COMMENTARY

Use of POCUS to Diagnose Heart Failure

Faye Farber, MD, Yasmin Marcantonio, MD, Neil Stafford, MD, Shree Menon, MD, Megan Brooks, MD, MPH, FHM, Adam Wachter, MD, and Poonam Sharma, MD, SFHM

August 16, 2021

Case

A 65-year-old woman presents to the emergency department with a chief complaint of shortness of breath for 3 days. Medical history is notable for moderate chronic obstructive pulmonary disorder, systolic heart failure with last known ejection fraction (EF) of 35% and type 2 diabetes complicated by hyperglycemia when on steroids. You are talking the case over with colleagues and they suggest point-of-care ultrasound (POCUS) would be useful in her case.

Brief Overview of the Issue

Dr Faye Farber

Once mainly used by ED and critical care physicians, POCUS is now a tool that many hospitalists are using at the bedside. POCUS differs from traditional comprehensive ultrasounds in the following ways: POCUS is designed to answer a specific clinical question (as opposed to evaluating all organs in a specific region), POCUS exams are performed by the clinician who is formulating the clinical question (as opposed to by a consultative service such as cardiology and radiology), and POCUS can evaluate multiple organ systems (such as by evaluating a patient’s heart, lungs, and inferior vena cava to determine the etiology of hypoxia).

Hospitalist use of POCUS may include guiding procedures, aiding in diagnosis, and assessing effectiveness of treatment. Many high-quality studies have been published that support the use of POCUS and have proven that POCUS can decrease medical errors, help reach diagnoses in a more expedited fashion, and complement or replace more advanced imaging.

A challenge of POCUS is that it is user dependent and there are no established standards for hospitalists in POCUS training. As the Society of Hospital Medicine position statement on POCUS points out, there is a significant difference between skill levels required to obtain a certificate of completion for POCUS training and a certificate of competency in POCUS. Therefore, it is recommended hospitalists work with local credentialing committees to delineate the requirements for POCUS use.

Overview of the Data POCUS for Initial Assessment and Diagnosis of Heart Failure (HF)

Dr Yasmin Marcantonio

Use of POCUS in cases of suspected HF includes examination of the heart, lungs, and inferior vena cava (IVC). Cardiac ultrasound provides an estimated ejection fraction. Lung ultrasound (LUS) functions to examine for B lines and pleural effusions. The presence of more than three B lines per thoracic zone bilaterally suggests cardiogenic pulmonary edema. Scanning the IVC provides a noninvasive way to assess volume status and is especially helpful when body habitus prevents accurate assessment of jugular venous pressure.

Several studies have addressed the utility of bedside ultrasound in the initial assessment or diagnosis of acute decompensated heart failure (ADHF) in patients presenting with dyspnea in emergency or inpatient settings. Positive B lines are a useful finding, with high sensitivities, high specificities, and positive likelihood ratios. One large multicenter prospective study found LUS to have a sensitivity of 90.5%, specificity of 93.5%, and positive and negative LRs of 14.0 and 0.10, respectively.1 Another large multicenter prospective cohort study showed that LUS was more sensitive and more specific than chest x-ray (CXR) and brain natriuretic peptide in detecting ADHF.2 Additional POCUS findings that have shown relatively high sensitivities and specificities in the initial diagnosis of ADHF include pleural effusion, reduced left ventricular ejection fraction (LVEF), increased left ventricular end-diastolic dimension, and jugular venous distention.

Data also exists on assessments of ADHF using combinations of POCUS findings; for example, lung and cardiac ultrasound (LuCUS) protocols include an evaluation for B lines, assessment of IVC size and collapsibility, and determination of LVEF, although this has mainly been examined in ED patients. For patients who presented to the ED with undifferentiated dyspnea, one such study showed a specificity of 100% when a LuCUS protocol was used to diagnose ADHF while another study showed that the use of a LuCUS protocol changed management in 47% of patients.3,4 Of note, although each LuCUS protocol integrated the use of lung findings, IVC collapsibility, and LVEF, the exact protocols varied by institution. Finally, it has been established in multiple studies that LUS used in addition to standard workup including history and physical, labs, and electrocardiogram has been shown to increase diagnostic accuracy.2,5

Using POCUS to Guide Diuretic Therapy in HF

Dr Neil Stafford

To date, there have been multiple small studies published on the utility of daily POCUS in hospitalized patients with ADHF to help assess response to treatment and guide diuresis by looking for reduction in B lines on LUS or a change in IVC size or collapsibility. Volpicelli and colleagues showed that daily LUS was at least as good as daily CXR in monitoring response to therapy.6 Similarly, Mozzini and colleagues performed a randomized controlled trial of 120 patients admitted for ADHF who were randomized to a CXR group (who had a CXR performed on admission and discharge) and a LUS group (which was performed at admission, 24 hours, 48 hours, 72 hours, and discharge).7 This study found that the LUS group underwent a significantly higher number of diuretic dose adjustments as compared with the CXR group (P < .001) and had a modest improvement in LOS, compared with the CXR group. Specifically, median LOS was 8 days in CXR group (range, 4-17 days) and 7 days in the LUS group (range, 3-10 days; P < .001).

