Blood Volume in Newborn Piglets: Effects of Time of Natural Cord Rupture, Intra-Uterine Growth Retardation, Asphyxia, and Prostaglandin-Induced Prematurity
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Pediatr. Res. 15: 53-57 (1981) asphyxia natural cord rupture blood volume prostaglandin F 2 intra-uterine growth retardation Blood Volume in Newborn Piglets: Effects of Time of Natural Cord Rupture, Intra-Uterine Growth Retardation, Asphyxia, and Prostaglandin-Induced Prematurity 137 OTWIN LINDERKAMP, , KLAUS BETKE, MONIKA GUNTNER, GIOK H. JAP, KLAUS P. RIEGEL, AND KURT WALSER Department of Pediatrics and Department of Veterinary Gynecology, University of Munich, Munich, Federal Republic of Germany Summary (27, 29, 32). Placental transfusion is accelerated by keeping the infant below the placenta (19, 27), by uterine contractions (32), Blood volume (BV), red cell mass (RCM; Cr-51) and plasma 125 and by respiration of the newborn (19). Placental transfusion is volume ( 1-labeled albumin) were measured in lOS piglets from prevented by holding the infant above the placenta (19, 27), by 28 Utters shortly after birth. Spontaneous cord rupture in healthy maternal hypotension ( 17), by tight nuchal cord ( 13), and by acute piglets occurred during delivery (n • 25) or within 190 sec of birth intrapartum asphyxia (5, 12, 13). Intra-uterine asphyxia results in (n • 82). Spontaneous and induced delay of cord rupture resulted prenatal transfusion to the fetus (12, 13, 33). In a time-dependent Increase in BV and RCM. BV (x ± S.D.) at It is to be assumed that blood volume in newborn mammals is birth was 72.5 ± 10.5 ml/kg (RCM, 23.6 ± 4.6 ml/kg) In the 25 similarly influenced by placental transfusion as in the human piglets with prenatal cord rupture and 110.5 ± 12.9 ml/kg (RCM, neonate. Indeed, late clamping of the umbilical cord markedly 38.4 ± 7.0 ml/kg) In 17 piglets with late spontaneous cord rupture. increases the blood volume of the newborn lamb (34). Prenatally The mean blood volume of all the 107 healthy piglets with spon induced hypoxia in the lamb results in placental transfusion to taneous cord rupture was 90.2 ± 12.7 ml/kg (RCM, 30.1 ± 4.8 the fetus before birth (18, 35). Moreover, maternal hypotension ml/kg). RCM was significantly (P < 0.05) Increased In nine piglets impedes placental transfusion to the lamb (7). with Intra-uterine growth retardation (RCM, 35.8 ± 11.2 ml/kg) No animal studies have been found in the literature concerning and In 13 with metabolic acidosis but without signs of asphyxia naturally occurring factors which might affect neonatal blood (RCM, 35.8 ± 6.7 ml/kg). In five piglets with cord wrapping, volume such as the time of spontaneous cord rupture, intra-uterine prenatal cord rupture, and acute asphyxia, BV (57.8 ± 7.3 ml/kg) growth retardation, acidosis, asphyxia, or cord wrapping. In the was significantly decreased. In five other piglets with prenatal cord present study, we measured the blood volume of 164 naturally rupture and acute asphyxia, BV (67.9 ± 10.0 ml/kg) corresponded born, full-term piglets and 41 premature piglets. to that of the normal piglets with prenatal cord rupture. However, delay of cord rupture to 60 sec after birth did not Increase BV (66.0 ± 11.8 ml/kg) in four piglets with acute asphyxia. Forty-one ANIMALS premature piglets delivered 6 days before normal term had their Two hundred five vaginally delivered newborn piglets from 28 cords ruptured prenatally or within 5 sec of birth. Their hematocrit litters were included in the study. They were products of healthy at birth (0.337 ± 0.028 liters/liter) was significantly decreased nulliparous German landrace sows with accurately timed gesta compared to the normal full-term piglets with corresponding time tion. All piglets were delivered while the sow was in lateral of cord rupture (0.384 ± 0.033 liters/liter). RCM in 18 piglets with recumbency. The time taken for the umbilical cord to rupture prostaglandin-Induced prematurity (18.9 ± 3.4 ml/kg) was signifi after delivery was recorded. cantly lower than In 23 piglets whose births had been Induced by One hundred fifty-four piglets were born at term with a gesta ovarectomy of their mothers (RCM, 22.1 ± 3.2 ml/kg). tional age of 114 to 116 days. The full-term piglets were divided into four main groups. Speculation Group I consisted of 128 normal piglets. In 25 of these piglets (group Ia), the cords had broken before birth, this frequently There is a great variabillty of placental transfusion in piglets occurs in piglets (22). In 82 piglets, cords ruptured spontaneously (average, 24%; range, 0 to 60% of fetal blood volume) because 6 to 190 sec after delivery (groups Ib to If). In 11 piglets, the intact natural cord rupture occurred at any time from sub partu to 3 min cords were ruptured by one of us within 5 sec of birth (group Ig). after birth. This impUes that hypo- or hypervolemia per se, in