Combined spinal-epidural techniques.

The combined spinal-epidural technique has been used increasingly over the last decade. Combined spinal-epidural may achieve rapid onset, profound regional blockade with the facility to modify or prolong the block. A variety of techniques and devices have been proposed. The technique cannot be considered simply as an isolated spinal block followed by an isolated epidural block as combining the techniques may alter each block. This review concentrates on technical and procedural aspects of combined spinal-epidural. Needle-through-needle, separate-needle and combined-needle techniques are described and modifications discussed. Failure rates and causes are reviewed. The problems of performing a spinal block before epidural blockade (potential for unrecognised placement of an epidural catheter, inability to detect paraesthesia during epidural placement, difficulty in testing the epidural, delay in positioning the patient) are described and evaluated. Problems of performing spinal block after epidural blockade (risk of catheter or spinal needle damage) are considered. Mechanisms of modification of spinal blockade by subsequent epidural drug administration are discussed. The review considers choice of technique, needle type, patient positioning and paramedian vs. midline approach. Finally, complications associated with combined spinal-epidural are reviewed.