Alveolar hypoventilation syndrome

Alveolar Hypoventilation Syndrome

Description, Causes and Risk Factors:

Abbreviation: AHS.

Other Names:

    Primary alveolar hypoventilation.

  • Nonapnic alveolar hypoventilation.

  • Idiopathic central alveolar hypoventilation.

  • Central alveolar hypoventilation.

This malady happens when oxygen levels are low while breathing at night. It is a rare condition, and sometimes happens during daytime as well. Because of lowered breathing volume, less air moves into and out of the lungs. This disturbs sleep causing excessive daytime sleepiness or insomnia. Lowered oxygen levels can also lead to high blood pressure and sometime even heart failure. The cause of Alveolar Hypoventilation Syndrome is unknown. Some patients have a specific genetic defect. The disease mainly affects men 20 to 50 years old, although it may also occur in young boys.

The main feature of this condition is reduced breathing volume. This means that there is less air coming into and going from your lungs. This problem often disturbs your sleep. It can cause insomnia or excessive daytime sleepiness. It can also cause you to have a headache when you wake up in the morning.

Risk Factors:

It is more common in men. People using certain medications have higher incidence, as these medicines make the breathing pattern shallow. Some examples:


  • Painkillers.

  • Anti-anxiety medications.

  • Sleeping pills.


Symptoms of Alveolar Hypoventilation Syndrome include:


  • Lethargy.

  • Morning headaches.

  • Bluish coloration of the skin caused by lack of oxygen.

  • Daytime drowsiness.

  • Swelling of the ankles.

  • Waking up from sleep unrested.

  • Waking up many times at night

Complications: Chronic hypoventilation may be associated with congestive heart failure, cor pulmonale and angina.


The differential diagnosis includes upper airway resistance syndrome, central sleep apnea syndrome, central alveolar hypoventilation syndrome and primary snoring.

The doctor will want to know about your entire medical history. You should also describe any sleep related problems that you have. Report if you have shortness of breath at night or during the day. Tell your doctor if you have swelling in your feet, legs or arms. Your doctor will also want to know if you ever notice that your fingers, toes or lips turn a bluish color.

Alveolar hypoventilation syndrome

Evaluation of a patient with hypoventilation requires a combination of clinical history, physical examination, pulmonary function testing, and chest radiography to help determine the cause. Specialized testing such as measurement of respiratory muscle strength and assessment of ventilatory control may also be needed. Genetic testing may help make the diagnosis of some disorders such as the central congenital hypoventilation syndrome. In some patients the first laboratory clue that chronic hypoventilation is present is to note an unexplained elevation in the serum CO2 (HCO3) on routine electrolyte testing. Nocturnal oximetry and polysomnography are usually required to determine if obstructive or central sleep apnea is present in addition to nocturnal hypoventilation. In addition, the severity of daytime hypoventilation or pulmonary function impairment often does not accurately predict the severity of nocturnal changes in arterial oxygen saturation and the degree of nocturnal hypoventilation. End-tidal PCO2 and transcutaneous PCO2 are sometimes utilized to directly estimate the degree of nocturnal hypoventilation during sleep studies. They have limitations but may be especially useful to detect trends in the PCO2 during the night.

Tests that may be done include:

    Blood gases.

  • Chest x-ray.

  • Hematocrit and hemoglobin blood tests.

  • Overnight oxygen level measurements (oximetry).

  • Lung function tests.

  • Sleep study (polysomnography).


The first step is to determine if another medical problem is the cause of this sleep related breathing disorder. First, the doctor will determine if any other sleep disorder is the cause of your shallow breathing to target the underlying issue. While your doctor evaluates your condition, he or she may place you on oxygen at night. This will help improve your oxygen levels. To use the oxygen, you normally wear a small plastic tube in your nose. This is called a cannula. Often you only need to use this at night when you sleep. Sometimes a small BPAP machine is used instead of or in addition to oxygen. BPAP stands for bi-level positive airway pressure.

The physician may put you on oxygen to improve its levels. You would need to wear a plastic tube called cannula in your nose. This may be required only at night. In addition, you may be asked to use a BiPAP machine. This give pressurized air to the lungs and improves the exchange of carbon dioxide and oxygen.

Disclaimer: The following tests, drugs and medications, surgical procedures are in some way related to, or used in the treatment. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.

DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.


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