Heart rate, a poor predictor of Pulmonary Embolism

Abstract

Objective: To determine if there is a significant difference in vital signs between patients with confirmed and excluded pulmonary embolism (PE) throughout their Emergency Department presentation. Methods: We conducted a retrospective cohort study with patients presenting with suspected PE to Monash Health Emergency Departments between July 2014 and July 2019. Vital signs were compared between patients with confirmed or excluded PE as determined by imaging (CTPA or VQ). Vital signs were compared at three unique data points: initial, minimum, and maximum values. Results: 3549 patients met inclusion criteria, 922 with confirmed PE and 2627 with excluded PE based on CTPA or VQ. Patients with PE had significant elevations in mean respiratory rates, systolic blood pressures and reduced oxygen saturations compared to patients without PE. Heart rate was not significantly different at initial and maximum datapoints. Conclusion: Vital signs were demonstrated to be poor predictors of acute PE. Receiver operating characteristic curve analysis suggests that heart rate has poor discriminative power. AUC values for heart rate were: 0.516 (initial), 0.549 (maximum) and 0.519 (minimum). Furthermore, 95% of patients with confirmed PE did not exceed heart rates of 100 BPM during presentation to Emergency. The utility of elevated heart rate and other vital signs in predicting PE were not substantiated in this study.