The relationship of intracranial infrared light absorbance to fetal oxygenation. I: Methodology.
Current clinical methods for assessing fetal oxygenation in labor are indirect and remain somewhat imperfect. Since infrared light passes through the cranium and infrared light absorbance by tissues has been shown in adult animals to vary with oxygenation, monitoring of infrared light absorbance may serve as the basis for a new, more direct technique for the assessment of fetal condition. Described here is the application of infrared reflectance spectrophotometry to a fetal sheep model and the precision of the relationship between fetal arterial or venous PO2 and infrared light absorbance at selected wavelengths. A very strong, linear correlation (r = 0.915) was found between fetal arterial PO2 and intracranial infrared light absorbance according to an algorithm developed for selective monitoring of the state of hemoglobin oxygenation in tissue. With further development, this method holds promise for a more direct, noninvasive assessment of fetal condition in labor than is currently available.
D000042:Absorption; D000818:Animals; D001921:Brain / Q000098:blood supply / Q000378:metabolism*; D005260:Female; D005312:Fetal Blood / Q000378:metabolism*; D005323:Fetal Monitoring; D006454:Hemoglobins / Q000032:analysis; D007259:Infrared Rays; D007743:Labor, Obstetric; D010100:Oxygen / Q000097:blood*; D010101:Oxygen Consumption; D011247:Pregnancy; D012756:Sheep
D006454:Hemoglobins; D010100:Oxygen