产程中胎儿安全监测

产程中胎儿监测方法主要有胎心听诊,胎儿电子监护、胎儿血气分析及胎儿脉冲血氧测定等,上述方法的合理应用,能及时判定胎儿有无缺氧,以便适时干预,从而保障胎儿在产程中的安全。     

Monitoring of transcutaneous PO2 in the fetus and mother during normal labor

Transcutaneous PO2 (tcPO2) measurement is a non-invasive method which gives continuous information about central PO2. The method has previously been testes primarily on newborns and adults, and reports on the applicability of the method on the fetus during labor are still scanty and restricted to case reports. This paper reports on a systematic study of intrapartum fetal and maternal tcPO2-monitoring. The material is comprised of 19 parturients, the majority being nulliparae. All fetal presentations were vertex. The tcPO2 recordings averaged one hour in duration (Tab. I). FHR was recorded simultaneously. In 12 cases the electrode was affixed with glue, and in 7 cases a suction device was used for fixation. The electrode was attached when the cervix was dilated 4 to 6 cm. The mean tcPO2 was 20 mm Hg in the beginning of the registration, and showed a small decline in level throughout labor reaching 14 mmHg at the end of the registration period (Fig. 5). These values are in good agreement with those found by other authors in previous investigations. In some of the present cases, very low tcPO2 values were recorded. The relevance of these low tcPO2 values is unclear, and it is impossible to determine to what extent these tracings have true physiological relevance versus might be due to technical factors.     

Induction of labor in the postdate fetus

Once a decision to induce a postdate pregnancy is reached, the likelihood of achieving a vaginal delivery can be predicted by the Bishop or pelvic score and the willingness or lack thereof to commit to sequential inductions. Cesarean delivery rates will be significantly increased if an amniotomy is performed in the woman with an unfavorable cervix. Accordingly, we advocate sequential induction of the postdate pregnancy in the absence of other maternal or fetal mandates for imminent delivery. A host of oxytocin induction protocols exist and are acceptable, as are guidelines for what constitutes an adequate labor pattern. Although an increasing number of agents are available for cervical ripening, for the foreseeable future dilute intravenous oxytocin will remain the labor induction agent of choice.     

Monitoring the IUGR fetus

Monitoring of the intrauterine growth retarded fetus in order to improve fetal outcome and define precisely the timing of delivery, when necessary, is based on the study of changes in vital functions observable in cases of hypoxemia. It is easy to believe that ultrasound equipment with Doppler facilities is present in the majority if not in all gynecological units. Cardiotocography is also widely used and the addition of a computerized evaluation system is not expensive and therefore should be available when facing high risk pregnancies such as intrauterine growth retarded cases. IUGR can be recognized through the use of ultrasound fetal biometry and clinical examination of maternal conditions in order to assess fetal conditions. If the above technologies are available further action, such as fetal Doppler study of fetal vessels and cardiotocography, can then be undertaken. In this paper, we will be discussing the issue of monitoring the fetus for fetal well-being, particularly in cases of intrauterine growth retarded fetuses.     

Intrauterine resuscitation during labor: review of current methods and supportive evidence

When the fetal heart rate pattern is suggestive of fetal compromise during labor, various methods to promote fetal well-being are traditionally initiated. They include maternal repositioning, reduction of uterine activity, an intravenous fluid bolus, oxygen administration, correction of maternal hypotension, amnioinfusion, and alteration of second-stage labor pushing efforts. Although these intrauterine resuscitation techniques are commonly used, and in some cases considered standard care, supportive data could be more robust. Nevertheless, there is enough evidence to suggest they are beneficial to the fetus and there is minimal risk of harm when used with clinical common sense. Until more data are available, it seems reasonable to err on the side of fetal safety by using these techniques when appropriate, based on the specific fetal heart rate pattern.     

Radiologic evidence of a nuchal arm in the breech-presenting fetus at the onset of labor: an indication for abdominal delivery

The occurrence of a nuchal arm during vaginal breech delivery is a potentially traumatic event associated with high perinatal morbidity and mortality. This problem usually cannot be anticipated and must be overcome immediately on diagnosis during the second stage of labor. The results of a retrospective analysis of radiologic studies of 115 cases of term singleton breech deliveries are presented here. A nuchal arm in the first stage of labor was diagnosed in five cases, an incidence of 4.35%. Of four vaginal breech deliveries, one case resulted in severe handicapping neonatal trauma. We suggest that radiologic diagnosis of a nuchal arm in the first stage of labor should indicate abdominal delivery.     

