Being unresponsive, also known as unconsciousness, is a serious medical condition that requires emergency care. Unresponsiveness means that a person is not awake and cannot respond to stimuli like touch or sound. There are many possible causes for unresponsiveness ranging from fainting to severe brain injury. Determining how long someone can survive while unresponsive depends on the underlying cause.
What are the levels of unresponsiveness?
Doctors often categorize unresponsive patients into levels based on their ability to respond to stimuli:
- Alert – fully awake and aware, can respond normally
- Voice – responds only to voice, difficulty opening eyes
- Pain – only responds to painful stimuli like pinch
- Unresponsive – no response to any stimuli
As patients descend through these levels, they have progressively worse outcomes. Being alert or responding to voice has a good prognosis. Responding only to pain indicates more severe injury and higher risk of death. Being completely unresponsive is an emergency requiring immediate medical care to prevent permanent damage or death.
What causes someone to become unresponsive?
There are many underlying medical conditions that can cause a person to become unresponsive. Common causes include:
- Fainting – Temporary loss of consciousness caused by a drop in blood pressure or flow to the brain. Vasovagal syncope is the most common type of fainting.
- Seizures – Abnormal electrical activity in the brain. Generalized seizures cause loss of consciousness and muscle stiffness.
- Toxic ingestions – Overdose of drugs, alcohol, or other toxins disrupts brain function.
- Low blood sugar – Not having enough glucose in the bloodstream starves the brain of energy.
- Stroke – Disruption of blood flow to part of the brain impairs function.
- Head trauma – Direct injury to the brain from concussion, bleeds, or swelling.
- Lack of oxygen – Interruption of oxygen delivery to the brain during cardiac arrest, drowning, or respiratory failure.
Rare causes include severe infections like meningitis, electrolyte imbalances, and some types of seizures. Identifying the cause of unresponsiveness is critical for properly treating the patient.
How long can someone survive without oxygen to the brain?
The brain is extremely sensitive to lack of oxygen. Brain cells start dying within 5 minutes without oxygen. After 10 minutes without oxygen, brain damage is likely to be severe and death can occur. However, the exact duration someone can survive without oxygen depends on multiple factors:
- Age – Children’s brains can withstand lack of oxygen longer than adult brains.
- Body temperature – Colder body temperature preserves brain cell function longer.
- Blood pressure – Higher blood pressure keeps some blood/oxygen flowing to the brain.
- Blood sugar – Normal blood sugar provides some additional energy to brain cells.
In ideal conditions such as cold body temperature and high blood pressure, some patients have survived over an hour without oxygen. But in most cases of cardiac arrest or respiratory failure, permanent brain damage and death occur within 15 minutes without oxygen.
Brain damage after lack of oxygen
The longer someone goes without oxygen to the brain, the higher the risk of permanent neurological damage. After revival, patients may experience:
- Coma – unresponsive state
- Vegetative state – awake but no cognition/awareness
- Memory loss
- Blindness
- Paralysis
- Speech impairments
- Personality changes
The severity of brain damage depends on how long the brain went without oxygen and what parts of the brain were affected. With immediate CPR and defibrillation, brain damage can sometimes be minimized.
How long can someone survive without water?
Humans depend on water to maintain adequate blood circulation and supply nutrients to tissues. However, the body can survive without water for 1-3 days on average. Timeframes range from:
- 1 day – Young and healthy people in cool environments
- 3 days – Average for healthy adults in normal temperatures
- 1 week – Possible survival time in exceptional circumstances
Signs of dehydration and shock begin after 12-24 hours without water. Survival past 3-4 days without water is unlikely unless in a cold environment that slows water loss.
Dehydration symptoms
Progressive dehydration symptoms from lack of water include:
- Thirst
- Dry lips and mouth
- Skin tenting – skin stays raised after pinched
- Sunken eyes
- Feeling dizzy upon standing
- Weakness and fatigue
- Low urine output – concentrated dark yellow urine
- Rapid breathing and heartbeat
- Confusion and disorientation
- Unconsciousness
Without intervention, these symptoms would progress to hypovolemic shock, organ failure, and eventual death. Seeking medical attention for dehydration is vital.
How long can someone survive without food?
Humans can survive remarkably long periods without any food intake. Starvation studies have shown survival is possible for:
- 30-40 days without food – with only water intake and resting
- 70+ days in exceptional cases in cool environments
Much depends on a person’s body fat percentage and water intake. The body begins burning fat stores and muscle tissue after 24-48 hours without calories from food.
Starvation effects on the body
As the body breaks down fat and protein, starvation symptoms emerge such as:
- Fatigue and weakness
- Irritability and confusion
- Rapid heart rate
- Reduced body temperature – hypothermia
- Swollen limbs – edema
- Stomach pains
- Skin rash
- Brittle hair and nails
- Organ failure
Death ultimately occurs from cardiac arrhythmias, seizures, or secondary infections. Getting medical care for malnutrition is vital before permanent organ damage occurs.
How long can someone be unconscious?
There is no fixed limit for how long someone can remain unconscious. Patients have awakened from comas lasting weeks or years in rare cases. However, the prognosis worsens the longer someone is unconscious. General guidelines include:
- Minutes to hours – Caused by fainting, seizures, or concussions. Full recovery is common.
- 2-4 days – Moderate injury with a chance of regaining consciousness and functional recovery.
- 1-2 weeks – Severe brain damage is likely with low chance of meaningful recovery.
- 4+ weeks – Individual may remain in vegetative state permanently.
Comatose patients require intensive medical care to prevent secondary complications like pneumonia, blood clots, and bed sores which worsen outcomes.
Assessing level of consciousness
Doctors use the Glasgow Coma Scale to assess impairment in patients who are unconscious or have altered mental states. It involves rating three parameters:
- Eye opening – scored from none to spontaneous
- Verbal response – scored from none to fully oriented
- Motor response – scored from none to obeying commands
Total scores range from 3-15. Scores under 8 indicate coma or severe brain injury. Repeat assessments determine if a patient is improving or worsening.
When to seek emergency help for unresponsiveness
Any episode of unresponsiveness or altered mental status lasting more than a minute or two constitutes a medical emergency. Immediate evaluation is needed to determine the cause and prevent permanent effects. Call emergency services or go to an emergency room right away if someone:
- Is unconscious or semi-conscious
- Cannot be woken or stimulated
- Is rigid, shaking, or having seizure-like activity
- Has slow, irregular, difficult breathing
- Has skin that is cold, pale, or changed color
While waiting for help:
- Check airway for blockages
- Begin CPR if no breathing
- Avoid moving the person if trauma is suspected
Prolonged unconsciousness or unresponsiveness should be considered a life-threatening emergency until proven otherwise.
Conclusion
The duration someone can remain unconscious, survive without oxygen, water, or food varies based on many medical factors. In general, permanent damage and fatalities quickly ensue beyond several minutes without oxygen, a few days without water, or a month without food. Those experiencing any level of unresponsiveness or altered mental status should seek emergency medical care to determine the cause and initiate lifesaving treatment promptly.