Data from several studies corroborate that a pH <7.0 is the threshold for clinically signiicant acidemia (Gilstrap, 1989; Goldaber, 1991). he likelihood of neonatal death grows as the cord artery pH falls to 7.0 or less. Casey and colleagues (2001) reported that when the pH was $6.8, the neonatal mortality rate rose 1400-fold. When the cord pH was $7.0 and the 5-minute Apgar score was 0 to 3, the risk of neonatal death was increased 3200-fold.
In the study from Oxford, adverse neurological outcomes were 0.36 percent with pH <7.1 and 3 percent with pH <7.0 (Yeh, 2012). As mentioned, newborn complication rates rise coincident with increasing severity of acidemia at birth. In a Swedish study, researchers observed that cord blood lactate levels may prove to be superior to base deicit for prognostication of neurological disorders (Wiberg, 2010).
Both immature red cells and lymphocytes enter the circulation of term newborns in response to hypoxia or hemorrhage. During the past two decades, quantification of these cells has been proposed as a measure of hypoxia, but most studies do not support this premise (Boskabadi, 2017; Silva, 2006; Walsh, 2011, 2013).
Various neuroimaging techniques have provided important insight into the etiology and evolution of perinatal HIE and later cerebral palsy (p. 621). Importantly, indings are highly dependent on fetal age. he preterm neonatal brain responds quite diferently to an ischemic episode compared with that of a term newborn. Other factors include insult severity and duration as well as restoration of cerebrovascular hypoperfusion. hus, precise timing of an injuy with neuroimaging studies is not a realistic goal. Moreover, the grade of neonatal encephalopathy, that is, mild, moderate, or severe, does not correlate with MR imaging indings (Walsh, 2017).
Regarding early use, the 2014 Task Force concluded that these imaging techniques provide the following information: 1. Sonographic studies are generally normal on the day of birth.
With injury, increasing echogenicity in the thalami and basal 2.0 2 (0.8-5.5) ganglia is seen beginning at approximately 24 hours. This progresses over 2 to 3 days and persists for 5 to 7 days.
CI = confidence interval.
2. Computed tomography scans are usually normal the first
Data from Moster, 2001 .
day in term infants. With injury, decreased density in the
Diseases and Injuries of the Term Newborn 625 thalami or basal ganglia is seen beginning at about 24 hours and persists for 5 to 7 days.
3. Magnetic resonance imaging will detect some abnormalities on the irst da. Within 24 hours, MR imaging may show restricted water difusion that peaks at approximately 5 days and disappears within 2 weeks. Acquisitions with Tl-and T2-weighted images show variable abnormalities, which have an onset from less than 24 hours to several days. In a study of 175 term neonates with acute encephalopathy, it was reported that MR imaging showing basal ganglia lesions accurately predicted motor impairment at 2 years of age (Martinez-Biarge, 2012).
he 2014 Task Force concluded that for term newborns, imaging studies are helpful in timing an injury, but they provide only a window in time that is imprecise. In one study, the optimal range was 3 to 10 days (Lee, 2017).
Neuroimaging in Older Children with Cerebral Palsy