Normal serum bilirubin levels in the newborn and the effect of breast-feeding

We measured the serum bilirubin concentrations in 2,416 consecutive infants admitted to our well-baby nursery. The maximum serum bilirubin concentration exceeded 12.9 mg/dL (221 mumol/L) in 147 infants (6.1%), and these infants were compared with 147 randomly selected control infants with maximum serum bilirubin levels less than or equal to 12.9 mg/dL. In 66 infants (44.9%), we identified an apparent cause for the jaundice, but in 81 (55%), no cause was found. Of infants for whom no cause for hyperbilirubinemia was found, 82.7% were breast-fed v 46.9% in the control group (P less than .0001). Breast-feeding was significantly associated with hyperbilirubinemia, even in the first three days of life. The 95th percentile for bottle-fed infants is a serum bilirubin level of 11.4 mg/dL v 14.5 mg/dL for the breast-fed population, and the 97th percentiles are 12.4 and 14.8 mg/dL, respectively. Of the formula-fed infants, 2.24% had serum bilirubin levels greater than 12.9 mg/dL v 8.97% of breast-fed infants (P less than .000001). When compared with previous large studies, the incidence of "readily visible" jaundice (serum bilirubin level greater than 8 mg/dL) appears to be increasing. The dramatic increase in breast-feeding in the United States in the last 25 years may explain this observation. There is a strong association between breast-feeding and jaundice in the healthy newborn infant. Investigations for the cause of hyperbilirubinemia in healthy breast-fed infants may not be indicated unless the serum bilirubin level exceeds approximately 15 mg/dL, whereas in the bottle-fed infant, such investigations may be indicated if the serum bilirubin exceeds approximately 12 mg/dL.(ABSTRACT TRUNCATED AT 250 WORDS)

Incidence and severity of intraventricular hemorrhage: 1981-1984

We have examined the trend in the incidence and mortality of intraventricular hemorrhage (IVH) in low birthweight infants from 1981 through 1984. During this time we admitted 407 infants in the first week of life with a birthweight less than or equal to 1500 gm in whom a cranial ultrasonogram or autopsy had been performed. Though the mean birthweight and gestational age, proportion of infants who were inborn, and percentage of infants requiring mechanical ventilation did not change over the 4 years, cesarean deliveries were performed more frequently (P less than .001). The overall incidence of IVH was 62% in 1981, 56% in 1982, 49% in 1983, and 58% in 1984, thus no significant trend was evident. Although the incidence of minor hemorrhages (grades I and II) remained relatively constant, there was a decrease in the incidence of grade III IVH (1981, 11%; 1984, 2%, P = .01). The incidence of grade IV hemorrhage did not change during the 4 years and ranged from 7 to 9%. Mortality rate for all infants weighing less than or equal to 1500 gm and for infants with a minor hemorrhage remained unchanged; however, the mortality rate for infants with a major hemorrhage (grade III or IV) tended to decrease (P = .07). We conclude that although some minor changes in the incidence and mortality have occurred, IVH continues to be a major problem in very-low-birthweight infants at our institution.

Effect of bilirubin on brainstem auditory evoked potentials in the asphyxiated rat

We measured brainstem auditory evoked responses (BAER) in four groups of paralyzed, ventilated, adult rats. Group A (n = 2) received intravenous albumin; group B (n = 5) received bilirubin in albumin; group C (n = 7) was asphyxiated and then received albumin; and group D (n = 19) was asphyxiated and received bilirubin in albumin. When compared with control values, no changes in BAER occurred in groups A or B and only slight changes were found in group C. In group D, seven rats died and seven suffered a marked secondary deterioration of the BAER following recovery, a phenomenon that did not occur in group C (p = 0.02). Bilirubin toxicity appears to be responsible for the changes in BAER but prior asphyxia was necessary for this effect to occur. Because the changes that occurred in group D involved all four major waves, it is not possible to separate out a toxic effect of bilirubin, localized to the auditory nerve and the auditory pathway, from a generalized systemic effect which could cause attenuation of the entire response. The BAER may be useful, however, as a noninvasive means of identifying bilirubin toxicity in the newborn.

Indirect BP monitoring in the newborn. Evaluation of a new oscillometer and comparison of upper- and lower-limb measurements

We compared simultaneous direct (aortic) and indirect (oscillometric) BP measurements in 19 patients admitted to a newborn intensive care unit. Two hundred six indirect measurements were obtained from an upper extremity in 14 patients, and 50 from a lower extremity in five other patients. A regression analysis of paired data over a wide range of BPs showed excellent correlation between measurements obtained with the automated oscillometer and intra-arterial catheters. The oscillometric BP correlated equally well in both upper and lower extremities. Simultaneous upper- and lower-extremity BP measurements were taken in seven infants with low birth weights during the first 12 days of life and in ten normal term 2-to 5-day-old infants. Contrary to some previous reports, systolic, mean, and diastolic pressures were virtually identical at both sites.

