Chia-Ching Chen

AIM

Point of care ultrasonography (POCUS) is a low-cost, real-time, noninvasive modality which may rapidly narrow the differential diagnosis and improve chance of survival.

We discuss a case of massive pulmonary embolism with cardiac arrest diagnosed by POCUS.

INTRODUCTION

Pulmonary embolism (PE) is one of obstructive shock which can result in shock and cardiac arrest.

Effectively early diagnosing pulmonary embolism can be difficult due to limited information, broad differentials, and the severity of illness demanding rapid intervention.

Point of care ultrasonography (POCUS) is a low-cost, real-time, noninvasive modality, which may rapidly narrow the differential diagnosis and improve chance of survival.

We discuss a case of massive pulmonary embolism with cardiac arrest diagnosed by POCUS.

CASE PRESENTATION

A 86-yer-old woman was brought in by ambulance with the chief complaint of dyspnea and hematemesis.

She was reported by the paramedics to be hypotensive, tachypnea and tachycardic prior to arrival.

Her past medical history was hypertension, heart failure and atrial septal defect.

On presentation to the emergency department, the patient appeared critically ill with generalized pallor with a heart rate of 103 beats per minute (bpm), blood pressure of 121/72 mm Hg, and oxygen saturation of 79% on 15 L O2 via a nonrebreather mask.

Her exam was significant for pale conjunctiva, grunting, otherwise clear bilateral breath sounds, rapid but regular heart tones, weak femoral pulses, and symmetric, and non-edematous lower extremities. Shortly after arrival the patient lost cardiac motion, and cardiopulmonary resuscitation (CPR) was initiated with return of spontaneous circulation within 10 minutes.

She was emergently intubated, and his postintubation oxygen saturation was noted to be 84%, despite 100% FiO2 and confirmation of adequate tube placement. POCUS was performed with visualization of an enlarged right ventricle (figure 1a), RV systolic pressure (RVSP) 34mmHg (figure 1b) and a pulmonary acceleration time (PAT) 60msec (figure 1c), tricuspid annular plane systolic excursion (TAPSE) 11mm (figure d) and direct visualize left main trunk of pulmonary artery thrombus (figure 2a), highly suspicious for a massive pulmonary embolus.

The patient’s blood pressure was maintained on a continuous infusion of dopamine. The CT angiogram (CTA) confirmed the diagnosis of bilateral massive pulmonary emboli (figure 2b).

DISCUSSION

Our case demonstrates successful application of POCUS in the diagnosis of massive PE in a patient with dyspnea and PEA.

Although thrombolytics were given immediately after confirmation of PE by CTA, the direct sonographic evidence of pulmonary artery thrombus and indirect sonographic evidence acute RV strain and 60/60 rule strongly suggested the diagnosis.

tPA was not given due to active GI tract bleeding. Delay in initiating thrombolytic therapy until CTA was reasonable due to lacking strong evidence level of ED-performed POCUS for PE diagnosis.

Direct sonographic evidence of acute PE include free-floating in RV thrombus or pulmonary artery and indirect signs as inferior vena cava plethora, RV dilation, D shape LV wall in parasternal short axis view, TAPSE<18mm, 60/60 rule or evidence of DVT on compression ultrasound of the lower extremities.

As stated in the ACC/ASE appropriateness criteria document, transthoracic echocardiography is not sufficiently sensitive to rule out pulmonary embolism. Although the direct visualization of thrombus in right ventricle or pulmonary artery with acute RV strain is highly specific for acute pulmonary embolism, the sensitivity of this direct sign is as low as 4–18%.

The sensitivity of indirect signs of acute PE varies from 29% to77%. And such indirect sign can also be found in other disease such as COPD, obstructive sleep apnea, pulmonary hypertension, and right sided myocardial infarction.

Currently the most sensitive and specific indirect sign is the McConnell sign (hypokinesis of the RV mid-free wall with preserved apical contractility in apical four-chamber view) with sensitivity of 77% and specificity of 94%.

Even though, current policy published by ACEP and ASE still recommend considering thrombolytics if the clinical scenario and the POCUS findings suggest massive pulmonary embolus in the peri-arrest patient.