Blood oxygen saturation

Blood Oxygen Saturation

Blood oxygen saturation, often referred to as oxygen saturation or SpO2, is a measure of the amount of oxygen-carrying hemoglobin in the blood relative to the amount of hemoglobin not carrying oxygen. It is a critical parameter in assessing a patient's respiratory function and overall health.

Physiology

Oxygen is transported in the blood primarily bound to hemoglobin, a protein in red blood cells. Each hemoglobin molecule can bind up to four oxygen molecules. The percentage of hemoglobin molecules carrying oxygen is referred to as the oxygen saturation level. Normal oxygen saturation levels typically range from 95% to 100% in healthy individuals.

The process of oxygen binding to hemoglobin is influenced by several factors, including the partial pressure of oxygen (PaO2), carbon dioxide levels, pH, and temperature. The relationship between PaO2 and SpO2 is described by the oxygen-hemoglobin dissociation curve.

Measurement

Oxygen saturation is commonly measured using a device called a pulse oximeter. This non-invasive device uses light absorption through a pulsating capillary bed, usually at the fingertip or earlobe, to estimate the percentage of oxygenated hemoglobin.

In clinical settings, arterial blood gas (ABG) analysis can provide a more precise measurement of blood oxygen levels, including PaO2 and SaO2 (arterial oxygen saturation).

Clinical Significance

Monitoring blood oxygen saturation is crucial in various medical conditions, including:

• Chronic obstructive pulmonary disease (COPD)
• Asthma
• Pneumonia
• Congestive heart failure
• Sleep apnea

Low oxygen saturation, known as hypoxemia, can lead to symptoms such as shortness of breath, confusion, and cyanosis. Severe hypoxemia can be life-threatening and requires immediate medical intervention.

Factors Affecting Oxygen Saturation

Several factors can affect oxygen saturation readings, including:

• Altitude: Higher altitudes have lower oxygen levels, which can reduce SpO2.
• Carbon monoxide poisoning: Carbon monoxide binds to hemoglobin more effectively than oxygen, reducing oxygen saturation.
• Anemia: Low hemoglobin levels can affect the overall oxygen-carrying capacity of the blood.

Also see

• Hemoglobin
• Respiratory system
• Arterial blood gas
• Pulse oximetry
• Hypoxemia

Resources

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Source: Data courtesy of the U.S. National Library of Medicine. Since the data might have changed, please query MeSH on Blood oxygen saturation for any updates.

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