Very low birth weight infants have only few adverse events after timely immunization.

INTRODUCTION: Premature infants should be vaccinated at the appropriate vaccinating age, without correcting for their gestational week and regardless of their weight. Uncertainty with regard to possible severe adverse events exists among physicians. METHODS: In all, 473 patients with a birth weight under 1500 g were included in a prospective observational study for adverse events that included cardiorespiratory events, local reactions and fever. Three vaccination combinations were used at different time periods. RESULTS: The median birth weight was 910 (375 to 1495) g. Gestational week at birth was 27.6 (22.6 to 34.3). At the time of vaccination, the gestational week was 37.4 (31.5 to 48.3). The frequency of adverse events for local reactions/fever was 2.8% and for apnea/bradycardia it was 10.8%. Apnea appeared significantly more often in children who were younger at the time of immunization. This is in concordance with the fact that they were also younger at birth. If apnea appeared, the chance of the development of bradycardia had an odds ratio of 6.4 (3.2:13.0). Children with higher-grade hemorrhages and/or with periventricular leukomalacia did not experience more adverse events, except fever. CONCLUSION: Timely vaccination of premature infants with a birth weight under 1500 g is safe, but the occurrence of cardiorespiratory events is related to earlier gestational week.

Hyper-releasability of mast cells in family members of infants with sudden infant death syndrome and apparent life-threatening events.

BACKGROUND: An allergic reaction with increased degranulation of mast cells has been suggested as a possible mechanism in sudden infant death syndrome (SIDS). STUDY DESIGN: Mast cell releasability was assessed in 2 study groups: A, 22 subjects, 16 first-degree relatives of infants who had had an apparent life-threatening event (ALTE) and 6 infants after ALTE and B, 46 first-degree relatives of SIDS cases. These groups were compared with 71 members of an age-matched control group. In each subject the skin wheal and flare reactions were measured after an intradermal injection of 0.02 mL of each of the following substances dissolved in phenol-saline solution: histamine 0.0001 mg/mL, histamine 0.001 mg/mL, codeine 0.5 mg/mL, codeine 1 mg/mL, compound 48/80 0.05 mg/mL, compound 48/80 0. 1 mg/mL, and phenol-saline solution. The size of wheal and flare skin reaction was assessed by computerized planimetry after the shape of the cutaneous response was copied onto a paper. RESULTS: The wheal and flare skin reaction to each of the substances was significantly larger in the 2 study groups compared with the control group (P <.05) except for the wheal reaction to compound 48/80 0.1 mg/mL, codeine 0.5 mg/mL, and histamine in both concentrations for group A and the wheal reaction to codeine 1 mg/mL and histamine in both concentrations for group B. All individuals with increased reaction belonged to 3 (50%) of 6 families with ALTE history and to 8 (73%) of 11 families with SIDS history. CONCLUSIONS: Increased mast cell hyper-releasability and degranulation take place in family members of some SIDS and ALTE cases and in some infants with ALTE, supporting a possible role for an immunologic mechanism in the pathophysiology of these entities.

Passive transfer of methacholine sensitivity from man to monkey.

A model of human allergic disease, in which nonhuman primates were infused with serum from allergic humans and challenged with appropriate antigen, was used to determine whether the animals also develop hyperreactive airways characteristic of asthma. Anesthetized monkeys were insufflated with increasing concentrations of methacholine aerosol, and changes in pulmonary function were measured. Airway reactivity as assessed by the dose of methacholine aerosol culminating in apnea was determined after infusion of serum from allergic or nonallergic humans or with heated allergic serum. A comparison of the results indicated that only infusion of unheated serum from allergic humans resulted in an increase in airway reactivity to aerosolized methacholine. These results suggest that a factor in the serum of allergic humans may play a role in the hyperreactivity of airways characteristic of asthma.

Effect of naltrexone on apnea of prematurity and on plasma beta-endorphin-like immunoreactivity.

Plasma levels of beta-endorphin-like immunoreactivity (beta-ELI) were measured in premature infants with apnea (n = 11) and compared to those in nonapneic controls (n = 9). Naltrexone (1-3 mg/kg) was given to the infants with apnea, 6 of whom were also receiving methylxanthines. Chest wall movements, nasal airflow, transcutaneous PO2 and electrocardiogram were recorded for 4-6 h prior to and for 4-6 h after administration of naltrexone. Samples for beta-ELI were taken prior to and 1 h post naltrexone. beta-ELI levels were significantly higher (p less than 0.007) in infants with apnea of prematurity than in control infants. No significant difference was found in beta-ELI levels before and after naltrexone. Naltrexone did not decrease the incidence of apnea.