Subcutaneous infusion anesthesia with diluted mixtures of prilocain and ropivacain

Local anesthesia often suffices for surgery on the outside of the body. In recent years, it has been found that such local anesthesia can be adequately carried out using large amounts of highly diluted anesthetic solutions.

Using one or more common infusomats, we injected mixed anesthetic solutions slowly, painlessly, paravenously, and automatically via subcutaneous infusion anesthesia (SIA) into the subcutaneous layer in a large group of patients scheduled for surgery. The local anesthetics used were prilocaine and ropivacaine (Xylonest and Naropin); these were diluted with original Ringer's solution with epinephrine (1: 1,000,000) in 500-ml bottles. The concentration of the mixture varied between 0.3% and 0.08% depending on the requirements of surgery. The needles used ranged from 30-gauge to 20-gauge needles, with a length of 1.5-10 cm. The speed of injection varied between 30 ml/h and 1500 ml/h, depending on the location, the requirements of the surgery and the needle size. Volumes usually ranged from 2 ml to 600 ml depending on the concentrations used. The maximum dose was approximately 4 mg/kg prilocaine and 2 mg/kg ropivacaine.

We used this technique in preparing for 5020 major and minor skin operations in 3270 patients ranging in age from 0.5 years to 95 years (mean age 54 years). Microbiological tests of the infusion system were carried out. Patients were asked about their pain during anesthesia, operation, and postoperatively.

There were no complications from local anesthesia. The technique proved safe and comfortable even for children and very sensitive patients. The median duration of postoperative anesthesia was 5 h (maximum 23 h). Choosing the concentration, the needle, the needle position, the flow rate, and the volume requires some experience.