Immunogenicity of hepatitis B vaccine in healthy very low birth weight infants.

We studied the immunogenic response to hepatitis B vaccine of infants weighing < or = 1500 gm at birth. Infants were divided into two groups: those weighing < or = 1000 gm (n = 22) and those weighing 1001 to 1501 gm (n = 28). When immunized early (3 days of age, n = 25), these infants had a response rate (defined as antibody to hepatitis B surface antigen titer > 10 mIU/ml) of 68%, whereas when the first vaccine was given at 1 month of age (n = 25), a 96% response rate was noted, irrespective of birth weight and weight at the time of immunization (p < 0.02).

Effect of vegetable and marine oils in preterm infant formulas on blood arachidonic and docosahexaenoic acids.

Adding docosahexaenoic acid (DHA) (22:6n-3) to formulas is more effective than increasing formula alpha-linolenic acid (18:3n-3) in maintaining blood phospholipid DHA levels similar to those in breast-fed infants. However, in long-term trials supplementary DHA given as marine oil reduces blood phospholipid arachidonic acid (AA) in preterm infants. This effect is not seen in short-term trials unless the total n-3 intake from marine oil exceeds 0.5% of the total fatty acids. In addition, there is considerable variability among individual preterm infants in blood phospholipid AA and DHA levels that is not dependent on diet. Within dietary treatments, a significant positive correlation between AA and DHA concentrations suggests that factor(s) other than marine oil supplementation affect both AA and DHA status. Docosahexaenoic acid and AA concentrations in plasma phospholipids are significantly correlated with DHA and AA concentrations in red blood cell phospholipids, suggesting that the observed individual differences in DHA and AA within groups represent true differences in fatty acid status. Preterm infants appear to be vulnerable to a poor status of both DHA and AA; further feeding trials are needed to identify the optimal balance of fatty acids for feeding these infants.

The effects of single infusion of hypertonic sodium bicarbonate on body composition in neonates with acidosis.

Acid-base equilibrium and plasma and red blood cell water and solute were evaluated in a group of asphyxiated, acidotic neonates prior to and following infusion of hypertonic NaHCO3. The dose was calculated to correct the deficit of base in a bicarbonate space of 400 ml/kg and was given at a rate of 0.3 mM NaHCO3/kg/minute. All of the infants with RDS and two of the five with other forms of asphyxia received ventilatory assistance during the infusion. The quantity of base infused was sufficient to alter acid-base balance and shift whole blood and red blood cell pH values toward normal. The changes in body composition 3 minutes following the infusion indicate that the osmotic load imposed by the hypertonic NaHCO3 caused a shift of solute-free water into the interstitial and intravascular fluids. During the period from 3 to 30 minutes following the infusion there was redistribution of extracellular water and solute so that plasma volume and [Na]PL decreased. Since there was no evidence of an intracellular shift of solute, we hypothesize that the changes in body composition between 3 and 30 minutes postinfusion were in part the consequence of gradual penetration of transcellular fluids by Na. Osmotic inactivation of ECF Na by sequestration with connective tissue polyelectrolytes may also play a role. These studies' do not provide an answer to the clinical problem of whether the beneficial effects of prompt correction metabolic acidosis outweigh the potenially harmful effect of the osmotic alterations that accompany rapid infusion of hypertonic NaHCO3.

Protamine sulfate titration for heparin activity in neonates with indwelling umbilical catheters.

A rapid, simple, semimicro method for neutralization of heparin effect by titration with protamine sulfate is described. Protamine sulfate can be effectively employed to eliminate the effect of heparin on the APTT. Determination of true abnormalities of coagulation has important prognostic and therapeutic implications for the sick newborn infant.