Jacques F. Roux

Total lipids and the lecithin-sphingomyelin ratio of amniotic fluid: An antenatal test of lung immaturity?☆

Abstract The total lipid concentration and the lecithin-sphingomyelin ratio (L/S) were measured in the amniotic fluid from human gestations within 24 hours of delivery. The data show that the L/S determined by two-dimensional thin-layer chromatography and the concentration of total lipids are each reliable indicators of gestational age but not of lung immaturity.

Further observations on the determination of gestational age by amniotic fluid analysis

The concentration of amniotic fluid total lecithin, creatinine, lipids, and the ratio of total lecithin to sphingomyelin (L/S) are each reliable indices of fetal age. When the L/S ratio indicates immaturity, chances that the newborn infant will develop respiratory distress are directly related to the incidence of this syndrome in a random population of premature fetuses of similar gestational age. Acetone precipitation of lecithin and sphingomyelin before visual or chemical quantitation is not required. No significant decrease in amniotic fluid sphingomyelin concentration can be measured between the thirty-second and fortieth weeks of gestation. Fat cells are found mostly in the fetal skin and vernix. Lecithin and sphingomyelin are detected in the amniotic fluid and membrane as well as in the aspirates of the pharvnx.

Fatty acid composition and concentration of lecithin in the acetone fraction of amniotic fluid phospholipids

Abstract The concentration and fatty acid composition of acetone- and non-acetone-precipitated lecithin, the L/S ratio, and the concentration of phosphate in lipids were measured in aliquots of amniotic fluid obtained at different periods of gestation. Irrespective of the technique of precipitation of the phospholipids, no significant differences in fatty acid composition or concentration of lecithin can be detected within the same gestational age except for the presence of C 12 and C 20 fatty acids in the acetone-soluble phospholipids. Increase in C 16:0 fatty acid concentration and composition can be demonstrated with fetal age in the acetone- and non-acetone-precipitated lecithin. The L/S ratios measured in both preparations differ numerically, but are linearly related. The L/S ratio can be evaluated visually as well as by densitometry. The concentration of phosphate in total amniotic fluid lipid increases with gestational age, though the S.D. is large. These results demonstrate that the acetone precipitation of phospholipids with densitometry measurement of the L/S ratio offers no advantages over the visual determination of the ratio on total amniotic phospholipids. It also indicates that the acetone precipitation of lecithin is not specific for lung surfactant, at least in amniotic fluid. There is no evidence that lecithin synthesized in the second trimester contains a high percentage of C 14 chain length fatty acids, as would be expected if the methylation pathway was predominant at this stage of gestation.

In vitro metabolism of palmitic acid and glucose in the developing tissue of the rhesus monkey

Fetal, newborn, and adult tissues of rhesus monkeys metabolize glucose-U- 14 C and palmitate-1- 14 C to lipids and 14 CO 2 in vitro. During growth and development, differences in substrate utilization are detected. In the lung, phospholipid synthesis with the use of either substrate increases as development proceeds. In the brain, lipid synthesis diminishes after birth, though glucose utilization and 14 CO 2 production from glucose-U- 14 C increase. The metabolism of liver lipids varies with age, the term fetus and newborn infant converting less palmitate to lipids than the young fetus or the adult animal. Most of the radioactivity of palmitate is found in the 16 C fatty acid fraction of the various lipids. In the newborn infant, the catabolism of glucose-U- 14 C or palmitate-1- 14 C increases in the brain and lung while palmitate curtails glucose utilization in these tissues. Since palmitate has been shown to cross the rhesus monkey placenta in vitro and in vivo, to curtail glucose utilization, and to be incorporated into fetal lipids, the present data indicate that fatty acids of either maternal or fetal origin can, along with glucose, be utilized for the formation of fetal lipids. In fetal tissues, the conversion of palmitate to carbon dioxide is small. Therefore, a limited but steady flow of fatty acids of maternal origin may account for a large proportion of total fetal tissue lipid deposition. The data indicate that, while glucose metabolism is essential to the primate fetus, lipid synthesis from fatty acids may be more important than it is presently considered.

