ACADEMIC EMERGENCY MEDICINE 2012; 19:11–17 © 2012 by the Society for Academic Emergency Medicine
Objectives: In a patient with symptoms of pulmonary embolism (PE), the presence of an elevated pulse, respiratory rate, shock index, or decreased pulse oximetry increases pretest probability of PE. The objective of this study was to evaluate if normalization of an initially abnormal vital sign can be used as evidence to lower the suspicion for PE.
Methods: This was a prospective, noninterventional, single-center study of diagnostic accuracy conducted on adults presenting to an academic emergency department (ED), with at least one predefined symptom or sign of PE and one risk factor for PE. Clinical data, including the first four sets of vital signs, were recorded while the patient was in the ED. All patients underwent computed tomography pulmonary angiography (CTPA) and had 45-day follow-up as criterion standards. Diagnostic accuracy of each vital sign (pulse rate, respiratory rate, shock index, pulse oximetry) at each time was examined by the area under the receiver operating characteristic curve (AUC).
Results: A total of 192 were enrolled, including 35 (18%) with PE. All patients had vital signs at triage, and 174 (91%), 135 (70%), and 106 (55%) had second to fourth sets of vital signs obtained, respectively. The initial pulse oximetry reading had the highest AUC (0.63, 95% confidence interval [CI] = 0.50 to 0.76) for predicting PE, and no other vital sign at any point had an AUC over 0.60. Among patients with an abnormal pulse rate, respiratory rate, shock index, or pulse oximetry at triage that subsequently normalized, the prevalences of PE were 18, 14, 19, and 33%, respectively.
Conclusions: Clinicians should not use the observation of normalized vital signs as a reason to forego objective testing for symptomatic patients with a risk factor for PE.