Accuracy of autotitrating CPAP to estimate the residual Apnea–Hypopnea Index in patients with obstructive sleep apnea on treatment with autotitrating CPAP

Polysomnographic evaluation of obstructive sleep apnea treatment with fixed pressure CPAP determined by formula

PURPOSE

The use of continuous positive airway pressure (CPAP) is one of the therapeutic modalities for obstructive sleep apnea (OSA). Manual titration polysomnography and the 90th or 95th percentiles of pressure titrated by automatic CPAP (APAP) are the current standard for determining fixed pressure. Pressures programmed at an arbitrary fixed value, or at preset values based on body mass index (BMI) or by predictive formulas, are presented as alternative forms. This study aimed to evaluate the residual apnea-hypopnea index (r-AHI) in polysomnography with CPAP therapy using pressure determined by formula and assess its feasibility to start treatment.

METHODS

Patients referred for CPAP therapy were followed up in three outpatient assessments and underwent polysomnography study with pressure CPAP obtained by formula.

RESULTS

The study sample consisted of 80 patients, 41 women; age 58.6 ± 11.3 years, BMI 34.1 ± 7.5 kg/m² and cervical circumference 42.0 ± 4.2 cm. Most patients (74%) had severe OSA and Epworth sleepiness scale (ESS) of 12.0 ± 5.7 points. The calculated average pressure was 7.8 ± 2.1 cmH₂O. Polysomnography studies showed an r-AHI of 6.1 ± 5.2 events/h and reduction of 84% from baseline AHI. The r-AHI in the REM-supine was 8.4 ± 9.9 events/h. At 30- and 120-day follow-up assessment, adherence to CPAP was 78% and 75% and the ESS score was 6.9 and 6.1 points, respectively.

CONCLUSION

Results suggest that a formula provides an effective initial pressure in the majority of patients (73%). This simplified approach appears to be a viable alternative, with reductions in waiting lists and time from diagnosis to initiation of therapy.

APAP, BPAP, CPAP, and New Modes of Positive Airway Pressure Therapy

Positive airway pressure (PAP) is the primary treatment of sleep-disordered breathing including obstructive sleep apnea, central sleep apnea, and sleep-related hypoventilation. Just as clinicians use pharmacological mechanism of action and pharmacokinetic data to optimize medication therapy for an individual, understanding how PAP works and choosing the right mode and device are critical to optimizing therapy in an individual patient. The first section of this chapter will describe the technology inside PAP devices that is essential for understanding the algorithms used to control the airflow and pressure. The second section will review how different comfort settings including ramp and expiratory pressure relief and modes of PAP therapy including continuous positive airway pressure (CPAP), autotitrating CPAP, bilevel positive airway pressure, adaptive servoventilation, and volume-assured pressure support control the airflow and pressure. Proprietary algorithms from several different manufacturers are described. This chapter derives its descriptions of algorithms from multiple sources including literature review, manufacture publications and websites, patents, and peer-reviewed device comparisons and from personal communication with manufacturer representatives. Clinical considerations related to the technological aspects of the different algorithms and features will be reviewed.

A longitudinal study of the accuracy of positive pressure therapy machine-detected apnea-hypopnea events

STUDY OBJECTIVES

During positive airway pressure (PAP) therapy for sleep apnea syndromes, the machine detected respiratory event index (REI_FLOW) is an important method for clinicians to evaluate the beneficial effects of PAP. There are concerns about the accuracy of this detection, which also confounds a related question-how common and severe are residual events on PAP.

METHODS

Subjects with OSA who underwent a split night polysomnography were recruited prospectively. Those treated with PAP and tracked by the EncoreAnywhere system were analyzed. The ones who stopped PAP within one month were excluded for this analysis. Compliance, therapy data and waveform data were analyzed. Machine detected versus manually scored events were compared at the 1st, 3rd, 6th and 12th month from PAP initiation. Logistic regression was used to determine factors associated with a high REI_FLOW difference.

RESULTS

One hundred and seventy-nine patients with a mean age 59.06 ± 13.97 years old, median body mass index 33.60 (29.75-38.75) kg/m², and median baseline AHI 46.30 (31.50-65.90) times/hour were included. The difference between the machine detected REI_FLOW and manually scored REI_FLOW was 10.72 ±8.43 in the first month and remained stable for up to 12 months. Male sex and large leak ≥ 1.5% were more frequent in patients who had an REI_FLOW difference of ≥ 5 / hour of use. A titration arousal index ≥ 15/ hour of sleep, and higher ratio of unstable to stable breathing were also associated with an REI_FLOW difference ≥ 5 times/hour of use.

CONCLUSIONS

There is a substantial and sustained difference between manual and automated event estimates during PAP therapy, and some associated factors were identified.

Feasibility and efficacy of active remote monitoring of home ventilation in pediatrics

BACKGROUND

Non-invasive positive airway pressure (PAP) therapy is used to treat children with sleep-disordered breathing. Effective management requires good adherence. In response to the problem of reduced adherence over time, a pilot study using ventilators equipped with technology to remotely monitor home adherence was undertaken.

