Fetal and maternal transcutaneous PCO2 levels during labour and the influence of epidural analgesia.

The Departments of Obstetrics and Gynaecology of the Hvidovre University of Copenhagen and the Free University of Amsterdam collaborated in a study on the relationship of maternal and fetal acid-base state in the intrapartum period. Transcutaneous PCO2 levels of mother (tcPCO2m) and fetus (tcPCO2f) were continuously recorded in 52 patients during labour. TcPCO2f and tcPCO2m correlated significantly (r = 0.42, P < 0.002). During the first stage of labour, a rather stable level was found for tcPCO2f (7.7 +/- 1.6 kPa) and tcPCO2m (4.4 +/- 0.8 kPa). TcPCO2m decreased significantly to 3.8 +/- 0.7 kPa (P < 0.01) in the hour before full cervical dilatation, probably due to maternal hyperventilation as a reaction to painful uterine contractions. TcPCO2f likewise showed a tendency to a decrease to a mean value of 7.4 +/- 1.5 kPa. In eight cases epidural analgesia was applied because of painful uterine contractions. Prior to the epidural analgesia, tcPCO2m (3.8 +/- 0.8 kPa) and tcPCO2f (6.7 +/- 1.7 KPa) were significantly lower in this subgroup compared to the total population. After pain relief by application of epidural analgesia, tcPCO2m and tcPCO2f returned to the population mean.

Induction of labour by balloon catheter with extra-amniotic saline infusion (BCEAS): a randomised comparison with PGE2 vaginal pessaries.

OBJECTIVE: A new method for induction of labour--balloon catheter with extra-amniotic saline infusion (BCEAS)--is evaluated in randomised comparison with prostaglandin E2 (PGE2) in vaginal pessaries. STUDY GROUP: One-hundred and nine pregnant women with unfavourable cervices. MAJOR OUTCOME MEASURES: The efficiency of inducing vaginal delivery and the level of 'disadvantages following induction of labour' (DisFIL scorings). RESULTS: Overall, BCEAS was less efficient inducing vaginal delivery than vaginal PGE2 (P < 0.01) because of a significant difference among parous women (P < 0.01). In the (larger) primiparous women group, and particularly in the subgroup of these having very low pelvic scores (Lange score, < or = 3), the efficiencies of the two methods were equal (P = 0.06) and P = 0.55, respectively). The levels of DisFIL scorings were not significantly different. However, higher rates of caesarean section followed BCEAS than PGE2 (29% and 10%, respectively; P < 0.05). Serious infectious complications were not recorded following BCEAS. No difference was apparent in the status of the neonates (judging from Apgar scores and umbilical artery pH and SBE). The women, delivering vaginally, commented the two methods equally favourably. CONCLUSION: BCEAS was less efficacious than vaginal PGE2 pessaries, though among primiparous women, especially those with very unfavourable cervices, the difference was not significant. Further refinements of the method are suggested.

Prediction of mode of delivery and 'DisFIL score' following induction of labor by local PGE2.

The objective of the study was to evaluate pre-induction risk factors for (i) assisted vaginal delivery (forceps or vacuum extraction), (ii) caesarean section, (iii) failed induction followed by caesarean section, and from these to evaluate a score of the 'Disadvantages Following Induction of Labour' (the DisFIL score). The study was a case-control study applied on a prospective cohort of 336 pregnant women induced by local PGE2. Assisted vaginal delivery was associated with primiparity (OR (odds ratio) = 10.7; CI, 3.6-32.0) and higher pelvic scores (Bishop score: OR = 1.9; CI, 1.4-2.6). Caesarean section was related to higher maternal age (P < 0.001) and lower pelvic scores (Bishop score: OR = 0.7; CI, 0.5-1.0, P < 0.05). When performed because of fetal distress, assisted vaginal delivery and caesarean section were both associated with lower fetal weights (P < 0.05). Failed induction followed by caesarean section was related to primiparity (P < 0.0001, Fisher's test) and lower pelvic scores (Bishop score: OR = 0.6; CI, 0.4-0.9). A higher 'DisFIL score' was associated with primiparity (OR = 4.7; CI, 2.8-8.0), higher maternal age (P < 0.01), lower pelvic scores (P < 0.01, chi 2 test) and PGE2 in intracervical gel rather than in vaginal pessaries (OR = 2.1; CI, 1.4-3.2). It is concluded that the major predictors of 'Disadvantages Following Induction of Labor' by local PGE2 are primiparity, high maternal age, low pelvic scores and the method of.

Fetal transcutaneous PCO2 measurements during labour.