Amniotic fluid beta-2 microglobulin concentration—an index of gestational age

Abstract Beta-2 microglobulin concentrations were measured in amniotic fluid obtained from 20 women at various stages of gestation. The concentrations averaged 6.3 μg per milliliter (range 5 to 10) between the tenth and thirty-sixth weeks and 0.87 μg per milliliter (range 0.2 to 1.3) after 36 weeks. This rapid third-trimester decrease in amniotic fluid concentration suggests that a major fetal pathway for metabolism of this protein becomes functional late in the course of gestation. From what is known of beta-2 microglobulin metabolism, this most likely relates to renal tubular function and suggests that this test may have significance in determining fetal age.

A wireless radiotelemetry system for monitoring fetal heart rate and intrauterine pressure during labor and delivery.

A wireless radio telemetry system for the continuous monitoring of fetal heart rate and intrauterine pressure during labor has been designed, constructed, and clinically tested. The system is based upon a miniature or microminiature battery powered two-channel radio transmitter which can be located near or within the vagina respectively. The range of transmission is 10 to 20 m. A noise reducing cardiotachometer is incorporated in the system to reduce artifact by imposing amplitude, duration, and interval criteria to recognize fetal beats. A clinical evaluation of the monitor on 10 patients for an average time of 215 min has shown it to be equivalent to conventional wire monitoring techniques.

Validity of intrauterine pressure measurements with transcervical intra-amniotic catheters and an intra-amniotic miniature pressure transducer during labor.

The accuracy of transvaginal intrauterine pressure measurements was determined in 21 subjects in labor, 12 of which were monitored with two transcervical intrauterine catheters and one miniature intrauterine pressure transducer, and 9 subjects of which were monitored with a double lumen transcervical catheter. Statistical analysis of variance of data from the first group showed significant sensor variations. Pressure amplitude ratios between different sensors for the same contraction were calculated for all contractions and were found to vary with a coefficient of variation of greater than 23%. This value was reduced to less than one half when a double lumen catheter with adjacent tips was used or only smooth bell-shaped contractions were considered. The internal transducer was shown to give equivalent data to that obtained from the catheter and external pressure transducer combinations. It is concluded that no single uterine pressure observation is an accurate reflection of uterine pressure during labor.

Assessment of fetal maturation by the foam test

Abstract The foam test, performed in 66 high-risk pregnancies, has been shown to diagnose fetal maturity reliably only when it was “positive.” When the test was negative, the fetus, in 73.3 per cent of the cases, was premature, and the incidence of hyaline membrane disease was similar to that observed in premature fetuses of similar gestational age. An intermediate result in the test detected fetal maturity in 80 per cent of the cases and was not associated with hyaline membrane disease. Although a positive foam test correlated significantly with the concentration of amniotic fluid lecithin, tests with positive, intermediate, and negative results were found at lecithin concentrations lower than 180 μg per cent. This observation opens to question the validity of the test as an indirect measurement of lung surfactant material. The foam test, being economical, reliable, and fast, should replace the lecithin-sphingomyelin ratio test.

Computer diagnosis of labor progression

Abnormal labor has been suspected of being inherently delectorious to the fetus. In order to explore this problem, clinical factors, labor progress, and fetal monitoring parameters were compared in matched groups of high-risk patients whose fetuses were in theoccipitoposterior (0P) and occipitoanterior postions. The OP group showed significant excesses of dysfunctional labor aptterns, uterine contraction pattern abnormalities, and late and variabl fetal heart rate decelerations not accounted for by theuse of oxytocin or the presence of cord problems. In OP labor, lower Apgar scores were associated withasignificant excess of preceding fetal heart rate decelerations independant of operative delivery. This study suggests that neonatal depression in OP laboris related to intrapartum factors preceding delivery and provides direct support for theconcept that abnormal labor may adversely affect the fetus. The OP position is an indication for close fetomaternal supervision during labor.

The accuracy of measurements of intrauterine pressure during labor: A statistical analysis☆

Abstract For nine patients undergoing labor, the intrauterine pressure of each contraction after rupture of the membranes was recorded by three separated catheters. The resultant data are statistically analyzed by a variety of methods. The main effects of contractions and catheters and the interaction between these effects are examined by the analysis of variance. Components of variance due to each of these three sources and due to random error are estimated. The standard deviation that would be expected had only one catheter been employed is then estimated to lie between 5 and 10 mm Hg. Differences in this last measure of variability are shown to be statistically significant among the nine patients. Finally, a graphical method is used to illustrate the variability of measurement as recorded by different catheters measuring the same contraction.