[Spinal anesthesia for outpatient pediatric surgery in 1 - 5 years old children with 0.5% isobaric enantiomeric mixture of bupivacaine (S75-R25)].

BACKGROUND AND OBJECTIVES Commercially available bupivacaine is a racemic mixture of S(-) and R(+) enantiomers. Although the S(-) bupivacaine enantiomer is less toxic than R(+) bupivacaine to cardiovascular and central nervous systems, its relative efficacy has not yet been determined in spinal anesthesia for pediatric surgery. The aim of this study was to evaluate the effects of spinal anesthesia with a 0.5% isobaric mixture of S(-) bupivacaine(75%) + R(+) bupivacaine(25%) in 40 children aged 1 to 5 years scheduled for outpatient surgery. METHODS Participated in this prospective study 40 patients aged 1 to 5 years submitted to spinal anesthesia with 0.5 mg.kg-1 of a 0.5% isobaric mixture of 75% S(-) bupivacaine + 25% R(+) bupivacaine. The following parameters were observed: onset of analgesia, degree of motor block, duration of effects, cephalad spread of analgesia, cardiovascular changes, incidence of headache and transient neurological symptoms. RESULTS Mean onset time was 2.29 +/- 0.64 min. Duration of analgesia was 4.13 +/- 0.89 h. Time to ambulate was 3.50 +/- 0.81 h. Mean PACU stay was 43.80 +/- 31.34 min. Motor block duration was 1.89 +/- 0.78 h. Sensory block level varied from T9 to T4 (Mode=T6). Motor block onset time was less than two minutes in all children, all reaching grade 3 motor block (modified Bromage scale) in the beginning of surgery. Over 55% of all patients recovered to motor block 1 or zero at the end of the surgery. No patient developed oxygen desaturation or arterial hypotension. Bradycardia was observed in one patient. There were two block failures. There were no headache or transient neurological symptoms. CONCLUSIONS Isobaric 0.5% levobupivacaine (R25-S75) induces a safe spinal anesthesia in patients aged 1 to 5 years scheduled for outpatient procedures, with a high success rate, short-lasting motor block, relatively low incidence of side effects and at a lower cost. Headache seems to be rare in patients below five years of age when a thin needle is used. Our results have shown that spinal anesthesia is a safe and easy technique for children between 1 and 5 years of age in outpatient procedures.