Hypopnea-Clear Airway Questions

[Zippo]

I have my AHI usually between 2 and 3 with all events now being "hypopnea" or "clear airway". I've read the definitions of the terms but I guess I'm not sure I still understand what's going on. What is the difference - if any - between a "Hypopnea" and a "Clear Airway"? Is it possible to lower the incidence of each one and, if so, how?

Thanks!

[srlevine1]

I have my AHI usually between 2 and 3 with all events now being "hypopnea" or "clear airway". I've read the definitions of the terms but I guess I'm not sure I still understand what's going on. What is the difference - if any - between a "Hypopnea" and a "Clear Airway"? Is it possible to lower the incidence of each one and, if so, how?

Thanks!

The short version ...

Death is the total cessation of breathing forever.

Apneas are less severe than death and are the cessation of breathing for 10 seconds or more where the patient wakes up (arousal) to take a breath.

Hypopneas are generally less severe than apneas (unless they are present in great numbers) and represent shallow breathing or low respiratory rate (at least 30% decrease in airflow) for 10 seconds or more, leading to an arousal.

They are generated by:

Clear Airway (Central) apneas -- your airway is open but your brain forgot to tell you to breathe.

Obstructive -- your airway is partially or fully collapsed and you are still trying to breathe and you wake up to take a breath.

Complex -- a mixture of central and obstructive apneas.

Different machines and software may score the results differently.

To lower your AHI, one experiments with pressures and leak control. What works for some people may not work for others, so there is no formulaic answer. I suggest you continue reading posts in the forum to see what has worked for others and adopt those practices that work and ignore those that don't suit your needs. Some people may require different machines beyond a straight CPAP or APAP to deliver their therapy such as a bi-Pap or ASV machine.

Best of luck with your therapy.

[Sleeprider]

Good summary above from srlevine. With an AHI of 2-3 consisting of predominately CA and H events, you are well treated, and assuming you were using CPAP for obstructive sleep apnea, you have resolved that problem with the use of CPAP. CA and H events can be affected through settings on your machine, but it helps to see the relationship of those events with things like pressure, leaks, flow limitation, and periods of semi-sleep or waking. You have the software, and the links in my signature describe how to post it if you choose.

In a few people, the use of EPR may increase these types of events, so if you are using a EPR level of 3, it might be useful to see if using a lower setting might help. With OA events, more pressure is generally needed. With CA and H, sometimes less pressure variation or even lower pressure can be effective. As you can see, it amounts to a bit of trial and error, making changes one at a time, and using that change long enough to observe if the results represent a trend, rather than just an artifact.

[Zippo]

Thank you. I am using a Resmed S9 Auto. I'm sorry to be dense but if "Hypopnea" is an inclusive term for Clear Airway and Complex and Obstructive events (and I believe you when you say that it is) then why does my machine show Hypopneas and Clear Airways as if they were separate events?

[Sleeprider]

If you read the definitions of each of those terms, you will find they have different mechanisms and appearances when graphed on a respiratory flow chart. I'm not going to spoon feed this. Read the definitions http://www.apneaboard.com/wiki/index.php...efinitions

[chill]

Read carefully:

Hypopneas are less severe than apneas and represent shallow breathing or low respiratory rate (at least 30% decrease in airflow) for 10 seconds or more, leading to an arousal.

Clear Airway and Complex and Obstructive events (and death!) are a complete cessation of breathing. With a hypopnea, you are still getting some air, just not much. My sleep doctor called it Obstructive Apnea-lite.

[srlevine1]

Thank you. I am using a Resmed S9 Auto. I'm sorry to be dense but if "Hypopnea" is an inclusive term for Clear Airway and Complex and Obstructive events (and I believe you when you say that it is) then why does my machine show Hypopneas and Clear Airways as if they were separate events?

You appear to be confusing the definition and scoring of an event and the cause of the event.

Each manufacturer has their own scoring algorithm and if they can clearly distinguish between a central and obstructive event based upon the flow pattern, they will score them appropriately. These event markers and scoring are not always accurate. Hypopneas are of shorter duration and are harder to score -- so they often count as hypopneas without the machine attempting to determine the cause.

If you want to go deep in the weeds ...

Rules for Scoring Respiratory Events in Sleep: Update of the 2007 AASM Manual for the Scoring of Sleep and Associated Events

The New AASM Criteria for Scoring Hypopneas: Impact on the Apnea Hypopnea Index

[Zippo]

Read carefully:

Hypopneas are less severe than apneas and represent shallow breathing or low respiratory rate (at least 30% decrease in airflow) for 10 seconds or more, leading to an arousal.

Clear Airway and Complex and Obstructive events (and death!) are a complete cessation of breathing. With a hypopnea, you are still getting some air, just not much. My sleep doctor called it Obstructive Apnea-lite.

Ahhhh. Thank you! That makes a lot more sense to me now. I have few clear airway events now and many of my hypopneas occur during that sleep awake junk that someone else explained so well here or during large leak events so I think my actual numbers are lower than scored. Thanks again for the clear explanation.