METHODS

From July 2019, children requiring PAP therapy consented for remote monitoring. Data collected included ventilator usage, apnea-hypopnea index (AHI), and mask leak. Parents were contacted on Days 14, 42, and 90 post-establishment. A proforma was used to assess parental understanding and ways to improve therapy adherence. A parental feedback questionnaire was completed on Day 90 of the study.

RESULTS

Median nightly PAP usage over 90-day post-establishment was 6.58 h (interquartile range: 2.47-8.62); 60% of patients met criteria for good adherence (>4 h for >70% of nights). There was a decrease in median nightly usage in Week 1 (6.92 h) versus Week 12 (6.15 h), p =  0.04. Mask leak was higher in Week 1 (17.7 L/min) versus Week 12 (14.7 L/min), p =  0.053. There was no significant difference in AHI between Week 1 (2.7/h) versus Week 12 (2.3/h), p =  0.75. 45% of questionnaire respondents felt active remote monitoring positively influenced PAP usage, whilst 84% reported overall satisfaction with PAP therapy.

CONCLUSIONS

Remote monitoring technology has the potential to guide adjustments in PAP therapy, monitor and improve adherence in children, and reduce the burden of hospital-based review. Preliminary work shows high approval from parents.

Interpreting CPAP device respiratory indices in children

STUDY OBJECTIVES

An increasing number of children with obstructive sleep apnea (OSA) require treatment with continuous positive airway pressure (CPAP). This study aimed to determine whether automatic respiratory indices from a CPAP device accurately predict manually determined respiratory indices derived from overnight polysomnography (PSG) in children.

METHODS

Consecutive children undergoing manual CPAP titration PSG using a ResMed VPAP ST-A (S9) were included. The apnea-hypopnea index (AHI), apnea index (AI), and hypopnea index (HI) from automatic analysis of the CPAP device for that night (AHI_CPAP, AI_CPAP, and HI_CPAP) were compared with manually derived respiratory indices (RDI_PSG, OAHI_PSG, AI_PSG, and HI_PSG) using the Wilcoxon matched-pairs signed-ranks test.

RESULTS

Forty-six children (32 boys; median age, 13.5 years; range, 4.6-20.0 years) were included. There was no difference between RDI_PSG and AHI_CPAP (P = .6) nor between HI_PSG and HI_CPAP (P = .2). AI_PSG was significantly lower than AI_CPAP (mean difference -1.3 events/hr, P < .001). AI_PSG and AI_CPAP were strongly correlated (r² = .72, P < .01), but the CPAP machine overestimated the number of apneas at higher AIs. OAHI_PSG was significantly lower than AHI_CPAP (P = .003) but strongly correlated (r² = .87, P < .01). The CPAP device significantly underestimated the number of hypopneas at higher indices. Using the manually scored OAHI_PSG of ≥5 events/hr to define significant residual OSA, the AHI_CPAP had a high specificity (0.95) but low sensitivity (0.20).

CONCLUSIONS

The ResMed S9 respiratory indices are not accurate enough to guide treatment decisions in children; in particular, they do not rule out the presence of residual OSA in children that remain symptomatic on CPAP. A low AHI_CPAP is reassuring in the context of a stable patient but may miss ongoing hypopneas.

Use of polysomnography and home sleep apnea tests for the longitudinal management of obstructive sleep apnea in adults: an American Academy of Sleep Medicine clinical guidance statement

INTRODUCTION

Obstructive sleep apnea is an important and common disorder with associated health risks. Assuring successful longitudinal management is vital to patient health and sleep-related quality of life. This paper provides guidance from the American Academy of Sleep Medicine (AASM) regarding the use of polysomnography (PSG) and home sleep apnea tests (HSATs) after a diagnosis of obstructive sleep apnea has been established and, in most cases, treatment implemented.

METHODS

The AASM commissioned a task force of five sleep medicine experts. A literature search was conducted to identify studies that included adult patients with OSA who underwent follow-up PSG or an HSAT. The task force developed clinical guidance statements based on a review of these studies and expert opinion. The AASM Board of Directors approved the final clinical guidance statements.

CLINICAL GUIDANCE STATEMENTS

The AASM supports the following clinical guidance statements on indications for follow-up PSG and HSAT in adult patients with OSA. 1. Follow-up PSG or HSAT is not recommended for routine reassessment of asymptomatic patients with obstructive sleep apnea on PAP therapy, however, follow-up PSG or HSAT can be used to reassess patients with recurrent or persistent symptoms, despite good PAP adherence. 2. Follow-up PSG or HSAT is recommended to assess response to treatment with non-PAP interventions. 3. Follow-up PSG or HSAT may be used if clinically significant weight gain or loss has occurred since diagnosis of OSA or initiation of its treatment. 4. Follow-up PSG may be used for reassessment of sleep-related hypoxemia and/or sleep-related hypoventilation following initiation of treatment for OSA. 5. Follow-up PSG or HSAT may be used in patients being treated for OSA who develop or have a change in cardiovascular disease. 6. Follow-up PSG may be used in patients with unexplained PAP device-generated data. The ultimate judgment regarding propriety of any specific care must be made by the clinician, in light of the individual circumstances presented by the patient, available diagnostic tools, accessible treatment options and resources.

