My wife said I snore, but I never hear it.  My kids hate to share a hotel room with me because they say I snore, but again, I never hear it.  I fall asleep quickly at night, but wake up all night long.  Sometimes I wake up in the morning with a headache.   I’m tired throughout the day and usually take a nap at lunch.  If we are going to drive somewhere for more than an hour, I let my wife drive so I can sleep the whole way.  I took a course on sleep apnea as part of my continuing education and it felt like a Sunday morning sermon with the preacher pointing his finger directly at me!  Do I have a problem?

My son, Dr. Phillip Kraver and I began to look into sleep apnea more and learned about the diagnosis and treatment of obstructive sleep apnea.  I already had been making anti-snoring devices for many years in our office, but this was controversial because I didn’t know if the patients actually had obstructive sleep apnea (OSA) or not.  I would give them the sleepiness test that was supplied by Glidewell Dental Labs, and it never dawned on me that I should have taken it myself!

The Epworth Sleepiness Scale

In the patient’s typical daily life, how likely are they to doze off or fall asleep in the following situations (not  just feeling tired)?  Use the following scale to choose the most appropriate number for the situation:

0 = Would never doze

1 = Slight chance of dozing

2 = Moderate chance of dozing

3 = High chance of dozing

  • Sitting and reading
  • Watching Television
  • Sitting, inactive, in a public place (theatre, meeting, etc.)
  • As a passenger in a car for an hour without a break
  • Lying down to rest in the afternoon when circumstances permit
  • Sitting and talking to someone
  • In a car, while stopped for a few minutes in traffic
  • Sitting quietly after lunch without alcohol
  • Driving a car or truck for two (2) hours or more

Epworth Scoring:

  • Score of 1-6: you’re getting enough sleep
  • Score of 4-8: you tend to be sleepy during the day; this is the average score
  • Score of 9-15: you are very sleepy and should seek medical advice
  • Score of 16 or greater: you are dangerously sleepy and should seek medical advice
My score was 13! :-( Just think, if I read boring books or watched QVC on the TV I could have had a much higher score!
Another interesting questionnaire is from David P. White, M.D., Professor of Sleep Medicine at Harvard Medical School.
  • Snoring: Do you snore on most night (>3 times per week)? Yes=2, No=0 Is your snoring loud (heard through doors and walls)? Yes =2, No=0
  • Sleep Noises: Has it ever been reported to you that you stop breathing or gasp in your sleep? Never=0, Occasionally=3, Frequently=5
  • Collar size:  What is your collar size? Male <17 inches=0, Male >17 inches=5; Females <16 inches=0, Females >16 inches=5
  • Daytime Sleepiness: Do you occasionally fall asleep during the day when: Busy or active? No=0, Yes=2; Driving or stopped at a light? No=0, Yes=2
  • Hypertension: Have you ever had or are you being treated for high blood pressure? No=0, Yes=1
Scoring:
  • 5 or less has allow incidence for sleep related disorder
  • 6-8 you need to speak with your physician
  • Greater than 8 has a high probability for sleep related disorders and you should seek medic advice.
My score was 8 :-(

We attended a seminar by Dr. John Tucker on Obstructive Sleep Apnea (OSA) and at the meeting they had a vender who was trying to sell one of those expensive home sleep study instruments. It measured everything from PaO₂(blood oxygen levels), actigraphy (body movements), sleep positions, levels of sleep (wake, light sleep, deep sleep and REM), heart rate, snoring loudness in decibels to peripheral arterial tone which mirrored your autonomic nervous system. WOW!  They let me wear one over night in the hotel and the results were sobering.  I just thought I snored like everyone else, but instead the study suggested I had sleep apnea!

