J. H. Peter· T. Penzel
T. Podszus . P. von Wichert (Eds.)
Sleep
and Health Risk
With 193 Figures
Springer-Verlag
Berlin Heidelberg New York London Paris Tokyo
Hong Kong Barcelona
Priv.-Doz. Dr. JORG H. PETER Dipl.-Phys. THOMAS PENZEL Priv.-Doz. Dr. THOMAS PODSZUS Prof. Dr. PETER v. WICHERT
Klinikum der Philipps-Universitat Marburg Zentrum fUr Innere Medizin
Abteilung Poliklinik Baldinger StraBe
W-3550 Marburg, Bundesrepublik Deutschland
ISBN-13: 978-3-540-53083-1 DOl: 10.1007/978-3-642-76034-1
e-ISBN-13: 978-3-642-76034-1
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Preface
The link between what a physician sees in patients and the life processes is pathophysiology. Physiology and pathophysiology are the basis of clinical symptoms and signs; they in turn are the result of cellular and biochemical processes.
All life processes are regulated. For a long time it has been known that the regulation of physiological (or pathophysiological) processes changes depending on time, for instance heart rate or respiration during the day and at night. This was understood in the past to be more or less two sides of one coin, and the causes of these processes thought to be solely one regulating principle. It has only recently been understood that sleep itself changes the program behind the regulation, which is moreover dependent on the stage of sleep.
Regulation during sleep is not merely a mirror of those during wakfulness periods, but follows different rules. The analysis of the phenomena related to sleep has provided much new information in the past 10 years, profoundly changing our interpretation of the events occurring at night. This holds true particularly for the regulation of breathing. Work performed in the last few years has demonstrated that sleep can not only be viewed as a phase of relaxa- tion or rejuvenescence and is the most healthy period in human life;
on the contrary it has become clear that sleep may, in particular circumstances, be potentially harmful. These new insights into this very normal process are of great importance for our understanding of the regulatory mechanisms of life and behavior of man. Different studies have raised overwhelming material showing that - at least in some individuals - sleep has pathologic consequences. These new insights are based mainly on polysomnographic and epidemiologic studies done in different laboratories and countries. Because of the very complicated methodology necessary for sleep studies, these new results are not yet considered as important by the medical community. This is the reason that these problems are widely under- estimated and overlooked until now.
The sleep disturbance which is most impressive is the alteration of breathing patterns. It forms a separate pathognomonic item,
VI Preface known as sleep apnea. Not only sleep apnea but many different sleep-related breathing disorders are known to exist, forming at least an additional risk profile for people at a certain cardiovascular or respiratory risk. The sleep-related worsening of a lower airway obstruction is an important example. Sleep-related alteration of normal function may play itself a distinct role in the pathogenesis of cardiovascular and respiratory diseases as well as induce psychophy- siological complaints. It is now accepted that sleep-related breathing disorders have a profound impact on the development of arterial and pulmonary hypertension, the incidence of cardiac infarction and arrhythmias, and - according to the latest results - also traffic and work accidents.
The organizers of this symposium were therefore eagerly interested in collecting as much information as possible on the link between sleep and the health risk stemming from sleep under different conditions and in different populations. We are convinced that only an interdisciplinary approach with scientists from many different fields and specialties with a broad spectrum of views will advance research and clinical knowledge on this important topic in medicine. In this respect, the idea that sleep may constitute a health risk factor could be a milestone in the development of new diag- nostic and therapeutic methods.
This book contains the papers presented at an interdisciplinary symposium that was kindly supported by: Hessischer Minister fUr Wissenschaft und Kunst, Philipps-Universitat Marburg, Bayer AG, Bayropharm GmbH, Behringwerke, Boehringer Ingelheim KG, Boehringer Mannheim GmbH, Bristol-Myers, Byk Gulden Lomberg Chemische Fabrik, Drager Werke AG, Fresenius AG, M. Gruber GmbH, Hellige GmbH, Hoechst AG, Hoyer Medizintechnik, Hoffmann La Roche AG, Erich Jager GmbH, Dieter Lowenstein Medizin Technik, H. Mack Nachf., Madaus Medizin Elektronik, E. Merck, Mundipharma Vertriebsgesellschaft, Picker International GmbH, Radiometer Deutschland, Rohm Pharma GmbH, Schering AG, Stimotron Medizinische Gedite, Upjohn GmbH, Weinmann Gerate fUr Medizin und Arbeitsschutz, and ZAK Medizin Technik.
This book demonstrates the wide spectrum of interesting ques- tions to be worked on in the future. It will be helpful to everyone concerned with problems related to sleep and support them in their clinical work and research.
. We wish to thank Regina Klingenberg and Matthias Faust for their valuable help in organizing the symposium "Sleep and Health Risk" and for their assistance in preparing this book.