Reliability of automatic detection of AHI during positive airway pressure treatment in obstructive sleep apnea patients: A "real-life study"

INTRODUCTION

Automatic event detection (AED) of residual apnea-hypopnea index (AHI) by ventilators is a current practice in sleep and mechanical ventilation Units but this methodology has not been validated in an unselected population of OSA patients. Aim of the present study was to assess in a "real-life" condition the reliability of AED during PAP therapy by the in-built software compared to full polysomnography during follow-up.

METHODS

We enrolled 300 OSA patients (105 F; AHI 45.3 ± 27.8) already on Positive airway pressure (PAP) therapy: 53% of the patients were on CPAP while other modalities were used in the rest of the sample.

RESULTS

Overall, the built-in software identified residual obstructive AHI (AHIPAP) > 5, 10 or 15 in 18.7, 8.6 or 4.6% of patients, respectively. By using AHIPAP, 28.4% of patients were wrongly classified as "well controlled" despite a residual AHIPSG>5 (6% considering a residual AHIVENT >15); 7% of patients were classified as not controlled while AHIPSG was <5 (1.4% considering a residual AHIVENT >15). Type of ventilation, ventilator parameters, adherence to treatment and level of baseline or follow-up Epworth Sleepiness Scale score were similar between groups. The sensitivity and positive predicted values were very low. Positive likelihood ratio appears adequate only for residual AHIPAP ≥10, but negative likelihood ratio was inconclusive for all the cut-off considered.

DISCUSSION

The results of the present study suggest a more cautious approach in the follow-up of OSA patients, since a protocol based only on AED detection and symptoms assessment may not be accurate especially for AHIPAP<15.

Continuous Positive Airway Pressure-Mandibular Advancement Device Combination Therapy for Moderate-to-Severe Obstructive Sleep Apnea: A Preliminary Study

Objectives  The purpose of this pilot study was to determine whether compliance to auto-adjusting positive airway pressure (APAP) improves with the addition of a mandibular advancement device (MAD). Secondary outcome measures included were APAP pressure, subjective daytime sleepiness, apnea–hypopnea index (AHI), and mask leaks.

Setting and Sample Population  Participants included were diagnosed with moderate-to-severe obstructive sleep apnea (OSA) and became noncompliant to prescribed APAP. Thirteen participants with a mean age of 61.6 years were recruited for this study.

Materials and Methods  All participants were given a MAD to use with their APAP. Parameters measured included APAP pressure, AHI, mask leak reported via ResMed AirViewTM software, and self-reported daytime sleepiness (Epworth Sleepiness Scale [ESS]). A paired two-sample for mean t -test was performed to determine significance.

Results  The mean difference of pre- and postintervention APAP compliance was 23.1%, which was statistically significant ( p = 0.015). The mean APAP air pressures were unchanged. The difference between pre- and postintervention mean ESS scores was 1.4 and was statistically significant ( p = 0.027). The mean difference between pre- and postintervention AHI values and mask leak showed no significant difference.

Conclusion  This study showed that combination of APAP-MAD therapy, for patients with moderate-to-severe OSA who were noncompliant to APAP use, significantly increased compliance with APAP therapy, and significantly decreased the daytime sleepiness of participants.

Validating respiratory index of auto-titrating positive airway pressure device with polysomnography

PURPOSE

Positive airway pressure (PAP) devices have been widely used as the first line of treatment in obstructive sleep apnea (OSA). Most advanced PAP devices support the estimation of respiratory index (RI) using the patient's mask airflow. In addition to the compliance factor for PAP device use, which is important for monitoring patient sleep health, RI is also becoming important for monitoring. However, there are few reports that validate RI of a PAP device with polysomnography.

METHODS

Between January 2015 and December 2017, 50 participants were enrolled who were diagnosed with OSA and prescribed auto-titration PAP (APAP) devices. The RIs of participants were measured at night using APAP devices, concurrently with electroencephalography, respiratory inductance plethysmography sensors, and other polysomnographic sensors in a sleep laboratory. The respiratory-related data of APAP were prospectively analyzed with the manually scored polysomnographic data.

RESULTS

The apnea-hypopnea index and apnea index showed a statistically close relationship between the auto-scored respiratory data from the APAP device and the manually scored respiratory data from polysomnographic sensors. Obstructive apnea and central apnea indices showed relatively low correlations. The differences between the auto-scored RI and manually scored RI were influenced by BMI, waist circumference, weight, oxygen saturation, and respiratory distress indices of diagnostic polysomnographic factors.

CONCLUSIONS

The RIs of APAP devices have a tendency to be underestimated or mismatched when compared with polysomnography. Sleep specialists are advised to consider additional anthropometric and diagnostic factors to account for these differences during PAP treatment.

