This study aims to compare two medications, dexmedetomidine and fentanyl, when used alongside a commonly used spinal anesthetic called bupivacaine in patients undergoing lower limb surgery. The main focus of the study is to see which combination causes fewer problems with urination after surgery - a condition known as postoperative urinary retention (POUR). POUR can lead to discomfort, delayed recovery, and a need for catheterization. Dexmedetomidine is a newer drug that may help reduce this problem compared to fentanyl, which is more commonly used but may increase the risk of urinary retention. This trial will help determine which medication combination provides better pain relief while reducing urinary side effects. The study is being conducted as a randomized, double-blind trial at a hospital in Nepal and will include 190 adult patients.
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Adults aged 18 to 60 years
Scheduled for elective lower limb surgery under spinal anesthesia
Classified as American Society of Anesthesiologists (ASA) physical status II or III
Minimum height of 150 cm (to ensure uniform drug volume)
Contraindications to spinal anesthesia (e.g., coagulopathy, infection at injection site, hemodynamic instability)
Known allergy or hypersensitivity to bupivacaine, fentanyl, or dexmedetomidine
Chronic pain conditions or long-term opioid use
Neurological, Cardiac, Renal, or uncontrolled diabetic conditions