Automatic CPAP Devices Research Articles

Early Diagnosis of Respiratory Disease in Light of COVID-19 Infection and Use of Oxygen Concentrators and CPAP Devices for the Treatment of Respiratory Failure

The need for early diagnosis of respiratory diseases, especially in the context of the COVID-19 coronavirus infection pandemic, by means of pulse oximetry screening and monitoring has been substantiated. The expediency of using portable pulse oximeters by therapists and general practitioners is shown. The main respiratory diseases accompanied by respiratory failure, which can be promptly detected by pulse oximetry, are chronic obstructive pulmonary disease and obstructive sleep apnea-hypopnea syndrome. Early detection of these diseases is an urgent task due to the low severity of symptoms of these diseases in the early stages and, as a consequence, the prevalence of late diagnosis. Pulse oximetry to detect coronavirus infection COVID-19 deserves special attention, since this infection is also accompanied by respiratory failure. The use of oxygen concentrators and CPAP devices for the treatment of respiratory failure has been argued. The effectiveness of the appointment of long-term oxygen therapy using oxygen concentrators in patients with chronic obstructive pulmonary disease, CPAP therapy using automatic CPAP devices in patients with obstructive sleep apnea-hypopnea syndrome with mandatory pulse oximetry monitoring has been confirmed. A retrospective analysis of 120 cases of treatment of moderate and severe COVID-19 infection complicated by the development of pneumonia was carried out. The efficiency of using oxygen concentrators to supply patients with oxygen at a flow rate of up to 5 l / min has been proven. It was found that no more than 10% of patients needed an oxygen flow at a rate of more than 5 l/min. At the same time, the possibility of using CPAP devices for non-invasive ventilation of the lungs using full-face masks has been shown. The expediency of using oxygen concentrators and CPAP devices for the rehabilitation of patients who have undergone COVID-19 was noted.

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.

Extended evaluation of the efficacy of a proactive forced oscillation technique-based auto-CPAP algorithm.

Previous studies revealed substantially varying therapy efficacy of automatic continuous positive airway pressure (APAP) devices in the treatment of obstructive sleep apnea (OSA). We evaluated the efficacy of a new APAP device using the forced oscillation technique (FOT) to evaluate upper airway obstruction during apneas and flow contour analyses during hypopneas. Forty-six initially diagnosed OSA patients were included and the pressure range was set from 5 to 20hPa. Therapy efficacy was assessed based on the reduction of apnea-hypopnea index (AHI), improvement of objective sleep quality parameters, and the appropriateness of the device's pressure regulation. AHI and arousal index significantly decreased during APAP therapy (median [interquartile range]: AHI 36 [23-55] vs. 2 [1-6]/h, arousal index 30 [22-45] vs. 15 [10-19]/h, both p < 0.001). The amount of slow wave sleep (SWS) and rapid-eye-movement (REM) sleep significantly increased (SWS 20 [14-29] vs. 29 [19-34]%, REM 16 [11-21] vs. 24 [14-30]%, both p < 0.01). Most residual respiratory events during therapy were of central etiology and attributable to five patients, who presented with treatment-emergent central sleep apnea. The device's pressure regulation abolished most obstructive respiratory events (n = 6.7 residual obstructive events per patient). Of central respiratory events, 534/646 (83%) did not lead to pressure increases. This pilot study provides a proof of concept that the APAP device combining FOT and evaluation of flow contour allows for the suppression of obstructive events without relevant false reactions.

Impact of CPAP therapy on erectile function during sleep and testosterone level in men with sleep apnea syndrome

The article presents the results of a polysomnographic study with simultaneous monitoring spontaneous nocturnal erections - Nocturnal Penile Tumescences (NPT) in 69 men with age-related androgen deficiency (AAD). Of these, 45 patients were diagnosed with obstructive sleep apnea syndrome (OSAS). In 34 of the 45 patients with OSAS, regimens of non-invasive ventilation with positive-positive airway pressure (CPAP) were selected. Titration was carried out using automatic CPAP-devices for 2 months. The control group (n=24) comprised men with AAD, matched by the "copy-pair" type without clinical manifestations of respiratory disturbances during sleep. Extreme fragmentation of sleep with a significant predominance of the 1st and 2nd stages of the slow sleep phase, the deficiency of deep sleep stages and the significant shortening of the fast sleep phase was leveled by using a constant positive pressure in the upper respiratory tract. CPAP-therapy produced the phenomenon of a "rebound" of slow-wave sleep and fast-sleep phase. Before treatment, men with OSAS had a disruptive pattern of NPT (quantitative and qualitative characteristics). CPAP-therapy resulted in its recovery and maximum preservation relative to fast sleep phase time boundaries. However, the trend towards increasing testosterone levels was not significant, which requires additional testosterone replacement therapy concurrently with CPAP therapy in patients with OSAS and AAD.

