auto-CPAP Device Research Articles

The Automatic Algorithm of the Auto-CPAP Device as a Tool for the Assessment of the Treatment Efficacy of CPAP in Patients with Moderate and Severe Obstructive Sleep Apnea Syndrome.

Obstructive sleep apnea syndrome (OSAS) is a common sleep-related breathing disorder where precise treatment assessment is of high importance. We aimed to validate an automatic algorithm of the auto-CPAP device and reveal polygraph usefulness in the OSAS diagnosis and treatment of outpatients. One hundred patients with moderate OSAS, severe OSAS, and excessive daytime sleepiness qualified for CPAP treatment were included. The study was conducted in three stages. The first stage included a minimum 6-hour polysomnographic examination to select moderate and severe OSAS. The second stage involved an auto-CPAP treatment lasting at least 4 h with simultaneous polygraph recording. The third stage was a titration of at least 4 h with auto-CPAP. The Apnea–Hypopnea Index (AHI) and oxygen desaturation index (ODI) were calculated under auto-CPAP treatment, simultaneously using polygraph (stage two), and as a result of treatment with auto-CPAP (stage three). The mean AHI was 40.0 ± 20.9 for OSAS. Auto-CPAP treatment was effective in 97.5%. The mean residual AHI was 8.6 ± 4.8; there was no significant difference between the AHI CPAP, and the AHI polygraph values were assessed with an accuracy of 3.94/h. The sensitivity and specificity of calculated cut point 8.2 event/hour were: 55% and 82%, respectively. The calculated AUC for the AHI CPAP parameter was 0.633. Presented data confirmed that the automatic algorithm of auto-CPAP is a good tool for the assessment of the treatment efficacy of CPAP in patients, i.e., home setting, with a moderate or severe stage OSAS-presented high sleepiness.

Alteration of Auto-CPAP requirements in obstructive sleep apnea patients with COVID-19 history

BackgroundCoronavirus disease 2019 (COVID-19) is an infectious disease that leads to critical respiratory problems.Obstructive sleep apnea (OSA) is the most common sleep-associated breathing disease and is represented by repetitive experiences of constraint of the respiratory tract prompting to reduced or deficient breathing during sleep.Auto-Continuous positive airway pressure (Auto-CPAP) is a modality of respiratory ventilation used as gold standart in the treatment of OSA. ObjectiveThis study was performed to conclude the alteration of Auto-CPAP levels in OSA patients who had COVID-19 history. MethodsNineteen OSA patients who had cured COVID-19 and used Auto-CPAP were included in this study. Nightly Auto-CPAP 95th percentile pressure (95thpp), median CPAP pressure and AHI before COVID-19 disease and one month after COVID therapy were recorded from electronic cards of Auto-CPAP devices. ResultsBefore COVID infection, average Auto-CPAP 95thpp was 8.56 ± 0.17 cm H2O. One month after COVID-19, average Auto-CPAP 95thpp was 9.78 ± 0.21 cm H2O (P < 0.01). While Median CPAP pressure was 7.49 ± 0.16 cm H2O before COVID, it was found to be 8.15 ± 0.19 cm H2O after the disease (P < 0.01). ConclusionsThe increase in need of average Auto-CPAP 95thpp and median CPAP pressure in OSA patients who have had COVID-19 disease and use Auto-CPAP shows that this disease causes problems in both the lower and upper airways.

