Medical Abbreviations: A Closer Look at HIE

Perinatal asphyxia occurs in both full-term and pre-term infants and is the pre-cursor to Hypoxic-Ischemic Encephalopathy. When an infant cannot initiate and sustain effective breathing after birth or when the placenta has malfunctioned before birth, oxygen and carbon dioxide cannot be adequately exchanged. This results in a dangerous drop in the infant’s blood oxygen level, an increase in the levels of carbon dioxide and also the accumulation of acid. If not quickly corrected, the heart will weaken and the heart rate slows down. This drop in heart rate causes a decrease in the amount of blood that reaches other organs in the body including the brain.

Hypoxic-Ischemic Encephalopathy (HIE) is characterized by clinical and laboratory evidence of acute or sub acute brain injury. If the degree of asphyxia is that of a degree that will cause long-term sequelae, the infant will display signs of neurological dysfunction shortly after birth. These signs include altered levels of consciousness, altered reactivity, altered muscle tone and seizures. One of the most widely used scales is the staging system developed by Sarnat and Sarnat. This staging system is divided into three categories; mild, moderate and severe.

The guidelines of the American Academy of Pediatrics (AAP) and the American College of Obstetrics and Gynecology (ACOG) state that all of the following must be present for the diagnosis of asphyxia:

• Profound metabolic or mixed academia (pH < 7.00) in an umbilical artery sample
• Persistence of an Apgar score of 0-3 for longer than 5 minutes
• Neonatal neurologic sequelae (seizures, coma, hypotonia)
• Multiple organ involvement (kidney, lungs, liver heart, intestines)

Infants who have a mild (stage I) degree of encephalopathy are noted to have periods of irritability that interchange with periods of “hyperalterness”. These infants are also noted to feed poorly, have inconsistent sleep-wake cycles, and are noted to appear “jittery”. Neonates who are diagnosed with a moderate (stage II) degree of encephalopathy demonstrate stupor, lethargy, hypotonia, hyporeflexia and seizures. Feeding is extremely poor. Muscle tone is decreased with a definite head lag. There is a marked decreased in spontaneous motor activities. Seizures may also be noted. Long-term effects are noted in 20 to 40 percent of these infants.

Infants who are diagnosed with severe encephalopathy (stage III) are unresponsive to noxious stimuli. Seizures are very common. These newborns often have heart rate drops, low blood pressure, and irregular breathing. If these infants recover there likely will be issues with abnormal swallowing and sucking movements. Often infants who have severe encephalopathy do not display those signs until two to three days after birth.

Since those infants who have hypoxic–ischemic encephalopathy due to asphyxia have multi-organ systems that require significant intervention initial care is supportive. Adequate ventilation is a priority and the amount of intervention needed can range from none to mechanical ventilation. Anticonvulsants are often used to treat seizure activity. It is important to note that those seizures which are associated with severe encephalopathy are difficult to control even with anticonvulsant medication.

Infants who are diagnosed with HIE have varying degrees of needs once discharged from the hospital. Some of those needs can include; tracheotomy, feeding assistance (nasogastric tube or G-tube), and anticonvulsant medication. Outpatient therapies often include; speech therapy (to initially help with feeding issues), occupational therapy and physical therapy. Outpatient physician follow-up will involve multiple specialties including; pediatrics, neurology and developmental specialists.

Parents of these children have many obstacles to face from the loss of anticipated wishes for a newborn child to the financial decisions that they have to make in taking care of a child with multiple medical and developmental needs.

Contact us for more information on HIE and its effects on the newborn who is diagnosed with it and the families whose lives are changed by this diagnosis. We can provide in- house educational presentations on this subject as well as neonatal seizures, developmental delays, feeding delays, perinatal asphyxia and intrauterine asphyxia.

References:
Acarregui, M.J. Neurological Disorders: Asphyxia Iowa Neonatology Handbook: Neurology. Retrieved April 2007 from http://www.uihealthcare.com/depts/med/pediatrics/

Hahn, J.S. (2002) Clinical Manifestations of Hypoxic-Ischemic Encephalopathy pp. 1-13.

Raju, T. Hypoxic- Ischemic Encephalopathy Retrieved April 2007 from http://www.emedicine.com/ped/topic149.htm

Simon, N.P. Developmental Follow-Up of Infants Experiencing Perinatal Asphyxia Retrieved April 2007 from http://www.pediatrics.emory.edu/neonatalogy/dpc

For more information on this issue please see Contact Us and see how our services can work for you.