Effect of APAP and heated humidification with a heated breathing tube on adherence, quality of life, and nasopharyngeal complaints.

Positive airway pressure (PAP) therapy adherence can be affected by rhinitis sicca and xerostomia complaints. Additional heated humidification (HH) is the appropriate method when such complaints arise. The aim of this study was to determine if HH with a supplementary heated breathing tube can increase adherence, reduce subjective nasopharyngeal complaints (NPC), and improve sleepiness (ESS: Epworth Sleepiness Scale) and quality of life (FOSQ: Functional Outcome of Sleep Questionnaire). We subdivided 72 obstructive sleep apnea (OSA) patients into two groups before therapy initiation. The NPC risk group consists of subjects with NPC and the low-risk group without. The risk group was identified by a score of >9 in a 5-item 25-point NPC questionnaire and pathological ESS. All patients were eligible for automatic CPAP devices (APAP), which were randomly configured with or without HH during 6 weeks. The adherence differences with and without HH were not significant in the NPC risk group (330 ± 103 vs. 281 ± 118 min/night) and in the low-risk group (330 ± 116 vs. 321 ± 89). NPC and ESS scores in the risk group were both significantly reduced with HH. Daily function (FOSQ) in the risk group was significantly improved with HH (90.0 ± 11.9 vs. 82.0 ± 12.0 (p < 0.05)). HH showed a tendency to improve APAP adherence. The adherence in both groups was quite high, and for that reason, it is difficult to show a statistically significant effect. A differentiation into NPC risk groups before starting PAP treatment is useful. HH reduces side effects and sleepiness and improves quality of life in an NPC risk group.

Comparative assessment of several automatic CPAP devices' responses: a bench test study.

Automatic continuous positive airway pressure (APAP) devices adjust the delivered pressure based on the breathing patterns of the patient and, accordingly, they may be more suitable for patients who have a variety of pressure demands during sleep based on factors such as body posture, sleep stage or variability between nights. Devices from different manufacturers incorporate distinct algorithms and may therefore respond differently when subjected to the same disturbed breathing pattern. Our objective was to assess the response of several currently available APAP devices in a bench test.A computer-controlled model mimicking the breathing pattern of a patient with obstructive sleep apnoea (OSA) was connected to different APAP devices for 2-h tests during which flow and pressure readings were recorded. Devices tested were AirSense 10 (ResMed), Dreamstar (Sefam), Icon (Fisher & Paykel), Resmart (BMC), Somnobalance (Weinmann), System One (Respironics) and XT-Auto (Apex). Each device was tested twice.The response of each device was considerably different. Whereas some devices were able to normalise breathing, in some cases exceeding the required pressure, other devices did not eliminate disturbed breathing events (mainly prolonged flow limitation). Mean and maximum pressures ranged 7.3–14.6 cmH2O and 10.4–17.9 cmH2O, respectively, and the time to reach maximum pressure varied from 4.4 to 96.0 min.Each APAP device uses a proprietary algorithm and, therefore, the response to a bench simulation of OSA varied significantly. This must be taken into account for nasal pressure treatment of OSA patients and when comparing results from clinical trials.