Marburg P. VON WICHERT
Contents
Part 1 Sleep and Health Risk: Methodology
The Present State of Ambulatory Monitoring of Sleep
K. KA YED (With 1 Figure) ... . . 3 Problem-Oriented Diagnosis of Sleep Disorders
Using Computerized Methods
T. PENZEL and J. H. PETER (With 4 Figures). . . 11 Computer-Assisted Polysomnography
J.R. SMITH (With 1 Figure) ... 20 Vitalog "Lunch box" Home Monitor for Evaluation
of Obstructive Sleep Apnea
L.E. MILES (With 3 Figures) ... . . 28 A Mobile Ten-Channel Unit (Sid as 2010)
for the Diagnosis of Sleep-Related Breathing Disorders H. SCHNEIDER, L. GROTE, T. PENZEL, J.H. PETER,
F.D. STOTT, and P. VON WICHERT (With 5 Figures) . . . 37 Model-Based Sleep Analysis
B. KEMP and H.A.C. KAMPHUISEN (With 4 Figures) A New Method of Electroencephalographic Analysis for the Determination of Stable and Unstable Processes
50
H.-U. BALZER and I. FIETZE (With 3 Figures) . . . 58
Part 2 Sleep and Health Risk: Epidemiology
Two-Peak 24-Hour Patterns in Sleep, Mortality, and Error
M.M. MITLER (With 5 Figures) . .. . . ... . . 65
VIII
Sleepiness in an Adult Population:
Prevalence, Validity, and Correlates W.W. SCHMIDT-NoWARA, C.L. WIGGINS,
Contents
and J .K. WALCH (With 1 Figure) .. : . . . 78
Epidemiology and Natural History of Obstructive Sleep Apnea Syndrome F. CIRIGNOTTA, G. COCCAGNA, M. PARTINEN,
R. D' ALEssANDRo, and E. LUGARESI (With 2 Figures). . . 84 Insomnia and Menopause Among Middle-Aged Women:
An Epidemiological Survey of Icelandic Women T. GISLASON, J.K. BJORNSSON, B. BENEDlKTSD6TTIR, J. GUDMUNDSSON, H. KRISTBJARNARsoN,
and B. THORLEIFSD6TTIR (With 4 Figures) .. . . 92 Symptoms and Findings in 489 Outpatients
with Suspected Sleep Apnea J.H. PETER, M. FAuST, T. PLOCH,
and B. SCHULTZE (With 9 Figures) ... 101
Long-Term Evolution of Obstructive Sleep Apnea
M. PARTINEN and C. GUILLEMINAULT . . . 108
Part 3 Sleep and Health Risk in Neurology Physiological Risks During Sleep
P.L. PARMEGGIANI . . . 119 Health Risks Associated
with Autonomic Nervous System Malfunction
C.M. SHAPIRO (With 6 Figures) . . . 124 Sleep Disturbances Caused by Rest-Dependent Muscular
and Motor Dysfunctions
H. SCHULZ and E. KISS (With 4 Figures) . . . 137 Health Risk Narcolepsy: Evidence for an Involvement
of Alpha-Adrenergic Mechanisms
B. FRUHSTORFER, E. MIGNOT, S. NISHINO, W. C. DEMENT,
and C. GUILLEMINAULT (With 2 Figures) . . . 146
Contents
Sleep-Related Respiratory Impairment in Muscular and Skeletal Diseases
G. COCCAGNA, F. CIRIGNOlTA, S. MONDlNI, M. SCHIAVlNA,
IX
and R. GERARDI (With 3 Figures) . . . 154 Ambulatory Monitoring of Sleep-Related Panic Attacks
M. GOBEL, J. MARGRAF, C.B. TAYLOR, A. EHLERS,
and W.T. ROTH (With 4 Figures) ... 161 Psychological Problems Correlated with Sleep Apnea
S. STEPHAN, W. CASSEL, F. SCHWARZENBERGER-KESPER,
I. FElT, C. HENN-KoLTER, and J.H. PETER (With 1 Figure) . . . 167 Interaction and Classification of Sleep and Health Risk
E. FOSSEY, M.F. FITZPATRICK, N.J. DOUGLAS,
and C.M. SHAPIRO. . . . 174
Part 4 Sleep and Health Risk: Breathing Disorders
Central Venous Oxygen Saturation, Abnormal Gas Exchange, and Rate of Fall of Arterial Oxyhemoglobin Saturation During Obstructive Apnea
E.C. FLETCHER (With 6 Figures) . . . 183 Advances in Respiration Acoustic Monitoring
H. PASTERKAMP (With 7 Figures). . . 193 Variability of Breathing Pattern
M.J. TOBIN, K.L. YANG, and M.J. MADOR (With 3 Figures) . . 201 Sleep and Asthma
M.F. FITZPATRICK, C.M. SHAPIRO, and N.J. DOUGLAS
(With 3 Figures) ... 209 Mechanical Ventilation in the Treatment
of Sleep-Related Breathing Disorders
H. BECKER, I. FElT, M. RIESS, H. SCHNEIDER, A. STAMNITZ, K. WEBER, J.H. PETER, and P. VON WICHERT (With 5 Figures) 220 The Efficiency of the MESAM System
in Long-Term Control of nCPAP Therapy
H. BECKER, G. AMEND, W. CASSEL, I. FElT, K. MEINZER, T. PENZEL, J.H. PETER, and P. VON WICHERT
(With 5 Figures) ... 229
x
Cyclical Variation of Heart Rate in Sleep Apnea Before and Under Nasal Continuous Positive Airway Pressure Therapy
Contents
I. FEn, G. AMEND, T. PENZEL, S. STEPHAN, R. KLINGENBERG, and J.H. PETER (With 5 Figures) . . . 237 Prevalence of Oxygen Desaturations
and Associated Breathing Disorders During Sleep in Patients
with Chronic Obstructive Pulmonary Disease P.J.E. Vos, H.T.M. FOLGERING,
and C.L.A. VAN HERWAARDEN (With 1 Figure). . . ... 246 Maxillomandibular Advancement for Treatment
of Obstructive Sleep Apnea
P.D. WAITE, J. LACHNER, and V. WOOTEN (With 2 Figures) 251 Results of ENT Examination in Patients
with Obstructive Sleep Apnea Syndrome
and Continuous Positive Airway Pressure Therapy J. MAYER-BRIX, U. MULLER-MARSCHHAVSEN, H. BECKER,
and J.H. PETER (With 2 Figures) . . . 257 Part 5 Sleep and Health Risk in Occupational Medicine
Shift Work and Sleep Disturbances
T. AKERSTEDT (With 1 Figure) ... 265 Sleep Apnea and Accidents: Health Risk for Healthy People?
W. CASSEL and T. PLOCH (With 3 Figures). . . 279 Association Between Sleep Disturbances
and Blood Pressure in Shiftworkers
P. LAVIE (With 1 Figure) ... 286
Part 6 Sleep and Health Risk in Cardiovascular Diseases Blood Pressure in Sleep-Related Disordered Breathing:
A Hypothesis
M.R. LITTNER and D.J. MCGINTY ... ,. .. . . 295 Changes in General Circulation in Sleep Apnea Syndrome
G. COCCAGNA, F. CIRIGNOTTA, and E. LVGARESI
(With 4 Figures) ... 300
Contents XI
