SonoCase: Thoracic aortic aneurysms – and a review of the literature #FOAMed

Thoracic aortic aneurysms are much less common than abdominal aortic aneurysms. And, to top it off, the measurements of the thoracic aorta are different than the abdominal aorta, especially in the ascending thoracic aorta. It’s good to know how to look at the thoracic aorta when you need to, and what the normal measurements are so that you can make that immediate decision when a thoracic aneurysm (or dissection) is detected.

Drs. Daignault, Saul, and Lewiss published 2 great case reports in the Journal of EM Aug 2013 issue (subscription needed) on thoracic aortic aneurysms. One patient was a 60 year old male who had blunt trauma to his back by a heavy piece of plaster while at work. He had a BP of 140/80 mm Hg and HR of 90 beats/min. The FAST was negative for free fluid but the aortic root was found to be 5.49cm. This caused them to order a CT angio confirming their findings.  Another patient was an 82 year old male with 1 month of chest pain radiating to his back with history of aortic valve repair and HTN on coumadin. BP was 210/90 mm Hg. A bedside echo was performed and showed descending thoracic aorta aneurysm measuring 4.82cm.  This had a CT Angio done confirming descending thoracic aneurysm.  The abstract is found here, and a prior post on these case reports can be found here.

These cases bring up an excellent reason to review the thoracic aorta. The best cardiac echo view to see visualize the thoracic aorta, if you could only pick one, would be the parasternal long view.

According to a german study where they looked at the thoracic aorta throughout life from 17 to 89 yrs of age  via helical CT with the following methods and results: “Methods: Seventy adults, 17 to 89 years old, without any signs of cardiovascular disease were investigated with helical computed tomography. Aortic diameters were measured at seven predefined thoracic levels. Results: Aortic diameters (mean ± SD) were 2.98 ± 0.46 cm at the aortic valve sinus, 3.09 ± 0.41 cm at the ascending aorta, 2.94 ± 0.42 cm proximal to the innominate artery, 2.77 ± 0.37 cm at the proximal transverse arch, 2.61 ± 0.41 cm at the distal transverse arch, 2.47 ± 0.40 cm at the isthmus, and 2.43 ± 0.35 cm at the diaphragm. Men had slightly longer diameters than did women. All diameters increased with age. There was no influence of weight, height, or body surface area.”

More recently, Medscape authors state that the thoracic aorta dimensions are larger than the abdominal aorta dimensions and that aneursymal definition occurs when it is greater than 50% of the normal size.

Another study in the radiology literature with many more subjects more recently, had the following methods and results: “Methods: 1442 consecutive subjects who were referred for evaluation of possible coronary artery disease underwent coronary CT angiography (CTA) and coronary artery calcium scanning (CACS) (55+11 years, 65% male) without known coronary heart disease, hypertension, chronic pulmonary and renal disease, diabetes and severe aortic calcification. The ascending aortic diameter, descending aortic diameter (DAOD), pulmonary artery (PAD) and chest anterioposterior diameter (CAPD), posterior border of sternal bone to anterior border of spine, were measured at the slice level of mid right pulmonary artery by using end systolic trigger image. The volume of four chambers, ejection fraction of left ventricle, and cardiac output were measured in 56% of the patients. Patients demographic information, age, gender, weight, height and body surface area (BSA), were recorded. The mean value and age specific and gender adjusted upper normal limits (mean + 2 standard deviations) were calculated. The linear correlation analysis was done between AAOD and all parameters. The reproducibility, wall thickness and difference between end systole and diastole were calculated. Result: AAOD has significant linear association with age, gender, descending aortic diameter and pulmonary artery diameter (P<0.05). There is no significant correlation between AAOD and body surface area, four chamber volume, LVEF, CO and CAPD. The mean Intra-luminal AAOD was 31.1 ± 3.9mm and 33.6 ± 4.1 mm in females and males respectively. The upper normal limits (mean + 2 standard deviations) of Intra-luminal AAOD, mean+ standard deviation, was 35.6, 38.3 and 40 mm for females and 37.8, 40.5 and 42.6 mm for males in age group 20 to 40, 41 to 60, above 60 year respectively. Intra-luminal should parallel echocardiography and invasive angiography. Traditional cross sectional imaging (with computed tomography and magnetic resonance imaging) includes the vessel wall. The mean total AAOD was 33.5mm and 36.0 mm in females and males respectively. The upper normal limits (mean + 2 standard deviations) of Intra-luminal AAOD, mean+ standard deviation, was 38.0, 40.7 and 42.4 mm for females and 40.2, 42.9 and 45.0 mm for males in age group 20 to 40, 41 to 60, above 60 year respectively. The inter and intra observer, scanner and repeated measurement variability was low (R value >0.91, P<0.001, coefficient variation <3.2%). AAOD was 1.7 mm less in end-diastole than end systole(P<0.001).” Below is their table illustrating the various measurements by others:

