My first night on ASV

James,

Re the headache, this may be due to CO2 retention. I am finding as I get to know my Bipap AutoSV more, that I can get great data but still begin to hit periods of drowsiness and can predictably bump up the risetime (from 3 to 2) to clear these.

Interestingly, the Vpap AdaptSV which has few adjustments seems to automatically drive the respiration at a rate that prevents CO2 retention but at the same time creates the feeling of not sleeping deeply.

For myself I feel I am fine tuning the pressures & the risetime to
1) minimize ai & hi events (epap & ipap) &
2) minimize CO2 retention (risetime too slow)

The above juggling act for me seems to be a balance of ...
- Mask type & venting
- my state of health (fitness & exercise)
- medication (gerd)
- alcohol consumption
- pressure & risetime settings

Looking at your data & listening to your comments, you are still fine tuning the pressure settings and are probably ready to
look into possible co2 retention issues (risetime settings).

If I were to suggest a change it would be to increase risetime by 1 & see how that impacts.

Good luck

Doug

and increase IPAP Min=14.

James

This brief doc may help explain where I am coming from. It follows on Bev's comments re her headaches when using PS and Bilevel on her Bipap AutoSV but not having headaches when she turned off the bilevlel aspect of her machine & ran it as CPAP with PS.

At the time I hadn't joined the dots enough to suggest to her to adjust risetime up if she activates bilevel as well as PS. I am now thinking that any of us on a Bipap AutoSV needs to get the CO2 retention sorted out as while the Bipap AutoSV is a very adjustable machine few people have had enough understanding (including me) to recognise when CO2 retention is becoming a problem.

The part that caught my eye in the below was the issue of CO2 retention being associated with cluster headaches in people with SDB.

DSM

http://cat.inist.fr/?aModele=afficheN&cpsidt=1422808
"Article abstract-Objective: To study subjects with active or inactive cluster headache (CH) for occult sleep disordered breathing (SDB). Background: CH frequently occurs during sleep. The authors previously found that symptoms of SDB predicted reported occurrence of CH in the first half of the night, which suggested that CH could be triggered in some cases by unrecognized SDB. Methods: The authors performed polysomnography in 25 adults (22 men) with CH. Subjects were not selected for any sleep-related complaint. In addition to standard measures, studies included monitoring of end-tidal carbon dioxide (n = 22), and esophageal pressure (n = 20). Results: The rate of apneas and hypopneas per hour of sleep was >5 in 20 subjects (80%; 95% CI, 64% to 96%), minimum oxygen saturation was <90% in 10 subjects, maximum negative esophageal pressure ranged from -13 to -65 cm H2O and maximum end-tidal carbon dioxide was ≥50 mm Hg in eight subjects. The eight subjects with active (versus inactive) CH at the time of study had higher maximum end-tidal carbon dioxide levels (50 ± 3 versus 44 ± 5 mm Hg; p = 0.0007). More severe oxygen desaturation was associated with reports that CH typically occurred in the first half of the nocturnal sleep period (p = 0.008). Conclusions: SDB occurred in the majority of patients with CH. Evaluation of a patient with CH should include consideration that SDB may be present."

"Article abstract-Objective: To study subjects with active or inactive cluster headache (CH) for occult sleep disordered breathing (SDB).

I had no clue members of the occult were also practicing sleep apnea. I'll have to be more careful when I sleep...

This disorder is more dangerous than I ever would have thought.

-SWS wrote:

"Article abstract-Objective: To study subjects with active or inactive cluster headache (CH) for occult sleep disordered breathing (SDB).

I had no clue members of the occult were also practicing sleep apnea. I'll have to be more careful when I sleep...

This disorder is more dangerous than I ever would have thought.

Mais mon bon monsieur, cet article a été traduit de l'anglais.

Je vais parler à l'éditeur d'en obtenir la rectification.

DSM

Excellent point about the French-to-English translator probably having mistranslated. Here's my best guess about that meaning or translation:

occult SDB = obscured SDB = undiagnosed SDB

But even members of the occult surely must get SDB... Very seriously, thanks for the article, Doug!

on edit: I think occult is a genuine medical term in English.

# Hidden from view; concealed.
#

1. Medicine. Detectable only by microscopic examination or chemical analysis, as a minute blood sample.
2. Not accompanied by readily detectable signs or symptoms: occult carcinoma.

http://www.answers.com/occult

Just to add a good comparison chart. The attached link shows 2 nights - settings are unchanged night to night EXCEPT risetime was speeded up from 3 (300 milisecs ) to 2 (200 milisecs). (Last night & the night before).

The difference is notable. I will probably now leave the machine set at risetime=2 & not revert back to 3.

http://www.internetage.ws/cpapdata/dsm- ... 5dec08.pdf


Actually, I believe this test & my observations are now providing me with a better understanding of why the Vpap AdaptSV has few adjustments and why I find I sleep lighter with the Vpap AdaptSV than with the Bipap AutoSV. Until convinced otherwise I now believe the Vpap AdaptSV targets for a lower CO2 retention at the expense of depth of sleep vs the Bipap AutoSV which can be tuned to perform well or perform badly depending on the expertise of the person setting the machine up.