the In l 0 piglets, cord breakage was prevented by holding them tight otherwise well adapted newborn, must not represent a pathologic on the floor close the introitus vaginae without drawing the condition. On the other hand, in the newborn with abnormal umbilical cord. Their cords were ruptured at 3 min after birth adaptation to extra-uterine life, abnormal blood volume may be (group lh). carefully considered as either cause or consequence of maladap Group II were nine piglets with intra-uterine growth retarda tation requiring appropriate treatment. tion. Their weights ranged from 570 to 800 g. Two had their cords broken before birth, and seven by us within 5 sec of birth. Thirteen apparently healthy piglets with severe metabolic aci Neonatal blood volume largely depends on the direction and dosis at birth (base excess below -10 mmoles/liter), but without magnitude of perinatal transfer of blood between the fetus and signs of asphyxia, were assigned to group III. Time of cord the placenta. The effects of various factors on blood volume in the severage varied between prenatal and 3 min after birth (Fig. 3). human neonate have been extensively studied. In normal newborn Group IV consisted of 14 severely asphyxiated piglets. They infants, blood volume increases with the time of cord clamping showed no respiratory efforts. Heart rate was below 100 beats/ 54 LINDERKAMP ET AL. min (normal values measured in 20 normal piglets shortly after piglets. The labeled compounds were injected via a peripheral birth, 213 ± 41 beats/min). Muscle tone was flaccid, and skin vein. Six blood samples of 1.0 ml were taken from an umbilical color was pallid or cyanotic. The viability score adapted from the venous catheter at 5, 10, 20, 30, 45, and 60 min after injection of Apgar score (21) was below 5. The asphyxiated piglets were the tracers and analyzed for hematocrit and for radioactivity in a resuscitated by pharyngeal suction, bagging with 100% oxygen well-type scintillation counter (Frieseke & Hoepner, Erlangen inhalation, and cardiac massage immediately after cord rupture. Bruck, Federal Republic of Germany). The counts of the tracers Five asphyxiated piglets had their cords wrapped around the body were retropolated to the time of their injection. Inasmuch as 1251- or a limb (group IVa). Their cords had broken before delivery. labeled human albumin is a heterologous protein, plasma volume The other nine piglets were either born with ruptured cord (group measurements in nine piglets were also made with Evans blue (II) IVb; n ,. 5) or the cords were ruptured by us at 60 sec after birth which combines with autologous albumin in vivo. No significant (group lYe; n = 4). Thus asphyxia was often associated with cord difference was found in any of the parameters measured with the entanglement and prenatal cord rupture. This agrees with the two markers (Table 1). Mixing time of labeled albumin and red ftndings of Randall (23, 25). cells, disappearance rate of labeled albumin, body /venous hema Forty-one piglets were delivered at 109 days of gestation. In two tocrit ratio, and the errors of analyzing the counts of a single sows, termination of pregnancy was induced by ovarectomy per blood sample taken 10 min after injection of 51 Cr-labeled red cells formed at 107 days of gestation. The sows were anesthetized with and 5 min after injection of 1261-labeled albumin and Evans blue Metomidat-HCI (2.5 mg!kg) (Hypnodil) and Azaperon (0.6 mgl were calculated as previously described (10, II). The results of the kg) (Stresnil) intravenously. In addition, low spinal anesthesia was methodological studies are summarized in Table I. obtained with 10 ml of 2% lidocain. Farrowing began 41 and 42 Based on these studies, plasma volume in the other 125 piglets hr, respectively, after ovarectomy (group V; n = 23). In three sows, was measured by analyzing a single blood sample 5 min after the parturition was induced by intramuscular administration of 10 mg injection of 1251-labeled albumin, and blood volume and red cell of prostalene (Synchrocept; Syntex, Den Haag, Netherlands), mass were calculated from plasma volume, hematocrit, and the which is an analogue of prostaglandin F2o (6). The drug was given body /venous hematocrit ratio of 0.84. at 108 days of gestation and farrowing initiated 24 to 29 hr Blood volume was measured 60 min after birth because the later (group VI; n = 18). Four piglets of the group V and four of procedure of tagging red cells with 51Cr in vitro required 50 min. the group VI were severely asphyxiated, had viability scores (21) Blood volume at birth was calculated from hematocrit, red cell below 5, and required vigorous resuscitation. The birth weights of mass, and the body /venous hematocrit ratio of 0.84. This proce the premature piglets (Table 2) corresponded to their gestational dure appears reasonable as studies in human neonates (29) and in age (I).