irregular numbers, new s9

[nativedancer]

recently, my dme exchanged a defective loaner for a brand new s9 vpap st. While using the loaner, my ahi had consistently been in the moderate 15-25 area. I have used the new machine for only 4 nights, but ahi's have not decreased to any great degree. Does a new machine take a while to adjust and begin giving accurate readings? Leaks have been close to 0, and my nights are generally undisturbed and restful, averaging 8hrs with only an occasional wake-up. Supplemental Oxy is 4.

I have noticed several replies to discouraged new members advising them to give therapy time to begin working. I wonder if we should perhaps give the machines a break as well.

I see the Dr soon and will bring the question up to him, but I would appreciate any input from board members.

[vsheline]

recently, my dme exchanged a defective loaner for a brand new s9 vpap st. While using the loaner, my ahi had consistently been in the moderate 15-25 area. I have used the new machine for only 4 nights, but ahi's have not decreased to any great degree. Does a new machine take a while to adjust and begin giving accurate readings?

Hi nativedancer,

If your therapy pressures change, yes, I think it may take a few days for things to settle. But if only the machine is changed and same settings are being used, maybe not?

Can you post some data from ResScan statistics or from SleepyHead?

Are you using the machine in ST mode?

What are your settings for backup respiration rate (10?), Trigger (Medium?), Cycle (Medium?), Ti Min (0.3 second?), Ti Max (2 second?), Rise Time (300 millisecond)?

The default value for Ti Min (0.3 second) is often too low, with 0.6 or higher often being better. If the Flow waveform ever shows the IPAP pressure is lasting much shorter than the time you are actually inhaling, I would suggest increasing Ti Min. Sometimes our inhalation may start haltedly or slowly and the machine may end IPAP prematurely, when our inhalation is just beginning.

Copied from setup manual (and edited):

ST (Spontaneous/Timed) mode
The VPAP augments any breath initiated by the patient, but will also supply additional breaths should the patient breath rate fall below the set “backup” breath rate.

Triggering and cycling
Under normal conditions, the VPAP triggers (initiates IPAP) and cycles (terminates IPAP and changes to EPAP) as it senses the change in patient flow. In addition, the VPAP has adjustable trigger/cycle sensitivity to optimize the sensing level according to patient conditions.

Adjustable trigger sensitivity
"Very High" means triggers into IPAP earliest, as soon as we begin to inhale.
"Very Low" means triggers into IPAP too late.

Adjustable cycle sensitivity
"Very High" means cycles back into EPAP too early, as soon as the inhalation Flow barely starts to decrease.
"Very Low" means cycles back into EPAP latest, after inhalation is fully complete.

Rise time adjustment (Default is 300ms)
Rise time sets the time taken for the VPAP to reach IPAP, in milliseconds. The greater the rise time value, the longer it takes for pressure to increase from EPAP to IPAP.

TiControl™ – Inspiratory time control
Unique to ResMed CPAP and bilevel devices, TiControl allows you to set minimum and maximum limits on the time the device spends in IPAP, in seconds. The minimum and maximum time limits are set at either side of the patient’s ideal spontaneous inspiratory time, providing a ’controlled period’ for the patient to spontaneously cycle to EPAP.
The minimum time limit is set via the Ti Min parameter (default is 0.3s) and the maximum time limit is set via the Ti Max parameter (default is 2.0s).

[nativedancer]

Thanks, vsheline. My sleepy is on vacation at the moment and I don't have all the info you wanted, but here are last night's numbers from the machine: 0 leaks, AI 25.5, AHI 26.7, MV 6.6, hrs 7.2. Dr has mode set on S rather than ST, but I don't know the difference between them. Ramp is off. Ti max 4, Ti min, .3, Rise time 300. trigger med, cycle med.
Pressure 20/12.

Dr's nurse called 6/18 to advise oximeter overnight test 2 wks ago had only 5 min usable data, but dme did not notify until asked on 6/18, sooo another roundedoo w/dme, requesting new oximeter test STAT, but naturally ups delivery has not happened as of 6/22, and next dr appt is 6/24. If oximeter does get here by 6/23, I will carry it w/me to dr on 6/24.

[nativedancer]

meant to add that pressure has not been changed on new machine.

[vsheline]

Dr has mode set on S rather than ST, but I don't know the difference between them.

In S therapy mode the machine synchronizes IPAP and EPAP to your natural or "Spontaneous" (meaning patient-initiated) breathing, rather than changing back and forth between IPAP and EPAP regardless of your natural breathing pattern like it does in T ("Timed") therapy mode.

If you stop breathing in S therapy mode the machine will do nothing except wait for you to start breathing again.

If you stop breathing in ST therapy mode the machine will step in and start cycling back and forth between IPAP and EPAP at a set backup respiration rate. If your apneas are central in nature then a high value for Pressure Support (such as 8 like PS is presently set to on your machine) may be high enough to do for you the work of breathing, keeping you ventilated so your blood O2 levels will remain adequate. When you start breathing again, it will synchronize itself to your natural respiration rate again.

I think your doctor should have your machine in ST therapy mode.

When you are able to post data (especially the Flow waveform and High Rate Pressure waveform) we may be able to tell from the Flow waveform whether the apneas look like they are central or obstructive.

Take care,
--- Vaughn

[nativedancer]

Thanks again, Vaughn. I see Dr tomorrow and will bring up the ST mode w/him. Your input always appreciated.

[nativedancer]

Vaughn, this may be premature, but two nights ago, I took your suggestion, and moved from S mode to ST. The numbers are the lowest I have ever experienced except during the brief foray I made to CPAP a while back: AI .9. AHI 3.5, and this despite a significant uptick in leaks, to 74. Last night the AHI climbed back up to 7, but was still far below the rather large moderate readings I've been having now for months, under various pressure changes. Sleepy continues to record the apneas as unclassified, but I don't really care what name they go by, so long as they remain "normal". I'll post again later when I have a firmer grasp on the situation.