Proposed cutoff for fetal scalp blood lactate in intrapartum fetal surveillance based on neonatal outcomes: a large prospective observational study.

OBJECTIVE: Determination of lactate in fetal scalp blood (FBS) during labour has been recognised since the 1970s. The internationally accepted cutoff of >4.8 mmol/l indicating fetal acidosis is exclusive for the point-of-care device (POC) LactatePro™, which is no longer in production. The aim of this study was to establish a new cutoff for scalp lactate based on neonatal outcomes with the use of the StatstripLactate® /StatstripXpress® Lactate system, the only POC designed for hospital use. DESIGN: Observational study. SETTING: January 2016 to March 2020 labouring women with indication for FBS were prospectively included from seven Swedish and one Australian delivery unit. POPULATION: Inclusion criteria: singleton pregnancy, vertex presentation, ≥35+0 weeks of gestation. METHOD: Based on the optimal correlation between FBS lactate and cord pH/lactate, only cases with ≤25 minutes from FBS to delivery were included in the final calculations. MAIN OUTCOME MEASURES: Metabolic acidosis in cord blood defined as pH <7.05 plus BDecf >10 mmol/l and/or lactate >10 mmol/l. RESULTS: A total of 3334 women were enrolled of whom 799 were delivered within 25 minutes. The areas under the receiver operating characteristics curves (AUC) and corresponding optimal cutoff values were as follows; metabolic acidosis AUC 0.87 (95% CI 0.77-0.97), cutoff 5.7 mmol/l; pH <7.0 AUC 0.83 (95% CI 0.68-0.97), cutoff 4.6 mmol/l; pH <7.05 plus BDecf ≥12 mmol/l AUC 0.97 (95% CI 0.92-1), cutoff 5.8 mmol/l; Apgar score <7 at 5 minutes AUC 0.74 (95% CI 0.63-0.86), cutoff 5.2 mmol/l; and pH <7.10 plus composite neonatal outcome AUC 0.76 (95% CI 0.67-0.85), cutoff 4.8 mmol/l. CONCLUSION: A scalp lactate level <5.2 mmol/l using the StatstripLactate® /StatstripXpress® system will safely rule out fetal metabolic acidosis. TWEETABLE ABSTRACT: Scalp blood lactate <5.2 mmol/l using the StatstripLactate® /StatstripXpress system has an excellent ability to rule out fetal acidosis.

Use of Lactate ProTM2 for measurement of fetal scalp blood lactate during labor - proposing new cutoffs for normality, preacidemia and acidemia: a cross-sectional study.

OBJECTIVE: Measurement of fetal scalp blood lactate is a supplementary tool to cardiotocography in the case of a non-reassuring tracing. Several hand-held lactate meters have been launched, all with differentials in absolute values. Therefore, the reference intervals must be calculated for each device. The internationally accepted reference interval is based on measurement with Lactate ProTM with recently got out of production. The aim of this study was to propose cutoffs for normality, preacidemia, and acidemia in fetal scalp blood for Lactate ProTM2 based on the comparison of lactate values measured with Lactate ProTM and Lactate ProTM2. DESIGN: Seven hundred one fetal scalp blood samples were analyzed simultaneously. The conversion equations were retrieved from the linear regression model. On the basis of the cutoffs for Lactate ProTM cutoffs for Lactate ProTM2 were calculated. RESULTS: The conversion equations obtained were Lactate ProTM = -0.02 + 0.68 × Lactate ProTM2 (SD: -0.09-0.07 × Lactate ProTM2) and Lactate proTM2 (LP2) = 0.03 + 1.48 × Lactate ProTM (SD: 0.16 + 0.17 × Lactate ProTM). The correlation to umbilical arterial pH was identical for the two devices (r = -0.18), whereas the correlation to umbilical arterial lactate was better for Lactate ProTM than for Lactate ProTM2 (r = 0.38, respectively, r = 0.33). The correlation to umbilical arterial lactate was dependent on time from sampling to delivery. CONCLUSION: Proposed reference values for Lactate ProTM2: scalp lactate <6.3 mmol/L = normal, no indication for intervention; 6.3-7.1 mmol/L = preacidemia, repeated testing has to be considered; > 7.1 mmol/L = acidemia, expedite delivery.

Hidden acidosis: an explanation of acid-base and lactate changes occurring in umbilical cord blood after delayed sampling.