Care of low-birthweight and sick newborn infants in community hospitals. Effect of an education program

We studied the effect of an education program on newborn care practices, documented by chart review, in nine community hospitals in central Pennsylvania. Following a visit to each hospital, specific recommendations were made and courses were offered at the regional center. A follow-up review of newborn charts showed significant improvement in newborn care. This kind of educational program, particularly if directed at identified problems in individual hospitals, appears to be effective. In addition, chart reviews can provide the information necessary for assessing both care practices and the effect of an educational program.

Regional cerebral blood flow, cerebral blood velocity, and pulsatility index in newborn dogs

A technique employing a Doppler ultrasound probe to measure cerebral blood velocity was used to study the cerebral circulation continuously in 30 newborn mongrel dogs. Utilizing a transfontanelle approach, the probe was maintained in fixed position throughout a given experiment. In 20 animals, changes in systolic, diastolic, and mean cerebral blood velocity during hypo- and hypercarbia were directly correlated (P less than 0.01) with changes in regional cerebral blood flow (rCBF) determined in 12 regions of the brain by the [14C]iodoantipyrine autoradiography technique. In an additional 10 dogs, multiple determinations of systolic, diastolic, and mean blood velocity were made over a wide range of PaCO2 values and found to be directly related to the PaCO2 (P less than 0.001). These data suggest that changes in cerebral blood velocity are closely related to changes in cerebral blood flow. We also calculated the pulsatility index (PI) from the peak systolic and end diastolic velocities and found a poor, but direct (r = 0.28, P less than 0.05) relationship between the PI and PaCO2 rather than the indirect relationship, which has been suggested in published clinical studies. We conclude that the Doppler technique may be valuable in monitoring dynamic events of the neonatal cerebral circulation if a constant probe position is maintained. Our results suggest, however, that the PI is not a reliable index of cerebral vascular resistance.

Neonatal jaundice in full-term infants. Role of breast-feeding and other causes

Serum bilirubin determinations were performed on 264 term infants who were consecutively delivered via the vaginal route. Forty-one infants (15.5%) had serum bilirubin concentrations greater than 12 mg/dL. No cause for this was found, initially, in 23 (56%) of these infants. On the third hospital day, the mean (+/- SD) serum bilirubin level was 6.9 +/- 3.6 mg/dL in breast-fed infants and 6.5 +/- 3.2 mg/dL in bottle-fed infants. Of the 23 infants without obvious cause for hyperbilirubinemia, eight (four bottle-fed and four breast-fed infants) had serum bilirubin concentrations greater than 12 mg/dL on the third hospital day, whereas in 15 (14 breast-fed infants and one bottle-fed infant), the elevated serum bilirubin level occurred on day 4 or 5. Breast-feeding does not seem to affect the total serum bilirubin level in the first three days of life but may be associated with an increased incidence of hyperbilirubinemia subsequently. In a normal full-term population, routine investigations do not disclose a cause for hyperbilirubinemia in about half of the patients.

Sibling visiting in a neonatal intensive care unit

The effect of sibling visiting in a neonatal intensive care unit was studied. Sixteen siblings of 13 infants were randomly assigned to a visiting or nonvisiting group. Behavioral patterns were measured by questionnaires administered to the parents and by direct observation and interviews with the children. There were no significant changes in the behavior of the children following the birth of their sibling, and there was no significant difference between the behavior scores of the two groups 1 week after the experimental (or control) intervention. The visiting children did not show signs of fear or anxiety during the visit. These data suggest that sibling visiting to a neonatal intensive care unit is not likely to be harmful and might be beneficial to the siblings and their families.

Chemstrip glucose test strips: correlation with true glucose values less than 80 mg/dl

Estimations of blood glucose in the range 0-80 mg/dl were performed using the Chemstrip bG and StatTek Glucose Low Level test strips. Estimations of glucose levels closely approximated values obtained by a quantitative, enzymatic reference method; both appear to be excellent screening tests for hypoglycemia. There were no false-negatives, the tests were 100% sensitive and predicted the absence of hypoglycemia, as defined by a plasma glucose value of less than 30 mg/dl, in every case. Therefore, significant hypoglycemia should not be missed. Both give some false positives; in the usual neonatal intensive care population, about 4 of 10 Chemstrip readings of less than 40 mg/dl would lead to an unnecessary blood glucose determination, an acceptable rate for this type of test. The Chemstrip bG technique, a simple and useful test, should be valuable for blood glucose screening in the nursery.