Respiratory failure: technical means for diagnosis and respiratory support

The necessity of early diagnosis of respiratory diseases, especially in the context of the COVID-19 pandemic, by means of pulse oximetric screening and monitoring has been substantiated. The expediency of using portable pulse oximeters by therapists and general practitioners has been shown. The main respiratory diseases accompanied by respiratory failure, which can be detected in time by pulse oximetry, are the chronic obstructive pulmonary disease and the obstructive sleep apnea-hypopnea syndrome. Early detection of these diseases is an important task because of the mild symptoms of these diseases in the early stages, and as a result, the prevalence of late diagnosis. Special attention is given to the pulse oximetry for COVID-19 detection, as this infection is also accompanied by respiratory failure. The use of oxygen concentrators and auto CPAP devices for the treatment of respiratory failure as well as rehabilitation has been argued. The effectiveness of the appointment of long-term oxygen therapy using oxygen concentrators for patients with chronic obstructive pulmonary disease, CPAP therapy using automatic CPAP devices for patients with obstructive sleep apnea-hypopnea syndrome with mandatory pulse oximetry monitoring has been confirmed. The analysis of 120 cases of treatment of moderate and severe COVID-19 cases complicated by the pneumonia has been carried out. The efficiency of the use of oxygen concentrators for supplying oxygen to patients at a flow rate not more than 5 l/min has been proven. It has been found that no more than 10 % of patients needed an oxygen flow rate more than 5 l/min. At the same time, the possibility of using CPAP devices for non-invasive ventilation of lungs using full-face masks has been shown. The expediency of using oxygen concentrators and CPAP devices for the rehabilitation of patients after COVID-19 has been noted.

Effectiveness of a lightweight portable auto-CPAP device for the treatment of sleep apnea during high altitude stages of the Dakar Rally: a case report

Sleep-related breathing disturbances are exacerbated at altitude in patients with Obstructive Sleep Apnea (OSA). The objective of this case report was to determine if a portable auto-CPAP device effectively treated sleep apnea across different altitudes. We report the severity of sleep apnea from 60 to 12,000 feet high in a man with severe OSA (Apnea Hypopnea Index at diagnosis = 60 events/hour) during the 2017 Dakar rally over the Andes mountains. The man was equipped with a lightweight portable auto-CPAP device with a narrow window [6-8 cmH2O]. Pressures delivered and corresponding residual events were assessed at different altitudes. The 95th percentile pressure reached the maximal set pressure at the highest altitudes, and residual AHI increased from 5 events/hour to 45 events/hour at the highest altitudes. Potential mechanisms behind the development of central apnea, and optimal clinical management at altitude are discussed in the light of the findings.

Abstract TMP88: High Accuracy of Auto-CPAP for Obstructive Sleep Apnea in Acute Stroke Patients

Background: Obstructive sleep apnea (OSA) is very common in acute stroke patients and has been associated with a poor short-term and long-term outcome. Polysomnography (PSG) is the gold standard diagnostic method for OSA, but it is not feasible as a routine for all acute stroke patients. Therefore, it is essential to validade alternative methods to accurately diagnose OSA in acute stroke patients. The newest generation of automatic continuous positive airway pressure (auto-CPAP) devices innovates by the possibility of detecting the different types of respiratory events. However, the accuracy of auto-CPAP devices for OSA diagnosis has never been tested in comparison to PSG in the acute stroke setting. The main objective of this study was to evaluate the accuracy of an auto-CPAP device to diagnose OSA and to validate its algorithm of respiratory events detection to diagnose OSA in patients during the acute phase of stroke. Methods: A sleep study was performed with PSG and auto-CPAP device, simultaneously, within the first 48 hours after the acute stroke onset. The Receiver Operating Characteristic Curve (ROC), C-statistics, Spearman correlation coefficient, and intraclass correlation coefficient were analyzed. Results: We prospectively evaluated 31 adult patients with acute stroke. The mean age was 59.7 ± 12 years and 60% were males. All patients used auto-CPAP for longer than 4 hours. The PSG revealed an apnea-hypopnea index (AHI) mean of 34 ± 41 events/h, and the auto-CPAP showed an AHI of 18 ± 16 events/h. The area under the ROC curve for OSA diagnosis by the auto-CPAP was above 0.90, with sensitivity and specificity above 80% for each AHI value. The Spearman correlation coefficients (rs) of the AHI, of the hypopnea index, of the obstructive apnea index and of the central apnea index were 0.92; 0.89; 0.63 and 0.62, respectively. The intraclass correlation coefficients between device-detected and PSG manually scored events were 0.60 for AHI, 0.64 for hypopnea index, and 0.45 for apnea index. Conclusion: The auto-CPAP showed an excellent accuracy for the diagnosis of OSA and it was well tolerated by acute stroke patients. Our results suggest that auto-CPAP should be considered as the preferred diagnostic tool for OSA diagnosis during the acute phase of stroke.

