The frequency of apnea and bradycardia in a population of healthy, normal infants

Twenty-four hour continuous pneumocardiogram recordings were obtained on 250 healthy, normal infants in a hospital nursery on the first to third days of life. 73% of the infants showed no apneic episodes greater than 15 seconds in duration. 5% demonstrated longest apneic episodes greater than 20 seconds in duration with a range up to 32 seconds. 4% showed episodes of periodic breathing and 32% showed bradycardia of less than 80 beats per minute. Subsequent follow-up did not reveal any cases of near miss-SIDS or SIDS. Sustained apnea and periodic breathing appear to be infrequent respiratory patterns in term infants.

Protein synthesis in rat brain following neonatal exposure to lead

(1) Suckling rats were exposed to lead through the milk of their dams who received a diet of 4% lead carbonate and weanling rats were exposed to 2 injections of 5.0 mg Pb2+/100 g body weight. The brains were used to prepare the following homogenate fractions: postmitochondrial supernatant, postmicrosomal supernatant, ribosomes, initiation factors. (2) The postmitochondrial supernatant fractions were tested in vitro for protein synthesizing activity using the incorporation of labelled phenylalanine, and phenylalanyl-tRNA into peptide. The preparations from the lead-exposed rats had a significant reduction in activity. (3) Peptide formation with the brain ribosomes was not changed in the lead-exposed rats. (4) The aminoacyl-tRNA synthetase reaction was significantly reduced and accounted for most of the reduced peptide formation with brain homogenates from lead-exposed rats. (5) The binding of methionyl-tRNAfMet to ribosomes was increased using initiation factor preparations from the brain of lead-exposed rats.

Survival of infants born at 24 to 28 weeks' gestation

Factors affecting the survival of 136 consecutive live-born infants delivered at 24 to 28 weeks' gestation during a 4-year period were analyzed. After careful assessment of gestational age, perinatal care for the fetus of at least 26 weeks' gestation was aggressive. Survival at 26 weeks was 45% and at 28 weeks, 92%. Multivariate analysis showed that the set of variables that best predicts neonatal outcome is gestational age, antepartum glucocorticoid administration, and resuscitation at birth.

Surfactants, L/S ratio, amniotic fluid optical density and fetal pulmonary maturity

Optical density readings of amniotic fluids of 0.15 or greater at 650 nm have been noted to correlate with fetal pulmonary maturity. The amniotic fluid absorbance has been shown to be due not only to lecithin and sphingomyelin but also to other surfactants, including phosphatidyl glycerol and inositol. The addition of lecithin and sphingomyelin to previously centrifuged amniotic fluid (i.e., optical) density less than 0.001: L/S ratio, nondetectable) results in an increase in absorbance. At any simulated L/S ratio, the addition of phosphatidyl glycerol and/or phosphatidyl inositol results in a further increase in optical density. It is suggested that optical density readings represent more closely the surfactant composition of amniotic fluid than L/S ratios; therefore, it appears that optical density measurements are a better predictor of fetal pulmonary development than are L/S ratios.

The effect of cervical/vaginal secretions on measurements of lecithin/sphingomyelin ratio and optical density at 650 nm

Free-flowing amniotic fluid collected vaginally can be used in a reliable way for determination of fetal pulmonary maturity. Lavaging the vaginal/cervical area with sterile saline and examining the lavage fluid for lecithin/sphingomyelin (L/S) spots showed no detectable spots in the supernatants (one exception) and barely detectable L/S spots in the sediment. Vaginal-cervical saline-wash fluids did not affect fluid L/S ratios. Lavaging the vaginal-cervical area with abdominal amniotic fluid did not affect the L/S ratio of the original amniotic fluid.

Amniotic fluid optical density and neonatal respiratory outcome

A simple, rapid, economical, and accurate test to assess fetal pulmonary maturity on a 24-hour basis, 7 days a week, is urgently needed. A 15-minute test has been developed that correlates well with fetal pulmonary maturity. Optical density (OD) readings at 650 nm of greater than or equal to 0.15 in pigment-free, centrifuged (2000 Xg, 10 minutes) amniotic fluids obtained from gestations of 33 to 42 weeks correlate with fetal pulmonary maturity (131 of 131, 100%). When OD readings are less than 0.15 in fluids from gestations of 24 to 40 weeks, and antepartum steroids are utilized, the incidence of respiratory distress syndrome (RDS) is 8.3% (14 of 169). The true false-negative rate in this group is therefore unknown.

Apnea recordings of healthy infants at 40, 44, and 52 weeks postconception

A total of 129 recordings of the respiratory activity of 46 normal full-term infants were obtained continuously for 24 hours in the hospital nursery at 3 days of life and in the home environment at 4 weeks and 12 weeks after birth. The pediatric pneumogram (PPG) technique, an impedance method, was used. Pneumogram data over longer than 16 hours was obtained on 77% of infants monitored. No infants experienced apnea longer than 15 seconds in duration at 40 and 44 weeks postconception, or greater than 11 seconds at 52 weeks postconception. Twenty-four hour plots of hourly apnea frequency revealed a marked variability, with evidence of clustering of apneic episodes during periods of reported sleep. Longest apnea time and hourly frequency of apneic episodes were highly correlated.

Aicardi's syndrome; radiologic manifestations

Features of Aicardi's syndrome include infantile spasms associated with pathognomonic chorioretinopathy, abnormalities of the corpus callosum with heterotopia of gray matter, and characteristic electroencephalographic findings. Vertebral abnormalities are also part of the syndrome, which is apparently limited to female infants. Subnormal mental development appears in all cases. It was first described in 1969 in French. Isolated cases in the literature have been associated with facial asymmetry, plagiocephaly, and the Dandy-Walker syndrome. Experience with two patients suggests that a search for cases among patients with chorioretinopathy and infantile spasms will show the syndrome to be more common than currently reported.

Positive correlation of optical density at 650 nm. with lecithin/sphingomyelin ratios in amniotic fluid

In this study, we have attempted to correlate optical density measurements of amniotic fluids with L/S ratios. We may conclude, with over a 98 per cent accuracy, that fluids having optical density readings of 0.15 and above, at 650 nm. will have an L/S ratio over 2.0. Fluids having optical density readings up to 0.05 will have L/S ratios of about 1.3. Finally, amniotic fluids having optical densities greater than 0.05 and less than 0.15 will have L/S ratios of approximately 1.5.

Relation between optical density at 650 nm and L/S ratios

A simple and rapid test that correlates with L/S ratios has been developed. By centrifuging fresh, unfrozen amniotic fluids at 200g for 10 minutes and measuring the optical density at at 650 nm, correlation with L/S ratios is obtained. Optical density readings of 0.15 or greater correlate 100% with L/S ratios of 2.0 or greater. Optical readings below 0.15 correlate 94% with L/S ratios below 2.0.

Correlation between amniotic fluid optical density and L/S ratio

A test that circumvents the complex methodology needed for the determination of L/S ratios has been developed. It has been observed that the optical density, measured at 400 nm, of supernatants collected from fresh amniotic fluids centrifuged at 2000 g for 10 minutes correlates with L/S ratios.