John Lind

DISTRIBUTION OF BLOOD BETWEEN INFANT AND PLACENTA AFTER BIRTH

Abstract The distribution of the circulatingblood volume in the infant-placental circuit at birth and in the first minutes after birth was studied in 111 normal full-term deliveries. The blood-volume of the infants, divided in groups where umbilical cords were clamped at various times, was measured by the 125 I-serum-albumin dilution method, and the placental residual blood-volume was measured by drainage both when the placenta was still in utero and after its delivery. The distribution of the blood between the infants and placental circuits was about 67%/33% at birth, 80%/20% at 1 minute, and 87%/13% at the termination of placental transfusion.

EFFECT OF GRAVITY ON PLACENTAL TRANSFUSION

Abstract The effect of gravity on placental transfusion was studied by measuring the placental residual blood volume (P.R.B.V.) in one hundred and twelve normal deliveries with the infants kept at different levels above or below the mothers introitus after birth. The results demonstrated that hydrostatic pressure, brought about by keeping the infant 40 cm. below the introitus, hastened placental transfusion to almost completion at about 30 seconds. In the presence of this effect of gravity, prolonging the time of cord clamping to 3 minutes did not result in a significantly larger amount of placental transfusion. Whereas, the effect of hydrostatic pressure created by having the infants held above the level of the mothers introitus lessened or prevented placental transfusion by partially or completely obliterating the pressure generated by uterine contraction.

PLACENTAL TRANSFUSION-RATE AND UTERINE CONTRACTION

Abstract Blood-volume was determined in three hundred and one healthy full-term infants after their cords were clamped at different time-intervals after birth. The infants were divided into two groups, depending on whether the mothers received intravenous methylergometrine during the early third stage of labour or not. The results demonstrated that postnatal transfer of the placental blood to the baby took place at a rapid rate and in a stepwise manner, amounting to about 55% of the babys blood-volume at birth. This stepwise and rapid rate of placental transfusion correlated with the time of uterine contraction during the third stage of labour. In relation to the uterine contraction at birth, about 23-30% of the blood was transferred during the first 10 to 15 seconds. The remaining 70-77% of blood transfer in the non-methylergometrine group was effected partly at 1 minute and completely at 3 minutes after a uterine contraction, whereas in the methylergometrine group, placental transfusion was accelerated, and the remaining 70-77% of blood was almost completely transferred at 1 minute owing to an earlier and enhanced uterine contraction which, it is suggested, plays a key part. No direct significant influence of respiration on placental transfusion was demonstrated.

CHANGES IN THE LIVER CIRCULATION AT BIRTH.

In 1628 William Harvey1 introduced his concept of the circulation of the blood and included in his treatise the first account of the fetal circulation. Concerning the liver circulation Harvey wrote, “In the embryo the liver has practically no function-the umbilical vein passes intact through the viscus and from the porta hepatis there is an opening so that blood returning from the intestine makes for the heart not through the liver but by the aforesaid umbilical vein.” In the centuries following Harvey, the course of the fetal circulation was a subject for speculation and controversy among anatomists. In 1736 Trew2 gave a correct description of the essential relationship between the extraand intrahepatic circulation; and 16 years later Bertin3 demonstrated that the left lobe of the liver is supplied mainly from the umbilical vein, while the right lobe receives blood froin branches common to both the umbilical and portal veins. A complete anatomical description of the fetal circulation was given by Ziegenspeck4 in 1910. The solution of the gross physiological problems of fetal circulation came later with the studies by H ~ g g e t , ~ who demonstrated that it was possible to deliver a goat fetus still attached to the mother, with the umbilical cord intact and in reasonably good physiological condition. Blood gas analyses by Dawes and coworkerss and roentgen visualization of intraand extrahepatic blood flow in the living specimen by Barclay and coworkers7 have clarified much of the fetal cardiovascular physiology.

