A randomized controlled trial evaluating the hemodynamic impact of ultrasound-guided great auricular nerve block in middle ear microsurgery

Background: The peri-operative effectiveness of ultrasound-guided great auricular nerve block (GANB) in patients, especially in adult patients undergoing middle ear microsurgery remains unclear. We hypothesized that ultrasound-guided GANB would decrease the hemodynamic responsiveness to incision and opioid consumption in middle ear microsurgery as well as the post-operative analgesia requirement. Methods: Sixty patients undergoing middle ear microsurgery were randomized into two equal groups to receive either a GANB with 2 ml of 0.25% ropivacaine under ultrasound guidance (GANB group) or to receive a blank control intervention (without any performed injection) before general anesthesia inductions. The primary outcomes were hemodynamic changes of MAP (mean artery pressure) and HR (heart rate) to skin incision. The secondary endpoints were to determine the consumptions of propofol and remifentanil during the operation and the incidence of remedial analgesia 48 h post-operation to maintain VAS <= 3. Results: The MAP post incision in GANB group was significantly lower than that in control group (GANB group 93.83 +/- 11.72 mmHg vs. control group 100.87 +/- 12.65 mmHg,P = 0.029). The increases for MAP and HR post incision were also lower in GANB group (increment MAP GANB group 11.90 +/- 8.32 mmHg vs. control group 19.83 +/- 10.37 mmHg,P = 0.002; increment HR GANB group 3.67 +/- 5.30 beat min(- 1)vs. control group 8.23 +/- 8.56 beat min(- 1),P = 0.016). Remifentanil consumption was significantly decreased in GANB group (GANB group 401.55 +/- 100.51 mu g h(- 1)vs. control group 697.34 +/- 215.45 mu g h(- 1),P = 0.000). The incidence of remedial analgesia post-operation in GANB group (5/30) was significantly lower than that in control group (20/30,P = 0.000). Conclusion: Ultrasound-guided GANB decreases the hemodynamic responsiveness to incision and remifentanil consumption in middle ear microsurgery as well as the post-operative analgesia requirement.