Clinical correlates do not predict PaO₂ response after tolazoline administration in hypoxic newborns

In an attempt to determine which hypoxic newborns might benefit from administration of tolazoline hydrochloride (Tz), we identified all neonates known to have received Tz at four Chicago area perinatal centers over a 4-yr period. For each of 41 infants, five statistical analyses were used to correlate 31 clinical and ventilatory variables with PaO₂ values before and after Tz administration. Fourteen neonates responded to Tz infusion with more than a two-fold increase in PaO₂. None of 31 clinical variables successfully predicted a positive Tz response in these infants, and a positive response (increased PaO₂) was not associated with increased likelihood of survival. BP fell after Tz in 72% of patients, while heart rate rose after Tz treatment in 66% of cases. These data suggest a need to re-evaluate the administration of Tz to hypoxic newborn infants.