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

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.