Hypoxia is a word that means reduced supply of oxygen to body tissues, and the term “cerebral hypoxia” refers to reduction of oxygen supply to the brain, leaving the vitals neurons in the brain quickly susceptible to long-term damage or cell death. Anoxia means complete lack of oxygen to the tissues.
In the context of child birth, this type of brain damage to a baby can be catastrophic.
Depending upon the location of the oxygen-deprived tissues, and the length of time that passes before oxygenation is restored, various types of brain injuries can occur. They can be categorized in several ways. The most useful way for someone trying to understand an injury suffered by a friend or family member is through the classification by severity and location of injury. For brevity, at the moment it suffices to say that injury can be as mild as “diffuse cerebral hypoxia,” which refers to impairment of brain function, either moderate or mild, due to low oxygen levels in the blood. Oxygen is carried in the red blood cells, and oxygen saturation levels measure the amount of oxygen. When our red blood cells have made one trip through the body, not all of the oxygen is released. Therefore, we still have a short time, less than 5 minutes, before our bodies completely utilize all the oxygen stored in our arterial system. Oxygen saturation drops rapidly without intake of fresh oxygen.
The most severe category of injury is a massive cerebral infarction. An infarction refers to cell death, and cerebral infarction is the death of neurons in the brain. This type of injury occurs when oxygenation to the brain is completely disrupted for a short period of time, whether due to an internal event, like a blood clot, or to an external event, such as choking, or, in the event of a neonate, something as unfortunate as the umbilical cord wrapping itself around the neonate’s neck, and cutting off blood flow through the carotid arteries, the major blood supply to the brain.
During pregnancy, the oxygen level of the infant is dependent upon the placenta, which plays the role of the lungs for the fetus. While in utero, there are various events that may cause compromise of oxygen to the fetus. Some of these events in the months prior to childbirth are primarily those things that affect the mother’s circulatory system and hemoglobin levels. In trauma of any sort, the mother’s blood pressure may drop because of loss of blood. This compromises the baby’s oxygen supply, and this condition must be corrected immediately or the baby will suffer hypoxic brain damage.
Hemoglobin is the molecule on the red blood cell, which enables oxygen delivery. This is why the mother’s hemoglobin is routinely monitored during pre-natal care, and it is also why the mother is typically given an iron supplement, as iron is necessary in the process of formation of hemoglobin.
Other causes of impaired oxygen delivery in the prenatal period include things that affect the overall health of the fetus, including drug or alcohol abuse or maternal diabetes, which has the chronic effect of vascular disease in the microcirculation. If there is a problem with the position of the fetus within the womb, and circulation from the placenta to the fetus is compromised, then this will result in hypoxia in the uterus. The physician who is delivering prenatal care to the mother should anticipate all of these conditions. Ultrasounds are taken, approximation of size will reveal normal or abnormal signs, anemia in the mother must be corrected, and diabetes should be well controlled.
There are always situations in which the mother receives excellent prenatal care, but unfortunate events occur may go unnoticed or uncorrected. Mild oxygen deprivation may result in difficulty with learning and memory. More severe or long-lasting deprivation of sufficient supply of oxygen to the developing brain may result in severe cognitive problems and problems with motor coordination.
The perinatal period is usually a joyful one, but it is also fraught with potential for mishap. Although today labor and delivery usually goes smoothly, there are more than a few potentially dangerous moments surrounding childbirth.
The mother in labor is typically connected to a fetal monitor, which detects signs of fetal distress. If such signs are detected, the baby should be delivered by caesarean section, if necessary, and no time should be wasted. Fetal distress may result from problems with blood flow to the placenta during labor, or may result because of change of fetal position during the pre-birth period. Low blood pressure in the mother will prevent adequate delivery of oxygen to the fetus.
A prolonged labor, or a separate condition known as pre-eclampsia may result in fetal distress. Some signs of pre-eclampsia to watch for are a significant increase in blood pressure in the mother, coupled with headaches and findings in the urine specimen, All physicians should take pre-eclampsia seriously, and the only treatment is early delivery by caesarean section. If allowed to progress, pre-eclampsia will result in maternal seizures, during which time the blood flow to the placenta may be interrupted, The mother should be immediately placed upon her left side to allow better oxygen flow to the placenta, as preparations are quickly made for delivery.
While in labor, all mothers should be monitored for signs of both maternal problems and fetal distress.
During the delivery process itself, the blood supply to the fetus may become severely compromised by a breech position or a prolonged period in the birth canal. The obstetrician should deal with a prolapsed umbilical cord promptly, or, as noted previously, the baby’s blood supply will be interrupted through strangulation, and blood from the placenta, through the umbilical vein, will not be able to carry oxygen to the baby’s brain.
There is a potentially life-threatening complication of pregnancy, which can occur right up through labor, resulting in both a threat to the mother and to the child. The placenta can either bleed abnormally, or the mother may suffer an early separation of the placenta from the uterine wall. About 1% of women suffer some form of placental abruption, but if there is only a small separation, the mild abruption is usually not dangerous. Most abruption occurs during the last trimester of pregnancy, and some signs are vaginal bleeding and/or abdominal pain that is unrelenting. This should prompt an immediate search for a cause, utilizing ultrasound as a diagnostic aid. Depending upon when in the pregnancy the abruption occurs, and the amount of bleeding it causes, your physician may monitor you in the hospital, or you may have to be delivered right away, as there is a danger that the mother can “bleed out.” In some cases, a hysterectomy is needed to save the life of the mother after delivery.
In any of these cases where an early c-section may be necessary, the physician may give corticosteroids to hasten development of the child’s lungs. Prematurity is associated with underdevelopment of the lungs, and premature babies may require mechanical ventilation.
If your child is born with a hypoxic or anoxic brain injury, you can look back through the events of your pregnancy and delivery to try to understand how this may have occurred. While sometimes brain injury in the newborn due to hypoxia is an unpreventable but tragic occurrence, examining the events of your pregnancy and delivery may help you deal with your feelings of grief by trying to better understand what may have contributed to your child’s brain injury. This is not an exhaustive list of everything that can occur during pregnancy and delivery, but rather is meant to provide a starting point if you are looking for a preliminary understanding of hypoxic brain injury.
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