During the decade of the 1980s_

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					                        Clinical Perspectives




    CLINICAL UTILITY OF NOCTURNAL OXIMETRY:



                  A Regional
                  Experience
                                                              by Ron Van Drunen, RPSGT




D  uring the decade of the 1980s,
with the field of sleep disorders
diagnosis and treatment in its
                                                                             page) to evaluate the role of
                                                                             oximetry in assessing sleep disor-
                                                                             ders by comparing nocturnal
early stages, the formal nocturnal                                           oximetr y versus nocturnal
polysomnogram (NPSG) was                                                     polysomnography as a method of
established as the “gold standard”                                           diagnosing sleep disorders.
tool for sleep medicine specialists
to use in formulating a clinical                                             Diagnostic Methods
diagnosis. The 1990s were char-                                                Use of overnight oximetry in
acterized by an explosive growth                                             evaluation of sleep disorders falls
in the awareness of sleep disor-                                             into a continuum of methods
ders as common, treatable dis-                                               used to produce a sleep disorders
eases. As sleep medicine became                                              diagnosis. The continuum of
a more generally accepted field of                                           methods, from most sophisti-
treatment and diagnosis, efforts      actigraphs, 1 respiratory moni-        cated to least is:
were made to find simpler and/or      tors, 2 ambulator y systems, 3 , 4
less expensive alternatives to the    questionnaires,5 and oximeters.6       • Full attended nocturnal
NPSG. Articles have been pub-           In preparing this article, I         polysomnogram
lished describing such alternative    interviewed experienced sleep          • Full non-attended nocturnal
methods, which include use of:        specialists (see sidebar on next       polysomnogram




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                                    Clinical Perspectives




        Panel of Experienced Sleep Specialists
        R. Obo Addy, MD, Diplomate of the American Boards of        David Quimby, MD, Diplomate of the American Boards of
        Clinical Neurophysiology, Psychiatry, and Sleep Medicine;   Pulmonary Medicine and Sleep Medicine; Sleep Disorders
        Sleep Disorders Centers, Spectum Health and St. Mary’s      Centers, Gerber Memorial Hospital, Fremont, MI, and Pen-
        Hospital, Grand Rapids, MI                                  nock Hospital, Hastings, MI

        Timothy Daum, MD, Diplomate of the American Boards of       John Schuen, MD, Diplomate of the Pediatric Pulmonary
        Pulmonary Medicine and Sleep Medicine; Sleep Disorders      Medicine Society; Pediatric Sleep Disorders Center, DeVos
        Center, United Memorial Hospital, Greenville, MI            Children’s Hospital, Grand Rapids, MI

        Randall Kehr, MA, RRT, Director of Respiratory Care,        Glenn M. Van Otteren, MD, Diplomate of the American
        Spectrum Health, Grand Rapids, MI                           Boards of Pulmonary Medicine and Sleep Medicine; Sleep
                                                                    Disorders Center, Mecosta County General Hospital, Big
        Lee Marmion, MD, Diplomate of the American Boards of        Rapids, MI
        Sleep Medicine and Neurology; Sleep Disorders Center,
        Holland Community Hospital, Holland, MI




       • Respiratory monitor with               Marmion, there is no value in           $1,500 (as reported by Randall
       compressed electroencephalo-             using an oximeter to test for           Kehr, MA, RRT) while the cur-
       gram                                     these and many other non-res-           rent charge for an overnight
       • Respiratory monitor                    piratory-related sleep disor-           oximetry study ranges from
       • Nocturnal oximetry                     ders. Therefore, in this article,       about $60 to $120 (according
       • Actigraph (measures motion)            the discussion concerns use of          to CareLink Home Medical
       • Subjective data (information           nocturnal oximetry as a diag-           Equipment and Supplies,
       obtained from interviewing the           nostic tool for breathing disor-        Grand Rapids, MI). An
       patient and/or bed-partner).             ders of sleep such as obstructive       overnight oximetry study is
                                                sleep apnea syndrome or noc-            usually more convenient for
          The cost associated with              turnal hypoventilation syn-             both the patient and the tech-
       each type of method would fol-           drome.                                  nician. While an NPSG gener-
       low the same continuum, with                                                     ally requires an overnight visit
       the most expensive test being                                                    to a sleep disorders center, an
       the method at the top of the list.                                               oximetr y normall y just
       It should also be noted that as                                                  requires a visit to a patient’s
       you proceed down the list, the                                                   home in the evening and morn-
       difficulty of interpretation                                                     ing to drop off and pick up the
       increases. In other words, the                                                   device.
       simpler the method of diagno-                                                       Dr. John Schuen uses an
       sis, the greater the skill-level                                                 oximeter for in-home titra-
       demands upon the clinician and                                                   tions of oxygen in children
       physician collecting and inter-                                                  with bronchopulmonary dys-
       preting the data.7                                                               plasia (BPD). Dr. Marmion
                                                                                        says that he has found noctur-
       Formulating a diagnosis                  Advantages of oximetry                  nal oximetry useful in oxygen
          Since there is no oxygen                                                      titrations involving adult
       desaturation associated with               There are two advantages of           patients.
       narcolepsy, insomnia, nocturnal          nocturnal oximetry compared
       seizure disorder, periodic limb          with NPSG: cost and conve-              Disadvantages
       movements of sleep, or REM               nience. The current charge for          of oximetry
       (rapid eye movement) behavior            a full nocturnal polysomno-               “An overnight oximetr y
       disorder according to Dr. Lee            gram is approximately $900 to           study, while less expensive and



