الفهرس 
COVEROnly 14 pages are availabe for public view
 |  | from | 157 |  |  |
| | | from | 157 | | |
Abstract
Asphyxia is a condition of impaired gas exchange, which when persistent, leads to progressive hypoxemia and hypercapnia. During normal labor, uterine contractions cause temporary reductions in gas exchange. After the contraction, fetal compensation occurs with self-resuscitation, followed by normal perfusion until the next contraction occurs. If these natural physiologic compensatory mechanisms are overwhelmed, hypoxic acidemia ensues. Hypoxic acidemia of a sufficient degree and duration can cause brain damage with resultant neurological squeals in surviving children, other organ system damage, or intrapartum or neonatal death.
Historically, asphyxia was diagnosed by a low one-minute and five-minute Apgar score. This was not a reliable criteria because only 30 to 40 percent of newborns who are depressed (i.e. have low Apgar scores) at birth are acidotic at delivery, which suggests that the depression is related to factors other than prolonged hypoxia such as congenital anomalies, preterm birth, and administration of drugs to the mother. So, using of the Apgar score in diagnosis of perinatal asphyxia is a misuse of this scoring system. On the other hand, cord blood gas analysis provides an objective measure of neonatal condition at birth, as opposed to the Apgar score which is subjective.
Oxytocin is of enormous benefit to women in labor with poor progress. This holds true for both nulliparous and parous women. Nevertheless, serious complications in the mother and fetus have been reported after infusion of oxytocin, and oxytocin is a frequent issue in obstetrical malpractice claims.
This study was designed to estimate the unfavorable effect of oxytocin on the fetus as a possible cause of perinatal asphyxia by comparing the values of the umbilical cord blood gases obtained immediately after delivery as well as Apgar score at the 1st and the 5th minute after delivery in cases diagnosed as primary failure of progression of labor augmented with oxytocin and un-augmented labors.
The study was carried out on one hundred and fifty three pregnant women in the first stage of labor fulfilled the selection criteria mentioned in the protocol, and the selection was from the pre-labor ward of Ain-Shams Maternity Hospital (ninety one women) and El-Sahel Teaching Hospital (sixty two women) after their acceptance and signing the appropriate consent.
As regards the definition of primary failure of progression of labor mentioned in the protocol, those women were divided into two groups. The first group was seventy nine women, who fulfilled the selection criteria, were diagnosed as primary failure of progression in labor due to hypo-contractile uterine activity and managed by augmentation of labor using oxytocin (cases or group A). The other group was seventy four women also fulfilled the selection criteria but were not managed by augmentation of labor using oxytocin (controls or group B).
The newborns of all patients were evaluated using Apgar score at the 1st and 5th minutes after delivery by the same observer.
Umbilical cord blood samples were obtained from all patients. Two samples were obtained from the umbilical cord, one from the artery and the other from the vein. Estimation of pH, PO2, PCO2, HCO3 and base excess of both samples was done.
The results of the study were tabulated and statistically analyzed using standard statistical tests.
The results of this study showed that oxytocin has significant effects on certain variables of the umbilical artery blood gases (pH, base excess and PCO2 but not PO2). This effect is so mild that does not affect the neonatal general conditions.
There were significant differences between the case and control groups as regards pH and base excess. The case group had a lower mean value in the both variables. It means that the umbilical artery samples of the case group are more acidotic than those of the control group. It indicates that the use of oxytocin in actively managed labors will put the fetus under more stress than that if oxytocin was not used.
On the other hand, when we put the readings of umbilical artery pH and base excess of both case and control groups in ranges according to the definitions of perinatal asphyxia mentioned in different studies, there was a non-significant difference between both groups as regards these pH and base excess ranges. It indicates that the use of oxytocin in actively managed labors will not put the fetuses under that stress that causes perinatal asphyxia.
There was no difference between the case and control groups as regards Apgar scores at the 1st and 5th minutes. It indicates that the use of oxytocin in the actively managed labors will not affect the neonatal general conditions unless there is another cause causing low Apgar score as prematurity, maternal disorder or instrumental delivery.
As regards the whole study population, there were high significant correlations between both pH and base excess, and Apgar scores at the 1st and 5th minutes. These results could be explained under the fact that most of causes that affect the neonatal general conditions were excluded. Thus, the perinatal asphyxia, in this study, is almost the only cause of low Apgar score.