Comparison of manual versus automatic continuous positive airway pressure titration and the development of a predictive equation for therapeutic continuous positive airway pressure in Chinese patients with obstructive sleep apnoea

Whether the therapeutic nasal continuous positive airway pressure (CPAP) derived from manual titration is the same as derived from automatic titration is controversial. The purpose of this study was to compare the therapeutic pressure derived from manual titration with automatic titration. Fifty-one patients with obstructive sleep apnoea (OSA) (mean apnoea/hypopnoea index (AHI) = 50.6 ± 18.6 events/h) who were newly diagnosed after an overnight full polysomnography and who were willing to accept CPAP as a long-term treatment were recruited for the study. Manual titration during full polysomnography monitoring and unattended automatic titration with an automatic CPAP device (REMstar Auto) were performed. A separate cohort study of one hundred patients with OSA (AHI = 54.3 ± 18.9 events/h) was also performed by observing the efficacy of CPAP derived from manual titration. The treatment pressure derived from automatic titration (9.8 ± 2.2 cmH(2)O) was significantly higher than that derived from manual titration (7.3 ± 1.5 cmH(2)O; P < 0.001) in 51 patients. The cohort study of 100 patients showed that AHI was satisfactorily decreased after CPAP treatment using a pressure derived from manual titration (54.3 ± 18.9 events/h before treatment and 3.3 ± 1.7 events/h after treatment; P < 0.001). The results suggest that automatic titration pressure derived from REMstar Auto is usually higher than the pressure derived from manual titration.

Technik und Aussagemöglichkeiten von Atmungsmodellen

In recent years, several comparisons of ventilators for invasive and noninvasive mechanical ventilation or automatic continuous pressure therapy (APAP) were published. Simulations were used with different test sequences. Simulations are particularly helpful when identical breathing patterns should be reproduced several times. In the following we report on recent developments of flow- and lung simulators from other groups and present our own experiences in Hagen. To study automatic CPAP devices we applied a custom-made simulator which reproduces the obstruction of the upper airway and any breathing waveform. From the different behavior of automatic CPAP devices concerning pressure dynamics important conclusions can be drawn about the real clinical situation.

Automatic CPAP Performance in Patients with Sleep Apnea Plus COPD

Background: Automatic CPAP devices have demonstrated good results in obtaining optimal fixed CPAP pressure to eliminate respiratory events in patients with sleep apnea-hypopnea syndrome (SAHS). However, automatic CPAP has not been fully studied in patients with COPD plus SAHS. Objectives: To analyse the performance of an automatic CPAP in severe COPD patients compared with SAHS patients with no associated co-morbidity. Methods: We compared 10 consecutive patients with SAHS and no associated co-morbidity and 10 patients with SAHS plus severe COPD who required CPAP titration. Automatic CPAP performance was studied during full-night PSG. Inadequate pressure increase periods, absence of pressure increases in reaction to respiratory events, air leak periods, and pressure behaviour in the face of erratic breathing periods were analysed. Results: The SAHS patients without co-morbidities vs. SAHS plus COPD patients presented: mean sleep efficiency, 80.2 (11.5)% vs. 76.5 (12.1)%; residual AHI, 6.3 (5.2) vs. 5.1 (7.7); residual CT90, 1 (3)% vs. 14 (1)%. The device´s performance demonstrates a mean of 1.2 (1.5) vs. 1.3 (1.2) periods of inadequate pressure increases; absence of pressure increases in reaction to respiratory events, 4.1 (5.4) vs. 0.6 (0.7) times; periods of air leaks, 1.3 (3.8) vs. 13.9 (11.7); mean optimal pressure, 9.1 (1.4) vs. 9.0 (1.9) cm H2O. Conclusion: Titration with automatic CPAP could be as effective in patients with SAHS plus severe COPD as in patients with SAHS without COPD. However, the presence of more leakages must be taken into account.

Accuracy of Residual Apnea and Hypopnea Index Detected by Automatic Continuous Positive Airway Pressure Device in Patients With Obstructive Sleep Apnea

PURPOSE: Continuous positive airway pressure (CPAP) is indicated for treatment of obstructive sleep apnea (OSA). Titration is manual during level 1 polysomnography or by automatic CPAP devices (autoCPAP) where fixed CPAP is chosen from autoCPAP data, provided the residual apnea-hypopnea index (R-AHI) is acceptable. Accuracy of R-AHI from autoCPAP has not been well-studied in unmonitored conditions, yet these titrations are typically unattended. This study compares R-AHI scored by Respironics Remstar AutoCPAP to R-AHI scored manually on simultaneous level 3 polysomnography in OSA.