Use of the WatchPAT to detect occult residual sleep-disordered breathing in patients on CPAP for obstructive sleep apnea

STUDY OBJECTIVES

To determine the accuracy of the apnea-hypopnea index (AHI) as measured by continuous positive airway pressure (CPAP) machines by simultaneously employing a home sleep apnea testing device (WatchPAT 200, Itamar Medical, Israel [WPAT]) in patients suspected of having residual sleep-disordered breathing (SDB).

METHODS

Patients with new, recurrent, or worsening signs, symptoms, or comorbidities associated with obstructive sleep apnea underwent home sleep apnea testing using WPAT while simultaneously using CPAP at their usual prescribed settings. CPAP AHI and WPAT AHI, respiratory disturbance index, and oximetry readings were then compared.

RESULTS

We identified an elevated AHI with WPAT testing in nearly half of patients with clinically suspected residual SDB and a normal CPAP AHI. WPAT detected additional respiratory events as well, including rapid eye movement-related apneas, respiratory effort-related arousals, and hypoxemia.

CONCLUSIONS

WPAT AHI was significantly higher than simultaneous CPAP AHI in nearly half of those patients with clinically suspected residual SDB being treated with CPAP. Additional respiratory disturbances, including rapid eye movement-related respiratory events, respiratory effort-related arousals, and hypoxemia, were elucidated only with the use of the WPAT. Residual SDB may have potential clinical consequences, including reduced CPAP adherence, ongoing hypersomnolence, and other health-related sequelae. Simultaneous WPAT testing of patients with a normal CPAP AHI may represent a valuable tool to detect clinically suspected residual SDB or to ensure adequate treatment in high-risk patients with obstructive sleep apnea in general.

Comparison of 3-months treatment adherence and estimating residual apnea hypopnea index between home versus in-laboratory auto-titrating positive airway pressure titration

PURPOSE

We aimed to assess the accuracy of home titration in estimating apnea hypopnea index (AHI) and optimal pressure values and to compare improvements in subjective daytime sleepiness, sleep quality and quality of life, along with 3-months treatment adherence of patients that received at-home versus in-laboratory auto-titrating positive airway pressure (APAP) titration.

MATERIALS AND METHODS

In patients with a diagnosis of obstructive sleep apnea syndrome (OSAS), a study arm of laboratory attended APAP titration was compared with a study arm of home titration using an APAP device for three days. Subjective questionnaires were evaluated before and after 3 months of treatment.

RESULTS

Fifty-three patients with newly diagnosed OSAS were enrolled. There was a significant positive correlation between PSG AHI and APAP AHI (r_s  = 0.43, P = 0.003) and the fixed pressure for the APAP arm was positively correlated with the APAP PSG arm of the study (r_s  = 0.71, P < 0.001). When the Bland-Altman graphs were compared, it was seen that the measurements obtained by the APAP AHI method were 0.3 units higher than the PSG AHI measurements, and that the mean of the measurement differences between the two methods was not different than 0 (P [H₀ : Mean = 0] = 0.551). After 3 months of treatment, average nightly use was slightly higher in the APAP arm (P = 0.387).

CONCLUSIONS

The results indicate that both titration methods were not clinically inferior in terms of a fixed optimal pressure, residual events, 3-months treatment adherence and change in subjective sleepiness, sleep quality and quality of life after treatment.

The management, privacy and medico-legal issues of electronic CPAP data in Australia and New Zealand: Electronic CPAP data management in Australia and New Zealand

STUDY OBJECTIVE

Continuous Positive Airway Pressure (CPAP) is considered to be the gold standard treatment for obstructive sleep apnoea (OSA). CPAP monitoring systems allow tracking of patient CPAP adherence and treatment efficacy, by measuring residual sleep-disordered breathing, hours of CPAP use, and mask leak etc. The American Thoracic Society (ATS) published a position paper in 2013 highlighting issues of interpreting CPAP data such as a lack of consistency between CPAP manufacturers data algorithms, legal implications of CPAP data and implications for CPAP adherence. This paper extends on this work by investigating these issues in an Australasian context.

METHOD

A review of current literature on CPAP monitoring systems, privacy and security of CPAP data for major Australasian CPAP providers, and CPAP adherence was undertaken. A legal review was also commissioned for issues related to privacy and security of CPAP data.

RESULTS

CPAP manufacturers' utilize different algorithms for respiratory event detection and clinicians need to be aware the implications for interpreting CPAP data. Australasian CPAP manufacturers have created security/privacy policies with the intent to follow relevant legislation to protect patients' CPAP data, however they do need to be constantly reviewed and updated to avoid data breaches and changes to agreements. No guarantees can be provided by the Australasian Sleep Association on CPAP manufacturers' compliance with these policies and there is the potential for some degree of liability for physicians and CPAP providers associated with CPAP data. Lastly, providing patients with feedback on their CPAP usage and OSA management appears to have positive influence CPAP adherence.

