What's a "clear airway" and why does it show up ?

DeeCPAP wrote:I've never seen 'clear airway' show up in SleepyHead, but suddenly, I'm finding quite a few.

Can anyone explain?

Thanks

Wulfman... wrote:

DeeCPAP wrote:I've never seen 'clear airway' show up in SleepyHead, but suddenly, I'm finding quite a few.

Can anyone explain?

Thanks

Please feel free to search the archives of the forum:

viewtopic/t158231/search.php?keywords=% ... +airway%22


Den

.

palerider wrote:"clear airway" is a term made up by respironics... the rest of the respiratory industry uses the term "central".

JDS74 wrote:Sometimes just as the transition between being awake and being asleep occurs, you get one of these. They can also show up when the pressure is high (for you). Noticing one just as you are going to sleep is an indication of the first cause and is nothing to worry about (neither is the second for that matter but reducing the max pressure might be required to control them.)

Jas_williams wrote:I would not be concerned with the CA’s at the moment kind of look like you holding four breath whils rolling over (the one in the middle of the night) I would be more concerned with the amount of leaks going on that needs resolving as it will be reducing the effectiveness of your therapy

What is Clear Airway Apnea?

An apnea is detected when there is an 80% reduction in airflow from a baseline for at least 10 seconds if there is no airflow detected for 10 seconds. During the apnea, one or more pressure test pulses are delivered by the device. The device evaluates the response of the patient to the test pulse(s) and assesses whether the apnea has occurred while the patient has a clear airway or an obstructed airway. The airway is determined to be clear if the pressure test pulse generates a significant amount of flow; otherwise the airway is determined to be obstructed. When the airway is clear then a Clear Airway Apnea event is recorded.

-- https://www.mysleepmapper.com/Help/Faq

Clinicians also need to be aware that a device-detected apnea identified by the device as having a clear airway is not always a central apnea and a device-detected apnea identified by the device as having an obstructed airway is not necessarily an obstructive apnea. . . . Airway status determined by the PAP device does not distinguish obstructive from central apneas scored by PSG. For example, an obstructed airway was detected in about a third of device-detected apneas that were scored as central apneas on PSG. Although it is not possible to use PSG signals to determine if the pharyngeal airway is clear or obstructed during a central apnea, it is well known that the airway may be closed during this event. Badr et al. used a transnasal fiberoptic scope to view the pharyngeal airway in subjects with sleep apnea during nonrapid eye movement sleep and observed pharyngeal airway collapse during central apneas that were either spontaneous or induced by mechanical hypocapnic hyperventilation. The device uses its airway status determination to decide whether to change pressure delivery. Determination of an obstructed airway, even if it might be a central apnea, warrants an increase in pressure by the device in order to open the airway and allow resumption of airflow. The device classified 13% of the obstructive apneas on PSG as having a clear airway. This may be explained by the different criteria used by the PAP device and manually scored PSG to identify an apnea. The device defines an apnea as at least an 80% reduction from baseline in pneumotach airflow, whereas 2007 AASM criteria for an apnea on PSG require at least a 90% reduction in airflow on oronasal thermistor. However, it can be hypothesized that the pharyngeal airway during an obstructive apnea may open during active expiratory efforts and collapse again on inspiration. Under this circumstance, it is possible that a pressure pulse that occurred during expiration may have resulted in airflow. The device also detected an obstructed airway in about 44.1% of manually scored hypopneas. It is possible that when the narrowed pharyngeal airway has a very high airway resistance, the relatively small pressure pulse generated by the PAP device results in very blunted airflow; a response that the device would identify as an obstructed airway. PAP downloads report the same variables obtained on PSG, including AHI, AI, HI, and RERAI. However, the methods used in PAP devices and PSG to generate these measures differs markedly. Respiratory events detected by the PAP devices are based solely on measurement of airflow. In contrast, multiple signals are used to score respiratory events on PSG, including airflow, arterial oxygen saturation, chest wall movement, and, depending on the scoring criteria, electroencephalographic (EEG)/electromyographic (EMG) arousals. -- https://academic.oup.com/sleep/article- ... .4.597.pdf