Traumatic Brain Injury vs. Anoxic Brain Injury:
In recent years there has been increased publicity on traumatic brain injuries (TBI) caused by concussion or blows to the head, as in the case of football players. Another type of brain injury is called anoxic brain injury which occurs when the brain does not receive sufficient oxygen. This devastating injury can result any time a human is deprived of taking in oxygen into the body and ultimately into the blood which supplies the brain. It can occur as a result of asphyxiation from a number of causes including brain injury to the fetus as result of complications during child birth, drowning, prolonged exposure to carbon monoxide, stroke and medical errors involving use of anesthesia.
By definition, anoxia means without oxygen; the term is often used in conjunction with the term hypoxemia. In fact, the two conditions are distinct but nevertheless involve insufficient oxygenation of the blood which results in injury and death to brain cells and usually a corresponding loss of function. Cerebral anoxia occurs when the brain is completely deprived of oxygen. There are four categories of cerebral hypoxia, the most severe being (1) diffuse cerebral hypoxia followed by (2) focal cerebral ischemia, (4) cerebral infarction and (4) global cerebral ischemia. Prolonged hypoxia induces cell death resulting in hypoxic brain injury. Generally speaking, the greater the loss of oxygen, the bigger the injury to the brain.
Anoxic brain injuries can be caused by internal or external events. A stroke or cardiac arrest is a common example of an internal cause. External causes include asphyxia (drowning or suicide), chest trauma, electrocution, severe bronchial asthma, poisoning, and anesthesia accidents. Anesthesia accidents make up approximately one third (1/3) of such injuries.
In the context of medical procedures where a patient has been placed under anesthesia, the individual is already compromised medically and the physiologic brain injury due to a lack of oxygenation can occur rather quickly. This is why it is extremely important during medical procedures where anesthesia will be administered that the patient be made aware of the risks associated with anesthesia and be fully informed prior to accepting the risks inherent with receiving anesthesia. It is extraordinarily important that anesthesiologists be present and/or ensure that the vital signs of the patient can be continually monitored for the signs and symptoms of hypoxemia.
The degrees of injury and loss of cognitive and behavioral function will vary depending upon the severity of the insult to the brain. Some individuals may be able to function at a relatively high level with assistance. Others may become completely dependent upon caregivers for all activities of daily living. If the anoxia/hypoxemia is allowed to persist it can result in death. In many cases the length of time required to cause permanent injury is related to the amount of oxygen deprivation together with the underlying health of the individual suffering the loss of oxygenation.