Role of Transthoracic Lung Ultrasonography in the Diagnosis of Pulmonary Embolism: A Systematic Review and Meta-Analysis

Background
Pulmonary embolism (PE) is a potentially life-threatening condition. Although computed tomography pulmonary angiography (CTPA) is the reference standard for diagnosis, its early diagnosis remains a challenge, and the concerns about the radiation exposures further limit the general use of CTPA. The primary aim of this meta-analysis was to evaluate the overall diagnostic accuracy of transthoracic lung ultrasound (TLS) in the diagnosis of PE.
Methods
PubMed, Web of science, OvidSP, ProQuest, EBSCO, Cochrane Library and Clinicaltrial.gov were searched systematically. The quality of included studies was assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 tool. The sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR) and hierarchical summary receiver operating characteristic (HSROC) curves were used to examine the TS performance. The Bayes analysis was used to calculate the post-test probability of PE. Publication bias was assessed with Deeks funnel plot.
Results
The results indicated that the sensitivity, specificity, PLR and NLR were 0.85 (95% confidence interval (CI), 0.78 to 0.90), and 0.83 (95% CI, 0.73 to 0.90). And the DOR and HSROC were 28.82 (95% CI, 17.60 to 47.21), 0.91(95% CI, 0.88, 0.93).
Conclusions
The present meta-analysis suggested that transthoracic lung ultrasonography is helpful in diagnosing pulmonary embolism. Although the application of transthoracic lung ultrasound may change some patients’ diagnostic processes, it is inappropriate to generally use transthoracic ultrasonography in diagnosing pulmonary embolism currently.

背景
肺栓塞（Pulmonary embolism, PE）是一种可能危及生命的疾病。尽管计算机断层扫描肺血管造影（computed tomography pulmonary angiography, CTPA）是肺栓塞诊断的金标准，但其早期诊断仍面临挑战，且辐射暴露相关顾虑进一步限制了CTPA的广泛应用。本荟萃分析的主要目的是评估经胸肺超声（transthoracic lung ultrasound, TLS）诊断肺栓塞的整体诊断准确性。

方法
系统检索PubMed、Web of Science、OvidSP、ProQuest、EBSCO、Cochrane Library及Clinicaltrial.gov数据库。采用诊断准确性研究质量评价工具2（Quality Assessment of Diagnostic Accuracy Studies-2 tool）对纳入研究的质量进行评价。通过灵敏度、特异度、阳性似然比（positive likelihood ratio, PLR）、阴性似然比（negative likelihood ratio, NLR）、诊断比值比（diagnostic odds ratio, DOR）及分层综合受试者工作特征（hierarchical summary receiver operating characteristic, HSROC）曲线分析经胸肺超声的诊断性能。采用贝叶斯分析计算肺栓塞的验后概率。使用Deeks漏斗图评估发表偏倚。

结果
结果显示，经胸肺超声的灵敏度、特异度、阳性似然比及阴性似然比分别为0.85（95%置信区间（confidence interval, CI）：0.78~0.90）与0.83（95%CI：0.73~0.90）；其诊断比值比及分层综合受试者工作特征曲线参数分别为28.82（95%CI：17.60~47.21）与0.91（95%CI：0.88~0.93）。

结论
本荟萃分析结果表明，经胸肺超声有助于肺栓塞的诊断。尽管经胸肺超声的应用可能改变部分患者的诊断流程，但目前尚不适合将经胸肺超声普遍用于肺栓塞的诊断。