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As Dr Lewiss and colleagues state in their case reports, “The most recent consensus statement by the American Society of Echocardiography (ASE) and the American College of Emergency Physicians (ACEP) recognized that the thoracic aortic pathology can be identified on EP-performed focused cardiac ultrasound (3). Transthoracic echocardiography was shown to be consistent with TEE for measurement of the ascending aorta (21). Taylor et al. demonstrated that EP-performed focused cardiac ultrasound was consistent with CTA measurements for maximal thoracic aortic diameter (2). In these cases, an EP with considerable experience in ultrasound performed these studies, but many EP are trained in the use of focused ultrasound for evaluation of the abdominal aorta. Principals used in this application, such as avoiding measurements in oblique planes, measuring from outer wall to outer wall (for the descending thoracic aorta), and the use of Doppler also may be utilized in the evaluation of the thoracic portion of the aorta.”

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:

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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.

SonoStudy: Flat IVC predictor of poor prognosis in trauma – A-B-C-D-Echo in Trauma!

A recent study on the IVC and trauma and acute surgical patients was done by Ferrada et al, and despite the giggles I get when I read it and how they describe the IVC as “Fat ” or “Flat”, it is an important topic to discuss as it is one of the few articles out there that correlate the iVC to trauma patients and acute surgical patients. First off, it is a retrospective study, which can make it difficult to assess patients with similar factors without other factors coming into play (but when is that NOT the case, honestly?) They did compare the IVC in all patients and studied those patients who seemed sick as well – ICU admission, immediate surgery need, transfusion needed. The power of the study was good but not great – 101 patients studied – varying in type of trauma and surgical need. There was a previous study published in the Journal of Trauma in 2011 that stated CT evidence of flat IVC was an indicator for hypovolemia and  poor prognostic indicator for blunt solid organ injuries – this confirmed a study done in 2010 stating the same thing. Thankfully, ultrasound can get you that information much more immediately than CT!

This month, another study by the same author (Ferrada) in the Journal of trauma and acute care surgery entitled A-B-C-D-Echo (I know, love it!) stated that adding limited transthoracic echo, including the IVC, will benefit trauma patients with results showing “Flat inferior vena cava was associated with an increased incidence of ICU admission (p < 0.0076) and therapeutic operation (p < 0.0001). Of the 148 patients, 27 (18%) had LTTE results indicating euvolemia. The diagnosis in these cases was head injury (n = 14), heart dysfunction (n = 5), spinal shock (n = 4), pulmonary embolism (n = 3), and stroke (n = 1). Of the patients, 121 had LTTE results indicating hypovolemia. Twenty-eight hypovolemic patients had a negative or inconclusive Focused Assessment with Sonography for Trauma examination finding (n = 18 penetrating, n = 10 blunt), with 60% having blood in the abdomen confirmed by surgical exploration or computed tomographic scan. Therapy was modified as a result of LTTE in 41% of cases. Strikingly, in patients older than 65 years, LTTE changed therapy in 96% of cases.”

Below are the Abstracts of the studies highlighted by Ferrada:

“Flat inferior vena cava (IVC) on ultrasound examination has been shown to correlate with hypovolemic status. We hypothesize that a flat IVC on limited echocardiogram (LTTE) performed in the emergency room (ER) correlates with poor prognosis in acutely ill surgical patients. We conducted a retrospective review of all patients undergoing LTTE in the ER from September 2010 until June 2011. IVC diameter was estimated by subxiphoid window. Flat IVC was defined as diameter less than 2 cm. Fat IVC was defined as diameter greater than 2 cm. Need for intensive care unit admission, blood transfusion requirement, mortality, and need for emergent operation between patients with flat versus Fat IVC were compared. One hundred one hypotensive patients had LTTE performed in the ER. Average age was 38 years. Admission diagnosis was blunt trauma (n = 80), penetrating trauma (n = 13), acute care surgery pathology (n = 7), and burn (n = 1). Seventy-four patients had flat IVC on initial LTTE. Compared with those with fat IVC, flat patients were found have higher rates of intensive care unit admission (51.3 vs 14.8%; P = 0.001), blood transfusion requirement (12.2 vs 3.7%), and mortality (13.5 vs 3.7%). This population also underwent emergent surgery on hospital Day 1 more often (16.2 vs 0%; P = 0.033). Initial flat IVC on LTTE is an indicator of hypovolemia and a predictor of poor outcome.”

