Hypoxemia: Overview, Causes, Symptoms, Diagnosis And Treatment

what is hypoxemia?


Hypoxemia is the reduction in blood oxygen levels as compared to normal. If the blood oxygen levels are too low, the body may be unable to operate properly. It is a symptom of a respiratory or circulatory problem, and it may manifest itself in a variety of ways, including shortness of breath and fatigue.

The blood transports oxygen to all of the body’s cells, ensuring their health. Hypoxemia may cause mild symptoms like shortness of breath and headache, but it can also be deadly. It has the potential to damage heart and brain function in severe cases. Some other symptoms of hypoxemia include coughing, confusion, wheezing and discoloration of skin. If your blood is depleted of oxygen, it will be unable to provide adequate oxygen to the organs and tissues that need it to operate correctly. If the disease is severe, it may be fatal, and if it lasts for a long period of time, it can cause significant heart and brain damage.

Hypoxemia may be triggered by a number of different diseases, including pneumonia, asthma, and COPD. It is a medical emergency that requires immediate medical care.

Hypoxemia is detected by measuring the oxygen saturation of blood obtained from an artery. Another approach is to monitor the blood oxygen saturation using a pulse oximeter. A pulse oximeter is a little gadget that attaches to the finger and measures the blood’s oxygen saturation.

A pulse oximeter typically measures normal oxygen saturation levels between 95 and 100%. As per the oxygen level chart, low blood oxygen levels refer to blood oxygen levels that are less than 90%.

If the oxygen needs continue to rise while the oxygen saturation levels remain low then this condition is referred to as refractory hypoxemia.

Physical exams, oxygen monitors or pulse oximeters, the measurement of oxygen levels in blood gas samples, and the execution of pulmonary function tests are used to diagnose hypoxemia.

The aim of treating hypoxemia is to give as much additional oxygen as possible to the patient. While the methods employed vary greatly depending on the patient’s condition, they may include oxygen given through a nasal cannula or face mask and intubation or mechanical ventilation. Medicines that expand the airways are also given.


The variables that cause tissue hypoxia frequently cause the intermediate condition of hypoxemia; therefore, the factors that cause any kind of hypoxia may also cause hypoxemia. Hypoxemia may be triggered by a number of different causes, including the following:

Carbon Monoxide Poisoning

Inhaling carbon monoxide from sources like faulty heaters or car exhaust can displace oxygen in the blood, causing hypoxemia.


It is characterized by lung blockage in which air cannot enter the lungs. COPD is characterized by the deterioration of the alveolar walls and surrounding capillaries, which results in decreased oxygen exchange and hypoxemia.


It occurs if the body cannot generate enough RBCs to carry adequate oxygen throughout the body. As a consequence, anemia patients may have low levels of oxygen in their blood.

High Altitudes

Exposure to high altitudes where the air pressure is lower can reduce the oxygen available for inhalation, leading to altitude-induced hypoxemia.

Heart Problems

Certain heart conditions, like congestive heart failure or congenital heart defects, can impair the heart’s ability to pump oxygen-rich blood effectively.

Lung failure

As a warning indicator, hypoxemia may sometimes indicate the presence of an underlying disease like respiratory failure. Lung failure happens when the lungs are unable to deliver enough oxygen into the bloodstream to keep the person alive. A low blood oxygen level may be a symptom of respiratory failure in certain individuals.

The other conditions that also cause hypoxemia are listed below:

  • Asthma
  • Pulmonary embolism i.e. blood clot in the lungs
  • Heart defects or diseases
  • Pneumonia
  • Pulmonary fibrosis i.e. lung scarring
  • High altitudes
  • Lung disease
  • Pulmonary edema i.e. fluid retention in the lungs

Some medications also have the potential to lower the oxygen levels in the blood. Medicines that lower the breathing rate like anesthetics and narcotics also result in hypoxemia.

Acute hypoxemia may occur in infants with heart abnormalities or other illnesses. In infants born, the oxygen saturation level in the blood is tested to rule out congenital cardiac problems. Preterm infants, particularly those on mechanical breathing, are susceptible to hypoxemia.

