Chapter

Oxygen Transport to Tissue XXXIII

Volume 737 of the series Advances in Experimental Medicine and Biology pp 103-109

Date:

The Confounding Effect of Systemic Physiology on the Hemodynamic Response in Newborns

  • B. B. ZimmermannAffiliated withAthinoula A. Martinos Center for Biomedical Imaging, Harvard Medical School, Massachusetts General HospitalBiomedical Optics Research Laboratory, Clinic for Neonatology, University Hospital Zürich Email author 
  • , N. Roche-LabarbeAffiliated withAthinoula A. Martinos Center for Biomedical Imaging, Harvard Medical School, Massachusetts General Hospital
  • , A. SurovaAffiliated withAthinoula A. Martinos Center for Biomedical Imaging, Harvard Medical School, Massachusetts General Hospital
  • , D. A. BoasAffiliated withAthinoula A. Martinos Center for Biomedical Imaging, Harvard Medical School, Massachusetts General Hospital
  • , M. WolfAffiliated withBiomedical Optics Research Laboratory, Clinic for Neonatology, University Hospital Zürich
  • , P. E. GrantAffiliated withNewborn Medicine and Radiology, Children’s Hospital of Boston
  • , M. A. FranceschiniAffiliated withAthinoula A. Martinos Center for Biomedical Imaging, Harvard Medical School, Massachusetts General Hospital

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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.