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Nasal intermittent positive pressure ventilation (NIPPV) and nasal continuous positive airway pressure (NCPAP) have proven to be effective modes of noninvasive respiratory support in preterm infants. Although they are increasingly used in neonatal intensive care, their hemodynamic consequences have not been fully evaluated. The aim of this study was to investigate the hemodynamic changes between NIPPV and NCPAP in preterm infants.This prospective observational study enrolled clinically stable preterm infants requiring respiratory support received NCPAP and nonsynchronized NIPPV at 40/minute for 30 minutes each, in random order. Cardiac function and cerebral hemodynamics were assessed by ultrasonography after each study period. The patients continued the study ventilation during measurements.Twenty infants with a mean gestational age of 27 weeks (range, 25-32 weeks) and birth weight of 974 g were examined at a median postnatal age of 20 days (range, 9-28 days). There were no significant differences between the NCPAP and NIPPV groups in right (302 vs 292 mL/kg/min, respectively) and left ventricular output (310 vs 319 mL/kg/min, respectively), superior vena cava flow (103 vs 111 mL/kg/min, respectively), or anterior cerebral artery flow velocity.NIPPV did not have a significant effect on the hemodynamics of stable preterm infants. Future studies assessing the effect of NIPPV on circulation should focus on less stable and very preterm infants.

Intravenous mannitol (IV-M) is widely administered in the clinic to lower intracranial pressure in patients with brain trauma and stroke. However, intracarotid arterial mannitol (ICA-M) is known to potently open the blood-brain barrier (BBB) to serum protein tracers such as the Evans blue dye (EBD). In this study, we aimed to determine the potential effect of IV-M on BBB permeability to EBD and a small molecular tracer sodium fluorescein dye (NaF). Rats received intravenous EBD/NaF injections, and after a 30-min equilibration time, they received mannitol (20%, 0.5 g/kg) through either route of administration. At 90 min after the mannitol injection, the rats were perfused to rid their circulations of the tracers, and the tracers extravasated into the brain parenchyma were measured by photospectrometry. As expected, ICA-M considerably increased EBD extravasation into the rat forebrain regions, including the motor cortex (P=0.0069), the striatum (P=0.0097), and the hippocampus (P=0.0281; student's t-test). In marked contrast, IV-M exerted no effect on EBD extravasation into these forebrain regions. To increase the power of the IV-M study, we repeated the experiments in two independent trials of experiments (n=6-9/group/trial) and found the same result. Finally, consistent with no effect on EBD extravasation, IV-M had no effect on NaF extravasation into the rat forebrain. In conclusion, we report direct evidence that IV-M, at a dose used clinically, in contrast to the same dose of ICA-M, exerted no effect on BBB permeability to protein and small molecular tracers.

The development of the blood-brain barrier (BBB) against permeability to inert tracers, such as Evans blue dye (EBD), occurs quite early on at embryonic stages (before E13-E15), and the BBB remains resistant to EBD between E15 and early adulthood (P20-P30). Here, we aimed to examine the changes in EBD permeability at a later stage in development, specifically comparing young rats (P20) with adult rats (P86). We found markedly higher EBD extravasation into the forebrains of adult rats compared with those of the young rats (P=0.0132; Student's t-test). In contrast, there was no difference in EBD extravasation to the liver, suggesting no change in vascular permeability in peripheral tissues. Furthermore, EBD extravasation into the cerebellum was less prominent than that into the forebrain, suggesting that the disruption of the BBB was brain-region specific. In conclusion, we found a specific increase in EBD extravasation in the mature forebrain, and the protocol that we used may be a good template for studying developmental disruption of the BBB.

Implications: This report describes difficulties encountered in the airway management of six infants with concurrent vallecular cyst and laryngomalacia. It is hoped that our experience will assist others in the management of such patients.