Where do you turn when you think you are having a problem with sleep apnea?  I asked my physician at my last check-up about sleep apnea.  He really couldn’t do anything about it and then renewed my prescription for sleeping pills, high cholesterol, gastroesophageal reflux (GERD) and high blood pressure. He then added to my normal blood work-up HgA1C which everyone knows is a test for diabetes.  Bummer.  He did give me a referral to see a pulmonologist with the associated diagnosis code of sleep apnea [780.57C], which I felt was a step in the right direction.  My physician told me he could not order any kind of formal sleep study himself and I was now in the hands of the pulmonologist.  If the pulmonary doctor ordered a sleep study, I would then have to go to a nearby sleep center and sleep there all night with all kinds of equipment hooked up to me to monitor my sleeping patterns.  To tell you the truth, I was a little intimidated about going to a sleep center at a strange place with strangers watching my every movement while I slept or tried to sleep.  I’d much rather bring the sleep test home to my own bed, if I could.  Furthermore, I really liked knowing that I had a problem before I commit to a full blown sleep study at some strange center away from the privacy and comfort of my own bed and that home sleep study did it for me. Everyone including the sleep doctors know it is very inconvenient to have a formal sleep study done, but this is the most reliable way to obtain an Apnea/Hypopnea Index or commonly known throughout the sleep world as your AHI.  AHI is an index used to assess the severity of OSA based on the total number of non-breathing events (apnea) and partial breathing event (hypopnea) which occurring per hour of sleep.  Measured pauses in breathing (greater than 10 seconds) are associated with a decrease in oxygenation of the blood and are counted up and placed into classifications of severity (mild 5-15, moderate 15-30, and severe greater than 30).  My home sleep study had an AHI of 27 (moderately severe), now it was time to see what a formal sleep study told us.
The next step was to meet with my pulmonologist.  He was located in your typical building business complex with your typical little generic doctors office suite.  You registered with the front desk giving them all of your information, drivers license and insurance card.  Before you go back to see the doctor you get your height, weight, blood pressure, pulse oximeter reading and neck size.  Neck size?  Yes, apparently there are studies that correlate how thick your neck is with OSA (men ≧17 and women ≧16 inches).
I met the doctor and he listened to my story.  I told him about my sleepiness, my mild hypertension, my cholesterol, GERD, dry cough, and elevated glucose levels.  He listened to my chest and recommended I have a sleep study.  Simple as that.

I showed up 8pm on a Friday night at Cape Coral Hospital’s ER to check in for my over night sleep study.  My wife came along to take pictures, tuck me in and bring cookies for the technician(s).  The room was nice, but the bed and pillows were uncomfortable.  You would think that they would have the most comfortable bed in the world for you to sleep in, after all, they do want you to sleep.  Before bed, you go into the set-up room where I was hooked up to an electroencephalogram, electrocardiogram, electromyogram, nasal cannula monitor, chest and abdominal breathing straps, leg activity monitor and a positional monitor.  Wires, wires and more wires!  And that tape under the nose to hold the nasal cannula in place was the worse!  Needless to say I couldn’t sleep a wink.  Every time I rolled over something was poking into me or coming undone.  And going to the bathroom was such an ordeal it is a wonder anyone could sleep after that.  I just hoped I didn’t have to repeat the test to get my results.

I normally get up pretty early, but here you have to stay for the allotted amount of time or you have to sign a wavier to leave early.  After lying in bed for another hour waiting for my allotted time to pass the nice sleep tech came in and made me fill out a 4 page questionnaire.  Really, 4 pages!  I suggested a better bed, pillow and to get rid of that constant buzzing of the nasal cannula pump (I’m sure I wasn’t the first to complain about my stay).
I revisited with my pulmonary doctor 2 weeks later and again they took height (like maybe that had changed since I’d seen them last), weight, blood pressure and pulse oximeter. The doctor came in and read my report. He said I had an AHI of 27 (exactly what my home sleep test said) and on cue prescribed me CPAP.
The current gold standard for treating OSA is with a mechanical respiratory device called Continuous Positive Airway Pressure (CPAP).  It is medicine’s big gun for OSA.  If you are diagnosed with OSA, then BAM, big gun, CPAP.  This to me didn’t make any sense.  When I have a patient with an infection, I don’t reach for the $1000 per pill latest and greatest most powerful antibiotic.  No, instead I use penicillin which you can get free at Publix.  Then if that didn’t work I move onto something different until if everything else doesn’t work, big gun.  So why doesn’t medicine do that with OSA?  One reason is that there were no simple convenient alternatives to CPAP.  Oh, and the insurance companies paid for it.  But now there is another treatment option that is easier to use and it is called Oral Appliance Therapy (OAT).
Oral Appliance Therapy (OAT):
Remember when Cardiopulmonary Resuscitation (CPR) had the ABC acronym which stood for Airway, Breathing, Cardiac?  Now it is CAB, but my point is that to open the airway you were instructed to simply lift the chin and the back of the throat would open up. That is the basic premise of how OAT works.  An appliance is custom manufactured for the mouth in a slightly open and forward position that prevents the lower jaw from falling backwards at night closing off the airway.  Simple and comfortable to wear.  I asked my sleep doctor to prescribe me an OAT so I would not have to endure the CPAP hose in my nose for the rest of my life.
Why do we have to worry about Obstructive Sleep Apnea?
Why do we breath in the first place?  The body is a very complex biological system that works by providing its cells with food.  This food is eaten and digested, then metabolized by using oxygen which ends up breaking down everything into carbon dioxide, water and a few other chemical byproducts.  You get rid of wastes such as carbon dioxide primarily through your lungs.  Believe it or not, but when you lose weight, you lose it through your lungs!  Oh, you do lose some through urine and sweat, but no where near as much as through the lungs in the form of carbon dioxide.  Oxygen in and carbon dioxide out.  Every biology class around the world teaches us that, but most people don’t put 2+2 together and correlate the loss of carbon dioxide with the loss of weight.  If we don’t breath properly them we cannot get oxygen into our bodies for proper bodily functions, nor can we get rid of carbon dioxide.  If we don’t have enough oxygen in our bodies our “hypoxic (low oxygen) drive” takes over and forces us to breathe.  If our hypoxic drive doesn’t work properly we can build up too much carbon dioxide in our bodies.  Too much carbon dioxide make our blood more acidic triggering our bodies to gasp for air unconsciously.  This unconscious gasping happens all night long in response to low oxygen/high carbon dioxide loads in your body.  This can cause harm throughout your organ systems including the heart and brain.  When you hear of someone dying in their sleep, it is a good bet they were snoring or unable to breath properly right before it happened. Who knows if a life could have been saved if someone just lifted their chin to help them breath at that critical moment.  It’s a mystery.

