Back pain after epidural anesthesia with chloroprocaine in volunteers: preliminary report.

The incidence, character and treatment of backache associated with epidural anesthesia (EA) using 3% chloroprocaine (2-CP, Nesacaine-MPF) were observed in ten volunteers undergoing a study of the effects of EA upon plasma catecholamines. Three levels of epidural analgesia were sequentially sought, T10, T4 and C8, in ascending order. Each block was allowed to fully dissipate prior to the next injection. For the first, second and third injections, 15-20 ml, 25-35 ml and 52-60 ml, respectively, of 3% 2-CP were injected via an epidural catheter. Mean total volume of 2-CP injected was 103 ml (range, 92-115 ml) over seven hours. Back pain was first reported after as little as 15 ml (mean +/- SEM, 24.0 +/- 3.9 ml; range, 15-45 ml). The pain was described as a dull ache deep in the lumbar back, ranging in severity from mild to severe. No profound spasm of the erector spinae muscles was observed. Mean verbal analog scale pain scores after regression of the first, second and third blocks were 2.2, 4.3 and 6.5, respectively. Epidural fentanyl (100-200 micrograms) was effective in providing rapid relief of the pain. Large doses or possibly repeated injections of epidural Nesacaine-MPF are associated with an increased incidence and severity of postanesthesia lumbar back pain.