A Randomized Observer-Blinded Controlled Trial to Compare Pre-Emptive with Postoperative Ultrasound-Guided Mandibular Nerve Block for Postoperative Analgesia in Mandibular Fracture Surgeries.

BACKGROUND AND AIMS

Ultrasound-guided (UG) mandibular nerve block is effective for providing postoperative analgesia in mandibular fracture surgeries. The pre-emptive nerve blockade prolongs the duration of postoperative analgesia and reduces the consumption of intraoperative opioids. The aim of this prospective, randomized, single-blinded study was to compare the efficacy of pre-emptive and postoperative UG mandibular nerve block for postoperative analgesia in mandibular fracture surgeries.

METHODS

Sixty patients scheduled for unilateral mandibular fracture surgeries were randomly divided into two groups by computer-generated random numbers and sealed envelope method: Group A received UG mandibular nerve block before surgical incision and group B received after surgery with ropivacaine 0.5% 10mL. The second anesthesiologist, who was blinded to the group involved, monitored the patient. The patients as well as the statistician were also blinded. The patients were started on patient-controlled analgesia (PCA) morphine with bolus 1mg and a lockout interval of 10min. The morphine consumption for 24h was recorded. The pain was assessed by the VAS score. The additional intraoperative fentanyl consumption and time for a request for rescue analgesic were recorded.

RESULTS

The total morphine consumption was reduced in group A (4.566±0.717mg) than group B (5.93±0.876mg) with a p-value of <0.0001. The time for a request for rescue analgesic was also prolonged in group A (794.08±89.561min) than group B (505.333±3.159min). In group A, only four patients required an additional dose of fentanyl as against 11 patients in group B. The heart rate was also lower in group A 30min after the administration of the block and persisted for two hours intraoperatively.

CONCLUSION

Pre-emptive ultrasound-guided mandibular nerve block reduces morphine consumption, prolongs the time for a request for rescue analgesic, reduces intraoperative fentanyl consumption, provides better control of intraoperative heart rate, and better pain scores postoperatively when compared to the postoperative mandibular nerve block.