Abnormalities in cerebral hemodynamics and changes with surgical intervention in neonates with congenital heart disease

Commentary: Near-infrared technology continues to evolve, but the holy grail remains elusive

“…Although it may be reassuring to find that our expectations regarding these findings are confirmed by the dual infrared technology of Cheng and colleagues, 1 it is important to recognize that this technology, and in fact all current near-infrared spectroscopic technology, is not measuring intracellular oxygenation status. It is telling us exactly the same information that we can derive if we know the arterial oxygen saturation of blood flowing to the brain and the mixed venous oxygen saturation of the blood that is coming from the brain.…”

“…The article by Cheng and colleagues 1 in this issue of the Journal reflects the ongoing development and increasing sophistication of noninvasive optical methods for determining cerebral blood flow and oxygenation status of the neonatal and infant brains. As fiberoptic technology was rapidly evolving in the 1970s and 1980s, Frans Jobsis at Duke pioneered the clinical application of near-infrared light to determine oxygenation status of organs, including the brain.…”

“…Jobsis also strove to measure a much more subtle index, the redox status of cytochrome a,a 3 , the terminal cytochrome of the intracellular electron transport chain. Since the early work of Jobsis, a number of academic and commercial groups have developed increasingly sophisticated methods, including the system applied in the study of Cheng and colleagues, 1 which uses frequency domain near-infrared spectroscopy. This instrument uses multiple infrared transmitters and detectors and multiple frequencies within the near-infrared spectrum.…”

“…This combination allows more accurate determination of path length and thus more accurate determinations of oxygenation status. The other technique that Cheng and colleagues 1 have applied is diffusion correlation spectroscopy, which is a variation on laser Doppler flowmetry. By observing the Doppler shift in frequency of a nearinfrared laser beam, inferences can be made regarding the blood flow within the interrogated volume of brain tissue.…”

“…By observing the Doppler shift in frequency of a nearinfrared laser beam, inferences can be made regarding the blood flow within the interrogated volume of brain tissue. The instrument that Cheng and colleagues 1 have used in this study is the result of ongoing work from the laboratory at the University of Pennsylvania of Britton Chance, who was also a pioneer in the early development of near-infrared spectroscopy. A small number of validation studies of diffusion correlation spectroscopy have been encouraging; however, there is little doubt that instruments for noninvasive assessment of cerebral oxygenation and cerebral blood flow will continue to evolve.…”