Effectiveness of preoperative thoracic epidural testing strategies: a retrospective comparison of three commonly used testing methods.

Purpose: Thoracic epidural analgesia (TEA) is a well stablished technique for pain management in major thoracic and abdominal surgeries; however, it has considerable failure rates. Local anesthetic (LA) administration and subsequent assessment of sensory block through physical examination (e.g., decreased temperature perception determined via an LA temperature dissociation test [LATDT]) has been the historical standard for evaluation of thoracic epidural placement. Nevertheless, newer methods to objectively evaluate successful placement have recently been developed, e.g., the epidural electrical stimulation test (EEST) and epidural pressure waveform analysis (EWA). The purpose of this study was to evaluate the effectiveness of preoperative TEA catheter testing (LATDT, EEST, and EWA) on reducing TEA failure.

Methods: After obtaining an institutional research ethics board approval for a retrospective study, we conducted a single-institution retrospective review on all TEAs performed between January 2016 and December 2021. Patients were assigned to one of four groups based on the performed test method to verify the placement of the TEA catheter: no test, LATDT, EEST, and EWA. A TEA was deemed successful if it provided bilateral dermatomal sensory block to ice test in the postoperative period, and was used for patient analgesia for at least 24 hr.

Results: One thousand two hundred and forty-one patients submitted to preoperative TEA were included. Twenty-eight patients were excluded. Tested and untested epidurals had failure rates of 3.8% (95% confidence interval [CI], 1.8 to 6.2) and 11.5% (95% CI, 5.2 to 17.1), respectively (P < 0.001).

Conclusion: Objective preoperative testing after placement of thoracic epidurals was associated with a reduction in failure rates.