A practical approach to labor support

In the United States, intrapartum nurses are present at 99% of births. These nurses have a unique opportunity to positively affect a laboring woman's comfort and labor progress through the use of labor support behaviors. These nonpharmacologic nursing strategies fall into four categories: physical, emotional, instructional/informational, and advocacy. Implementation of these strategies requires special knowledge and a commitment to the enhanced physical and emotional comfort of laboring women.     

Transcutaneous carbon dioxide measurements in the fetus during labor

Continuous transcutaneous carbon dioxide partial pressure (tcPco2) was monitored in 40 spontaneous labors. The electrode was attached by glue fixation. An interpretable tracing was obtained in 36 cases. All cases but 2 were normal pregnancies. Thirty-two patients had epidural analgesia while the others had no analgesia. All infants had an Apgar score above 7 at five minutes after delivery and only two had a pH of the umbilical artery of less than 7.16. Mean duration of the recordings was 116 minutes (range: 15-300) and mean time for reaching steady-state was 27 minutes (range: 10-45 minutes). Mean value of tcPco2 was 48 mmHg (SD: 6) before 6 cm of dilatation, 47 mmHg (SD: 8) between 6 and 10 cm, and 47 mmHg (SD: 15) at the second stage of labor. Mean umbilical artery Pco2 was 48 mmHg (SD: 14) and mean umbilical artery pH was 7.25 (SD: 0.06). The range of tcPco2 obtained in these normal cases was 20 to 62 mmHg. Comparison of the results with those of other authors and with previous studies of normal labor and epidural analgesia show a higher tcPco2 compared to scalp Pco2. In contrast to other studies in these series no correlation was found in the series between umbilical artery Pco2 and tcPco2 values. This lack of correlation could be explained either by the small number of cases in which both measurements were available (9 cases) and by the small range of variation or by some inaccuracy in the measurements.(ABSTRACT TRUNCATED AT 250 WORDS)     

Transcutaneous carbon dioxide measurements in the fetus during labor

Transcutaneous partial pressure of carbon dioxide (transcutaneous PCO2) was measured in 55 fetuses during labor with a carbon dioxide electrode applied to the fetal scalp by a suction ring. The application procedure was simple and reliable, with reapplication required only 0.6 times per patient. The transcutaneous PCO2 recordings were of good quality and were correlated to carbon dioxide tensions in the umbilical artery (r = 0.60, p less than 0.001) and vein (r = 0.69, p less than 0.001) as well as to capillary PCO2 obtained by fetal scalp blood sampling (r = 0.96, p less than 0.001). If fetal distress occurred, transcutaneous PCO2 was significantly higher than in the uncompromised fetus. Although transcutaneous PCO2 monitoring might be useful for surveillance of the fetus during labor, it must still be reserved for scientific purposes for the time being.     

Cerebral blood flow during labor in the human fetus

A method is described for recording blood flow velocity waveforms from fetal cerebral vessels during labor, using a 2 MHz pulsed Doppler ultrasound technique. Fifteen healthy women with uncomplicated pregnancies and labor without signs of fetal distress participated in the study. With membranes ruptured and cervix orifice open 4-9 cm, the Doppler transducer was placed transvaginally on the fetal skull and the Doppler shift signals from the middle cerebral artery were located. The maximum velocity waveforms were recorded before, during and after uterine contractions and analysed off-line for pulsatility index (PI). No differences in the PI were found with regard to the uterine contractions. The results suggest an unchanged peripheral resistance in the fetal cerebral vascular bed during the first stage of normal labor.     

Social support during premature labor: effects on labor and the newborn

Prematurity is the single most frequent abnormality associated with birth, and is associated with both neonatal deaths and developmental deficits. In uncomplicated labors at term, the presence of a supportive companion has been found to lead to reduced length of labor, reduced need for medication for pain management, and improved neonatal well being. The relationships have not been explored in premature labor. Women in premature labor between 26 and 37 weeks of gestation were randomly assigned to a control group (n = 11) or to a supported group (n = 14), who were accompanied during labor by a supportive companion. Support during labor was associated with fewer abnormally long labors, less frequent use of medication for pain management during labor, and improved neonatal wellbeing.     