Standard of Care:

Until there is a quantum shift amongst the sleep physicians, CPAP will be the first line of treatment for OSA for the foreseeable future. BUT according to new insurance rules, patients on CPAP need to show compliance or they will have their expensive machines confiscated.  The machines actually have a counter on the inside that tells you how many times you have used it and can actually call the doctor to tell them if you are using it correctly or not.  Gone are the days you get diagnosed with OSA and are issued a CPAP machine to only let it set by your bed unused or resell it on e-bay.  Compliance amongst CPAP users is actually lower than expected since it is saving your life.  The insurance companies don’t want to pay for something not being used. Compliance is around 50%.  That means 50% are not receiving the life saving benefits of oxygenated blood all night long. This has led sleep medicine doctors to scramble for alternatives.  Oh, and those alternatives would be the dentist (where they probably should have started in the first place)  :-)

A Proposed Alternative Dental Appliance Oriented Treatment Plan for Obstructive Sleep Apnea: (not standard of care, yet)

For this hypothetical alternative treatment plan to work a close relationship between sleep medicine physicians and sleep therapy dentists needs to be established. This is how I think it should flow but it is just “my opinion, opinion, opinion” (Tuckerism).  The biggest problem with this alternative more logical plan is that there are so few dentists in the field of sleep medicine due to the obstacles of file medical insurance and Medicare.

  1. Screening for OSA – The need for screening can be recognized by either the primary care physician or the dentist.
  2. Overnight screening at home with a pulse oximeter that records data. These are relatively cheap instruments readily available at department stores or over the internet.  They don’t have to be as fancy or as expensive as the one I used at the show.  Sleep dental office should have them on hand to screen their suspected OSA patients.  Once the data is downloaded from the pulse oximeter and the numbers organized into a report, the case can be referred to a sleep physician.
  3. The data is analyzed by the sleep physician to see if a polysomnographic (sleep) study is warranted. Most over night testing facilities that do sleep studies cost a lot of money and can be cost prohibitive for many non-insured patients.  Even with insurance, it can be more than $3000 out of pocket if you have a high deductible.
  4. Polysomnogram – Once the diagnosis of OSA is established, the patient is referred to the local dental sleep dentist for manufacturing of a dental sleep appliance.
  5. Dental sleep appliance – Having the dentist make a dental sleep appliance first just makes sense.  Most of the people who will get a sleep appliance will benefit greatly from it.  Those who need more than just an appliance can then be verified with a follow-up polysomnograph with the appliance in place. If CPAP is warranted, then with the appliance in the mouth to hold the chin in the proper position the CPAP is titrated to a pressure that opens the airway (at a much lower and tolerable CPAP pressure).  This approach seems more logical and with a better outcome for the patient, but is not currently being practiced by a majority of sleep physicians around the world.
  6. CPAP – Big gun, if there is no resolution of the OSA with OAT.