Oral appliance treatment outcome can be predicted by continuous positive airway pressure in moderate to severe obstructive sleep apnea

BackgroundStudies show that the therapeutic CPAP pressure is associated with oral appliance (OA) treatment outcome in obstructive sleep apnea (OSA) patients. However, these studies included either CPAP adherent patients using fixed pressure devices, or partly CPAP non-adherent patients using fixed pressure or auto-adjusting (auto-CPAP) devices. In many countries, auto-CPAP is predominately used, and only those non-adherent to therapy need a change to OA. Therefore, studies examining the relationship between CPAP pressures and OA treatment outcome should focus on patients non-adherent to auto-CPAP.PurposeThe purpose of this paper is to assess if CPAP pressures predicted OA treatment outcome in patients non-adherent to auto-CPAP therapy.MethodsThe OA treatment responders and non-responders were defined by two success criteria ((1) AHI < 5; (2) 5 ≤ AHI < 10 and > 50% AHI reduction). Logistic regression analyses were performed for CPAP pressures and baseline variables. ROC curve analyses were used to identify CPAP pressure cutoff values, alone and combined with other explanatory variables, predicting the OA treatment outcome.ResultsEighty-seven patients with moderate or severe OSA were included. Maximum CPAP pressures (CPAPmax) were higher in non-responders by both criteria and were, together with baseline AHI, associated with the OA treatment outcome in multivariate regression analyses. ROC curves identified an optimal CPAPmax cutoff of 12 cm H2O, corresponding to a positive predictive value (PPV) of 0.85 in predicting non-response using criterion 1. A prediction model combining CPAPmax > 12 and baseline AHI ≥ 30 had a PPV of 1.0 for non-response by both criteria.ConclusionsMaximum CPAP pressure was a moderate predictor of OA treatment outcome, but combined with baseline AHI, the ability to identify OA non-responders was high.

Optimal level of continuous positive airway pressure: Auto-CPAP titration versus predictive formulas

Continuous positive airway pressure (CPAP) is the most effective treatment of obstructive sleep apnea hypopnea syndrome (OSAHS). The therapeutic level of CPAP is achieved by manual titration or an auto CPAP device, but an alternative way involves the use of mathematical equations.Aim of the work: to compare between CPAP pressure obtained by autoCPAP titration and that calculated from five different mathematical formulas. MethodsWe enrolled 30 patients with OSAHS. In addition to standard examination, anthropometric measurements and investigations, all patients underwent an over-night polysomnography (PSG) AutoCPAP (level II) to diagnose OSAHS. Manual scoring of polysomnographic data was performed according to criteria established by the American Academy of Sleep Medicine in 2012. All patients used AutoCPAP with pressure ranging from 4 to 20cm H2O. Information recorded was downloaded and the following data were retrieved: 1) P90% (90th percentile pressure delivered by the autoCPAP device and eliminated snoring, flow limitation and apnea), this pressure was chosen as the therapeutic pressure, 2) peak pressure level, 3) mean pressure level, 4) the estimated residual apnea hypopnea index (AHI), 5) P90%/mean pressure level ratio, which is an index of pressure variability, was calculated. Five predictive formulas were retrieved from published literature and calculated for all patients. ResultsThe mean±SD of AHI was 47.94±27.21events/h. OSAHS was mild in 5 patients (16.67%), moderate in seven patients (23.33%), and severe in 18 patients (60%). AutoCPAP P90% was 10.59±2.66cm H2O and showed significantly direct correlation with each of Epworth sleepiness scale (p=0.000), BMI (p=0.001), neck circumference (p=0.002), neck to height ratio (p=0.000), and AHI (p=0.000). Also it was found to show statistically significant inverse correlation with each of minimal (p=0.000), and average minimal oxygen saturation (p=0.032). The pressure calculated by Hoffstein et al. equation was significantly lower than autoCPAP P90%. There was no significant difference with pressure calculated by the other four formulas and P90%. The following model of predictive equation was derived from the studied sample: Predicted therapeutic pressure=4.740+68.575 X (N/H) – 0.153 X (Minimal SpO2). ConclusionsPredictive formulas might be useful as an alternative to autoCPAP. The model of predictive formula derived from the present small sample of Egyptian patients with OSAHS should be validated on a larger sample size.