Sleep-Related Breathing Disorders and Arterial Hypertension
J. MAYER, U. WEICHLER, B. HERRES-MAYER, R. MOSER,
H. SCHNEIDER, and J.H. PETER (With 5 Figures) . . . 310 Investigations of Arterial Baro- and Chemoreftexes
in Patients with Arterial Hypertension and Obstructive Sleep Apnea Syndrome
M. TAFIL-KLAWE, F. RASCHKE, H. BECKER, H. HEIN, R. STOOHS, A. KUBLIK, J.H. PETER, T. PENZEL, T. PODSZUS, and P. VON WICHERT (With 9 Figures). . . 319
Analysis of Central Apnea in Patients with and Without Left Ventricular Failure
T.D. BRADLEY, Y. TAKASAKI, P. LUI, and R. RUTHERFORD
(With 3 Figures) ... 335 Increased Sympathetic Activity as Possible Etiology
of Hypertension and Left Ventricular Hypertrophy in Patients with Obstructive Sleep Apnea
H. EJNELL, J. HEDNER, K. CAIDAHL, J. SELLGREN,
and G. WALLIN (With 1 Figure) ... 341 Changes in Left Ventricular Ejection Fraction
During Arterial REM Sleep Desaturation
and Exercise in Chronic Obstructive Pulmonary Disease and Sleep Apnea Syndrome
C.M. PISON, 1.M. GAIO, D. FAGRET, P. ROMAND, P.A. LEVY, C. BONNET, J.E. WOLF, C. BRAMBILLA,
and C. GUILLEMINAULT. . . . 348 Pulmonary Hemodynamics
in the Obstructive Sleep Apnea Syndrome
J. KRIEGER and E. WEITZENBLUM (With 1 Figure) . . . 356 Pulmonary Artery Pressure During Central Sleep Apnea
T. PODSZUS, J.H. PETER, C. GUILLEMINAULT,
and P. VON WICHERT (With 2 Figures) . . . 364 Prevalence of Sleep Apnea in Patients
Without Evidence of Cardiac Disease
M. RIESS, J. HOCKMANN, R. FUNCK, U. KOEHLER, W. CASSEL, and J .H. PETER ... 371
XII
Nocturnal Myocardial Ischemia and Cardiac Arrhythmias in Patients with Coronary Heart Disease
and Sleep-Related Breathing Disorders
U. KOEHLER, H. DROSTE, B. HAMANN, T. POMYKAJ,
Contents
and K. WEBER (With 3 Figures). . . 378 Blood Pressure Behavior in Patients
with Sleep Apnea Under Cilazapril Versus Metoprolol U. WEICHLER, B. HERRES-MAYER, R. HOFFMANN, U. MARX, J. MAYER, R. MOSER, T. PENZEL, J.H. PETER, H. SCHNEIDER, K. WEBER, and P. VON WICHERT (With 4 Figures) . . . 386
Part 7 Sleep and Health Risk in Infancy Respiratory Adaptation During Sleep in Infants and Children: Risk Factors
C. GAULTIER (With 3 Figures) . . . 399 Infant Obstructive Sleep Apnea,
Near-Miss Sudden Infant Death Syndrome,
and the Development of Obstructive Sleep Apnea Syndrome C. GUILLEMINAULT and R. STOOHS (With 6 Figures). . . 408 Respiratory Mechanisms During Sleep
That Might Be Responsible
for Sudden Infant Death Syndrome
R. HAIDMAYER, C. EINSPIELER, W. L6sCHER, F. REITERER,
and T. KENNER (With 8 Figures) . . . 425 Respiratory Control Development and Sleep States
in Newborns and During the First Weeks of Life in Humans L. CURZI-DASCALOVA (With 4 Figures). . . 438 Sudden Infant Death Syndrome: Risk Reduction
A. KAHN, E. REBUFFAT, M. SOTTIAUX, and M.F. MULLER.... 448 Children Intolerant to Cow's Milk
May Suffer from Severe Insomnia
A. KAHN, M.J. MOZIN, E. REBUFFAT, M. SOTTIAUX,
G. CASIMIR, J. DUCHATEAU, and M.F. MULLER ... '" 458 Indications of Sleep-Related
Upper Airway Obstruction in Children
E. SVANBORG, H. LARSSON, and B. CARLSSON-NoRD LANDER
(With 3 Figures) ... 468
Contents XIII
Development, Disturbances, and Training of Respiratory Regulation in Infants
M.E. SCHLAEFKE, T. SCHAEFER, B. NEBEL, D. SCHAEFER,
and C. SCHAEFER (With 2 Figures) ... 476 Daytime Hypoxia, Sleep Disturbance,
Nocturnal Hypoxaemia and Retarded Growth in Young Children Who Snore
(Before and After Adenotonsillectomy) Compared with Control Children
l.R. STRADLING, G. THOMAS, and A. FREELAND
(With 2 Figures) ... 486
Pathophysiological Study of the Respiratory Disturbance Caused by Adenoid-Tonsillar Hypertrophy
S. MIYAZAKI, K. TOGAWA, K. YAMAKAWA, Y. ITASAKA,
and M. OKAWA (With 3 Figures) ... . . .. . . .. . 491
Unreliability of Apnea Monitoring in Infants with Sleep-Dependent Hypoventilation
D. SCHAEFER, T. SCHAEFER, and M.E. SCHLAEFKE
(With 2 Figures) ... 497
Part 8 Sleep and Health Risk: Endocrinology Interactions Between
the Hypothalamus-Pituitary-Adrenal System and Sleep in Humans
l. BORN and H.L. FEHM (With 3 Figures). . . 503 Circardian Rhythms of Biogenic Amines
in Health, Stress, and Depression
W. WESEMANN, H.-W. CLEMENT, N. WEINER, F. Xu, M. ROTSCH, E. SCHULZ, and B. FRUHSTORFER
(With 4 Figures) ... 512
Changes in Volume- and Pressure-Regulating Hormone Systems During Nasal CPAP Therapy in Patients with Obstructive Sleep Apnea Syndrome K. EHLENZ, l.H. PETER, K. DUGI, K. FIRLE, R. GOUBEAUD, K. WEBER, H. SCHNEIDER, H. KAFFARNIK,
and P. VON WICHERT (With 6 Figures). . . 518
XIV
Nighttime and Daytime Water and Sodium Excretion in Patients with the Obstructive Sleep Apnea Syndrome:
Effects of Nasal Continuous Positive Airway Pressure 1. KruEGER, M. BARTHELMEBS, E. SFORZA,
Contents
1.-L. IMBS, L. LEHR, and D. KURTZ (With 3 Figures) . . . 532
Part 9 Sleep and Health Risk: Insomnia Health Risk of Insomnia
D.F. KRIPKE, S. ANCOLI-IsRAEL, R.L. FELL, W.l. MASON,
M.R. KLAUBER, and O. KAPLAN. . . . 547 Sleep Quality and Health:
Description of the Sleep Quality Index
H. URPONEN, M. PARTINEN, 1. VUORI, andl. HASAN 555 From Sleep Disorders to Hypnotic Use:
What Happens in the French Population
M.A. QUERA-SALVA, F. GOLDENBERG, M.A. SIMON, A. ORLUC, C. MIRABAUD, 1.T. TCHERNIA, 1. DE LATTRE,
P. PICHOT, and C. GUILLEMINAULT (With 1 Figure) ... 559 Prognostic Significance of EEG Sleep Changes
in Late-Life Depression
C.F. REYNOLDS III,
c.c.