References:

1. Diagnosis and Treatment of Obstructive Sleep Apnea in Adults Comparative Effectiveness Reviews, No. 32 Investigators: Ethan M Balk, MD, MPH, Denish Moorthy, MBBS, MS, Ndidiamaka O Obadan, MD, MS, Kamal Patel, MPH, MBA, Stanley Ip, MD, Mei Chung, PhD, MPH, Raveendhara R Bannuru, MD, Georgios D Kitsios, MD, PhD, Srila Sen, MA, Ramon C Iovin, PhD, James M Gaylor, BA, Carolyn D’Ambrosio, MD, MS, and Joseph Lau, MD. Tufts Evidence-based Practice Center Rockville (MD): Agency for Healthcare Research and Quality (US); July 2011. Report No.: 11-EHC052

2. Sleep Breath. 2012 Feb 26. [Epub ahead of print] The fairness of the Epworth Sleepiness Scale: two approaches to differential item functioning. Ulander MArestedt KSvanborg EJohansson PBroström A. Institution of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden, martin.ulander@liu.se.

3.  Cephalalgia. 2011 Dec 15. [Epub ahead of print] Sleep apnea headache in the general population. Kristiansen HAKværner KJAkre HOverland BSandvik LRussell MB. Head and Neck Research Group, Akershus University Hospital and Campus Akershus University Hospital, University of Oslo, Norway.

4.  Sleep. 2008 Feb;31(2):249-55. The relationship of daytime hypoxemia and nocturnal hypoxia in obstructive sleep apnea syndrome. Fanfulla FGrassi MTaurino AED’Artavilla Lupo NTrentin R. Pulmonary Division, Istituto Scientifico di Pavia, Italy. francesco.fanfulla@fsm.it

5.  Sleep Breath. 2012 Feb 10. [Epub ahead of print] Energy expenditure in obstructive sleep apnea: validation of a multiple physiological sensor for determination of sleep and wake. O’Driscoll DMTurton ARCopland JMStrauss BJHamilton GS. Department of Respiratory and Sleep Medicine, Monash Medical Centre, 246 Clayton Rd, Clayton, Victoria, 3168, Australia, denise.odriscoll@monash.edu.

6.  Sleep. 2011 Aug 1;34(8):1075-81. Quantitative effects of trunk and head position on the apnea hypopnea index in obstructivesleep apnea. van Kesteren ERvan Maanen JPHilgevoord AALaman DMde Vries N. Department of Clinical Neurophysiology, Sleep Laboratory, St. Lucas Andreas Hospital, Amsterdam, The Netherlands. e.kesteren@slaz.nl

7.  Sleep. 2011 Jan 1;34(1):73-81. The 2007 AASM recommendations for EEG electrode placement in polysomnography: impact on sleep and cortical arousal scoring. Ruehland WRO’Donoghue FJPierce RJThornton ATSingh PCopland JMStevens BRochford PD. Institute for Breathing and Sleep, Austin Health, Heidelberg, Victoria, Australia. Warren.Ruehland@austin.org.au

8. Sleep Med. 2012 Jan;13(1):21-8. Epub 2011 Nov 21. Heart rate increment in the diagnosis of obstructive sleep apnoea in an older population. Sforza EChouchou FPichot VBarthélémy JCRoche F. Service de Physiologie Clinique et de l’Exercice, CHU Nord, Saint-Etienne, Faculté de Médecine Jacques Lisfranc, PRES Université de Lyon 42023, Université Jean Monnet, Saint-Etienne, France. e.sforza@yahoo.fr

9.  Ann Biomed Eng. 2009 Sep;37(9):1807-17. Epub 2009 Jun 24. Role of upper airway dimensions in snore production: acoustical and perceptual findings. Ng AKKoh TSBaey EPuvanendran K. School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, 639798, Republic of Singapore. andrewkng@pmail.ntu.edu.sg

10 . J Clin Sleep Med. 2011 Jun 15;7(3):301-6. Sleep staging based on autonomic signals: a multi-center validation study. Hedner JWhite DPMalhotra AHerscovici SPittman SDZou DGrote LPillar G. Sleep Laboratory, Pulmonary Medicine, Sahlgrenska University Hospital, Gothenburg, Sweden.

