Efficacy and safety of tolazoline for treatment of severe hypoxemia in extremely preterm infants.

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To determine the efficacy of tolazoline as a rescue treatment for hypoxemia in preterm infants with respiratory distress syndrome. Retrospective chart review on case series of infants weighing < 750 g at birth who received tolazoline during a severe hypoxemic episode while receiving maximal ventilator support for respiratory distress syndrome. A slow bolus infusion of low dose tolazoline (0.5 mg-2 mg/kg) mixed with plasmanate or normal saline (10 mL/kg) was administered. Outcome measures evaluated included an increase in PaO(2) > or =20 mm Hg from pretreatment value and an increase in oxygen saturation to > or =90%. Forty-three infants with a mean gestational age and birth weight of 24 weeks and 581 g, respectively, received tolazoline. All infants were mechanically ventilated and required a fraction of inspired oxygen of 1.0. Oxygenation improved in 72% (31/43) of infants with a tolazoline dose of 0.5 to 1.0 mg/kg. Of those who responded, PaO(2) values (mean +/- standard deviation) pretolazoline and posttolazoline were 32 +/- 7.5 mm Hg and 156 +/- 114.9 mm Hg, respectively. In all responders, oxygen saturation increased to > or =90% within 30 minutes of tolazoline administration. Improvement in pH, pCO(2), oxygenation index, and mean airway pressure was also noted. Among nonresponders, pH decreased and pCO(2) increased after tolazoline. Minimal change in blood pressure was noted in both responders and nonresponders. Heart rate decreased by 19 beats per minute among nonresponders compared with an increase of 3 beats per minute in those who responded to tolazoline. Tolazoline is an effective treatment of severe resistant hypoxemia in preterm infants who are already on vigorous ventilatory support.