Infants weighing 1,000 grams or less at birth: developmental outcome for ventilated and nonventilated infants

The neurodevelopmental outcome at a mean age of 40 months was investigated in 23/25 surviving infants of birth weights less than or equal to 1,000 gm. Eight infants required intubation and assisted ventilation and 17 were not ventilated. One ventilated infant was lost to follow-up and one nonventilated infant was a victim of sudden infant death syndrome at age 6 months. Fifteen (65%) had a good outcome but the differences between ventilated and nonventilated infants were striking. Thirteen (81%) of the nonventilated group were normal, but only two ventilated survivors (28%) were normal (P less than 0.05). Cicatricial retrolental fibroplasia occurred in three (43%) of the ventilated survivors and in none of the nonventilated infants (P less than .02). The requirement for assisted ventilation in these very low-birth-weight infants is associated with significant morbidity. Improvement in outcome may depend as much upon better understanding and management of prenatal events as upon improvements in neonatal care.

The clinical significance of placental villous edema

A study was undertaken to determine why there is such variability in morbidity and mortality in neonates exposed to antenatal chorioamnionitis. Villous edema provides a clue. It was present in 72/83 placentas with chorioamnionitis. The extent and severity of the edema had a strong, positive correlation with cord arterial blood pH values, low Apgar scores, the need to resuscitate vigorously at birth, the subsequent need for assisted ventilation, the frequency of hyaline membrane disease, and neonatal mortality. Most of the difference in morbidity and mortality between preterm and full-term infants was related to the greater severity and extent of villous edema in those born prematurely.

Serum potassium changes following packed red cell transfusions in newborn infants

We studied the effect of packed red cell transfusions on serum potassium levels in sick newborn infants. In 11 transfusions the infants' serum potassium levels fell from a mean of 5.1 +/- 1.2 mEq per 1 (SD) to 4.9 +/- 1.2 mEq per 1 within 1 hour of the transfusion. Plasma potassium in stored packed red cells rose markedly within 48 hours of drawing. In spite of this, the transfusion of 10 ml per kg of packed red cells did not affect the serum potassium concentration in the newborn infant.

Use of peripheral intravenous cannulas in premature infants: a controlled study

A randomized, controlled study was done to determine whether a 25-gauge steel needle or a 24-gauge Teflon catheter was preferable for the administration of peripheral intravenous fluids and medications to premature infants. A total of 58 cannulas--28 steel needles and 30 catheters--were used in 34 infants. The needles remained in place for 15.4 +/- 13.2 hours (mean +/- SD) and the Teflon catheters for 49.5 +/- 30.9 hours (mean +/- SD). All of the steel needles had to be removed because of infiltration whereas only 17/30 (57%) of the catheters infiltrated. A local inflammatory reaction, which was not related to infection, occurred with 11/30 (37%) of the Teflon catheters. Following removal, Staphylococcus epidermidis was grown from the culture of 1/19 steel needles and 1/25 catheters. In both instances this organism was thought to be a contaminant. Teflon catheters remain functional three times longer than steel needles with no apparent increase in complications. The use of these catheters, therefore, appears to be the preferred method for administering intravenous fluids to premature infants.

Transcutaneous bilirubin measurements in full-term infants

A total of 292 transcutaneous bilirubin (TcB) measurements were performed in 157 white full-term infants: 157 were obtained from the forehead and 135 from the midsternum. TcB measurements correlated well with serum bilirubin determinations (r = .93, P less than .0001). The sensitivity of the test was 100% and the specificity 97%. It was possible to establish guidelines for the TcB measurement which identified all infants whose serum bilirubin concentrations exceeded 12.9 mg/100 ml (221 mumoles/liter) with no false-negative and only five false-positive determinations (3%). The positive predictive value for the TcB measurements was 58%. This implies that, in our population, an infant with a TcB index greater than or equal to 24 has a 58% chance of having a serum bilirubin concentration greater than 12.9 mg/100 ml. The negative predictive value was 100%. Thus, a negative test will correctly predict the absence of hyperbilirubinemia in all cases. As these measurements were obtained prospectively in a well-baby population with a prevalence of hyperbilirubinemia (greater than 12.9 mg/100 ml) of 4.5%, the positive predictive value should be applicable to other similar populations and will, in fact, increase in populations with a higher prevalence of hyperbilirubinemia. TcB measurements can be recommended for the identification of significant neonatal jaundice in full-term infants. It is important to recognize, however, that because of potential variations in TcB meters as well as serum bilirubin measurements in different laboratories, each institution should establish its own criteria for the use of this instrument.