Neonatal hyperviscosity: I. Incidence.

Capillary hematocrits were performed on 790 infants during the first four hours after birth. These infants were delivered between August 8 and December 7, 1974, at the University of Colorado Medical Center, which is at an altitude of 1,061 m above sea level. When the capillary hematocrit was 7% or greater, venous hematocrit and blood viscosity were determined. Capillary hematocrits obtained from warmed heels in the first hour after birth were spuriously high and not consistently related to venous hematocrit. Venous polycythemia, defined as a hematocrit of 65% or greater, occurred in 4% of the newborn population. Hyperviscosity (greater than 2 SD above the mean for newborns) occurred in 5% of the newborn infants. At a venous hematocrit of 65% or greater, hyperviscosity was predictable, but some infants with venous hematocrits between 60% and 64% also had hyperviscosity of the blood. The incidence of polycythemia and hyperviscosity was further related to birth weight and gestational age. The infants who were small for gestational age were at highest risk of polycythemia and hyperviscosity, followed by infants who were large for gestational age. However, the greatest number of infants with hyperviscosity were term appropriate for gestational age. Preterm infants with gestational ages of less than 34 weeks were not affected.

Neonatal hyperviscosity. II. Effect of partial plasma exchange transfusion.

To determine the effect of partial plasma exchange transfusion, 20 newborn infants with neonatal hyperviscosity were randomly assigned to observation or treatment with partial plasma exchange transfusion within the first eight hours after birth. They were studied for organ involvement by roentgenogram, blood count, coagulation studies, and neurologic behavior and were followed up using the Brazelton Neonatal Behavior Assessment scale at 8, 24, and 72 hours and 2 weeks of age; in addition, ten control infants without hyperviscosity of similar birth weights and gestational ages were also studied. Exchange transfusion improved blood viscosity but both hyperviscous groups showed a higher proportion of abnormal results than did the control subjects. Infants receiving exchange transfusions subsequently improved during the period from 8 hours to 2 to 3 weeks of age, until they were indistinguishable from the control subjects. Neurologic improvement in hyperviscous infants who had not received exchange transfusions were significantly slower during this period. At 8 months of age, abnormal neurologic and developmental findings were impressive in both groups; no significant differences in neurologic abnormalities were noted at that time. Developmental delays, tremors, spastic diplegia, and monoparesis were found in four of six untreated infants and five of ten infants who had received exchange transfusions. A fine tremor was present in one control child.

Evaluation of an elastomeric holographic index-matching medium.

A transparent silicone elastomer is evaluated for suitability as an index-matching material for holography. Transparency, index of refraction, adhesion, dimensional stability, and optical activity are determined. Trials conducted in a student laboratory yield positive results.

Plasma zinc levels in premature infants receiving parenteral nutrition.

Plasma zinc levels in premature infants receiving parenteral nutrition without supplementation of trace elements were evaluated. The mean +/- SE for plasma zinc concentration prior to the start of parenteral nutrition was 53 +/- 6 microgram/dl. During the first two weeks of parenteral nutrition the levels remained low, but did not change significantly. However, from day 14 through day 32 there was a statistically significant (P less than 0.05), progressive decline in plasma zinc values. Perhaps the shortened gestational periods were etiologic in producing the initial low plasma zinc concentration in these patients. Since low-birth-weight infants apparently have a high requirement for zinc, the reduced growth rates of these patients may be related to their apparent zinc deficiencies.

Trace element metabolism in the fetus and neonate.

The effects of trace metal nutrition on the fetus and neonate have been described. Since very little research has been done with the human fetus and neonate, much of our knowledge must be extrapolated from animal studies. In addition, most of the work centres around the effects of copper and zinc nutrition. Nutritional requirements (when known) for both enteral and total parenteral feeding of certain trace metals, as well as the bioavailability, have been discussed. Finally, methods of assessment of trace metal nutritional status have been discussed. These include direct measurement of metal concentrations and determination of biochemical indicators, such as metal-dependent enzyme activities--both of which are static indicators of nutritional status, and functional assessment of nutritional status which is a dynamic measure of trace metal nutrition and includes tests measuring the effects of metal nutrition on the function of cells, tissues, organs, and the host in general.

Zinc and total parenteral nutrition.

Present knowledge of trace element nutritional requirements and the effects of TPN solutions unsupplemented with zinc indicate that zinc supplementation must be considered for any patient receiving prolonged TPN. Zinc sulfate appears to be the supplement of choice, and infusions of freeze-dried plasma appear to be an unsatisfactory method for supplying zinc, even during short-term therapy. As long as accepted dosage regimens are followed, there appears to be little risk of toxicity when TPN solutions are supplemented with zinc.

Technique of handling neonatal blood samples for zinc analysis.

Short segments of Chemfluor flexible Teflon tubing (2.38 mm ID) previously coated with sodium heparin (1,000 units/ml) serve as ideal containers in which blood from neonates can be collected for zinc analysis. The ends of the tube are plugged with Teflon TFE round beading so that the sample comes in contact only with Teflon and the risk of contamination is minimized. The heparin coating facilitates easy collection of the sample and separation of plasma by centrifugation. It does not contribute zinc to the specimen.

Effect of lactose on mineral absorption in preterm infants.

