Nurit Fox

Diagnosis and Initial Management of Obstructive Sleep Apnea without Polysomnography: A Randomized Validation Study

Context Overnight polysomnography in a sleep laboratory is normal practice for diagnosing obstructive sleep apnea (OSA) but it is expensive and can delay diagnosis. Contribution The authors combined standard clinical scales and overnight home oximetry to ensure a pretest probability of OSA of 90% or greater. Sixty-eight patients were randomly assigned to usual care (polysomnography obtained before continuous positive airway pressure [CPAP]) or ambulatory management (start CPAP without doing polysomnography). After 3 months, the 2 groups had the same results on overnight polysomnography. Cautions The study was done in a single tertiary care center. Implications Most patients with a probability of OSA of 90% or greater do not require polysomnography before starting CPAP. The Editors Symptomatic obstructive sleep apnea is a common, underdiagnosed condition that occurs in 4% of men and in 2% of women (1). Patients with obstructive sleep apnea have considerable comorbid conditions, including excessive daytime sleepiness; concentration difficulties; and an increased risk for motor vehicle accidents, hypertension (2), coronary artery disease, and strokes. Obstructive sleep apnea may result in a systemic inflammatory state that predisposes the patient to cardiac and cerebrovascular conditions (3). Continuous positive airway pressure (CPAP) is an effective treatment that is commonly prescribed for symptomatic patients with obstructive sleep apnea: It is cost-effective (4) and reduces daytime sleepiness, rates of motor vehicle accidents, and blood pressure. The American Thoracic Society (5) and the American Academy of Sleep Medicine (6) recommend supervised polysomnography (PSG) in the sleep laboratory over 2 nights for diagnosis of obstructive sleep apnea and initiation of CPAP. This approach to a highly prevalent condition results in inevitable discrepancies between the demand for services and the current capacity of sleep laboratories (7). Various strategies have been proposed to expedite diagnosis and treatment for obstructive sleep apnea (8). Predictive algorithms (915) and widespread use of overnight home monitoring, such as oximetry, have improved access to diagnostic testing (1622). Several algorithms have been used to determine optimal CPAP (23, 24). Ambulatory use of autotitrating CPAP machines is effective in determining therapeutic CPAP (25) and as a treatment method. To our knowledge, this is the first study to examine a combined ambulatory diagnostic and treatment algorithm without PSG in initial management of obstructive sleep apnea. To do so, we performed 2 parallel validation studies: 1) a cross-sectional study in patients screened by the diagnostic algorithm to test its use in identifying high-probability patients using PSG as the gold standard, and 2) a randomized trial of PSG versus ambulatory CPAP titration in high-probability patients identified by the diagnostic algorithm. Our study asked whether the conventional PSG approach was superior to the ambulatory approach in terms of controlling obstructive sleep apnea as measured by the apneahypopnea index (AHI) on CPAP after 3 months of treatment. We also wanted to determine whether there was any difference between the 2 management strategies in terms of sleepiness, quality of life, treatment adherence, and CPAP after 3 months of treatment. Methods Study Design We designed a randomized, controlled, open-label clinical trial to compare PSG with an ambulatory algorithm for titration of effective CPAP in patients with a high probability of moderate to severe obstructive sleep apnea. Patient Selection Participants were recruited from among adult patients referred from the catchment area of the Sleep Disorders Program at University of British Columbia Hospital, Vancouver, British Columbia, Canada, between May 2004 and November 2005, for assessment of suspected obstructive sleep apnea. Consecutive patients who, on the basis of a routine clinical evaluation by their sleep physician, were suspected of having moderate to severe obstructive sleep apnea, met the inclusion criteria, and were referred for possible participation in the trial, were considered for recruitment. Eligible patients had a high pretest probability of moderate to severe obstructive sleep apnea, were medically stable, and were not taking any sedative medications. We excluded patients who were pregnant or who had abnormal results on spirometry (predicted forced vital capacity or FEV1 <70%); a known cause of daytime sleepiness; a major psychiatric disorder; a life-threatening comorbid illness, such as unstable coronary artery disease or chronic lung disease; a motor vehicle accident attributable to hypersomnolence in the preceding 5 years; previous treatment for obstructive sleep apnea; a contraindication to nasal CPAP therapy; or the inability to provide informed consent. Each eligible patient provided written informed consent, and