Combined epidural/spinal anaesthesia: needle-through-needle or separate spaces?

Background and objective: This prospective, randomized and blinded study compared the performance of a new needle-through-needle (NTN) kit (Epistar(R); Medimex, Germany) with the double-space technique for providing combined spinal epidural anaesthesia during Caesarean section. Methods: Following local Ethics Committee approval and patient consent, 200 females were randomized to receive combined spinal epidural anaesthesia by the double-space (n = 100) or NTN (n = 100) technique. The frequency with which the intrathecal component could achieve a T5 block to touch for Caesarean section without the need for epidural augmentation or an alternative technique was determined. The time from start of procedure to achieving a block height to T5 was recorded. Pain and backache at insertion, and at 24 h follow-up were recorded using a visual analogue scale. To remove any bias due to posture, 50% of each group were further randomized to receive their block in the sitting or in the left lateral position. To evaluate improvement of performance over time the success in the first 100 study patients were compared to the success in the second 100. Results: A successful block to T5 with the double-space and NTN techniques were 80 vs. 54, odds ratio 0.29. Failure to enter the intrathecal space once the epidural space had been located occurred in 29 patients in the NTN group. Time to readiness for surgery was 15 min (95% confidence interval (Cl): 12.7-17.4) and 12.9 min (95% CI: 11.5-14.3) for the double-space and NTN techniques, respectively. The median (interquartile range) visual analogue scores for discomfort at insertion were 30 (12.5-51.5) and 32 (12.75-60) and for postoperative backache 0 (0-10) and 0 (0-10.75) in the double-space and NTN groups, respectively. The number of epidural augmentations was similar in both the groups and posture made no difference. There was a tendency to increased success in the second half of the study. Conclusion: The double-space technique had a greater success rate than the NTN technique.