Fetal breathing and adaptation to maternal hemorrhage in the sheep P.




















M.D. M.D.


The effect of maternal hemorrhage in chronic preparations was studied on fital lambs in the last month of gestation. Fourteen to 20 per cent of maternal blood wasestimated to ha-c~ been remoiled within 30 minutes, which resulted in a drop of 30 per cent of mean matc~mal arterial pressure. A fetal bradycardia started 28 k 13 minutes after the beginning oj maternal hemorrhage. It lasted 30 2 15 minutes and was concomitant with a rise in fetal arterial pressure. It u1a.s followed by a long-lasting fetal tachycardia of 130 + 38 minutes and was corrected only by reinfusion of blood to the mother. The fetal blood gases demon.rtrated a mild asphyxia with a persistent metabolic acidemia until reinfusion of blood to the mother. Maternal and fetal plasma cortisol levels rose significantly at the end of the hemorrhage. Trachealjuidjow did not change. Fetal breathing recorded 20 hours before and 24 hours after the experiment did not shorn consistent changes, but during fetal bradycardia there was no fetal breath,ing. Recent clinical investigations in thisjield have been made in the human fetus to estimate standards of.fetal well being. These peculiar animat experiments do not show any significant improvement by recording fetal breathing over the recording oj‘ prelabor fetal heart rate. (AM. J. OBSTET. GYNECOL. 127: 505, 1977.)

RESPIRATORY movements in the normal fetus were generally thought to be absent until the demonstration was made by our laboratory’, ’ and by Dawes and coworker?, ’ of intrauterine breathing movements in healthy fetal lambs. Fetal breathing was subsequently described in the rabbit,’ in the human species by Boddy and Robinson,’ and in the rhesus monkey by Martin From the Laboratoire du CNRS. H+tal Broussais and Department of Obstetrics and Department of Neonatalogy, Mater&e de Port Royal, Universiti Reni Descartes. Supported bv grant ATP 7.7-1.28 No. I7 and ATP 23.75.46,from the Institut National de la Sante et de la Recherrhr Medicale. Recrirwd

for publicntion

Accepted October


9, 1976.

5, 1976.

Reprint quests: C. Tchobroutsky, Royal, CHU Cochin-Port Roval, Roval, Paris 14e, France.

Materniti de Port 123, boulevard de Port

and associates.6 There were no differences in pH and respiratory gas tensions of fetal arterial blood between breathing and nonbreathing periods.lm3 However. hypoxemia induced by giving the pregnant ewe lowoxygen gas tensions mixture to breathe for 1 hour reduced the incidence of breathing during hypoxia and during the next 6 hours.7 It is now generally admitted that the presence of fetal breathing is a symptom of fetal well being. ‘, ” Using the technique of the in met-o fetal lamb chronic preparation, we studied the changes induced by acute maternal hemorrhage on the fetal breathing movements, heart rate, blood pressure, and biologic variables as blood gases and plasma cortisol. Materials

and methods

Sixteen observations were made on 10 Prealpes fetal lambs of 116 to 13 1 days of gestation. After 24 hours of fasting, the pregnant ewes were anesthetized with in-



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: Heort : Blood : Intro : Intro

rote pressure thorocic amniotic





pressure pressure

Fig. 1. Timing of the experiment travenous injection of 200 mg. of Ketamine.* Anesthesia was maintained with a perfusion of 1 Gm. of ketamine which had been dissolved in 500 ml. of 5 per cent dextrose. The abdominal wall was opened by a midline incision, the ewe lying supine. Catheters were implanted into a fetal carotid artery, the fetal trachea, and the amniotic fluid by a midline incision of the fetal neck without exteriorization of the fetal head. An electrode was inserted beneath the fetal skin to record instantaneous fetal heart rate.? The catheters were brought out through the maternal flank. A catheter was inserted into the carotid artery of the ewe. In order to collect tracheal fluid in five ewes. the fetal trachea was ligated around the largest fitting cannula inserted 2 cm. toward the lower part of the trachea. The cannula was connected to the input of a micropack plastic bag (volume 250 ml.) which remained inside the amniotic cavity. The output of the bag was inserted into a catheter which was also brought out through the flank of the mother with the other catheters. A third catheter positioned in the thoracic segment of the trachea passed through the whole system in order to measure the tracheal pressure. The ewes were allowed to recover for at least 3 days after surgery before any experiment was performed. Thereafter, an interval of at least 3 days was left before *Ketalar, Parke-Davis. WZardiotachymeter Roche 540.

any further experiments. A continuous rrcord of fetal instantaneous heart rate and of arterial, tracheal, and amniotic pressure was made 20 hours before, during, and 24 hours after the experiment. Maternal arterial pressure was recorded only during the 3% hours of the experiment. Pressures were measured with Statham P.23 pressure transducers connected to a Brush Mark 260 recorder. After the control period a maternal hemorrhage of 800 ml. was induced within 30 minutes. The weight of the ewes was hetlceen 45 and 65 kilograms. and the percentage of blood removal was estimated to be between 14 and 20 per cent of total blood volume.Y The animal was allowed to remain at this level of bleeding for 90 minutes. A reinfusion was carried out during which the blood was reinfused to the mother at the same rate at which it was removed. Maternal and fetal arterial blood samples were collected anaerobically in syringes in which the dead space was filled with heparin. Blood Po2, Pco2, and pH were immediately measured at 37”

Fetal breathing and adaptation to maternal hemorrhage in the sheep.

Fetal breathing and adaptation to maternal hemorrhage in the sheep P. L. M. TOUBAS, M.D. MONSET-COUCHARD, P. REY, J. PREDINE, M. M.D. PH.D...
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