Diagnostic accuracy of combined thoracic and cardiac sonography for the diagnosis of pulmonary embolism: A systematic review and meta-analysis

Objectives: Computed tomography pulmonary angiography (CTPA) is the diagnostic standard for pulmonary embolism (PE), but is unavailable in many low resource settings. We evaluated the evidence for point of care ultrasound as an alternative diagnostic. Methods: Using a PROSPERO-registered, protocol-driven strategy (https://www.crd.york.ac.uk/PROSPERO, ID = CRD42018099925), we searched MEDLINE, EMBASE, and CINHAL for observational and clinical trials of cardiopulmonary ultrasound (CPUS) for PE. We included English-language studies of adult patients with acute breathlessness, reported according to PRISMA guidelines published in the last two decades (January 2000 to February 2020). The primary outcome was diagnostic accuracy of CPUS compared to reference standard CTPA for detection of PE in acutely breathless adults. Results: We identified 260 unique publications of which twelve met all inclusion criteria. Of these, seven studies (N = 3872) were suitable for inclusion in our meta-analysis for diagnostic accuracy (two using CTPA and five using clinically derived diagnosis criterion). Meta-analysis of data demonstrated that using cardiopulmonary ultrasound (CPUS) was 91% sensitive and 81% specific for pulmonary embolism diagnosis compared to diagnostic standard CTPA. When compared to clinically derived diagnosis criterion, CPUS was 52% sensitive and 92% specific for PE diagnosis. We observed substantial heterogeneity across studies meeting inclusion criteria (I2 = 73.5%). Conclusions: Cardiopulmonary ultrasound may be useful in areas where CTPA is unavailable or unsuitable. Interpretation is limited by study heterogeneity. Further methodologically rigorous studies comparing CPUS and CTPA are important to inform clinical practice.