11.  Drugs. 2009;69 Suppl 2:77-91. doi: 10.2165/11532000-000000000-00000. Can improving sleep influence sleep-disordered breathing? Sériès FWorkshop ParticipantsCollaborators (12) Centre de Pneumologie Institut Universitaire de Cardiologie et de Pneumologie de Québec, Québec, Canada. Frederic.series@med.ulaval.ca

12.  Angiology. 2012 Jan 20. [Epub ahead of print] Size and Subclasses of Low-Density Lipoproteins in Patients With Obstructive Sleep Apnea. Sopkova ZBerneis KRizzo MSpinas GADorkova ZTisko RTkacova R. Department of Respiratory Medicine and Tuberculosis, Faculty of Medicine, P.J. Safarik University and L. Pasteur University Hospital, Kosice, Slovakia.

13.  Int J Pediatr Otorhinolaryngol. 2011 Mar 3. [Epub ahead of print] Obstructive hypopnea and gastroesophageal reflux as factors associated with residual obstructive sleep apnea syndrome. Wasilewska JKaczmarski MDebkowska K. Department of Paediatrics, Gastroenterology and Allergology, Medical University of Bialystok, Waszyngtona Street 17, 15-274 Bialystok, Poland.

14.  Conf Proc IEEE Eng Med Biol Soc. 2011 Aug;2011:3209-12. Concurrent variations of cerebral blood flow and arterial blood pressure in simulated sleep apnea. Alex RBhave GAl-Abed MABashaboyina AIyer SWatenpaugh DEZhang RBehbehani K.

15.  Diabetes Technol Ther. 2011 Sep;13(9):945-9. Epub 2011 Jun 29. Effects of sleep apnea severity on glycemic control in patients with type 2 diabetes prior to continuous positive airway pressure treatment. Pillai AWarren GGunathilake WIdris I. Sherwood Forest Hospitals Foundation Trust, Sutton in Ashfield, United Kingdom.

16.  Nurs Times. 2011 Oct 11-17;107(40):31-2. Obstructive sleep apnoea: its link with diabetes. Hicks D. Enfield Community Services, Barnet, Enfield and Haringey Mental Health Trust.

17.  Braz J Otorhinolaryngol. 2011 Jul-Aug;77(4):516-21. Anthropometric data as predictors of Obstructive Sleep Apnea Severity. [Article in English, Portuguese] Pinto JAGodoy LBMarquis VWSonego TBLeal Cde FArtico MS. Hospital e Maternidade São Camilo, São Camilo Hospital and Maternity, Pompéia Núcleo de Otorrinolaringologia e Cirurgia de Cabeça e Pescoço de São Paulo, São Paulo. japorl@uol.com.br

18.  Sleep. 2004 Sep 15;27(6):1171-9. Comparison of limited monitoring using a nasal-cannula flow signal to full polysomnography in sleep-disordered breathing. Ayappa INorman RGSuryadevara MRapoport DM. NYU School of Medicine, New York 10016, USA.

