Prediction Of Fetal Lung Maturity Research Articles

Fetal pulmonary maturity as determined by particle electrophoresis.

Particle electrophoresis has been used to investigate particles obtained from amniotic fluid. These particles are defined mainly as unilamellar and multilamellar liposomes by electron microscopy. A total of 172 samples of amniotic fluids from 132 pregnancies were included in this study. The electrophoretic results were compared to the total phospholipids and to neonatal outcomes in 42 cases. At least two kinds of particles from amniotic fluids with different electrophoretic mobilities (EPM) are evident. With a ratio of F greater than 1.0, the presence of electrophoretically faster particles was found to be associated with apparent fetal lung maturity. On the other hand when the ratio was F less than 1.0, this seems to indicate an immature fetal lung. Seventy-seven per cent of F values correspond to the total phospholipid content P regarding the prediction of fetal pulmonary maturity resp. immaturity. The correct prediction of fetal lung maturity was demonstrated in 42 patients delivered within 48 hours of amniotic fluid sampling. In 28 cases with a mature F value (greater than 1.0) the correct prediction of respiratory distress syndrome (RDS) was 100 per cent. Eight out of 14 patients with immature F values (less than 1.0) developed RDS. The F values were found to increase as pregnancy progressed. The electrophoretically differentiated amniotic fluid particles behave differently at low pH. Selection and electrophoretic measurement of particles were made in a subjective manner. This preliminary investigation suggests that the results correspond to those obtained by objective cell electrophoretic measurements.

Ultrasonically determined menstrual age as an indicator of fetal lung maturity.

The usefulness of ultrasonically determined menstrual age as a predictor of fetal lung maturity has been evaluated in patients without fetal or maternal disease undergoing repeat cesarean section. The menstrual age of each fetus was determined at 18-32 wk using biparietal diameter (BPD) measurements and previously established BPD growth curves. Lung maturity prior to delivery was assessed by measuring the lecithin/sphingomyelin (L/S) in amniotic fluid. The menstrual age at the time of the amniocentesis was derived by extrapolation from the results of the first scan. When the Sabbagha Composite BPD growth curve was used for menstrual age determinations, the L/S was less than 2.0 in all cases before 34 wk, both less than 2.0 and greater than or equal to 2.0 between 34 and 38 wk, and greater than or equal to 2.0 in all but one case after 38 wk. This one case represents 1.2% of fetuses studied. These results suggest that in the absence of fetal and maternal disease, a menstrual age of 38 wk or older, based on an early BPD measurement and use of the Sabbagha Composite BPD growth curve, is indicative of lung maturity in most cases.

Improved prediction of fetal lung maturity in diabetic pregnancies: A comparison of chromatographic methods

Following planned termination of pregnancy, infants of diabetic mothers have shown a continued vulnerability to the respiratory distress syndrome (RDS), suggesting false positive results on fetal lung maturity testing. We studied the adequacy of the standard one-dimensional chromatographic lecithin/sphingomyelin (L/S) ratio for predicting RDS in 56 diabetic and 50 nondiabetic pregnancies. An exceptionally low incidence of RDS was noted for the study (0.95%) as well as for diabetic pregnancies alone (1.85%). The clinical results were further compared to a new method for determining L/S ratios and identifying other pulmonary phospholipids by two-dimensional chromatography. Values for two-dimensional L/S ratios were significantly lower from 36 through 38 weeks' gestation (P less than 0.01), suggesting improved accuracy and a lessened risk for false positive results in preterm deliveries. Positive identification of amniotic fluid phosphatidylglycerol (PG) was related to increasing L/S ratios (P = 0.001), but only 50% of nondiabetic and 16.7% of diabetic amniotic fluid samples contained PG when the L/S was 2:1 or greater (P = 0.02). The identification of PG serves to confirm fetal lung maturity, but the L/S ratio remains the best available indicator of fetal lung maturity for all high-risk pregnancies.

