Effect of Nerve Block Versus General Anaesthesia for Distal Radial Fracture Surgery

Effect of Infraclavicular Nerve Block Versus General Anaesthesia for Acute Postoperative Pain After Distal Radial Fracture Surgery

This study aims to investigate whether infraclavicular nerve block improves acute postoperative pain after distal radial fracture surgery.

A single blinded randomized control trial will be performed to compare regional anaesthesia with single shot infraclavicular nerve block versus general anaesthesia.

The primary outcome was postoperative NRS pain score (0-10) with movement at 24 hours after surgery. No suitable references for postoperative NRS pain scores at 24 hours that could be used for sample size calculation was found. Based on a previous study on RA versus GA for hand surgery, the standard deviation estimate of the treatments for sample size calculation was 2.86. To detect a difference in NRS pain score of 2.4/10 at a significance level of 0.05 and a power of 0.80, the minimum number of patients required per group was 23. A difference of 2.4 in NRS pain score was chosen because this has been shown to correspond to 'much improvement' in pain relief, which is clinically significant. To take into account for possible dropouts, 26 patients were recruited into each group.

Patients will be approached in the general ward before operation. The aims of the study and need for follow up assessment would be explained and patient will be recruited only if s/he agrees. After agreeing to join the study, patients will be randomly allocated to one of two groups: 1) General anaesthesia (GA) 2) Regional Anaesthesia with infraclavicular block (RA). Outcomes of patients in receiving general anaesthesia (GA) will be compared with patients receiving infraclavicular nerve block (RA).

Data Analysis Intention-to-treat will be used. Patients will remain in their initial designated groups for data analysis even if there is a change in surgical or anaesthetic/analgesic management, as long as they are undergoing distal radial fracture surgery not involving another operative site (eg bone graft). Patients in the RA group who required conversion to general anaesthesia due to inadequate infraclavicular block would remain in the RA group for data analysis.

Statistical methods used:

• Incidence of chronic post surgical pain: Chi-Square test
• NRS pain scores at 3 and 6 months after surgery: Mann-Whitney test to look at difference in mean pain scores between two groups
• duration of anaesthetic, analgesic and surgical procedures, time to extubation, cumulative opioid consumption, dose and frequency of rescue analgesic used, time to food intake and ambulation, time to discharge, patient satisfaction: Kruskal-Wallis test
• Acute NRS pain scores over 48 hours: Postoperative NRS pain scores were expressed in median (interquartile range) and analyzed using Mann-Whitney U test with post-hoc multiple comparisons using Bonferroni procedure
• Patient demographic data: One way ANOVA and chi-square test.
• Intraoperative vital signs, HRQOL, HADS, DASH-HKPWH: Repeated measures ANOVA (with Bonferroni correction when appropriate)
• Side effects and postoperative complications: Chi Square test
• When a significant result is obtained, t-test or Mann-Whitney test for numerical values and Chi-square test for categorical data will be applied for post hoc pairwise comparisons.

Inclusion Criteria:

• ASA I-III
• Age 18-80 years old
• Scheduled for distal radial fracture surgery (ie open reduction and internal fixation)

Exclusion Criteria:

• Surgery involving more than distal radial fracture of the affected arm
• Known allergy to opioids (including the weak opioids tramadol and dihydrocodeine), local anaesthetic drugs, non-steroidal anti-inflammatory drugs (NSAIDS) including COX-2 inhibitors, paracetamol.
• History of chronic pain
• Alcohol or drug abuse
• Impaired renal function, defined as preoperative serum creatinine level over 120 µmol/L
• Patients with liver dysfunction (Plasma bilirubin over 34 mol/L, INR >/=1.7, ALT and AST over 100U/L)
• Pre-existing neurological or muscular disorders
• Psychiatric illness
• Impaired or retarded mental state
• Not self-ambulatory before operation
• Pregnancy
• Local infection
• Patient refusal