Brain Hypoxia And Oxygenation, Prevention And, Treatment!
Lack of Oxygen, Hypoxia, And Oxygenation:
Hypoxia is a very common condition with mountain climbers and a pilot’s experience. Essentially what hypoxia is that at certain altitudes the body doesn’t get enough oxygen. In particular, during hypoxia certain tissues in the body do not get any oxygen, and as such severe health concerns and consequences result. Mountain climbers are individuals that love their sport. They can’t wait until the next time that they can go and hit the mountains. hypoxia
However, their love for the sport also comes with some serious health risks and concerns. In particular, the mountain climbers are operating at extremely high altitudes and thus the oxygen levels are very low.
As Such,
They are they need to particularly pay attention to their blood oxygen saturation to ensure that they are not at the risk of hypoxia. Blood oxygen saturation is determined as the percentage of oxygen in the hemoglobin. When these levels of blood oxygen saturation fall below certain healthy norms then you are at risk of hypoxia.
The Same Issue Exists For Pilots.
Pilots, whether it’s for commercial purposes, hobby purposes, or military purposes, operate at extremely high altitudes and actually at varying altitudes. As a result, they need to ensure that they are monitoring their Blood oxygen saturation or SpO2 levels constant to make that they don’t run the risk of experiencing hypoxia.
A device that has proven to be a great tool for both mountain climbers, pilots, or any other person that operates at high altitudes is the use of a portable pulse oximeter.
What is Hypoxia?
Hypoxia is a serious threat to patients and escorts alike when they fly. Air medical escorts need to understand what causes hypoxia, why some people are more likely to become hypoxic as well as the signs and symptoms of hypoxia. This knowledge will enable air medical escorts to take steps to prevent hypoxia and to treat it if it does occur.
Hypoxia occurs when there is not enough oxygen getting to the brain. The brain needs a constant supply of oxygen and nutrients to function. Hypoxia affects the largest parts of the brain, called the cerebral hemispheres. However, the term is often used to refer to a lack of oxygen supply to the entire brain.
Types of Hypoxia Definition:
Hypoxia is an insufficient supply of oxygen to meet the demands of the body.
There are four basic types of hypoxia:
1. Hypoxic Hypoxia:
Hypoxic Hypoxia occurs when there is a deficiency in oxygen exchange in the lungs.
Some causes include:
- The decreased partial pressure of oxygen available at altitude.
- Conditions that block the exchange at the alveolar-capillary level (e.g. pneumonia, pulmonary edema, asthma, drowning).
2. Anemic (hyperemic) hypoxia:
Anemic (hyperemic) hypoxia occurs when the body cannot transport the available oxygen to the target tissues.
Causes include:
- Anemia from acute or chronic blood loss.
- Carbon monoxide poisoning.
- Medications such as aspirin, sulfonamides, and nitrites.
- Methemoglobinemia.
- Sickle cell disease.
3. Stagnant Hypoxia:
Stagnant hypoxia occurs when there is insufficient blood flow,
Causes include:
- Heart failure.
- Decreased circulating blood volume.
- Vasodilatation.
- Venous pooling due to G-forces.
- Continuous positive pressure ventilation.
- G-forces.
4. Histotoxic (Histologic):
Histotoxic (histologic) hypoxia occurs when the body’s tissues are not able to use the oxygen that has been delivered to them. This is not a “true hypoxia” because the tissue oxygenation levels may be at or above normal.
Causes include:
- Cyanide poisoning.
- Alcohol consumption.
- Narcotics.
Whatever the cause or causes of a patient’s hypoxia, it is important to recognize the potential for, and symptoms of, hypoxia early.
Causes of Hypoxia:
Everyone becomes hypoxic to some degree when exposed to decreased partial pressures of oxygen at altitude. Some factors beyond atmospheric pressure can cause some people to react as they would at altitude even when they are at sea level. These are what create a person’s physiologic altitude.
The following factors affect physiologic altitude.
- In cerebral hypoxia, sometimes only the oxygen supply is interrupted. This can be caused by:
- Breathing in smoke (smoke inhalation), such as during a fire.
- Carbon monoxide poisoning.