Optical density and surface tension in amniotic fluid in the late pregnancy (author's transl)

113 amniotic fluid samples from pregnant women between the 28th and the 41st week of gestation were examined for optical density and surface tension. Surface tension measurement was done by means of the Wilhelmy-balance which shows a very good correlation with the L/S-ratio. Optical density was measured at 405, 580, 650, 750 and 900 nm wave length. For the comparison with the surface tension optical 650 nm was used, since at this wave length only minimal absorbance of known biologic pigments occurs. Pulmonary maturity was diagnosed when the surface of the hysteresis area (dynamic surface tension measurement) was more than 20 cm2 or when optical density at 650 nm was false positive in 3,7% and false negative in 40,7%. The same percentage was found in the predication of fetal lung maturity by this method after fetal outcome. The measurement of the optical density is a rapid and simple method, but because of the high number of false negative results it is advised to use one of the more sophisticated methods for the prediction of fetal lung maturity in cases of a negative optical density reading at 650 nm.

Phosphatidylglycerol determination on amniotic fluid 10,000 × g pellet in the prediction of fetal lung maturity

Phosphatidylglycerol and the lecithin/sphingomyelin (L/S) ratio were determined, and the shake test was performed, as indicators of fetal lung maturity, in more than 600 patients. A clinical review of the outcome was made in all patients who underwent delivery within 2 days after collection of amniotic fluid. Correlation was made between phosphatidylglycerol, shake test, and L/S ratio results. L/S ratio had a false positive rate of 5%, and a false negative rate of 58.1%. The shake test had a false positive rate of 1.1%, and a false negative rate of 63.5%. Phosphatidylglycerol determination had a false positive rate of 1.8%, and a false negative rate of 26.9%. Phosphatidylglycerol determination is an accurate predictor of fetal lung maturity, and predicts lung immaturity more correctly than do the L/S ratio and shake test.

Improved thin-layer chromatography of disaturated phosphatidylcholine in amniotic fluid.

We describe an indirect test of fetal lung maturity: the quantitation of disaturated phosphatidylcholine in amniotic fluid. The lipids in samples of amniotic fluid from 172 patients were reacted with osmium tetroxide, and disaturated phosphatidylcholine was then isolated by thin-layer chromatography. Interfering substances were retained by a pre-adsorbent layer. The charred disaturated phosphatidylcholine, quantitated by densitometry, was compared to standard dipalmitoyl phosphatidylcholine. Both within-run and between-run coefficients of variation were about 10%. Blood and meconium do not interfere. Six infants developed respiratory distress when disaturated phosphatidylcholine concentrations of amniotic fluid drawn within 72 h of delivery were less than 5.5 mg/L. A concurrently determined lecithin/sphingomyelin ratio falsely predicted lung maturity in one of these. In seven other samples for which lecithin/sphingomyelin ratios suggested lung immaturity but disaturated phosphatidyl-choline predicted maturity, none of the infants developed respiratory distress. In normal pregnancies, measurement of disaturated phosphatidylcholine in amniotic fluid appears to be a better predictor of fetal lung maturity than is measurement of the lecithin/sphingomyelin ratio. Further studies are needed to determine if this analysis is a better predictor in diabetic pregnancies.

High pressure liquid chromatography of standard and amniotic fluid phospholipids

AbstractA method for the HPLC separation of phosphatidylglycerol (PG), phosphatidylinositol (PI), phosphatidylcholine (PC), and sphingomyelin (SPH) was achieved using five in‐series columns packed with LiChrosorb, Partisil, and μ‐Porasil adsorbents, a solvent mixture of chloroform/methanol/ammonium hydroxide (50 : 36 : 6.7, by volume), and a Pye LCM2 Moving Wire (FID) detector. The same phospholipid mixture was also separated using four μ‐Porasil columns with the same eluent and detector. The latter conditions were found to be suitable for the analysis of phospholipids obtained after centrifuging, extraction, and precipitation of surface‐active lipid components of patient amniotic fluid collected at amniocentesis section. The lecithin/sphingomyelin (L/S) ratios, determined by the HPLC method, correlated well with those determined by the TLC technique in four normal pregnancies, whereas results of shake tests did not correlate too well with L/S ratios determined by the above two chromatographic methods. Besides the lecithin/sphingomyelin ratio, the present method was able to supply additional information: the concentrations of phosphatidylglycerol and phosphatidylinositol, for prediction of fetal lung maturity, and the palmitic acid content of amniotic fluid phosphatidylcholine.