HocH, 0.1. BUYSSE, P.R. HOUCK, S.R. BERMAN, and 0.1. KUPFER (With 2 Figures) . . . .. . 566List of Contributors
The addresses are given at the beginning of each contribution
Akerstedt, T. 265 Amend, G. 229,237 Ancoli-Israel, S. 547 Balzer, H.-U. 58 Barthelmebs, M. 532
Becker, H. 220,229,257,319 Benediktsd6ttir, B. 92 Berman, S.R. 566 Bjornsson, J.K. 92 Bonnet, C. 348 Born, J. 503 Bradley, T.D. 335 Brambilla, C. 348 Buysse,D.J. 566 Caidahl, K. 341
Carlsson-Nordlander, B. 468 Casimir, G. 458
Cassel, W. 167,229,279,371 Cirignotta, F. 84, 154,300 Clement, H.-W. 512 Coccagna, G. 84, 154, 300 Curzi-Dascalova, L. 438 0' Alessandro, R. 84 de Lattre, J. 559 Dement, W.e. 146 Douglas, N.J. 174,209 Droste, H. 378
Duchateau, J. 458 Dugi, K. 518 Ehlenz, K. 518 Ehlers, A. 161 Einspieler, e. 425 Ejnell, H. 341 Fagret, D. 348 Faust, M. 101
Fehm, H.L. 503 Fell, R.L. 547
Fett, I. 167,220,229,237 Fietze, I. 58
Firle, K. 518
Fitzpatrick, M.F. 174,209 Fletcher, E.e. 183 Folgering, H.T.M. 246 Fossey, E. 174
Freeland, A. 486 Fruhstorfer, B. 146,512 Funck, R. 371
Gaio, J.M. 348 Gaultier, C. 399 Gerardi, R. 154 Gislason, T. 92 Gobel, M. 161 Goldenberg, F. 559 Goubeaud, R. 518 Grote, L. 37
Gudmundsson, J. 92 Guilleminault, e. 108, 146,
348,364,408,559 Haidmayer, R. 425 Hamann, B. 378 Hasan, J. 555 Hedner, J. 341 Hein, H. 319 Henn-Kolter, C. 167 Herres-Mayer, B. 310,386 Hoch, e.e. 566
Hockmann, J. 371 Hoffmann, R. 386 Houck, P.R. 566 Imbs, J.-L. 532
XVI
Itasaka, Y. 491 Kaffarnik, H. 518 Kahn, A. 448,458 Kamphuisen, H.A.C. 50 Kaplan, O. 547
Kayed, K. 3 Kemp,B. 50 Kenner, T. 425 Kiss, E. 137 Klauber, M.R. 547 Klingenberg, R. 237 Koehler, U. 371, 378 Krieger, J. 356, 532 Kripke, D.F. 547 Kristbjarnarson, H. 92 Kublik, A. 319
Kupfer, D.J. 566 Kurtz, D. 532 Lachner, J. 251 Larsson, H. 468 Lavie, P. 286 Lehr, L. 532 Levy, P.A. 348 Littner, M.R. 295 LOscher, W. 425 Lugaresi, E. 84,300 Lui, P. 335
Mador, M.J. 201 Margraf,J. 161 Marx, U. 386 Mason, W.J. 547 Mayer,J. 310,386 Mayer-Brix, J. 257 McGinty, D.J. 295 Meinzer, K. 229 Mignot, E. 146 Miles, L.E. 28 Mirabaud, C. 559 Mitler, M.M. 65 Miyazaki, S. 491 Mondini, S. 154 Moser, R. 310, 386 Mozin, M.J. 458 Muller, M.F. 448,458
Miiller-Marschhausen, U. 257
List of Contributors
Nebel, B. 476 Nishino, S. 146 Okawa, M. 491 Orluc, A. 559
Parmeggiani, P.L. 119 Partinen, M. 84, 108, 555 Pasterkamp, H. 193 Penzel, T. 11,37,229,237,
319,386
Peter, J.H. 11,37,101,167, 220,229,237,257,310,319, 364,371,386,518
Pichot, P. 559 Pison, C.M. 348 Ploch, T. 101,279 Podszus, T. 319,364 Pomykaj, T. 378 Quera-Salva, M.A. 559 Raschke, F. 319 Rebuffat, E. 448, 458 Reiterer, F. 425 Reynolds III, C.F. 566 Riess, M. 220, 371 Romand, P. 348 Roth, W.T. 161 Rotsch, M. 512 Rutherford, R. 335 Schaefer, C. 476 Schaefer, D. 476,497 Schaefer, T. 476,497 Schiavina, M. 154 Schlaefke,M.E. 476,497 Schmidt-Nowara, W.W. 78 Schneider, H. 37,220,310,
386,518 Schultze, B. 101 Schulz, E. 512 Schulz, H. 137
Schwarzenberger-Kesper, F.
167
Sellgren, J. 341 Sforza, E. 532
Shapiro, C.M. 124,174, 209
Simon, M.A. 559
List of Contributors
Smith,l.R. 20 Sottiaux, M. 448, 458 Stamnitz, A. 220 Stephan, S. 167, 237 Stoohs, R. 319,408 Stott, F.D. 37 Stradling,l.R. 486 Svanborg, E. 468 Tafil-Klawe, M. 319 Takasaki, Y. 335 Taylor, C.B. 161 Tchernia,l.T. 559 Thomas, G. 486 Thorleifsdottir, B. 92 Tobin, M.l. 201 Togawa, K. 491 Urponen, H. 555
van Herwaarden, C.L.A. 246
XVII
von Wichert, P. 37,220,229, 319,364,386,518
Vos, P.l.E. 246 Vuori, I. 555 Waite, P.O. 251 Walch,l.K. 78 Wallin, G. 341
Weber,K. 220,378,386,518 Weichler, U. 310,386 Weiner, N. 512 Weitzenblum, E. 356 Wesemann, W. 512 Wiggins, c.L. 78 Wolf,l.E. 348 Wooten, V. 251 Xii, F. 512
Yamakawa, K. 491 Yang, K.L. 201
Part 1 Sleep and Health Risk: Methodology
The Present State of Ambulatory Monitoring of Sleep
K. KAYED1
Introduction
The pace of new developments in any field of clinical investigation is largely determined by the evolution of technology. The extremely rapid innovations in the field of electronics and computers resulted in the production of several ambulatory devices that are used routinely as diagnostic tools by medical specialties. In the field of sleep, standard polysomnography (PSG), the most important investigative procedure, is carried out in a laboratory environment under strict standardized guidelines. Standard PSG has always been known to be a complex procedure, time consuming, and relatively expensive, some- times providing large amounts of unnecessary data. The impact of rapid evolution of medical technology on sleep investigation has resulted in the introduction of several ambulatory devices for the recording of sleep and its associated physiological parameters that have demonstrable advantages over more complicated forms of evaluation although need not be a replacement for them.
The rationale of ambulatory monitoring is to make prolonged recording of sleep and its associated phenomena more practical and economic than could be possible by standard PSG. Ambulatory recording has the advantage of allowing the investigation to take place within a more natural environment, in the subject's customary life-style, giving a truer picture of the subject's pathological condition.
Long-term ambulatory monitoring originated in the field of cardiology, where ECG recording by Holter systems using single-channel tape recorders provided the cardiologists with informative diagnostic data. Subsequently, multi-channel tape recorders were introduced to record sufficient EEG information so that longterm ambulatory recording became an established procedure in neurology, mainly in the evaluation of seizure disorders. The application of ambulatory monitoring in sleep is still in its early phases of development. Only recently, several methods have been introduced to record sleep and its associated phenomena by various ambulatory methods that
1 Department of Clinical Neurophysiology, Akerhus Central Hospital, 1474 Nordbyhagen, Norway.
4 K. Kayed include analog tapes, solid-state monitors, telephone transmission systems, strip-chart recorders, and local telemetric devices.
The term "ambulatory" in the medical literature means "not in bed"
"walking" when describing the state of a patient. For a device, it can mean either portable or movable from one place to another, denoting that these devices have to be small and lightweight. Therefore ambulatory devices can include those which are carried or attached to the patient as well as devices that are placed by his/her bedside. With this definition in mind, the number of devices that can be included in this category will be substantial.
Before listing various types of ambulatory monitoring devices that can be used in the field of sleep, it may be pertinent to list what are the different physiological sleep parameters that they can record.
