One of the most common outcomes of brain damage resulting from oxygen deprivation during birth (perinatal or intrapartum asphyxia) is hypoxic-ischemic encephalopathy (HIE), sometimes referred to as neonatal encephalopathy (NE). HIE at birth can result in cerebral palsy, severe developmental or cognitive delays, or motor impairments as a child develops.
What is HIE?
HIE is best understood through breaking the term down.
Hypoxia is reduced oxygen supply to the brain, ischemia is low blood flow to the vital organs (including the brain), and encephalopathy refers to dysfunction of the brain. So, HIE refers to a brain dysfunction that is a result of reduced oxygen supply and blood flow to the brain. Neonatal Encephalopathy (NE) means a brain dysfunction in the neonate (newborn). HIE and NE generally occur from a brain injury in the perinatal period (leading up to and just after delivery).
While a baby’s body can cope with brief periods of depleted oxygen, if that lasts too long, brain injury can result. Asphyxia and HIE is a primary cause of death or severe impairment among infants.
When Does HIE Occur?
HIE is common in full-term babies but sometimes also occurs in premature infants. Resulting symptoms will vary depending on the timing and severity of the hypoxia.
If the lack of oxygen occurs before week 35 of development, HIE is likely to produce periventricular leukomalacia (PVL). The area of the brain that is affected will depend on the duration and severity of the hypoxia-ischemia. At week 40 and beyond, mild hypoxia will generally impact the parasagittal white matter and severe hypoxia will generally affect the putamen, thalamus, and paracentral white matter. Sometimes the entire brain is affected.
Every case is unique. The long-term effects that a child will experience as a result of HIE will depend on what area of the brain is impacted.
What Are the Symptoms of HIE?
Depending on the criteria, HIE can be identified through a variety of signs and symptoms, including:
- Low heart rate;
- Poor muscle tone;
- Bluish or pale skin colour;
- Excessive acid in blood;
- Meconium-stained amniotic fluid;
- Seizures within 24 hours of birth;
- Organ dysfunction.
If a birth was traumatic, or if significant risk factors for HIE (such as fetal stroke or a drop in the fetal heartrate) occurred during a pregnancy, HIE might be suspected at birth. This is sometimes referred to as a sentinel event. In other cases, parents and physicians may only notice signs of HIE over time.
Tests that can be used to further investigate HIE include:
- CT scan;
- MRI scan;
- Electrocardiogram (EKG); and
- Electroencephalogram (EEG).
Newer techniques, including diffusion-weighted imaging and MR spectroscopy, are also thought to be effective if used quickly enough.
However, it is important to remember that no single symptom or test is definitive in ruling out HIE or hypoxic brain injury. Sometimes an MRI or brain imaging can appear normal, but other evidence shows that the HIE and brain injury was caused by hypoxia-ischemia.
There are generally thought to be three types of HIE: mild, moderate, and severe. However, there are exceptions.
What Are the Effects of HIE?
The impact of HIE will vary, depending on the individual. In some cases, children with seemingly only mild symptoms will see a significant impact on their daily lives and future as adults. In more serious cases, children may suffer years of painful problems and have a shortened lifespan. Some effects of birth injury leading to HIE include:
- Cognitive issues;
- Delayed development;
- Impaired motor function; and
- Neurodevelopmental delays.
The severity of a brain injury is not always apparent until a child is three or four years old or even later in life. Effects may begin to present over time as a child misses important developmental milestones or sees a decline in learning at school compared to other children their age.
Risks Indicators for HIE
There can be a number of different causes of HIE, occurring either before, during, or after birth.
A variety of medical complications during pregnancy may increase risk factors for HIE (i.e. the antepartum period), including:
- Intrauterine growth restriction/small for gestational age;
- Maternal diabetes;
- Large for gestational age (macrosomia);
- Too much or too little amniotic fluid (Polyhydramnios or oligohydramnios);
- Cardiac disease;
- Lung malformations; and
- Fetal anemia.
Complications during labour and delivery (i.e. the intrapartum period) may also result in HIE, including:
- Very low maternal blood pressure;
- Umbilical cord accidents leading to cord compressions (like nuchal cord or a tangled cord);
- Abnormal fetal heart rate (bradycardia/tachycardia) and fetal distress;
- Too frequent contractions (tachysystole);
- Prolonged late stage labour;
- Placental insufficiency;
- Placental rupture or abruption;
- Abnormal fetal position; and
- Excessive bleeding from placenta.
Complications after delivery (i.e. the postpartum period) resulting in HIE include:
- Failed resuscitation;
- Very early prematurity;
- Brain or skull trauma;
- Severe cardiac or pulmonary disease;
- Infections (sepsis, meningitis, etc.); and
- Low neonatal blood pressure.
How is HIE Treated?
Physicians have various options to treat HIE, depending on the cause of the HIE and the amount of damage.
In cases of fetal distress or a high-risk birth, the neonatal team should always be called. If the baby is not breathing, a Code Pink or Code Blue should be called immediately on delivery. If a baby is delivered ‘flat’, with low APGAR scores or acidosis, there are a number of interventions that should be attempted, including
- A full resuscitation;
- Ventilation for babies who cannot breathe independently;
- Suction of meconium;
- Administration of sodium bicarbonate and epinephrine;
- Cooling the baby’s brain or body to slow the effects of hypoxia;
- Hyperbaric oxygen treatment where HIE is caused by carbon monoxide intoxication;
- General anesthesia and medication to control seizures;
- Maintenance of normal blood glucose and blood pressure; and
- Minimization of cerebral edema.
The baby will probably be admitted to a NICU (neonatal intensive care unit). If the baby is born in a small or rural hospital, the newborn might be airlifted to higher-level regional hospital. For example, in Ontario, many of the most seriously injured babies are brought in to the Level 3 Hospital in their region: London Health Sciences Centre, Hamilton Health Sciences – McMaster, The Hospital for Sick Children (HSC), Mount Sinai Hospital, Sunnybrook Health Sciences Centre, Children’s Hospital of Eastern Ontario, or The Ottawa Hospital.
Doctors and obstetricians must always be prepared for emergencies during childbirth, taking into account any risks and complications that may develop earlier in the pregnancy.
If you have questions about the medical care your baby received after birth, or if you suspect that something out of the ordinary or abnormal may have occurred, contact the respected and highly knowledgeable Toronto medical malpractice lawyers at Sommers Roth & Elmaleh. We have been involved in many precedent setting decisions and have a proven track record of success. Call us at 1-416-961-1212 or contact us online for a free consultation.
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