Effect of respiratory acidosis on body movements in the chronically instrumented fetal lamb

Background. In respirator) acidosis, it is reported that the fetal breathing movements as well as the fetal heart rate variability increase. As the increase of these two kinds of fetal activities is occasionally observed in normal conditions, it is difficult to distinguish respiratory acidosis and normal conditions by mere observation of these activities. As the third diagnostic variable, if a different feta! body movement response to respiratory acidosis is observed, it would be helpful for better diagnosis in combination with other activities. We investigated the effect of respiratory acidosis on body movements in the chronically instrumented fetal lamb. Methods. A total of four experiments were performed on four ewes. Respiratory acidosis was induced in the fetus by maternal administration of a high carbon dioxide gas mixture for 1 hour. Fetal body movements were observed by real-time ultrasonography. The frequency of body movements was expressed as the number of each movement in a 30-minute period. Re...