[OPTICAL REVIEW Vol. 10, No. 5 (2003) 466-469]
© 2003 The Optical Society of Japan

Measurement of Cerebral Optical Pathlength as a Function of Oxygenation Using Near-infrared Time-resolved Spectroscopy in a Piglet Model of Hypoxia

Takashi KUSAKA*, Yoshio HISAMATSU1, Kou KAWADA, Kensuke OKUBO1, Hitoshi OKADA1, Masanori NAMBA1, Tadashi IMAI1, Kenichi ISOBE1 and Susumu ITOH1

Maternal Perinatal Center, Kagawa Medical University, Mikicho 1750-1, Kitagun, Kagawa 761-0793, Japan
1Department of Pediatrics, Kagawa Medical University, Mikicho 1750-1, Kitagun, Kagawa 761-0793, Japan

(Received February 14, 2003; Accepted April 15, 2003)

Near-infrared spectroscopy (NIRS) has been used for measurement of changes in cerebral hemoglobin concentrations in neonates to study cerebral oxygenation and hemodynamics. In this study, measurements by time-resolved reflectance spectroscopy (TRS) were performed in a piglet model with various degrees of cerebral oxygenation to estimate the differential pathlength factor (DPF). A portable three-wavelength TRS system (TRS-10, Hamamatsu Photonics K.K.) with a probe attached to the head of a piglet was used. Eleven newborn piglets were anesthetized and respired by a ventilator to induce stepwise hypoxia loading. The DPF showed positive linear relationship with arterial hemoglobin (Hb) oxygen saturation and sagittal sinus venous Hb oxygen saturation at 761 and 795 nm. The DPF at 835 nm also showed very slight positive linear relationship with arterial hemoglobin oxygen saturation. The DPF values obtained in this study should contribute to a better understanding of noninvasive measurements by NIRS in neonates.

Key words: near-infrared spectroscopy, time-resolved reflectance spectroscopy, newborn piglets, differential pathlength factor, hypoxia, brain

*E-mail address: kusaka@kms.ac.jp

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