Clinical significance of remaining flow limitation during treatment using the Auto-CPAP device programmed algorithms to detect flow limitation

Clinical significance of remaining flow limitation during treatment using the Auto-CPAP device programmed algorithms to detect flow limitation

Essential knowledge of accuracy and setting for the Auto-CPAP device treatment

Essential knowledge of accuracy and setting for the Auto-CPAP device treatment

Obstructive sleep apnoea in the elderly: role of continuous positive airway pressure treatment.

Almost all the information about the effect of continuous positive airway pressure (CPAP) in patients with obstructive sleep apnoea (OSA) comes from clinical trials involving only middle-aged patients. The objective of this study was to assess the effect of CPAP treatment in elderly patients with severe OSA on clinical, quality-of-life and neurocognitive spheres. We performed an open-label, randomised, multicentre clinical trial in a consecutive clinical cohort of 224 elderly (≥70 years old) patients with confirmed severe OSA (apnoea-hypopnea index ≥30) randomised to receive CPAP (n=115) or no CPAP (n=109) for 3 months. A sleep study was performed by either full polysomnography or respiratory polygraphy. CPAP titration was performed by an autoCPAP device. The primary endpoint was quality of life (Quebec Sleep Questionnaire) and secondary endpoints included sleep-related symptoms, presence of anxiety/depression, office-based blood pressure and some neurocognitive tests. The mean±sd age was 75.5±3.9 years. The CPAP group achieved a greater improvement in all quality-of-life domains (p<0.001; effect size: 0.41-0.98), sleep-related symptoms (p<0.001; effect size 0.31-0.91) as well as anxiety (p=0.016; effect size 0.51) and depression (p<0.001; effect size: 0.28) indexes and some neurocognitive tests (digit symbol test (p=0.047; effect size: 0.20) and Trail Making Test A (p=0.029; effect size: 0.44)) in an intention-to-treat analysis. In conclusion, CPAP treatment resulted in an improvement in quality of life, sleep-related symptoms, anxiety and depression indexes and some neurocognitive aspects in elderly people with severe OSA.

Changing the Direction of Sleep Medicine: Business can Boom, but it is Not as Usual

Changing the Direction of Sleep Medicine: Business can Boom, but it is Not as Usual

The accuracy of autotitrating CPAP-determined residual apnea–hypopnea index

Autotitrating continuous positive airway pressure (auto-CPAP) devices not only titrate CPAP pressures but also measure residual respiratory events. The aim of the present study was to determine the accuracy of auto-CPAP-derived residual apnea-hypopnea index (AHI). We studied 137 consecutive patients (72.3% men) with obstructive sleep apnea from January 2008 to December 2010 who underwent in-laboratory overnight polysomnography (PSG) using auto-CPAP. We excluded patients with comorbidities like congestive heart disease, chronic obstructive pulmonary disease, or hypoventilation syndromes and patients with central sleep apnea. Residual AHI obtained from the auto-CPAP device by smart card (CPAP-AHI) was compared simultaneously with AHI from an overnight PSG on auto-CPAP (PSG-AHI) using Bland-Altman analysis and Wilcoxon signed-rank test. The mean AHI on the diagnostic study was 45.08 ± 1.8. During the titration, auto-CPAP markedly suppressed the respiratory events (PSG-AHI, 3.40 ± 0.20). On the other hand, CPAP-AHI was 3.35 ± 0.17. Bland-Altman analysis showed good agreement between auto-CPAP-AHI and PSG-AHI (AHI mean difference of 0.05, and the limits of agreement for the AHI were from +4.9 to -4.8). Two methods have also been compared with paired samples t test and no statistically significant difference was found (p > 0.05). Auto-CPAP can identify residual respiratory events equivalent to the use of PSG in a selected population.