Effect of Posture and Insulin Hypoglycemia on Catecholamine Excretion in the Newborn1

Release of catecholamines from their sites of production can result from a variety of stimuli. With the increasing recognition of differences between the physiological actions of noradrenaline and adrenaline, it is of interest that different forms of stimuli have been found to cause release of noradrenaline and adrenaline in varying proportions. Thus, adrenaline is selectively excreted in the urine in increased amounts following insulin (lo), whereas carotid occlusion produces mainly noradrenaline release into the suprarenal venous blood of cats (15). When adults are placed in an upright position, an increased urinary excretion of both amines occurs, as reported by Euler, Luft & Sundin (11); this increase in release of predominantly noradrenaline is induced by the orthostatic fall of the blood pressure, acting over the baroreceptor homeostatic reflex mechanisms of the carotid sinus and aorta. The increase in noradrenaline excretion during erect posture appears, then, to provide a means of evaluating

A THERMOGRAPHIC STUDY OF INFANTS EXPOSED TO COLD

There is conclusive evidence that brown adipose tissue is the main site of heat production in response to cold exposure in newborn rabbits (5). Human infants possess about 15 g of brown adipose tissue, part of which is situated in the neck and between the scapulae (2). I t has been demonstrated indirectly that brown adipose tissue in newborn babies is also influenced by cold. Heim et al. for instance found at postmortem examination a depletion of the lipid in brown fat cells of infants exposed to low ambient temperature during life (10). Brown fat is richly vascularized and during cold exposure as well as during nor-epinephrine infusion the blood flow through the tissue is greatly increased (9), thus dispersing the heat. Heat, released by cold-induced metabolism of the cervical and interscapular brown adipose tissue, is transferred via direct venous connections to the vertebral sinus (14). In guinea pigs, a thermosensitive area in the cervical spinal cord has been found and outlined. The warmed blood drained from the brown adipose tissue might protect vital nerve centres during cold exposure. In these animals shiver-

≫Pre‐excitation≫ of the ventricular part of the heart and its occurrence in children.

The author gives a brief description of the term pre‐excitation, one of the points emphasized being the great morphological diversity shown by the electrocardiograms. Two case reports are appended. All the previously published cases of pre‐excitation in children are presented in tabular form.

CHANGES IN SKIN TEMPERATURE OF THE NEONATE AT BIRTH.: A cine-thermographic study

The principal mechanism of controlling heat loss during the first postnatal hour is the constriction of skin vessels, thus reducing radiation and the temperature gradient between skin and environment (2, 4). Because of lack of suitable methods, our knowledge is only fragmentary concerning the immediate response of the peripheral circulation at birth. Thermography offers a method to map out the heat distribution of the skin and by cinethermography sudden changes in temperature can be recorded almost continuously.

Catecholamine Excretion in the Newborn Period: Effect of Short Periods of Induced Hypoxial

The response of the newborn to induced anoxia is a many faceted one. Cross et al. (5, 6) reported that a reduction in the oxygen content in the inspired air from 20 % to 15 % caused a fall in 0, consumption in newborn term and premature infants. Cross and co-workers have further shown that, in response to the administration of 15% 02, premature and full term infants show only a transitory hyperventilatory response which returns to its initial level after approximately two minutes (7). Rowe & James produced changes in pulmonary arterial pressure as well as a fall in the arterial oxygen saturation in a newborn infant by the administration of a gas mixture containing 15 % oxygen, though the effects were more striking when the oxygen content was lowered to 10 % (21). Asphyxia, produced by tracheal compression, has been found to result in intense activation of the adrenal medulla in animals. Rapela t Houssay observed a striking increase in the secretion of the adrenal medulla of the dog in asphyxia (20), similar findings were recorded in the cat by Euler & Folkow (12). In both studies the percentage of noradrenaline in the suprarenal venous blood was similar to the resting state. It has also been suggested by Dawes and co-workers that the release of catecholamines in response to asphyxia provides an alternative method of closure of the ductus arteriosus in newborn lambs (9). (Paradoxically the other stimulus to closure is an increase in oxygen tension.) Clinically, Englesson, Rooth & Sjostedt have recently proposed the routine use of 15% oxygen as a milieu for premature infants on the supposition that such a mixture is more suited physiologically to their metabolic requirements (11). The following study was undertaken in order to evaluate the possible relationships between the administration of a reduced oxygen mixture and the excretion of noradrenaline and adrenaline in the newborn infant. Coincident with the above, the study afforded an opportunity to assess normal dopamine excretion in the newborn period. Aided by grants from the Association for

Roentgenologic Determination of Heart Volume in Infants.1

Roentgenologic determination of the heart volume has been carried out in 45 infants with healthy hearts. The roentgenograms were taken simultaneously in two planes at right angles (the frontal and sagittal planes), and the volume calculated by Jonsells modification of the Kahlstorf formula. In order to ascertain the error of the method a number of control examinations were made on cadavers, and in addition double determinations were made in 18 infants at the time of the roentgen examination. The absolute values for the heart volume were correlated with the body length and the body‐weight and the heart volume per square metre of body surface with the body length.