Comparison Between Dexamethasone and Morphine as an Adjuvant to Bupivacaine for Post-operative Analgesia

Approval from Ethical Committee of Faculty of Medicine University of Indonesia was acquired prior conducting the study. Subjects were given informed consent before enrolling the study and randomized into two groups. Intravenous (IV) cannula with Ringer Lactate fluid, non-invasive blood pressure monitor, electrocardiogram (ECG) and pulse-oxymetry were set on the subjects in the operation room. Epidural catheter was inserted (4 cm depth inside the epidural space) with 1,5-2 mg IV midazolam and 50 mcg IV fentanyl as premedication. The catheter insertion was confirmed with vacuum aspiration and negative test-dose. General anesthesia induction was done by fentanyl 2 mcg/kg, propofol 2 mg/kg, and atracurium 0,5 mg/kg. Maintenance was done by sevoflurane 2vol%, fentanyl and atracurium. Surgery starts without intraoperative epidural regimen. Surgery duration, blood pressure, heart rate, respiratory rate, oxygen saturation by pulse oximetry (SpO2) were recorded. For post-operative analgesia, subjects received paracetamol 1 gr IV and intermittent epidural analgesia regimen in a 10 cc syringe: Group 1 received Bupivacaine 0,125% 12,5 mg combined with dexamethasone 8 mg plus 0,9% sodium chloride (NaCl) until the volume was 10 cc; Group 2 received Bupivacaine 0,125% 12,5 mg combined with morphine 2 mg plus 0,9% NaCl until the volume was 10 cc. The injection was given by anesthesiology residents without knowing the syringe's content. Patient Controlled Analgesia (PCA) morphine was given in the recovery room. Data recorded were blood pressure, heart rate, respiratory rate, oxygen saturation, visual analog scale, side effects, the time when first additional analgesia was needed by subjects, the opioid requirement within 24 hours post-operation. Data was analyzed using Statistical Package for the Social Sciences (SPSS) software, for numerical data using unpaired T-test or Mann-Whitney-U test, for categorical data using Chi-square or Fisher Exact Test. Data normality was tested by Kolmogorov-Smirnov test. Significant value is p<0.05.

Inclusion criteria

• Subjects aged 18-60 years old with American Society of Anesthesiologists (ASA) physical status I-II and body mass index (BMI) 18,5-25 kg/m2 who were planned to undergo lower extremity surgery
• Subjects have been explained about the study, have agreed to enroll and have signed the informed consent form

Exclusion criteria

• Subjects with history of bupivacaine allergy
• Subjects with history of morphine allergy
• Subjects with history of urine retention
• Subjects with history of gait disturbance or using prosthetic, Subjects with history of peptic ulcer
• Subjects with history of long term use of corticosteroid
• Subjects with contraindications for epidural anesthesia
• Subjects rejected to participate in the study.

Drop out criteria:

• Subjects with epidural anesthesia complications (e.g. shock, anaphylactic reaction, seizures, severe respiratory disturbance)
• Subjects with failed epidural anesthesia.