Home Sleep Testing In The Diagnosis

Otolaryngol Clin N Am 40 (2007) 761–784

Home Sleep Testing in the Diagnosis and Treatment of Sleep Disordered Breathing Minal R. Patel, BAa, Terence M. Davidson, MDb,* a

University of California, San Diego, San Diego, CA, USA UCSD School of Medicine, VA San Diego Healthcare System, 9500 Gilman Drive, Evergreen, La Jolla, CA 92093-0617, USA

b

A 29-year-old male patient presents because his wife complains his snoring is keeping her awake at night. As with many patients who snore, he has been forced to leave the conjugal bed. In self-reporting his symptoms on the following scale: 1 ¼ mild, 2 ¼ moderate, and 3 ¼ severe (Fig. 1), the patient rates snoring as a 2, his apneic episodes with a 1, and daytime sleepiness with a 0. The patient denies other symptoms of sleep disordered breathing (SDB) and requests a surgical procedure to correct his snoring. The authors’ evaluation is shown in Fig. 2. His body mass index (BMI) is 28, neck circumference is 16 in, waist circumference is 38 in, Mallampati is II, tonsil grade is 2, nose is 2/2, and uvula is 3. Fiberoptic endoscopy shows a tongue base score of 2, a lingual tonsil of 3, and an epiglottis of 0. A multichannel home sleep test was performed. The results are seen in Fig. 3. The patient was diagnosed with mild SDB; however, absent other symptoms and greater severity, the primary problem was snoring. The patient was recommended for a continuous positive airway pressure (CPAP) trial at his own expense, but he declined. He was then offered two different surgical options. The first was palatal implants; the second was septoplasty, uvulectomy, palatal implants, and coblation of his lingual tonsils. The patient opted to proceed with palatal implants and would only consider the more extensive surgery if this option failed. Surgery was performed in the office. Six weeks later, the patient reported that his snoring was dramatically reduced, and he had been invited back to his bed.

* Corresponding author. E-mail address: [email protected] (T.M. Davidson). 0030-6665/07/$ - see front matter. Published by Elsevier Inc. doi:10.1016/j.otc.2007.04.012

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Fig. 1. The history and physical examination are assessed using scaled, numeric scores.

SDB includes primary snoring, obstructive sleep apnea, and several other diagnoses. A sleep test is an important tool in the evaluation of any patient who has SDB, be it mild, moderate, or severe. Although some believe they can separate snorers from sleep apneics, or mild from

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Fig. 2. History and physical examination of a 29-year-old male self-referred for snoring.

severe SDB by history and physical examination, objective evaluations have not supported this practice [1,2]. Regardless, insurance companies require an objective measure of the severity of SDB before authorizing CPAP, surgery, or other treatments. Sleep testing originated with the electroencephalogram (EEG) and then added respiratory metrics, oximetry, leg movement sensors, chest and abdominal movement, and eye

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Fig. 3. A multichannel home sleep test shows mild sleep apnea with an Apnea Hypopnea Index of 5.6 and minimal oxygen desaturation. A comprehensive report also includes total sleep time and positional information.

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movement. Respiration has been the single most important measure and is the only measure necessary to objectively document disease severity [3]. Respiration is typically measured with a nasal cannula and/or an oral thermistor measuring mouth breathing. The nasal cannulae are most accurate; they measure pressure and calculate nasal flow. Adult criteria define an apneic event as a 90% or greater decrease in respiratory flow for 10 or more seconds [4]. Hypopneas are variably defined; some define a hypopnea as a 50% decrease in airflow for 10 or more seconds, whereas others require a 75% or greater decrease in airflow for 10 or more seconds [5]. Some criteria even require an oxygen desaturation of 2%, 3%, or even 4% before grading it as a hypopnea [6]. The apneas and hypopneas are typically summed and reported as events per hour. Children have a faster respiratory rate; therefore, the duration of an apnea or hypopnea is typically shortened and, depending on the age of the child, can be anywhere from 6 to 8 seconds [7]. Time courses for adolescents have not been particularly looked at or evaluated but are presumably somewhat intermediate. For adults, an Apnea Hypopnea Index (AHI) of five or more events per hour is considered abnormal; however, most insurance companies do not cover treatment unless the AHI is 15 or more or if the AHI is 5 or more with at least two comorbidities. The most common comorbidities are cardiovascular disease, obesity, daytime sleepiness, and hypertension [8–11]. Table 1 [12–25] lists common SDB comorbidities and their prevalence. Premenopausal women may have significant SDB with much lower severity. Christian Guilleminualt from Stanford University’s Sleep Medicine Program describes a syndrome called the upper airway resistance syndrome, in which there is an increased resistance to airflow in the throat with a decrease in airflow measured at the nose, but not severe enough Table 1 Medical conditions associated with sleep disordered breathing (SDB) and the prevalence of their association with SDB Category

