Interscalene brachial plexus block with bupivacaine and ropivacaine in patients with chronic renal failure: Diaphragmatic excursion and pulmonary function changes

Abstract

In this randomized, double-blind study, we compared the anesthetic characteristics and pulmonary function changes of 0.33% bupivacaine and 0.33% ropivacaine used for interscalene brachial plexus (IBP) anesthesia in patients with chronic renal failure. Forty-two patients undergoing IBP anesthesia for creation of arteriovenous fistulas were randomly allocated to receive either 30 mL of 0.33% bupivacaine (Group B) or 0.33% ropivacaine (Group R). Block onset time, diaphragmatic excursion (ultrasonographic evaluation), and free plasma concentrations of bupivacaine and ropivacaine were evaluated. Negative motion or immobility of the ipsilateral hemidiaphragm and a decrease of > 10 mm in positive motion were defined as diaphragmatic paresis. The pulmonary function variables were measured by bedside spirometry equipment. Seven patients needed supplemental local anesthetic, one with total spinal block; these patients were excluded from the study. The success rate was 80.9%. Block quality was similar in the two groups. Ipsilateral hemidiaphragmatic excursion was decreased in both groups compared with baseline values (P 0.05). Pulmonary function significantly decreased from baseline in both groups (forced vital capacity (FVC) 30%, forced expiratory volume at 1 second (FEV1) 32%, and peak expiratory flow (PEF) 31% in Group B and FVC 17%, FEV1 17%, and PEF 5% in Group R) (P 0.05). Concentrations of bupivacaine and ropivacaine were below toxic levels rather than "normal range." We conclude that pulmonary function decreased more after IBP with 0.33% bupivacaine than with 0.33% ropivacaine.