Comparison of the efficacy of intrathecal dexmedetomidine combined with bupivacaine versus bupivacaine alone on pain, shivering, nausea, and vomiting following lower limb orthopedic surgery: a randomized double-blind clinical trial in Nasiriyah, Iraq

Comparison of the efficacy of intrathecal dexmedetomidine combined with bupivacaine versus bupivacaine alone on pain, shivering, nausea, and vomiting following lower limb orthopedic surgery

This controlled, parallel-group, double-blinded, randomized phase 3 trial will include 80 patients. Randomization will use computer-generated block sequences with allocation concealment.

The study will be conducted at Al-Nasiriyah Teaching Hospital, Nasiriyah, Iraq. Participants will be randomly assigned to receive either intrathecal bupivacaine combined with 5 µg dexmedetomidine or intrathecal bupivacaine with saline. Patients and outcome assessors will be blinded to group allocation. Outcomes will be assessed during the first 24 hours after surgery.

Inclusion criteria: Adult patients aged 18-65 years, scheduled for elective lower-limb orthopedic surgery, ASA I–II, and eligible for spinal anesthesia; Exclusion criteria: Known hypersensitivity or contraindication to dexmedetomidine or bupivacaine, contraindications to spinal anesthesia, history of chronic pain syndromes or regular opioid use, significant cardiovascular disease, neurological or psychiatric disorders affecting pain assessment, and pregnancy or lactation.

All participants will receive standard perioperative care, and spinal anesthesia will be administered according to a standardized protocol. Participants will be randomly assigned to one of two study groups. Group A will receive intrathecal bupivacaine combined with dexmedetomidine, while Group B will receive intrathecal bupivacaine alone.

Primary outcome: Postoperative pain intensity. Secondary outcomes: severity of postoperative shivering, nausea and vomiting, time to first analgesic request, total analgesic consumption, requirement for rescue medications.

Participants will be randomly allocated in a 1:1 ratio to one of the two study groups using a computer-generated randomization sequence. Block randomization with a block size of four will be used to ensure balanced allocation between the groups. Allocation concealment will be achieved using sequentially numbered, opaque, sealed envelopes (SNOSE), which will be opened only after participants have been confirmed eligible for enrollment.

Patients, the anesthesiologist performing the spinal anesthesia, surgeons, outcome assessor, and data analyst will all be blinded to group allocation. Study drugs will be prepared by an independent anesthesiologist or nurse who is not involved in patient management, outcome assessment, or data collection. The study solutions will be prepared in identical syringes with equal volumes and labeled with coded identifiers. Outcome assessors will evaluate postoperative pain, shivering, nausea, and vomiting without knowledge of the assigned intervention. The allocation code will remain concealed until completion of data analysis unless unblinding is required for patient safety.

Only a part of patients' demographical data and main outcomes will be shared.

After the publishing of the results

Data will be available only for researchers working on academic and university associations.

Mention of study details and authors name

Dr. Morteza Nasiri: Department of Operating Room, School of Allied Medical Sciences, Tehran University of Medical Sciences, Tehran, Iran

Information will provide via the following email upon request. Mortezanasiri.or87@yahoo.com