76   AARC Tımes     De c e mb e r 1999
                             Clinical Perspectives



more convenient than a nocturnal polysomnogram,
is also far less sensitive as a diagnostic tool,” accord-
ing to Dr. Marmion. “While the oximetry study is
potentially useful in screening some patients for
obstructive sleep apnea syndrome and nocturnal
hypoventilation syndrome, the NPSG is a specific
test for diagnosing not only all breathing disorders of
sleep, but most other sleep disorders as well.”
   Dr. David Quimby says he would have concern
about using a device that can only tentatively iden-
tify one sleep disorder while ignoring others. “I
certainly am not going to recommend a patient
have a surgical procedure such as UPPP (uvu-
lopalatopharyngoplasty) performed based on the
data retrieved from an overnight oximetry,” he
explains. “The patient could have positional
apnea, periodic limb movements of sleep, or the
study could simply reflect artifact. A nocturnal
polysomnogram identifies these other pathologies
and problems.”
   In addition to being a more comprehensive
method for diagnosis, an NPSG provides better
quality information when compared with an oxime-
try study. “At our sleep disorders centers, we have
found the NPSG to be a highly sensitive and specific
tool for diagnosing sleep disorders,” says Dr. R. Obo
Addy. “If a patient has a significant sleep disorder, an
NPSG in our center will effectively identify it. My
impression of nocturnal oximetry as a diagnostic tool
for sleep-disordered breathing is that of a somewhat
hit-and-miss approach.”
   In fact, a recent paper concludes that there is even
potential for significantly different results from an
oximetry study performed on the same patient with
different brands of oximeters.8
   Dr. Glenn Van Otteren says, “I have tried utilizing
oximetry in certain cases where an NPSG was diffi-
cult to arrange; however, the results just did not war-
rant the effort. Usually, the patient needed to be stud-
ied in the sleep lab for confirmation of the diagnosis.”
   Dr. Timothy Daum states, “Since there are
already difficulties associated with making an inter-
pretation based on the data I receive from a four-
channel recording device we occasionally use on
inpatients, I would be even more hesitant to
attempt to diagnose a patient with sleep disorders
by making use of a single-channel oximetry study.”
   Some sleep specialists believe another potential
pitfall of using oximetry to avoid the cost of an
NPSG relates to the situation where oximetry can
sometimes actually add a layer of cost. Dr. Daum



                                                            A ARC Tımes   D e c e m b e r 19 9 9   77
                                      Clinical Perspectives