ABCDEcho:

“BACKGROUND: Limited transthoracic echocardiogram (LTTE) has been introduced as a technique to direct resuscitation in intensive care unit (ICU) patients. Our hypothesis is that LTTE can provide meaningful information to guide therapy for hypotension in the trauma bay.

METHODS: LTTE was performed on hypotensive patients in the trauma bay. Views obtained included parasternal long and short, apical, and subxyphoid. Results were reported regarding contractility (good vs. poor), fluid status (flat inferior vena cava [hypovolemia] vs. fat inferior vena cava [euvolemia]), and pericardial effusion (present vs. absent). Need for surgery, ICU admission, Focused Assessment with Sonography for Trauma examination results, and change in therapy as a consequence of LTTE findings were examined. Data were collected prospectively to evaluate the utility of this test.

RESULTS: A total of 148 LTTEs were performed in consecutive patients from January to December 2011. Mean age was 46 years. Admission diagnosis was 80% blunt trauma, 16% penetrating trauma, and 4% burn. Subxyphoid window was obtained in all patients. Parasternal and apical windows were obtained in 96.5% and 11%, respectively. Flat inferior vena cava was associated with an increased incidence of ICU admission (p < 0.0076) and therapeutic operation (p < 0.0001). Of the 148 patients, 27 (18%) had LTTE results indicating euvolemia. The diagnosis in these cases was head injury (n = 14), heart dysfunction (n = 5), spinal shock (n = 4), pulmonary embolism (n = 3), and stroke (n = 1). Of the patients, 121 had LTTE results indicating hypovolemia. Twenty-eight hypovolemic patients had a negative or inconclusive Focused Assessment with Sonography for Trauma examination finding (n = 18 penetrating, n = 10 blunt), with 60% having blood in the abdomen confirmed by surgical exploration or computed tomographic scan. Therapy was modified as a result of LTTE in 41% of cases. Strikingly, in patients older than 65 years, LTTE changed therapy in 96% of cases.

CONCLUSION: LTTE is a useful tool to guide therapy in hypotensive patients in the trauma bay.”

SonoStudy and Tutorial: EPSS vs fractional shortening for LV function – is EPSS good enough?

In a recent issue of the Journal of Ultrasound through AIUM, Weekes et al. (and Kendall et al in AM J EM) talk about a hot topic that emergency and critical care physicians hold dear to them – the EPSS , or E-point septal separation – the minimal distance between the anterior mitral valve leaflet and the interventricular septum in the parasternal long view of the cardiac echo during diastole using M-Mode. Now, EPSS is not a part of point of care echo right now (i know, phew!), but there are conversations about whether it should be. The reason is because it is thought that EPSS is a good tool for LV function delineation, possibly better than simple visualization, despite knowing the risks of underestimating ejection fraction due to endocardial output limitations (see below). …Yeah, I know, that’s a lot of words and it took me a year to really understand what the above meant. So, let’s talk about it…especially as it is included in the updated RUSH protocol by Seif, Perera, et al.

EPSS by echo has even been compared to cardiac MRI for LV function recently. And, Dr. Mike Stone and friends did a study last year with regard to EPSS compared to qualitative LV function, stating: “Dyspneic patients with acute decompensated heart failure (ADHF) often present to the emergency department (ED), and emergency physicians (EPs) must act quickly and accurately to evaluate and diagnose patients with ADHF. Traditionally, key components of the patient’s history, physical examination, electrocardiography, and chest radiography are used to diagnose ADHF. However, no single test is highly accurate, and even with the incorporation of B-type natriuretic peptide levels, the diagnosis of ADHF in a dyspneic patient in the ED can be a challenge. Additional modalities that allow prompt and accurate diagnosis of ADHF would be of clinical utility, and estimation of left ventricle ejection fraction (LVEF) using point-of-care ultrasound has been the focus of prior research” showing that EPSS is a good tool compared to qualitative LVEF visualization. EM News folks also highlighted EPSS in a recent entry.

Now, lets talk a bit about the anatomy and physiology about this before we talk about the study. The mitral valve has an anterior leaflet and a posterior leaflet. You can see the mitral valve open and close in the parasternal long view of the heart. the below picture indicates the anterior leaflet:

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Using the Cardiovscular Institute’s diagrams, we can see the functioning of the mitral valve during systole and diastole in relation to the EKG, with every movement /peaks delineated with a letter  ….one of them being “e” (where E of EPSS comes from):

Screen shot 2012-12-14 at 10.46.50 AMScreen shot 2012-12-14 at 10.48.15 AM

…and in relation to the EKG on M-mode on the PSL view (aka motion mode – basically visualizing the motion of objects in time).