- Choking.
- Diseases that prevent movement (paralysis) of the breathing muscles, such as amyotrophic lateral sclerosis (ALS).
- High altitudes.
- Pressure on (compression) the windpipe (trachea).
- Strangulation.
In other cases, both oxygen and nutrient supply are stopped, caused by:
- Cardiac arrest (when the heart stops pumping).
- Cardiac arrhythmia (heart rhythm problems).
- Complications of general anesthesia.
- Drowning.
- Drug overdose.
- Injuries to a newborn that occurred before, during, or soon after birth, such as cerebral palsy
- Stroke.
- Very low blood pressure.
Brain cells are very sensitive to a lack of oxygen. Some brain cells start dying less than 5 minutes after their oxygen supply disappears. As a result, brain hypoxia can rapidly cause severe brain damage or death.
The following factors also can affect the body’s response to changes in altitude.
- Medications, such as aspirin, nitrites, and sulfa.
- Chronic Obstructive Pulmonary Disease (COPD).
- Diet.
- Level of physical fitness.
- Emotional state.
- Baseline metabolic rate.
- Fever or low body temperature (higher temperature tends to lower hemoglobin (Hgb) O2 saturation).
- High or Low pH:
-
- A. Low pH makes it harder for the hemoglobin to bind to oxygen (requiring a higher partial pressure to achieve the same oxygen saturation), but it makes it easier for the hemoglobin to release bound oxygen.
-
- B. High pH makes it easier for the hemoglobin to pick up oxygen but harder for it to release it to the tissues.
- Duration of exposure to altitude-the the longer the exposure, the more profound the effect.
- Change in altitude—the greater the change in altitude, the greater the effect.
The sum of a person’s actual altitude, his or her physiological altitude, along with the duration of exposure and the degree of change in altitude help determine how each person will react during air medical transport flights.
Signs And Symptoms:
The most common hypoxia symptoms are:
- Slow heart rate.
- Changes in the color of your skin, ranging from blue to cherry red.
- Sweating.
- A cough.
- Fast heart rate.
- Wheezing.
- Shortness of breath.
- Confusion.
- Rapid breathing.
Another symptoms of mild cerebral hypoxia include:
- Change in attention (inattentiveness).
- Poor judgment.
- Uncoordinated movement.
Symptoms of severe cerebral hypoxia include:
- Complete unawareness and unresponsiveness (coma).
- No breathing.
- No response of the pupils of the eye to light.
Stages of Hypoxia:
There are four stages of hypoxia. The amount of time spent in any one of these four stages may vary, and each patient and provider is likely to respond differently to the same conditions. The air medical escort needs to be alert to the signs and symptoms of hypoxia.
There are four stages of hypoxia:
1. Asymptomatic or Indifferent:
- People are not generally aware of the effects of hypoxia at this stage.
- The primary symptoms are a loss of night vision and a loss of color vision.
- These changes can occur at relatively modest altitudes (as low as 4,000 feet) and are probably most significant to pilots operating at night.
- Arterial oxygen saturations are typically between 90 and 95 percent.
2. Compensatory:
In healthy people, this stage may occur at altitudes between 10,000 and 15,000 feet. The body generally has the ability to stave off further effects of hypoxia by increasing the rate and depth of ventilation and cardiac output. Arterial oxygen saturation during this phase is typically between 80 and 90 percent.
3. Deterioration or Disturbance:
- In this state, people are unable to compensate for the lack of oxygen.
- Unfortunately, not everyone recognizes or experiences the signs and symptoms associated with this stage.
- If they do not, they cannot take steps to correct the problem.
The list below shows the signs that are associated with this stage:
- Shortness of breath-air hunger.
- Cyanosis.
- Drowsiness.
- Headache.
- Euphoria.
- Aggression.
- Poor Judgement.
- Incoordination.
- Difficulty with simple tasks.
- Diminished vision.
- Tingling.
- Numbness.
- Hot-cold flashes.
- Arterial oxygen saturation during this phase typically is between 70 and 80 percent.
4. Critical:
- This is the terminal stage leading up to death.
- People are almost completely incapacitated physically and mentally.