The following are the main sleep parameters that can be recorded by ambulatory methods:
Sleep stages according to standard criteria (EEG - EOG - EMG) Sleep states (awake - NREM - REM)
Respiration (RIP - strain gauges - thermistors - impedance - magneto- meters)
Cardiovascular (ECG - blood pressure) Movements (eye - limb - head - total) Body position
Oxygen saturation Gastric pH
Nocturnal penile tumescence (NPT) Respiratory sounds
Temperature Light
Galvanic skin resistance (GSR)
All the above-mentioned parameters can be recorded either individually or in various combinations using ambulatory systems. The following is an effort to list systematically these systems. One representative example is given for each:
Solid-state sleep computers for EEG (e.g., Brain-Quick) Solid-state sleep computers (e.g., SAC Microtronics) Analog EEG tape recorders (e.g., Oxford Medilog 9000) Telemetric systems (e.g.,Nightwatch AMT)
Telephone transmission systems (e.g., Telediagnostics) MuItiparameter solid-state systems in various combinations:
Resp/eye/body/ECG/02sat/position (Vitalog Lunchbox) Resp/eye/body /delta/EMG (Somnolog)
Resp/02sat/ECG (Biochem 77 pulse oximeter) Movement/02sat (SCSB systems)
The Present State of Ambulatory Monitoring of Sleep
ECGlrespiratory sounds (Mesam) Eye/body movement (Nightcap) Eye/body /EM G (Actioculograph) Body movement/light (Actilume AMI) Respiration/ECG (SIDS monitors) 02sat/pulse (Oximeters)
Single-parameter solid-state monitors:
5
(ECG - respiration - 02sat - pH - NPT - BP - temperature - activity) Strip-chart monitors
Behavioral monitors (biofeedback systems) Alarm systems (e.g., SIDS monitors)
Solid-State EEG and Sleep Computers
Solid-state EEG machines and sleep computers are basically an IBM-AT or compatible computer modified to receive EEG or sleep data and provide paperless systems to store, display, and score sleep either visually or by on-line automatic analysis. Raw data can be preserved on a relatively inexpensive storage medium. The continuous reduction in the price of storage media and their ability to process large amounts of data will make these systems very attractive alternatives to standard PSG. In addition, the improvements in the methods of data transmission will allow efficient transfer of recorded sleep data from the home environment or from outlying hospitals to some central sleep laboratories where data collection and analysis can take place. Expert systems using artificial intelligence and knowledge bases will be another important feature of these systems.
Analog Tapes
There are few commercially available analog tape recorders for multichannel recordings of biodata. The most commonly used in the field of sleep and neurology are the Oxford Medilog system. The use of the portable four-channel Oxford Medilog system for sleep monitoring was introduced by Wilkenson and Mullany in 1976 [1]. The main disadvantage of this system was the limited number of channels available to record biodata.
The development of the Oxford 9000 system increased the number of the channels to eight while dedicating the ninth channel to time and event recording. For several years, this system has been used in our laboratory to carry out 24-h recording of ambulatory PSG and the multiple sleep latency test (MSLT) for the diagnosis of hypersomnia. The application of the system to record the MSLT at home required a standard cutoff limit of 20 min for the
6 K. Kayed
five sleep periods. The advantages of ambulatory recording of the MSLT are the continuous recording allowing detection of all episodes of sleep, drowsiness, and microsleep periods occurring throughout the day and the possibility of automatic analysis of the tape-recorded sleep data using the Oxford sleep stager.
Ambulatory recording of periodic movements in sleep (PMS) can be carried out by simultaneous recording of PSG and anterior tibial EMG (PMS). PMS can be identified either visually or acoustically by their characteristic sound on the replay system loudspeaker. Recently, we have carried out automatic analysis of ambulatory recorded PMS using the Oxford system in combination with an IBM At compatible personal computer.
Signals from the playback unit were fed to the computer through a 12-bit analog-digital converter where leg jerks were detected, automatically analyzed, and plotted [2].
Figure 1 shows a single-page plot showing the sleep hypnogram and the number of left and right leg jerks as detected automatically by the system. It also shows the number of K-complexes, REMs, alpha and delta activity, artifacts, and submental EMG amplitude.
The recent introduction of the multi parameter analysis system (MPA) allows the recording of a selection of various physiological parameters using the Oxford playback system in combination with the sleep stager. The MPA recorder has four fixed channels to record EEG, EOG, and EMG according to the standard criteria while the other four channels can simultaneously record other physiological parameters including respiration by strain gauges, inductive plethysmography and/or thermistors, ECG, oximetry, NPT, tem- perature, and anterior tibial EMG. Up to 40 different combinations can be selected using parameter combination switches. Data from the MP A are transferred from the replay and display unit to the SSMRKIII Oxford sleep stager for automatic analysis and production of written results and sleep hypnogram.
Telemetric and Telephone Transmission Systems
Ambulatory sleep recording using either local or distant telemetric systems has also been used to record sleep. The telediagnostic system is a portable eight-channel telephone transmission system consisting of an FM multiplexer and demodulation units [3]. Some of the disadvantages of these systems are the introduction of artifacts during telephone transmission and that they still require the continuous attention of a technician while data are recorded on a polygraph or an analog tape recorder. The Nightwatch system (AMI) is a miniature home sleep recording and analysis system using digital radiotelemetry. Optic fiber and satellite communications systems will be the future media for the transmission of sleep biodata.
The Present State of Ambulatory Monitoring of Sleep
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Fig. 1. Single-page plot of automatically detected PMS showing sleep hypnogram, numbers of right and left leg movements, number of K-complexes, REMs, alpha and delta activity, artifacts, and EMG amplitude. Results of automatic analysis are displayed under the plot including total number of events (leg jerks), number of episodes (>30), and number of bursts «30)
8 K. Kayed
Movement Sensors
The recording of total body movements can be carried out by using movement artifact cables placed under the mattress [4], or by using the static charge-sensitive bed (SCSB) [5]. Another approach to body movement recording is use to movement sensors like the wrist actigraph [6]. There are two available types of actigagraph systems using miniature sensors and solid-state storage (AMI and the Zurich systems). Both are computer programmable and require an IBM-type PC computer as data manager.
The actioculograph, which records eye and body movements in addition to the submental EMG, is a further development of the actigraphic principle to record sleep states [7]. The use of miniature sensors to record eye movements during sleep has the advantage of recording pure eye movements not contaminated with delta activity as with standard PSG recording. This is an advantage when automatic analysis of the eye movements is to be considered. Simple systems based on movement recording and analysis like the "nightcap" [8] are very attractive candidates for large-scale epidemiolog- ical sleep studies. The Actilume (AMI) is a new commercially introduced actigraph system that records both activity and the amount of light to which the subject is exposed. This system is used in longterm recording of patients with seasonal affective disorders (SADs) to study the effects of light treatment on these conditions.
