Hypopnea
Hypopnea is a disorder characterized by shallow breathing and lower than normal rates of respiration. It differs from apnea in that the flow of air does not completely cease. Hypopnea is not that severe and is characterized by 26-69% of normal breathing and 4% or more reduction in oxygen levels in the bloodstream.
Sleep Apnea
Sleep apnea is a disorder which is characteristic of reduced breathing or a complete stoppage of breath. In sleep apnea, there is less than 25% of normal breathing or no breathing at all for 10 seconds or more and a 4% or more reduction in oxygen levels in the bloodstream.
Both the disorders cause a disturbance in sleep. Due to this, the individual may either completely wake up or move from deep sleep to a shallower stage of sleep.
The level of hypopnea or apnea can be found out through calculating indexes. These indexes indicate the extent of severity of the disorder so that timely intervention and treatment can be made available, where-ever necessary.
- AI – Apnea Index
- HI – Hypopnea Index
- AHI – Apnea-Hypopnea Index
- RDI – Respiratory Disturbance Index
RDI is the number of respiratory changes in an hour that may or may not be defined as apnea or hypopnea but that lead to sleep disturbances.
To be classified as a disorder needing treatment, the index must be at least 15 AHI/hour with no other related medical problems. Medical problems such as high blood pressure, daytime sleepiness, insomnia, congestive heart failure and mood disorders are worsened by apnea. If any of these medical problems are present in an individual, the index must be at least 5 AHI/hour or higher. Lower index levels are considered in such cases as treatment is necessary at a lower level to avoid aggravation of the above mentioned health problems.
Types of apnea
Apnea may be of different types depending on the causal factors.
- Central Sleep Apnea (CSA): The brain does not send messages to respiratory muscles to contract to breathe
- Obstructive Sleep Apnea (OSA): The brain sends a message to respiratory muscles to breathe but there is an inability to do so because of away blockage
- Combination of central sleep apnea and obstructive sleep apnea
Causes
- Anatomical defects like nasal septum deformation
- Obesity
- Neuro muscular diseases leading to weak respiratory muscles
- Intake of sedatives
- Smoking
- Alcohol intake
- Aging
Symptoms
- Excessive sleepiness
- Lethargy
- Fatigue
- Loud, heavy snoring
- Morning headaches
- Depression
- Trouble in concentration
It is, however, important to remember that these symptoms are not typical of apnea and may have other causes. Also, all apnea sufferers may not experience the said symptoms.
Consequences
Hypopnea and apnea are becoming common problems which may be a cause of worry. An increase in these disorders would mean an increase in the above mentioned medical conditions as well as greater incidences of cardiovascular disorders coupled with lower productivity and quality of life. It may also lead to greater number of road accidents, lower levels of productivity at work and emotional problems as well.
Treatment
The most common treatment is CPAP (Continuous Positive Airway Pressure). In this, the patient is given a mask to be worn over the nose and/or mouth that blows enough air into the upper air passage to keep it open and to maintain the oxygen levels in the bloodstream. BIPAP and other non-invasive methods are also frequently used. Surgery is suggested as a last resort and is usually very rare for these disorders.