Fetal cardiovascular response to hypoxemia is dependent upon gestational age in rhesus monkeys

Abstract

TATIONAL AGE IN RHESUS MONKEYS JORGE TOLOSA, JUHA RASANEN, ELIOT SPINDEL, JOHN FANTON, LEONARDO PEREIRA, PATRICIA ROBERTSON, MICHAEL GRAVETT, Oregon Health & Science University (OHSU), Maternal Fetal Medicine, Portland, Oregon, University of Oulu, Obstetrics and Gynecology, Oulu, Finland, OHSU, Oregon National Primate Research Center (ONPRC), Division of Neuroscience, Beaverton, Oregon, OHSU, ONPRC, Surgery Svs, Beaverton, Oregon, OHSU, ONPRC, Maternal Fetal Medicine, Portland, Oregon OBJECTIVE: To test the hypothesis that cardiovascular responses to hypoxemia change with advancing gestation and demonstrate the value of a unique animal model using non-human primates. STUDY DESIGN: Rhesus macaques with timed gestations underwent Doppler ultrasonographic examination at 91 (n=2) gestational days (term is 165 days), at 104 (n=1) days and at 140 (n=1) days of gestation while sedated with continuous rate infusion ketamine (400-500 mcg/kg/min). Fetal cardiovascular hemodynamics were evaluated (Voluson 730 Expert, GE Healthcare, USA) prior to and during fetal hypoxemia which was induced by decreasing maternal inhaled oxygen content; (gas mixture was approximately 70% oxygen and 30% helium) to achieve a pulse oximetry of 80% saturation. RESULTS: Umbilical artery, right pulmonary artery (RPA), middle cerebral artery pulsatility index (PI) values all decreased with advancing gestation. The ductus venosus and inferior vena cava PI values did not show a similar trend. During hypoxemia, fetal cardiovascular hemodynamic parameters remained unchanged at 91 and 104 gestational days. However, at 140 days fetal hypoxemia led to a 3-fold increase in RPA PI values when compared with baseline. CONCLUSION: Rhesus macaque fetuses demonstrated changes in cardiovascular hemodynamics similar to human fetuses with advancing gestational age. At 140 days of gestation, fetal pulmonary artery vascular impedance increased in response to hypoxemia. (Supported by NIH grants AI42490 and HD/HL37131).