A systematic review of the diagnostic accuracy of epidural wave form analysis to identify the epidural space in surgical and labor patients.

Epidural failure due to misidentification of the epidural space is not uncommon. Epidural wave form analysis has been suggested to identify the epidural space. A systematic literature search (Medline, Epub, Embase.com (Embase plus Medline), Cochrane Central, Web of Science, and Google Scholar) was performed to identify studies comparing epidural wave form analysis (index test) to epidural analgesia (reference test). Eight studies (3901 patients) were retrieved that provided data on diagnostic accuracy. These studies had a low risk of bias and of applicability concerns, as assessed by the quality assessment of diagnostic accuracy studies (QUADAS-2) tool. One study did not observe an epidural wave form in parturients, a finding that was not corroborated in another study. Because the reference test was different across the studies we decided not aggregate the data. The sensitivity values of the individual studies varied between 0.81 and 1.00, for the specificity values between 0.42 and 1.00 were found. Our study suggests that epidural wave form analysis is a reliable method for identification of the epidural space that could become a useful adjunct especially in anticipated difficult catheter placements or in teaching situations. Further research is warranted to define the role of epidural wave form analysis in pregnant women.