Doctors Answers (6)
Overnight sleep studies can diagnose both obstructive sleep apnea and central sleep apnea, and are designed to distinguish between these disorders based on observed breathing patterns. Overnight sleep studies involve spending one night in the sleep laboratory during which sleep pattern, breathing pattern, oxygen level, heart rate and muscle activity are measured. Home sleep testing can also be used, which is typically limited to measuring breathing pattern, oxygen level and heart rate.
Central Sleep Apnea occurs when there is an obstruction in the upper airway similar to Obstructive Apnea but with a Central Apnea the brain does not send a signal to the rest of the body to awake and breathe. This can be diagnosed by being evaluated by a sleep specialist and having a Polysomnography (sleep study). During the sleep study your airflow (breathing pattern) will be monitored along with respiratory effort (your body's attempt to breath). If during the study your breathing stops and your body fails to respond to that lack of breath it is called Central Apnea.
Central apnea is diagnosed the same way as the obstructive sleep apnea, based on a sleep study done at a sleep lab. Home sleep tests are not good at picking central sleep apnea.
Obstructive Sleep Apnea occurs when the soft palate and tongue collapse and block the airway to the lungs. During this type of apnea the patient continues to try to breath and there will be movements of the chest and abdomen during these efforts. Central Sleep Apnea occurs when the respiratory center of the brain does not respond properly to the usual exchange of oxygen and carbon dioxide. Normally, while asleep we are dependent on our respiratory center in our brain stem to tell us when to inhale and exhale. When our respiratory center senses that there is enough oxygen we will exhale, then when the oxygen level drops we inhale. Actually, carbon dioxide plays a major role in this process but to simplify the explanation we often use the oxygen effect. Any condition that will adversely affect the respiratory center can result in Central Sleep Apnea. This could include a brain injury, a stroke, an infection of the brain, delayed circulation to the center such as with heart failure or anything that adversely affects our oxygen or carbon dioxide levels. This is much like a thermostat which is broken. You may set the temperature at 70 degrees but it may allow the temperature to go to 80 or 60 degrees. Interestingly, certain animals such as the whale have weak respiratory centers and are forced to sleep with only half their brain awake and half asleep. Otherwise, they would drown.
Central Apnea is occurs when the brain does not generate a signal to breathe. Obstructive Sleep Apnea occurs when the brain sends the signal for the body to breathe but something in the airway obstructs the flow of air. This can be diagnosed with a sleep study during which a variety of parameters are measured that can lead to the sleep physician to distinguish between the two. Obstructive Sleep Apnea is much more common.
Central sleep apnea (CSA) is defined as a cessation in airflow of 10 seconds or longer that is associated with aan absence of respiratory effort. Obstructive sleep apnea (OSA) is a cessation of flow with continued respiratory effort. Central apneas are seen commonly in patients with obstructive sleep apnea. CSA syndrome affects a heterogeneous mix of patients with central hypoventilation, neuromuscular diseas, idiopathic central sleep apnea and Cheyne-Stokes breathing associated with congestive heart failure.