Alpha-1-acid glycoprotein and its potential impact on local anesthetic dose in neonates.

ABSTRACT

BACKGROUND: Alpha-1-acid glycoprotein is an acute-phase protein with a high affinity for amide local anesthetics. Compared to adults, neonates have lower concentrations of this glycoprotein in plasma, and are therefore at higher risk of developing local anesthetic toxicity. Alpha-1-acid glycoprotein concentrations rise in adults after surgery as a response to stress as well as in inflammatory conditions. Previous studies have shown that concentrations of alpha-1-acid-glycoprotein in neonates vary postpartum, influenced by gestational age and mode of delivery. AIM: This study aims to determine the concentrations of alpha-1-acid glycoprotein pre- and postoperatively in neonates undergoing major surgery. This information is important for determining safe and effective dosage of local anesthetic in this vulnerable group of patients. METHODS: In this prospective observational study, 25 neonates (median 3 days of age) undergoing major surgery were included. Blood sampling was performed preoperatively and at four occasions postoperatively. Alpha-1-acid-glycoprotein plasma concentrations were analyzed using an immunoturbidimetric assay. Mann-Whitney U test, Kruskal-Wallis and Spearman ranking correlation test were used for the statistical analysis. RESULTS: Higher plasma concentrations of alpha-1-acid-glycoprotein were found 48 h postoperatively compared to preoperatively [median (inter-quartile range) 0.815 g L-1 (0.663-0.983 g L-1 ) vs. 0.300 g L-1 (0.205-0.480 g L-1 p < 0.001)], respectively. It was not possible to detect any influence of sex, postnatal age, gestational age, or delivery mode on alpha-1-acid-glycoprotein concentrations in our data. CONCLUSIONS: Alpha-1-acid-glycoprotein concentrations increase in neonates as a response to surgery regardless of gestational age, sex, or mode of delivery.