CONCLUSIONS

CPAP data provides many opportunities to increase OSA patient care and to help patients self-manage this chronic condition. However, issues relating to lack of standardization of CPAP parameters, privacy, security, and legal implications will need to be managed in this changing technologic and clinical environment.

Validation of the System One RemStar Auto A-Flex for Obstructive Sleep Apnea Treatment and Detection of Residual Apnea-Hypopnea Index: A European Randomized Trial

STUDY OBJECTIVES

Autotitrating continuous positive airway pressure (CPAP) devices adjust pressure in response to changes in airflow and are an alternative to attended in-laboratory titration polysomnography (PSG) to determine optimal pressure levels. The aim of this study was to compare the performance of the System One RemStar Auto A-Flex (Philips Respironics, Murrysville, PA, USA) automatically adjusted positive airway pressure (APAP) mode to manually titrated, fixed pressure CPAP and to validate the device's breathing event detection capabilities against attended in-laboratory PSG.

METHODS

Sixty-one patients investigated in five centers for moderate to severe obstructive sleep apnea between May 2012 and June 2013 were invited to participate. Participants underwent two full-night attended polysomnograms in random order with manually titrated, fixed pressure CPAP versus APAP.

RESULTS

Fifty-three participants with a mean apnea-hypopnea index (AHI) of 45.9 ± 23 completed two sleep studies and were included in the analysis. There were significant but not clinically relevant differences between APAP and CPAP respectively: Apnea index [1.0 (2.8 ± 0.8), median (mean ± standard deviation)] versus [1.8 (5.3 ± 11.5)], p = 0.004; percentage of N1 sleep [12.3 (15.9 ± 0.5)] versus [14.3 (18.9 ± 12.7)], p = 0.028. AHI values differed between PSG [2.8 (5.5. ± 9.3)] and device [3.7 (6.0 ± 8.6)], p = 0.003). Regarding residual events detection, intraclass correlation coefficients for AHI were strong (0.956, p < 0.001) and the area under the curve was 0.988 (AHI cut-off value of 10).

CONCLUSIONS

The new APAP modality was effective and residual apnea-hypopnea indices calculated by the device strongly correlated to those assessed by PSG.

COMMENTARY

A commentary on this article appears in this issue on page 167.

Residual Events during Use of CPAP: Prevalence, Predictors, and Detection Accuracy

STUDY OBJECTIVES

To assess the frequency, severity, and determinants of residual respiratory events during continuous positive airway therapy (CPAP) for obstructive sleep apnea (OSA) as determined by device output.

METHODS

Subjects were consecutive OSA patients at an American Academy of Sleep Medicine accredited multidisciplinary sleep center. Inclusion criteria included CPAP use for a minimum of 3 months, and a minimum nightly use of 4 hours. Compliance metrics and waveform data from 217 subjects were analyzed retrospectively. Events were scored manually when there was a clear reduction of amplitude (≥ 30%) or flow-limitation with 2-3 larger recovery breaths. Automatically detected versus manually scored events were subjected to statistical analyses included Bland-Altman plots, correlation coefficients, and logistic regression exploring predictors of residual events.

RESULTS

The mean patient age was 54.7 ± 14.2 years; 63% were males. All patients had a primary diagnosis of obstructive sleep apnea, 26% defined as complex sleep apnea. Residual flow measurement based apnea-hypopnea index (AHIFLOW) > 5, 10, and 15/h was seen in 32.3%, 9.7%, and 1.8% vs. 60.8%, 23%, and 7.8% of subjects based on automated vs. manual scoring of waveform data. Automatically detected versus manually scored average AHIFLOW was 4.4 ± 3.8 vs. 7.3 ± 5.1 per hour. In a logistic regression analysis, the only predictors for a manual AHIFLOW > 5/h were the absolute central apnea index (CAI), (odds ratio [OR]: 1.5, p: 0.01, CI: 1.1-2.0), or using a CAI threshold of 5/h of sleep (OR: 5.0, p: < 0.001, CI: 2.2-13.8). For AHIFLOW > 10/h, the OR was 1.14, p: 0.03 (CI: 1.1-1.3) per every CAI unit of 1/hour.

CONCLUSIONS

Residual respiratory events are common during CPAP treatment, may be missed by automated device detection and predicted by a high central apnea index on the baseline diagnostic study. Direct visualization of flow data is generally available and improves detection.

All APAPs Are Not Equivalent for the Treatment of Sleep Disordered Breathing: A Bench Evaluation of Eleven Commercially Available Devices

STUDY OBJECTIVES

This study challenged on a bench-test the efficacy of auto-titrating positive airway pressure (APAP) devices for obstructive sleep disordered breathing treatment and evaluated the accuracy of the device reports.

METHODS

Our bench consisted of an active lung simulator and a Starling resistor. Eleven commercially available APAP devices were evaluated on their reactions to single-type SDB sequences (obstructive apnea and hypopnea, central apnea, and snoring), and to a long general breathing scenario (5.75 h) simulating various SDB during four sleep cycles and to a short scenario (95 min) simulating one sleep cycle.

