Endotracheal administration of tolazoline in hypoxia-induced pulmonary hypertension.
OBJECTIVE
To compare the pulmonary and systemic vascular responses to intravenously (IV) and endotracheally (ET) administered tolazoline (Tz) in newborn lambs with hypoxia-induced pulmonary hypertension.


METHODS
Randomized, controlled study design.


METHODS
Twenty lambs, 2 to 7 days of age, were anesthetized, intubated, and surgically catheterized for continuous physiologic monitoring and cardiac output measurements using radiolabeled microspheres. After a postoperative stabilization period, the lambs were ventilated with a hypoxic gas mixture which was titrated to increase mean pulmonary artery pressure (MPAP) 30% to 50% above baseline. Each animal was randomly assigned to receive either IV-Tz (2 mg/kg), ET-Tz (4 mg/kg), or ET-saline (Sal, control group).


RESULTS
ET-Tz significantly (P < .05) reduced MPAP, PVRI (pulmonary vascular resistance index), MPAP/mean artery pressure (MAP) and PVRI/systemic vascular resistance index (SVRI), but not SVRI. IV-Tz lowered (P < .05) MPAP, PVRI, and PVRI/SVRI but also produced significant reductions in MAP and SVRI while only transiently decreasing MPAP/MAP: MPAP/MAP and PVRI/SVRI ratios were consistently lower in the ET-Tz animals than either the IV-Tz or ET-Sal animals.


CONCLUSIONS
Our results suggest that ET-Tz produced a more selective pulmonary vascular response than IV-Tz and may warrant further investigation for potential clinical applications.
Curtis
J
J
Department of Pediatrics, Uniformed Services University of the Health Sciences, Bethesda, MD.
O'Neill
J T
JT
Pettett
G
G
D000818:Animals; D000831:Animals, Newborn; D002302:Cardiac Output / Q000187:drug effects; D006801:Humans; D007231:Infant, Newborn; D007262:Infusions, Intravenous; D007442:Intubation, Intratracheal; D010547:Persistent Fetal Circulation Syndrome / Q000188:drug therapy* / Q000209:etiology; D011651:Pulmonary Artery / Q000502:physiology; D011897:Random Allocation; D012756:Sheep; D013997:Time Factors; D014043:Tolazoline / Q000008:administration & dosage* / Q000627:therapeutic use; D014655:Vascular Resistance / Q000187:drug effects
D014043:Tolazoline