Edwin G. Brown

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.

The early use of continuous positive airway pressure in the treatment of idiopathic respiratory distress syndrome

Infants with IRDS were treated with CPAP early (0.40 Fi O 2 O 2 ; Pa O 2 O 2 (maximum 0.55) and had a less severe clinical course. The late treated infants were subjected to 0.70 or more Fi O 2 for an average of 24 hours and were in greater than 0.40 Fi O 2 significantly longer than those given CPAP early. Infants who weighed less than 1,500 gm and had severe disease did not do well regardless of when CPAP was applied.

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.

Accuracy and clinical utility of an oxygen saturation catheter.

Twenty-three fiberoptic catheter oximeters were placed in the umbilical arteries of 22 neonates to determine the accuracy and reliability of the sensor and clinical utility of continuous measurement of arterial oxygen saturation. Comparison of fiberoptic saturation readings with 1039 bench measured blood samples revealed a correlation coefficient of 0.97 with a mean error of 0.74 +/- 2.17 (SD) saturation. Although 11 catheters remained reasonably accurate (in error less than 3% saturation) for up to 488 h of use, 12 required in vivo calibration at a median time of 31 h after initial insertion. Clinical use of the catheter oximeter was evaluated in 11 infants by comparison to matched controls. Control infants required 55% more arterial blood samples for care, twice the number of transfusions, and spent twice the amount of time with a PaO2 greater than 110 torr. The catheter oximeter was found to be a useful clinical tool. Saturation values up to 95% reflected accurately and reliably an infants arterial saturation status, providing constant and comprehensive assessment of clinical variations and the effects of therapy. The most useful feature was its rapid and accurate response to hypoxic incidents and to efforts to correct these conditions for improved care of infants in life-threatening situations.

Blood volume and blood pressure in infants with respiratory distress

Mean aortic blood pressure volume were measured in true premature infants with respiratory distress syndrome. Seven infants had Type I RDS (hyaline membrane disease) and ten had transient tachypnea of the newborn (Type II RDS). Blood volume in the infants with Type I RDS was significantly lower than in the infants with Type II RDS. The difference was due to a low red cell volume. Mean aortic blood pressure was within the range of normal in all infants and therefore did not reflect the low blood volume of infants with Type I RDS. Normal mean aortic blood pressure does not indicate normal blood volume or normal circulation in infants with RDS.

THE RELATIONSHIP OF FEEDING TO NECROTIZING ENTEROCOLITIS

The records of all newborns with necrotizing enterocolitis (N-E) were reviewed for the years 1968-73. Of the 24 cases, 19 died & N-E was confirmed in all 18 autopsies. The previously reported associations with low birth weight, PROM or amnionitis, asphyxia, & RDS were found. Also, a relationship with feeding was seen—the infants forming 3 groups: Group I-18 infants begun on formula feedings between 4 hrs. to 8 days of life. They developed G.I. signs an average of 31 hrs. later (S.E.=5.6). Formula intake by the 2nd day of feeding averaged 72 cc/kg/day, 133% of the usual daily formula intake in this nursery for infants without overt illness. All 5 who lived (of which none perforated or had surgery) were in this group. Group II-3 infants developed the onset of G.I. signs 15, 20 and 28 days following initiation of feeding, but had other intercurrent problems. Group III-3 infants never fed formula. These had no x-ray or autopsy evidence of pneumatosis. In these 24 patients with N-E, 75% developed the disease related to the onset of feeding. The remainder appeared to develop their disease in relationship to other problems. Formula feeding in this series is very closely associated with the development of N-E, particularly over-aggressive feeding. Feeding is not the sole cause of N-E but is closely enough related to its development to warrant delayed and cautious feeding of infants at risk of N-E.

Intracardiac thrombi complicating central total parenteral nutrition: Resolution without surgery or thrombolysis

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Use of polyethylene glycol-bound superoxide dismutase, polyethylene glycol-bound catalase, and nimodipine to prevent hypoxic ischemic injury to the brain of newborn pigs

ObjectiveTo determine if polyethylene glycol-bound superoxide dismutase and catalase and nimodipine, alone or in combination, will ameliorate hypoxic ischemic injury to the brain. SubjectsA total of 78 newborn (0 to 3 days) pigs were used. DesignProspective, blinded, randomized, controlled trial. InterventionsThe piglets were subjected to hypoxic ischemic brain injury. Carotid arteries were ligated at time 0 and BP was reduced one third by hemorrhage. At 15 mins, Fio2 was reduced to 0.6. At 30 mins, carotids were released, blood was reinfused, and Fio2 was increased to 1.0. Pigs were randomly assigned at time 35 mins to receive either: 10,000 U/kg of polyethylene glycol-bound superoxide dismutase and catalase (group 1); 0.5 mg/kg of nimodipine (group 2); both 10,000 U/kg of superoxide dismutase and catalase and 0.5 mg/kg of nimodipine (group 3); or no drugs (controls). MeasurementsThe time after reoxygenation for return of electroencephalogram, respiration, blink and pain were recorded in minutes as well as a neurologic examination at 1, 2, and 3 days and pathologic examination of the brain at 3 days, both by blinded observers. Main ResultsThere were no significant differences in the four groups. ConclusionsPolyethylene glycol-bound superoxide dismutase and catalase, and nimodipine, either alone or in combination, do not ameliorate hypoxic ischemic injury to the brain in the newborn pig when given 5 mins after reoxygenation. (Crit Care Med 1993; 21:252–259)

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.

Fructose-1,6-bisphosphate does not ameliorate hypoxic ischemic injury to the central nervous system in the newborn pig.

Background and MethodsFructose-1, 6-bisphosphate has been shown to improve the outcome of hypoxic ischemic brain injury in adult rabbits. We wished to see if these results could be extended to a newborn animal. Twenty-four 0− to 3-day-old piglets were randomized to receive 300 mg/kg of fructose-l,6-bisphosphate 5 mins before injury, followed by a continuous infusion of 15 mg/kg/min of fructose-1,6-bisphosphate for the next 90 mins, or the equivalent volume of normal saline. Hypoxic ischemic central nervous system damage was induced by ligating both carotid arteries and reducing their BP to two thirds of the normal value for 30 mins. hi the last 15 nuns of this 30 mins, the Fio2 was reduced to 0.6. At 30 mins, the piglets were resuscitated with an FIO2 of 1.0, the carotid ligatures were released, and the removed blood was reinfused. ResultsThe neurologic examination scores at 1, 2, and 3 days after injury and pathologic examination scores at 3 days after injury were not different in the fructose-l, 6-bisphosphatetreated and the control animals. ConclusionFructose-1, 6-bisphosphate does not ameliorate hypoxic ischemic brain injury in the newborn pig. (Crit Care Med 1992; 20:1309–1314)