Auditory stimuli mimicking ambient sounds drive temporal "delta-brushes" in premature infants.

In the premature infant, somatosensory and visual stimuli trigger an immature electroencephalographic (EEG) pattern, "delta-brushes," in the corresponding sensory cortical areas. Whether auditory stimuli evoke delta-brushes in the premature auditory cortex has not been reported. Here, responses to auditory stimuli were studied in 46 premature infants without neurologic risk aged 31 to 38 postmenstrual weeks (PMW) during routine EEG recording. Stimuli consisted of either low-volume technogenic "clicks" near the background noise level of the neonatal care unit, or a human voice at conversational sound level. Stimuli were administrated pseudo-randomly during quiet and active sleep. In another protocol, the cortical response to a composite stimulus ("click" and voice) was manually triggered during EEG hypoactive periods of quiet sleep. Cortical responses were analyzed by event detection, power frequency analysis and stimulus locked averaging. Before 34 PMW, both voice and "click" stimuli evoked cortical responses with similar frequency-power topographic characteristics, namely a temporal negative slow-wave and rapid oscillations similar to spontaneous delta-brushes. Responses to composite stimuli also showed a maximal frequency-power increase in temporal areas before 35 PMW. From 34 PMW the topography of responses in quiet sleep was different for "click" and voice stimuli: responses to "clicks" became diffuse but responses to voice remained limited to temporal areas. After the age of 35 PMW auditory evoked delta-brushes progressively disappeared and were replaced by a low amplitude response in the same location. Our data show that auditory stimuli mimicking ambient sounds efficiently evoke delta-brushes in temporal areas in the premature infant before 35 PMW. Along with findings in other sensory modalities (visual and somatosensory), these findings suggest that sensory driven delta-brushes represent a ubiquitous feature of the human sensory cortex during fetal stages and provide a potential test of functional cortical maturation during fetal development.

Use of parenteral lipid emulsions in French neonatal ICUs.

OBJECTIVE: To determine the types of parenteral lipid emulsions currently used for preterm infants, their mode of delivery, and the main disease conditions that are considered by neonatologists as contraindications. DESIGN: National survey using a questionnaire. SETTING: 155 neonatal departments in France. RESULTS: 100 (65%) neonatal departments participated in the survey. The most widely used lipid emulsion was the 20% soybean oil/coconut oil-based emulsion (68% of the units), followed by the soybean oil-based emulsion (28.5%) and the soybean oil/olive oil-based emulsion (3.5%). Peripheral venous access was considered to be a possible route for the infusion of lipid emulsions in only 58 (63.7%) of the units. In 80%-90% of the units, sepsis, hemodynamic failure, thrombocytopenia, disseminated intravascular coagulation, and hyperbilirubinemia were considered to be relative or absolute contraindications, whereas only hemodynamic failure, disseminated intravascular coagulation, and to a lesser extent sepsis were most often perceived as absolute contraindications. CONCLUSIONS: Neonatologists are somewhat reluctant to use parenteral lipids when only peripheral venous access is available, despite the low osmolarity of the emulsions. This may impair, at least temporarily, the adequate supply of energy and/or essential fatty acids in infants who do not have central venous access. This study also shows a large heterogeneity of responses with regard to the contraindications for parenteral lipids.

Parenteral nutrition objectives for very low birth weight infants: results of a national survey.

OBJECTIVES: The aim of the study was to evaluate parenteral nutrition objectives for very low birth weight (VLBW) infants in neonatal intensive care units (NICUs), and to compare nutritional protocol differences according to levels of care. MATERIALS AND METHODS: A national survey was conducted in France through a questionnaire sent to 296 French neonatal departments to determine each team leader's nutritional objectives for parenteral nutrition of VLBW infants. RESULTS: A total of 172 of the 296 French neonatal departments responded to the questionnaire. Protein administration was not started during the first day of life in half of the responding units. Furthermore, half of the units initiated protein administration with less than 1 g x kg(-1) x day(-1). The day of introduction of lipid emulsions varied considerably from one unit to another, but more than half of the units started the lipid emulsions after the third day of life. Twenty percent of the units reported a target energy intake of 100 kcal x kg(-1) x day(-1), whereas 14% reported a target intake above or equal to 130 kcal x kg(-1) x day(-1). CONCLUSIONS: In comparison with recent guidelines for parenteral nutrition for VLBW infants, the results indicate that the majority of the departments are familiar with target macronutrient and energy intakes, but the time of introduction and the rate of progression of macronutrients, particularly proteins and lipids, are frequently lower than those defined by the guidelines. The large-scale publication of new nutritional guidelines for the parenteral nutrition of neonates and preterm infants as well as regular, specific training in the parenteral nutrition of preterm infants are needed.