Neonatal effects of the delivery interval during cesarean section under spinal anesthesia

The relationships between I-DI (induction to delivery interval) or U-DI (uterine incision to delivery interval) and fetal acid-base status or neonatal clinical condition were studied in 60 healthy parturients undergoing elective cesarean section under spinal anesthesia. The patients were divided into groups, i.e. group A (U-DI less than 90 sec, I-DI greater than 14 min, 18 cases), group B (U-DI less than 90 sec, I-DI greater than 14 min, 12 cases), group C (U-DI greater than 90 sec, I-DI less than 14 min, 15 cases) and group D (U-DI greater than 90 sec, I-DI greater than 14 min, 15 cases). Acid-base values for maternal arterial (MA), umbilical venous (UV) and umbilical arterial blood (UA), and acid-base gradients for (MA-UV) and (UV-UA) in each group were all in the normal range and revealed no significant differences among 4 groups, though U-DI was correlated with UVPCO2, UAPCO2, and (UV-UA) base deficit (r = 0.322, 0.266, -0.256: p less than 0.05). Acid-base states in cases of long and excessively long U-DI (greater than 90 sec and greater than 150 sec, respectively) were more acidotic than those of short U-DI groups (less than 90 sec). Both 1 and 5 minute Apgar scores were 8 or more in all neonates. There was no correlation between I-DI and fetal acid-base values or neonatal clinical conditions. It is conceivable that gentle and careful manipulations of the uterus and fetus rather than shortening of U-DI might be important in preventing against fetal or neonatal depression during cesarean section under spinal block.     

The maternal and fetal acid-base status during general or spinal anesthesia for elective cesarean section in the left tilt position

Thirty one healthy parturients received spinal or general anesthesia for elective cesarean section. Maternal blood pressures, maternal and fetal acid-base values, induction to delivery intervals (I-DI) and Apgar scores were determined. On spinal anesthesia, acute hydration by 6% hydroxyethyl starch solution and intramuscular injection of ephedrine were enforced prior to the block and in the left tilt position (17 degrees) oxygen inhalation immediately after the block was begun (group OII: 16 cases). As to general anesthesia, the same left tilt position was applied before the anesthesia by thiopental-0.5% halothane with-50% nitrous oxide in oxygen (group G: 15 cases). No significant decrease in maternal blood pressure was noticed, and maternal and the fetal acid-base status and Apgar scores were excellent in both groups. A positive correlation between umbilical venous pH values and 1 or 5 minutes Apgar scores was confirmed in group OII, and a negative correlation between 1 minute Apgar scores and I-DI was noticed in group G. Fetal acid-base values were not correlated with I-DI in either group, and it was postulated that placental or fetal circulation was sufficiently maintained. Biochemical status and clinical conditions in mothers and their infants are very favorable in well-conducted general or spinal anesthesia for elective cesarean section.     

Fetal acid-base and neonatal status after general and neuraxial anesthesia for elective cesarean section.

OBJECTIVE: To analyze the relation between fetal acid-base and neonatal status in an observational cohort study of 900 consecutive women with singleton pregnancies at term undergoing elective cesarean section. METHODS: The women were divided into 3 groups according to the type of anesthesia administered. Fetal acid-base status was assessed from umbilical cord blood (both artery and vein) and intermediate neonatal outcome was noted. RESULTS: Epidural anesthesia was associated with the highest pH. The lowest pH and the highest pC0(2) values were associated with spinal anesthesia. Although maternal general anesthesia was associated with the highest values for partial pressure and saturation of oxygen in umbilical arterial blood, the newborns were more likely to be depressed than those born following spinal (P=0.0016) or epidural (P=0.0002) anesthesia. CONCLUSIONS: If fetal oxygenation is the goal, general anesthesia provides the highest values for partial pressure and saturation of oxygen in umbilical arterial blood. However, epidural anesthesia was associated with better fetal and neonatal status than either spinal or general anesthesia.     

