Point-of-Care Ultrasound and Right Ventricular Strain: Utility in the Diagnosis of Pulmonary Embolism

Ramzi Ibrahim MD, João Paulo Ferreira MD

Department of Medicine, University of Arizona – Tucson and Banner University Medical Center

Tucson AZ USA

Abstract

Pulmonary emboli are associated with high morbidity and mortality, prompting early diagnostic and therapeutic considerations. Utilization of rapid point-of-care ultrasound (POCUS) to assess for signs of pulmonary emboli can provide valuable information to support immediate treatment. We present a case of suspected pulmonary embolism in the setting of pharmacological prophylaxis for venous thromboembolism with identification of right heart strain on bedside POCUS exam. Early treatment with anticoagulation was initiated considering the clinical presentation and POCUS findings. CT angiogram of the chest revealed bilateral pulmonary emboli, confirming our suspicion. Utilizing POCUS in a case of suspected pulmonary emboli can aid in clinical decision making.

Case Presentation

Our patient is a 50-year-old man with a history of morbid obesity, obstructive sleep apnea, and poorly controlled diabetes mellitus type 2 who was admitted to the hospital for sepsis secondary to left foot cellulitis and found to have left foot osteomyelitis with necrosis of the calcaneus. The patient was started on intravenous antimicrobials, underwent incision and debridement, and completed a partial calcanectomy of the left foot. During the hospital course, he remained on subcutaneous unfractionated heparin at 7,500 units three times a day for prevention of deep vein thrombosis. On post-operative day 12, he developed acute onset of dyspnea requiring 2 liters of supplemental oxygen and was slightly tachycardic in the low 100s. He complained of chest tightness without pain, however, he denied lower extremity discomfort, palpitations, orthopnea, or diaphoresis. Electrocardiogram was remarkable for sinus tachycardia without significant ST changes, T-wave inversions, conduction defects, or QTc prolongation. Rapid point-of-care ultrasound (POCUS) at bedside revealed interventricular septal bowing, hypokinesia of the mid free right ventricular wall, and increased right ventricle to left ventricle size ratio (>1:1 respectively) (Figures 1 and 2).

Figure 1. A: Static apical 4-chamber view showing interventricular bowing into the left ventricle (blue arrow), significantly enlarged right ventricle, and right ventricular free wall hypokinesia (green arrow). B: Video of apical 4-chamber view.

Figure 2. A: Static parasternal short axis view showing interventricular septal bowing in the left ventricle (green arrow). B: Video of parasternal short axis view.

With these findings, the patient was started on therapeutic anticoagulation. CT angiogram of the chest revealed a large burden of bilateral pulmonary emboli (PE). The pulmonary embolism severity index (PESI) score was 130 points which is associated with a 10%-24.5% mortality rate in the following 30 days. Formal echocardiogram showed a severely dilated right ventricle with reduced systolic function, paradoxical septal movement, and a D-shaped left ventricle. Patient remained hemodynamically stable and was discharged home after transition from heparin to rivaroxaban.