19. J Sleep Res. 2011 Mar;20(1 Pt 2):201-6. doi: 10.1111/j.1365-2869.2010.00859.x. Sleep efficiency during sleep studies: results of a prospective study comparing home-based and in-hospital polysomnography. Bruyneel MSanida CArt GLibert WCuvelier LPaesmans MSergysels RNinane V. Chest Service, Saint-Pierre University Hospital, Brussels, Belgium. marie_bruyneel@stpierre-bru.be
20.  Chest. 1993 Sep;104(3):781-7. A cause of excessive daytime sleepiness. The upper airway resistance syndrome. Guilleminault CStoohs RClerk ACetel MMaistros P. Stanford University Sleep Disorders Clinic and Research Center, Stanford University School of Medicine, Stanford, Calif.
21. Am Rev Respir Dis. 1993 Jan;147(1):50-3. A comparison of clinical assessment and home oximetry in the diagnosis of obstructive sleep apnea. Gyulay SOlson LGHensley MJKing MTAllen KMSaunders NA. Sleep Disorders Centre, Royal Newcastle Hospital, South Wales, Australia.
22.  Sleep. 1995 Apr;18(3):167-71. Nocturnal oximetry: is it a screening tool for sleep disorders? Yamashiro YKryger MH.Department of Respiratory Medicine, University of Manitoba, Canada.
23.  Thorax. 1999 Nov;54(11):968-71. Nocturnal oximetry for the diagnosis of the sleep apnoea hypopnoea syndrome: a method to reduce the number of polysomnographies? Chiner ESignes-Costa JArriero JMMarco JFuentes ISergado A. Sección de Neumología, Hospital Universitario San Juan de Alicante, Carretera Alicante-Valencia s/n, 03550 San Juan de Alicante, Spain.
24.  Chest. 1996 Feb;109(2):395.9. Accuracy of oximetry for detection of respiratory disturbances in sleep apnea syndrome. Lévy PPépin JLDeschaux-Blanc CParamelle BBrambilla C. Department of Respiratory Medicine, AGIR, Home Care Regional Association for Respiratory Insufficiency, Grenoble, France.
25.  Respir Med. 2000 Sep;94(9):895-9. Which derivative from overnight oximetry best predicts symptomatic response to nasal continuous positive airway pressure in patients with obstructive sleep apnea? Choi SBennett LSMullins RDavies RJStradling JR. Osler Chest Unit and University of Oxford, Churchill Hospital, Oxford Radcliffe Trust, UK.
26.  Sleep. 1999 Feb 1;22(1):105-11. Validity of neural network in sleep apnea. el-Solh AAMador MJTen-Brock EShucard DWAbul-Khoudoud MGrant BJ. Department of Medicine and Neurology, State University of New York at Buffalo, School of Medicine and Biomedical Sciences, USA.
27.  Am J Respir Crit Care Med. 1994 Nov;150(5 Pt 1):1279-85. Likelihood ratios for a sleep apnea clinical prediction rule. Flemons WWWhitelaw WABrant RRemmers JE. Department of Medicine, Foothills Hospital, Calgary, Alberta, Canada.
28.  JAMA. 2000 Apr 12;283(14):1829-36. Association of sleep-disordered breathing, sleep apnea, and hypertension in a large community-based study. Sleep Heart Health Study. Nieto FJYoung TBLind BKShahar ESamet JMRedline SD’Agostino RBNewman ABLebowitz MDPickering TG. Department of Epidemiology, Johns Hopkins School of Hygiene and Public Health, The Johns Hopkins University, Baltimore, MD 21205, USA.
29.   N Engl J Med. 2000 May 11;342(19):1378-84. Prospective study of the association between sleep-disordered breathing and hypertension. Peppard PEYoung TPalta MSkatrud J. Department of Preventive Medicine, University of Wisconsin School of Medicine, Madison 53705, USA. ppeppard@facstaff.wisc.edu
30.  Am J Respir Crit Care Med. 2001 Jan;163(1):19-25. Sleep-disordered breathing and cardiovascular disease: cross-sectional results of the Sleep Heart Health Study. Shahar EWhitney CWRedline SLee ETNewman ABJavier Nieto FO’Connor GTBoland LLSchwartz JESamet JM. Division of Epidemiology, School of Public Health, University of Minnesota, Minneapolis, Minnesota, USA.
31.  J Sleep Res. 1999 Mar;8(1):51-5. Prediction of sleep-disordered breathing by unattended overnight oximetry. Olson LGAmbrogetti AGyulay SG. Discipline of Medicine, University of Newcastle, NSW, Australia. lolson@mail.newcastle.edu.au
32.  Thorax. 2000 Apr;55(4):302-7. Automated analysis of digital oximetry in the diagnosis of obstructive sleep apnea. Vázquez JCTsai WHFlemons WWMasuda ABrant RHajduk EWhitelaw WARemmers JE. Division of Respiratory Medicine, Department of Medicine, University of Calgary, Calgary, Alberta, Canada T2N 4N1.
