Hypopnea

Hypopnea (mostly spelled hypopnœa) is a medical term for a disorder involving episodes of overly shallow breathing or an abnormally low respiratory rate. Hypopnea is less severe than apnea, which refers to the complete cessation of breathing. Hypopnea may result in a decreased amount of air movement into the lungs and can cause oxygen levels in the blood to drop. It is more commonly due to partial obstruction of the upper airway.

Sleep-related Hypopnea

During sleep, hypopnea is classified as a sleep disorder. With moderate to severe hypopnea, sleep is disturbed, causing patients to experience a full night's sleep but still not feel rested because they did not get the right kind of sleep. The disruption in breathing causes a drop in blood oxygen level, which may disrupt the stages of sleep.

Daytime Hypopnea

Daytime hypopnea events are mostly limited to those with severely compromised respiratory muscles, as occurs in certain neuromuscular diseases. Daytime hypopnea can also cause a drop in blood oxygen level.

Etymology

Hypopnea comes from the Greek roots hypo- (meaning low, under, beneath, down, below normal) and pnoe (meaning breathing). Literally, it means underbreathing.

Diagnosis

In the context of diagnosis and treatment of sleep disorders, a hypopnea event is not considered clinically significant unless there is a 30% (or greater) reduction in flow lasting for 10 seconds or longer and an associated 4% (or greater) desaturation in the person's O2 levels, or if it results in arousal or fragmentation of sleep.

Causes

Among the causes of hypopnea are:

• Anatomical defects such as nasal septum deformation or congenital narrowness of nasal meatus and the gullet
• Acute tonsillitis and/or adenoiditis
• Obesity or being overweight
• Neuromuscular disease or any condition that entails weakened respiratory muscles
• Use of sedatives (sleeping pills, etc.)
• Alcohol abuse
• Smoking
• Aging
• Other factors, most of which are also typical causes of airway obstruction, snoring, and sleep apnea.

Symptoms

The most common hypopnea symptom is excessive sleepiness, which results from constant sleep interruption. People with hypopnea due to airflow obstruction often have loud, heavy snoring that is interrupted with choking sounds or loud snorts followed by periods of silence, because not enough air can flow into the lungs through the mouth and nose. The periods of silence can last 20 seconds or longer and can happen many times each hour, resulting in poor sleep and reduced levels of oxygen in the blood.

Other symptoms of hypopnea may include depression, forgetfulness, mood or behavior changes, trouble concentrating, loss of energy, nervousness, and morning headaches. Not all people with hypopnea experience all of these symptoms, and not everyone who has these symptoms has hypopnea.

Treatment

One treatment for hypopnea is continuous positive airway pressure (CPAP). CPAP is a treatment in which the patient wears a mask over the nose and/or mouth. An air blower forces air through the upper airway. The air pressure is adjusted so that it is just enough to maintain the oxygen saturation levels in the blood. For people with neuromuscular disorders, the most common treatment is the use of (BPAP or BIPAP) or other non-invasive ventilation.

Another treatment is a custom-fitted oral appliance. The American Academy of Sleep Medicine's protocol for obstructive sleep apnea (OSA) recommends oral appliances for those who prefer them to CPAP and have mild to moderate sleep apnea or those that do not respond to or cannot wear a CPAP. Severe cases of OSA may be treated with an oral appliance if the patient has had a trial run with a CPAP. Oral appliances should be custom-made by a dentist with training in dental sleep medicine.

Mild hypopnea can often be treated by losing weight or by avoiding sleeping on one's back. Quitting smoking, and avoiding alcohol, sedatives, and hypnotics (soporifics) before sleep can also be quite effective.

Surgery is generally a last resort in hypopnea treatment but is a site-specific option for the upper airway. Depending on the cause of obstruction, surgery may focus on the soft palate, the uvula, tonsils, adenoids, or the tongue. There are also more complex surgeries that are performed with the adjustment of other bone structures - the mouth, nose, and facial bones.

Consequences

Hypopnea is a disorder that may result in excessive daytime sleepiness and compromised quality of life, including traffic accidents, diminished productivity in the workplace, and emotional problems.

Cardiovascular consequences of hypopnea may include myocardial infarction, stroke, psychiatric problems, impotence, cognitive dysfunction, hypertension, coronary heart disease, and memory loss.

Prevention

To prevent or reduce the risk of developing hypopnea, individuals can adopt several lifestyle changes and healthy habits, such as:

• Maintaining a healthy body weight: Obesity is a significant risk factor for hypopnea, so losing weight through a balanced diet and regular exercise can help prevent or improve the condition.
• Practicing good sleep hygiene: Establishing a regular sleep schedule, creating a comfortable sleep environment, and avoiding stimulating activities before bedtime can promote better sleep and reduce the risk of sleep disorders.
• Avoiding alcohol and sedatives: These substances can relax the muscles of the upper airway, leading to an increased risk of hypopnea or worsening existing symptoms.
• Quitting smoking: Smoking can cause inflammation and irritation in the airway, increasing the likelihood of developing hypopnea.
• Sleeping on one's side: Lying on the back can cause the tongue and soft tissues to collapse to the back of the throat, partially obstructing the airway and leading to hypopnea. Sleeping on the side can help keep the airway open and reduce the risk of hypopnea.

See also

• Sleep apnea
• Obstructive sleep apnea
• Central sleep apnea
• Sleep disorders
• Continuous positive airway pressure (CPAP)

External links

• Hypopnea Info
• http://www2.merriam-webster.com/cgi-bin/mwmednlm?book=Medical&va=hypopnea
• http://www.emedicine.com/neuro/TOPIC419.HTM
• http://www.sleepdex.org/dyssomnias.htm
• http://www.sciencedaily.com/releases/2007/10/071015081737.htm
• http://www.aasmnet.org/Resources/PracticeParameters/PP_MedicalTherapyOSA.pdf

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