FOCUS May Be Useful for Ruling Out Pulmonary Embolism in Patients Presenting to the ED With Abnormal Vital Signs

In patients with abnormal vital signs who are seen in the emergency department (ED), particularly in patients with a heart rate (HR) ≥100 beats/min, who are suspected of having a pulmonary embolism (PE), a negative focused cardiac ultrasound (FOCUS) examination may be associated with reduced odds of a PE diagnosis, according to a study published in Academic Emergency Medicine.

Although FOCUS is generally considered insensitive for PE, a clot large enough to have an effect on vital signs should be detected during this examination (eg, indications of right ventricular dysfunction). A quick bedside test that could reliably rule out PE in these patients would prove extremely useful in the ED. Investigators hypothesized that in patients with tachycardia or hypotension, the sensitivity of FOCUS for the detection of PE would increase considerably.

In this multicenter prospective observational cohort study, the data of a convenience sample of 136 patients (mean age, 56 years; 59% women) who presented to the ED between April 2016 and November 2018 with suspected PE and tachycardia and/or hypotension and were evaluated using computed tomography angiography (CTA; the gold standard for PE diagnosis) and FOCUS. In nearly all cases, FOCUS — which involved assessment of right ventricular dilation, tricuspid regurgitation, septal flattening, McConnell sign, and tricuspid annular plane systolic excursion (TAPSE; <2.0 cm considered abnormal) — was performed prior to CTA. An abnormal result in any of these categories constituted a positive FOCUS examination.

A subgroup analysis of patients with HR ≥110 beats/min (irrespective of systolic blood pressure) was also conducted, and the sensitivity (primary outcome) and specificity (secondary outcome) of FOCUS for PE (compared with those of CTA for PE), were estimated for the entire cohort as well as for the subgroup. A blinded image review by an ultrasound-trained ED physician was used to determine interrater reliability.

The mean HR in the cohort was 114 beats/min, and 37 participants (27.2%) received PE diagnoses, based on CTA results. In the entire cohort, FOCUS had a sensitivity of 92% (95% CI, 78%-98%) and a specificity of 64% (95% CI, 53%-73%). The tricuspid annular plane systolic excursion (TAPSE) component of FOCUS was found to be the most sensitive for PE (88%), and the McConnell sign, the most specific (99%). In the subgroup of 98 patients (72.1%) with HR ≥110 beats/min, the sensitivity of FOCUS for detecting PE was 100% (95% CI, 88%-100%) and its specificity, 63% (95% CI, 51%-74%). The TAPSE component of FOCUS was the most sensitive for detecting PE (93%), and the McConnell sign was the most specific (100%). There was a high degree of interrater reliability for the determination by 2 different observations of the presence of PE based on FOCUS (𝜅 = 1.0; 95% CI, 0.31-1.0).

Study limitations include the use of a convenience sample, which may be associated with selection bias, its observational design, and missing FOCUS data for some patients that may have influenced sensitivity and specificity estimates.

“Our results suggest that FOCUS can be an important tool in the initial evaluation of ED patients with suspected PE and abnormal vital signs,” noted the authors.

This study was supported by the Society for Academic Emergency Medicine Academy of Emergency Ultrasound Research Grant.

Reference

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;26(11):1211-1220.