Klinische Aspekte der Biosignalverarbeitung von Atmungsparametern in der Schlafmedizin

Biological signals recorded by polysomnography such as electroencephalograms (EEG), electrooculograms (EOG) und electromyograms (EMG), airflow, thoracic and abdominal motions, O(2) saturation and heart frequency pass through a processing chain with amplification and filtering of the measured variables. In the signal processing the original signal is manipulated to extract information in order to correlate various parameters and to visualise the signal in different representations. The task of the clinician is now to take advantage of the information available and to come to clinical conclusions. Therefore the characteristics, especially the methodology of the signal processing in the devices, should be disclosed by the manufacturers and thus be verifiable. In this review for the example of O(2) saturation, the consequence of different processing criteria with regard to the apnea/hypopnea index is presented. Biosignals such as the respiratory flow are also increasingly being used to control therapy equipment for automatic CPAP devices (APAP). However, the implemented algorithms are often not known, and cannot directly be derived from the polysomnographic records under APAP therapy. In model experiments with a flow generator, defined flow patterns can be simulated. Using bench tests with simulated apneas and waking periods, diagnosed from the flow characteristics, the methods of signal processing can be verified by measuring the pressure profiles and made more transparent for the clinician.

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.

Reliability of home CPAP titration with different automatic CPAP devices

BackgroundCPAP titration may be completed by automatic apparatus. However, differences in pressure behaviour could interfere with the reliability of pressure recommendations. Our objective was to compare pressure behaviour and effective pressure recommendations between three Automatic CPAP machines (Autoset Spirit, Remstar Auto, GK 420).MethodsSixteen untreated obstructive sleep apnea patients were randomly allocated to one of the 3 tested machines for a one-week home titration trial in a crossover design with a 10 days washout period between trials.ResultsThe median pressure value was significantly lower with machine GK 420 (5.9 +/- 1.8 cm H2O) than with the other devices both after one night and one week of CPAP titration (7.4 +/- 1.3 and 6.6 +/- 1.9 cm H2O). The maximal pressure obtained over the one-week titration was significantly higher with Remstar Auto (12.6 +/- 2.4 cm H2O, Mean +/- SD) than with the two other ones (10.9 +/- 1.0 and 11.0 +/- 2.4 cm H2O). The variance in pressure recommendation significantly differed between the three machines after one night and between Autoset Spirit and the two other machines after 1 week.ConclusionPressure behaviour and pressure recommendation significantly differ between Auto CPAP machines both after one night and one week of home titration.

Automatic Titration and Calculation by Predictive Equations for the Determination of Therapeutic Continuous Positive Airway Pressure for Obstructive Sleep Apnea

It is unknown to what extent therapeutic continuous positive airway pressure (CPAP) levels obtained by various methods for the treatment of obstructive sleep apnea syndrome (OSAS) differ. This study aimed to explore the relationships among pressures titrated by an automatic CPAP (APAP) device and those calculated using different predictive equations, and to compare different ranges of calculated pressures with pressure values titrated by APAP. In 140 OSAS patients, the 95th percentile pressure delivered by an APAP device (AutoSet T; ResMed; Sydney, NSW, Australia) during polysomnography, and pressures calculated by three equations (equation 1, Hoffstein and Miljetig [1994]; equation 2, Sériès et al [2000]; and equation 3, Stradling et al [2004]) were compared. Titrated and calculated pressures were weakly correlated. Significant differences were found between the mean (+/- SD) pressures (11.1 +/- 1.6, 8.3 +/- 1.8, 10.5 +/- 1.6, and 10.3 +/- 1.3 cm H(2)O, respectively) for 95th percentile APAP, and pressures calculated by equations 1, 2, and 3, except between values calculated by equations 2and 3. Differences between the calculated and APAP-derived pressures were negative for the low calculated values, and were progressively attenuated, or became positive, for the high values. The differences were smallest for calculated pressures from 11 to > 13 cm H(2)O, which were represented to a greater extent among the values calculated by equations 2 and 3 than by those calculated by equation 1. Considerably different therapeutic CPAP levels may be determined using various methods. The differences between the calculated and APAP-derived pressures are largest for calculated values of < 9 or > 15 cm H(2)O. The clinical consequences of these findings deserve further evaluation. Caution is still required before treating OSAS patients with calculated pressures.

