Ultrasonic measurement of rate and depth of human fetal breathing: Effect of glucose

Abstract

A recently developed ultrasonic tracking device was used to determine the effect of maternal intravenous glucose infusion on amplitude and frequency of breathing movements in six healthy human fetuses at 38 to 40 weeks' gestation. Following a 2-hour observation period, an intravenous injection of either 25 gm of a 50% glucose solution or an equal volume of saline was given to the mother. Observations were continued for a further 4 hours. Fetal rib cage and abdominal diameters were measured continuously with the ultrasonic tracking device and the information was recorded on a strip chart recorder for later analysis. Breath interval and incidence measurements were highly correlated with data obtained by an independent technique (r ≥ 0.90). During the first 80 minutes after glucose injection, total fetal trunk movement recorded during breathing movements increased from 1.5 ± 0.2 to 2.9 ± 0.4 mm (P < 0.05). There was no significant change in the frequency or variability of fetal breathing movements after glucose infusion.