be demonstrated in conjunction with COVID-19 however to date there are no specific, nor pathognomonic findings which relate to COVID-19 on ultrasound.

Conclusion

Lung ultrasound is highly sensitive and can quickly and accurately review lung condition creating potential to assess for changes or resolution over time, especially in the ITU and POC setting. However it should not be used as a diagnostic tool for COVID-19 due to low specificity in relation to the virus.

Implications for practice

The adoption of lung ultrasound to monitor lung condition during the COVID-19 outbreak may reduce the need for serial exposure to ionising radiation on the wards and in turn reduce the number of radiographers required to attend infected wards and bays, protecting both patients and the workforce.

Can non-physician advanced retrieval practitioners (ARP) acquire and interpret diagnostic views of the lungs with sufficient quality to aid in the diagnosis of pneumothorax in the pre-hospital and retrieval environment?

Background

As an adjunct to physical examination, ultrasound is a potentially attractive option for diagnosing pneumothoraces in the pre-hospital and retrieval environment – and could confer a benefit to patient safety. However, the published evidence supporting non-physicians use of ultrasound in this setting is limited.

Aim

We aimed to establish if Advanced Retrieval Practitioners (non-physicians) could acquire ultrasound views of the lungs and interpret them with sufficient quality to diagnose pneumothorax in the pre-hospital and retrieval environment when compared to expert review.

Method

The study consisted of an observational trial from April 2017 to April 2018. Twelve (12) patients bilateral lung ultrasound images (24 images) were randomly selected from 87 patients assessed using Point of Care Ultrasound (POCUS) by three Advanced Retrieval Practitioners in the Pre-hospital and Retrieval environment. Two expert reviewers’ evaluated these images to determine ARPs ability to acquire diagnostic quality images and interpret them correctly. CXR results of patients in whom lung ultrasound was undertaken were recorded as the reference standard investigation.

Results

Within the 22 images considered adequate by the Advanced Retrieval Practitioners, 19 (86.4%, one-tailed McNemar test p = 0.125) were considered adequate on expert review. Of the 19 images mutually considered as adequate, both the Advanced Retrieval Practitioners and the reviewers identified two pneumothoraces which were subsequently confirmed on chest x-ray (Sensitivity 100% and Specificity 100% in technically adequate images). One pneumothorax was detected on CXR in a patient with inadequate ultrasound images. Advanced Retrieval Practitioners were therefore able to both obtain adequate images and correctly diagnose pneumothorax in the pre-hospital environment with 66.6% sensitivity (95%CI 66.6–100%) and 100% specificity (95%CI 81.0–100%) compared to expert review.

Conclusion

Advanced Retrieval Practitioners (non-physicians) can obtain diagnostic views of the lungs of sufficient quality to diagnose the presence, or particularly the absence, of pneumothorax in the pre-hospital and retrieval environment. Although Advanced Retrieval Practitioners were less accurate than the expert reviewers at interpreting the quality of the ultrasound images, the result was not statistically significant, despite the ARPs possibly having been at a methodological disadvantage.

Lung ultrasound score in establishing the timing of intubation in COVID-19 interstitial pneumonia: A preliminary retrospective observational study

PURPOSE

To investigate the role of lung ultrasound score (LUS) in assessing intubation timing for patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pneumonia.

MATERIALS AND METHODS

Seventy-two patients with critical coronavirus disease 2019 (COVID-19) were admitted to a makeshift intensive care unit (ICU). All patients underwent bedside lung ultrasonography one to two times per day. The patients were either intubated, treated with noninvasive ventilation (NIV), or given high-flow nasal cannula (HFNC) after a discussion with the multidisciplinary group after their conditions worsened. Bedside lung ultrasound was performed daily after intubation, and patients received mechanical ventilation. Lung ultrasound was performed on days 1, 2, 3, 5, and 7 after patients were admitted to the ICU; if the patient was intubated, LUS determination was performed before intubation within 24 h (T1) and on days 1, 2, 5, and 7 after intubation (T2, T3, T4, and T5, respectively).The goal of this study was to evaluate the severity of lung aeration loss in intubated and non-intubated patients with SARS-CoV-2 pneumonia by ultrasound at different time points within one week.

