After months of low AHIs, suddenly getting 8-12: why?

I've been investigating my reports of late (don't feel the least bit anxious about doing so ) and find something very interesting between the older Vpap Adapt and my new model machine. SleepyHead shows the following from last nights readings (01/20/14):
Mode: ASV
EPAP: 6.0 IPAP: 9.0 - 21.0 cmH2O
PS: 3.0 / 15.0

The following is taken from Dec 14, 2012 while I still had the older model:
Mode: ASV
EPAP: 6.0 IPAP: 11.0 - 19.0 cmH2O
PS: 5.0 / 13.0

I'm not sure if this is contributing at all to higher AHI readings.

It's entirely likely that the change in prescription is the reason for the increased AHI values. Was there any reason for the change our odds it sure to the DME setting up the new unit (incorrectly).

Personally, in your situation, I would change the current machine to the older settings, if it was working well.

Where I live we get no UVB from the Sun from about August to April. Vitamin D levels drop all that time.

Those who are working with the D3 hormone (A.K.A. Vitamin D3) (e.g. Dr. Stasha Gominak, Michael F. Holick, Ph.D., M.D., Vitamin D Council) seem to be finding that the very low side of the “normal” range of 30-100 ng/L produces a range of symptoms including OSA, pain, and infection. All believe that a level lower than 50 ng/mL is not good and Dr. Stasha Gominak recommends 60-80 ng/mL for good health.

It would probably be wise to check your vitamin D3 levels.

Sorry for the delaying in posting, and thanks again for all the suggestions everyone.

I agree that ASV masks may need to be changed more often because the pressure changes affect the mask over time, however I think the degree of stiffening (or softening) is mask-dependent. I use a F&P Simplus and have used Quattro and Liberty in the past. IMO The resmed masks do tend to stiffen over time, but my experience so far with the Simplus (5 months) is that it softens. I changed my seal at 3 months but on reflection I need not have bothered, and I plan to replace the current one with the old one and hope to get a total of 6 months out of each one. My therapist/tech said it should last 6-12 months, depending on how oily one's face is. My face became more oily when I started taking Omega 3 fish oil capsules.

My leak rate did go up (through the roof) along with the 9-12 AHIs, and it came down once I started getting 0.7-2.0 again. So I don't think it was the humidifier, but it was worth considering all the same. Good advice to replace tubing and headgear when needed. I will replace the tubing asap but not the headgear yet - only 5 months old and still functioning well. I tend to replace headgear once I can no longer tighten it enough.

My Vit D3 is in the normal range (the sun is brighter in Southern NZ than the US, and it's summer here). Good to think beyond sleep apnea - I have a number of medical issues and medications that make my case particularly complex, so at times it is hard work to unravel it all. But at the moment my sleep apnea is under control, so I am very happy about that.

I changed out my cushion on the Quattro Air less than a month in. My AHI came in at 0.9 last night. I think that there is some truth in the pressures from Vpap Adapt might be affecting the cushions and may need earlier replacement.

I used Resmed masks for the first 4 years of using ASV, and I had a terrible time with them. The F&P Simplus mask seems much better IMO. In another 6 months I'll be able to tell you how they do over time. So far so good.