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Sleep Apnea, Snoring, Narcolepsy,
Insomnia and Other Sleep Disorders.



Understanding the symptoms of sleep disorders.




Central Sleep Apnea: Treatment With Adaptive Servo-Ventilation (ASV).

What about long-term effects and benefits of adaptive servo-ventilation (ASV)?

ASV became available in the United States in 2006. However, it has been in use for longer periods of time in both Europe and Canada, where it is known as the ResMed Autoset CS2.

I received an e mail from a Canadian patient about his experience prior to and since beginning use of this remarkable new device and with his permission, I reproduce our correspondence here.

On Nov 21, 2006, at 12:41 AM, Ernie Buhr wrote:

Attention Dr. Robert W. Clark:

I am a CSA/CSR patient and have been using the ResMed Autoset CS2 machine with great success since May 14, 2005, the luckiest day of my life.  Today I found some interesting material on the internet from the Columbus Community Health Regional Sleep Disorders Center, referring to the revolutionary new treatment Adaptive Servo-Ventilation.

Your recent press release includes a testimonial from patient "Evan", the most intriguing aspect being that it echoes almost word for word my own statements, substituting only "Dr. Robert Clark" for "Dr. Meir Kryger".  But beyond that, reference is made to your ASV machine as "ResMed VPAP Adapt SV".  The description of its operation seems identical to "ResMed Autoset CS2".

My question is, are these in fact the same machine with yours perhaps just having an updated name?  If not, has there been an actual upgrading of the machine operationally?  I would really appreciate hearing from you, and might add I would be most happy to expand on my own story in the event there is any interest in further testimonials from a longer term user, now at 18 months.

Keep up the good work, and many thanks for what you do for people such as myself who suffer from a low profile but unfortunately extremely debilitating condition when untreated.

Ernie  Buhr


From: "Robert W. Clark MD"
To: Ernie Buhr
Subject: Re: Adaptive Servo-Ventilation
Date: Wed, 22 Nov 2006 10:43:13 -0500

Ernie, I checked and learned that the Autoset CS2 is the name for the VPAP Adapt SV in Canada and Europe.  You have had it far longer than have we.  It is a phenomenally exciting and effective device and I am delighted that you have done so well.

Could you expand on your own story?  I think that it could be very helpful to others to learn that the benefits do not lessen over time, and we obviously have limited experience with it in the US.  We still are the only sleep center in this region to have it on site,and we obtained our first unit this summer.

-Dr. Clark


Doctor Clark:

Thank you very much for your reply.

I'm 61 years old, and was first diagnosed with a sleep disorder in late 1996 after quite innocently making a comment to my family physician in June of that year (something about falling asleep at a red light).  That got his attention, resulting in a sleep study being performed a few months later.  My apnea index then was 19 per hour.  I was not a snorer, and not particularly overweight.  CPAP therapy was tested but seemed not to be of much help.  Nasal surgery was performed (septoplasty and turbinectomy), which while improving some minor chronic breathing difficulties did nothing to reduce the apnea.  Nor did a later attempt to control the issue with a dental appliance.  My specialist, Dr. Meir Kryger, indicated the problem was primarily central apnea, with some obstructive component.

Nocturnal oxygen was prescribed, beginning in December, 1997 at 1 1/2  litres/minute and delivered by means of an oxygen concentrator.  This was initially quite effective, subsequently being increased in dosage to 2 and then 2 1/2  l/m.  I continued to work at my occupation, employee benefits insurance consulting and sales management.  Increasingly, however, my energy levels were falling, to the point I withdrew from most all of a previously very active personal life.  Activities, both mental and physical, which formerly were performed from a natural energy source became more and more difficult.  But I was functioning.

In or about spring 2003, I noticed a pronounced and rapid regression in how I felt as well as in my concentration.  My initial reaction was to attribute this to years of dealing with sleep deprivation, increasing age, and an intense work environment.  It was finally catching up to me.  But I also thought the extent and suddenness of the change were too great to be only that.  Dr. Kryger suggested and I agreed to trying modafinil as an agent to counteract the sleepiness.  I did so beginning in September, 2003, first on a periodic "as needed" basis, graduating to regular daily usage in January, 2004.

In March, 2004 another lab test was performed, with results confirming my fears.  Without oxygen I had 84.2 abnormal breathing events per hour, which were primarily central sleep apnea.  On oxygen the events decreased to 45.3 per hour.  In a letter to my family physician Dr. Kryger said my "periodic breathing is puzzling since we don't have an etiology for it".  As an aside to the whole issue of daytime sleepiness, he told me at the time he "would not be surprised to hear one day that you are in the hospital and the doctors are trying to get your heart rate under control".  How prophetic.

I took the month of March, 2004 off work, somehow hoping the "rest" would help stabilize the now almost unmanageable consequences of no sleep, and related emotional / cognitive / concentration distress, apparently exacerbated by modafinil (although it certainly did have the effect of overriding the body's natural fatigue mechanism).  Unfortunately whatever little impact this sabbatical did have was limited only to the actual time away, when I could and did doze off on demand.  But beyond that I experienced no noticeable improvement in how I felt or in my energy levels.

