Comparing the Safety and Effectiveness of Different Doses of Morphine Administered in Spinal Anethesia for Pain Relief After Hip Replacement Surgery

• Spinal Anesthesia (bupivacaine) (Procedure): Patients were positioned in sitting position on operating table, interspinous space was identified using anatomical landmarks (intercristal line) and palpation. Entire procedure was conducted with aseptic technique, puncture site was prepared with izopropyl alcohol solution. Skin was anesthetized with subcutaneous injection of 1% lidocaine. Spinal puncture was achieved using median or paramedian technique with 27G pencil-point spinal needle. After confirmation of free flow of cerebrospinal fluid 15 mg of 0,5% bupivacaine was administered intrathecaly. Block level was assessed by lack of sensation to alcohol swab in periumbilical area and complete motor block (Bromage 3).
• Postoperative pain management with acetaminophen (Drug): Postoperatively patients received 1,0g of paracetamol every 6 hours,
• PCA IV Oxycodone (Device): All patients were equipped with PCA capable syringe pump (Perfusor Space, B. Braun) with 40 milligrams of oxycodone. Care provider explained thoroughly how to operate the device and educated about possible adverse effects.
• Postoperative pain management with dexketoprofen (Drug): Postoperatively patients received 50mg of dexketoprofen intravenously every 8 hours.
• Postoperative pain management with metamizole (Drug): Postoperatively patients received 1,0g of metamizole intravenously every 6 hours.
• Preemptive Analgesics (Drug): After securing intravenous line each patient received preemptive analgesia with 1,0g paracetamol and 1,0g metamizole.
• Patient monitor (Device): Postoperatively each patient's vital signs were monitored continuously using patient monitor for 48 hours.

Primary outcomes

• Analgesic efficacy [48 hours postoperatively]: Analgesic efficacy defined as mean value of NRS (Numerical Rating Scale) at 4, 8, 12 ,24 and 48 hours postoperatively at rest and during rehabilitation/movement.
• Safety profile [48 hours postoperatively]: Frequency of adverse events including excessive sedation (defined as Richmond Agitation Sedation Score RASS≤-1), constipation, postoperative nausea and vomiting, pruritus and respiratory depression defined as sudden drop in respiration rate by ≥90% for ≥10 seconds or cyanosis.

Secondary outcomes

• Patient satisfaction [48 hours postoperatively]: Patient satisfaction with pain management measured with Likert scale. 1. Very satisfied. 2. Satisfied. 3. Neither satisfied nor dissatisfied. 4. Dissatisfied. 5. Very dissatisfied.
• Length of stay [Up to one week.]: Length of stay postoperatively.
• Time to rescue analgesia [48 hours postoperatively]: Amount of time before first bolus of oxycodone delivered by PCA syringe pump.
• Cumulative dose of oxycodone [48 hours postoperatively]: Cumulative dose of oxycodone over 48 hours postoperatively.

Sex: All, ages: 18 Years to 75 Years

Inclusion Criteria:

* Informed consent to participate in trial
* Qualification for total hip replacement surgery
* ASA physical status I-III
* BMI 19-30
* Lack of contraindications for drugs and interventions used in trial

Exclusion Criteria:

* Incapability to provide informed consent
* Contraindications for spinal anesthesia
* Preoperative chronic pain
* Chronic use of analgesics
* Obesity (BMI>30)
* Allergies and other contraindications for drugs used in trial
* Mental or physical incapability to operate PCA syringe pump