RESULTS

A total of 16 patients were included in this study, including nine who were intubated and mechanically ventilated and seven patients without intubation. The number of elderly individuals in the intubated group was higher than in the non-intubated group (P < 0.05). In addition, there were more male than female patients in both groups. Patient characteristics (BMI, SOFA, and PaO2/FiO2 value) were similar between the two groups (P > 0.05). The 28-day mortality rate of intubated patients was higher than that of non-intubated patients; six patients in the intubated group and two patients in the non-intubated group died. Nine intubated patients showed changes in LUS within seven days (n = 9). The mean LUS within 24 h before intubation was 12.8 ± 1.3. LUS was significantly higher on T1 than on T5 (P <0.05), and did not significantly differ from T1 to T4. Comparing LUS between intubated and non-intubated patients on T1 showed that the LUS of intubated patients was significantly higher than that of non-intubated patients (P <0.05). Between the two patient groups, oxygenation index was 140.1 ± 7.7 vs. 137.8 ± 5.9 on T1, and the respiratory rate of the two groups was 26 ± 5 vs. 28 ± 4 breaths/min. Neither oxygenation index nor RR significantly differed between the two groups.

CONCLUSION

LUS may be an effective tool for assessing intubation timing in critically ill patients with Covid-19 interstitial pneumonia.

Is Bigger Really Better? Comparison of Ultraportable Handheld Ultrasound with Standard Point-of-Care Ultrasound for Evaluating Safe Site Identification and Image Quality prior to Pleurocentesis

BACKGROUND

Pleural effusions remain a common medical problem which often requires diagnostic pleurocentesis to determine the underlying cause. Pleurocentesis is a frequently performed procedure worldwide with improved safety using ultrasound (US) technology.

OBJECTIVES

This prospective, single-center study evaluated the use of an ultraportable handheld (UPHH) US compared with standard point-of-care (SPOC) US in determining a safe site for pleurocentesis. In addition, US image quality and factors impacting on image quality were assessed using both UPHH and SPOC US.

METHODS

Paired US assessments were performed by thoracic physicians using UPHH and SPOC US on patients with unilateral pleural effusions to determine a safe site for pleurocentesis (defined as >2 cm of pleural fluid, >2 cm from a solid organ/diaphragm, and <7 cm chest wall depth). Distance measurements for key structures and image quality scores (using a 5-point Likert rating scale) were obtained at the time of US assessment. Factors affecting image quality were analyzed using univariate analysis.

RESULTS

In 52 of the 54 included patients (96.3%), UPHH US was able to identify a safe site for pleurocentesis. Distance measurements between UPHH and SPOC US were not statistically different (all <0.5 cm with values of p > 0.05), but image quality was reduced in UPHH compared with SPOC US by 1 point on a 5-point Likert rating scale (p < 0.002). Increasing body mass index was associated with a reduction in image quality in both UPHH and SPOC US (all p < 0.01).

CONCLUSIONS

Although image quality was lower in UPHH than SPOC US, a safe site was found in 96.3% of patients, which suggests that UPHH US may be a useful tool for diagnostic pleuro-centesis when SPOC US is not available (http://www.anzctr.org.au/, Australia New Zealand Clinical Trials Registry, No. ACTRN12618001592235).

Using lung ultrasound to quantitatively evaluate pulmonary water content

BACKGROUND

Increases in extravascular lung water (EVLW) can lead to respiratory failure. This study aimed to investigate whether the B-line score (BLS) was correlated with the EVLW content determined by the lung wet/dry ratio in a rabbit model.

METHODS

A total of 45 New Zealand rabbits were randomly assigned to nine groups. Among the animals, models of various lung water content levels were induced by the infusion of different volumes of warm sterile normal saline (NS) via the endotracheal tube. The arterial blood gas, spontaneous respiratory rate, and PaO₂ /FiO₂ ratio were detected before and after infusion. In addition, the B-lines were determined before and immediately after infusion in each group. Finally, both lungs were resected to determine the wet/dry ratio. In addition, all lung specimens were analyzed histologically, and EVLW was quantified using the BLS based on the number and confluence of B-lines in the intercostal space.

