EUSER: Dx of Pulmonary Edema in pts w/ Acute Dyspnea: A Systematic Review/Meta-analysis

Al deeb M, Barbic S, Featherstone R, Dankoff J, Barbic D

Reference: Al deeb M, Barbic S, Featherstone R, Dankoff J, Barbic D. Point-of-care ultrasonography for the diagnosis of acute cardiogenic pulmonary edema in patients presenting with acute dyspnea: a systematic review and meta-analysis. Acad Emerg Med. 2014;21(8):843-52.

Why did they do this study?Drowning
To determine the sensitivity and specificity of US for diagnosing acute cardiogenic pulmonary edema

Bottom line: 
7 articles with n=1,075 identified.
Sensitivity = 94.1%, specificity = 92.4%. +LR 12.4, -LR 0.06
Gold standard = Final diagnosis.

Inclusion criteria:
Prospective cohort/ case-control studies.  Included inpatient and primary care. Only included those with undifferentiated acute dyspnea.

Where were the studies done?
-Two in the ED
-Two in the ICU
-Two in a hospital ward
-One in the prehospital setting

Who did the scans?
-All but one study used attendings as the scanners.  One study had mostly medical students performing the scans with some attending participation.

Gold standard:
Clinical diagnosis

With 7 articles included, sensitivity = 94.1%, specificity = 92.4%, +LR 12.4, -LR 0.06
They did a “cook analysis”, which basically measures if a study is such an outlier that it might affect the sum of the results.
3 studies were found that had an abnormal Cook distance: The study by Liteplo et al.(7)(Cook’s Distance = 1.22) and the two studies by Lichtenstein et al.6,19 (Cook’s Distance = 2.03 and 3.84). If you exclude these studies, sensitivity = 93.4% and specificity = 88.8%

What does it all mean?
B-lines are a great bedside imaging modality to differentiate ACPE from other causes of dyspnea. This study reported a +LR 12.4 and a -LR of 0.06 (A good +LR is >10, and a good -LR is <0.1).  This examination should be performed as early as possible, as b-lines start to go away with treatment (as evidenced in this article).  Although this meta-analysis doesn’t directly compare US to CXR directly, they quote 3 publications that report a sensitivity of 14% to 68% and a specificity of 53% to 96% for CXR. A final diagnosis from clinical follow-up was accepted as the reference standard.