The Impact of POCUS on Length of Stay (LOS) and Readmissions

Dr Shree Menon

There is increasing data that POCUS can have meaningful impacts on patient-centered outcomes (morbidity, mortality, and readmission) while exposing patients to minimal discomfort, no venipuncture, and no radiation exposure. First, multiple studies looked at whether performing focused cardiac US of the IVC as a marker of volume status could predict readmission in patients hospitalized for ADHF.8,9 Both of these trials showed that plethoric, noncollapsible IVC at discharge were statistically significant predictors of readmission. In fact, Goonewardena and colleagues demonstrated that patients who required readmission had an enlarged IVC at discharge nearly 3 times more frequently (21% vs. 61%, P < .001) and abnormal IVC collapsibility 1.5 times more frequently (41% vs. 71%, P = .01) as compared with patients who remained out of the hospital.9

Similarly, a subsequent trial looked at whether IVC size on admission was of prognostic importance in patients hospitalized for ADHF and showed that admission IVC diameter was an independent predictor of both 90-day mortality (hazard ratio, 5.88; 95% confidence interval, 1.21-28.10; P = .025) and 90-day readmission (HR, 3.20; 95% CI, 1.24-8.21; P = .016).10 Additionally, LUS heart failure assessment for pulmonary congestion by counting B lines also showed that having more than 15 B lines prior to discharge was an independent predictor of readmission for ADHF at 6 months (HR, 11.74; 95% CI, 1.30-106.16).11

A Challenge of POCUS: Obtaining Competency

Dr Adam Wachter

As previously noted, there are not yet any established standards for training and assessing hospitalists in POCUS. The SHM Position Statement on POCUS recommends the following criteria for training5: the training environment should be similar to the location in which the trainee will practice, training and feedback should occur in real time, the trainee should be taught specific applications of POCUS (such as cardiac US, LUS, and IVC US) as each application comes with unique skills and knowledge, clinical competence must be achieved and demonstrated, and continued education and feedback are necessary once competence is obtained.12 SHM recommends residency-based training pathways, training through a local or national program such as the SHM POCUS certificate program, or training through other medical societies for hospitalists already in practice.

Application of the Data to Our Original Case

Dr Poonam Sharma

Targeted POCUS using the LuCUS protocol is performed and reveals three B lines in two lung zones bilaterally, moderate bilateral pleural effusions, EF 20%, and a noncollapsible IVC leading to a diagnosis of ADHF. Her ADHF is treated with intravenous diuresis. She is continued on her chronic maintenance chronic obstructive pulmonary disorder regimen but does not receive steroids, avoiding hyperglycemia that has complicated prior admissions. Over the next few days her respiratory and cardiac status is monitored using POCUS to assess her response to therapy and titrate her diuretics to her true dry weight, which was several pounds lower than her previously assumed dry weight. At discharge she is instructed to use the new dry weight which may avoid readmissions for HF.

Bottom Line

POCUS improves diagnostic accuracy and facilitates volume assessment and management in acute decompensated heart failure.

Farber is a medical instructor at Duke University and hospitalist at Duke Regional Hospital, both in Durham, N.C. Marcantonio is a medical instructor in the department of internal medicine and department of pediatrics at Duke University and hospitalist at Duke University Hospital and Duke Regional Hospital. Stafford and Brooks are assistant professors of medicine and hospitalists at Duke Regional Hospital. Wachter is associate medical director at Duke Regional Hospital and assistant professor at Duke University. Menon is a hospitalist at Duke University. Sharma is associate medical director for clinical education at Duke Regional Hospital and associate professor of medicine at Duke University.

References

1. Pivetta E et al. Lung ultrasound integrated with clinical assessment for the diagnosis of acute decompensated heart failure in the emergency department: A randomized controlled trial. Eur J Heart Fail. 2019 Jun;21(6):754-66. doi: 10.1002/ejhf.1379.

2. Pivetta E et al. Lung ultrasound-implemented diagnosis of acute decompensated heart failure in the ED: A SIMEU multicenter study. Chest. 2015;148(1):202-10. doi: 10.1378/chest.14-2608.

3. Anderson KL et al. Diagnosing heart failure among acutely dyspneic patients with cardiac, inferior vena cava, and lung ultrasonography. Am J Emerg Med. 2013;31:1208-14. doi: 10.1016/j.ajem.2013.05.007.

