Efficacy and Safety Study of Dexmedetomidine as an Additive to Local Anesthetics in Shoulder Surgery

• Efficacy of dexmedetomidine in perineural application [ Time Frame: 24 hrs ] [ Designated as safety issue: No ]
  The time until the patient describes the blockade as completely gone will be analysed and compared between the groups.
  
  
• Safety of dexmedetomidine in perineural application [ Time Frame: 30 days ] [ Designated as safety issue: Yes ]
  Any serious and/or unexpected adverse (AE) events will be assessed on an individual basis by the Principal Investigator and the DSMB. After the first twenty subjects (10 controls and 10 receiving study agent) have completed the study, the data will be reviewed. Provided the DSMB determines the initial safety is established, enrollment will proceed until a total of 62 subjects (31 subjects/group) have been accrued.
  
  

• Analgesia [ Time Frame: first 24-48 hrs ] [ Designated as safety issue: No ]
  Analgesia will be assessed based on postoperative pain scores
  
  
• Onset of sensory blockade [ Time Frame: every 3 minutes for the first 21 minutes ] [ Designated as safety issue: No ]
  The subject's sensory function will be measured every 2 minutes for the first 20 minutes, until the loss of sensory function in the dermal distribution of the shoulder.
  
  
• Duration of motor blockade [ Time Frame: first 24-48 hrs ] [ Designated as safety issue: No ]
  The time to return of motor strength will be recorded in the subject's postoperative course.
  
  
• Opioid-induced side effects [ Time Frame: first 24-48 hrs ] [ Designated as safety issue: No ]
  Opioid-induced side effects will be recorded in the subject's postoperative course.
  
  

Peripheral nerve blocks are used throughout the world in lieu of general anesthesia and, more commonly, to provide analgesia and opioid sparing in the postoperative course. Long acting local anesthetics, such as ropivacaine, can provide analgesia for 11.5 ± 5 hours. This leads to many patients reporting their first pain in the evening and nighttime hours when access to healthcare providers and support is most limited. A number of additives to local anesthetics have been studied in humans with limited success. Recent work by a group in Michigan found a dose dependent increase in the duration of analgesia to a thermal stimulus when dexmedetomidine was added to ropivacaine for sciatic nerve blocks in rat.

The goal of the study is to investigate the safety and efficacy of dexmedetomidine added to ropivacaine for interscalene brachial plexus nerve block for shoulder surgery in humans. Provided the initial safety can be established, the trial will continue to evaluate secondary goals including the duration of analgesia, onset of sensory and motor blockade, and opioid-induced side effects. Tertiary outcomes will include subject satisfaction.