Patients undergoing total knee arthroplasty (TKA) under spinal anesthesia often request sedation to alleviate anxiety. Dexmedetomidine may be ideally suited to provide sedation during surgery as it offers sedation and analgesia without causing significant respiratory depression. Furthermore, dexmedetomidine has beneficial synergistic interactions with opioids and sedative drugs.~Altogether 80 patients scheduled for elective unilateral TKA under spinal anesthesia will be included in the prospective, randomized and controlled parallel-group study. Patients will be randomized into two groups, forty patients in each group. All patients will receive preoperatively 1000 mg of oral paracetamol as premedication. One group receives a single bolus dose of intranasal 1 ug/kg dexmedetomidine (DEX group) and the other group receives euvolemic dose (10 µL/kg) of saline (PLACEBO-group).~Spinal anesthesia will be performed using bupivacaine (5 mg/mL) using 2.0-2.5 mL dose, the amount depending on the clinical judgement of the anesthesiologist responsible for the patient. If patient needs additional analgesic after spinal anesthesia, 50 µg dose of intravenous fentanyl or 3-5 mg of intravenous midazolam may be administered intraoperatively.~Postoperative pain management in the surgical ward includes oral paracetamol 1000 mg every 8 hours, and from the first postoperative day onwards patients receive oral naproxen/esomeprazole 500/20 mg twice a day. Oral oxycodone (5-10 mg) will be used, if the pain (measured with visual rating scale, VAS, min 0, max 100, higher scores mean worse outcome) is moderate or intense (VAS>30) after paracetamol and naproxen.~Postoperative pain (VAS) and opioid consumption (mg) will be measured and analysed together with intraoperative sedative used (mg, midazolam and/or fentanyl allowed).
This study aims to find out if preoperatively given dexmedetomidine is effective analgesic adjuvant for treating postoperative pain in patients undergoing elective total knee arthroplasty (TKA). Another aim is to determine if premedication with intranasal dexmedetomidine could provide sufficient sedation to alleviate anxiety during TKA.