       references
       1. Chang, A., Kushida, C., Palombini, L., et al. (1999, April    8. Davila, D., Richards, K., Marshall, B., et al. (1999, April
       15). Comparison study of actigraphic, polysomnographic,          15). Oximeter’s acquisition and display modes influence
       and subjective perception of sleep parameters [Supple-           assessment of SpO2 [Supplement 1]. Sleep, 22.
       ment 1]. Sleep, 22.                                              9. Yamashiro, Y., & Kryger, M.H. (1995). Nocturnal oximetry:
       2. Scherr, J., Meyer, M., Berg, R., et al. (1999, April 15).     Is it a screening tool for sleep disorders? Sleep, 18(3),
       Comparison of portable polysomnographic equipment                167-171.
       with standard laboratory polysomnographic evaluation of          10. Levy, P., Pepin, J.L., Deschaux-Blanc, C., et al. (1996,
       normal controls and patients with sleep disorders [Supple-       February). Accuracy of oximetry for detection of respiratory
       ment 1]. Sleep, 22.                                              disturbances in sleep apnea syndrome. Chest, 109(2),
       3. Zomer, J., Hadas, N., & Lavie, P. (1999, April 15). A novel   395-399.
       integrated disposable sleep apnea screening device: A            11. Epstein, L.J., & Dorlac, G.R. (1998, January). Cost-
       preliminary report [Supplement 1]. Sleep, 22.                    effectiveness analysis of nocturnal oximetry as a method
       4. Phillip, P., Taillard, J., Bioulac, B., & de Villemeur, P.    of screening for sleep apnea-hypopnea syndrome. Chest,
       (1998, April 15). DP2000: A new ambulatory procedure for         113(1), 97-103.
       the diagnosis of nocturnal breathing disorders [Supple-          12. Sano, K., Nakano, H., Ohnishi, Y., et al. (1998, Novem-
       ment]. Sleep, 21.                                                ber). Screening of sleep apnea/hypopnea syndrome by
       5. Chung, K-F. (1999, April 15). Using self-reported ques-       home pulse oximetry [In Japanese]. Nihon Kokyuki Gakkai
       tionnaire and anthropomorphic measurements to prioritize         Zasshi, 36(11), 948-952.
       sleep apnea patients for polysomnography: A Hong Kong            13. Ryan, P.J., Hilton, M.F., Boldy, D.A., et al. (1995, Sep-
       experience [Supplement 1]. Sleep, 22.                            tember). Validation of British Thoracic Society guidelines
       6. Schenkel, E. (1998, April 15). Oximetry pattern as a pre-     for the diagnosis of the sleep apnoea/hypopnoea syn-
       dictor of the presence of sleep disorders [Supplement].          drome: Can polysomnography be avoided? Thorax, 50(9),
       Sleep, 21.                                                       972-975.
       7. Pascualy, R., Littner, M., Quan, S.F., et al. (1998, Novem-   14. Chiner, E., Signes-Costa, J., Arriero, J.M., et al. (1999,
       ber 21-22). Indications for the clinical use of unattended       November). Nocturnal oximetry for the diagnosis of the
       portable recording for the diagnosis of sleep-related            sleep apnoea hypopnoea syndrome: A method to reduce
       breathing disorders. American Sleep Disorders Association        the number of polysomnographies? Thorax, 51(11),
       Position Statement [Board meeting].                              968-971.



      agrees that trying to use oxime-               Yamashiro and Kryger con-                 the nocturnal polysomnogram
      try and other screening devices             clude their article on nocturnal             — especially if used in a “split-
      presents a dilemma for him.                 oximetry with a powerful state-              night” format in which the
      “Most results I have obtained               ment: “In the final analysis, one            patient is both diagnosed and
      from using nocturnal oximetry               must decide on the clinical role             started on treatment in the
      or overnight screens have been              of oximetr y and indeed any                  same night — results in the
      inconclusive. After a negative              screening or other test. What                quickest, most accurate, and
      result, I have often questioned if          does one do with a positive test?            least costly diagnosis. b
      the patient was awake all night,            What does one do with a nega-
      or perhaps sleeping in only one             tive study? If the answer to both            Ron Van Drunen is a registered
                                                                                               polysomnographic technologist and
      position. After a positive result, I        questions is the same, then the
                                                                                               manager of the Sleep Disorders Cen-
      often questioned if the patient             test does not truly help in the              ter at Spectrum Health in Grand
      was sleeping supinely all night,”           decision-making. We conclude                 Rapids, MI.
      he explains. “Even if the results           that home oximetry alone is not
      of the test were conclusive, it             useful in the investigation of
      was still necessar y for the                excessive daytime somnolence.”9                 See the “Tools of the
      patient to go to the sleep lab for             The use of nocturnal oxime-
      a CPAP (continuous positive                 try either as a screen to reduce               Trade” column on the
      airway pressure) titration. It              cost, or in lieu of formal noc-                “Table of Contents” in
      seems to me that nocturnal                  turnal polysomnography,
      oximetry and other types of                 remains controversial.10 – 14 To              this issue for additional
      screens usually just add another            all of the physicians inter-                  resources on this topic.
      cost for the patient to bear.”              viewed for this article, however,



78   AARC Tımes       De c e mb e r 1999

				
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