Condition

Cardiac

Hypertension Drug-resistant hypertension Congestive heart failure Ischemic heart disease Dysrhythmias Atrial fibrillation Pulmonary hypertension Asthma Stroke Type II Diabetes Metabolic syndrome Morbid Obesity (Male) Morbid Obesity (Female) Gastroesophageal reflux disease Nocturia

Respiratory Neurologic Metabolic

Gastrointestinal Genitourinary

References 30% 83% 76% 38% 58% 49% 77% 18% 90% 15% 50% 90% 50% 60% 48%

[12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26]

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to be measured as a hypopnea [26]. These can result in cortical arousal, disrupt sleep, and cause many or all symptoms of SDB. Women are more prone to upper airway resistance syndrome and significant, symptomatic SDB with lower AHIs. Oximeters are typically used for most home sleep tests. They are not the highly sensitive oximeters physicians use in the operating room and intensive care units. Nonetheless, the data derived are viewed as sacrosanct. An individual who desaturates throughout their sleep study is viewed as having more significant SDB. Some report the lowest oxygen saturation, commonly referred to as the lowest oxygen saturation. The authors are not convinced this is a useful tool. If the oximeter slips on the finger, the oxygen saturation can fall, and the lowest oxygen saturation can inaccurately be reported as low as 60% or 70%. Regardless, looking at the oxygen tracing is useful in assessing SDB. Hypoxemia, a drop in oxygen levels below 90%, is also associated with daytime sleepiness and cerebral dysfunction [27,28]. Chest and abdominal belts are often used to measure obstructive versus central events. The authors do not find this useful for the typical patient consulting a head and neck surgeon. Virtually everyone who snores, which is the premier symptom of SDB, has obstructive sleep apnea. The only people who have significant central SDB are those who have advanced heart failure or a history of stroke. Often, central sleep apnea is described in individuals who have more common SDB. For some individuals, this may be an artifact. Upon sensing the obstructive event, the respiratory effort is stopped. Abdominal and thoracic effort stops. This would then be recorded as a central event when it actually was an obstructive event. Regardless, for an initial sleep test, the obstructive and central events are summed, and whether or not they are viewed as obstructive or central is irrelevant. Home sleep tests are easy to administer. Patients typically come to the physician’s office; a trained technician reviews any questions the patient has about the nature of the test and why they are taking it. The patient is then shown how to apply the various recording devices to their body and how these are connected to the sleep machine. They are then shown how the recording is initiated when going to bed, how it is managed should one arise during the night, and how the recording is stopped upon arising in the morning. The machine is then returned to the physician’s office where the information is downloaded into a computer and the data are analyzed. For most machines, autoscore capability is available, and where autoscore matches the patient’s history and physical examination, it is sufficient. Where the autoscore is borderline and the patient’s history or examination are questionable, manual score capability is important and easily learned. Figs. 4 and 5 demonstrate the steps of administering, downloading, and evaluating a typical patient suspect for SDB. To better describe this process, several cases are presented.

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Fig. 4. The Embletta PDS is a six channel home sleep test that measures nasal respiration, snoring, mouth breathing, respiratory effort, and oxygen saturation.

Case one An 8-year-old boy is referred for surgical evaluation for snoring. Physical examination shows the child has normal height, weight, and BMI; tonsil grade is 3 plus. He is without allergic rhinitis and breathes through his nose at night. The child’s mother had previously sought surgical consultation for him. The physician had recommended that tonsillectomy be performed, but the parents, afraid of the risks and complications, had elected not to proceed. The patient now presents for a second opinion. Before

Fig. 5. In an office setting, a trained technician can show a patient how to put on a multichannel home sleep test.

