SonoStudy: Echo/Lung Ultrasound in Ambulatory Dyspneic Pts & Prior HF #FOAMus #FOAMed

In the study published in feb 2014 on ambulatory patients and those with prior heart failure, an obvious indirect message is given: do bedside US in ambulatory patients and you will be able to identify disease processes for which your exam or chest Xray may have limited value. Another message is how the heart relates to the presence of B lines on Lung US. This is correlating to another study that compared lung US to BNP value, cliical assessment and echo.

For a quick review of what B lines look like – see below: Using the phased array or curvilinear probe, place the probe over 8 different zones of the chest wall (4 on each side – 2 anterior and 2 lateral) and if you see these bright “rockets” coming down from the pleural line to the end of the screen when you are at 16cm depth, that is a B line. More than 2 B lines in more than 2 zones, bilaterally, from a thin pleural line is consistent with pulmonary edema. Using your cardiac echo to confirm contractility issues helps confirm the findings. To see more of the tutorial, go here.

See the abstract below:

“Lung ultrasound (LUS) represents a novel, noninvasive method in the assessment of extravascular lung water. We investigated the utility of LUS in ambulatory subjects with dyspnea or prior heart failure (HF).

METHODS:

We studied 81 ambulatory subjects with HF history or dyspnea who underwent transthoracic echocardiography (TTE) with LUS of 8 zones. Subjects with heart transplantation or pulmonary conditions known to interfere with LUS were excluded. A reviewer blinded to the clinical data performed echocardiographic measurements and quantified B-lines (reverberation artifacts arising from the pleural line).

RESULTS:

Of 81 subjects, 74 (91%) (median age 66 years, 39% men, median left ventricular ejection fraction [LVEF] 54%, 39% with prior HF) had adequate LUS images of all 8 zones and were included in the analysis. The number of B-lines ranged from 0-12 (median 2). Increased B-lines, analyzed by tertiles, were associated with larger left ventricular (LV) end-diastolic (P = 0.036) and end-systolic diameters (P = 0.026), septal wall thickness (P = 0.009), LV mass index (P = 0.001), left atrial (LA) volume index (P = 0.005), tricuspid regurgitation (TR) velocity (P = 0.005) and estimated pulmonary artery systolic pressure (PASP) (P = 0.003). In a secondary analysis associations between B-lines (not grouped by tertiles) and LV mass index, LA volume index, TR velocity and PASP remained stable after adjustment for age, gender, BMI and HF history.

CONCLUSIONS:

Sonographic B-lines from LUS are related to measures of LV and LA structure and right ventricular pressure in ambulatory patients with dyspnea or prior HF. The added clinical and prognostic utility of this imaging modality in ambulatory patients warrants further investigation.”

SonoStudy: Ultrasound of heart and lungs identify preeclamptic pregnant patients at risk

In anesthesiology literature (not yet on pubmed), heart and lung ultrasound has entered the mix to identify pregnant patients at risk for respiratory failure – looking for hypocontractile heart and B lines! Oh yeah! It has received a lot of press, see here, here and here :

“Chicago — (March 18, 2014)

An ultrasound of the lungs could help doctors quickly determine if a pregnant woman with preeclampsia is at risk for respiratory failure, suggests preliminary research published in the April issue of Anesthesiology.

About 60,000 women worldwide die as a result of preeclampsia, which causes severely high blood pressure. Potential complications include stroke, bleeding and excess fluid in the lungs – called pulmonary edema – which can lead to respiratory failure.  The study suggests a lung ultrasound can help doctors easily learn whether a woman with preeclampsia is suffering from pulmonary edema and ensure she receives the correct treatment.

“Lung Ultrasound is fast, safe, noninvasive and easy to use,” said Marc Leone, M.D., Ph.D., lead author of the study and vice chair of the department of anesthesiology and critical care medicine, Hopital Nord, Marseille, France. “We found it allowed us to quickly assess whether a woman with preeclampsia had pulmonary edema and confirm the severity of the condition.”

Doctors often measure urine output to determine if a woman needs fluid administration, but the results are wrong about half of the time. “Lung ultrasound enables the medical team to identify which women really need the fluid treatment,” noted Dr. Zieleskiewicz, the study’s  first author.

Pulmonary edema is typically caused by heart failure, but also can be caused by lung inflammation. Researchers analyzed the use of lung ultrasounds, which can assess lung  edema, are easier to use than cardiac ultrasound and can be performed with devices commonly found in maternity wards. Lung ultrasound highlights white lines mimicking comet tails, irradiating from the border of the lungs. These lines are the reflection of water in the lungs.  The detection of three or more lines strongly suggests the diagnosis of pulmonary edema.