If what I am seeing is correct, then I am now leaning to the view that the Bipap AutoSV may do more harm than good if people play with it without targeting the CO2 retention issue. And, as we know, that is a difficult enough matter for those in the profession let alone us wild-eyed dial-wingers.

DSM

#2

It does intrigue me that the better night shows less air
i.e.
Night 1 av peak flow = 45.4 Tidal flow = 603
Night 2 av peak flow = 43.4 Tidal flow = 583

Why would speeding up risetime result in lowered total air ???

dsm wrote:us wild-eyed dial-winger

a.k.a. "the SDB occult" ... at least in medical white papers like the one above.

-SWS wrote:Excellent point about the French-to-English translator probably having mistranslated. Here's my best guess about that meaning or translation:

occult SDB = obscured SDB = undiagnosed SDB

But even members of the occult surely must get SDB... Very seriously, thanks for the article, Doug!

on edit: I think occult is a genuine medical term in English.

# Hidden from view; concealed.
#

1. Medicine. Detectable only by microscopic examination or chemical analysis, as a minute blood sample.
2. Not accompanied by readily detectable signs or symptoms: occult carcinoma.

http://www.answers.com/occult

I would go for the translator being sloppy or lazy & taking nocturnal (nocturne) to mean occult.

DSM

I vote for medicalese
http://dictionary.reference.com/browse/occult

–adjective 1. of or pertaining to magic, astrology, or any system claiming use or knowledge of secret or supernatural powers or agencies.
2. beyond the range of ordinary knowledge or understanding; mysterious.
3. secret; disclosed or communicated only to the initiated.
4. hidden from view.
5. (in early science)

• a. not apparent on mere inspection but discoverable by experimentation.
  b. of a nature not understood, as physical qualities.
  c. dealing with such qualities; experimental: occult science.

6. Medicine/Medical. present in amounts too small to be visible: a chemical test to detect occult blood in the stool.

But I love the term "practicing occult sleep apnea"

Any chance that the long large leak on the second nigh affected the measurements? The response to a large leak is controlled by the autotrak alogrithm - and that one is used on the SV as well.

[quote ="Respironic's when descirbing an auto functining"]A leak is detected when Baseline Flow increases to more than 2 times the expected leak.

This increased flow is considered to be in large leak if the threshold is exceeded for more than 1.5 minutes.

The REMstar Auto system responds to the large leak by dropping the pressure 1 cmH20 every two minutes until the large leak condition is cleared. As the pressure is dropped, the expected leak also drops.[/quote]


You can see how the drop in the peak flow corresponds exactly to the "large leak" as identified by that black bar. Could it be that on a flow controlled machine, the response to a large leak is a drop in flow?

O.

dsm wrote:Re the headache, this may be due to CO2 retention. I am finding as I get to know my Bipap AutoSV more, that I can get great data but still begin to hit periods of drowsiness and can predictably bump up the risetime (from 3 to 2) to clear these.

Doug, I think your on to something here. I left my settings the same last night but bumped risetime from 3 to 2. My AHI actually was a bit worse (2.1) but I feel way better today than I did yesterday. I think I will run at these settings again tonight.

How exactly does a faster rise time reduce CO2 retention?

dsm wrote:Re the headache, this may be due to CO2 retention. I am finding as I get to know my Bipap AutoSV more, that I can get great data but still begin to hit periods of drowsiness and can predictably bump up the risetime (from 3 to 2) to clear these.

Short rise times also result in less neuromuscular work of breathing or WOB. But those potential benefits can only occur providing that short rise times don't induce discomfort-related asynchrony (i.e. poor BiLevel timing that can sometimes be induced between patient and machine). I agree that transient CO2 issues sound like a definite possibility to consider as well. However, I haven't yet discovered literature or research relating to early-inspiration machine pressure-slope influencing CO2 retention. Understandably there is plenty of literature about expiratory phase CO2 being re-breathed to elevate or bias CO2 in the blood stream---as compensation for hypocapnic apneas typically associated with CSDB. In that CSDB treatment case highly-convenient and CO2-laden exhalation is simply made available via enhanced expiratory re-breathing space (EERS therapy). That reused or re-breathed CO2 is then infused into the bloodstream during inspiration, to intentionally create slightly higher CO2 levels than usual. That CO2 upward-biasing, in turn, compensates the CSDB patient's chemoreceptors that are associated with the malfunctioning inspiratory signal or trigger. In general, the human signal or trigger to inhale is based largely on detecting just the right CO2 threshold in the bloodstream (detected via ever-fluctuating pH levels at central chemoreceptors in the brain).

