Objective: To establish the influence of fetal behavior states<br/>on venous and arterial pulmonary blood flow velocity waveforms<br/>in the normally developing term fetus.<br/>Methods: The relation between venous and arterial pulmonary<br/>blood flow velocity waveforms and fetal behavior<br/>states was investigated in 18 normal term fetuses. Recordings<br/>of the venous pulmonary blood flow velocity waveforms<br/>were obtained just proximal to the entrance in the left<br/>atrium, and the arterial pulmonary blood flow velocity<br/>waveforms were taken from the most proximal branch of the<br/>pulmonary artery in the same lung using color Doppler<br/>imaging. Time-averaged peak systolic, peak diastolic, and<br/>end-diastolic flow velocity; peak systolic to peak diastolic<br/>ratio; pulsatility index; and fetal heart rate were calculated<br/>from both venous and arterial Doppler recordings obtained<br/>during behavior states 1F (quiet sleep) and 2F (active sleep).<br/>Fetal behavior states were determined from combined recordings<br/>of fetal eye and body movements.<br/>Results: Recordings of sufficient quality for analysis were<br/>obtained from ten fetuses. Venous pulmonary blood flow<br/>velocity waveforms demonstrated a statistically significant<br/>increase in time-averaged peak diastolic and end-diastolic<br/>velocity during fetal behavior state 2F. No behavior-staterelated<br/>changes were observed for the arterial pulmonary<br/>blood flow velocity waveform.<br/>Conclusion: The data suggest an increased pressure gradient<br/>between the pulmonary venous system and the left<br/>atrium during behavior state 2F. Flow velocity waveforms<br/>from the proximal arterial pulmonary branch are independent<br/>of behavioral state
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