Treatment of persistent fetal circulation syndrome of the newborn. Comparison of different doses of tolazoline

Summary

The effects of two doses of tolazoline have been compared in 2 groups of newborns suffering from the persistent fetal circulation syndrome. The effects on PaO₂ and AaDO₂ were similar in the 2 groups who received either a bolus of 1 or 0.5 mg·kg⁻¹ tolazoline, followed by a continuous infusion of 1 or 0.5 mg·kg⁻¹·h⁻¹. The observed changes did not differ significantly from those previously observed in babies treated with 2 mg·kg⁻¹. A rise in PaO₂ and a reduction in AaDO₂ were usually observed shortly after the bolus injection and at plasma levels between 1.5 and 4 µg·ml·⁻¹. A progressive rise in plasma level over time occurred after 1 mg·kg⁻¹ (and in the previous study of 2 mg) but not with 0.5g/kg tolazoline. The elimination half-life of tolazoline in 6 patients was 5 to 13 h. The data suggest that continuous infusion of tolazoline is not necessarily required and that the dose of 0.5 mg/kg is more appropriate and safer than the higher doses usually proposed.