Plasma levels of levobupivacaine during continuous infusion via a wound catheter after major surgery in newborn infants

Background Epidurals may be challenging in neonatal patients due to technical difficulties relating to insertion and the risk of local anaesthesia toxicity. The use of wound catheters with an infusion of local anaesthetic has been shown to be well tolerated in adults and older children. There are few data concerning wound catheter techniques in neonatal patients. Objectives The primary aim of this study was to analyse plasma levels of levobupivacaine associated with continuous wound infiltration via a catheter following neonatal surgical procedures. Secondary parameters, including the quality of postoperative analgesia and wound healing, were also noted. Design A prospective, observational study. Setting Paediatric ICU at the Karolinska University Hospital, Stockholm, Sweden, from March 2008 to December 2010. Patients Twenty newborn infants (median weight 3.48 kg) scheduled for major abdominal or thoracic surgery were included. Exclusion criteria were known or suspected hepatic dysfunction. Before skin closure, a subcutaneous catheter was inserted into the wound followed by a 0.5 mg kg(-1) bolus of levobupivacaine (0.125%, 0.4 ml kg(-1)) through the catheter. A continuous infusion was started 20 to 30 min later at a rate of 0.2 mg kg(-1)h(-1) (0.16 ml kg(-1) h(-1)). Main outcome measures Plasma concentrations of levobupivacaine (total and unbound) at 12, 24, 48 and 72 h postoperatively. Morphine consumption, pain scores and wound healing were also analysed. Results Median concentrations of unbound and total levobupivacaine at 72 h were 0.018 and 1.305 μg ml(-1), respectively. In 18 out of 20 infants [90%; 95% confidence interval (CI) 68.3 to 98.8], the unbound plasma concentration of levobupivacaine remained relatively stable and below 0.05 μg ml(-1) throughout the 72 h observation period. Pain scores and morphine consumption levels were low. All wounds except one healed within 10 days. Conclusion The studied infusion regimen was associated with plasma levels of levobupivacaine well below those associated with toxicity. Adequate wound healing, low pain scores and a reduced need for opioids were also noted.