Symptoms of Hypoxemia

The signs of hypoxemia may differ based on how severe it is and what’s causing it. These typical symptoms encompass:

  • Shortness of Breath: Difficulty breathing, particularly during physical activity or at rest.
  • Rapid Breathing: An increased respiratory rate as the body attempts to compensate for reduced oxygen levels.
  • Cyanosis: Bluish discoloration of the skin, lips, or nail beds due to inadequate oxygen supply.
  • Confusion or Cognitive Changes: Impaired mental clarity, confusion, difficulty concentrating, or changes in alertness.
  • Fatigue: Unusual tiredness or weakness that may affect daily activities.
  • Chest Pain: Discomfort or pain in the chest, especially in cases associated with heart-related hypoxemia.
  • Dizziness or Lightheadedness: Feeling unsteady or faint due to oxygen deprivation.
  • Headache: Often described as a throbbing or pounding sensation.


Hypoxemia, a condition marked by reduced oxygen levels in the blood, can be identified through a combination of clinical evaluation and medical examinations. The following steps are involved in diagnosing hypoxemia:

Clinical Assessment

Healthcare professionals begin by conducting a comprehensive clinical evaluation. They inquire about your medical history, including any pre-existing respiratory or cardiac conditions, and inquire about symptoms such as breathlessness, rapid breathing, or bluish skin or lips (cyanosis).

Physical Examination

A physical examination is carried out to assess vital signs, including heart rate, respiratory rate, and blood pressure. Healthcare providers may also use a stethoscope to listen for abnormal lung sounds or heart murmurs.

Pulse Oximetry

Pulse oximetry is one of the initial tests. It involves attaching a small device, known as a pulse oximeter, to your finger, earlobe, or toe. This device measures the oxygen saturation level (SaO2) in your blood. A SaO2 reading below 95% indicates hypoxemia.

Arterial Blood Gas (ABG) Analysis

For a more precise evaluation of blood oxygen levels, an arterial blood gas analysis may be performed. This entails taking a small blood sample from an artery, typically from the wrist. The blood sample is then analyzed to measure oxygen (PaO2) and carbon dioxide (PaCO2) levels in the arterial blood. A PaO2 value below the normal range (usually less than 80 mm Hg) confirms the presence of hypoxemia.

Chest X-rays and Imaging

In cases where the underlying cause of hypoxemia is suspected to be linked to lung or heart issues, healthcare providers may order a chest X-ray or other imaging studies like a CT scan. These tests help identify structural abnormalities, infections, or fluid accumulation in the lungs or heart.

Pulmonary Function Tests

When a respiratory condition is suspected, pulmonary function tests such as spirometry or lung function testing may be conducted to assess lung function and capacity.

Cardiac Evaluation

If there is suspicion of a heart-related issue, electrocardiography (ECG or EKG) and echocardiography (ultrasound of the heart) may be employed to assess heart function and identify potential cardiac causes of hypoxemia.

Laboratory Tests

Blood tests may be carried out to check for underlying conditions such as anemia or infections that could contribute to low oxygen levels.


The treatment of hypoxemia aims to target the root cause and enhance oxygen levels within the bloodstream. Various treatment options are available, including:

  1. Supplemental Oxygen: Oxygen therapy involves delivering extra oxygen to boost the oxygen saturation in the blood.
  2. Medications: Treatment may involve using specific medications to address the underlying conditions, such as bronchodilators for managing asthma or antibiotics to combat pneumonia.
  3. Implementing Lifestyle Adjustments: Making lifestyle changes like quitting smoking, maintaining a healthy weight, and effectively managing chronic ailments like COPD or heart disease can contribute to the enhancement of oxygen levels.
  4. Mechanical Ventilation: In severe instances, the use of a ventilator may become necessary to provide vital breathing support.
  5. Engaging in Pulmonary Rehabilitation: Participating in a structured program that encompasses exercise, education, and support can aid in improving lung function and overall health.

When to see a doctor

If you notice any of the symptoms and signs of hypoxemia, you should contact your doctor immediately. If you get an early diagnosis and treatment, you may be able to prevent the disease from deteriorating and perhaps killing you. Consult your primary care physician right away if you have any of the following symptoms:

  • shortness of breath
  • Rapid heartbeat
  • Fluid retention
  • Breathlessness that intensifies with exercise or other physically demanding tasks
  • Sleep apnea, a respiratory condition that disrupts the sleep cycle, is characterized by difficulty breathing or a suffocating feeling
  • Feeling disoriented 

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