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

Table 4 Studies done on confirming thoracic epidural catheter position

Ref.	Techniques for confirming catheter position
Teoh et al[10]	Surface anatomy as a guide to vertebral level for thoracic epidural placement
Yokoyama et al[13]	Evaluation of contrast medium distribution and blockade extent during epidural anesthesia
Yeager et al[14]	Fluoroscopy-assisted epidural catheter placement
Tsui et al[15]	Confirmation of catheter placement using nerve stimulation
Balki et al[16]	Epidural electrical stimulation test
Ghia et al[17]	Confirmation of catheter position using epidural pressure waveform and computed tomography catheter gram
Lennox et al[18]	Use of pulsatile pressure waveform as a marker for confirming the location of the thoracic epidural space
Sánchez et al[20]	Radiological visualization of catheters placed in the epidural space