Ropivacaine 0.4% iontophoresis versus continuous catheter infusion after iliac crest bone grafting in lumbar spine surgery

Background
Iliac crest (IC) pain accompanies IC grafting in spine surgery. The study evaluates the effectiveness of ropivacaine 0.4% iliac crest iontophoresis as compared to infusion through an IC catheter.
Methods
Thirty patients, 10 in each group, undergoing lumbar spine surgery had an intraoperative epidural block performed and initiated with 20 ml ropivacaine, 0.5% (100 mg) at termination of surgery and after 6 h maintained for 48 h (t48) at 10 ml/h with ropivacaine, 0.2%. Thirty millilitres NaCl, 0.9% (Group I “placebo group” and Group II “ropivacaine iontophoresis group”) or 30 ml ropivacaine, 0.4% (Group III “ropivacaine IC catheter group”) was also administered via an intraoperatively placed IC catheter. At t0, and for 48 h, 5 ml/h ropivacaine, 0.4% was administered via the IC catheter in Group III. In Group II, 30 ml ropivacaine, 0.4% iontophoresis was done using iontocare iontophoresis device. At t0 and for 48 h, 5 ml 0.4% ropivacaine iontophoresis was done at iliac crest site every hour using the iontocare device in Group II. Any further pain was controlled using intravenous morphine 0.1% in 5 mg increments. Pain assessment scores at IC site and at surgical site were evaluated at rest and at motion every 8 h for 48 h and after 4 m. Unbound and total plasma ropivacaine, morphine consumption, and patient satisfaction were evaluated.
Results
At IC site, significant lower pain scores were elucidated in Groups II and III as compared to Group I at rest and at motion in the initial 48 h and at motion after 4 m. Plasma unbound ropivacaine was higher significantly in Group III at t48 when compared with Group I. Morphine consumption was lower significantly in Groups II and III at 24 and at 48 h when compared with Group I.
Conclusions
Ropivacaine IC iontophoresis provides safe effective analgesia for the initial 48 h and after 4 m.