RESULTS

The BLS increased with increasing infusion volume. The BLS was statistically correlated with the wet/dry ratio (r² = .946) and with the PaO₂ /FiO₂ ratio (r² = .916). Furthermore, a repeatability study was performed for the lung ultrasound (LUS) technology (Bland-Altman plots), and the results suggest that LUS had favorable intraobserver and interobserver reproducibility.

CONCLUSIONS

This study is the first to suggest that the BLS can serve as a sensitive, quantitative, noninvasive, and real-time indicator of EVLW in a rabbit model of lung water accumulation. Notably, the BLS displayed an obvious correlation with the experimental gravimetry results and could also be used to predict the pulmonary oxygenation status.

Ultrasound guidance for volume management in patients with heart failure

Congestion is one of the most prominent characteristics of patients presented with decompensated heart failure and it implies unfavorable prognosis for the heart failure patient. Neurohumoral and immuno-inflammatory activation secondary to cardiac dysfunction constitute the pivotal mechanisms driving the heart failure syndrome that results in progressive fluid accumulation. In addition, fluid redistribution between different vascular compartments in human body guided from sympathetic activity constitutes another mechanism for heart failure decompensation. Ultrasound applied in the form of echocardiography provides invaluable data for the assessment of intracardiac filling pressures. The type of renal venous flow can provide the degree of renal congestion and probably insight into the pathophysiology of the decompensation of heart failure. Assessment of lung congestion in the patient with heart failure can be accomplished by lung ultrasonography. Additionally, clinical studies on the role of ultrasound in the management and prognosis of the congested patient are reviewed. Special heart failure population supported with left ventricular assist devices and extracorporeal membrane oxygenation support constitute an area where ultrasound guidance of fluid management has gained important role.

Quantitative estimation of extravascular lung water volume and preload by dynamic 15O-water positron emission tomography

AIMS

Left ventricular filling pressure (preload) can be assessed by pulmonary capillary wedge pressure (PCWP) during pulmonary arterial catheterization (PAC). An emerging method [pulse indexed contour cardiac output (PICCO)] can estimate preload by global end-diastolic volume (GEDV) and congestion as extravascular lung water (EVLW) content. However, no reliable quantitative non-invasive methods are available. Hence, in a porcine model of pulmonary congestion, we evaluated EVLW and GEDV by positron emission tomography (PET). The method was applied in 35 heart failure (HF) patients and 9 healthy volunteers.

METHODS AND RESULTS

Eight pigs were studied. Pulmonary congestion was induced by a combination of beta-blockers, angiotensin-2 agonist and saline infusion. PAC, PICCO, computerized tomography, and 15O-H2O-PET were performed. EVLW increased from 521 ± 76 to 973 ± 325 mL (P < 0.001) and GEDV from 1068 ± 170 to 1254 ± 85 mL (P < 0.001). 15O-H2O-PET measures of EVLW increased from 566 ± 151 to 797 ± 231 mL (P < 0.001) and GEDV from 364 ± 60 to 524 ± 92 mL (P < 0.001). Both EVLW and GEDV measured with PICCO and 15O-H2O-PET correlated (r2 = 0.40, P < 0.001; r2 = 0.40, P < 0.001, respectively). EVLW correlated with Hounsfield units (HU; PICCO: r2 = 0.36, P < 0.001, PET: r2 = 0.46, P < 0.001) and GEDV with PCWP (PICCO: r2 = 0.20, P = 0.01, PET: r2 = 0.29, P = 0.002). In human subjects, measurements were indexed (I) for body surface area. Neither EVLWI nor HU differed between chronic stable HF patients and healthy volunteers (P = 0.11, P = 0.29) whereas GEDVI was increased in HF patients (336 ± 66 mL/m2 vs. 276 ± 44 mL/m2, P = 0.01).

CONCLUSION

The present study demonstrates that 15O-H2O-PET can assess pulmonary congestion and preload quantitatively. Hence, prognostic information from 15O-H2O-PET examinations should be evaluated in clinical trials.