A Randomized Two-parallel Group Controlled Trial Comparing the Effects of 20mg Parecoxib as an Adjunct to 0.75% Ropivacaine in Ultrasound-guided Supraclavicular Block for Upper Limb Surgery

Brachial plexus block (BPB) has enjoyed ubiquitous popularity for upper limb surgeries.There are a few common techniques for BPB and one of the most frequently-utilised one is supraclavicular BPB since it provides a quick-onset, efficient, safe and dense anaesthesia for surgical procedures that involve the proximal mid-humerus down to the distal hand. At present, most BPB techniques have been widely performed under ultrasound guidance to enhance the BPB's success rate and lessen its complications.

There are several adjunct drugs that can be mixed with local anaesthetics agents (e.g. ropivacaine) to speed up the onset and prolong the duration of BPB and minimise the risk of local-anaesthestic(LA)-associated overdose and toxicity. Parecoxib, a prodrug of valdecoxib, is an ideal choice for such combination due to its excellent toxicity profile.It acts by inhibiting the function of the constitutive COX-2, an isoform of cyclooxygenase (COX), resulting in the diminution of prostaglandin H2 and E2 synthesis. Consequently, this diminishes nociception by reducing sensory neuron's excitability and bradykinin-associated hyperalgesia.

So far, there is only one study which investigates the efficacy of parecoxib as an adjunct to ropivacaine in patients requiring BPB performed via axillary approach for their upper limb surgeries. However, adjunct parecoxib's efficacy in BPB performed via supraclavicular approach is still not fully scrutinised. Therefore, this clinical trial endeavours to evaluate the efficacy of adjunct parecoxib in supraclavicular BPB.

This is a randomised two parallel groups active-controlled single centre double-blind (participant and outcome assessors) clinical trial comparing the effects of parecoxib as an adjunct to ropivacaine. This trial protocol received the approval from University of Science Malaysia's Human Ethics Research Committee (HERC) on the 20th June 2016 and all participants had provided written informed consent for study participation.

The study participants were then block-randomized using a block size of 4 with a balanced 1:1 allotment ratio without any covariate stratification. The block randomization was performed using permuted block design, with the random numbers generated by a random number generator package in Stata 9.0. This was performed by an independent third party statistician. To ensure selection bias was prevented, the allocation sequence was kept inside a password-protected STATA 9.0 file which was only accessible to the independent third-party statistician. The sequence of treatment allotment was only revealed after a study participant was properly recruited and subsequently randomised to treatment allotment. To prevent ascertainment and performance bias, the study participants and the independent assessors (2nd medical officers) were shielded from the knowledge of the type of intervention received. However, the intervention was administered by the primary investigator who was not blinded to the kind of intervention received by a study participant.