Anyway, Doug, aside from CO2 I also wonder about the possibility that excessive airway inflammation might episodically occur in your case. And that an intermittently heightened airway impedance just may create too much neuromuscular work of breathing (WOB) for restful sleep. If so, the heightened neuromuscular work of breathing (WOB) might theoretically generate more sleep arousals known as RERAs (more than usual for you). And since shorter rise times are known to decrease WOB, those decreased rise times just might be nicely compensating for any sleep-disturbing RERA spikes you may intermittently experience (based on episodic airway inflammation/impedance issues). Or perhaps diminishing RERA's may not come into play as WOB is decreased via shorter rise times. Perhaps the tiredness issue simply has to do with the extra neuromuscular workload that heightened airway impedance imposes throughout an entire night of sleep. I remember reading literature claiming that COPD patients can sleep poorly and be fatigued during the day because of heightened neuromuscular WOB during flareups.

James, If it turns out that you also find shorter rise times advantageous, then I would start to wonder if your somewhat unusual airway impedance problem (related to WOB) is perhaps better compensated with those shorter rise times. Shorter BiLevel rise times and heightened PS both happen to decrease WOB. However, I suppose it's conceivable that shorter rise times just may be the less disruptive of those two WOB-improving factors for any given CSDB patient.

-SWS wrote:

dsm wrote:Re the headache, this may be due to CO2 retention. I am finding as I get to know my Bipap AutoSV more, that I can get great data but still begin to hit periods of drowsiness and can predictably bump up the risetime (from 3 to 2) to clear these.

Short rise times also result in less neuromuscular work of breathing or WOB. But those potential benefits can only occur providing that short rise times don't induce discomfort-related asynchrony (i.e. poor BiLevel timing that can sometimes be induced between patient and machine). I agree that transient CO2 issues sound like a definite possibility to consider as well. However, I haven't yet discovered literature or research relating to early-inspiration machine pressure-slope influencing CO2 retention. Understandably there is plenty of literature about expiratory phase CO2 being re-breathed to elevate or bias CO2 in the blood stream---as compensation for hypocapnic apneas typically associated with CSDB. In that CSDB treatment case highly-convenient and CO2-laden exhalation is simply made available via enhanced expiratory re-breathing space (EERS therapy). That reused or re-breathed CO2 is then infused into the bloodstream during inspiration, to intentionally create slightly higher CO2 levels than usual. That CO2 upward-biasing, in turn, compensates the CSDB patient's chemoreceptors that are associated with the malfunctioning inspiratory signal or trigger. In general, the human signal or trigger to inhale is based largely on detecting just the right CO2 threshold in the bloodstream (detected via ever-fluctuating pH levels at central chemoreceptors in the brain).

Anyway, Doug, aside from CO2 I also wonder about the possibility that excessive airway inflammation might episodically occur in your case. And that an intermittently heightened airway impedance just may create too much neuromuscular work of breathing (WOB) for restful sleep. If so, the heightened neuromuscular work of breathing (WOB) might theoretically generate more sleep arousals known as RERAs (more than usual for you). And since shorter rise times are known to decrease WOB, those decreased rise times just might be nicely compensating for any sleep-disturbing RERA spikes you may intermittently experience (based on episodic airway inflammation/impedance issues). Or perhaps diminishing RERA's may not come into play as WOB is decreased via shorter rise times. Perhaps the tiredness issue simply has to do with the extra neuromuscular workload that heightened airway impedance imposes throughout an entire night of sleep. I remember reading literature claiming that COPD patients can sleep poorly and be fatigued during the day because of heightened neuromuscular WOB during flareups.

James, If it turns out that you also find shorter rise times advantageous, then I would start to wonder if your somewhat unusual airway impedance problem (related to WOB) is perhaps better compensated with those shorter rise times. Shorter BiLevel rise times and heightened PS both happen to decrease WOB. However, I suppose it's conceivable that shorter rise times just may be the less disruptive of those two WOB-improving factors for any given CSDB patient.

SWS,

Just located this post & it makes insightful reading. Last weekend went away to a holiday beach & did walks each morning & some swimming etc: - past 2 nights have slept like a log - deep restful sleep. Have put that down to all the relaxation & exercise.

James,
Am interested as to how you find changing risetime. What I see it doing is 2 things (just looking logically)
1) faster risetime should mean more air gets delivered per breath (although the av peak flow & tidal data often says otherwise ?)
2) as SWS says, faster risetime makes it easier to breathe - less effort
2) my thinking re CO2 is that a faster risetime would increase respiration volume and theoretically reduce CO2 retention (but am really flying a kite on this theory). Partly I am influenced by the way the Vpap Adapt SV seems to drive very fast risetime & it has a specific design goal of controlling CO2 retention esp for Periodic Breathing patterns.

Perhaps SAG might be willing to comment re the effects of risetime variation - his input would be very helpful. To repeat my own observations, I understand the Vpap Adapt SV specifically works to a lower level of CO2 retention. But the Bipap Auto SV being manually adjustable, means we users can change that behavior.

DSM

Doug, continued headaches would keep CO2 on my suspect list as well. So I think your CO2 point was a very good one.

Desats are a possibility as well, for continued headaches.