Abstract
The authors evaluated the relation between radiographic and analgesic spread during epidural block. An epidural catheter was inserted in 90 patients. The analgesic area was determined by pinprick after a 5-ml injection of 1.5% lidocaine, and epidurography was performed after a 5-ml injection of 240 mgI·ml -1 iotrolan. Patients were assigned to three groups according to catheter tip position (group C: C-T4; group T: T5-T10; group L: T11-L) , and patterns of spread were compared. The total radiographic spread correlated well with analgesic spread (right side: Y=0.81X+0.16, r=0.92, p<0.01; left side: Y=0.78X+0.46, r=0.91, p<0.01) . The mean distance between the predicted catheter tip and radiographically determined positions was 1.0 +/- 0.8 segments: the value in group T was significantly larger than that in groups C (p<0.05) and L (p<0.01) . Although the correlation of radiographic spread with age was statistically significant (r=0.39, p<0.01) , great individual variation in spreading pattern was seen in all groups. Epidurography is useful for indicating epidural catheter position and can help to predict the exact dermatomal distribution of analgesic block.