OBJECTIVE: To explore the 'hidden acidosis' phenomenon, in which there is a washout of acid metabolites from peripheral tissues in both vaginal and abdominal deliveries, by investigating temporal umbilical cord blood acid-base and lactate changes after delayed blood sampling. DESIGN: Prospective comparative study. SETTING: University hospital. SAMPLE: Umbilical cord blood from 124 newborns. METHODS: Arterial and venous cord blood was sampled immediately after birth (T0), and at 45 seconds (T45), from unclamped cords with intact pulsations taken from 66 neonates born vaginally and 58 neonates born via planned caesarean section at 36-42 weeks of gestation. Non-parametric tests were used for statistical comparisons, with P < 0.05 considered significant. MAIN OUTCOME MEASURES: Temporal changes (T0-T45) in umbilical cord blood pH, the partial pressure of CO2 (PCO2) and O2 (PO2), and in the concentrations of lactate, haematocrit (Hct), and haemoglobin (Hb). RESULTS: In both groups all arterial parameters, except for PCO2 in the group delivered by caesarean section, changed significantly (pH decreased and the other variables increased). There were corresponding changes in venous acid-base parameters. When temporal arterial changes were compared between the two groups, the decrease in pH and increase in PCO2 were more pronounced in the group delivered vaginally. Neonates born vaginally had significantly lower pH and higher lactate, Hct, and Hb concentrations at T0 and T45 in both the artery and the vein. At T45, arterial PCO2 and PO2 levels in the group delivered vaginally were also significantly higher. CONCLUSIONS: Delayed umbilical cord sampling affected the acid-base balance and haematological parameters after both vaginal and caesarean deliveries, although the effect was more marked in the group delivered vaginally. The hidden acidosis phenomenon explains this change towards acidaemia and lactaemia. Arterial haemoconcentration was not the explanation of the acid-base drift.

Delayed umbilical cord clamping at birth has effects on arterial and venous blood gases and lactate concentrations.

OBJECTIVE: To estimate the influence of delayed umbilical cord clamping at birth on arterial and venous umbilical cord blood gases, bicarbonate (HCO3-), base excess (BE) and lactate in vigorous newborns. SETTING: University hospital. DESIGN: Prospective observational. SAMPLE: Vaginally delivered term newborns. MATERIAL AND METHODS: Umbilical cord arterial and venous blood was sampled repeatedly every 45 seconds (T(0)= time zero; T(45)= 45 seconds, T(90)= 90 seconds) until the cord pulsations spontaneously ceased in 66 vigorous singletons with cephalic vaginal delivery at 36-42 weeks. Longitudinal comparisons were performed with the Wilcoxon signed-ranks matched pairs test. Mixed effect models were used to describe the shape of the regression curves. MAIN OUTCOME MEASURES: Longitudinal changes of umbilical cord blood gases and lactate. RESULTS: In arterial cord blood, there were significant decreases of pH (7.24-7.21), HCO3- (18.9-18.1 mmol/l) and BE (-4.85 to -6.14 mmol/l), and significant increases of PaCO(2) (7.64-8.07 kPa), PO(2) (2.30-2.74 kPa) and lactate (5.3-5.9 mmol/l) from T(0) to T(90), with the most pronounced changes at T(0)-T(45). Similar changes occurred in venous blood pH (7.32-7.31), HCO3- (19.54-19.33 mmol/l), BE (-4.93 to -5.19 mmol/l), PaCO(2) (5.69-5.81 kPa) and lactate (5.0-5.3 mmol/l), although the changes were smaller and most pronounced at T(45)-T(90). No significant changes were observed in venous PO(2). CONCLUSION: Persistent cord pulsations and delayed cord clamping at birth result in significantly different measured values of cord blood acid-base parameters.

Lactate concentration in umbilical cord blood is gestational age-dependent: a population-based study of 17 867 newborns.

OBJECTIVE: To study the influence of gestational age on lactate concentration in arterial and venous umbilical cord blood at birth and to define gestational age-specific reference values for lactate in vigorous newborns. DESIGN: Population-based comparative. SETTING: University hospitals. SAMPLE: Vigorous newborns with validated umbilical cord blood samples. MATERIAL AND METHODS: From 2000 to 2004, routine cord blood gases, lactate and obstetric data from two university hospitals were available for 17 867 newborns from gestational week 24 to 43. After validation of blood samples and inclusion only of singleton pregnancies aimed for vaginal delivery, 10 700 women remained. Among those, reference values were defined in 10 169 vigorous newborns, that is in newborns with a 5-minute Apgar score corresponding to the gestational age-specific median value minus 1 point score, or better. MAIN OUTCOME MEASURES: Cord lactate concentration relative to gestational age. RESULTS: The arterial and venous lactate concentrations increased monotonously with gestational age from 34 weeks. Considerable differences were found between mean and median values, but after logarithmic transformation the log-lactate values were normally distributed. Simple linear regression analysis showed a significant association between the log-lactate values and gestational age (P < 10(-6), R(2)= 0.024). Reference curves were constructed after anti-logarithmic transformation. Both the gestational age and the time of the second stage of labour influenced, independently of each other, the lactate concentrations. CONCLUSIONS: Lactate concentrations in arterial and venous umbilical cord blood are increasing significantly with advancing gestational age.