RESULTS

In the single-type sequence of 30-minute repetitive obstructive apneas, only 5 devices normalized the airflow (> 70% of baseline breathing amplitude). Similarly, normalized breathing was recorded with 8 devices only for a 20-min obstructive hypopnea sequence. Five devices increased the pressure in response to snoring. Only 4 devices maintained a constant minimum pressure when subjected to repeated central apneas with an open upper airway. In the long general breathing scenario, the pressure responses and the treatment efficacy differed among devices: only 5 devices obtained a residual obstructive AHI < 5/h. During the short general breathing scenario, only 2 devices reached the same treatment efficacy (p < 0.001), and 3 devices underestimated the AHI by > 10% (p < 0.001). The long scenario led to more consistent device reports.

CONCLUSION

Large differences between APAP devices in the treatment efficacy and the accuracy of report were evidenced in the current study.

Detection of upper airway status and respiratory events by a current generation positive airway pressure device

STUDY OBJECTIVES

To compare a positive airway pressure (PAP) device's detection of respiratory events and airway status during device-detected apneas with events scored on simultaneous polysomnography (PSG).

DESIGN

Prospective PSGs of patients with sleep apnea using a new-generation PAP device.

SETTINGS

Four clinical and academic sleep centers.

PATIENTS

Forty-five patients with obstructive sleep apnea (OSA) and complex sleep apnea (Comp SA) performed a PSG on PAP levels adjusted to induce respiratory events.

INTERVENTIONS

None.

MEASUREMENTS AND RESULTS

PAP device data identifying the type of respiratory event and whether the airway during a device-detected apnea was open or obstructed were compared to time-synced, manually scored respiratory events on simultaneous PSG recording. Intraclass correlation coefficients between device-detected and PSG scored events were 0.854 for apnea-hypopnea index (AHI), 0.783 for apnea index, 0.252 for hypopnea index, and 0.098 for respiratory event-related arousals index. At a device AHI (AHIFlow) of 10 events/h, area under the receiver operating characteristic curve was 0.98, with sensitivity 0.92 and specificity 0.84. AHIFlow tended to overestimate AHI on PSG at values less than 10 events/h. The device detected that the airway was obstructed in 87.4% of manually scored obstructive apneas. Of the device-detected apneas with clear airway, a minority (15.8%) were manually scored as obstructive apneas.

CONCLUSIONS

A device-detected apnea-hypopnea index (AHIFlow) < 10 events/h on a positive airway pressure device is strong evidence of good treatment efficacy. Device-detected airway status agrees closely with the presumed airway status during polysomnography scored events, but should not be equated with a specific type of respiratory event.

Apnea burden: efficacy versus effectiveness in patients using positive airway pressure

BACKGROUND

Modern continuous positive airway pressure (PAP) machines track hours of use and residual respiratory events while on treatment. A substantial portion of sleep apnea patients are partially compliant, emphasizing the need to distinguish between PAP efficacy and PAP effectiveness in chronic management of patients with sleep apnea.

METHODS

We used a combination of three data sources to estimate the sleep apnea burden in a convenience cohort of PAP users from our clinics that were compliant based on Medicare criteria: self-reported habitual total sleep time, and PAP usage times with residual apnea-hypopnea index (AHI) from compliance downloads.

RESULTS

Assuming that the off-PAP time consists of baseline AHI severity, an estimated apnea burden was calculated to estimate PAP effectiveness. Whereas 70% of patients in our cohort showed machine AHI values <5/h, the apnea burden calculations revealed that only one-third of patients are predicted to have an effective AHI <5.

CONCLUSION

Estimating PAP effectiveness through the concept of apnea burden has implications for clinical care as well as research trials.

Comparing methods of respiratory event detection during the treatment of obstructive sleep apnea

Renewed focus on comparative effectiveness research presents a unique opportunity to develop optimal clinical management pathways for patients with obstructive sleep apnea. With this momentum comes the challenge of measuring treatment effect on sleep-disordered breathing, especially in large, multisite studies. In-laboratory polysomnography, the current gold standard sleep assessment of obstructive sleep apnea severity, is costly and imposes significant participant burden. Alternatives include home unattended sleep testing and overnight pulse oximetry recording. Research studies using positive airway pressure treatment have the additional option of using the information recorded by the patient's positive airway pressure device to assess treatment effectiveness. Recent research has shown relatively good agreement between manual identification of residual respiratory events in overnight in-laboratory polysomnography and the automatic event detection utilized in positive airway pressure machines. In addition to assessing the effects of interventions on sleep disordered breathing, obstructive sleep apnea-related comparative effectiveness studies need to assess the impact of the interventions on patient burden, cost of therapy, timeliness of care, improved quality of life and other clinically relevant outcomes.