- People in this stage will lose consciousness, have convulsions, stop breathing, and finally die.
- Arterial oxygen saturations are less than 70 percent.
Diagnosis:
Exams and Tests:
Cerebral hypoxia can usually be diagnosed based on the person’s medical history and a physical exam. Tests are done to determine the cause of the hypoxia, and may include:
- Angiogram of the brain.
- Blood tests, including arterial blood gases and blood chemical levels.
- CT scan of the head.
- Echocardiogram, which uses ultrasound to view the heart.
- Electrocardiogram (ECG), a measurement of the heart’s electrical activity.
- Electroencephalogram (EEG), a test of brain waves that can identify seizures and show how well brain cells work.
- Evoked potentials, a test that determines whether certain sensations, such as vision and touch, reach the brain.
- Magnetic resonance imaging (MRI) of the head.
If only blood pressure and heart function remain, the brain may be completely dead.
Prevention and Treatment:
Prevention depends on the specific cause of hypoxia. Unfortunately, hypoxia is usually unexpected. This makes the condition somewhat difficult to prevent. Cardiopulmonary resuscitation (CPR) can be lifesaving, especially when it is started right away.
The prevention and treatment of hypoxia in the airborne environment can be accomplished in two ways:
- Provide sufficient oxygen.
- Fly at a lower altitude.
Unfortunately,
- It is not always possible to do both. Pilots must fly aircraft at safe altitudes for terrain and weather.
- Air medical escorts should communicate with pilots prior to and during flights about the effects of elevation.
- They should be prepared to ask the pilot to fly lower if needed.
- Air medical escorts should provide adequate amounts of oxygen to prevent their patients from deteriorating when flying at any altitude.
When patients are on oxygen before a flight, it can be challenging to determine their increased oxygen needs resulting from the additional stress of altitude and flight.
To increase the oxygen levels in your blood, your doctor may recommend:
- Deep breathing exercises
- Mild exercises such as walking or yoga
- Eating a healthy diet
- Drinking plenty of water
- Quitting smoking
How Do Doctors Treat Hypoxemia?
Cerebral hypoxia is an emergency condition that needs to be treated right away. The sooner the oxygen supply is restored to the brain, the lower the risk for severe brain damage and death.
Treatment depends on the cause of the hypoxia. Basic life support is most important. Treatment involves:
- Breathing assistance (mechanical ventilation) and oxygen.
- Controlling the heart rate and rhythm.
- Fluids, blood products, or medicines to raise blood pressure if it is low.
- Medicines or general anesthetics to calm seizures.
Sometimes a person with cerebral hypoxia is cooled to slow down the activity of the brain cells and decrease their need for oxygen. However, the benefit of this treatment has not been firmly established.
Treatment for hypoxemia aims to raise the levels of oxygen in the blood. Doctors can use medications to treat underlying conditions that cause hypoxemia. These medications are often given through an inhaler that enables you to breathe the medicine into your lungs.
- In more severe cases, your doctor may prescribe oxygen therapy.
- People typically receive extra oxygen through a device called a cannula (tube) that is clipped to the outside of the nose, or through a breathing mask.
- The location and amount of time people receive oxygen therapy is based on individual needs.
- You may receive oxygen at home, with a portable machine while you travel, or in the hospital.
Monitoring Oxygen Levels:
Pulse oximeters are the most common device for monitoring patients’ oxygen status. While a useful tool, pulse oximeters are not a replacement for arterial blood gas or for looking at the patient. They simply measure the saturation of the hemoglobin present in the blood, not the actual amount of oxygen in the blood.
Pulse Oximeters,
- Cannot differentiate which gas is bound to the hemoglobin, so readings are falsely elevated in carbon monoxide poisoning.
- Low flow states (shock), cold, and bright light can also make the readings unreliable.
- Portable blood gas analyzers are available, but the cost, the need for CLIA certification, training, and support limit the availability of these devices.
How Much Oxygen is Enough?
The following table is a guide to assist air medical escorts in determining their patients’ oxygen needs. The chart shows the oxygen concentration needed to maintain oxygen saturation at different altitudes. If a patient is on a given amount of oxygen at sea level (column marked SL), the flow rate to keep saturation levels above 90 percent at 10,000 feet can be found on the same row in the column labeled “10.
