The influence of nutrition on neonatal respiratory muscle function

5-HT(2A/2C) receptor-mediated hypopnea in the newborn rat: relationship to Fos immunoreactivity

Previous data derived from anesthetized, decerebrate, or in vitro preparations suggested that 5-HT(2) receptor activation might be responsible for respiratory dysfunction. Such a mechanism has not yet been documented in the intact animal, but might be of clinical relevance to the apneic spells of the premature infant. In the present investigation on conscious newborn rats we analyzed the respiratory response to the activation of 5-HT(2A/2C) receptors by the agonist 1-(2.5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI), and we delineated central structures possibly involved in this response, using Fos expression as a marker of neuronal activation. We demonstrated that intraperitoneal injection of 5 mg/kg DOI produced a long-lasting decrease in respiratory frequency and tidal volume, which could be blocked by the antagonist ritanserin. Fos immunohistochemistry suggested that the rostral ventrolateral medulla and the lateral paragigantocellular nucleus might have a key role in the respiratory response to 5-HT(2) receptor activation. In addition, double immunostaining for Fos and tyrosine hydroxylase suggested that the contribution of catecholaminergic neurons to this response might be modest and indirect.

Serial copper and ceruloplasmin levels in African newborns with emphasis on the sick and stable preterm infant, and their antioxidant capacities

Literature on serum copper (Cu) and its antioxidant protein (ceruloplasmin) in the African newborn is infrequent, and more reports are evident from developed or affluent societies. We, therefore, studied longitudinally our newborns to delineate their Cu and ceruloplasmin (CLP) status. All infants were born between July 1st, 1991 and June 30th, 1992 at the University of Maiduguri Teaching Hospital, Maiduguri, Nigeria. The preterm infants (PI) (gestational age < or = 36 weeks) were divided into 2 cohorts; A, sick and B, stable; commencing with n = 30 in each group. The groups were matched in respect to gender, gestational age, birthweight, Apgar scores and socioeconomic class. Cu levels were contemporaneously also determined in 30 (M:F, 17:13) stable full-term infants (appropriate-for-dates). Cu determination was made with atomic absorption spectrophotometry and CLP according to colorimetric P-phenylenediamine assay. Sick PI (cohort A) had significantly lower mean (SD) Cu and CLP levels at birth; 0.1 (0.2) micromol/ml and 0.5 (0.8) micromol/dl vs 0.6 (0.2) micromol/ml and 12.5 (1.2) micromol/dl in stable PI (cohort B), respectively; P < 0.05. Cu level was significantly increased by 4 weeks in cohort A; P < 0.001 (n = 25) and approached levels of the stable PI (0.7 (0.3) vs 0.8 (0.2) micromol/ml). Concerning CLP, however, catch-up of levels was delayed till 8 weeks, and a triphasic pattern of linear rise in Cu (both cohorts, but more prominent in A) and CLP (cohort A) was discernible by 24 weeks. The sick PI had mean (SD) serum CLP levels of 0.5 (0.8) micromol/dl, 5.9 (1.4), 15.2 (2.6), 17.3 (2.9), 21.2 (3.8), 25.1 (4.7) and 23.7 (3.8) micromol/dl at birth, 4, 8, 12, 20, and 24 weeks, respectively and were similar from 8 weeks in cohort B. Generally, CLP paralleled serum Cu levels. Cu levels in the full-term infant (FI) were higher at birth and became similar to PI's from 12 weeks, but were overtaken by levels in PI (both cohorts) at 24 weeks. The FI's Cu was significantly elevated by 8 weeks; mean (SD), 0.81 (0.16) micromol/ml vs 1.25 (0.19) micromol/ml; P < 0.01, paired t-test. Decreased growth rate, nonpitting pedal edema, exaggerated physiological anaemia and chronic lung disease were few morbidities noted in association with very low Cu and CLP levels (n = 15). Newborns with serum Cu and CLP>0.2 micromol/ml and >2.3 micromol/dl, respectively, did not have a poor outcome. It is tempting to suggest that absent serum CLP activity may portend a poor prognosis. Our findings (number albeit small) could be taken as a preliminary normative data for further comparisons.

Tolerance of mixed lipid emulsion in neonates: effect of concentration

AIMS

To compare the effect of concentration of a mixed lipid emulsion (50:50 medium chain triglyceride/long chain triglyceride) (MCT/LCT) on lipid tolerance in neonates.

METHODS

A prospective randomised controlled trial of 75 neonates requiring prolonged parenteral nutrition was conducted in the neonatal intensive care units of the Royal Maternity Hospital, Belfast, and the Waveney Hospital, Ballymena. Thirty eight infants received 10% and 37 20% lipid emulsion. Infants were randomly assigned to groups at the start of parenteral nutrition and studied if they required seven or more days of this. Lipid tolerance was assessed by twice weekly measurements of plasma triglyceride and cholesterol concentrations and weekly measurement of non-esterified fatty acids and beta hydroxy butyrate. Anthropometry was carried out weekly.

RESULTS

The mean cholesterol in the 10% group was significantly higher within the first seven days of the study compared with the 20% group (3.5 vs 2.87 mmol/l), and continued to rise over the study period in contrast to the 20% group. A similar pattern was observed with the triglyceride concentrations. There was no significant difference in non-esterified fatty acids, beta hydroxy butyrate, or growth between the two groups.

CONCLUSION

Sick neonates show better biochemical tolerance to 20% MCT/LCT emulsion than to 10% emulsion.

Prolonged mechanical ventilation in children

Improvements in neonatal and pediatric intensive care have produced a growing population of children dependent on mechanical ventilation for survival. Long-term mechanical ventilation has become a realistic alternative to death from progressive respiratory failure for many children with chronic respiratory illness. This article reviews the pathophysiology, etiology, and management of chronic respiratory failure in childhood.