our institutional ethics review committees approved the protocol. Patients were enrolled by the research coordinator who collected the baseline data. Determining Pretest Probability High-probability patients were identified by sequential application of the Epworth Sleepiness Scale (ESS), Sleep Apnea Clinical Score (SACS) (11), and overnight oximetry in the home. The range of possible scores on the ESS is 0 to 24. In a retrospective case series of all patients (n= 798) referred to our sleep clinic with suspected obstructive sleep apnea who had a full diagnostic overnight PSG between 1 January 2001 and 31 December 2001 (26), the prevalence of moderate to severe obstructive sleep apnea (AHI >15/h) was 49% among patients with an ESS score of 10 or greater. The SACS is a screening tool based on snoring, witnessed episodes of apnea, neck circumference, and systemic hypertension that can be used to calculate likelihood ratios for the presence of obstructive sleep apnea (11). A score of 15 or greater gives a likelihood ratio of 4.45 of having moderate to severe sleep apnea (11). The Remmers Sleep Recorder (SagaTech Electronics Inc., Calgary, Alberta, Canada) is an easy-to-use, multichannel portable device that measures oxygen saturation, respiratory effort, airflow, snoring, and leg movements. This device calculates a respiratory disturbance index (RDI) on the basis of oxygen desaturation events. An RDI of 15/h or greater measured by the Remmers Sleep Recorder has a sensitivity of 98% and a specificity of 88% for diagnosis of moderate to severe obstructive sleep apnea, giving a likelihood ratio of 8.1 (18). Starting with pretest odds of approximately 1:1 on the basis of an ESS score of 10 or greater, we used Bayes theorem and assumed no interaction between components of the algorithm. The combined likelihood ratio conditional on a SACS of 15 or greater and an oximetry RDI of 15/h or greater yielded an estimated pretest probability of moderate to severe obstructive sleep apnea greater than 95%. Protocol Before randomization, all recruited patients completed the Sleep Apnea Quality of Life Index (SAQLI)a comprehensive survey with a high degree of internal consistency, face validity, and construct validity designed to measure outcomes of clinical trials in sleep apnea (27, 28). All patients received a one-on-one orientation and education session from a dedicated CPAP coordinator who provided information in a standardized fashion regarding nasal CPAP therapy. This session included mask fitting and a trial of CPAP while the patient was awake to ensure that he or she could tolerate the device (Appendix). The CPAP coordinator randomly assigned patients to standard PSG or the ambulatory algorithm (Figure 1), using a stratified block randomization with a block size of 20. The stratification factors were an ESS score less than 15 versus an ESS score 15 or greater and oximetry RDI less than 30 episodes per hour versus RDI 30 episodes per hour or greater. Four large envelopes were prepared, 1 for each block. There were 20 folded cards in each envelope, 10 for the PSG group and 10 for the ambulatory group. Patients who consented to participate were assigned to a block according to their ESS and RDI scores. Each patient picked 1 card from the designated envelope; the CPAP coordinator noted the treatment allocation and destroyed the card. Blinding patients to their treatment allocation was not possible, but all patients were treated in an identical manner, including follow-up, aside from the interventions being studied. The ResMed AutoSet Spirit (ResMed Inc., Sydney, Australia) autotitrating CPAP machine was used in all patients. Together with the ResMed Autoscan software, this device is capable of storing and downloading data on compliance; mask leak; and CPAP, including the 95th percentile pressure (29)the pressure at or below which the patient spent 95% of the time. Final CPAP was determined according to treatment group. Figure 1. Design of the clinical study. CPAP = continuous positive airway pressure; ESS = Epworth Sleepiness Scale; PSG = polysomnography; SAQLI = Sleep Apnea Quality of Life Index. Polysomnography Group A trained technologist supervised PSG. Obstructive sleep apnea was confirmed during a regularly scheduled overnight PSG in the sleep laboratory at our hospital. Final CPAP was determined according to a standard protocol during a CPAP titration PSG performed on the following night (Appendix). There was no subsequent adjustment to the fixed CPAP in the PSG group. Ambulatory Group The AutoSet Spirit was set to autotitrate at pressures between 4 and 20 cm H2O. After being used for 1 week, the ResMed Autoscan software was interrogated for efficacy data, including CPAP, mask leak, residual respiratory events, and use. The 95th percentile pressure was taken as the initial effective pressure if no residual sleep-disordered breathing was identified. The patient continued treatment at this pressure in fixed CPAP mode for another week. On days 6 and 13, overnight oximetry using

