Efficacy of Ropivacaine With or Without Dexamethasone for Enhancing Extremity
Nerve Blocks
Chandramouli P. Iyer, MD 1, 2, 3; Larry Ross, MS 1; Girish Joshi, MD 2; Fima Lenkovsky, MD 1, 2; John Sum-Ping, MD 1,2

1 VA North Texas Healthcare System, Dallas, TX
2 University of Texas Southwestern Medical Center, Dallas, TX
3 Corresponding author.

INTRODUCTION. Prolonging interscalene brachial plexus block after surgery has demonstrated safe and effective pain relief (Chelly et al., 2001) with better quality of pain control, decreased side effects, and higher degree of patient satisfaction than patient-controlled IV analgesia with opioid drugs (Borgeat et al., 2000) making it the new “gold standard” for postoperative analgesia after open shoulder surgery (Casati, 2003). Additionally, ropivacaine has been shown as effective as bupivacaine for use in interscalene blocks, with ropivacaine having the further advantage of a lower potential for central nervous system and cardiovascular toxicity over bupivacaine (Casati, 2000). The addition of dexamethasone has been shown to enhance bupivacaine’s duration of action in nerve blocks (Kopacz et al., 2003; Curly et al., 1996); however, its usefulness with ropivacaine has not yet been demonstrated.
METHODS. Consented patients were randomized into the standard treatment group (40cc 0.5% ropivacaine) or the dexamethasone group (4mg dexamethasone plus 40cc 0.5% ropivacaine) prior to any study specific procedures. The site of injection was anesthetized (2% lidocaine) before nerve blocks were administered. Patients received either a femoral or interscalene nerve block by nerve stimulation technique. Once the block was completed, the patient was prepared for surgery and underwent general anesthesia. Following surgery, the patient was followed and asked to rate his/her pain scores on the VAS Scale and the time that sensation returned to the extremity.
RESULTS. There were no problems associated with the application of the nerve block in any of the patients (n=26). There was no significant difference between the two groups with respect to age (p=0.2254) or demographics. Additionally, there was no statistical significance between the 2 groups with respect to pain relief experienced during the recovery period (p=0.5645 to 0.8204). However, the time to return of extremity sensation was statistically significant between the two treatment groups (p=0.0139). Sensation returned to the placebo group (n=13) in 17.3 ± 7.1 hours while sensation returned to the
dexamethasone group (n=13) in 26.1 ± 9.6 hours. Further, within the placebo group, the length of femoral blocks (n=6) was significantly longer (22.6 ± 5.0 hours) than the interscalene blocks (n=7, 12.7 ± 4.8 hours, p=0.003). Within the dexamethasone group, there was also a significant difference between interscalene block length (n=9, 22.2 ± 5.9 hours) and femoral block length (n=4, 34.8 ± 11.6 hours, p=0.023). Lastly, dexamethasone was shown to enhance the length of both interscalene blocks (p=0.0037) and femoral
blocks (p=0.0538) when analyzed independently.
DISCUSSION. Here, we report that dexamethasone can significantly prolong analgesia of
extremity nerve blocks when used with ropivacaine without producing a significant motor block. Additionally, we found a 56% longer action of the blocks in lower limb blocks versus upper limb blocks in the dexamethasone group and a 78% longer action within the placebo group. Although there was no statistically significant difference in the VAS reported between the two groups, the results of this study demonstrate an effective treatment for outpatient procedures where a motor block is not desired. Further studies will attempt to determine whether this technique can decrease the use of narcotic pain medications and their undesired side effects.

TOP

© SOCIETY FOR AMBULATORY ANESTHESIA
520 N. Northwest Highway Park Ridge, Illinois 60068-2573
Tel: (847) 825-5586 Fax: (847) 825-5658
E-mail: samba@asahq.org