” Generally, it is advisable to keep oxygen saturations above 90 percent in patients who do not have COPD.
Altitude x 1,000 feet |
|||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
The fraction of Inspired Oxygen (FIO2) |
SL |
2 |
4 |
6 |
8 |
10 |
12 |
14 |
16 |
18 |
20 |
|
.21 |
.23 |
.24 |
.27 |
.29 |
.31 |
.34 |
.37 |
.41 |
.45 |
.49 |
|
|
.30 |
.32 |
.35 |
.38 |
.41 |
.45 |
.49 |
.53 |
.59 |
.64 |
.71 |
|
|
.40 |
.43 |
.47 |
.51 |
.55 |
.60 |
.65 |
.71 |
.78 |
.85 |
.94 |
|
|
.50 |
.54 |
.58 |
.63 |
.69 |
.75 |
.81 |
.89 |
.98 |
|||
|
.60 |
.65 |
.70 |
.76 |
.83 |
.89 |
.98 |
|||||
|
.70 |
.76 |
.82 |
.89 |
.96 |
|||||||
|
.80 |
.86 |
.94 |
|||||||||
|
.90 |
.97 |
||||||||||
|
1.00 |
|||||||||||
The table has empty spaces at certain FIO2/altitude combinations. Above these altitudes, patients cannot be saturated with oxygen.
In General,
Oxygen toxicity is not a problem for most patients (even neonates) for at least 24 hours.
This means that:
- Hypoxic or decompensated patients should not have oxygen withheld from them.
- Chronic obstructive pulmonary disease (COPD) patients who are hypoxic and decompensating need oxygen.
- Escorts should attempt to keep COPD patients at their “normal” oxygen saturation.
Complications of Hypoxemia:
If your blood does not have enough oxygen, it cannot deliver enough oxygen to the organs and tissues that need it. This situation can be fatal if severe in the short term and can affect the heart or brain if it persists over a long period of time.
Lack of Oxygen Causing Damage to Vital Organs:
Susceptibility to hypoxia varies between tissues. For example, the brain is very susceptible to a lack of oxygen, and death can result within just a few minutes if the brain does not get this oxygen to carry out aerobic metabolism.
However, the skeletal muscle in an arm or leg can undergo anaerobic metabolism (not requiring oxygen) for several minutes or longer (depending on the person’s training) before any harmful effects are noticeable.
Now, Let’s explain the issues that are most susceptible to a lack of oxygen (or hypoxia). This includes watershed areas, subendocardial tissue, and renal cortex-medulla.
1. Watershed Areas:
The Watershed areas are areas between two blood vessels (thus the name watershed). Examples of watershed areas include the tissue supplied by both the anterior and middle cerebral arteries (the area of the brain between these two arteries).
Another example is an area near the spleen (specifically, the splenic flexure of the intestines) that is supplied by the superior and inferior mesenteric arteries.
2. Subendocardial Tissue:
- Subendocardial tissue (from the heart) is also susceptible to hypoxia.
- This area is supplied by coronary arteries that go through the epicardial surface to reach subendocardial tissue.
- Patients with coronary artery disease may have symptoms of chest pain when under stress (such as exercise).
3. The Renal Cortex-Medulla:
Lastly, certain parts of the kidney (renal cortex and medulla) are also very susceptible to a lack of oxygen. Proximal tubule (straight portion) is the most susceptible and in the renal medulla (thick ascending limb) is also very susceptible.
Because of the increase in tissue susceptibility, hypoxia can cause damage to these vital organs (the brain, the heart, and the kidney). In summary, brain damage occurs in strokes, heart attacks result in irreversible heart damage, and kidney failure can result from infarcts in the arteries that supply blood to the kidney (renal artery).
Brain Hypoxia:
Brain hypoxia is when the brain isn’t getting enough oxygen. This can occur when someone is drowning, choking, suffocating, or cardiac arrest. Brain injury, stroke, and carbon monoxide poisoning are other possible causes of brain hypoxia. The condition can be serious because brain cells need an uninterrupted flow of oxygen to function properly.
