Postoperative analgesia by femoral nerve block with ropivacaine 0.2% after major knee surgery: continuous versus patient-controlled techniques

Abstract

Background and objectives: This prospective study compared the efficacy and adverse effects after knee surgery of ropivacaine 0.2% administered as patient-controlled femoral analgesia (PCFA), as a continuous femoral infusion (Inf), or as both (PCFA+Inf).

Methods: Before general anesthesia, 140 adults scheduled to undergo major knee surgery received a sciatic/fascia iliaca nerve block with 0.75% ropivacaine (40 mL). After surgery, they were randomly assigned to receive, through the femoral catheter, an infusion of 0.2% ropivacaine administered as PCFA (boluses of 10 mL with a lockout time of 60 minutes), Inf (10 mL/h), or PCFA + Inf (5 mL/h plus boluses of 5 mL with a lockout time of 60 minutes). Pain was assessed at rest, on mobilization, and during physiotherapy using a visual analog scale (VAS). Additional use of intravenous (IV) analgesics was noted.

Results: Patients in all 3 groups experienced similar pain relief at rest, on mobilization, and after physiotherapy (P >.05). Additional use of analgesics and overall patient satisfaction (excellent or good in 80% of cases) were also similar in all groups. However, total postoperative ropivacaine consumption was lower in the PCFA group, 150 mL/48 h (90.5 to 210); than in the Inf group, 480 mL/48 h (478 to 480); and the PCFA + Inf group, 310 mL/48 h (280 to 340) (P <.05). Adverse events were similar in all 3 groups (hypotension, vomiting, insomnia). No paresthesia or motor block were observed.

Conclusion: All 3 strategies provided effective pain relief. PCFA resulted in a lower consumption of ropivacaine (toxic and financial impact). PCFA + Inf does not improve postoperative analgesia.