Obstructive pressure peak: a new method for differentiation of obstructive and central apneas under auto-CPAP therapy

Auto-CPAP devices (APAP) are controlled, e.g.,by the respiratory flow and pressure to adjust the treatment pressure to the variable obstruction in sleep apnea syndromes.By obstruction of the upper airway during inspiration,a pressure difference between the lower airways and the mask can be measured. In case of an opening of the pharynx at the end of the obstruction, the pressure decreases immediately. This brief negative pressure, the so-called obstructive pressure peak (OPP) can be used to identify obstruction or open airways with the algorithm of an APAP device. Useless pressure increases, e.g., after central apneas without obstruction may be avoided. We therefore investigated the association of the OPP signal with respiratory events during APAP therapy. In this pilot study, 13 patients with obstructive sleep apnea syndrome were evaluated. Attended automatic CPAP titration (SOMNO balance, Fa Weinmann Hamburg/Germany)was performed. The OPP signal was recorded synchronous lyin parallel with the polysomnographic data. If the OPP signal was within a time range of ± 5 s of the resumption of normal breathing, it was assigned to the event. A total of 480 sleep-related breathing disorders events were studied. The most common were the mixed apneas associated with more than 90% of all cases with an OPP signal, followed by obstructive sleep apneas (66.7%)and central apneas (38%). The difference in OPP frequency distribution between central apneas and obstructive apneas was significant with p<0.001. The analysis of the pressure characteristics of APAP treatment with the registration of OPP allows a further differentiation in obstructed and not obstructed upper airways.

Residual sleep-disordered breathing during autotitrating continuous positive airway pressure therapy

Obstructive sleep apnoea (OSA) is often treated with autotitrating continuous positive airway pressure (autoCPAP) devices. Clinical and bench tests of these devices have suggested performance limitations. These studies do not indicate whether this is a failure to detect or a failure to respond to airway obstruction. In this randomised, crossover trial, 34 patients with moderate-to-severe OSA underwent polysomnography on two laboratory visits. The autoCPAP device was randomly set to a fixed subtherapeutic pressure (detection assessment) or autotitrating mode (response assessment). Airflow was measured both from the autoCPAP (autoCPAP flow) and directly from the nasal mask, and recorded on polysomnography. Apnoea/hypopnoea indices (AHIs) measured at the two sites and from the autoCPAP download report were compared. Regarding detection, the AHI measured from the nasal mask showed good agreement with the autoCPAP flow AHI, but agreement was lower with the autoCPAP report AHI. In autotitrating mode, there was significant misclassification of those with and without OSA (AHI ≥ 10 events · h(-1)) on the autoCPAP report. Regarding response, residual OSA (AHI ≥ 10 events · h(-1)) was still evident in 24% of patients during autotitration. In some patients, autoCPAP fails to detect and/or respond to sleep apnoea. Clinicians should consider limitations of each device and use caution when using autoCPAP report statistics to verify effective treatment.

A Randomized Crossover Trial of the Effect of a Novel Method of Pressure Control (SensAwake) in Automatic Continuous Positive Airway Pressure Therapy to Treat Sleep Disordered Breathing

To study the acute effect of the new SensAwake CPAP modality (reducing pressure on awakenings) on wake after sleep onset (WASO) and other polysomnographic measures in patients with obstructive sleep apnea (OSA). Randomized crossover trial comparing an automatic continuous positive airway pressure device (AutoCPAP) with and without SensAwake on sleep architecture. CPAP naive patients received each therapy for a single night in the laboratory with at least 1-week washout. Both patients' and technicians' subjective satisfaction was assessed. Pressure data measured and stored by the AutoCPAP device were also analyzed. OSA was controlled adequately by both modes (SensAwake ON apnea hypopnea index ± SD, AHI = 5.3 ± 5.6/h vs. SensAwake OFF = 5.4 ± 5.8, p = 0.9) in the 42 patients who completed the protocol. Mean and 90% pressures were significantly lower with SensAwake (mean ON = 6.9 ± 1.9 vs. OFF = 7.7 ± 2.5 cm H(2)O, p < 0.05; 90% pressure ON = 9.6 ± 2.7 vs. OFF = 10.6 ± 2.7 cm H(2)O, p < 0.02). SensAwake did not improve WASO (ON = 74 ± 54 min vs. OFF = 78 ± 51 min, p = 0.6). There were no differences in other sleep architecture measures or patient satisfaction between the 2 modalities. AutoCPAP-measured AHI closely approximated PSG-derived (ROC AUC = 0.81 [95% CI 0.71-0.92], p = 0.0001). SensAwake provides similar control of the AHI to the standard AutoCPAP mode but does so at lower mean and 90% pressures. However, no measure of sleep architecture was significantly improved by the SensAwake mode during this initial acute exposure. The internal AutoCPAP AHI detection and calculation was similar to PSG-derived AHI measures. Longer term studies are needed to evaluate any long-term influence of SensAwake on WASO.