To determine whether a reduction of dietary lactose affects mineral absorption in preterm infants, a controlled, randomized, 72-hour balance study was conducted with very low birth weight infants (birth weights less than 1400 gm) fed Similac Special Care formula with a 50:50 carbohydrate blend of glucose polymers and lactose (n = 8) or a nearly identical formula with 100% carbohydrate as lactose (n = 10). The studies were conducted after at least 3 consecutive days of full oral feeds at a mean age of approximately 23 days. There was no difference between groups in percentage of apparent absorption of calcium, phosphorus, magnesium, zinc, copper, or manganese. Retention of these nutrients was similar to or greater than that which occurs in utero. Calcium absorption was 75% of intake. These results indicate that reducing the lactose content of premature-infant formulas to 50% of the carbohydrate does not impair mineral absorption.

Thick blood syndrome.

Twenty cases of hyperviscosity were studied prospectively to determine the presence and incidence of radiological findings and whether or not exchange transfusion had an appreciable effect on these findings. Serial chest radiographs revealed increased pulmonary vascularity, hyperaeration, and mild, bilateral alveolar infiltrates (perihilar and/or lower lobe). Ten patients were treated with partial plasma exchange transfusions which resulted in improvement of radiological findings. Hyperviscosity is more common than previously recognized. This entity may have profound significance as a potentially treatable cause of central nervous system damage in the neonate.

Soft-tissue repair of myelomeningocele defects using bilateral latissimus dorsi and trapezius musculocutaneous flaps.

An urgent closure of myelomeningocele defects was carried out in 82 newborns using latissimus and/or trapezius musculocutaneous advancement flaps. A three-layer closure of skin, muscle, and fascia was achieved in a single stage without a flank skin graft. All of the wounds healed within a two-week period and no late breakdown of the wound occurred during the eight-year period of study. The urgent closure maximized the neurological salvage and facilitated early cerebrospinal fluid shunting by preventing both infection and neural desiccation. This report represents the largest number of sequentially treated myelomeningocele defects without a major wound healing problem or death. The advancement musculocutaneous flap closure is safe, simple, and effective and is recommended as the preferred method for closure of the myelomeningocele defect.

Developmental pharmacokinetics of mezlocillin in 4 newborn infants.

The disposition of mezlocillin was evaluated in 4 newborn infants in a sequential two-phase study at postnatal ages of 1 day and 8 or 10 days. Renal function was estimated by creatinine clearance (CLCR) and pharmacokinetic parameters of mezlocillin was were determined from serum concentrations and urinary excretion rates. All weight-normalized mezlocillin clearances (total, renal, and nonrenal) and CLCR were less than adult values, but increased after 8 or 10 days of mezlocillin therapy and postnatal development. The volume of distribution at steady state did not significantly change throughout this period, and approximated the expanded extracellular fluid volume typically found in neonates. The elimination half-lives were substantially shorter by phase II of the study. Both renal and nonrenal elimination processes were enhanced by 1 week of postnatal development even though body weight did not increase. Mezlocillin disposition in neonates is thus affected by body weight, gestational age, and postnatal age.

Developmental pharmacokinetics of mezlocillin in newborn infants.

Single-dose pharmacokinetics of mezlocillin were studied in 53 newborn infants (72% less than or equal to 36 weeks' gestation) given ampicillin and an aminoglycoside for suspected or proved sepsis. Mezlocillin (75 mg/kg IV or IM) was substituted for ampicillin, serum was assayed microbiologically, and noncompartmental pharmacokinetic parameters were calculated. Analysis of covariance showed that dose/area under the serum concentration-time curve for mezlocillin was influenced by body weight, intramuscular administration, and treatment with gentamicin. A dual intravenous/intramuscular nonlinear regression model yielded an apparent intramuscular bioavailability of 84%. Clearance was proportional to body weight (WT) (r2 = 0.70). Mean CL/WT (0.078 L/hr/kg) was one-half adult values and influenced by gestational age. Steady-state volume of distribution varied linearly with weight (r2 = 0.80), the mean value (0.38 L/kg) being twice that in adults. Mezlocillin half-life (mean 3.71 hours) exceeded adult values and did not correlate with weight. Twenty-four newborn infants received 75 mg/kg mezlocillin every 6 or every 8 hours, along with gentamicin, during the first 7 to 10 days of life. Peak (1.5 hours) and trough (6 or 8 hours) concentrations were determined; the latter decreased from day 3 to days 7 to 10, suggesting a possible postnatal age-dependent change in mezlocillin elimination. Although mezlocillin disposition is affected by age and therapeutic factors, weight alone may adequately predict dosing requirements.

Congenital malformations and psychosocial development in children conceived by in vitro fertilization.

To determine whether in vitro fertilization (IVF) as a method of conception is associated with an increased risk for congenital malformations or developmental dysfunction, we performed a general physical examination for malformations, neurologic examination, developmental examination (Bayley Scales), echocardiography, electrocardiography, abdominal ultrasound study, and, when possible, cranial ultrasound examination on a cohort of 83 IVF children and 93 matched non-IVF children. Major malformations were found in two IVF and one non-IVF subject; the rates were not significantly different. The mean Mental Development Index scores for IVF subjects and the comparison group were 115 +/- 13 and 111 +/- 13, respectively (p = 0.12). The mean Psychomotor Development Index scores were 114 +/- 14 and 108 +/- 15 (p = 0.04). Based on these small numbers but extensive evaluation, we found no association between conception by IVF and an increased risk for congenital malformations. Likewise, children conceived by IVF showed no evidence of developmental delay. Their high average achievement on the Bayley tests probably resulted from the exceptional motivation of their parents ("wantedness") and their generally high socioeconomic status.