33.  Sleep. 1997 Nov;20(11):991-1001. Automated detection and classification of sleep-disordered breathing from conventional polysomnography data. Taha BHDempsey JAWeber SMBadr MSSkatrud JBYoung TBJacques AJSeow KC. Department of Preventive Medicine, University of Wisconsin-Madison 53705, USA.
34.  JAMA. 2000 Apr 12;283(14):1829-36. Association of sleep-disordered breathing, sleep apnea, and hypertension in a large community-based study. Sleep Heart Health Study. Nieto FJYoung TBLind BKShahar ESamet JMRedline SD’Agostino RBNewman ABLebowitz MDPickering TG. Department of Epidemiology, Johns Hopkins School of Hygiene and Public Health, The Johns Hopkins University, Baltimore, MD 21205, USA.
35.  N Engl J Med. 2000 May 11;342(19):1378-84. Prospective study of the association between sleep-disordered breathing and hypertension. Peppard PEYoung TPalta MSkatrud J. Department of Preventive Medicine, University of Wisconsin School of Medicine, Madison 53705, USA. ppeppard@facstaff.wisc.edu
36.  Am J Respir Crit Care Med. 2001 Jan;163(1):19-25. Sleep-disordered breathing and cardiovascular disease: cross-sectional results of the Sleep Heart Health Study. Shahar EWhitney CWRedline SLee ETNewman ABJavier Nieto FO’Connor GTBoland LLSchwartz JESamet JM. Division of Epidemiology, School of Public Health, University of Minnesota, Minneapolis, Minnesota, USA.
37.  Am J Respir Crit Care Med. 1999 Feb;159(2):461-7. Randomized placebo-controlled crossover trial of continuous positive airway pressure for mild sleep Apnea/Hypopnea syndrome. Engleman HMKingshott RNWraith PKMackay TWDeary IJDouglas NJ. Department of Respiratory Medicine, University of Edinburgh, United Kingdom.
38.  Chest. 1999 Mar;115(3):863-6. Indications for positive airway pressure treatment of adult obstructive sleep apnea patients: aconsensus statement. Loube DIGay PCStrohl KPPack AIWhite DPCollop NA. Walter Reed Army Medical Center, Washington, DC 20307-5001, USA. MAJORvDANIELvLOUBE@WRAMC1-amedd.army.mil
39.  Ann Intern Med. 2001 Jun 5;134(11):1015-23. Treatment with continuous positive airway pressure is not effective in patients with sleep apnea but no daytime sleepiness. a randomized, controlled trial. Barbé FMayoralas LRDuran JMasa JFMaimó AMontserrat JMMonasterio CBosch MLadaria ARubio MRubio RMedinas MHernandez L,Vidal SDouglas NJAgustí AG. Servei de Pneumologia, Hospital Universitari Son Dureta, Andrea Doria, 55, 07014 Palma de Mallorca, Spain.
40.  Am J Respir Crit Care Med. 2001 Sep 15;164(6):939-43. Effectiveness of continuous positive airway pressure in mild sleep apnea-hypopnea syndrome. Monasterio CVidal SDuran JFerrer MCarmona CBarbé FMayos MGonzalez-Mangado NJuncadella MNavarro ABarreira RCapote F,Mayoralas LRPeces-Barba GAlonso JMontserrat JM. Serveis de Pneumologia of Ciutat Sanitària i Universitària de Bellvitge, Hospital Txagorritxu, Fundacion Jimenez Diaz, Hospital Clinic, Institut Municipal d’Investigació Mèdica, Barcelona, Spain. cmonasterio@csub.scs.es
41.  Am J Respir Crit Care Med. 1999 Jan;159(1):43-8. A comparison of apnea-hypopnea indices derived from different definitions of hypopnea. Tsai WHFlemons WWWhitelaw WARemmers JE. Division of Respiratory Medicine, Department of Medicine, University of Calgary, Calgary, Alberta, Canada.
42.  Am J Respir Crit Care Med. 2000 Feb;161(2 Pt 1):369-74. Effects of varying approaches for identifying respiratory disturbances on sleep apnea assessment. Redline SKapur VKSanders MHQuan SFGottlieb DJRapoport DMBonekat WHSmith PLKiley JPIber C. Department of Pediatrics, Case Western Reserve University, Cleveland, Ohio 44106-6003, USA. sxr15@po.cwru.edu
43.  Chest. 1993 Sep;104(3):781-7. A cause of excessive daytime sleepiness. The upper airway resistance syndrome. Guilleminault CStoohs RClerk ACetel MMaistros P. Stanford University Sleep Disorders Clinic and Research Center, Stanford University School of Medicine, Stanford, Calif.
44.  Am J Respir Crit Care Med. 2000 Oct;162(4 Pt 1):1210-4. Frequency and significance of increased upper airway resistance during sleep. Rees KKingshott RNWraith PKDouglas NJ. Sleep Center, University of Edinburgh, Royal Infirmary NHS Trust, Edinburgh, Scotland, United Kingdom.
45.  J Am Board Fam Med. 2012 Jan-Feb;25(1):104-10. Is insomnia an independent predictor of obstructive sleep apnea? Glidewell RNRoby EKOrr WC. Lynn Institute for Healthcare Research, Colorado Springs, CO 80907, USA. rglidewell@lhsi.net