iCliniq logo

Ask a Doctor Online Now

HomeHealth articleshypoxiaWhat Is Hypoxia?

Hypoxia- Clinical Presentation, Types, and Management

Verified dataVerified data

4 min read


Hypoxia is a condition that lacks oxygen at the tissue level and requires immediate medical attention. Read the article below to know more.

Medically reviewed by

Dr. Arpit Varshney

Published At January 2, 2023
Reviewed AtJune 16, 2023


Hypoxia is defined as a condition in which there is an absence of oxygen at the tissue level. Lung tissues take the oxygen from the inhaled air and combine it with the hemoglobin in the blood. Hemoglobin is an oxygen-binding protein that supplies oxygen to different body parts. Hypoxia and hypoxemia are often confused with one another. Hypoxia is a lack of oxygen at the tissue level, whereas hypoxemia is a lack of oxygen in the blood flow.

What Is the Clinical Presentation of Hypoxia?

Clinical presentation of hypoxia includes

  • Confusion.

  • Headache.

  • Slurred speech.

  • Fatigue or tiredness.

  • Hot flashes.

  • Lack of coordination.

  • Dizziness.

  • Shortness of breath or dyspnea.

  • An increase in the heart rate or tachycardia. Occurs as a result of compensatory mechanisms to pump more blood to the oxygen-deprived tissues.

  • Increase in the rate of breathing per minute or tachypnea.

  • Tunneling vision.

  • Cyanosis or bluish coloration of the skin and mucous membranes are especially found in nails, earlobes, and the tongue.

  • Palpitations.

  • Arrhythmias or abnormal heart rhythm.

  • Tingling sensation.

What Are the Types of Hypoxia?

Based on the mechanism of occurrence, there are various types of hypoxia:

  • Hypoxic hypoxia

  • Anemic hypoxia.

  • Stagnant hypoxia.

  • Histotoxic hypoxia.

Hypoxic Hypoxia:

It is the most common type of hypoxia. It is also known as true hypoxia. It is seen when there is a lack of oxygenation of blood in the lungs, which results in low partial pressure of oxygen in the arterial blood. So, a reduced amount of hemoglobin and central cyanosis develops when it exceeds 5 gm %. The peripheral chemoreceptors are stimulated.

Causes of hypoxia include

  • High altitude.

  • Ventilation-perfusion mismatch. Lungs need both airflow (ventilation) and blood flow (perfusion), and whenever there is an imbalance between the two, it will result in a ventilation-perfusion mismatch.

  • Airway obstruction.

  • Depression of the respiratory center.

Anemic Hypoxia:

In this type of hypoxia, the lungs work fine, and there is an average partial pressure of oxygen in the arterial blood. Still, the amount of hemoglobin carrying oxygen is reduced due to anemia. The peripheral chemoreceptors are not stimulated as the dissolved oxygen in the blood plasma is sufficient enough to supply the chemoreceptors.

Causes of hypoxia include

  • Carbon monoxide poisoning.

  • Anemia of all types.

  • Excessive blood loss in the form of hemorrhage.

Stagnant Hypoxia:

In this type of hypoxia, there is reduced blood flow to the tissues. Although the partial pressure of oxygen in the arterial blood and oxygen content is expected, a sufficient amount of blood is not supplied to the tissues. It is also known as ischaemic or hypokinetic hypoxia.

Causes of hypoxia include

  • Sluggishness of blood flow.

  • Circulatory failure like congenital heart defects like the tetralogy of Fallot, ventricular septal defect, patent ductus arteriosus, and congestive heart failure in which the blood pumped by the heart is decreased, which leads to reduced blood flow to the tissues and thereby leading to stagnant hypoxia.

  • Localized stagnant hypoxia-like Raynaud's disease and Buerger's disease, where the blood supply to the extremities is reduced.

  • The shock is due to hypovolemia of blood in the body.

  • A stroke occurs due to a blood clot in the blood vessels, which blocks blood flow and oxygen supply to the brain.

