HYPERBARIC APPLICATIONS FOR BRAIN INJURY
Hyperbaric Oxygen Therapy
What is HBOT?
HBOT is the use of OXTGEN at greater than atmospheric pressure as a DRUG to treat basic disease processes and their diseases. Like any drug, HBOT's effect are dose dependent, but unlike any other drug HBOT's effects span the widest range of species, physiology, and pathology.
How does HBOT work?
HBOT works by dissolving large amounts of oxygen in the liquid (plasma) portion of the blood where it exerts its drug-like actions. This process proceeds according to the one of the Universal Gas Laws, Henry's Law. Henry's Law says that the concentration of a gas in solution is proportional to the pressure of the gas interfacing with that solution. At sea level pressure nearly all of the hemoglobin in a human's blood is saturated with blood. As additional oxygen is supplied by nasal tubing or mask and then finally increasing pressure in an HBOT chamber the oxygen is dissolved in the plasma in increasing amounts. At 3 atmospheres absolute (ATA) of pressure, the equivalent pressure of 66 feet of seawater if one was SCUBA diving, there is enough oxygen in the plasma to completely supply the needs of the body without hemoglobin. In other words, at 3 ATA red blood cells is unnecessary. What are the effects of HBOT?
- Acute Effects: Acutely, HBOT is an extremely powerful drug at higher pressures. HBOT drives carbon monoxide out of the body and dissociates it from hemoglobin, oxygenates hypoxic tissue, compresses bubbles in decompression sickness, inhibits anaerobic bacteria (the flesh-eating bacteria), helps the body's immune system kill bacteria, reduces swelling in a number of diseases.
HBOT is the most effective drug for reperfusion injury: the injury that occurs to tissues that have been deprived of blood flow after the blood flow has been reestablished. The most common examples are the injuries of cardiac arrest, near-drowning, or asphyxia at birth. HBOT within one hour of these events has been shown to minimize or eliminate brain damage. This is one of the most exciting areas of hyperbaric medicine.
- Chronic Effects: In the setting of chronic wounds HBOT is most effective where the wound is characterized by a shallow gradient of decreased blood flow and oxygen. The best examples are the wounds of radiation injury and diabetic foot wounds. The repetitive exposure of these wounds to high levels of oxygen signals DNA in the cells of the low oxygenated tissue to transcribe wound repair sequences that control fibroblast replication, collagen deposition, angiogenesis, and epithelialization. These four processes are the necessary components of wound healing.
HBOT works in the brain just like it does in the rest of the body. In acute brain injury HBOT reverses hypoxia through Henry's Law, reduces swelling, and inhibits reperfusion injury. In chronic states HBOT acts on the shallow perfusion gradient wounds in the brain that are identical to other areas of the body. In addition, HBOT has a dramatic effect on energizing neurons that have been stunned by low blood flow and oxygen and are electrically paralyzed.
How does HBOT work in Cerebral Palsy and Pediatric Brain Disorders?
Pediatric brain disorders are an extremely heterogeneous mixture of disorders largely described by the appearance and function of the child. They are not defined primarily by the brain pathology since much of this is unknown. However, much of the pathology in cerebral disorders is the result of low blood flow, low oxygenation, and the stunning injury to the neurons described above. These abnormalities can be seen on brain blood flow imaging and often appear as shallow perfusion gradient wounds. As such they are responsive to the chronic effects of HBOT in C.2 (above). CP is a classic example of mostly ischemic/hypoxic injury and shallow perfusion gradients. Repetitive HBOT reestablishes blood flow to these damaged areas just like the chronic wounds of radiation injury and diabetes. With re-established blood flow and the re-energizing of the neuron function is restored.
What is the outcome of HBOT for Cerebral Palsy and Pediatric Brain Disorders?
HBOT best prepares brain-injured children for better outcomes with other therapies. Improvements are dependent on the severity and complexity of the injury. Studies have shown that many brain-injured children demonstrate movement and control improvements in the short term. This may include improved swallowing, breathing, cognitive function, or even body control, coordination, and reduced spasticity. In the intermediate term many children demonstrate further gains, as well as improved motor, and cognitive learning. These children often improve faster and demonstrate better gains with physical and other therapies in the intermediate term, as well as substantially better improvements in the long term.