The Effect of Dexmedetomidine as an Adjuvant for Lower Limb Nerve Blocks

Peripheral nerve block has been recommended as the technique for postoperative pain management because it provides equivalent analgesia but with fewer adverse effects than either systemic or epidural analgesia.

The use of clonidine, a partial α2 adrenoceptor agonist, has been reported to prolong the duration and analgesia in peripheral nerve blockade. Dexmedetomidine is a more selective and shorter-acting α2 adrenergic receptor.However, its use in femoral and common peroneal nerve blocks has not been described.

In this study, we investigated the effect of adding dexmedetomidine as additive in femoral and common peroneal nerve blocks for postoperative analgesia.

Patients, diagnosed as oromaxillofacial tumor and undergoing elective free fibular or anterolateral thigh flap reconstruction, were divided into two groups in a randomized, double-blind fashion. In Group Ropivacaine (Group R), nerve blocks were administered with 0.3% ropivacaine. In Group Ropivacaine + Dexmedetomidine (Group RD), nerve blocks were administered with 0.3% ropivacaine and 50 μg dexmedetomidine.The primary endpoints were the onset time and duration of sensory blocks. The secondary endpoints were heart rate, blood pressure, SpO2, sedation level, the duration of motor blocks.

Peripheral nerve block has been recommended as the technique for postoperative pain management because it provides equivalent analgesia but with fewer adverse effects than either systemic or epidural analgesia.

The use of clonidine, a partial α2 adrenoceptor agonist, has been reported to prolong the duration and analgesia in peripheral nerve blockade. Dexmedetomidine is a more selective and shorter-acting α2 adrenergic receptor.However, its use in femoral and common peroneal nerve blocks has not been described.

In this study, we investigated the effect of adding dexmedetomidine as additive in femoral and common peroneal nerve blocks for postoperative analgesia.

Patients, diagnosed as oromaxillofacial tumor and undergoing elective free fibular or anterolateral thigh flap reconstruction, were divided into two groups in a randomized, double-blind fashion. For patients with free fibular flaps harvested, femoral nerve block and common peroneal nerve with ropivacaine were administered. For patients with anterolateral thigh flaps harvested, femoral nerve block with ropivacaine was administered.In Group R, nerve blocks were administered with 0.3% ropivacaine. In Group RD, nerve blocks were administered with 0.3% ropivacaine and 50 μg dexmedetomidine.The primary endpoints were the onset time and duration of sensory blocks. The secondary endpoints were heart rate, blood pressure, pulse oxygen saturation (SpO2), sedation level, the duration of motor blocks.

Eligibility Criteria:
Inclusion Criteria:

* Diagnosis of oral and maxillofacial tumor.
* Undergoing microsurgical oromandibular reconstruction with free fibular flaps or anterolateral thigh flaps.
* Greater than 18 years old.
* Ability to understand and the willingness to sign a written informed consent document.

Exclusion Criteria:

* True allergy to local anesthetics or dexmedetomidine.
* History of chronic pain on opioids within the last 12 months.
* Specific mental health issues such as schizophrenia or bipolar disorder.
* Patients who are pregnant.