Single and Multiparameter Solid-State Monitors
There are at present a large number of systems that can record single or multiple sleep parameters and this number is rapidly increasing. The developments in sensors, solid-state memory storage, and the diagnostic detection and scoring algorithms make these systems interesting to a wider variety of medical specialities. The most important of these group are the solid-state apnea monitors like the Vitalog system, which is the first of this type of monitors to appear on the market.
While these systems are not yet fully accepted by all clinical polysomno- graphers, they are gaining popularity in some specialities, which are interested in focusing on the pathological events during sleep rather than on the sleep per se. Some of these dedicated systems are still in their early phases of development and have not yet been fully validated. Ultimately some of these systems will go through a process of maturation and validation that will make them reliable means for sleep recording either alone or as sup- plementary to standard polysomnography.
The Present State of Ambulatory Monitoring of Sleep 9
Cardiovascular Monitoring During Sleep
Holter monitoring started over a quarter of a century ago and is now an established method for the detection of heart disease. The original 30-kg Holter backpack transmitter is now replaced by several newer devices that weigh les than 500 g and have the power of a few years old mainframe computer. The improvements in the tape recording techniques introduced a new indication for ambulatory monitoring, the detection of silent ischemia, which requires faithful reproduction of the signals to detect changes in the S-T segment.
Noninvasive monitoring of arterial blood pressure during sleep could provide useful information in the evaluation of cardiovascular hemodynamics in basic and clinical medicine. Several ambulatory systems based on conventional sphygmomanometric techniques using cuff-based auscultation and oscillometry are not usually suitable for sleep purposes as the inflation and deflation of the cuff will disturb sleep. New types of noninvasive methods utilizing other techniques that do not interrupt sleep, e.g, photo electrical plethysmography based on the detection of changes in the arterial volume in the human finger, will be more suitable for night recordings.
Requirements for Ambulatory Systems
A major handicap in the development of ambulatory monitoring is the lack of guidelines and standards on their clinical applications and technical specifica- tions. The following are some of the essential requirements that should be taken into consideration for any ambulatory monitoring device:
1. It should provide accurate and reliable diagnostic data.
2. It should be validated for the parameter(s) it records and analyses.
3. It should have some clear advantages over more recording methods concerning cost, patient comfort, and largescale applications.
4. There should be some available guidelines on how, when, and by whom it should be used.
5. It should be safe to use in the home environment.
6. It should be easy to be applied and operated by the patient.
Concluding Remarks
While established clinical polysomnographers consider sleep disorder centers as the proper place for the diagnosis and treatment of all sleep disorders, some newcomers from various specialities would like to have their own
10 K. Kayed: The Present State of Ambulatory Monitoring of Sleep dedicated systems that focus on the pathological events rather than on the various sleep parameters. Sleep studies according to the Association of Sleep Disorder Centers (ASDC) require certified institutions where the commit- ment .has been made to do it properly. Hospitals must be willing to provide the sleep laboratory adequately with monitors, recording machines, space, and a budget. Technologists must be available to work at night and an accredited polysomnographer must be responsible for the overall direction of the laboratory.
Owing to some fundamental differences between the American and European medical systems, few specialized European centers fulfil the ASDC criteria. In Europe, most of the sleep studies are carried out in laboratories that carry out daytime neurophysiological routine work that limit their capacity to carry out additional night work. Training and certification of polysomnographic technicians and clinical polysomnographers is virtually nonexistent. Hence, there is a great need for the development of reliable methods for ambulatory recording of sleep. Ambulatory recording should be considered complementary rather than as a competitor to standard PSG. In a rapidly growing field where new methods are continuously introduced, these methods require validation in terms of their relative strengths and weaknesses and recommendations have to be made concerning the indications for which each is best suited.
References
1. Wilkenson RT, Mullaney D (1976) Electroencephalogram recording of sleep at home.
Post Grad Med J 12:344
2. Kayed K, Roberts S, Davies WL (1990) Computer detection and analysis of periodic movements in sleep. Sleep 13(3):253-261
3. Sewitch DE, Kupfer DJ (1985) Polysomnographic telemetry using Telediagnostic and Oxford Medilog 9000 systems. Sleep 10(6):288-293
4. Azumi K, Sirakawa S, Takahashi S (1977) A proposal of new classification for body movement during sleep. Sleep Res 6:49
5. Alihanka J, Vaahtoranta K (1977) A static charge sensitive bed. A new method for recording body movement during sleep. Electroencephalogr C1in Neurophysiol 46:
733-734
6. Kripke K, Mullaney DJ, Messin S, Wybocaney GV (1979) Wrist actigraphic measure- ments of sleep and rhythm. Electroencephalogr C1in Neurophysiol 44:674-676 7. Kayed K, Hesla PE, R0sj0 0 (1979) The actioculograhpic monitor of sleep. Sleep
2(2):253-260
8. Mamelak A, Hobson JA (1989) Nightcap: a home-based sleep monitoring system.
Sleep 12(2):157-166
Problem-Oriented Diagnosis of Sleep Disorders Using Computerized Methods
T. PENZEL and J.H. PETER'
Introduction
It has become increasingly recognized that sleep disorders and among them sleep-related breathing disorders (SRBD) are highly prevalent. As sleep influences many different physiological parameters, advanced methods to analyze the biological signals are required. Advances in technology and methodology during recent years provided clinicians with many new devices and techniques for recording and analyzing data. But all advances are only helpful in clinical routine if they are part of a diagnostic concept. A stepwise method for diagnosis and treatment control in patients with SRBD has been set up using technology developed in Marburg. The different steps are outlined here with reference to their technologies and methodologies.
First Step: Questionnaire and MESAM for Preselection
Any patient referred to the outpatient department complaining of sleep disorders must first complete a five-item questionnaire. Its purpose is to distinguish patients with general sleep/wake disorders from patients with SRBD. In addition to completing this questionnaire, all patients undergo an ambulatory long-term recording of their heart rate and snoring using the digital MESAM device [1, 2]. This device was developed to preselect patients with suspected SRBD on the basis of physiological parameters. The apparatus, which is now commercially available, records heart rate (HR), and presents the results of a breathing sound analysis. Sounds are recorded by means of a laryngeal microphone. In the recording device the sounds are analyzed by means of two analog filters. Total volume of sound on the one hand and the relative proportion of power below 800 Hz on the other hand are evaluated [3]. Normal breathing, regular snoring, and loud snoring can be
I Medizinische Poliklinik, Zeitreihenlabor, Philipps-Universitiit Marburg, Baldingerstr. 1, W-3550 Marburg, FRG.
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Fig. 1. Schematic outline of the relation between the four steps of the diagnostic method.
All results are documented in a general data base. The first two steps consist of ambulatory methods whereas the later two steps require hospitalization
Problem-Oriented Diagnosis of Sleep Disorders 13
distinguished. HR is calculated beat to beat and recorded simultaneously. All three signals are sampled once per second, they are compressed to 1 byte of information, and stored in a solid state memory (64 kByte of RAM) inside the box. The beginning of the recording is programmable. Uninterrupted recordings up to 18 h can be performed, thus permitting the recording of an entire night and day. After the ambulatory recording is completed, data are read out via a serial link and are stored on diskette for further evaluation.