Histotoxic Hypoxia:

In this type of hypoxia, although there is a normal partial pressure of oxygen dissolved in the arterial blood and the oxygen content is also standard, the capability of the tissues to utilize the oxygen is reduced. The peripheral chemoreceptors are stimulated.

The causes of hypoxia are

  • Cyanide poisoning.

  • Sulfide poisoning.

How Is Hypoxia Diagnosed?

Hypoxia can be diagnosed with the help of the following:

  • Arterial Blood Gas (ABG) Analysis: It includes the measurement of arterial oxygen, carbon dioxide, and pH. The calculation can be done with the help of the Henderson-Hasselbach equation, where pH is directly proportional to bicarbonate ions and indirectly proportional to carbon dioxide. The normal partial pressure of carbon dioxide is 35-45 mmHg; more than 45 mmHg is acidosis, whereas less than 35 mmHg is alkalosis. The normal partial pressure of bicarbonate ions ranges between 22-26 mmHg, where more than 26 is considered alkalosis and less than 22 is acidosis.

  • Pulse Oximetry: It is a probe that checks the oxygen saturation level of the blood.

  • Echocardiogram: An ultrasound helps diagnose the reason for hypoxia by checking the heart function.

  • Imaging: Chest X-ray or computed tomography (CT) scan can help diagnose infections or certain lung conditions.

How Is Hypoxia Treated?

Hypoxia is treated with oxygen administration.

  • Supplemental Oxygen Therapy: Oxygen is administered with the help of a cannula, facemask, or tracheostomy depending upon the medical condition and the patient's requirement.

  • Hyperbaric Oxygen Therapy (HBOT): Inhalation of 100 % oxygen at high barometric pressure. This allows the lung to take up three times more oxygen than breathing oxygen at standard pressure. It is indicated in cases of anemic hypoxia, carbon monoxide poisoning, decompression sickness, and air or gas embolism in scuba divers and mountain climbers.

  • Mechanical Ventilation: It is a machine that helps to breathe a critically ill patient who cannot breathe on their own. It is indicated in patients with severe acute hypoxia.

  • Treating the Underlying Cause: It may include the usage of bronchodilators, which may help in opening up the airways, a corticosteroid to subside the inflammation of the lung, or transfusing packed cells in an anemic patient.

What Are the Complications of Hypoxia?

Complications of hypoxia include

  • Brain damage and paralysis.

  • Cardiac arrest.

  • Gangrene.

How to Prevent Hypoxia?

Low oxygen levels in the blood do not have enough oxygen to supply the organs and tissues. This may lead to irreversible and permanent damage to the organs, including death, if it persists over time, specifically the heart and brain, requiring a constant supply of oxygen and nutrients. Acute cases of hypoxia can be fatal. Hypoxia can be prevented by taking certain precautions, such as management of underlying conditions that can lower oxygen levels and asking for any specific precautions if the patient has a compromised lung condition. Mountain climbers and scuba divers must carry oxygen cylinders.


Hypoxia is an emergency condition that requires immediate medical attention. Diagnosing early symptoms like confusion, increased heart rate, breathing, and bluish skin and mucous membrane discoloration requires immediate medical attention. Hypoxia should be treated right away to avoid irreversible organ damage. In some cases, it may require treating the underlying cause; in others, it may require supplemental oxygen therapy or hyperbaric oxygen therapy to resolve the condition.

Frequently Asked Questions


How Does Hypoxia Cause Fatigue?

Muscles need oxygen to function. Lack of oxygen (hypoxia) alters oxygen delivery to contracting skeletal muscle and affects muscle functioning. This increases the oxygen demand, but the muscles remain deprived of oxygen. As a result, it increases the rate of muscle fatigue.


How Does Hypoxia Lead to Fatty Change?

Hypoxia-inducible factors (HIF) regulate hepatic lipid metabolism. HIF-2 promotes lipid accumulation by preventing mitochondrial β-oxidation and promoting lipid droplet formation. In contrast, HIF-1 reduces lipid accumulation by inhibiting the formation of lipids.


How to Prevent Hypoxia?

