Point-of-Care Ultrasound in the Inpatient Setting: A Tale of Four Patients

Renee K. Dversdal, MD; KevinM. Piro, MD; Charles M. LoPresti, MD; Noelle M. Northcutt, MD; Daniel J. Schnobrich, MD

Disclosures

South Med J. 2018;111(7):382-388. 

In This Article

Case 3

A 69-year-old man with a history of hypertension, obesity, and stroke presented with a 2-week history of new-onset lower extremity swelling and abdominal distension. Admission vital signs were within normal limits. The physical examination noted hepatomegaly and anasarca. Admission laboratory values were notable for AKI, mild hypoalbuminemia, mild hepatic dysfunction, and normal N-terminal-pro B-type natriuretic peptide. Formal transabdominal US revealed liver masses and ascites. A complete transthoracic echocardiogram demonstrated normal biventricular systolic function, normal valvular motion and flow gradients, an intracaval mass, and a small pericardial effusion without tamponade.

On hospital day 3 he developed sinus tachycardia at rest into the 130s and tachypnea without hypoxia, while remaining normotensive. He was started on a heparin drip for concern of pulmonary embolus; however, the differential diagnosis for his new tachycardia and tachypnea remained broad. Using a handheld phased-array US probe with a portable tablet device, the team was able to evaluate multiple compartments in less than 5 minutes.

Literature Review and Discussion

POCUS allows for a rapid evaluation for the presence or absence of pericardial fluid and can support clinical findings that are suggestive of tamponade in a patient with a known effusion.[31,32] Focused cardiac ultrasound is achievable by physicians and trainees[33,34] and is recommended by the Society for Critical Care Medicine and the World Interactive Network Focused on Critical UltraSound in the evaluation of a pericardial effusion for signs of tamponade.[35–38] Focused cardiac US findings in tamponade include a plethoric IVC, which carries a sensitivity of 97% for tamponade in pericardial effusion,[39] and respiratory variation in ventricular volume, with a shift in septal motion toward the left ventricle in diastole when intrathoracic pressure is negative (the pulsus paradoxus on physical examination). As tamponade physiology progresses, the right ventricle can be seen to collapse during diastole, the right atrium collapses during systole (Figure 5), or both. Respiratory change in flow velocity across an atrioventricular valve is an example of an advanced echocardiography finding for tamponade.[40,41]

Figure 5.

Right atrial collapse during systole in apical window. Ao, aortic outflow tract; LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle. Corresponding ultrasound clips can be viewed at http://links.lww.com/SMJ/A110.

US Findings and Case Resolution

On examination the patient had pulmonary POCUS findings of A-lines (no interstitial edema pattern) and lung sliding (no pneumothorax). Tachycardia and tachypnea challenged clear views of the heart; however, views in the subcostal and apical windows demonstrated a small-to-moderate circumferential pericardial effusion. In the subcostal view the right ventricle collapsed intermittently during diastole with respiratory variation. In the apical window, the ventricular chambers demonstrated interventricular dependence with respiratory variation and atrial collapse during systole. The IVC was plethoric without respiratory variation, indicating elevated right heart pressures. Understanding that cardiac tamponade is a clinical diagnosis, the team then performed a pulsus paradoxus, which was 16 mm Hg (positive or abnormal when >10–12 mm Hg). The bedside diagnosis was early tamponade physiology without frank tamponade in this patient with stable blood pressure. The patient was evaluated rapidly by the consulting cardiology team, which agreed with the bedside examination and diagnosis and immediately transferred him to the intensive care unit for intravenous fluids and monitoring. Formal, cardiology-performed limited transthoracic echocardiogram several hours later confirmed early tamponade physiology with moderate pericardial effusion and atrioventricular valve respiratory variation.

This case demonstrates how POCUS can assist in the assessment of a complex medical inpatient and in the narrowing of a differential diagnosis. The objectivity gleaned from this POCUS examination supported communication among providers across specialties, avoided delays in the diagnostic workup, and improved care by expediting the transition to a higher level of care.

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