The Efficacy of Automated Intermittent Boluses for Continuous Femoral Nerve Block: a Prospective, Randomized Comparison to Continuous Infusions

The Efficacy of Automated Intermittent Boluses for Continuous Femoral Nerve Block: a Prospective, Randomized Comparison to Continuous Infusions

The optimal infusion technique (continuous rate vs. intermittent bolus) for peripheral nerve blocks has not been established. To our knowledge, this is the first study to compare the efficacy of an automated intermittent bolus technique to a continuous rate of infusion of local anesthetic in femoral nerve catheters. We hypothesized that the intermittent bolus technique would provide enhanced analgesia compared to a continuous infusion rate as assessed by intravenous patient-controlled analgesia (IV-PCA) hydromorphone consumption and visual analog scale (VAS) pain scores.

Inclusion Criteria:

• American Society of Anesthesiologists (ASA) physical status 1 through 3
• elective, primary, unilateral TKA

Exclusion Criteria:

• patient refusal
• pregnancy
• diabetic neuropathy or any other neurologic or neuromuscular disease
• rheumatoid arthritis
• current coagulopathy
• skin infection at needle insertion site for the femoral or sciatic blocks
• significant renal or hepatic impairment
• unsuccessful femoral or sciatic block or femoral catheter placement
• femoral catheter dislodgement after placement
• inability to understand VAS pain scales
• inability to use an IV-PCA pump