Response of automatic continuous positive airway pressure devices in a normal subject

To the Editors: Obstructive sleep apnoea (OSA) is a prevalent disease whereby people become unable to breathe when asleep. During sleep the pharyngeal walls are sucked in and collapse completely, causing full (termed apnoea) or incomplete (termed hypopnoea) abolition of airflow. OSA can lead to daytime fatigue and sleepiness, impairment in cognitive functions, motor vehicle crashes, hypertension, cardiovascular disease, stroke and premature deaths [1]. OSA is easily treated with continuous positive pressure applied throughout sleep [2]. The right amount of pressure is determined individually during a titration night, when pressure is gradually increased to keep the airway open to allow for normal sleep and breathing [2]. In 1993 it was postulated that this process of titration could be performed with a stand alone blower equipped with a microprocessor guiding the positive pressure [3]. The idea was to use the blower as a monitoring device identifying abnormal breathing events and react by increasing pressure until disappearance of the abnormal events. The device would then slowly decrease pressure until events reappeared and the pressure would then be increased again [3]. These machines, termed automatic continuous positive airway pressure devices (autoCPAP), were proposed as monitoring or even diagnostic machines [4], as devices used for one night to determine the fixed CPAP level to be used thereafter [5] or even as therapeutic machines to be used every night and to adapt the pressure necessary to keep the pharynx open at all times [6]. When autoCPAP devices were tested in a bench study it was shown that no two devices reacted alike, that many devices did not even recognise the events they were supposed to act upon and that even when recognising the events, many were not able to …

Evaluation of the Apnea-Hypopnea Index Determined by the S8 Auto-CPAP, a Continuous Positive Airway Pressure Device, in Patients with Obstructive Sleep Apnea-Hypopnea Syndrome

Continuous positive airway pressure (CPAP) has been established as an effective treatment for obstructive sleep apnea-hypopnea syndrome (OSAHS). Recently, several auto-CPAP devices that can detect upper airway obstructive events and provide information about residual events while patients are on CPAP have come into clinical use. The purpose of this study was to compare the apnea-hypopnea index (AHI) determined by the S8 auto-CPAP device with the AHI derived by polysomnography in patients with OSAHS. Consecutive patients with OSAHS titrated on S8 auto-CPAP were included. The correlation between AHI determined by manual scoring (AHI-PSG) and by S8 (AHIS8) during an overnight in-hospital polysomnogram with the patient on CPAP was assessed. Furthermore, the apnea index (Al) and the hypopnea index (HI) were evaluated separately. Seventy patients with OSAHS (94% men) were enrolled. The mean AHI on the diagnostic study was 51.9 +/- 2.4. During the titration, this device markedly suppressed the respiratory events (AHI-PSG, 4.2 +/- 0.4; AI, 1.9 +/- 0.3; HI, 2.3 +/- 0.3). On the other hand, the AHI-S8 was 9.9 +/- 0.6 (AI-S8, 2.4 +/- 0.3; HI-S8, 7.5 +/- 0.4). There was a strong correlation between the overall AHI-PSG and the AHI-S8 (r = 0.85, p < 0.001), with a stronger correlation in the apnea component AI-PSG and the AI-S8 (r = 0.93, p < 0.001), whereas there was a weaker correlation between the HI-PSG and the HI-S8 (r = 0.67, p <0.001). Using the same airflow signals as those of the CPAP device, a strong correlation between the AHI-PSG and the AHI-S8 was observed. However, the correlation was weakened when the analysis was limited to the HI.