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rendering an opinion on history and examination alone, a multichannel home sleep test was administered. The child wearing the sleep unit is seen in Fig. 6. While an ongoing study looking at the neuropsychologic consequences of sleep apnea in children was underway, the child enrolled into the research study whereby a neuropsychologic battery was also administered. Given the abnormalities seen in the neuropsychologic evaluation and an abnormal sleep test, namely an AHI of 4.2 events per hour, a recommendation for tonsillectomy was made, and the parents agreed. The procedure was uneventful, and the child made a normal recovery. Three months later, the sleep test and neuropsychologic evaluation were repeated. The results of the home sleep test and the neuropsychologic data before and after surgery are shown in Figs. 7 and 8 and Table 2. In children, an abnormal AHI has not yet been determined. However, current opinion for prepubescent children is that an AHI of 1 or more is in fact abnormal. The authors’

Fig. 6. The Embletta PDS can be worn comfortably by pediatric patients above the age of 4 years.

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Fig. 7. Sleep test of an 8-year-old child referred for snoring. The test shows an Apnea Hypopnea Index of 4.2, a value considered abnormal for a child.

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Fig. 8. The repeat sleep test on the 8-year-old child 6 months later demonstrates that tonsillectomy successfully corrected the SDB.

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Table 2 Pre- and post-neuropsychologic results for an 8-year-old child (raw scores) Test

Domain

Presurgery

Postsurgery

Statue Visual attention Knock–tap Finger tapping PH Finger tapping NPH Sequential tapping PH Sequential tapping NPH

Attention/executive function Attention/executive function Attention/executive function Sensorimotor function Sensorimotor function Sensorimotor function Sensorimotor function

29 34 28 6 9 20 32

27 37 28 9 11 19 36

Abbreviations: NPH, nonpreferred hand; PH, preferred hand.

experience has been that an AHI of 5 or more will most likely not only show improvement in snoring following tonsillectomy, but will also show improvement in behavioral and cognitive functioning. Assuming that 10% of children snore and 1% or 2% have sleep apnea, it seems that there is no documented benefit to operating on the 10%. The only documented benefit is operating on the 2%, a group that presumably has an AHI of 5 or more. The home sleep test seems to be an excellent tool for determining who may or may not benefit from surgical procedures in correcting SDB. The authors’ experience is that current home sleep tests are accurate in children no younger than 4 years of age. Less than age 4, children simply do not have enough respiratory volume to accurately drive the respiratory meters. Case two A 47-year-old male presents with a primary complaint of snoring. He had been snoring for most of his life, but with a recent 10-pound weight gain, the frequency and the loudness of his snoring had increased. His wife complained that, not only did he snore, but he occasionally stopped breathing at night. The patient was a hard-working executive. He had some daytime sleepiness, but believed that this was simply a function of age, work intensity, and lack of regular exercise and normal sleep. On a self-report of his symptoms based on the aforementioned scale in case one (see Fig. 1), he reported his snoring to be a 3, frequency of snoring to be 2, apneic episodes were 2, and daytime sleepiness was 2. History and physical examination are shown in Fig. 9. His neck circumference is 17 in, nose is 2/2, Mallampati is 3, tonsil grade is 0, uvula is 2, and his comorbidities are obesity and hypertension. His endoscopic measurements indicated tongue is 3, lingual tonsils are 1, and epiglottis is 0. The patient underwent a multichannel home sleep test. The results are shown in Fig. 10. The AHI is 16, which is abnormal. In this case, oxygen desaturations are seen, which is associated with deeper stages of sleep. One could argue that this is a milder case of sleep apnea. However, the patient has daytime sleepiness; elevated BMI;

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Fig. 9. History and physical for a 47-year-old male referred for snoring.

elevated AHI; oxygen desaturations; and on physical examination, this is a Friedman Stage III, based primarily on the Mallampati examination. This is sleep apnea. This individual is recommended for CPAP. Nasal surgery and palatal surgery would be unlikely to provide benefit. This individual should not be confused as a snorer but, instead, has sleep apnea, and,

