Hypoxemia (low blood oxygen)

DEFINITION

Hypoxemia, or low blood oxygen, describes a lower than normal level of oxygen in your blood. In order to function properly, your body needs a certain level of oxygen circulating in the blood to cells and tissues. When this level of oxygen falls below a certain amount, hypoxemia occurs and you may experience shortness of breath.

Your doctor determines whether you have hypoxemia by measuring your blood oxygen level — the amount of oxygen traveling in your arteries. Your blood oxygen can be measured by testing a sample of blood from an artery.

An approximate blood oxygen level can also be estimated using a pulse oximeter — a small device that clips on your finger. Though the pulse oximeter actually measures the saturation of oxygen in your blood, the results are often used as an estimate of blood oxygen levels. Normal pulse oximeter readings range from 95 to 100 percent, under most circumstances. Values under 90 percent are considered low.

CAUSES

Common causes of hypoxemia include:

1. A blocked airway
2. Anemia
3. ARDS (acute respiratory distress syndrome)
4. Certain medications, such as narcotics and anesthetics, which depress breathing
5. Congenital heart disease — heart defects that are present at birth
6. COPD (chronic obstructive pulmonary disease)
7. Emphysema
8. High altitudes
9. Interstitial lung disease
10. Pneumonia
11. Pneumothorax
12. Pulmonary edema
13. Pulmonary embolism
14. Pulmonary fibrosis
15. Sleep apnea

WHEN TO SEE A DOCTOR

Call 911 or get emergency medical help if you have:

• Severe shortness of breath that comes on suddenly and affects your ability to function
• Severe shortness of breath with headache, insomnia, fluid retention and cough at high elevations (above 8,000 feet, or about 2,400 meters) — these are signs and symptoms of high-altitude pulmonary edema, which can be fatal without appropriate care

See your doctor as soon as possible if you have:

• Shortness of breath after slight exertion or when you’re at rest
• Shortness of breath that gets worse when you exercise or are physically active
• Abrupt awakenings with shortness of breath or a feeling that you’re choking — these may be symptoms of sleep apnea

Self-care

To cope with chronic shortness of breath try to:

• Stop smoking. If you’ve been diagnosed with COPD or other lung disease, the single most important thing you can do is to quit smoking.
• Avoid passive smoke. Avoid places where others smoke. Secondhand smoke can cause further lung damage.
• Get regular exercise. It may seem difficult to exercise when you have trouble breathing, but regular exercise can improve your overall strength and endurance.