Why do thoracic epidurals fail? A literature review on thoracic epidural failure and catheter confirmation

Table 2 Studies discussing thoracic epidural failure

Ref.	Factors contributing to epidural failure
Porteous et al[5]	Equipment failure, such as debris in the catheter, incorrect catheter placement, epidural space characteristics and complexities
Motamed et al[8]	Anatomical variances, coiling and kinking of the catheter
Hamilton et al[9]	Changes in the position of epidural catheters associated with patient movement
Tran et al[11]	Primary failure of thoracic epidural analgesia in training centers
Yeager et al[14]	Malposition of epidural catheters
Tsui et al[15]	Incorrect catheter placement
Balki et al[16]	Incorrect catheter placement
Ghia et al[17]	Incorrect catheter placement
Lennox et al[18]	Incorrect catheter placement
Sánchez et al[20]	Incorrect catheter placement
Johnson et al[21]	Incorrect catheter placement