Risk and severity of motor vehicle crashes in patients with obstructive sleep apnoea/hypopnoea

Background: Obstructive sleep apnoea/hypopnoea (OSAH) appears to be associated with an increased risk of motor vehicle crashes (MVCs). However, its impact on crash patterns, particularly the severity of crashes, has not been well described. A study was undertaken to determine whether OSAH severity influenced crash severity in patients referred for investigation of suspected sleep-disordered breathing. Methods: Objective crash data (including the nature of crashes) for 783 patients with suspected OSAH for the 3 years prior to polysomnography were obtained from provincial insurance records and compared with data for 783 age- and sex-matched controls. The patient group was 71% male with a mean age of 50 years, a mean apnoea-hypopnoea index (AHI) of 22 events/h and a mean Epworth Sleepiness Scale score of 10. Results: There were 375 crashes in the 3-year period, 252 in patients and 123 in controls. Compared with controls, patients with mild, moderate and severe OSAH had an increased rate of MVCs with relative risks of 2.6 (95% CI 1.7 to 3.9), 1.9 (95% CI 1.2 to 2.8) and 2.0 (95% CI 1.4 to 3.0), respectively. Patients with suspected OSAH and normal polysomnography (AHI 0–5) did not have an increased rate of MVC (relative risk 1.5 (95% CI 0.9 to 2.5), p = 0.21). When the impact of OSAH on MVC associated with personal injury was examined, patients with mild, moderate and severe OSAH had a substantially higher rate of MVCs than controls with relative risks of 4.8 (95% CI 1.8 to 12.4), 3.0 (95% CI 1.3 to 7.0) and 4.3 (95% CI 1.8 to 8.9), respectively, whereas patients without OSAH had similar crash rates to controls with a relative risk of 0.6 (95% CI 0.2 to 2.5). Very severe MVCs (head-on collisions or those involving pedestrians or cyclists) were rare, but 80% of these occurred in patients with OSAH (p = 0.06). Conclusion: Patients with OSAH have increased rates of MVCs, and disproportionately increased rates of MVCs are associated with personal injury.

The Impact of a Telemedicine Monitoring System on Positive Airway Pressure Adherence in Patients with Obstructive Sleep Apnea: A Randomized Controlled Trial

STUDY OBJECTIVES First-line therapy for patients with moderate to severe obstructive sleep apnea (OSA) is positive airway pressure (PAP). Although PAP is a highly efficacious treatment, adherence to PAP is still a substantial clinical problem. The objective of this study was to determine whether PAP adherence can be improved with a telemedicine monitoring system. DESIGN A nonblinded, single-center, randomized controlled trial that compared standard PAP treatment versus PAP treatment and a telemedicine monitoring system SETTING University sleep disorders program in British Columbia, Canada PATIENTS Adult patients (≥ 19 yr of age) with moderate to severe OSA (apnea hypopnea index (AHI) ≥ 15 events/hr determined by polysomnography) prescribed PAP INTERVENTIONS: Patients were randomized to either standard care with an autotitrating PAP machine or an autotitrating PAP machine that transmitted physiologic information (i.e., adherence, air leak, residual AHI) daily to a website that could be reviewed. If problems were identified from information from the website, the patient was contacted by telephone as necessary. MEASUREMENTS PAP adherence after 3 mo, subjective sleep quality, and side effects RESULTS Seventy-five patients were enrolled; 39 were randomized to telemedicine and 36 to standard care. The mean age ± standard deviation (SD) was 53.5 ± 11.2 yr, mean AHI was 41.6 ± 22.1 events/hr, and 80% of patients were male. After 3 mo, mean PAP adherence was significantly greater in the telemedicine arm (191 min per day) versus the standard arm (105 min per day; mean difference = 87 min, 95% confidence interval (CI): 25-148 min, P = 0.006, unpaired t test). On days when PAP was used, mean adherence was 321 min in the telemedicine arm and 207 min in the standard arm (difference = 113 min, 95% CI: 62-164 min, P < 0.0001). Significant independent predictors of adherence included age, baseline Epworth Sleepiness Scale score, and use of telemedicine. On average, an additional 67 min of technician time was spent on patients in the telemedicine arm compared with the standard arm (P = 0.0001). CONCLUSIONS PAP adherence can be improved with the use of a web-based telemedicine system at the initiation of treatment.