An official American Thoracic Society statement: continuous positive airway pressure adherence tracking systems. The optimal monitoring strategies and outcome measures in adults

BACKGROUND

Continuous positive airway pressure (CPAP) is considered the treatment of choice for obstructive sleep apnea (OSA), and studies have shown that there is a correlation between patient adherence and treatment outcomes. Newer CPAP machines can track adherence, hours of use, mask leak, and residual apnea-hypopnea index (AHI). Such data provide a strong platform to examine OSA outcomes in a chronic disease management model. However, there are no standards for capturing CPAP adherence data, scoring flow signals, or measuring mask leak, or for how clinicians should use these data.

METHODS

American Thoracic Society (ATS) committee members were invited, based on their expertise in OSA and CPAP monitoring. Their conclusions were based on both empirical evidence identified by a comprehensive literature review and clinical experience.

RESULTS

CPAP usage can be reliably determined from CPAP tracking systems, but the residual events (apnea/hypopnea) and leak data are not as easy to interpret as CPAP usage and the definitions of these parameters differ among CPAP manufacturers. Nonetheless, ends of the spectrum (very high or low values for residual events or mask leak) appear to be clinically meaningful.

CONCLUSIONS

Providers need to understand how to interpret CPAP adherence tracking data. CPAP tracking systems are able to reliably track CPAP adherence. Nomenclature on the CPAP adherence tracking reports needs to be standardized between manufacturers and AHIFlow should be used to describe residual events. Studies should be performed examining the usefulness of the CPAP tracking systems and how these systems affect OSA outcomes.

Respiratory event detection by a positive airway pressure device

STUDY OBJECTIVES

Compare automatic event detection (AED) of respiratory events using a positive airway pressure (PAP) device with manual scoring of polysomnography (PSG) during PAP treatment of obstructive sleep apnea (OSA).

DESIGN

Prospective PSGs of patients using a PAP device.

SETTING

Six academic and private sleep disorders centers.

PATIENTS

A total of 148 PSGs from 115 participants with OSA (apnea-hypopnea index [AHI] ≥ 15 events/hr) were analyzed.

INTERVENTIONS

A signal generated by the PAP device identifying the AED of respiratory events based on airflow was recorded during PSG.

MEASUREMENTS AND RESULTS

The PSGs were manually scored without visualization of the AED signal and scoring of a hypopnea required a ≥ 4% oxygen desaturation. The apnea index (AI), hypopnea index (HI), and AHI by manual score and PAP AED were compared. A customized computer program compared individual events by manual scoring and AED to determine the true positive, false positive, false negative, or true negative events and found a sensitivity of 0.58 and a specificity of 0.98. The AHI, AI, and HI by the two methods were highly correlated. Bland-Altman analysis showed better agreement for AI than HI. Using a manually scored AHI of ≥ 10 events/hr to denote inadequate treatment, an AED AHI ≥ 10 events/hr had a sensitivity of 0.58 and a specificity of 0.94.

CONCLUSIONS

An AHI < 10 events/hr by PAP AED is usually associated with good treatment efficacy. Differences between manually scored and AED events were primarily due to different criteria for hypopnea detection.

Nasal pillows as an alternative interface in patients with obstructive sleep apnoea syndrome initiating continuous positive airway pressure therapy

Side-effects directly due to the nasal mask are common in patients with obstructive sleep apnoea syndrome (OSAS) commencing continuous positive airway pressure (CPAP). Recently, nasal pillows have been designed to overcome these issues. Limited evidence exists of the benefits and effectiveness of these devices. Twenty-one patients (19 male, 49±10years) with the established diagnosis of OSAS [apnoea/hypopnoea index (AHI): 52±22] and who had a successful CPAP titration were commenced on CPAP therapy (10±2cmH2O), and randomized to 4weeks of a nasal pillow (P) and a standard nasal mask (M) in a crossover design. Outcome measures were objective compliance, AHI, quality of life, Epworth Sleepiness Score (ESS) and CPAP side-effects. There was no difference in compliance (M versus P: 5.1±1.9h versus 5.0±1.7h; P=0.701) and AHI (2.6±2.7 versus 3.0±2.9; P=0.509). Quality of life and ESS improved with CPAP, but there was no difference in the extent of improvement between both devices. Usage of nasal pillows resulted in less reported pressure on the face and more subjects found the nasal pillow the more comfortable device. However, there was no clear overall preference for either device at the end of the study (mask=57%, pillow=43%; P=0.513). The applied CPAP pressure did not correlate with compliance, AHI and ESS. Furthermore, no differences in outcome parameters were noted comparing groups with CPAP pressure <10 and ≥10cm H(2) O. Nasal pillows are equally effective in CPAP therapy, but do not generally lead to improved compliance.

Air leak is associated with poor adherence to autoPAP therapy

STUDY OBJECTIVES

To our knowledge, a systematic study of the effect of air leak on adherence to auto-titrating positive airway pressure (autoPAP) therapy has not been reported. We hypothesized that in patients with obstructive sleep apnea (OSA), greater levels of air leak were associated with poor adherence to autoPAP therapy.

DESIGN

Retrospective cohort study

SETTING

Academic Center

PARTICIPANTS

Ninety-six consecutive patients with high probability for OSA.

INTERVENTIONS

N/A.

