Abstract
Clinical respiratory distress (RD), serial pulmonary blood flow (PBF), and 4 hr lung water in 6 preterm lambs after mechanically closing the DA at age 10 min (Group A) were compared with those in 8 lambs in which the DA was not closed (Group B). During fetal surgery at 128-132 d, an electromagnetic flow probe was placed on the postductal segment of the common pulmonary artery in both groups; a polyethylene snare was placed loosely around the DA in Group A. The lambs were delivered by C-Section 8 days later. PBF rose rapidly in both groups. The snare was tightened at age 10 min to close the DA (Group A) during which little clinical change was noted. PBF in Group A peaked close to the time of DA closure (median=10.6 min), earlier than the PBF peak in Group B (median=25.0 min; p <.05). Peak PBF as well as the PBF at 2 and 3 hr was lower in Group A (p <.05). Clinical RD was similar in both groups. Although lung water tended to be lower in Group A, this was not statistically significant.
Left-to-right DA shunting thus appeared to contribute significantly to the high PBF during and after the initial surge but had minimal or no effect on lung water. These data together with our previous experiments (Ped. Res. 17:124A, 1983) suggest that the high PBF associated with ovine RD is a secondary phenomenon and point to defective pulmonary vascular resistance as the primary cause for the pulmonary edema found in this disease.
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Stinson, D., Allen, A., Roy, D. et al. 1533 EFFECT OF CLOSING THE DUCTUS ARTERIOSUS (DA) AT AGE 10 MIN IN PRETERM LAMBS. Pediatr Res 19, 366 (1985). https://doi.org/10.1203/00006450-198504000-01557
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DOI: https://doi.org/10.1203/00006450-198504000-01557