Relationship between Changes in Cerebral Blood Volume During Hypoxic-ischemic Insult and Early Period after Insult

Abstract To achieve better outcomes in hypoxic-ischemic encephalopathy, categorizing the degree of the hypoxia-ischemia (HI) is important for selecting suitable candidates for therapeutic hypothermia and any additional treatment strategies. We previously developed a novel model of asphyxiated piglets with a uniform degree of histopathological brain injuries that survived for 5 days after insult and showed changes in cerebral blood volume (CBV) that reflected the severity of the brain injuries. However, little is known about the relationship between changes in CBV during and after insult. In this study, an HI event was induced by low inspired oxygen in 23 anesthetized newborn piglets, including three sham controls. CBV was measured using near-infrared time-resolved spectroscopy (TRS). Data were collected before, during, and 6 h after insult. The change in CBV was calculated as the difference between the peak CBV value during insult and the value at the end of insult. The decrease in CBV during insult was found to correlate with the increase in CBV within 6 h after insult. Heart rate exhibited a similar tendency to CBV but blood pressure did not. The CBV increment immediately after resuscitation provides a relatively precise prediction of the severity of HI insult.