Residual sleep apnea on polysomnography after 3 months of CPAP therapy: Clinical implications, predictors and patterns

OBJECTIVE We sought to determine the clinical implications, predictors and patterns of residual sleep apnea on continuous positive airway pressure (CPAP) treatment in patients with moderate-to-severe obstructive sleep apnea (OSA). METHODS We performed a post hoc secondary analysis of data from a previously reported randomized trial. Sleepy patients with a high risk of moderate-to-severe OSA identified by a diagnostic algorithm were randomly assigned to standard CPAP titration during polysomnography (PSG) or ambulatory titration using auto-CPAP and home sleep testing. We observed them for 3 months and measured apnea-hypopnea index (AHI) on CPAP, Epworth sleepiness scale (ESS), sleep apnea quality of life index (SAQLI), CPAP pressure and objective CPAP compliance. RESULTS Sixty-one patients were randomized, 30 to the PSG group and 31 to the ambulatory group. Fifteen patients (25%) had residual sleep apnea (AHI > 10/h on CPAP) with similar proportions in the PSG (7/30) and ambulatory (8/31) groups. Baseline variables including age, body mass index (BMI), ESS, SAQLI, respiratory disturbance index (RDI) and CPAP pressure did not differ between the groups. Outcomes including compliance were worse in patients with residual sleep apnea. Periodic breathing was prevalent among patients with residual sleep apnea. CONCLUSIONS Residual sleep apnea is common in patients with moderate-to-severe OSA, despite careful CPAP titration, and is associated with worse outcomes.

Epidemiology of Sleep Disturbances and Cardiovascular Consequences.

It is increasingly recognized that disruption of sleep and reduced amounts of sleep can have significant adverse cardiovascular consequences. For example, obstructive sleep apnea (OSA) is a common underdiagnosed disorder characterized by recurrent nocturnal asphyxia resulting from repetitive collapse of the upper airway; this leads to repetitive episodes of nocturnal hypoxemia and arousal from sleep. Risk factors for disease include obesity, increased age, male sex, and family history. In epidemiologic studies, OSA appears to be an independent risk factor for cardiovascular disease (CVD), and treatment is associated with better outcomes. Habitual short sleep duration is common in todays society. In epidemiologic studies, short sleep duration is associated with a number of adverse health effects, including all-cause mortality, weight gain, and incident CVD. Given the links between sleep disorders and adverse health outcomes, obtaining adequate quality and amounts of sleep should be considered a component of a healthy lifestyle, similar to good diet and exercise.

Mandibular advancement splint as short-term alternative treatment in patients with obstructive sleep apnea already effectively treated with continuous positive airway pressure.

STUDY OBJECTIVES CPAP is used as the first-line treatment for patients with severe OSA, but this machine is not always feasible to use on the long term. We performed a clinical trial to determine whether patients with OSA could use a mandibular advancement splint (MAS) as a short-term treatment alternative to CPAP. METHODS Twenty-two patients adherent with CPAP therapy were recruited to the study. Each patient used the MAS for approximately 4 months. The transition between CPAP to MAS was gradual, and patients were asked to start using MAS together with CPAP during the MAS titration until subjective improvement or maximum mandibular advancement was achieved. Sleepiness (ESS), quality of life (SAQLI), and polysomnography were recorded prior to and after MAS titration. Patients recorded CPAP or MAS usage for the following 3 months. RESULTS Seven women and 12 men with a mean age of 53.8 (± 12.1) years and mean body mass index of 28.1 (± 4.8) kg/m² completed the clinical trial. Prior to MAS, CPAP adherence was 5.8 h/night. AHI decreased significantly with MAS use compared to baseline (30.7 ± 23.1 vs 13.2 ± 11; p < 0.01). Fourteen patients (74%) had > 50% decrease in their AHI, while 2 patients had an increase in their AHI. There were no significant differences in SAQLI between MAS and CPAP treatment, while ESS decreased significantly on MAS. MAS self-reported usage was correlated with treatment efficacy (r = 0.52; p < 0.05). Seventy-five percent of the patients reported being sufficiently satisfied with MAS to continue to use it as an alternative short-term therapy. CONCLUSIONS MAS partially or completely reduced sleep disordered breathing in the majority of selected, successfully CPAP-treated severe OSA patients. Many patients can probably effectively use MAS as a short-term treatment alternative to CPAP.