A comparison of the effect of epidural, general, and no anesthesia on funic acid-base values by stage of labor and type of delivery

The effect of epidural anesthesia on neonatal acid-base status, before, during, and after labor, was determined by review of funic blood-gas values from 142 women with normal term pregnancies and normal fetal heart rate patterns. Funic acid-base parameters were compared by type of anesthesia when stratified by mode of delivery (vaginal, cesarean section in the active phase of labor, or elective cesarean section). Use of epidural analgesia for vaginal delivery was associated with significantly longer labor, lower umbilical arterial pH, higher arterial PCO2 and arterial bicarbonate values. In women who had cesarean section in the active phase of labor, use of epidural anesthesia was associated with significantly lower arterial and venous PO2 values when compared with women who received general anesthesia. Patients who had elective cesarean section with epidural anesthesia had funic acid-base values similar to women who had general anesthesia. Epidural analgesia-anesthesia offers no clear advantage to the uncompromised term fetus.     

Cord sampling for the evaluation of oxygenation and acid-base balance in growth-retarded human fetuses

In 14 pregnancies complicated by intrauterine growth retardation, the umbilical cord was sampled before delivery under ultrasonic guidance for rapid fetal karyotyping. Fetal blood was analyzed for respiratory gases, acid-base balance, and lactate concentrations. Two patients were excluded from the study because cord samples were diluted with amniotic fluid. In six patients (group 1), the clinical assessment warranted continuation of pregnancy. Cesarean sections were performed in the remaining eight patients (group 2) within 8 hours of cord sampling. The data from the two groups were compared with those obtained from umbilical venous blood at the time of elective repeat cesarean section in term appropriate for gestational age infants (controls). No significant difference in PO2 was found between groups 1 and 2 and controls. In contrast, there were significant differences in oxygen saturation and acid-base balance between groups 1 and 2. Lactate concentration was inversely correlated with pH and was elevated in five of six fetuses requiring a prompt cesarean section: In two of these five fetuses, nonstress fetal heart rate tracings were reactive. The results suggest that fetal blood biochemistry, and particularly lactate concentration, may represent an additional indicator of fetal well-being in pregnancies complicated by intrauterine growth retardation.     

Anesthesia for cesarean section: further studies.

This study was designed to re-evaluate neonatal condition at birth following elective cesarean section performed with epidural anesthesia and a modified technique of general anesthesia. Two groups of 20 patients were studied. Twenty received epidural anesthesia with 2 per cent lidocaine-carbon dioxide-epinephrine, and 20 patients were given general anesthesia. Modifications of our previous general anesthetic technique included the administration, to the mother, of high inspired concentrations of oxygen (66 per cent) prior to delivery, short induction-to-delivery intervals, and positioning of the mother in a 20 degrees left lateral tilt position. No significant differences in oxygen tension and acid-base balance in umbilical venous and arterial blood were demonstrated between the two sets of neonates. One-and five-minute Apgar scores and time to sustained respiration were similar in both groups. Our observations of the infants immediately after delivery led us to conclude that either anesthesia technique is acceptable for elective cesarean section.     

Use of intravenous fluids before cesarean section: effects on perinatal glucose, insulin, and sodium homeostasis

Perinatal glucose, insulin, and sodium homeostases were assessed in relation to antepartum intravenous infusions administered to 59 normal mothers undergoing cesarean section at term without labor under epidural anesthesia. Group A (N = 20) received 1 L of Ringer's lactate without dextrose during one hour; group B (N = 20), 1 L of 5% dextrose in water during one hour; and group C (N = 19), 1 L of 5% dextrose in water during two and one half hours. Mean maternal and fetal serum glucose and insulin and sodium concentrations at delivery differed among all groups in direct relationship to the rate of glucose infusion. Neonatal hypoglycemia (30 mg/dL or less) correlated with the presence of a glucose infusion, a maternal glucose concentration of 117 mg/dL or greater, and an umbilical venous insulin concentration of 26 microU/mL or greater. Among group A patients who received sodium, and group B and C patients who did not, fetal hyponatremia (umbilical venous sodium 130 mEq/L or less) correlated with the absence of sodium in the prepartum infusion. The results suggest that the antepartum administration of a balanced electrolyte solution without excess glucose infusion can minimize the incidence of fetal hyperglycemia and hyponatremia and neonatal hypoglycemia.     