Beneficial impact of term labor: nonenzymatic antioxidant reserve in the human fetus

OBJECTIVE: Oxidative stress occurs when the production of damaging free radicals and other oxidative molecules exceeds the capacity of the body's antioxidant defenses. Oxidative stress is implicated in diseases that are associated with prematurity (such as retinopathy, cerebral palsy, intraventricular hemorrhage, and necrotizing enterocolitis). Nonenzymatic antioxidant reserve is the first line of defense against free radicals. We hypothesized that an in utero redox imbalance because of stress would diminish the fetal antioxidant reserve. We tested aspects of this hypothesis by investigating whether the presence of labor or gestational age at delivery (term vs preterm) alters the maternal/fetal nonenzymatic antioxidant reserve peripartum. STUDY DESIGN: Fetal redox consumption was calculated from the difference in the nonenzymatic antioxidant reserve that was measured in umbilical venous and arterial blood that was collected prospectively at delivery from 39 newborn infants. Eight women were delivered at term by elective cesarean delivery in the absence of labor; 31 women labored either at term (n = 20) or preterm (<37 weeks, n = 11). Maternal venous blood was collected on admission and within 1 hour of delivery. Nonenzymatic antioxidant reserve was measured in the plasma and red blood cells of each specimen by the quantitation of glutathione content (glutathione in red blood cell lysate) and the plasma total free radical-trapping antioxidant potential. Glutathione was measured with the use of a colorimetric assay and expressed in nanomoles per milligram of hemoglobin. The plasma total radical-trapping antioxidant potential was estimated with the use of a controlled, kinetic assay based on the time that was required to inhibit peroxyl-free radical generated under controlled conditions. The differences between both umbilical venous and umbilical arterial total radical-trapping antioxidant potential and glutathione were computed to estimate fetal nonenzymatic antioxidant reserve consumption. The differences between maternal total radical-trapping antioxidant potential and glutathione before and after delivery were computed to estimate maternal peripartal nonenzymatic antioxidant reserve consumption. RESULTS: Fetal red blood cell glutathione content was significantly greater than maternal red blood cell glutathione content, independent of delivery route. The calculation of the fetal nonenzymatic antioxidant reserve consumption and maternal peripartal nonenzymatic antioxidant reserve consumption revealed that women who labored at term experienced an up-regulation in red blood cell glutathione content, while their fetuses had significantly lower red blood cell glutathione consumption. In contrast, there was consumption of plasma antioxidants in preterm fetuses, as illustrated by a doubling of the fetal nonenzymatic antioxidant reserve consumption (elective cesarean delivery in the absence of labor, 0.9 +/- 0.5 min/microL; term labor, 1.0 +/- 0.1 min/microL; preterm labor, 2.0 +/- 0.4 min/microL; one-way analysis of variance; P =.04). This was mostly due to a lower umbilical arterial total radical-trapping antioxidant potential in preterm versus term fetuses (umbilical arterial, 3.3 min/microL versus umbilical venous 5.4 min/microL; paired t test; P =.001; power, 0.98). Generally, maternal total radical-trapping antioxidant potential remained unchanged peripartum. CONCLUSION: Term labor triggers a compensatory up-regulation of nonenzymatic antioxidant reserve in the fetal red blood cell compartment that may act to protect against the relative hyperoxia that is experienced by the newborn infant at birth. In contrast, the decreased nonenzymatic antioxidant reserve in the fetal red blood cell and plasma compartments after preterm labor and delivery would enhance the vulnerability to free radical damage of the preterm neonate. These findings suggest that the two compartments of nonenzymatic antioxidant reserve have distinct physiologic roles in the peripartal defense against free radicals and that their development is, in some fashion, ontogenes, in some fashion, ontogenetically regulated.     

MASA syndrome: ultrasonographic evidence in a male fetus

The recent identification of a common etiology among MASA syndrome (McKusick 303300), X-linked hydrocephalus (HSAS) (McKusick 307000) and other related neurological disorders, which had previously been considered distinct nosological entities, allowed us to diagnose MASA syndrome in a male fetus in a primigravida at the 29th week of gestation by sonographic signs of the MASA spectrum such as hydrocephalus and hypoplasia of corpus callosum. Indeed, the evidence of an X-linked neurological disease in the brother and the maternal uncle of the pregnant women enabled us to estimate a 25% risk of a male fetus being an affected hemizygote. The way in which a prenatal diagnosis, based on instrumental procedures, was reached is described since the authors were unable to perform, at the time of the observation, a molecular confirmation which was carried out only after birth.