Regulationsverhalten von Auto-CPAP-Geräten während der Simulation von schlafbezogenen Atemflussmustern

The function of automatic CPAP devices is difficult to investigate using clinical examinations due to the high variability of breathing disorders. With a flow generator, however, identical breathing patterns can be reproduced so that comparative studies on the behaviour of pressure of APAP devices are possible. Because the algorithms of APAP devices based on the experience of users can be modified without much effort, also previously investigated devices should regularly be reviewed with regard to programme changes. Had changes occurred in the algorithms of 3 selected devices--compared to the previously published benchmark studies? Do the current versions of these investigated devices differentiate between open and closed apnoeas? With a self-developed respiratory pump, sleep-related breathing patterns and, with the help of a computerised valve, resistances of the upper respiratory tract were simulated. Three different auto-CPAP devices were subjected to a bench test with and without feedback (open/closed loop). Open loop: the 3 devices showed marked differences in the rate of pressure rise but did not differ from the earlier published results. From an initial pressure of 4 mbar the pressure increased to 10 mbar after a different number of apnoeas (1-6 repetitive apnoeas). Only one device differentiated between closed and open apnoeas. Closed loop: due to the pressure increase, the flow generator simulated reduced obstruction of the upper airways (apnoeas changed to hypopnoeas, hypopnoeas changed to flattening) but different patterns of pressure regulation could still be observed. By applying bench-testing, the algorithms of auto-CPAP devices can regularly be reviewed to detect changes in the software. The differentiation between open and closed apnoeas should be improved in several APAP devices.

Bench study of auto-CPAP devices using a collapsible upper airway model with upstream resistance

The aim of this study was to investigate the response of auto-CPAP devices to respiratory events (apnea, hypopnea, flow-limitation and snoring) on the same condition using a physiological upper airway model. The hypothesis of this study is that collapsibility of the flow-limiting collapsible segment of the airway is influenced by the upstream airway resistance. Five auto-CPAP devices, AutoSet T, AutoSet Spirit, Goodnight 420E, PV10i and REMstar Auto were evaluated. Apnea: all the devices increased the auto-CPAP level, while AutoSet T and AutoSet Spirit did not respond to apnea for 30s. Hypopnea: all the devices except the AutoSet T and Goodnight 420E increased pressure. Flow-limitation: all the devices except the PV10i and REMstar Auto increased pressure. Snoring: the snoring sounds disappeared when REMstar Auto and PV10i were used, and the Goodnight 420E lowered the level of snoring. In conclusion, the response of auto-CPAP devices to respiratory events differed. Collapsible upper airway model with upstream resistance is useful for the first-step assessment of auto-CPAP devices.

Evaluation of autoCPAP devices in home treatment of sleep apnea/hypopnea syndrome

Background and purpose Quality of life (QOL) and sleepiness for patients with sleep apnea/hypopnea syndrome (SAHS) might improve with continuous positive airway pressure devices working in auto-adjust mode (autoCPAP) by allowing pressure modulations following patient needs. Clinical comparisons between devices driven by different algorithms are needed. Methods We compared the clinical effectiveness of fixed pressure CPAP and four different autoCPAP devices by assessing compliance and QOL (36-item short-form health survey [SF-36]). SAHS patients were randomly allocated to five groups. Polysomnography (PSG) was performed to titrate the effective pressure in the constant CPAP group and evaluate residual apnea/hypopnea index (AHI) under autoCPAP. Follow-up consisted of clinical visits at three and six months by homecare technicians who assessed compliance, symptom scores and SF-36 scores. A laboratory-based PSG using the same CPAP/autoCPAP device as at home was performed at six months. Results Eighty-three patients (mean age 56 ± 10 yrs) with mean body mass index (BMI) 30.8 ± 5.3 kg/m 2 and severe SAHS (mean AHI: 52.3 ± 17.8/h) were included. There were no differences in clinical symptoms or QOL scores, and similar clinical and PSG improvements were seen in all groups. CPAP use was >5 h per night, without any significant difference between groups. Conclusions AutoCPAP is equally as effective as fixed CPAP for long-term home treatment in severe SAHS patients.