Researchers performed both cardiac and lung ultrasounds before and after delivery in 20 women with severe preeclampsia.  Five of the 20 women (25 percent) had pulmonary edema prior to delivery according to lung ultrasound, while four (20 percent) had the condition according to the cardiac ultrasound. The lung ultrasound identified a patient with non-cardiac pulmonary edema, which the cardiac ultrasound did not detect.

The test results could help ensure that pregnant women with pulmonary edema not be given intravenous or excess fluids, which worsens the condition and can lead to respiratory failure.  Typically, women with pulmonary edema are treated with oxygen and medication to lower the blood pressure or rid the body of excess fluid.  In real time, lung ultrasound also serves to observe improvement or worsening of pulmonary edema.”

SonoStudies: Thoracic Ultrasound for Pulmonary Embolism #FOAMed

Thoracic ultrasound is one of the most highly changing and advancing applications of bedside ultrasound, and the research that has been published on the utility of this application for our patients cannot be ignored. It can aid (and is better than chest Xray) in pneumothorax evaluation, pleural effusion assessment (only need 15cc of fluid to see it on ultrasound!), pneumonia evaluation, and pulmonary edema assessment. See prior posts here, here and here with literature referenced to read about all of that – trust me it’s worth it!). Of course, if you add cardiac echo to your evaluation for acute pulmonary embolism, the studies suggest it helps to look for McConnells sign and RV dilation and strain (which is a bad prognostic indicator for PE). Recently, there was a case report published in J of EM of a PE-in-transit diagnosed by bedside echo, leading to expedited care and ability to know the cause of suden cardiac arrest in a patient. For a clip of what it may look like for a “mobile mass” seen in RA, click here. Another study in J of EM was done concluding that ED bedside ultrasound echo results  predicted PE adverse outcomes.

Seeing RV dilation/strain can help but are seen mainly when the patient is hemodynamically unstable. Could thoracic ultrasound identify subsegmental pulmonary embolism in patients who are not hemodynamically unstable? Interesting question and I truly hope so…

So, if that wasnt enough, now it can help with pulmonary embolism evaluation??? What?! That is great and i hope that this teaser of a study below can be repeated and found to be valid. It would be great. Now, there have been a few others, like a meta-analysis showing that thoracic ultrasound should not be ignored when suspecting PE, a review of chest ultrasound for pulmonary diseases showing its utility, and a case report and review by the Italians (who are huge researchers in thoracic ultrasound where I listen to pretty much everything they say about it).

This recent study in Annals of Thoracic Medicine, physicians in Turkey evaluate the use of bedside ultrasound for the evaluation of pulmonary embolism. The abstract is below:

“OBJECTIVES: The diagnosis of pulmonary embolism (PE) is still a problem especially at emergency units. The purpose of study was to determine the diagnostic accuracy of thoracic ultrasonography (TUS) in patients with PE.

METHODS: In this prospective study, 50 patients with suspected PE were evaluated in Department of Pulmonary Diseases of a Training and Reasearch Hospital between January 2010 and July 2011. At the begining, TUS was performed by a chest physician, subsequently for definitive diagnosis computed tomography pulmonary angiography were performed in all cases as a reference method. Other diagnostic procedures were examination of serum d-dimer levels, echocardiography, and venous doppler ultrasonography of the legs. Both chest physician and radiologist were blinded to the results of other diagnostic method. Diagnosis of PE was suggested if at least one typical pleural-based/subpleural wedge-shaped or round hypoechoic lesion with or without pleural effusion was reported by TUS. Presence of pure pleural effusion or normal sonographic findings were accepted as negative TUS for PE.

RESULTS: PE was diagnosed in 30 patients. It was shown that TUS was true positive in 27 patients and false positive in eight and true negative in 12 and false negative in three. Sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of TUS in diagnosis of PE for clinically suspected patients were 90%, 60%, 77.1%, 80%, and 78%, respectively.

CONCLUSIONS: TUS with a high sensitivity and diagnostic accuracy, is a noninvasive, widely available, cost-effective method which can be rapidly performed. A negative TUS study cannot rule out PE with certainty, but positive TUS findings with moderate/high suspicion for PE may prove a valuable tool in diagnosis of PE at bedside especially at emergency setting, for critically ill and immobile patients, facilitating immediate treatment decision.”