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absent significant weight loss, he will continue to have sleep apnea and needs to be treated effectively with CPAP. Case three A 43-year-old male presents with the identical history as the previous patient. The history and physical examination in Fig. 11 is identical, except that the Mallampati is 4. An overnight home sleep study was performed; results are shown in Fig. 12. In this example, the AHI of 67 events per hour is clearly severe. Fig. 13 demonstrates that the oxygen desaturations are much more evident and much more marked. This is severe SDB. The severity of the condition was explained to the patient. The importance of treatment was also explained, and the patient was recommended for CPAP treatment. The patient was fitted with a nasal mask and an autotitrating positive airway pressure machine. He returned for follow-up 2 weeks later and stated that the autotitrating positive airway pressure machine had changed his life. He was able to sleep 6 or 7 hours per night and feel refreshed in the morning. He stated that it was the most restful sleep he had in years. He began dreaming and, in fact, for the first several nights, his entire sleep was filled with dreams, a phenomenon called rapid eye movement rebound. The patient found himself with more energy during the day, and he no longer fell asleep at work. Before CPAP, his hypertension was poorly controlled on three drugs; now, his blood pressure was rapidly returning toward normal. Of equal benefit, the patient, who did not use alcohol and had suffered from nightly gastroesophageal reflux disease, found that this rather unpleasant malady had disappeared completely. There are several home sleep diagnostic machines available on the market. All of the cases presented in this article were done on the Embletta Portable Diagnostic System (PDS) (Embla, Denver, Colorado). The Embletta is a comprehensive multichannel test that measures respiration by way of a nasal cannula, breathing effort through respiratory belts, oximetry, mouth breathing through an oral thermistor, and snoring through a sensor. Electroencephalogram as an extra component is also available with this particular device. Embla also manufactures a simpler device called the Compass, which can be used as an effective screening tool. The Compass only requires two channels: a nasal cannula and a finger oximeter. A similar device is the ApneaLink (ResMed, Poway, California). This screening tool also has a nasal cannula and oximeter. In cases whereby a nasal cannula may be intrusive to a patient, the Watch-PAT100 (Itamar Medical, Ltd., Caesarea, Israel) can be administered. This device detects apneic events in the finger by interpreting sympathetic nervous system activity by way of a probe. Disposables for the Embletta, Compass, and ApneaLink are less than $5. The Watch-PAT100 probe is slightly more costly, approximately $75 each. The current procedural terminology code for the Embletta and Watch-PAT100 is 95806, whereas the code for the screening devices is

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95806-52. The authors have extensive experience with the aforementioned devices. The home sleep diagnostic industry has grown during the past decade, and various sleep machines are currently available on the market. A list of devices with manufacturer websites is provided in Table 3. The matter of home sleep study validity compared with polysomnogram (PSG) has been greatly debated in recent years. It often seems the arguments are more emotional and economic than they are scientific. Fortunately, the vast majority of insurance companies reimburse for home sleep studies in the greater San Diego area and permit initiation of treatment based on these results. Unfortunately, there are other portions of the country in which this does not occur. It will only occur if head and neck surgeons, other health professionals interested in sleep medicine, and their patients talk with their local consultants and urge them to reconsider the matter. The discussion seems to come to the question of whether home sleep testing is a valid alternative to PSG. Polysomnogram has never been established as a gold standard in the diagnosis of SDB and, in fact, the current practice of split night studies has never been validated against the historical practice of full-night PSG. CMS uses the measure of the AHI or Respiratory Disturbance Index as the criteria for diagnosis and therefore treatment. Home sleep testing and PSG use the exact same equipment to measure respiration. The other PSG measures, most notably sleep stages, which are measured by EEG, are not used for the diagnosis of garden variety obstructive sleep apnea. Therefore, the added channels of the PSG make no contribution to the diagnosis or treatment. Comparing PSG to home sleep studies:

:

 Patients sleep in a lab rather than testing in their own home and bed.  Many PSGs employ split-night studies, so 2 to 4 hours are devoted to diagnosis, and 2 to 4 hours are devoted to setting a CPAP titration pressure; inadequate time periods for both studies; and neither validated against the historical standard of 1 to 2 nights PSG and 1 night CPAP titration.  PSG uses the same respiratory detectors, oximeter, chest and abdomen sensors, and position sensors as do multichannel home sleep tests.  PSG provides electroencephalographic information regarding arousals, yet this information has high interpreter variability, and ultimately diagnoses are made first by the respiratory information, second by the patient’s history and physical examination, and third by the oximetry recordings. So in fact, electroencephalograms and arousals make little