The best way to reduce the risk of hypoxia is to manage any underlying conditions that can reduce oxygen levels. One must consult a doctor in case of any heart or lung conditions. One can also try yoga and breathing exercises that condition the lungs and improve breathing patterns. This helps to prevent hypoxia and breathing difficulties that might cause low oxygen levels.


What Are the Symptoms of Hypoxia?

Symptoms of hypoxia include restlessness, anxiety, confusion, rapid heart rate, bluish skin in severe cases of hypoxia, difficulty in breathing, fatigue, and weakness. One must watch out for these symptoms and consult a doctor for early diagnosis and treatments to avoid further complications. Severe cases of hypoxia may need immediate treatment to avoid permanent damage to vital organs like the brain and heart. 


Are Hypoxia and Hypoxemia the Same?

Hypoxia and hypoxemia aren't the same. Both these terms are related to low oxygen levels but in different parts of your body. Hypoxemia is low oxygen levels in your blood, and hypoxia is low oxygen levels in your tissues. Hypoxemia and hypoxia do not always coexist. Some people may develop hypoxemia without hypoxia if there is a compensatory rise in hemoglobin level and cardiac output. Similarly, some people may have hypoxia without hypoxemia.


What Level of Oxygen in the Body Is Considered as Hypoxia?

Hypoxia is when the oxygen levels in the body drop below the normal range, making the condition very fatal. Ideally, oxygen saturation levels should be between 92 and 98 percent for adults without an underlying respiratory condition. Oxygen levels lower than 92 percent in the body are considered hypoxic. 


How Does Hypoxia Stimulate Erythropoiesis?

Hypoxia causes the body's oxygen levels to drop, depriving the organs and tissues of oxygen. The body starts to initiate different responses to compensate for low oxygen levels (the body’s coping mechanism). The body tries to increase the number of red blood cells that carry oxygen efficiently into peripheral organs. 


Can Hypoxia Cause Death?

Brain cells are extremely sensitive to oxygen deprivation and can begin to die within five minutes after the oxygen supply has been cut off. If hypoxia persists for a longer duration, it can cause coma, seizures, and even brain death. 


How Does Hypoxia Affect the Heart?

Yes, hypoxia can affect the heart and cause various symptoms related to the heart. Hypoxia causes an imbalance between oxygen supply and oxygen demand. When the heart is deprived of oxygen for longer durations, the heart is challenged to produce a similar amount of ATP (energy) with limited oxygen for heart contractions and work to maintain normal heart function. It causes an increase in the heart rate. Severe cases may cause the heart to stop functioning.


How Does Hypoxia Affect the Kidneys?

Yes, hypoxia affects the kidneys. It causes a reduction in the glomerular filtration rate (filtration process of the kidneys). Initially, it increases the urine flow rate and causes a decrease in the percent sodium reabsorption due to hypoxic metabolic inhibition of solute reabsorption. This can impact the proper functioning of the kidneys and can also cause kidney damage.


Can Hypoxia Cause Brain Damage?

Neurons (brain cells) are extremely sensitive to low oxygen levels. Depending on the severity, brain cells die within the first five minutes due to a lack of oxygen. As a result, the brain stops functioning and can cause minor brain injuries or severe conditions like coma, stroke, seizures, or even death. Minor brain injuries are capable of recovery but are very rare. However, severe brain injuries are fatal.
Source Article IclonSourcesSource Article Arrow
Dr. Arpit Varshney
Dr. Arpit Varshney

General Medicine


Community Banner Mobile
By subscribing, I agree to iCliniq's Terms & Privacy Policy.

Source Article ArrowMost popular articles

Ask your health query to a doctor online

General Medicine

*guaranteed answer within 4 hours

Disclaimer: No content published on this website is intended to be a substitute for professional medical diagnosis, advice or treatment by a trained physician. Seek advice from your physician or other qualified healthcare providers with questions you may have regarding your symptoms and medical condition for a complete medical diagnosis. Do not delay or disregard seeking professional medical advice because of something you have read on this website. Read our Editorial Process to know how we create content for health articles and queries.

This website uses cookies to ensure you get the best experience on our website. iCliniq privacy policy