Evaluation of the analgesic effects of lidocaine, bupivacaine and bupivacaine+lidocaine mixture used for ultrasound-guided femoral nerve block on total knee arthroplasty

The aim of this study is to investigate the effects of ultrasonography (US) guided femoral nerve block with lidocaine, bupivacaine and mixture of bupivacaine +lidocaine for the early postoperative pain treatment in the patients undergoing total knee arthroplasty (TDA) under general anesthesia. Sixty-six ASA physical status I–III patients, aged 40-80 years, undergoing unilateral total knee arthroplasty were enrolled in this clinical study. Patients were randomly assigned into 3 groups (each group 22 patients); Group B (Bupivacaine Group), Group L (Lidocaine Group) and Group B + L (Bupivacaine + Lidocaine Group). After the monitoring, the induction of anaesthesia was achieved with Propofol 2 mg/kg, 1 mcg/kg Fentanyl and 0.6 mg/kg Rocuronium was used for muscle relaxation. After endotracheal intubation, the patients were mechanically ventilated to maintain their end-tidal CO2 values between 34 and 38 mmHg. In 3 lt/min fresh gas flow with mixture of %50 N2O/O2 and % 1.5-2.0 Sevoflurane was used for maintenance of anesthesia. US guided femoral nerve block performed with 15 mL of 0.5% Bupivacaine HCI to Group B, 15 mL 2% Lidocaine HCI to Group L and 7.5 mL of 0.5% Bupivacaine HCI and 7.5 mL of 2% Lidocaine HCI to Group B + L under general anesthesia. After the femoral nerve block, the patients were extubated. All the patients admitted to the postanaesthesia care unit, were followed for at least 1 h until complete recovery. After arrival in the postanesthesia care unit, the patients were connected to a PCA device and administered with tramadol HCl (50 mg bolus dose, 20 min lockout time) via this device. Pain scores, tramadol consumption and side effects were recorded by one of the authors blinded to the patient group. Pethidine HCl was administered 0.5 mg/kg intravenously as a rescue analgesia if the VAS value was >5. There were no statistically significant differences between the groups in terms of their age, sex, demographics, and clinical characteristics (P > 0.05 for all). The median VAS scores of rest and action at the 8th and the 12th hour was significantly lower in Group B than in Group L and Group B+L (P< 0.001 for both). It was found that tramadol consumption in Group B was statistically significant lower than Group L and Group B+L Group C within the postoperative 0-12 h, 12-24 h and 0–24 h period (P < 0.05 for all). Group B showed statistically significant higher patient satisfaction compared to Group L and Group B+L (p < 0.05). Based on this study, US guided single shot femoral nerve block provides effective analgesia in early postoperative period, reduces opioid consumption and increase the patient satisfaction. Also single shot femoral block with bupivacaine is much more effective than lidocaine and bupivacaine + lidocaine.