Gas chromatographic determination with flash methylation of palmitic acid in amniotic fluid in prediction of fetal lung maturity

A new method for determination of palmitic acid in amniotic fluid was developed. The dipalmitoyl lecithin was hydrolysed, and after extraction the palmitic acid was flash methylated in the injector of the gas Chromatograph. The between batch coefficient of variation was 6.0% at 40 and 70 μmol/1 of palmitic acid concentrations in 500 μ1 amniotic fluid. The accuracy of the method was demonstrated by linearity, recovery and correlation studies. The correlation coefficient was 0.98 between the new and bortrifluoride methylating method. The concentrations of lecithin and palmitic acid in amniotic fluid showed a correlation coefficient of 0.97. If the concentration of palmitic acid falls below 80 μmol/1 respiration distress syndrome is likely. The new method was simple and easy to carry out and could be adjusted for haemoglobin contamination of the amniotic fluid. It was concluded that the determination of palmitic acid in amniotic fluid was a reliable method for the assessment of fetal lung maturity that could replace the determination of lecithin concentration.

Amniotic Fluid Palmitic Acid Concentrations and Prediction of Fetal Lung Maturity

Lindback, T. Amniotic Fluid Palmitic Acid Concentrations and Prediction of Fetal Lung Maturity. Scand. J. clin. Lab. Invest. 36, 689–692, 1976.A method for rapid determination of total esterified palmitic acid concentration (TEPAC) in amniotic fluid is described. The correlation coefficient between the TEPAC and the lecithin concentration was 0.93 in 123 samples of amniotic fluid obtained during the last trimester. The respiratory distress syndrome (RDS) occurred in 73% of the cases studied with TEPAC < 0.072 mmol/1 in predelivery samples. The RDS was not observed with higher concentrations except in cases of maternal diabetes mellitus. The predictive value of total esterified fatty acid studies was confined to the concentration of palmitic acid recorded, and no specific fatty acid distributions or ratios were reliable in identifying RDS or estimating gestational age.

Amniotic fluid palmitic acid concentrations and prediction of fetal lung maturity.

A method for rapid determination of total esterified palmitic acid concentration (TEPAC) in amniotic fluid is described. The correlation coefficient between the TEPAC and the lecithin concentration was 0.93 in 123 samples of amniotic fluid obtained during the last trimester. The respiratory distress syndrome (RDS) occurred in 73% of the cases studied with TEPAC less than mmol/l in predelivery samples. The RDS was not observed with higher concentrations except in cases of maternal diabetes mellitus. The predictive value of total esterified fatty acid studies was confirmed to the concentration of palmitic acid recorded, and no specific fatty acid distributions or ratios were reliable in identifying RDS or estimating gestational age.

The prediction of fetal lung maturity from the surface tension characteristics of amniotic fluid.

In recent years fetal lung maturity has been assessed by chemical determination of lung surfactant components in the amniotic fluid. The variation in the results, however, limits the clinical usefulness of these methods. To establish reliable criteria for fetal lung maturity 98 specimens of amniotic fluid were obtained in the 23rd to 41st week of gestation and their surface properties measured in the surface balance (Fig 1). A continuous rise in surface activity of amniotic fluid was observed during this period (Fig. 2). In the evaluation of the surface activity of amniotic fluid y-min appears to be the most suitable parameter because it shows a considerable change during the course of pregnancy and has low variations (Fig. 3). In 64 prematures amniotic fluid was obtained during delivery and its surface properties measured. The correlation of clinical symptoms of the premature with y-min of the amniotic fluid makes it possible to predict the fetal lung maturity at a given y-min value (Fig. 4). When the results are arranged according to the incidence of RDS (lethal RDS, recovered from RDS and without RDS) three y-min-ranges can be clearly distinguished. When y-min of the amniotic fluid is over 27 dyn/cm the probability of lethal RDS is 100%, whereas when y-min is under 17 dyn/cm a mature lung can be expected. In the range between 27 to 17 dyn/cm any degree of lung maturity can be encountered. By division of this range in two additional ones a more accurate prediction of fetal lung maturity is possible: In the y-min-range 27-23 dyn/cm RDS-probability is approximately 70%, in the range 23-17 dyn/cm it is only 30% (Fig. 4). Measurements of surface activity of the amniotic fluid make it possible to predict fetal lung maturity and estimate RDS-probability.