MEASUREMENTS

Patients with OSA received 1 week of autoPAP therapy following which both adherence data and air leak information was downloaded from the device. Continuous positive airway pressure (CPAP) therapy was issued for a 5-week period with pressure determined by 90th percentile of that delivered during autoPAP therapy. Adequate adherence was defined as average usage > 4 h per night on all nights.

RESULTS

Forty-three patients were adherent to autoPAP therapy (350 ± 67[SD] min/day), whereas 53 patients were not (122 ± 65 min/day; P < 0.0001). Air leak that was adjusted for pressure delivered was greater in non-adherent patients (7.0 ± 3.5 L/min/cm H(2)O) than that in adherent patients (4.9 ± 1.7 L/min/cm H(2)O; P < 0.0001). Greater residual respiratory events (measured as autoPAP-derived hypopnea index) and proportion of time spent at large leak levels were associated with non-adherence. Patients who were adherent to autoPAP therapy received higher average therapeutic pressures from the autoPAP device than non-adherent patients. Multivariate logistic regression revealed that higher levels of air leak were associated with non-adherence to autoPAP therapy (odds ratio 1.43; 95% CI, 1.03, 1.98; P = 0.03). Moreover, adherence to autoPAP therapy was strongly correlated with subsequent adherence to CPAP therapy (R(2) = 0.74; P < 0.0001).

CONCLUSION

Air leak was associated with poor adherence to autoPAP therapy. We speculate that air leak could be a potential target for future studies aimed at enhancing adherence to autoPAP therapy.

Combined oral appliance and positive airway pressure therapy for obstructive sleep apnea: a pilot study

BACKGROUND

The high efficacy of continuous positive airway pressure (CPAP) in treating obstructive sleep apnea (OSA) is limited by poor compliance often related to pressure intolerance. Mandibular advancement devices (MADs) are proven alternative therapy although not universally effective. A combination of nasal CPAP and MAD may provide another option for CPAP-intolerant patients with incomplete response to MAD.

METHODS

Ten patients with residual apnea/hypopnea events on MAD who were intolerant to CPAP were recruited prospectively from the sleep clinic. After a washout period of 1 week off MAD, subjects were asked to use an auto-CPAP unit along with their prescribed MAD for three consecutive nights. Oxygen desaturations were obtained from overnight oximetry. Efficacy of the combination therapy was evaluated by the Epworth Sleepiness Scale and Smartcard data recordings.

RESULTS

The combination of MAD and nasal CPAP was well tolerated by all participants. Compared to CPAP alone, the optimal CPAP pressure required to eliminate all obstructive events on the combination therapy was reduced from 9.4 ± 2.3 to 7.3 ± 1.4 cm H₂O (p = 0.001). The residual apnea hypopnea index on the MAD decreased from 11.2 ± 3.9 to 3.4 ± 1.5 on the combination therapy (p < 0.001). The number of oxygen desaturations was also less with the combination therapy than with MAD (p < 0.001). Both the MAD and the combination therapy were effective in reducing daytime sleepiness from 12.7 ± 2.1 at baseline to 9.7 ± 3.1 (p = 0.04) and 7.5 ± 4.1 (p = 0.007), respectively.

CONCLUSIONS

Combination therapy of MAD and nasal CPAP is effective in normalizing respiratory disturbances of sleep apnea in selected OSA patients who are intolerant to CPAP.

APAP impact on metabolic syndrome in obstructive sleep apnea patients

PURPOSE

Prevalence of metabolic syndrome (MS) in obstructive sleep apnea (OSA) patients is high. The effect of autoadjusting positive airway pressure (APAP) on MS remains unclear. This study aimed to determine the prevalence of MS in OSA patients before and 6 months after APAP, and to identify potential determinants of metabolic status change.

METHODS

Seventy-four male patients with moderate to severe OSA were enrolled. MS diagnosis was established according to the National Cholesterol Education Program/Adult Treatment Panel III. APAP was prescribed to all patients.

RESULTS

In the studied population, mean age was 55.9 years (SD 10.7 years), median body mass index (BMI), Epworth sleepiness scale (ESS), and respiratory disturbance index (RDI) were 33.4 kg/m(2) (interquartile range (IQR) 8.4 kg/m(2)), 12.0 (IQR 8.0), and 46.9/h (IQR 33.6/h), respectively. Prevalence of MS before and 6 months after APAP was 63.5% and 47.3%, respectively, and this difference was statistically significant (p = 0.004). In the subgroup of patients with MS at baseline (n = 47), 14 did not present MS after APAP. In these patients, a significant negative association with RDI (p = 0.016) and a positive association with percent of total days of usage (p = 0.014) were found. Blood pressure (p = 0.018) and serum triglycerides (p = 0.001) had a statistically significant reduction during this period. In patients that still had MS, 22.2% presented a reduction of the number of MS criteria.

CONCLUSIONS

After 6 months, APAP reduced the prevalence of MS, mainly in patients with less severe OSA and with a better therapeutic compliance. Blood pressure and serum triglycerides reduction contributed to this metabolic status change.