Brain Oxygen Deprivation: Risks and Timeframes

May I ask the doctor?

Hello, doctor: On the fifth day of the Lunar New Year, there was a tragic incident in Kaohsiung involving a four-month-old baby girl who allegedly choked on milk and died suddenly.
Could you please tell me how long it takes for the brain to become oxygen-deprived when the airway is obstructed? How long can the brain be deprived of oxygen before brain death occurs? Thank you!

Yan Yan, 20~29 year old female. Ask Date: 2017/02/01

Dr. Jiang Junyi reply Neurology

The nervous system is highly sensitive to hypoxia.
When the arterial blood oxygen partial pressure drops to 60 mmHg, there may be dysfunction in judgment and visual capabilities.
The primary reason for this is the disruption of energy metabolism in nerve cells.
If the partial pressure decreases to between 50 and 35 mmHg, color discrimination ability diminishes, and the visual field narrows.
When the arterial blood oxygen partial pressure falls to between 50 and 30 mmHg, severe impairment of cortical function occurs, manifesting as disorientation, motor incoordination, followed by consciousness disturbances, and potentially leading to coma and death.
Generally, the decline in oxygen partial pressure occurs rapidly over time, with potential damage occurring within 3 to 4 minutes, although individual variations exist.
In brain tissue, the cerebral cortex has a high demand for oxygen.
Some patients who experience brain hypoxic lesions due to cardiac arrest may suffer cognitive impairments even if resuscitated.
It is advisable to consult a neurologist to discuss issues such as brain death.
Wishing you good health, peace, and joy.

Reply Date: 2017/02/01

More Info

Understanding brain oxygen deprivation is crucial, especially in emergency situations like choking. When the airway is obstructed, the brain is deprived of oxygen, which can lead to severe consequences, including brain damage and potentially death.
The brain is highly sensitive to oxygen deprivation. It requires a continuous supply of oxygen to function properly. When the airway is blocked, oxygen cannot reach the brain, leading to a condition known as hypoxia. The timeframe for how long the brain can survive without oxygen varies, but generally, irreversible brain damage can begin to occur within 4 to 6 minutes of oxygen deprivation. After approximately 10 minutes without oxygen, the likelihood of brain death increases significantly.

In the case of choking, the duration of airway obstruction is critical. If a person is unable to breathe, the brain will start to suffer from lack of oxygen almost immediately. The first symptoms of hypoxia can include confusion, dizziness, and loss of consciousness. If the obstruction is not relieved quickly, the risk of permanent brain damage increases dramatically.

For infants, like the 4-month-old baby mentioned in your question, the situation is even more precarious. Their brains are still developing, and they have less physiological reserve to cope with oxygen deprivation. Therefore, even a short period of choking can have severe consequences. In infants, the brain can begin to suffer damage within just a few minutes of oxygen deprivation.

In emergency situations, it is vital to act quickly. If someone is choking, performing the Heimlich maneuver or back blows can help dislodge the obstruction and restore breathing. If the person becomes unresponsive, calling emergency services and starting CPR is essential.

In summary, the brain can begin to suffer irreversible damage within 4 to 6 minutes of oxygen deprivation due to choking. The risk of brain death increases significantly after about 10 minutes without oxygen. Immediate intervention is crucial to prevent long-term damage or death. If you suspect someone is choking, do not hesitate to act swiftly and seek emergency medical assistance.

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