Dov Apfel.



Birth Injury Information
Dov Apfel.
Newborn Conditions Associated with Asphyxia
 

Hypoxic-Ischemic Encephalopathy

The neurological condition of the newborn during the early neonatal (immediate after birth) period is important in determining the cause of the brain injury and in predicting its severity over the long term. The term hypoxic-ischemic encephalopathy (HIE) is a clinical diagnosis of impaired neurological function that is usually made by a neonatologist or pediatric neurologist after delivery. A frequent cause of HIE is fetal asphyxia. Many clinicians use the criteria in Sarnat HB, Sarnat MS. Neonatal encephalopathy following fetal distress. Arch Neurol 1976; 33:696-705 to grade the severity of a newborn's neurologic condition after birth.

What is the significance of Seizures?

Seizures often develop in infants who sustained severe birth asphyxia during the first 24 hours of life. Since seizures can exacerbate a pre-existing brain injury, it is imperative that appropriate and timely treatment be implemented. However, researchers do not know for sure whether seizures are the manifestation of a severe brain injury, or whether they cause additional injury. In any event, when evidence of early-onset neonatal seizures is combined with evidence of other neurologic abnormalities resulting in a diagnosis of HIE, a compelling argument can be made that the newborn sustained an acute hypoxic-ischemic brain in-sult.

The Importance of Blood Gas Studies

An analysis of the newborn's acid-base status, together with the results of subsequent blood gas studies, is important in creating a link between birth asphyxia and brain damage. The analysis of umbilical cord blood provides information about how the fetus responded to decreased or inadequate oxygen supply. The term "perinatal asphyxia" is frequently used by pediatricians and neonatologists to describe a brain injury caused by hypoxic and ischemic complications leading to blood gas abnormalities at the time of birth.

It is interesting to note that even though the American College of Obstetricians and Gynecologists suggests that the blood's pH should be less than 7.0, if it is going to be used as a factor establishing a link between birth asphyxia and neurologic injury, this narrow view is not widely supported by the literature. Many other studies confirm that birth asphyxia can cause brain damage even when umbilical cord arterial pH is greater than 7.0. nevertheless, it appears that infants with severe intrapartum asphyxia, quantified by an umbilical artery pH of less than 7.00, are more likely to develop permanent brain injuries.

The Importance of Neuroimaging Studies

Technological advances in CT scanning and magnetic resonance imaging (MRI) have opened new frontiers for establishing a link between asphyxia and hypoxic-ischemic brain injury. While some physicians continue to question whether cerebral palsy can be caused by birth asphyxia, many pediatric neuroradiologists acknowledge that brain damage can result from acute obstetrical emergencies causing total or near total oxygen deprivation, or as a result of partial, intermittent episodes of oxygen deprivation over longer periods of time. Imaging studies reveal different patterns of brain damage in infants suffering acute total asphyxia, as compared to prolonged partial asphyxia. Sometimes, the films can distinguish between hypoxia or ischemia that was acute and produced brain damage in a short period of time, (10 or 15 minutes), and a prolonged hypoxia or ischemia that was present for a longer period of time, (1 hour or longer), before it produced irreversible brain damage.

Each one of the imaging techniques has strengths and weaknesses. It is also important to know whether a particular imaging study was performed at the optimal time to pinpoint when the asphyxial brain damage may have occurred. It is common for clinicians to order cranial ultrasounds, blood gas tests, and EEG's to assess an asphyxiated newborn. Cerebral edema (swelling) often occurs after an asphyxial episode, and seizures can exacerbate the edema and prolong the period during which brain cells are vulnerable.

Remember!

The quality and timing of newborn care may affect the severity of the brain damage that was caused by birth asphyxia. The question that parents will have to consider in some cases is whether the newborn received timely and appropriate treatment to reduce the potential adverse effects of systemic and neurologic complications present immediately after birth, or developing shortly thereafter. Some of the goals thought to improve the neurologic outcome of a newborn include:

  • Maintaining normal blood glucose,
  • Maintaining normal blood pressure,
  • Preventing or controlling seizures, and
  • Preventing or minimizing cerebral edema

A question that often requires the assistance of a qualified expert in pediatric neurology and/or neonatology to answer is whether the brain cells that were compromised during the initial asphyxial episode were going to die regardless of how carefully and rapidly the newborn's complications were corrected. In other words, was the sequence of events that caused asphyxial brain damage continue to produce additional damage during the first few days of life, or did the failure to stabilize the infant and correct the blood gas abnormalities cause additional brain injury?

 
Dov Apfel   •   11513 Ridge Mist Terrace   •   Potomac, Maryland 20854
301-938-4902