Discussion

Pulmonary emboli remain a commonly encountered pathological phenomenon in the hospital setting with a mortality rate ranging from <5% to 50% (1). Venous thromboembolism prophylaxis has been shown to reduce the risk of VTE in hospitalized patients, however, this does not eliminate the risk completely. Prompt diagnosis allows earlier treatment and improved outcomes however this is often challenging given the lack of specificity associated with its characteristic clinical symptoms (2). In the proper context, utilization of POCUS can aid the diagnosis of PE by assessing for signs of right ventricular strain. Characteristic findings seen on a cardiac-focused POCUS that represent right ventricular strain include McConnell’s sign (defined as right ventricular free wall akinesis/hypokinesis with sparing of the apex), septal flattening, right ventricular enlargement, tricuspid regurgitation, and tricuspid annular plane systolic excursion under 1.6 cm (3). Their respective sensitivities and specificities are highly dependent on the pre-test probability. For example, a prospective cohort study completed by Daley et al. (4) in 2019 showed that for patients with a clinical suspicion of PE, sensitivity of right ventricular strain was 100% for a PE in patients with a heart rate (HR) >110 beats per minute, and a sensitivity of 92% if HR >100 BPM. This study provides evidence to support the use of cardiac focused POCUS in ruling out pulmonary emboli in patients with signs of right ventricular strain and abnormal hemodynamic parameters such as tachycardia. Additionally, in settings where hemodynamic instability is present and the patient cannot be taken to the CT scanner for fear of decompensation, rapid POCUS assessment can be helpful. In our patient, given the acute need for supplemental oxygenation and dyspnea, along with his risk factors for a thromboembolic event, the use of POCUS aided in our clinical decision making. The yield of information that can be provided by POCUS is vital for early diagnostic and therapeutic decision making for patients with a clinical suspicion of pulmonary emboli.

References

1. Torbicki A, Perrier A, Konstantinides S, et al. Guidelines on the diagnosis and management of acute pulmonary embolism: the Task Force for the Diagnosis and Management of Acute Pulmonary Embolism of the European Society of Cardiology (ESC). Eur Heart J. 2008 Sep;29(18):2276-315. [CrossRef][PubMed]
2. Roy PM, Meyer G, Vielle B, et al. Appropriateness of diagnostic management and outcomes of suspected pulmonary embolism. Ann Intern Med. 2006 Feb 7;144(3):157-64. [CrossRef][PubMed]
3. Alerhand S, Sundaram T, Gottlieb M. What are the echocardiographic findings of acute right ventricular strain that suggest pulmonary embolism? Anaesth Crit Care Pain Med. 2021 Apr;40(2):100852. [CrossRef] [PubMed]
4. Daley JI, Dwyer KH, Grunwald Z, et al. Increased Sensitivity of Focused Cardiac Ultrasound for Pulmonary Embolism in Emergency Department Patients With Abnormal Vital Signs. Acad Emerg Med. 2019 Nov;26(11):1211-1220. [CrossRef][PubMed]

Cite as: Ibrahim R, Ferreira JP. Point-of-Care Ultrasound and Right Ventricular Strain: Utility in the Diagnosis of Pulmonary Embolism. Southwest J Pulm Crit Care Sleep. 2022;25(2):34-36. doi: https://doi.org/10.13175/swjpccs040-22 PDF

Ultrasound for Critical Care Physicians: Sometimes It’s Better to Be Lucky than Smart

Robert A. Raschke MD and Randy Weisman MD

Critical Care Medicine

HonorHealth Scottsdale Osborn Medical Center

Scottsdale, AZ USA

We recently responded to a code arrest alert in the rehabilitation ward of our hospital. The patient was a 47-year-old man who experienced nausea and diaphoresis during physical therapy. Shortly after the therapists helped him sit down in bed, he became unconsciousness and pulseless. The initial code rhythm was a narrow-complex pulseless electrical activity (PEA). He was intubated, received three rounds of epinephrine during approximately 10 minutes of ACLS/CPR before return of spontaneous circulation (ROSC), and was subsequently transferred to the ICU.

Shortly after arriving, a 12-lead EKG was performed (Figure 1), and PEA recurred.

Figure 1. EKG performed just prior to second cardiopulmonary arrest showing S1 Q3 T3 pattern (arrows).

Approximately ten-minutes into this second episode of ACLS, a cardiology consultant informed the code team of an S1,Q3,T3 pattern on the EKG. A point-of-care (POC) echocardiogram performed during rhythm checks was technically-limited, but showed a dilated hypokinetic right ventricle (see video 1).

Video 1. Echocardiogram performed during ACLS rhythm check: Four-chamber view is poor quality, but shows massive RV dilation and systolic dysfunction.