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EPSS of >7mm is thought to be an indication of poor LV function. Some use 1cm as the mark to increase their sensitivity for low ejection fraction. So, you can see that it should be a good indicator of LV function.

Fractional shortening (FS), however, is….(LVEDd-LVESd) / LVEDd expressed as a percentage. Placing the M-mode cursor across the LV just beyond the mitral valve leaflets, a tracing is shown whose measurements of the LV chamber diameter in both systole and diastole can illustrate FS, or LV contractility (not ejection fraction as it is not a volume measurement). Normal FS being 30-45%. For a complete description of these terms go here – a great overview by ICU Sonography –  and here – a simpler way to understand the measurements through the Stanford ICU website. The updated RUSH protocol, also explains this well, with images from their most recent publication below:

Hyperdynamic/hypercontractile: FS >45%

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Abnormal: hypocontractile LV: FS<30%

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So, the study was a prospective study, thankfully, and seemed to really want EPSS to be good for LV function, but it looks like it’s not as good as we think:

Abstract: “Objectives Rapid bedside assessment of left ventricular (LV) function can aid in the evaluation of the critically ill patient and guide clinical management. Our primary hypothesis was that mitral valve E-point septal separation measurements would correlate with contemporaneous fractional shortening measurements of LV systolic function when performed by emergency physicians. Our secondary hypothesis was that E-point septal separation as a continuous variable would predict fractional shortening using a linear regression model.

Methods We studied a prospective convenience sample of patients undergoing a sequence of LV systolic function measurements during a 3-month period at a suburban academic emergency department with a census of 114,000 patients. The sample included adult emergency department patients who were determined by the treating emergency physician to have 1 or more clinical indications for bedside LV systolic function assessment. Investigators performed bedside M-mode cardiac sonographic measurements of fractional shortening and E-point septal separation using the parasternal long-axis window. The sequence of LV systolic function measurements was randomized.

Results A total of 103 patients were enrolled. The Pearson correlation coefficient for E-point septal separation and fractional shortening measurements was –0.59 (P< .0001). Linear regression analysis performed for E-point septal separation with fractional shortening as the dependent variable yielded an R2 value of 0.35.

Conclusions E-point septal separation and fractional shortening measurements had a moderate negative correlation. E-point septal separation, when used as a continuous variable in a linear regression model, did not reliably predict fractional shortening.”

The limitations of EPSS as discussed in Stone’s paper:

Valvular diseases that restrict anterior mitral leaflet motion ( mitral stenosis, aortic insufficiency) – will exaggerate EPSS.

Asymmetric septal hypertrophy,

Severe left ventricular hypertrophy,

Discrete proximal septal thickening (sigmoid septum) can lead to small
estimates of EPSS.

Failure to obtain a true parasternal long-axis view may result in falsely elevated
EPSS measurements due to a tangential measurement from mitral valve leaflet to septal wall.

….At the end of the day, my opinion -> just visualizing the LV contractility, as long as you have a good PSL and PSS long view, and you’ve seen enough to know normal versus abnormal, is good enough for me!

SonoStudy: Survival potential – US evaluating cardiac motion during traumatic cardiac arrest… AND an assessment of the literature

An interesting study in the July issue of the Journal of Trauma and Acute Care Surgery (see full article here) discussing the utility of bedside ultrasound during traumatic cardiac arrest. For anyone who works at a trauma center, or who just so happens to receive a patient dropped off by a friend on the driveway of the ED (we have all had that happen), or who received a patient by ambulance who is in cardiac arrest at a non-trauma center to soon find evidence of trauma upon exposure of the patient….. this study is quite relevant when it comes to survival potential and how bedside ultrasound may help. What they say….

Continue reading

SonoStudy (and Case): 53% of septic patients’ treatment plans changed after seeing the IVC and cardiac contractility

The study coming out in Annals of Emergency Medicine in June done by Haydar et al “found point-of-care ultrasonographic data about cardiac contractility, inferior vena cava diameter, and inferior vena cava collapsibility to be clinically useful in treating adult patients with sepsis” – for those of us who use US regularly to evaluate patients in shock, whether it’s by using the RUSH protocol or evaluating the initial and post-fluid volume status for those we are trying to resuscitate when septic, it’s no big surprise. What is the surprising aspect of this is that 53% of septic patients’ treatment plans had changed due to the findings by ultrasound of cardiac contractility and IVC appearance. Continue reading

SonoStudy: Top Research in Bedside US – the short of breath patient

Very cool review article on the evaluation of the short of breath patient by bedside US…. the RADIUS study – strong name, if I do say so myself…