Data are analyzed for the occurrence of sleep apnea. Most frequently periods of sleep apnea are accompanied by periodic snoring and cyclical variation in HR (CVHR). The term CVHR describes the relative bradycardia during the apnea itself followed by a relative tachycardia accompanying the compensa- tory hyperventilation [4]. Automatic analysis based on the variation of HR which is set in relation to actual mean heart rate is performed using a period analysis. Two independent respiratory disturbance indices (RDI) are calcu- lated. One is the result of HR evaluation, and the other is the result of snoring interval analysis. In addition to automatic analysis, visual scoring for periods of apnea is performed on printouts of raw data. A rough classification in terms of the severity of SRBD is possible after a short period of training. In some cases a parallel recording of oxygen saturation can facilitate the evah;lation in terms of apnea and hypoventilation.
Findings which could not be confirmed are referred to the next step of diagnosis. Patients whose findings are positive SRBD are sent directly to the sleep laboratory for polysomnographic recordings and in order for therapy to be started. The first step of such a method should be kept simple with just one or two parameters. The choice of HR and snoring in our case proved to be very practicable, but other methods can give equally good results. Alternative devices may record activity [5], long-term electrocardiogram (ECG) [4], or oxygen saturation combined with one other respiratory signal.
Second Step:
Ambulatory Diagnosis Using Multiple Channel Recording
In 1981, a four-channel analog recording device was developed in Marburg to diagnose sleep apnea. Transcutaneous oxygen tension, ECG, and thoracic and abdominal respiratory activity measured using inductive plethysmogra- phy are recorded with an Oxford Medilog 4-24 tape recorder [6]. Six of these units are still in use and have proved to be very reliable in comparison to the sleep laboratory. This concept of ambulatory multichannel recording includ- ing the recording of respiratory parameters has become more common today (see Kayed, this volume). As an option the four-channel system can also be used for ambulatory blood pressure recording. In this case, signals are analyzed off-line with a powerful signal processing computer (Intertechnique 1200). Tapes are played back 95 times faster than the recording speed. Blood
14 T. Penzel and J . H. Peter
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0' 12Fig. 2. A printout of raw data enables a trained scorer to count periods of apnea. Apnea phases are often accompanied by intermittent snoring and CVHR. Parallel recording of oxygen saturation (Sa02) facilitates the interpretation of periods of apnea if marked desaturations are found. Each line represents 2 h of recording of snoring (top), heart rate (middle), and Sa02 (bottom). The figure presents an example of a patient with obstructive sleep apnea
Problem-Oriented Diagnosis of Sleep Disorders 15 pressure and parallel ECG are digitized at the equivalent of 60 Hz. The ECG signal is used to detect QRS complexes and to determine instantaneous HR.
On each heart beat detected, first diastolic and then systolic arterial blood pressure values are measured in the raw signal. Mean blood pressure is calculated using all values within 2 s, i.e., 120 values. Using a sample and hold routine systolic, diastolic, mean blood pressure and an instantaneous HR are preserved. Each second, the actual four calculated values are stored on diskette for further statistical analysis (see Weichler et aI., this volume).
The second step may not only serve as a preselection, but also yields a valuable diagnosis in patients with classical obstructive sleep apnea. Other dedicated systems may do an equivalent job in the diagnosis of epilepsy or general sleep/wake disorders. The first two steps described are ambulatory.
Patients with complex respiratory regulation disorders have to undergo further tests in the hospital. Prior to physical or surgical treatment, all patients must undergo sleep laboratory examinations.
Third Step:
Differential Diagnosis of Sleep-Related Breathing Disorders Differential diagnosis of SRBD must be performed by recording multiple channels of respiration. At least one signal must reflect respiratory flow or volume, and a second signal has to reflect respiratory effort or obstruction.
Together with F.D. Stott, Oxford, UK, we developed a mobile device which is designed to distinguish between the different forms of SRBD [7]. These include many forms of SRBD besides central and obstructive sleep apnea:
paradoxical breathing, excessive snoring, and prolonged periods of hypoventilation accompanied by oxygen desaturation were detected. Myoclo- nus, which might be masked by apnea, can be distinguished from efforts accompanying arousal responses. (see Schneider et aI., this volume).
The new ten-channel device records thoracic and abdominal respiratory efforts by means of inductive plethysmography, as well as oxygen saturation (SaOz) and HR by pulse oximetry. Electrooculogram (EOG) and activity, by means of a movement sensor based on an optical principle, are recorded to differentiate between states of wakefulness, slow-wave sleep, and rapid eye movement (REM) sleep. Nasal airflow and a noninvasive intrathoracic pressure sensor (ITP) are used to distinguish the different forms of disturbed respiration. Two further channels are provided and can be used by different options. These may be ECG, blood pressure, electroencephalogram (EEG), or electromyogram (EMG).
All parameters are digitized at 100 Hz sampling rate, except HR and SaOz where a sampling rate of 1 Hz is sufficient. Data are sent to a personal computer in blocked format once per second. Data are stored on hard disk, printed on a color ink jet printer, and displayed on a color graphic display
16 T. Penzel and J. H. Peter
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simultaneously during recording. Respiratory frequency and volume are calculated continuously. Statistical evaluation allows data to be compressed to yield an overview of an entire night's recording. Different histograms support the decision for a specific diagnosis. Data are analyzed interactively to ensure proper classification of apnea.
Apart from its diagnostic value, the third step is sufficient for adjusting nasal CPAP treatment in patients with obstructive sleep apnea, because it makes it possible to record the necessary respiratory parameters and parallel Sa02, and to determine the state of sleep using EOG and an activity test.
Patients with more problematic sleep disorders and who need standard EEG recording have to undergo polysomnography in the sleep laboratory.
Fourth Step: Sleep Laboratory Recordings
Polysomnographic recordings must be made for diagnostic reasons in patients with general sleep/wake disorders and patients with SRBD combined with other disorders. EEG recording is then essential to differentiate the causes of the disturbed sleep. EEG is recorded in addition to the physiological parameters mentioned above. The Equipment in the sleep laboratory also allows investigations with invasive blood pressure recordings, i.e., pulmonary and systemic blood pressure, to be performed under conditions of permanent
Problem-Oriented Diagnosis of Sleep Disorders 17 supervision [8]. Treatment of patients with severe nocturnal respiratory problems must be adjusted in a sleep laboratory.
New methodologies with on-line EEG analysis support the visual evaluation of sleep recordings. Some approaches do parallel evaluation of respiration and Sa02 with the additional possibility of adjusting alarm levels (see Smith, this volume). Most methods support on-line and off-line analyses to condense the nocturnal recording and thus yield a report of events.