Fig. 10. An overnight multichannel home sleep test for the 47-year-old patient in case 2. The patient slept for 6 hours and 27 minutes. The Apnea Index was 5.5 events per hour, Hypopnea Index was 10.9 events per hour, and Apnea Hypopnea Index was 16.5 events per hour. He had 3.6 obstructive events per hour and 1.4 central events per hour. The Oxygen Desaturation Index was 12.8 events per hour, the Average Oxygen Desaturation was 94.1% (normal is 96%), and the lowest oxygen saturation was 87%. The impression is moderate SDB.

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Fig. 11. History and physical for a 43-year-old male referred for snoring and drug-resistant hypertension.

difference. Sleep stages, time, and efficiency are useful information, but not necessary to make a diagnosis.  CPAP pressures are determined by a single night 2- to 4-hour manual of a CPAP pressure calculated to last the patient for the upcoming years with no regard to night-to-night variability or pressure requirement changes overtime.

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Fig. 12. Multichannel home sleep test shows an Apnea Hypopnea Index of 66. The patient’s average oxygen desaturation is 94%, which is below normal ranges during sleep.

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Fig. 13. The oxygen tracings for the 43-year-old male patient with an Apnea Hypopnea Index of 66 show significant desaturations during recurrent apneic events.

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Table 3 Home sleep diagnostic devices, manufacturers, and websites Device

Manufacturer

URL

ApneaLink Apnea Risk Evaluation System Apnoescreen Compas Edentec Embletta LifeShirt MESAM IV Monet Novasom QSG Poly-MESAM Remmers Sleep Recorder (formerly SnoreSat) Sandman SNAP Somnocheck Somnotrac Pro Somte´ Stardust II WatchPAT 100

ResMed Advanced Brain Monitoring Viasys Health care Embla SleepMed Embla VivoMetrics MAP Embla Sleep Solutions MAP SagaTech

http://www.resmed.com http://www.b-alert.com

Puritan Bennett Snap Laboratories Weinmann Viasys Health Care Compumedics Respironics Itamar Medical

http://www.sandmansleep.com http://www.snaplab.com http://www.weinmann.de http://www.viasyshealthcare.com http://www.compumedics.com http://www.respironics.com http://www.itamar-medical.com

http://www.viasyshealthcare.com http://www.embla.com http://www.sleepmed.md http://www.embla.com http://www.lifeshirt.com http://www.map-med.com http://www.embla.com http://www.sleep-solutions.com http://www.map-med.com http://www.sagatech.ca

Home sleep tests:     

Use the same respiratory equipment and analysis as do PSG. Use the same oximetry equipment and analysis as do PSG. Use the same chest and abdominal equipment as do PSG. Use the same position sensors as do PSG. Report the same AHI except uses a denominator of total time in bed, rather than total time asleep, which for those who have SDB seems not to be an issue.

Home sleep tests have several advantages over polysomnograms:  They are performed in the patient’s own home, bed, and privacy.  The wires, leads, and so forth are less numerous, and the patient’s sleep is more comfortable and therefore more indicative of their normal sleep.  Home sleep tests are substantially less expensive: 2% to 30% the cost of PSG.  Home sleep diagnostic dispensing and titration is easier than PSG lab setups and therefore can be performed by a greater number of practitioners, including all pulmonologists, cardiologists, anesthesiologists, and head and neck surgeons. The entire controversy comes down to a single issue: If in fact PSG is the most accurate sleep diagnostic paradigm (this issue is easily argued to the

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Table 4 Studies demonstrating strong correlations between polysomnography and home sleep testing

Author

1991 1995 1995 1996 1996 1997 1997 1999 2000 2000 2000

Edentec 25 PolyG 104 Autoset 31 Autoset 44 Autoset 36 Edentec 23 Autoset 67 Embletta 97 Autoset 95 Sibel Home 116 Edentec 62

