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Hypoventilation/Hypoxemia Due to Lower Airways Obstruction

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What is it?

This disorder is caused by a reduction or narrowing of the size of your airway. It can also be caused by resistance to proper airflow. This causes the lungs to function poorly. They are unable to exchange oxygen and carbon dioxide properly.

People with a lower airway obstruction are more likely to have hypoventilation that occurs at night. As the airway obstruction gets worse, the degree of hypoventilation is likely to worsen as well.

Low oxygen levels during sleep can cause headaches, heart problems and poor daytime functioning. It can also disturb the quality of your sleep. Sleep related problems can include the following:

  • Difficulties getting to sleep
  • Difficulties staying asleep
  • Reduced stages of deep sleep
  • An increased number of awakenings during the night

Other names for this disorder include the following:

  • Low nocturnal oxygen saturation
  • Nocturnal hypoxemia
  • Nocturnal oxygen desaturation
  • Secondary alveolar hypoventilation
  • Sleep related hypoxemia
  • Sleep related oxygen desaturation

Who gets it?

People with a medical problem that causes a lower airways obstruction or restriction are at higher risk for hypoventilation. These problems include:

  • Chronic bronchitis
  • Emphysema
  • Alpha-1 antitrypsin deficiency
  • Bronchiectasis
  • Cystic fibrosis

Cigarette smoking is the single greatest risk factor for developing a disorder that restricts the lower airways.

It can also occur in people who have sleep apnea.

Other factors that can contribute to this problem include the following:

  • Chemical exposures
  • Environmental factors
  • Pollutants

How do I know if I have it?

  1. Do you have a disease that produces lower airways obstruction or restriction?

  2. Has an overnight sleep study or arterial blood testing during sleep shown oxygen levels less than 90% for more than 5 minutes? Or has it shown 30% or more of sleep time with oxygen levels less than 90%? Or has blood testing demonstrated elevated levels of carbon dioxide?

  3. Is your medical problem thought to be the primary cause of hypoventilation?

  4. Are there no other disorders present that can explain the breathing problem?

If your answer to these questions is “yes,” then you might have sleep related hypoventilation/hypoxemia due to lower airways obstruction.

Do I need to see a sleep specialist?

You should strongly consider seeing a sleep specialist if you have an obstructive lung disease. This puts you at higher risk of having nocturnal hypoventilation.

What will the doctor need to know?

Your doctor will want to know about your entire medical history. This includes any breathing problems you may have. Details about your typical sleep patterns and any sleep struggles are important. This is true even if your problems only seem to occur during the day.

Will I need to take any tests?

You may need to take an arterial blood gas test to find out how much carbon dioxide is in your blood. Elevated carbon dioxide levels during sleep are a sign of this disorder.

Your doctor may also determine that you have it if you regularly have low levels of oxygen, and you don’t have sleep apnea.

How is it treated?

It is important to begin by treating the cause of the airway obstruction. This will improve both daytime and nighttime breathing patterns.

If sleep apnea is also present, then CPAP or BPAP therapy may be used. This requires that you wear a small mask over your nose at night. It provides a steady stream of air to help you breathe deeply. This gives you a more efficient exchange of oxygen and carbon dioxide.

Sometimes oxygen is provided to help with this condition. It may be supplied with or without a CPAP or BPAP device. This will help maintain the level of oxygen in your blood. But there is the chance that it will make your carbon dioxide levels worse. A doctor must monitor your treatment closely.

By Donald R. Townsend, PhD
Updated April 25, 2006

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