POTENTIAL ROUTE FOR FETAL THERAPY - INTRAMEMBRANOUS ABSORPTION OF INTRAAMNIOTICALLY INJECTED FUROSEMIDE

OBJECTIVE: Our purpose was to determine whether intraamniotically inje cted furosemide could be absorbed directly into fetal circulation by t he ovine intramembranous pathway. STUDY DESIGN: Nine chronically cathe terized fetal sheep, five with an intact and four with a surgically li gated esophagus, were studied for 7 hours on 2 consecutive days. Day 1 was a control day in which the fetal parameters of arterial, venous, and amniotic fluid pressures; heart rate; and urine flow were measured continuously. Fetal and maternal blood, amniotic fluid, and fetal uri ne were sampled for osmolality, electrolytes, blood gases, and pH twic e during the first hour and hourly thereafter. On day 2, 15 mg of furo semide was injected into the amniotic cavity after 1 hour and fetuses were monitored in the same fashion as on the control day. RESULTS: On day 2, both intact and ligated fetuses demonstrated a rapid and prolon ged increase in urine flow (p < 0.01) compared with control day fetuse s. Esophageal ligation decreased, but did not eliminate, the diuresis. Free water clearance increased equally (p < 0.05) in both groups comp ared with control fetuses. Sodium and chloride excretion increased sig nificantly in intact (sodium 591% +/- 220% and chloride 763% +/- 295%) and ligated fetuses (sodium 234% +/- 70% and chloride 409% +/- 74%) c ompared with control fetuses. CONCLUSIONS: Diuresis after esophageal l igation demonstrates that furosemide is absorbed by the ovine intramem branous pathway.