Behavior-state-dependent changes in human fetal pulmonary blood flow velocity waveforms

Abstract

Objective: To establish the influence of fetal behavior stateson venous and arterial pulmonary blood flow velocity waveformsin the normally developing term fetus.Methods: The relation between venous and arterial pulmonaryblood flow velocity waveforms and fetal behaviorstates was investigated in 18 normal term fetuses. Recordingsof the venous pulmonary blood flow velocity waveformswere obtained just proximal to the entrance in the leftatrium, and the arterial pulmonary blood flow velocitywaveforms were taken from the most proximal branch of thepulmonary artery in the same lung using color Dopplerimaging. Time-averaged peak systolic, peak diastolic, andend-diastolic flow velocity; peak systolic to peak diastolicratio; pulsatility index; and fetal heart rate were calculatedfrom both venous and arterial Doppler recordings obtainedduring behavior states 1F (quiet sleep) and 2F (active sleep).Fetal behavior states were determined from combined recordingsof fetal eye and body movements.Results: Recordings of sufficient quality for analysis wereobtained from ten fetuses. Venous pulmonary blood flowvelocity waveforms demonstrated a statistically significantincrease in time-averaged peak diastolic and end-diastolicvelocity during fetal behavior state 2F. No behavior-staterelatedchanges were observed for the arterial pulmonaryblood flow velocity waveform.Conclusion: The data suggest an increased pressure gradientbetween the pulmonary venous system and the leftatrium during behavior state 2F. Flow velocity waveformsfrom the proximal arterial pulmonary branch are independentof behavioral state