Abstract
The persistent fetal circulation syndrome is associated with significant mortality, despite the availability of pharmacologic agents that dilate pulmonary vasculature. Presently, the most commonly used agent is tolazoline (TLZ). Our 5 yr experience with TLZ includes 39 neonates treated for refractory hypoxemia, defined as PaO2 <50 torr in an FiO2=1.0 with mechanical ventilatory support. Infants received 1-2 mg/kg by bolus, followed by 2-6 mg/kg/hr continuous infusion. A positive response was a sustained increase in PaO2 >20 torr lasting 120 min: 41% of patients responded. The mean increase of PaO2 in responders was 96.3 torr ±17 SEM (p<0.01) vs the non-responders' mean increase of 5.9 torr ±1.8 SEM (p<0.01). Tachyphylaxis occurred in 6 patients (15%). These infants required a gradual increase in dose to 5-6 mg/kg/hr to sustain a response. At this dose no further response was seen; 50% of patients with tachyphylaxis died. Review of other complications revealed: 41% had increased gastric secretions; 28.2% became hypotensive; 23% had gastric bleeding; 12.8% developed thrombocytopenia (<100,000); 7.7% developed tachycardia (>180/min); 5% had decreased urine output (<1 cc/kg/hr); 2.6% had pulmonary hemorrhage. Conclusions: 1) <50% of patients responded and response appeared to ba an all or none phenomenon, 2) response is associated with improved survival, and 3) despite initial response, TLZ tachyphylaxis occurred in some infants with an associated decrease in survival.
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Slack, M., Desai, N., Cunningham, M. et al. 1430 TOLAZOLINE: LIMITED EFFICACY IN PULMONARY VASO-REACTIVE HYPOXEMIA. Pediatr Res 15 (Suppl 4), 681 (1981). https://doi.org/10.1203/00006450-198104001-01459
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DOI: https://doi.org/10.1203/00006450-198104001-01459