RULING OUT PE: A NOVEL APPROACH USING END-TIDAL CO2 WITH COMPRESSION ULTRASONOGRAPHY AND TRANSTHORACIC ECHOCARDIOGRAPHY IN PULMONARY EMBOLISM DIAGNOSIS (CUEPED)

Abstract

ABSTRACT

Background: Diagnosis of pulmonary embolism (PE) remains a challenge in clinical practice, especially in emergency setting despite availability of various diagnostic tools. It is desirable to have a rapid and accurate bedside test to rule out PE.

Objective: The aim of this study is to evaluate the diagnostic accuracy of CUEPED, a novel method of ruling out pulmonary embolism using a combination of end-tidal CO₂ (ETCO2), Compression Ultrasonography (CUS) and Transthoracic Echocardiography (TTE).

Methods: In this pilot study, patients who presented to the Emergency Department at University Malaya Medical Centre with suspected acute PE from December 2013 to October 2014 who fulfilled the inclusion and exclusion criteria, were assessed using CUEPED. CUEPED was considered positive if the measured ETCO2 was less than 35 mmHg, or if there was presence of venous incompressibility in lower limb ultrasonography or if   tricuspid annular plane systolic excursion (TAPSE) in transthoracic echocardiography was less than 1.6. All patients received a computed tomography pulmonary angiography (CTPA) for confirmation of diagnosis. Data obtained was analyzed to determine if a negative CUEPED has the potential to accurately rule out a PE.

Results: 30 patients (mean age = 48 years [SD = 13.6]) were involved with an equal distribution between gender. The incidence of PE was 56.7%. CUEPED had a sensitivity of 100% for PE. Negative CUEPED ruled out PE with a negative predictive value of 100%. Positive CUEPED ruled in PE with a low specificity of 53.8% and moderate positive predictive value of 73.9%.

Conclusion: This diagnostic study showed that a negative CUEPED is potentially accurate in ruling out PE.

Keywords: pulmonary embolism, End-tidal CO2, compression ultrasound, transthoracic echocardiography