Abstract
In preterm newborns, evoked hemoglobin responses often show inversed patterns when compared to patterns observed in adults. We suspect that changes in hematocrit during the transition from fetal to adult hemoglobin and the consequent period of low hematocrit cause such an inversion. To test this assumption, we performed a longitudinal auditory functional study in six premature neonates with a total of 18 recording sessions. Using near-infrared spectroscopy (NIRS), we measured both local (de)oxy-hemoglobin changes during auditory stimulation with a continuous-wave (CW-NIRS) system and baseline absolute (de)oxy-hemoglobin concentrations with a frequency domain (FD-NIRS) system. Our results show that the inversion in the functional hemodynamic responses in infants correlates with the total hemoglobin concentration. These results suggest that the available hemoglobin supply during the low hematocrit period is not sufficient to overcome oxygen demand during functional activation.
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Acknowledgments
The authors thank all the families for their participation and the nurses, physicians, and staff in the Neonatal ICU, Special Care Nursery, Pediatric Neurology, and maternity units at the Massachusetts General Hospital. This work is supported by NIH grant R01 HD42908.
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Zimmermann, B.B. et al. (2012). The Confounding Effect of Systemic Physiology on the Hemodynamic Response in Newborns. In: Wolf, M., et al. Oxygen Transport to Tissue XXXIII. Advances in Experimental Medicine and Biology, vol 737. Springer, New York, NY. https://doi.org/10.1007/978-1-4614-1566-4_16
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DOI: https://doi.org/10.1007/978-1-4614-1566-4_16
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