The departments of Obstetrics and Gynaecology of the Universities of Bonn and Copenhagen and the Free University of Amsterdam cooperated in the European Community Concerted Action Project 'New methods for Perinatal Surveillance'. In 95 patients fetal transcutaneous PCO2 (tcPCO2) recording (measuring temperature 41 degrees C) during labour was evaluated regarding its clinical applicability. During the first stage of labour fetal tcPCO2 was rather stable at a level of 7.3 +/- 1.4 kPa. In the second stage there were marked differences between the three subpopulations. In the first stage of labour the correlation between tcPCO2 and PCO2 in fetal blood samples was 0.38 (P = 0.02) and in the second stage -0.20 (P = 0.36). The correlation of fetal tcPCO2 with umbilical artery PCO2 was 0.30 (P = 0.01) and with pH -0.30 (P = 0.01). Using a fetal tcPCO2 level of 8.0 kPa as a cut-off point to predict an umbilical artery pH less then 7.20, sensitivity was 88%, specificity 65%, positive predictive value 29% and negative predictive value 97%. The likelihood ratio of a positive test was 2.47 and of a negative test 0.13. It is concluded that fetal tcPCO2 possibly can be an additional tool to exclude fetal acidosis. In case of values above 8.0 kPa further evaluation of the fetal acid-base balance is indicated.

[T/QRS-ratio and cardiotocographic changes in the second stage of labor--related to fetal condition at delivery]. / T/QRS-ratio og kardiotokografiforandringer i andet stadium af fødslen--relateret til fostrets tilstand ved fødslen.

The T/QRS ratio of the foetal electrocardiogram (ECG) was recorded from 92 women in labour. Recordings to within 30 min of delivery from 55 women were available for analysis. There was a weak but statistically significant correlation between increasing mean T/QRS ratio and increasing pH/standard base excess (SBE) in the umbilical artery of the 55 foetuses (Spearman, respectively r = 0.28, p = 0.04 and r = 0.29, p = 0.04); the corresponding numbers for the subgroup of 22 where the cardiotocogram was classified as normal being respectively r = 0.51, p = 0.02 and r = 0.61, p = 0.003. The mean T/QRS ratio of foetuses born with an umbilical artery pH of > 7.15 was 0.12 (range -0.05-0.32). There was no significant difference in mean T/QRS ratio between foetuses born with an umbilical artery pH < 7.16 (n = 10) and those born with a pH > 7.15. No trend in T/QRS ratio was found as labour progressed. There were only three cases of metabolic acidose (SBE = -10.3 to -10.6 mmol/l and pH = 7.09-7.14. In two of the cases the CTG was abnormal and in one case intermediate; mean T/QRS ratio was normal in all three cases with metabolic acidosis. Abnormal CTG was able to predict an umbilical artery pH < 7.15 with a sensitivity of 67% and a positive predictive value of 27%. T/QRS ratio (T/QRS = -0.05-0.25: "normal") was not able to predict a low pH. The chance of finding significant changes in T/QRS ratio was limited by the small number of foetuses with clinically significant acidosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Predictive value of pelvic scores for induction of labor by local PGE2.

The predictive value of pelvic scores, parity, age and gestational age for induction of labor by local prostaglandin-E2 (PGE2) was examined in 336 women attempting induction of labor by intracervical or vaginal PGE2. The patient characteristics were correlated to: (1) vaginal delivery within 48 h, (2) the period from induction to onset of labor (latency period), and (3) the duration of labor. The Bishop score (P < 0.01) and even more the Lange score (P < 0.0001) were significantly inversely correlated to both latency period and induction-delivery period. This was caused by cervical dilatation (P < 0.001), fetal station (P < 0.05) and cervical length (P < 0.05), whereas position and consistency of the cervix were of no importance. All three periods studied were significantly (P < 0.0001) shorter in parous women. In primiparous women, gestational age was of no importance for the latency period; however, higher gestational age was associated with longer labor (P < 0.001). We conclude that the predictive value of pelvic scores on induction hardly differs using local PGE2 compared to conventional methods; furthermore, the Bishop score should be substituted, disregarding position and consistency of the cervix, but putting more weight to cervical dilatation. A new pelvic score is proposed.

Induction of labor by prostaglandin E2: intracervical gel or vaginal pessaries?

To investigate the best route of prostaglandin medication for induction of labor, 125 pregnant women with unfavorable cervices (Bishop scores less than or equal to 6) were randomized to induction of labor with either PGE2 (0.5 mg) in a viscous intracervical gel once daily or PGE2 pessaries (2.5 mg) 1-2 a day. As estimated by life table analysis, the pessaries were significantly more effective inducing vaginal delivery compared to intracervical gel (24 h: P less than 0.025, 48 h: P less than 0.01, logrank test) and vaginal delivery was obtained within 24 h/48 h in 50%/72% of the women in the pessary group and in 29%/55% of the women in the intracervical group. Cervical ripening was found within 3 h (P less than 0.001) and in the subsequent 3 to 24 h period (P less than 0.005) after both treatments, no difference being found between the groups. The pessaries were much more effective inducing regular contractions compared to the intracervical gel (P less than 0.005, logrank test), so the latter seems preferable if cervical ripening rather than induction is intended. No difference was found analyzing the active labor period. No difference was found in methods of delivery, neonatal parameters (Apgar scores, umbilical artery blood pH and standard base excess), and the patients' attitude towards both methods of induction were equally favorable.