From the BLUE protocol by Lichtenstein on how to distinguish the various etiologies of shortness of breath, an algorithm was given (see below) which includes the utility of bedside ultrasound for pulmonary embolism diagnosis:

A Profile: anterior A lines bilaterally only – absence of interstitial syndrome – with lung sliding

A’ profile: A profile without lung sliding

B profile – anterior B lines bilaterally with lung sliding

B’ profile – B profile without lung sliding

A/B profile – A lines on one side and B lines present on the other side (asymmetry)

C profile – anterior consolidation (shred sign)

Normal – A profile without PLAPS

PLAPS = posterolateral alveolar and/or pleural syndrome

Thoracic US and the BLUE protocol

A good presentation on thoracic US for pulmonary embolism can be found here:

SonoStudy: 550 pts, prospective study: How good is ultrasound for traumatic pneumothorax? @westjem #FOAMed

In the march 2013 issue of Western Journal of Emergency Medicine, a study done that has been described as having generalizability, as the ultrasound scans were by many different levels of physicians, prospectively, during a trauma assessment for pneumothorax, has caused quite a bit of discussion. Mostly due to some of the limitations of the study. It is great that a prospective study with some generalizability is seen, but I wonder about the details in the methodology. They begin by discussing the importance and relevance of ultrasound for pneumothorax:

“Rapid diagnosis and treatment of traumatic pneumothorax (PTX) is important to prevent tension physiology and circulatory collapse in patients with blunt and penetrating trauma. Supine chest radiograph (CXR) is traditionally employed; however, it misses up to 50% of PTXs.1 Thoracic ultrasound (TUS) was first described in 1995 for diagnosing PTX in humans when Lichtenstein noted that the absence of comet-tail artifacts and lung sliding were associated with PTX.2 Since then ultrasound has become a validated method of examining the pleura in multiple settings. In 2011 the Eastern Association for the Surgery of Trauma gave a level 2 recommendation for the use of ultrasound to identify PTX in its practice management guidelines.3 In most studies TUS has been found to have favorable results. In Lichtenstein’s study,2 TUS had a sensitivity and negative predictive value of 100% and 96.5%, respectively, for the detection of PTX in the intensive care unit setting.4 Dulchavsky5 subsequently demonstrated that this modality has a sensitivity of 95% in the detection of PTX in patients at a Level 1 trauma center. These reports used plain radiography as the gold standard: a diagnostic modality known to be inaccurate in the detection of PTX.6 In subsequent studies using dedicated chest computed tomography (CCT) as a reference standard, sensitivities of TUS have ranged widely from 49% – 98%, while finding that it is still consistently more accurate than supine CXR.713 Studies in which TUS is performed by emergency physicians (EP) for traumatic PTX have reported even higher sensitivities ranging from 86–97% with specificities of > 99%.14 While these latter numbers are desirable, they have the potential limitation of being less applicable due to a higher skill level of the sonologists involved. The actual performance of TUS for PTX would likely vary based on the sonologist’s skill and experience. The current investigation set out to determine the test characteristics of TUS for traumatic PTX in the hands of a large heterogenous group of potential sonologists representative of typical clinicians involved in trauma care.”

The full abstract is shown below:

“Introduction:

Prior studies have reported conflicting results regarding the utility of ultrasound in the diagnosis of traumatic pneumothorax (PTX) because they have used sonologists with extensive experience. This study evaluates the characteristics of ultrasound for PTX for a large cohort of trauma and emergency physicians.

Methods:

This was a prospective, observational study on a convenience sample of patients presenting to a trauma center who had a thoracic ultrasound (TUS) evaluation for PTX performed after the Focused Assessment with Sonography for Trauma exam. Sonologists recorded their findings prior to any other diagnostic studies. The results of TUS were compared to one or more of the following: chest computed tomography, escape of air on chest tube insertion, or supine chest radiography followed by clinical observation.

Results:

There were 549 patients enrolled. The median injury severity score of the patients was 5 (inter-quartile range [IQR] 1–14); 36 different sonologists performed TUS. Forty-seven of the 549 patients had traumatic PTX, for an incidence of 9%. TUS correctly identified 27/47 patients with PTX for a sensitivity of 57% (confidence interval [CI] 42–72%). There were 3 false positive cases of TUS for a specificity of 99% (CI 98%–100%). A “wet” chest radiograph reading done in the trauma bay showed a sensitivity of 40% (CI 23–59) and a specificity of 100% (99–100).

