An analysis of postoperative epidural analgesia failure by computed tomography epidurography

In this prospective study involving 125 patients, we analyzed epidural analgesia failure after major abdominal surgery using computed tomography (CT) epidurographies to compare the incidence of dislodgement of epidural catheters and leakage of solution from the epidural space between two groups of patients: patients with successful or failed epidural analgesia. Our hypothesis was that the incidence of dislodgement and leakage should be low when epidural analgesia is successful. A thoracic epidural catheter was inserted before general anesthesia and secured by subcutaneous tunneling. Bupivacaine (0.25%) was administered during surgery followed by continuous epidural analgesia with 0.125% bupivacaine (10 mL/h) and morphine (0.25 mg/h) for 48 h. Failure was defined as a visual analog scale pain score at rest more than 30 mm and/or interruption of epidural analgesia before 48 h for any reason. When failure was not due to unintentionally withdrawn, kinked catheters or adverse events (n = 11), a CT scan with contrast injection was performed. Control CT scans were also performed in patients with adequate analgesia (i.e., the success group). The incidence of failure was 24.8% (n = 31). CT scans in the failure group (n = 20) showed seven patients with catheters outside the epidural space, nine with normal distribution, one with unilateral spread, and three with leakage of solution outside the epidural space. In the success group, CT scans (n = 19) showed 11 patients with normal distribution, five with unilateral spread, and three with leakage. We conclude that the major cause of epidural analgesia failure was dislodgment of the catheter. CT scans were mostly useful for detecting leakage of injectate, which may be the early phase of dislodgment.