Adding magnesium to levobupivacaine for axillary brachial plexus block in arteriovenous fistule surgery.

Objective: The aim of this study was to compare the effect of adding magnesium to levobupivacaine on sensory and motor block onset and duration for axillary brachial plexus block in chronic renal failure (CRF) patients scheduled for arteriovenous fistule surgery (AVFS).

Methods: 80 patients, ASA III, aged 30 to 70 years, randomized and divided into 4 groups: Group I (n = 20) received total 41 ml of levobupivacaine 0.5 % + 1 ml NaCl 0.9 % mixture; Group II (n = 20) received 41 ml of levobupivacaine 0.5 % + 1 ml magnesium sulfate (150 mg) mixture; Group III (n = 20) received total 41 ml of levobupivacaine 0.25 % + 1 ml NaCl 0.9 % mixture; and Group IV (n = 20) received total 41 ml of levobupivacaine 0.25 % + 1 ml magnesium sulfate (150 mg) mixture by perineural axillary brachial plexus block. All patients were evaluated with regard to motor and sensory blocks. Motor and sensory block ending times were recorded.

Results: Motor and sensory block onset times were statistically decreased in Group II when compared with Goup I, and also the motor and sensory block durations were increased in Group II when compared with Goup I (p < 0.05). Sensory block onset times were statistically decreased in Group IV when compared with Goup III (p < 0.05).

Conclusions: We conclude that by its decreasing effect on local anesthetic dose, magnesium may reduce the side effects due to high local anesthetic doses in patients with CRF (Tab. 1, Ref. 11).