4. Russell FM et al. Diagnosing acute heart failure in patients with undifferentiated dyspnea: A lung and cardiac ultrasound (LuCUS) protocol. Acad Emerg Med. 2015;22(2):182-91. doi:10.1111/acem.12570.

5. Maw AM et al. Diagnostic accuracy of point-of-care lung ultrasonography and chest radiography in adults with symptoms suggestive of acute decompensated heart failure: A systematic review and meta-analysis. JAMA Netw Open. 2019 Mar 1;2(3):e190703. doi:10.1001/jamanetworkopen.2019.0703.

6. Volpicelli G et al. Bedside ultrasound of the lung for the monitoring of acute decompensated heart failure. Am J Emerg Med. 2008 Jun;26(5):585-91. doi:10.1016/j.ajem.2007.09.014.

7. Mozzini C et al. Lung ultrasound in internal medicine efficiently drives the management of patients with heart failure and speeds up the discharge time. Intern Emerg Med. 2018 Jan;13(1):27-33. doi: 10.1007/s11739-017-1738-1.

8. Laffin LJ et al. Focused cardiac ultrasound as a predictor of readmission in acute decompensated heart failure. Int J Cardiovasc Imaging. 2018;34(7):1075-9. doi:10.1007/s10554-018-1317-1.

9. Goonewardena SN et al. Comparison of hand-carried ultrasound assessment of the inferior vena cava and N-terminal pro-brain natriuretic peptide for predicting readmission after hospitalization for acute decompensated heart failure. JACC Cardiovasc Imaging. 2008;1(5):595-601. doi:10.1016/j.jcmg.2008.06.005.

10. Cubo-Romano P et al. Admission inferior vena cava measurements are associated with mortality after hospitalization for acute decompensated heart failure. J Hosp Med. 2016 Nov;11(11):778-84. doi: 10.1002/jhm.2620.

11. Gargani L et al. Persistent pulmonary congestion before discharge predicts rehospitalization in heart failure: A lung ultrasound study. Cardiovasc Ultrasound. 2015 Sep 4;13:40. doi: 10.1186/s12947-015-0033-4.

12. Soni NJ et al. Point-of-care ultrasound for hospitalists: A Position Statement of the Society of Hospital Medicine. J Hosp Med. 2019 Jan 2;14:E1-6. doi: 10.12788/jhm.3079.

Key Points

  • Studies have found POCUS improves the diagnosis of acute decompensated heart failure in patients presenting with dyspnea.

  • Daily evaluation with POCUS has decreased length of stay in acute decompensated heart failure.

  • Credentialing requirements for hospitalists to use POCUS for clinical care vary by hospital.

Additional Reading

Maw AM and Soni NJ. Annals for hospitalists inpatient notes – why should hospitalists use point-of-care ultrasound? Ann Intern Med. 2018 Apr 17;168(8):HO2-HO3. doi: 10.7326/M18-0367.

Lewiss RE. “The ultrasound looked fine”: Point of care ultrasound and patient safety. AHRQ’s Patient Safety Network. WebM&M: Case Studies. 2018 Jul 1. https://psnet.ahrq.gov/web-mm/ultrasound-looked-fine-point-care-ultrasound-and-patient-safety.

Quiz: Testing Your POCUS Knowledge

POCUS is increasingly prevalent in hospital medicine, but use varies among different disease processes. Which organ system ultrasound or lab test would be most helpful in the following scenario?

An acutely dyspneic patient with no past medical history presents to the ED. Chest x-ray is equivocal. Of the following, which study best confirms a diagnosis of acute decompensated heart failure?

A. Brain natriuretic peptide

B. Point-of-care cardiac ultrasound

C. Point-of-care lung ultrasound

D. Point-of-care inferior vena cava ultrasound

 

Answer

C. Point-of-care lung ultrasound

Multiple studies, including three systematic reviews, have shown that point-of-care lung ultrasound has high sensitivity and specificity to evaluate for B lines as a marker for cardiogenic pulmonary edema. Point-of-care ultrasound of ejection fraction and inferior vena cava have not been evaluated by systematic review although one randomized, controlled trial showed that an EF less than 45% had 74% specificity and 77% sensitivity and IVC collapsibility index less than 20% had an 86% specificity and 52% sensitivity for detection of acute decompensated heart failure. This same study showed that the combination of cardiac, lung, and IVC point-of-care ultrasound had 100% specificity for diagnosing acute decompensated heart failure. In the future, health care providers could rely on this multiorgan evaluation with point-of-care ultrasound to confirm a diagnosis of acute decompensated heart failure in a dyspneic patient.

This article originally appeared on MDedge.com, part of the Medscape Professional Network.

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