I struggled to hide a growing inability to concentrate and with severe and embarrassing loss of memory.  My personal and general family life (I have 4 children and 7 grandchildren, all of whom live very close) was miserable, although I shared that only with two or three of my closest friends. On May 7th, my family physician recommended strongly that I leave the workforce, and in the absence of some then as yet unknown cure or therapy developing, I likely could not expect to return.  In other words, my whole identity as I looked at it then was being stripped away.  So I ignored the advice and carried on.  A major and disturbing incident which occurred Sunday June 20th, when I totally lost track of where I was and what I was doing there for perhaps a half hour, had me back to see my doctor two days later.  I have not worked since June 22, 2004.

Continuing with modafinil as the only way to function at all, I began having more and more noticeable incidents of irregular and rapid heart rhythm, atrial fibrillations.  These would frequently go on for as long as 24 hours.  On February 25, 2005 a more serious incident occurred and I attended at a hospital emergency in great distress.  Unsuccessful attempts to restore sinus rhythm with drug therapy were followed by electro cardioversion. I was released in 2 days.  The treating cardiologist's response to my history was to say "Modafinil is undoubtedly implicated in this" and to suggest I cease taking it.  The elimination of modafinil took a huge amount of stress off my system and resulted in great improvement in my emotional stability.  But naturally the symptoms of excessive daytime sleepiness increased dramatically.

On March 16th it was back to hospital emergency at a different location, with successful drug treatment involving an overnight stay.  I was told I was very fortunate to not already have had a serious stroke.  March 18th/19th brought on another major incident of atrial fibrillations, so back to emergency once again.  This time drugs were not successful, and the treating cardiologist speculated I would likely (sooner than later), go into a state of permanent atrial fib.  He also prescribed some cardiac medications.

Thus I had come to a point where sleep specialist Dr. Kryger was unable to give me any hope, and my family physician believed I would never work again.  I felt terrible, and worst of all I had become useless.  I couldn't go to movies, read the newspapers, socialize with friends, stay awake at the symphony, or do any of the usual daily activities which most people take for granted.  In truth my quality of life was at rock bottom, I really did not know how I could go on, and probably wouldn't have without a strong faith.  My own prayer and that of many others on my behalf was for a miracle.  Somehow I actually had a notion there was a solution just around the corner, and as corny as this may sound it gave me resolve to not give up even in the face of apparent absence of hope.

In that latter time frame, probably late 2004, I learned that a new machine (AutoSet CS2 - [adaptive servo-ventilation]) had been developed which Dr. Kryger wanted to test on me.  To my understanding, there was only one such machine in Canada at the time and none in the U.S. Eventually it arrived in Winnipeg, an overnight sleep study was done, and Dr. Kryger reported to my family physician as follows:

"The machine worked exactly as advertised.  When he had a Cheyne-Stokes breathing pattern the machine evidentially stabilized his ventilation and when he slept, his apnea/hypopnea index was zero.  He spent no time below an SaO2 of 90%.  He had a very large amount of REM sleep (36.3%) indicating that he had REM rebound.  His arousal index was only 8.4".

I knew from my own simple observation what the result was.  I could feel it.  In the morning I experienced what I described at the time as a sense of severe jet lag.  Initially that concerned me, but it was explained and it seemed very logical that my body was reacting to the adjustment necessary after months and years of no sleep, to now suddenly cycling normally through all stages of sleep.

In any case and as I said in my earlier email, I was later provided with a machine for home use, commencing May 14, 2005, the luckiest day of my life.  I haven't missed a night since.  Right from the beginning I felt like I had new life.  For some time thereafter I estimated that I probably was 75% rested, which I also said was likely as good as anyone my age.  But it got even better, stabilizing at somewhere around the 6-9 month stage.  Today, and for the last year, I have absolutely no symptoms of sleep deprivation.  I can and do drive my car for 10 hour days without so much as a minute of fatigue.  Now my wife tires first of travel and it is for her that we keep the driving days shorter.

I go to movies and stay awake.  I remember them for more than one day.  I shovel snow.  I send long rambling emails such as this.  I participate in family get togethers.  I don't dread nights.  I very quickly regained my long term memory, an attribute I was once known for but feared I had lost (the last two years prior to receiving ASV treatment remain as what I call a "black hole", I speculate because you can't access information not logged in to begin with and I certainly wasn't registering much in that timeframe).

I thank God every day for his incredible blessings provided through medical science and specifically practitioners such as Dr. Meir Kryger and yourself.  It is indeed a "Wonderful Life", with the only problem being I am now unbelievably bored with retirement and the soft, easy (lazy) times I once thought would be so great.

Adaptive Servo-Ventilation is as comfortable, tolerable, subtle and dramatically effective as claimed.  "Praise God From Whom All Blessings Flow".

If you should ever have a patient who just wants to talk to someone who has been through this, I would be glad to oblige. 

Ernie  Buhr

Click here to request contact information for Mr. Buhr.

Click here to listen to a WSNY-FM radio interview with Dr. Clark about adaptive servo-ventilation.


Columbus, Ohio, Central Ohio, hospitalssleep, wake, insomnia, sleepiness 

Accredited by the American Academy of Sleep Medicine.

Robert W. Clark, M.D., Medical Director
1430 South High Street, Columbus OH 43207

Tel: [614] 443-7800
Fax: [614] 443-6960


 © Copyright 2006 Robert W. Clark M.D. Inc.