There’re,
Many medical conditions and events that interrupt the flow of oxygen to your brain. Stroke, cardiac arrest, and an irregular heartbeat can prevent oxygen and nutrients from traveling to the brain.
- Cardiac or respiratory arrest.
- Irregular heart rhythm or poor function of heart muscle after a heart attack.
- Very low blood pressure resulting from the loss of blood or disturbed heart function.
- Suffocation.
- Choking.
- Strangulation.
- A very severe asthma attack.
- very severe allergic reaction causing the body to experience an anaphylactic.
- shock.
- Complications of administering general anesthesia.
- Near drowning.
- Exposure to high altitudes.
- Smoke inhalation.
- Carbon monoxide inhalation.
- Poisoning.
- Drug overdose.
- Electric shock.
Brain hypoxia requires immediate treatment to restore the flow of oxygen to your brain. You can prevent brain hypoxia by monitoring certain health conditions. See a doctor if your blood pressure is too low, and keep your inhaler nearby at all times if you are asthmatic. Avoid high altitudes if you are susceptible to altitude sickness.
Ways to Get more Oxygen to The Brain:
Lack of oxygen in the brain is not something the average person can recognize. However, it can cause poor brain function and increase the risk of vascular dementia, the second most common form of dementia after Alzheimer’s. The brain can be hungry for oxygen years or decades before dementia sets in. Risk factors include high or low blood pressure, heart disease, diabetes, smoking, alcoholism, and high cholesterol.
In Fact:
- The brain uses about three times as much oxygen as muscles in the body do.
- Brain cells are very sensitive to decreases in oxygen levels and don’t survive or function well very long without it.
- The brain is made up of very special cells called neurons, and each of them can do the job of any of the other neurons in the brain. That process gives us the ability to relearn most functions using different parts of the brain.
When we breathe heavier or deeper (more than the norm),
We remove too much carbon dioxide (CO2) from all cells of the human organism. This causes reduced blood flow to the brain. CO2 deficiency causes constriction of blood vessels (arteries and arterioles) and our brains get less blood supply. So instead of breathing big breaths to get more oxygen to your brain, here are three ways to do it:
1. Take short walks throughout the day:
- It’s not necessary to commit to a lengthy exercise session to reap the benefits of walking.
- Taking short walks will also help increase the blood flow to your brain.
- Even a walk of three to five minutes will have a positive effect on your blood’s circulation.
- Use a timer throughout your day to remind yourself to take walking breaks.
- If you work at a desk, schedule short walks.
- Take advantage of naturally occurring opportunities to walk. Take the stairs instead of the elevator.
- Park at a distance from your destination.
- Get off the bus or train before your exit, and walk the remainder of the route.
2. Breathe through your nose:
- Engage your diaphragm, in your abdominal area.
- This is also called “belly breathing.” Breathing deeply moves the air and oxygen down into the lower areas of the lungs where most of the circulation of blood is.
- the upper part of the lungs. Breathing through the mouth will lessen the exposure to freshly oxygenated air.
- Breathing with the diaphragm results in more oxygen entering this blood.
3. Stand Up:
Stand up on both feet or just one foot. A study found that standing with both feet together enhanced circulation in the anterior lobe and the right visual cortex in the brain. Standing on one foot increased circulation in the cerebellar anterior vermis and posterior lobe lateral cortex ipsilateral portions of the brain. Standing in tandem increased circulation in the visual association cortex, midbrain, anterior, and posterior vermis parts of the brain.
Summing Up:
The recognition, prevention, and treatment of hypoxia require an understanding of the pathophysiology that leads to hypoxia, the signs, and symptoms of the condition, and the methods of preventing and treating it.
Contact your doctor if you experience symptoms of hypoxemia. Early diagnosis and treatment can help ensure the condition does not get worse and cause dangerous complications.
If you find this article useful, don’t forget to share it with your friends and family, as you might help someone in need. Thanks.
Disclaimer: “Nothing in this article makes any claim to offer cures or treatment of any disease or illness. If you are sick please consult with your doctor.”