Amyl nitrite: use as a smooth muscle relaxant in difficult preterm cesarean section.

Amyl nitrite is a smooth muscle relaxant that has been used clinically to facilitate uterine relaxation in difficult deliveries. In this retrospective study, we evaluate the safety of amyl nitrite use during preterm cesarean deliveries, and we assess possible advantageous effects on surgical incision choice. Women who received amyl nitrite cesarean section were compared to a control group matched for gestational age, fetal presentation, and mode of delivery who did not receive amyl nitrite. There were no statistical differences between the groups in the independent variables (maternal age, parity, medical or obstetric history, type of anesthesia, anesthesia or obstetric attending physician, antepartum hematocrit, or neonatal weight). Outcome (dependent) variables (estimated blood loss, Apgar scores, postpartum hematocrit, cord gases, or postpartum complications) were assessed, and there were no significant differences between the groups. Low transverse cesarean section was performed more frequently in the amyl nitrite group (58 of 64) than in the comparison group (48 of 64) (p less than 0.03). Considering the 128 women with and without amyl nitrite together, the decrease in hematocrit observed postpartum was greater after classic section (7%) than after low transverse section (4%) (p less than 0.002). We conclude that the use of amyl nitrite during preterm cesarean section poses no threat to mother or fetus and may facilitate delivery by allowing the performance of a low transverse rather than a classic cesarean section without maternal or neonatal complications.     

Fetal and maternal plasma catecholamine levels at elective cesarean section under general or epidural anesthesia versus vaginal delivery

Fetal and maternal plasma levels of catecholamines were measured at birth in 40 women with normal term pregnancies who underwent elective cesarean section. Twenty women were operated on under general anesthesia, and 20 under epidural anesthesia. For comparison, the same measurements were also made in 10 women who underwent vaginal delivery without signs of intrapartum fetal distress. Maternal venous levels of catecholamines were elevated in all three groups as compared to values in the resting adult. The highest levels were found in the vaginal delivery group (norepinephrine and epinephrine, 3.9 ± 2.1 and 1.1 ± 1.0 nmoles/L, respectively), and the lowest in the epidural cesarean section group. Fetal outcomes were similar in all three groups, as judged by Apgar scores and by measurements of umbilical arterial blood gases. In spite of that, neonates delivered vaginally showed a markedly higher sympathoadrenal activation (norepinephrine and epinephrine, 31.8 ± 24.1 and 5.1 ± 7.6 nmoles/L, respectively) than those born by elective cesarean section. In the latter group, however, it was found that the type of maternal anesthesia influenced fetal sympathoadrenal activation, since neonatal levels of catecholamines were higher in the epidural section group (norepinephrine and epinephrine, 9.5 ± 6.4 and 4.0 ± 4.5 nmoles/L, respectively) than in the general anesthesia group (norepinephrine and epinephrine, 3.2 ± 2.7 and 1.0 ± 1.4 nmoles/L, respectively). These results may have a certain clinical relevance since fetal sympathoadrenal activation is thought to promote extrauterine adaptation.     

Effect of induction of general anesthesia for cesarean section on intervillous blood flow.

Intervillous blood flow was measured by a new intravenous 133Xe method before and during induction of general anesthesia for cesarean section in 10 healthy mothers. The flow values showed a highly significant decrease (p less than 0.001) (35 per cent on an average) at the time of anesthesia compared with the control values. The impairment was observed in all the cases. The role of the maternal changes in hemodynamic parameters and acid-base balance as a background of this decrease is discussed.     

Does fetal acidosis develop with maternal glucose infusion during normal labor?

