Affiliation:
1. Anesthesiology Department, The Second Hospital of Dalian Medical University, Dalian, Liaoning, China
Abstract
Continuous nerve block of unilateral paravertebral canal is one of the most reliable and the most commonly performed techniques to control intra- and postoperative pain. It is the technique of injecting local anaesthetic alongside the thoracic vertebra close to where the spinal nerves emerge from the intervertebral foramen. This produces unilateral, segmental, somatic, and sympathetic nerve blockade, which is effective for anaesthesia and in treating acute and chronic pain of unilateral origin from the chest and abdomen. Ultrasound guidance with or without nerve stimulator has reduced the amount of local anaesthetics (LA) to achieve a successful block, which may minimize complications of continuous nerve block of unilateral paravertebral canal. Previous studies have suggested that continuous nerve block of unilateral paravertebral canal with ropivacaine combined with small doses of triamcinolone was effective to achieve sensory and motor block after lung cancer surgery. Previous studies have used a fixed large dose in different volumes and concentrations for a nerve block, infraclavicular block, axillary block, and humeral canal block. The results of these studies with the respects of onset time, successful rate, and block duration were not consistent. Various factors, including the technique used, the anatomic aspects of the injection, and the pharmacodynamics aspect of drug, may influence the results. We tested the hypothesis that 50,25,10 mg ropivacaine and 50,25,10 mg triamcinolone of three combinations of volumes and concentrations for ultrasound-guided continuous nerve block of unilateral paravertebral canal produce different effects in the aspect of survival rate. Here, the drug effect was analyzed using the cross cluster K-nearest neighbors (KNN). The whole experimentation was carried out under MATLAB environment.