Treatment of obstructive sleep-disordered breathing with positive airway pressure systems

Positive airway pressure systems are widely used to treat patients with moderate-to-severe obstructive sleep-disordered breathing. The application of stable continuous positive airway pressure (CPAP)viathe nose (nasal CPAP) has been the mainstay of treatment since the early 1980s. For treatment to be effective, the pressure level must be fine-tuned to restore patency of the individual patient's upper airway.Currently, there is ongoing controversy concerning which outcomes to observe when adapting the pressure level, and which methods to use for pressure adaptation. Adjusting the pressure level to control apnoeas and hypopnoeas is one major objective, but may not be sufficient to restore normal sleep. Evidence is available that elimination of inspiratory flow limitation leads to better results.In recent years, it has become evident that the use of empirically set CPAP or automatic CPAP devices parallel the clinical results obtained with the classical approach of manual CPAP titration. A striking and still unexplained paradox lies in the fact that automatic CPAP devices perform very differently on the bench, but still yield satisfactory results on several clinical outcomes,e.g.control of sleep-related respiratory disturbances, restoration of good sleep quality and daytime alertness. Understanding the functioning of automatic CPAP devices can prove difficult, as the mode of operation is usually not disclosed by the manufacturers.At present, it is impossible to make any scientifically sound statement on the appropriateness of using automatic continuous positive airway pressure devices for the routine treatment of patients with obstructive sleep-disordered breathing. For this purpose, convincing results of phase I–III clinical trials are needed.

Titration procedures for nasal CPAP: Automatic CPAP or prediction formula?

Background The best method for titration of continuous positive airway pressure (CPAP) therapy in obstructive sleep apnea (OSA) syndrome has not yet been established. The 90th or 95th percentiles of the pressure titrated over time by automatic CPAP (A-CPAP) have been recommended as reference for prescribing therapeutic fixed CPAP (F-CPAP). We compared A-CPAP to F-CPAP, which was determined by a common prediction formula. Methods Forty-five patients who were habituated to F-CPAP underwent titration polysomnography. In a double-blind, randomized order, each patient used an A-CPAP device in the autotitration and in the fixed pressure mode during one half of the night. Apnea–hypopnea index (AHI) and pressure profiles were primary outcomes. Bias and precision were additionally assessed for both CPAP modes. Results No significant differences in various sleep parameters or in subjective sleep quality evaluation were found. The AHI was effectively lowered in both CPAP modes (A-CPAP 7.7 [10.8] events/h versus F-CPAP 5.4 [9.0] events/h, p = 0.061). Comparison of group means showed that F-CPAP closely paralleled mean (Pmean) and median (P50), but not the 95th percentile (P95) pressure, of A-CPAP. While bias was lowest for Pmean and P50, there was a lack of precision in all A-CPAP pressure categories. Conclusions We confirm that F-CPAP set by prediction formula is not worse in terms of AHI control than A-CPAP. On average, F-CPAP parallels Pmean and P50 but not P95. However, due to imprecise matching, individual F-CPAP values cannot be derived from Pmean or P50.

Untersuchungen zur Leckage-Messung von automatischen CPAP-Geräten

An effective CPAP-treatment is only possible, if greater mask-and mouth leakages are prevented. In the case of greater leakages the CPAP decreases and the flow induces side effects as rhinitis and conjunctivitis. In addition to mask-and mouth leakages there exists a leakage through the exhaust valve of the mask which is necessary to avoid CO2-rebreathing. This leakage changes are dependent on the pressure. In many automatic CPAP devices the hard- and software registers the leakage in parallel with the pressure variations. However it is unclear which leakages are considered. We analysed therefore the signal of the leakage of 4 automatic CPAP-devices concerning following questions: Does the leakage measurement of the devices correspond with the pneumotachographically measured flow. How is the leakage of the mask exhaust valve taken into account. We simulated normal breathing with a mechanical ventilator. The respective device was connected by a y-piece with a 5 mm aperture (leakage). With an external flow analyser the flow of the leakage was registered and compared with the flow measured by the automatic CPAP-device. The flow of the devices A to C differed during 10 mbar CPAP from the value of the flow analyser by 5.0 %, 4.3 % and 11.3 %. The software of device D subtracts the leakage through the mask exhaust valve so that the indicated leakage corresponds with the mouth and mask leakage. The leakage was sufficiently well recorded by the tested automatic devices. When evaluating the leakage signal the flow through the mask exhaust valve should be taken into account.

