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

Table 3 Techniques for confirming thoracic epidural catheter position

Technique	Description	Advantages	Disadvantages
Electrophysiological stimulation	Connecting nerve stimulator to catheter	High sensitivity and effectiveness in confirming position	Requires specialized adaptor
	Applying current and assessing motor response	Correlation with adequate postoperative analgesia	Discomfort to awake patient
	Bilateral stimulation indicates proximity to nerve root		Does not give information on local spread
	Limb or truncal response indicates epidural space
Epidural catheter waveform	Connecting catheter to pressure transducer	Simple technique using readily available equipment	Does not provide information about catheter level or injectate spread
	Confirming epidural space when pulsatile waveform is obtained
Contrast epidurography	Taking X-ray after injection of radio-opaque contrast	Confirms epidural position and assesses catheter level and spread pattern	Involves X-ray, may not be suitable for all patients
	Assessing contrast spread and catheter placement	Identifies anatomical variances and coiling/kinking	Time-consuming. Required training for epiduralgram interpretation
	Evaluating bilateral spread and vertebral levels		Risk of transiently raising spinal cord pressure with large volumes