The actual effects of glucose infusion on fetal acid-base status were studied during 125 normal deliveries in which plasma glucose and acid-base parameters were determined after maternal infusion of either 10% glucose or Ringer's solution. After 80 minutes, mean (+/- SD) plasma glucose levels were significantly higher in the glucose group (N = 59) than in the Ringer's group (N = 66), both for the mother (183.6 +/- 46.8 versus 95.3 +/- 18.0 mg/dL) and the fetus (108.4 +/- 41.4 versus 64.8 +/- 16.2 mg/dL). Fetal plasma lactate concentrations did not differ between the glucose and the Ringer's groups, but were significantly lower in the fetuses delivered by elective cesarean section in both groups. With glucose administration, fetal pCO2 was higher and pH values were lower than in the Ringer's group. However, the magnitude of acid-base status changes, indicated by both pH and pCO2 shifts (ie, the difference between umbilical artery and scalp values), failed to differ between the two groups. In fetuses with progressing hypoxia, no differences in any of the acid-base parameters were observed between glucose and Ringer's administration. These data indicate that at a glucose infusion rate of 30 g/hour, fetal acidosis, when it occurs, results from hypoxia rather than from maternal glucose administration.     

Umbilical amino acid uptake at increasing maternal amino acid concentrations: effect of a maternal amino acid infusate.

OBJECTIVE: Our purpose was to establish whether, in normal human pregnancies, the maternal intravenous infusion of amino acids can increase fetal amino acid uptake and amino acid concentrations. STUDY DESIGN: Twenty-six normal pregnancies were studied at the time of cesarean delivery (38-40 weeks' gestation). In 10 cases an amino acid formulation (Freamine 8.5% III, Baxter) was infused into a maternal vein before cesarean delivery. Maternal blood samples were obtained during the course of the study. Umbilical venous and arterial samples were obtained from the clamped segment of the cord. There were no differences between the 2 groups for fetal and placental weights and for fetal oxygenation and acid-base balance. RESULTS: Maternal amino acid concentrations increased significantly in the group receiving infusions. Significant increases in umbilical venous concentrations were observed for most amino acids, except for histidine and threonine. The amino acid umbilical arteriovenous differences per mole of oxygen (AA/O(2) ratio) increased significantly for leucine, isoleucine, valine, methionine, phenylalanine, arginine, glycine, serine, alanine, and proline. There were no significant increases for lysine, histidine, and threonine. CONCLUSION: An increase in maternal concentrations leads to an increase in the delivery of most amino acids to the fetus.     

Uterine and umbilical blood flow during cesarean section under epidural anesthesia

Umbilical and uterine blood flow velocity waveforms were studied in 22 women undergoing elective cesarean section under epidural anesthesia. The measurements were taken prior to initiation of anesthesia (baseline levels), after the appropriate level of anesthesia had been achieved (prior to the onset of surgery), and intraoperatively immediately prior to the uterine incision and after the delivery (uterine blood flow). Achievement of the therapeutic level of epidural anesthesia was not associated with altered umbilical and uterine blood flow. Intraoperatively, however, 2/3 of the women manifested increased resistance in the utero-fetal circuit, judging by the rise in S/D ratios. Under normal circumstances (absence of fetal distress and maternal complications prior to the cesarean section, adequate maternal hydration and oxygenation, etc.) these changes did not cause any neonatal compromise as evidenced by normal Apgar scores and freedom from complications during the neonatal period.     

Pharmacokinetic studies on fenoterol in maternal and cord blood

Fenoterol plasma concentrations were measured by radioimmunoassay in 38 pregnant women at different stages of preterm labor and in cord blood. Eight women were treated intravenously until delivery with 1.0 to 4 micrograms/min of fenoterol for periods ranging from 27 hours to 27 days; blood samples were taken at the same time as cord blood. In these women the fenoterol concentrations in cord blood ranged from 18 to 53% of the maternal concentrations. In eight women treated intravenously with 1.2 to 4.0 micrograms/min for 2 to 15 days, the infusion was stopped 1.3 to 38 hours before delivery. In these instances the concentrations in cord blood reached as much as 90% of the maternal, meaning that the rate of elimination from fetal plasma is lower than that from maternal plasma. Five women were treated daily with 20 to 30 mg per os for 3 to 17 days (three of these women had also had intravenous treatment before). The ratio of cord to maternal blood concentrations was higher than in women receiving the drug intravenously, the relative times of sampling being the same. The findings suggest that: (1) the placental transfer of fenoterol is higher than that found in previous studies in humans and animals with tritium-labeled substances; (2) the rate of fenoterol elimination from fetal plasma after intravenous and oral long-term therapy is lower than that from maternal plasma; (3) after oral administration, the ratios of fetal to maternal fenoterol concentrations are higher than after intravenous infusion.     