EEG Analysis in Sleep Disorders
A vigilance classification is carried out based on Fourier transforms of short time windows of 2 s width [9]. Each segment of EEG is reduced to four characteristic values. The first value is the mathematical norm of the signal, a value which is related to the power of the EEG. The three other values are characteristic frequencies. Based on a power spectrum of each EEG segment, a power distribution function reaches 30%, 50% and 70% of total power are measured. These frequencies are no longer fixed to arbitrary frequency bands. If the three frequency values are close together, a narrow peak in the original power spectrum at the corresponding frequency is found. Great differences in frequency values reflect more even distribution of power. A classification based on Loomis [10] was developed by statistical analysis of the four-dimensional parameter space. An 81% agreement for a test set of manually classified segments could be reached. To evaluate REM sleep, variance of EOG and EMG are calculated in parallel. The classification preserves a detailed description of physiological and fragmented sleep structure. Short arousals such as those terminating apnea phases can only be found by a classification which uses short time windows as this one does.
Different approaches of automatic sleep analysis may serve different purposes adequately [11] (see Kemp, this volume).
Analysis of Non-EEG Parameters
As outlined earlier, the so-called-non-EEG parameters, i.e., parameters apart from EEG, EOG, and EMG, according to Rechtschaffen and Kales are indispensible in polysomnographic recording. All those parameters men- tioned in step three of the stepwise method should be included, i.e., respiratory signals, blood gases, ECG, and blood pressure. To quantify snoring, laryngeal microphone recordings are useful. The extent of obstruc- tion can be quantified with esophageal pressure sensors. The close rela- tionship between the state of sleep - as reflected by the EEG - and the other cardiorespiratory parameters becomes obvious when the technique of compressed spectral arrays as introduced by Hanson is used [12]. The state termed "awake" is characterized by dominant alpha activity. At this stage,
18 T. Penzel and J. H. Peter
E E G Power Spectra 10 min
T
RC Abd 8P Sa 0, C Abd BP Sao,
Fig. 4. A compressed spectral array with parallel oxygen saturation (SaO]), blood pressure (BP) and respiration (RC and Abd) shows the influence of sleep on physiological parameters
the regulation of respiration is not disturbed. As soon as a patient with SRBD falls asleep, alpha activity diminished, and theta and delta activity increase;
respiration becomes instable and the first apnea phases occur.
During sleep more severe apnea phases with marked drops in Sa02 and dramatic changes in arterial blood pressure occur during periods of REM sleep. The analysis of respiratory frequency and volume in parallel with EEG gives indications of interactions which influence the choice of therapy.
Conclusions
The outpatient department of internal medicine in Marburg has to deal with many patients complaining of sleep disorders. Therefore, it was indispensible to introduce a system for preselecting patients and for determining the appropriate method of diagnosis. Analytical methods and new devices are integrated in the comprehensive concept which proved to be useful for clinical routine and for scientific research. The stepwise system allows the application of methods which result in an efficient diagnosis of sleep disorders.
In all steps of the diagnostic concept, methods of signal analysis are involved. The various physiological parameters require different methods of signal analysis. The concept is open to include new methods which improve automatic evaluation of sleep studies. Redundant examinations can be avoided and the efficiency of diagnostic procedures is ensured.
Problem-Oriented Diagnosis of Sleep Disorders 19
References
1. Peter JH, Fuchs E, Hugens M, Kohler U, Meinzer K, Muller U, von Wichert P, Zahorka M (1987) An apnea-monitoring device based on variation of heart rate and snoring. In: Peter JH, Podszus T, von Wichert P (eds) Sleep related disorders and internal Diseases. Springer, Berlin Heidelberg New York Tokyo, pp 140-146 2. Penzel T, Amend G, Meinzer K, Peter JH, von Wichert P (1990) MESAM: A heart
rate and snoring recorder for detection of obstructive sleep apnea. Sleep 12: 13(2):
176-182
3. Penzel T, Amend G, Peter JH, Podszus T, von Wichert P, Zahorka M (1988) Objective monitoring oftherapeutical success in heavy snorers: a new technique. In: Chouard CH (ed) Chronic Rhonchopathy. Libbey, London, pp 273-278
4. Guilleminault C, Connoly S, Winkle R, Melvin R (1984) Cyclical variation of the heart rate in sleep apnea syndrome: mechanisms and usefulness of 24h electrocardiography as a screening technique. Lancet I: 126-131
5. Sadeh A, Alster J, Urbach D, Lavie P (1989) Actigraphically based automatic bedtime sleep-wake scoring: validity and clinical applications. JAmb Monit 2
6. Peter JH (1985) Holter monitoring technique in a comprehensive approach: ambula- tory monitoring of sleep apnea. In: Hombach V, Hilger HH (eds) Holter monitoring technique. Schattauer, Stuttgart, pp 127-149
7. Penzel T, Peter JH, Schneider H, Stott FD (1989) The use of a mobile sleep laboratory in diagnosing sleep related breathing disorders. J Med Engin Technol 13: 100-103 8. Podszus T (1990) Hemodynamics in Sleep Apnea. In: Surratt P, RemmersJ (eds) Sleep
a~d Respiration, Wiley-Liss, New York, pp 353-361
9. Penzel T, Petzold J (1989) A new method for the classification of subvigil stages using the fourier transfonn and its application to sleep apnea. Com put Bioi Med 19:7-34 10. Loomis AL, Harvey EN, Hobart III GA (1937) Cerebral stages during sleep, as
studied by human brain potentials. J Exp Psychol 21:127-144
11. Hasan J (1983) Differentiation of normal and disturbed sleep by automatic analysis.
Acta Physiol Scand [Suppl] 526: 1-103
12. Hanson K, Stockard JJ, Kalichman M, Bickford RG (1974) Compressed spectral somnogram-multiparameter spectral sleep display. Proc San Diego Biomed Symp 13:545-548
Computer-Assisted Polysomnograpby*
J.R. SMITH!
Introduction
The computer can serve as an important tool in polysomnography.
Contemporary polysomnography is made possible by recent technological advances; polysomnographic studies can be further facilitated and expanded by the judicious application of computers. Computers can collect, store, and manage data, generate reports, serve as labor-saving devices, provide a means of standardization, and automatically generate quantitative and objective data. The "judicious application" implies that if sufficient thought does not go into how the computer is utilized the application may not help, but can instead lead to erroneous data.
Data Collection
The computer can be used for collecting and storing all of the raw data.
Recent advances in computer technology provide for the economical storage of large data files. An 8-h recording occupies approximately 60 megabytes of data. Just 5 years ago there was not a practical way to store this amount of data. Two relatively inexpensive alternatives today are digital tapes and optical disk cartridges. Optical disk storage has the advantage over tape storage that any epoch of the record can be quickly retrieved (random access). Digital tape storage is still less expensive than storage on optical disk, but the optical disk storage cost per record is now less than U.S.$15, and the cost continues to decrease. If desired, the data can first be stored on the computer's hard disk and subsequently transferred to optical disk for permanent storage. A paper record can be obtained by replaying the digital data through a d/a converter to a polygraph. This procedure can provide the same polygraph recording as if the subject had been recorded on line in the
• This research was partially supported by grants NSF # ICI-8511857 and NS-19996.
1 Electrical Engineering Department, University of Florida, Gainesville, FL 32611, USA.