Continuous Positive Airway Pressure Used by Adults With Obstructive Sleep Apneas After Prescription in a Public Referral Hospital in Mexico City

The aim of this study was to analyze the frequency of initiation of continuous positive airway pressure (CPAP) in patients with obstructive sleep apnea syndrome (OSAS) in a referral hospital in Mexico City serving mainly patients without public health insurance coverage and to assess their level of adherence. Patients with OSAS diagnosed by polysomnography or by simplified respiratory polygraphy for whom nasal CPAP was prescribed were enrolled in the study. Titration of CPAP was performed during polysomnography or with an automatic CPAP device. Compliance with treatment was assessed during a medical visit or by telephone interview. A total of 304 patients were enrolled upon prescription of nasal CPAP; 169 (55.5%) either purchased a device or were provided with one by the social security system. The patients most seriously ill and who had public health insurance coverage were the ones who most often acquired a device. These patients took 1.5 months to obtain the equipment and had a compliance rate of 80% at a mean 34 months of follow-up. The respiratory events index was correlated with compliance, whereas excessive daytime sleepiness (Epworth scale score) and body mass index were predictors of therapeutic CPAP pressure. Nearly half the patients who were prescribed CPAP did not acquire the device. Most of those who acquired a device adhered to the treatment. In Mexico access to procedures for diagnosing OSAS is limited and access to treatment is also restricted for patients who do not have public health insurance coverage.

Model study on the change of the pressure applied by automatic CPAP devices when subjected to simulated respiratory events with and without increases in upper airway resistance

Model study on the change of the pressure applied by automatic CPAP devices when subjected to simulated respiratory events with and without increases in upper airway resistance

Protocolo para evaluar una CPAP automática. Valoración de la utilidad del Autoset-T para determinar la presión de Cpap óptima en el síndrome de apnea-hipopnea del sueño

Given the high prevalence of sleep apnea/hypopnea syndrome (SAHS) and great demand for conventional polysomnography (PSG) and long waiting lists, alternative means for diagnosing SAHS and titrating continuous positive airway pressure (CPAP) are needed. Automatic CPAP may play a role in meeting the last objective, not only for treatment but also for suggesting the optimum CPAP setting. a) To define a protocol to assess the functioning of an automatic CPAP device by means of a mechanical model; b) to determine the behavior of automatically adjusted CPAP during PSG; c) to define the usefulness of automatic CPAP for indicating optimal CPAP pressure for patients with SAHS; d) to evaluate the efficacy of the automatically indicated pressure setting against conventional PSG. Four protocols were carried out using the Autoset-T (AT) device. 1. Apneas, hypopneas, flow limitation, snoring and normal flow were simulated in a laboratory using a mechanical model in order to check AT functioning. 2. The behavior of the automatically adjusted CPAP was observed in real time during PSG in 12 patients with severe SAHS. 3. The agreement of CPAP titrated with the AT and with PSG was checked in a group of 39 patients with SAHS. 4. The efficacy of the CPAP pressure recommended by the AT was checked by PSG in a group of 14 patients with SAHS. With the AT, CPAP increased rapidly in response to apneas or snoring in the mechanical model and during conventional PSG; it took only a mean 2.8 3.1 min to rise from a baseline pressure of 4 cm H2O to a near-optimum pressure of 11 1 cm H2O. Once normal flow was reached CPAP slowly decreased, responding with great sensitivity to the slightest abnormality, especially snoring, but not changing in response to certain types of flow limitation. The pressure read visually on the AT was similar to the one recommended by PSG in most of the 39 patients (71%). The PSG performed after one month of using AT-recommended CPAP titration confirmed that the number of apneas, hypopneas (apnea/hypopnea index 6(1) and arousals (8 2) was normal for these SAHS patients. The AT increases pressure rapidly in the presence of respiratory events and maintains a normal breathing pattern in most patients. Visual reading of the AT pressure allows correct identification of the optimal CPAP setting for SAHS treatment.