Conclusion:

In a large heterogenous group of clinicians who typically care for trauma patients, the sonographic evaluation for pneumothorax was as accurate as supine chest radiography. Thoracic ultrasound may be helpful in the initial evaluation of patients with truncal trauma.”

So what are the limitations? They describe a few of them:

The technique: “The TUS examination consisted of the consecutive sonographic interrogation of every intercostal space between the clavicle and the diaphragm on each hemithorax. Scans were performed in the mid-clavicular line. On the left side, if cardiac motion was encountered in the mid-clavicular line, the probe was moved laterally to the left anterior axillary line and the pleura seen in the remaining intercostal spaces was evaluated until the diaphragm/spleen was encountered. To use the ribs to assist in the identification of the rib spaces and the pleura, the probe was placed in a longitudinal plane for the entire exam.” So, would this have increased their sensitivity or specificity as they include all rib spaces? Not too sure. Is this truly generalizable if the technique is different than how most perform the quick E-FAST? no. The main reason for the technique, i imagine, is to find the lung point which is far more specific for pneumothorax.

The Probe and Machine – The low frequency curvilinear probe was used on an older ultrasound system – SonoSite Titan. Could this have affecte their results? Would the increased resolution of a linear probe have helped their evaluation on the newer machines? It is possible, but by how much? who knows.

The comparison group: “Not all subjects underwent CCT and instead just had CXR and clinical observation. It is possible that some patients in this latter group had radio-occult PTX that may have been visualized on CCT leading to misclassification bias. Such a bias could result in a lower sensitivity rate for both TUS and CXR, however would likely not affect the accuracy of these tests for determining clinically significant PTX.” It is tough to have a standard and if only the chest CT group were compared, it may have had different results.

Im hoping to see more studies like this one where more generalizability is seen, and not studies done only by the experts, so that we can have a true assessment. It is best done using the technique most commonly performed (using only the second intercostal space and mid clavicular line and trying to ind the lung point if absence of lung sliding is seen) at multiple-sites, with increased power to the study, all compared to a CT as the imaging gold standard. But, i can dream, as that is quite difficult to accomplish, and the authors did a pretty nice job with what they had, got pretty good numbers of subjects – something to ponder….

For a prior post on pneumothorax and a link to the CHEST meta-analysis, go here.

For a SonoTutorial post on pneumothorax ultrasound, go here.

Another study stating that ultrasound can be used to assess post=procedure pneumothorax published in June 2013 of JUM, go here.

SonoStudyReview: The Pneumothorax by @EMLyceum – EBM review on imaging/diagnosis/treatment #FOAMed

If there ever was a post worth reading about pneumothorax, this excellent review by EM Lyceum was too good not to pass along to everyone. Now I don’t know about you, but I always get asked the questions about chest Xray versus Ultrasound, what to do when only the ultrasound shows the pneumothorax (because you know it’s better than Chest Xray! as discussed in a prior post), when to order that CT chest, and how should you treat it: nothing? pigtail? small chest tube? large chest tube? EM Lyceum does a great job in reviewing this using literature to back it up. There have been more studies that haven’t been mentioned with regard to ultrasound and pneumothorax diagnosis, and the sensitivity and specificity of chest xray is stated pretty high as prior studies tend to do (with more accurate and recent ones stated by EM Lyceum to be lower (in the real world that we work in). And, there was a great meta-analysis in Chest Journal speaking of which imaging modality was better, chest Xray or ultrasound. Go to the EM Lyceum site and read-on to grasp the answers to all the questions! Thank you EM Lyceum – this was awesome!

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By BTS 2010 guidelines (Macduff, 2010).

SonoStudy: Thoracic ultrasound in identifying pneumothorax progression in the intubated – the lung point

In the Feb 2013 issue of Chest, Oveland et al studied porcine models, introducing air at incremental levels to identify if thoracic ultrasound is as accurate as CT scanning for the detection pneumothorax progression in the intubated patient. They found that “the accuracy of thoracic ultrasonography for identifying the lung point (and, thus, the PTX extent) was comparable to that of CT imaging. These clinically relevant results suggest that ultrasonography may be safe and accurate in monitoring PTX progression during positive pressure ventilation.”

“Background:  Although thoracic ultrasonography accurately determines the size and extent of occult pneumothoraces (PTXs) in spontaneously breathing patients, there is uncertainty about patients receiving positive pressure ventilation. We compared the lung point (ie, the area where the collapsed lung still adheres to the inside of the chest wall) using the two modalities ultrasonography and CT scanning to determine whether ultrasonography can be used reliably to assess PTX progression in a positive-pressure-ventilated porcine model.