Approximately twenty-minutes into the arrest, 50mg tissue plasminogen activator (tPA) was administered, and return of spontaneous circulation (ROSC) achieved two minutes later. A tPA infusion was started. The patient’s chart was reviewed. He had received care in our ICU previously, but this wasn’t immediately recognized because he had subsequently changed his name of record to the pseudonym “John Doe” (not the real pseduonym), creating two separate and distinct EMR records for the single current hospital stay. Review of the first of these two records, identified by his legal name, revealed he had been admitted to our ICU one month previously for a 5.4 x 3.6 x 2.9 cm left basal ganglia hemorrhage. We stopped the tPA infusion.

On further review of his original EMR is was noted that two weeks after admission for intracranial hemorrhage, (and two weeks prior to cardiopulmonary arrest), he had experienced right leg swelling and an ultrasound demonstrated extensive DVT of the right superficial femoral, saphenous, popliteal and peroneal veins. An IVC filter had been due to anticoagulant contraindication. The patient’s subsequent rehabilitation had been progressing well over the subsequent two weeks and discharge was being discussed on the day cardiopulmonary arrest occurred.

On post-arrest neurological examination, the patient gave a left-sided, thumbs-up to verbal request. Ongoing hypotension was treated with a norepinephrine infusion and inhaled epoprostenol. An emergent head CT was performed and compared to a head CT from four weeks previously (Figure 2), showing normal evolution of the previous intracranial hemorrhage without any new bleeding. 

Figure 2. CT brain four weeks prior to (Panel A), and immediately after cardiopulmonary arrest and administration of tPA (Panel B), showing substantial resolution of the previous intracranial hemorrhage.

A therapeutic-dose heparin infusion was started. An official echo confirmed the findings of our POC echo performed during the code, with the additional finding of McConnell’s sign. McConnell’s sign is a distinct echocardiographic finding described in patients with acute pulmonary embolism with regional pattern of right ventricular dysfunction, with akinesia of the mid free wall but normal motion at the apex (1). A CT angiogram showed bilateral pulmonary emboli, and interventional radiology performed bilateral thrombectomies. Hypotension resolved immediately thereafter. The patient was transferred out of the ICU a few days later and resumed his rehabilitation.

A few points of interest:

• IVC filters do not absolutely prevent life-threatening pulmonary embolism (2,3).
• Sometimes, serendipity smiles, as when the cardiologist happened into the room during the code, and provided an essential bit of information.
• Emergent POC ultrasonography is an essential tool in the management of PEA arrest of uncertain etiology.
• Barriers to access of prior medical records can lead to poorly-informed decisions. But in this case, ignorance likely helped us make the right decision.
• Giving lytic therapy one month after an intracranial hemorrhage is not absolutely contra-indicated when in dire need.
• As the late great intensivist, Jay Blum MD used to say: “Sometimes it’s better to be lucky than smart.”

References

1. Ogbonnah U, Tawil I, Wray TC, Boivin M. Ultrasound for critical care physicians: Caught in the act. Southwest J Pulm Crit Care. 2018;17(1):36-8. [CrossRef]
2. Urban MK, Jules-Elysee K, MacKenzie CR. Pulmonary embolism after IVC filter. HSS J. 2008 Feb;4(1):74-5. [CrossRef] [PubMed]
3. PREPIC Study Group. Eight-year follow-up of patients with permanent vena cava filters in the prevention of pulmonary embolism: the PREPIC (Prevention du Risque d'Embolie Pulmonaire par Interruption Cave) randomized study. Circulation. 2005 Jul 19;112(3):416-22. doi: [CrossRef] [PubMed]

Cite as: Raschke RA, Weisman R. Ultrasound for Critical Care Physicians: Sometimes It’s Better to Be Lucky than Smart. Southwest J Pulm Crit Care. 2021;22(6):116-8. doi: https://doi.org/10.13175/swjpcc016-21 PDF