[Ga18(SitBu3)8] and [Ga22(SitBu3)8]--syntheses and structural characterization of novel gallium cluster compounds.

The novel neutral gallium cluster compounds [Ga18R*8] (1) and [Ga22R*8] (2) are obtained by warming up a metastable solution of gallium(I) bromide in THF/C6H5CH3 after addition of equimolar amounts of supersilyl sodium NaR* from -78 degrees C to room temperature (R* = SitBu3 = supersilyl). From X-ray structure analyses, the observed arrangements of the 18 and 22 Ga atoms in 1 and 2, respectively, are comparable with an 18 atom section of the beta-Ga modification, or show at least some kind of relationship to a 22 atom section of the Ga-III modification. This allows a description of both the clusters as metalloid. The topology of the atoms in 2 is also well explained by the Wade-Mingos rules as an eightfold capped closo-Ga14 cluster, whereby the Ga atoms of Ga14 occupy the center and the corners of a cuboctahedron with one Ga3 face replaced by a Ga4 face. Some concepts are presented about the formation mechanism, the cluster growth, and the metalloid character of the two Ga cluster compounds.

Hexasupersilyloctaindane (tBu(3)Si)(6)In(8)- A Compound with a Novel In(8) Cluster Framework.

A doubly capped In(6) octahedron characterizes the structure of the dark green octaindane (tBu(3)Si)(6)In(8) (see picture), which is obtained from (C(5)Me(5))In and tBu(3)SiNa in pentane at -78 degrees C. In1/In1' are the capping atoms, and In2/In2' form the apexes of the stretched In(6) octahedron. Thus, in agreement with the results of ab initio calculations, the compound can be classified as a hypoprecloso-indane.

Hexasupersilyl-triprismo-hexastannane (tBu3 Si)6 Sn6 -The First Molecular Tin Compound Containing a Sn6 Prism.

Dark violet hexastannane (tBu3 Si)6 Sn6 displays a new framework motif for molecular tin compounds, in which six Sn atoms are located at the corners of a trigonal prism. The compound can be synthesized according to Equation (a). R*=SitBu3 .

Circulating concentrations of placenta protein 14 during the natural menstrual cycle in women significantly reflect endometrial receptivity to implantation and pregnancy during successive assisted reproduction cycles.

Placenta protein 14 (PP14), which is the most abundant product of the secretory endometrium, has been proposed as the best biochemical marker of endometrial function in women. In this study, 19 normogonadotrophic women of infertile couples were monitored with serial measurements of concentrations of PP14, gonadotrophins and sex steroids and ultrasound scanning of endometrial thickness throughout three consecutive cycles. The first two of these were natural, unstimulated cycles (cycles 1 and 2), while ovarian stimulation with clomiphene and human menopausal gonadotrophin combined with assisted reproduction (intrauterine insemination in four cases and in-vitro fertilization in 15) was performed in the third cycle (cycle 3). A newly developed enzyme-linked immunosorbent assay was used to measure serum PP14 concentrations. In cycle 3, seven women became pregnant (group A) and 12 did not (group B). Circulating concentrations of PP14 were significantly lower in group A than in group B throughout all three cycles and in all cycle phases with exception of the late luteal phase of cycle 3, during which PP14 concentrations in group A were significantly higher than in group B. Statistical analyses showed no significant correlations between serum concentrations of PP14 and follicle stimulating hormone, luteinizing hormone and progesterone, and endometrial thickness. By contrast, serum oestradiol concentrations during the pre-ovulatory phase were significantly correlated with PP14 concentrations during the mid-luteal phase of the cycle. It is concluded that circulating PP14 is a most reliable biochemical marker of endometrial function in women and that relatively low concentrations in serum during the natural, unstimulated cycle are significantly correlated to implantation and pregnancy during successive assisted reproduction cycles. Measurement of PP14 in serum may thus be useful as a method of screening endometrial function in women, before commencing troublesome and costly treatment for infertility. However, further studies in a much larger number of women are needed to confirm this observation and to elucidate the as yet undefined physiological functions of PP14 in women.