Anesthesia & Clinical Research
Open Access

Abstract

Dexamethasone as an Additive to Low Volume Interscalene Plexus Blockade: A Randomized Controlled Study

Andreas Liedler, Benedikt Sattler, Ingo Zorn, Christian Fohringer, Sabine Ottenschlager, Herbert Steininger and Christoph Hormann

Background: Interscalene Blockade is widely used to ensure analgesia in surgery involving the shoulder. Both i.v. and perineural dexamethasone seem to be able to prolong the block duration and can therefore be used to reduce the use of analgesics. However most of the studies focusing on dexamethasone as an additive use large volumes (20 ml) of local anesthetic agent. Larger volumes may be associated with a higher rate of complications. Therefore the hypothesis of this study is to prove whether dexamethasone is also able to prolong the pain free time when given together with a low volume (10 ml) of anesthetic agent. Methods: The study was conducted as a prospective, double-blinded randomized trial. Patients with arthroscopic surgery of the shoulder were included in our study. The blockade was performed using ultrasound guidance to ensure a low rate of block failure. We used eight milligrams of dexamethasone (free of preservative) and ten millilitres of ropivacaine in a concentration of 0.75%. The primary endpoint was analgesic duration defined as the time between performance of the block and first analgesic request. The primary variable was analyzed using a log rank test. Secondary endpoints were the assessment of the pain at the surgical site ten hours after operation at rest and movement. Results: 104 patients were included in our study. The ethics committee of Lower Austria approved the study and patients signed an informed consent in order to participate in our study. During the study five patients were excluded due to block failure. Using a log-rank test, we observed a prolongation of pain free time of 310 minutes. The analysis of the NRS-score ten hours after surgery yielded a significant difference between the control and active group at rest. Unexpectedly the NRS – score at movement does not differ between the control and active group. Conclusion: Dexamethasone used in a low volume plexus brachialis blockade is able to prolong the pain free time.