Methods:  Air was introduced in incremental steps into five hemithoraces in three intubated porcine models. The lung point was identified on ultrasound imaging and referenced against the lateral limit of the intrapleural air space identified on the CT scans. The distance from the sternum to the lung point (S-LP) was measured on the CT scans and correlated to the insufflated air volume.

Results:  The mean total difference between the 131 ultrasound and CT scan lung points was 6.8 mm (SD, 7.1 mm; range, 0.0-29.3 mm). A mixed-model regression analysis showed a linear relationship between the S-LP distances and the PTX volume (P < .001).

Conclusions:  In an experimental porcine model, we found a linear relation between the PTX size and the lateral position of the lung point. The accuracy of thoracic ultrasonography for identifying the lung point (and, thus, the PTX extent) was comparable to that of CT imaging. These clinically relevant results suggest that ultrasonography may be safe and accurate in monitoring PTX progression during positive pressure ventilation.”

Full article found here.

To see the lung point, you visualize the pleural line using the linear probe (indicator toward the patient’s head) starting from anterior chest wall (2nd intercostal space, mid-clavicular line) to inferior-lateral chest wall, and look out for the area where the lack of lung sliding or comet tail artifacts reverts back to normal lung sliding with comet tail artifacts. Blaivas, et al, studied this, showing that bedside ultrasound can detect size of pneumothorax through identification of the lung point location. Below is a video fo the lung point:

SonoStudy & Review of literature: Rapid Lung/cardiac/IVC – differentiates causes of acute dyspnea

A recent study in cardiovascular medicine … a concept that has been highlighted in varying ways from prior studies (by Liteplo (ETUDES study), Lichtenstein (all of his studies, actually), Volpicelli (ILC-LUS international consensus), and Manson with the RADIUS study/protocol), continues to conclude that rapid bedside ultrasound of lung/cardiac/IVC can help differentiate causes of acute dyspnea. The state: “The present study demonstrated that rapid evaluation by lung-cardiac-inferior vena cava (LCI) integrated ultrasound has a higher diagnostic accuracy for differentiating acute dyspnea due to AHFS from pulmonary acute dyspnea (including COPD/asthma, pulmonary fibrosis, and ARDS) compared with lung ultrasound either alone or in combination with plasma BNP assay. These findings suggest that LCI integrated ultrasound has become a fundamental tool for diagnostic evaluation of patients with acute dyspnea and selection of early treatment in the emergency setting.”

The algorithm below is what they used:

1476-7120-10-49-1

ABSTRACT:

BACKGROUND: Rapid and accurate diagnosis and management can be lifesaving for patients with acute dyspnea. However, making a differential diagnosis and selecting early treatment for patients with acute dyspnea in the emergency setting is a clinical challenge that requires complex decision-making in order to achieve hemodynamic balance, improve functional capacity, and decrease mortality. In the present study, we examined the screening potential of rapid evaluation by lung-cardiac-inferior vena cava (LCI) integrated ultrasound for differentiating acute heart failure syndromes (AHFS) from primary pulmonary disease in patients with acute dyspnea in the emergency setting.

METHODS:

Between March 2011 and March 2012, 90 consecutive patients (45 women, 78.1 +/- 9.9 years) admitted to the emergency room of our hospital for acute dyspnea were enrolled. Within 30 minutes of admission, all patients underwent conventional physical examination, rapid ultrasound (lung-cardiac-inferior vena cava [LCI] integrated ultrasound) examination with a hand-held device, routine laboratory tests, measurement of brain natriuretic peptide, and chest X-ray in the emergency room.

RESULTS:

The final diagnosis was acute dyspnea due to AHFS in 53 patients, acute dyspnea due to pulmonary disease despite a history of heart failure in 18 patients, and acute dyspnea due to pulmonary disease in 19 patients. Lung ultrasound alone showed a sensitivity, specificity, negative predictive value, and positive predictive value of 96.2, 54.0, 90.9, and 75.0%, respectively, for differentiating AHFS from pulmonary disease. On the other hand, LCI integrated ultrasound had a sensitivity, specificity, negative predictive value, and positive predictive value of 94.3, 91.9, 91.9, and 94.3%, respectively.

CONCLUSIONS:

Our study demonstrated that rapid evaluation by LCI integrated ultrasound is extremely accurate for differentiating acute dyspnea due to AHFS from that caused by primary pulmonary disease in the emergency setting.