Brain Death

Online Noninvasive Assessment of Human Brain Death by Near-Infrared Spectroscopy with Protocol of O2 Inspiration

Brain death is the irreversible loss of all the functions of the brain and brainstem. Compared to traditional diagnostic methods of brain death, near-infrared spectroscopy (NIRS) is a noninvasive, objective, cost-effective, and safe way of assessment of brain death. Eighteen brain dead patients and 20 healthy subjects were studied by NIRS, with a multiple-phase protocol at varied fractions of inspired O₂ (FIO₂). We found that the changes in the concentration ratios of oxyhemoglobin to deoxyhemoglobin (Δ[HbO₂]/Δ[Hb]) in the cerebral cortex of brain dead patients were significantly higher than those of healthy subjects, and its low-to-high FIO₂ phase was most sensitive, with a recommended threshold in the range 1.40-1.50. Our study indicated that NIRS is a promising technology for assessing brain death. The success of this application potentially offers a supplementary technique for the assessment of brain death in real time in order to be able to promptly offer quality-assured donor organs.

Noninvasive and sensitive optical assessment of brain death

Brain death is an irreversible loss of all brain functions, and the assessment is crucial for organ supply for transplantation. The noninvasive, sensitive, universally available and timely ancillary method to assess brain death has not been established. Here, we attempted to explore a noninvasive way in brain death assessment. Eighteen brain-dead patients and 20 healthy subjects were measured by near-infrared spectroscopy (NIRS), with a multiple-phase protocol at varied fraction of inspired O₂ (FIO₂ ). We found that the concentration changes ratios of oxyhemoglobin to deoxyhemoglobin (Δ[HbO₂ ]/Δ[Hb]) in the cerebral cortex of brain-dead patients were significantly higher than those of healthy subjects. And, the Δ[HbO₂ ]/Δ[Hb] in low-to-high FIO₂ phase was most sensitive to distinguish brain-dead patients from healthy subjects, with a recommended threshold ranged in 1.40~1.50. The innovative incorporation of NIRS and a varied FIO₂ protocol was shown to be a noninvasive and reliable way in assessing brain death. This successful attempt of NIRS application is a help for fast and accurate evaluation of brain death, promptly offering quality-assured donor organs and indicate us a protocol-aided way to expand the use of NIRS.