Serum lidocaine and bupivacaine levels in local technique knee arthroscopy

We investigated serum levels of lidocaine and bupivacaine following their intraarticular and subcutaneous injection for anesthetic effect in local technique knee arthroscopy. Fifteen patients scheduled for knee arthroscopy, but who were otherwise healthy, were studied. Following preparation of the knee, 25 cc of 1% lidocaine with epinephrine (1:100,000) and 25 cc of 0.25% bupivacaine were instilled into the knee joint. An additional 40 cc of the combined solution was used to anesthetize four arthroscopic portal sites from the skin into the joint capsule. The arthroscopic procedure was then performed. We took blood samples 5, 15, 30, 60, and 120 minutes after intraarticular injection. High-performance liquid chromatography was used to determine serum values of the agents. Levels of the anesthetic agents in all of the patients at all time intervals were well within the ranges considered safe. Patient surveys of these and 49 other patients indicated a high degree of satisfaction with the technique. No complications from the anesthetic agents were noted at our hospital in over 500 similar cases. We conclude that local anesthesia as described here is a safe and effective alternative to conventional anesthetic techniques. Additionally, it can save time in the operating room and reduce patient costs.