Perinatal heart rate variability and circulatory adaptation in association with normal labor and after elective cesarean section

Heart rate variability and basal hemodynamic parameters were studied in connection with 20 normal deliveries and after 16 elective cesarean sections. Eight of the cesarean sections were performed with the use of maternal barbiturate anesthesia and eight with the use of epidural blockade. The interval index describing the long-term variability and the differential index describing the short-term variability of the heart rate were measured continuously from 10-minute samples of a direct fetal electrocardiogram and a neonatal electrocardiogram of the infants by a microprocessor-based system. In association with normal labor, significant increases in both indices of variability were observed during the second stage of labor and during the first 2 hours of extrauterine life. After elective cesarean section both indices of neonatal heart rate variability remained significantly lower than those after normal labor. However, a significant increase was observed in the differential index of the infants delivered with the use of epidural blockade. During the neonatal period, simultaneous recordings of basal heart rate, systolic and diastolic blood pressures, and rectal and heel temperatures were made at 10-minute intervals. The basal neonatal heart rate was significantly higher in both cesarean section subgroups compared with that after normal labor. A significant decrease in basal neonatal heart rate during the second hour of life was observed after normal labor and after cesarean section with the use of epidural blockade. Systolic blood pressures in newborn infants delivered with the use of maternal epidural blockade were equal to those after normal labor, but higher than those after cesarean section with barbiturate anesthesia. Newborn infants after elective cesarean section had significantly lower diastolic blood pressures than infants delivered normally, but there was no difference in the diastolic blood pressures between the two cesarean section subgroups. The infants delivered vaginally had lower heel temperatures than those delivered abdominally. According to the present study, the neonatal circulatory adaptation after elective cesarean section is different from that after normal delivery; however, the neonatal hemodynamics after cesarean section with epidural blockade more closely resemble the situation after normal labor.     

Evaluation of midforceps delivery as an alternative

The fetal intrapartum condition as well as maternal and immediate neonatal outcome of 274 consecutive midforceps rotations (head in transverse or posterior position and below + 1 station but without reaching the perineum) were compared with 106 cesarean sections done for arrest of progress for more than two hours and cervical dilatation of at lest 7 cm. It was found that there were more nulliparous among cesarean section patients, that their fetuses weighed near 400 gm more on the average, and that their time in labor was 200 minutes longer. On the other hand, the midforceps group had a higher incidence of spontaneous labor, conduction anesthesia, and intraprtum fetal distress (37%). There were no differences in fetal outcome, other than admission to NIC and/or NIM among C-section infants. This latter group had a higher postdelivery maternal complication rate (hemorrhage and infection), as well as longer than expected hospital stay. These findings are discussed. It appears that midforceps rotation, properly indicated and executed, offers a safe alternative to C-section for delivery of the infant.     

Dantrolene in pregnancy: lack of adverse effects on the fetus and newborn infant

Twenty malignant hyperthermia-susceptible pregnant patients were given dantrolene sodium orally for 5 days before delivery and 3 days after delivery. When cesarean section was necessary, triggering agents were avoided. No patient had a malignant hyperthermia reaction. No adverse effect of dantrolene sodium was detected by extensive testing of the fetus and neonate. The maternal predelivery dantrolene level was correlated with the noenatal cord blood dantrolene level (r = 0.837). The mean maternal predelivery dantrolene level was 0.99 +/- 0.5 microgram/ml, and the mean neonatal cord blood dantrolene level 0.68 +/- 0.3 microgram/ml. The time from the last dose of dantrolene to delivery was correlated with both the maternal dantrolene level and the neonatal cord blood level (r = 0.65). The half-life of dantrolene in the neonatal circulation was 20 hours. The controversy of oral dantrolene prophylaxis and the implications of this study with regard to further investigation are discussed.     