20 d 26 34 27 19 58 d 79 65 58

5 d 5 10 9 4 9 d 16 51 4

53 d 46 52 45 50 51 d 53 47 53

31 20 5 d 104 0 30 31 0 29 44 0 28 28 0 30 23 31 67 0 d 79 0 31 95 0 26 116 0 25–28 62 0

2001 2003 2003 2003 2003 2004 2004 2003 2003 2006

BedBugg 42 NovaSom 51 WatchPAT 102 LifeShirt 10 Embletta 101 WatchPAT 29 SNAP 60 ApneaLink 50 WatchPAT 30 WatchPAT 98

d 38 78 10 80 21 25 d 19 55

d 13 69 d 21 8 35 d 11 43

d 52 41 d 48 43 45 d 47 60

d 30 27 d 32 34 36 d 31 28

42 51 102 0 40 29 60 50 30 98

0 51 14 10 61 29 0 0 0 0

37 d 25 19 19 27 26 43 9.5 d

36 d d 17 18 25 30 25 34 6.9 d

0.96 0.97 0.85 0.93 0.92 d 0.95 0.9 0.87 d d

86% 86% 100% 100% 100% d 97% 97% 92% 95% 96%

95% 95% 92% 87% 92% d 77% 93% 79% 92% d

92% 92% d d 86% d d d d d d

USA Canada UK France Ireland UK Switzerland Germany France Spain Spain

d d d 28 d 32 27 d 23 25

d d d 27 d 34 26 d 23 27

0.96 d 0.87 0.97 0.98/0.74 d 0.92 0.98 0.87 0.9

86% 95/91 d 86% d 91% 98% 100% 91% d

95% 91/83 d 100% d 86% 40% 88% 84% d

d d d d d d 95% d d d

USA USA Israel USA UK USA USA Germany USA Sweden

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Redline, et al [29] Man & Kang [30] Bradley, et al [31] Fleury, et al [32] Kiely, et al [33] Whittle, et al [34] Gugger [35] Alymow, et al [36] Mayer, et al [37] Ballester, et al [38] Jimenez-Gomez, et al [39] Claman, et al [40] Reichart, et al [41] Bar, et al [42] Coyle, et al [43] Dingli, et al [44] Pittman, et al [45] Su, et al [46] Wang, et al [47] Ayas, et al [48] Zou, et al [49]

AHI# A AHI- Sleep Year Equipment Patients Male Female Age BMI Syn Syn PSG Test Correlation Sensitivity Specificity Accuracy Country

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converse), are home sleep tests sufficiently accurate to be used for routine sleep apnea/SDB cases? It seems that the primary focus of discussion pro PSG is the efficacy of PSG versus home sleep testing. There are numerous validation studies of home sleep testing versus PSG. Currently, there are at least 19 studies including 1173 patients that demonstrate excellent correlation between multichannel home sleep tests and PSG. These are shown in Table 4 [29–49]. Further strengthening the urgency for improved capability to diagnose SDB is the recognition that SDB can result in an early and untimely death. A study published in the Journal of Internal Medicine in 1991 brought this to the world’s attention, reporting that nighttime cardiovascular death was more common among those who snored than for those who did not: ‘‘Habitual snoring was found to be a risk factor for morning death (P!.01)’’ [50]. The European Respiratory Journal in 2005 reported the hazard of mortality in sleep apnea increases with apnea severity as indexed by the Respiratory Disturbance Index [51]. The New England Journal of Medicine in 2005 also reported: ‘‘People with obstructive sleep apnea have a peak in sudden death from cardiac causes during the sleeping hours, which contrasts strikingly with the nadir of sudden death from cardiac causes during this period in people without obstructive sleep apnea and in the general population’’[52]. The authors’ conclusions are:  Sleep testing is easily and accurately performed by numerous home sleep test paradigms.  Home sleep testing reduces cost.  Home sleep testing improves access.  Home sleep testing is reimbursed by private sector ‘‘Fee For Service Insurers.’’  Multichannel home sleep testing is currently approved by CMS carriers in areas where in-lab PSG is not available. Home sleep testing is used by other health programs such as the VA Health care System and by Kaiser Permanente.  Home sleep testing should be approved as a valid SDB test paradigm.

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