The current status of intrapartum continuous fetal tissue pH measurements.

Continuous tissue pH monitoring during labor has now been possible for 15 years. Tissue pH is measured in the intercellular fluid, and the value differs in some cases from the blood pH value because of local capillary flow and local metabolism. The fetal scalp seems to be an area where tissue pH and capillary blood pH values are very close, but in acute acidosis there may be a time lag of 10-15 min before tissue pH is equilibrated. Normal values of scalp tissue pH are 7.38 in early labor declining by 0.016 per hour during the first stage of labor and by 0.12 per hour during the second stage of labor. Tissue pH values below 7.15 are defined as pathological. The correlation coefficient to umbilical artery blood pH (0.71), success rate (67%) and electrode drift (below 0.04) from the largest study of tissue pH monitoring using glass pH electrodes (n = 337) are described.

[Cardiotocographic monitoring of deliveries. A prospective comparative study of 2 types of electrodes]. / Kardiotokografisk fødselsovervågning. En prospektiv sammenlignende undersøgelse af to elektrodetyper.

The number of electrodes employed, the frequency of reapplication, the technical quality of monitoring and the complications of use of spiral electrodes and Copeland electrodes for cardiotocographic monitoring of deliveries are assessed in a prospective randomized investigation. The number of electrodes employed and the frequency of reapplications were significantly lower employing Copeland electrodes. Similarly, the electrode signal was significantly better as assessed by the percentage of the duration of monitoring in which the cardiotocogram did not register during the second stage of labour on account of poor electrode signals. No differences were found in the frequencies of complications or subjective discomfort in the mother on employing the two types of electrodes.

Normal range of fetal transcutaneous carbon dioxide tension during labour.

Fetal transcutaneous carbon dioxide tension (tc-PCO2) was monitored during 122 deliveries, using an electrode temperature of 44 degrees C in 80 cases and of 41 degrees C in 42 cases. Significant correlations between tc-PCO2 and umbilical artery blood PCO2 were found using both electrode temperatures, but the regression lines indicated a larger and more inconstant CO2-contribution from skin metabolism when the low electrode temperature was used. Normal range of tc-PCO2 was calculated at 41 degrees C and 44 degrees C electrode temperatures. Mean values of fetal tc-PCO2 were found to increase during normal labour, and especially in fetuses developing acidosis, but only four of six infants born with acidaemia had tc-PCO2 values exceeding the normal range.

Computer assessment of the intrapartum cardiotocogram. I. Methods of data reduction and diagnostic procedure.

To solve the problem of low predictive values in the visual assessment of the CTG, several computer programs have been designed. Only a few of those programs describe the CTG automatically and thus consistently. The aim of this study was to construct a diagnostic procedure for computer-aided automatic assessment of the CTG. A computer program quantified 17 variables of the CTG. Within a window of user-defined length, a second program calculated the number of measurements, the mean, the trend, and the coefficient of variation of each of the 17 variables, and produced a total of 56 distinct subvariables. A discriminant procedure was set up which could use any number and combination of the 56 subvariables to calculate the probability of a CTG derived from a compromised infant. The diagnostic procedure was optimized by "direct forward search" for the combination of subvariables discriminating best between normal and compromised infants. Using the last half hour of the first stage of labor, 50 CTGs entered the optimizing procedure. A combination of nine subvariables was found. In a separate paper its performance is compared with that of clinicians.

Computer assessment of the intrapartum cardiotocogram. II. The value of compared with visual assessment.

The chief aim of our work has been to create a computer Cardiotocographic Assessment System (CAS) and thus eliminate the intra- and inter-observer variability of the visual assessment of the cardiotocogram (CTG), and to improve the assessment of the CTGs to the standard of the most experienced obstetricians. The purpose of this paper is to present the accuracy of the prediction of fetal outcome obtained by the CAS and to compare it with 4 experienced obstetricians' accuracy. Fifty CTGs from the last 30 min. of labor were assessed as normal or pathological by the computer and by the obstetricians. The condition of the newborn was evaluated from the one-minute Apgar score, the umbilical artery pH and standard base excess, and the need for resuscitation. The accuracy of the CAS was significantly better than the accuracy of the obstetrician obtaining the best result. We conclude that the development of a computer-aided cardiotocographic assessment system is worthwhile.