Uterine tocolysis at cesarean breech delivery with epidural anesthesia

OBJECTIVE: To assess the safety and efficacy of ritodrine and nitroglycerin for uterine relaxation during cesarean section with a breech-presenting fetus, performed under nongeneral anesthesia. STUDY DESIGN: A retrospective review of all breech singletons delivered by cesarean section under epidural anaesthesia in a two-year period. The study groups consisted of those who received ritodrine and those who received nitroglycerin. A group who received no relaxant served as a comparison group. The interval from uterine incision to delivery was recorded, and comparisons for potential complications of the medications included maternal changes in pulse and blood pressure, blood loss, and changes in hemoglobin and hematocrit. Fetal outcomes that were evaluated included five-minute Apgar score, cord pH and any recorded birth trauma. Statistical significance was set at P = .05. The Student t test, Yates's correlation for chi 2, Fisher's exact test and ANOVA were used as appropriate. RESULTS: The three groups had similar demographic characteristics. There was no significant difference in the uterine incision to delivery interval between the groups. In three cases the uterine incision to delivery interval was prolonged (> 5 minutes) in the nitroglycerin group, six cases in the ritodrine group and three in the comparison group (P = .002). There was no case of serious maternal morbidity or mortality, and no patient required a blood transfusion. The three groups had similar estimated blood loss, changes in maternal heart rate and systolic blood pressure intraoperatively and fall in hemoglobin and hematocrit 24 hours postoperatively. Neonatal outcome was similar among the three groups, and there was no case of neonatal birth trauma or intrapartum death. Cord blood analysis was similar in the three groups. One of the seven infants weighing < 1,500 g died within one hour of birth. CONCLUSION: Ritodrine and nitroglycerine are safe agents for use at cesarean breech delivery with epidural anesthesia and may be considered for uterine relaxation when a traumatic delivery is anticipated or encountered. Our results do not support the use of these tocolytics for "routine" cesarean breech delivery.     

Ultrasonographic assessment of fetal and neonatal spleen.

To assess the growth and function of the fetal spleen, ultrasonographic examinations were performed on 229 normal fetuses, ranging from 20 to 41 weeks, menstrual age. Curvilinear relationships were found between the menstrual age and splenic length (R2 = 92.7%), circumference (R2 = 93.9%), and area (R2 = 95.2%). A normal range of splenic length, circumference, and area measurements for estimating the growth of the fetal spleen during normal pregnancy was generated. Splenic parameter values just after delivery were significantly lower than those measured within 7 days before delivery, and returned to former sizes 24 hours later, in both vaginal delivery and cesarean section groups. Splenic parameter values in the vaginal delivery group were also significantly lower than those in the cesarean section group, just after delivery. Moreover, neonatal splenic length showed negative correlations with lactate dehydrogenase (p < 0.001) and glutamic oxaloacetic transaminase (p < 0.05) in the umbilical venous blood, respectively. These results provide a foundation for the evaluation of fetal splenic growth and function during pregnancy and the early neonatal period.     

正常妊娠及合并胎儿窘迫孕妇与新生儿不同分娩方式时血气及酸碱平衡变化

对４６例正常妊娠妇女（对照组）和４１例合并胎儿窘迫的足月妊娠妇女（窘迫组），于分娩时进行足背动脉和新生儿脐静脉、脐动脉血气分析；并将阴道分娩和剖宫产时酸碱平衡变化作了比较。结果：两组产妇动脉血除剩余碱（ＢＥ）偏低（＜－３ｍｍｏｌ／Ｌ）外，其余各值均在正常范围内，两组间各项指标比较，差异无显著性；两组脐静脉血气各项指标差异也无显著性；与对照组比较，窘迫组脐动脉血ｐＨ值、氧分压（ＰＯ＿２）、血氧饱和度（Ｏ＿２Ｓａｔ）均明显降低，二氧化碳分压（ＰＣＯ＿２）明显升高（Ｐ＜００５）。与剖宫产比较，两组阴道分娩产妇均显示有轻度代谢性酸中毒并轻度低氧血症，窘迫组胎儿酸中毒现象更为明显，新生儿出生时Ａｐｇａｒ评分≤７分的发生率也较高。提示：缩短产程对改善胎儿窘迫有重要意义。