hypopnea

[jerry1967]

Can someone tell me why when hypopnea register on my machine it doesn't raise my air pressure?

I have a ResMed Airsense 10 AutoSet pressure is set at 12.6-18 with pressure relief at 1.

My numbers are high I need an ASV but don't want to have another test.

My AHI is around 15-22 divided among Centrals and hypopneas

[Gideon]

Please show some detailed charts where this is demonstrated.

[Stom]

Can someone tell me why when hypopnea register on my machine it doesn't raise my air pressure?

I have a ResMed Airsense 10 AutoSet pressure is set at 12.6-18 with pressure relief at 1.

My numbers are high I need an ASV but don't want to have another test.

My AHI is around 15-22 divided among Centrals and hypopneas

Does the A10 even respond to hypopneas, per se? Hypopneas are flow restrictions, so I'm wondering if the A10 responds to them based on the flow limitations? Neither ResMed nor this paper on CPAP algorithms use the word "hypopnea" when talking about the A10s response, but I can't tell if they mean to include apneas and hypopneas toghether under "apnea" or if they are being precise and mean apnea only.

ResMed clinical guide for the A10:

Obstructive apnea

An obstructive apnea is when the upper airway becomes severely limited or completely obstructed. AutoSet generally prevents obstructive apneas from occurring by responding to flow limitation and snoring. If an obstructive apnea occurs, the device will respond by increasing pressure.

From Treatment of sleep-disordered breathing with positive airway pressure devices: technology update, Karin Gardner Johnson, Douglas Clark Johnson, 2015:

OA/hypopnea response
Increases pressure based on current pressure every 10 s of apnea: increment max 3 when pressure is 4. Increment drops linearly down to 0.5 when pressure is 20. S8: no increase above 10...

Flow limitation response
S9: uses 3 breath average FL index. Increment typically around 0.6/breath for severely flow limited breaths. Lower increment if lower FL index, high leak or as pressure increases further above 15; S10: increment max 0.6/breath otherwise same as S9.

[Sleeprider]

Jerry, in your case the hypopnea are probably central and the machine does not respond to central events. The Resmed machine will respond strongly to flow limitation, which has a characteristic flat or downward slope to the inspiration peak. Since your flow rate is dropping with the hypopnea, but not showing flow limitation, it does not increase pressure. If the hypopnea was due to flow limitation, the algorithm does pick that out and properly raises pressure.

You clearly need the ASV. Have you looked at Supplier #2 for their lightly used and new ASV machines? Very good prices. I understand your reluctance to have another sleep test, but your AHI is very high and your auto CPAP cannot resolve this problem.

[Stom]

Ah, sleeprider's post highlights an error I made in mine. Hypopneas are reduced inspiration, but not necessarily a "restriction".