Comparison of manual titration and automatic titration based on forced oscillation technique, flow and snoring in obstructive sleep apnea

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.

Different Continuous Positive Airway Pressure Titration Modalities in Obstructive Sleep Apnea Syndrome Patients

Background

Patients with obstructive sleep apnea syndrome are mainly treated with continuous positive airway pressure. Polysomnography-guided full-night manual titration is the gold standard for continuous positive airway pressure titration, but it is cost-, time-, and effort-consuming. Alternative ways of titration are easier with less cost, time, and effort. In the era of the COVID-19 pandemic, the need to establish more safe strategies is increased.

Aim

To choose a rapid, efficient, simple, and safe method with less effort and cost in the measurement of a suitable level of positive airway pressure in the management of obstructive sleep apnea syndrome.

Methods

This study enrolled 48 adult patients who had been diagnosed with obstructive sleep apnea syndrome at our sleep unit and were candidates for treatment with continuous positive airway pressure according to AASM 2008 after exclusion of other sleep-related breathing disorders. All patients underwent both laboratory full-night manual titration and auto-titration (by Prisma20A of WEINMANN medical technology, Germany). Manual titration pressure and P95 of auto-titration were obtained and compared with calculated pressures by five predictive formulas (Miljeteig and Hoffstein, Sériès, Stradling, Loredo, and Lee).

Results

Patients included in the study were 25 females (52.1%) and 23 males (47.9%) with a mean±SD of age of 49.98±10.36 years. Mean±SD of manual pressure was 10.44±2.49 cmH₂O, P95 was 10.16±2.64 cmH₂O, and calculated pressures by different equations were: Miljeteig and Hoffstein, 8.53±2.03; Sériès, 11.40±1.81; Stradling, 9.68±1.65; Loredo, 9.90±1.79; and Lee, 10.61±2.68 cmH₂O. No significant differences were reported between manual pressure and pressures of auto-titration with Sériès, Stradling, Loredo, and Lee equations (p=0.112, 0.09, 0.212, 0.213, and 0.657, respectively).

Conclusion

Auto-titration can be used as an effective alternative to manual titration with less cost and effort and is more comfortable to patients. Predictive formulas can be used instead of standard and auto-titration especially in resource-limited facilities and in pandemics.

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.

Verifying the Relative Efficacy between Continuous Positive Airway Pressure Therapy and Its Alternatives for Obstructive Sleep Apnea: A Network Meta-analysis

Obstructive sleep apnea (OSA) is a common breathing disorder, and continuous positive airway pressure (CPAP) therapy together with its alternatives has been developed to treat this disease. This network meta-analysis (NMA) was aimed to compare the efficacy of treatments for OSA. Cochrane Library, MEDLINE, and Embase were searched for eligible studies. A conventional and NMA was carried out to compare all therapies. Sleeping characteristics, including Apnea–Hypopnea Index (AHI), Epworth Sleepiness Scale (ESS), arterial oxygen saturation, and arousal index (AI), and changes of blood pressure were selected as outcomes. A total of 84 studies were finally included after rigorous screenings. For the primary outcomes of AHI and ESS, the value of auto-adjusting positive airway pressure (APAP), CPAP, and oral appliance (OA) all showed statistically reduction compared with inactive control (IC). Similar observation was obtained in AI, with treatments of the three active interventions. A lower effect of IC in SaO₂ was exhibited when compared with APAP, CPAP, and OA. Similar statistically significant results were presented in 24 h systolic blood pressure and 24 h DBP when comparing with CPAP. Our NMA identified CPAP as the most efficacious treatment for OSA patients after the evaluation of sleeping characteristics and blood pressures. In addition, more clinical trials are needed for further investigation due to the existence of inconsistency observed in this study.

Mathematical Equations to Predict Positive Airway Pressures for Obstructive Sleep Apnea: A Systematic Review

Objective. To systematically review the international literature for mathematical equations used to predict effective pressures for positive airway pressure (PAP) devices. Methods. Google Scholar, PubMed, Scopus, Embase, Web of Science, CINAHL, and The Cochrane Library were searched through June 27, 2015. The PRISMA statement was followed. There was no language limitation. Results. 709 articles were screened, fifty were downloaded, and twenty-six studies presented equations that met the inclusion and exclusion criteria. In total, there were 4,436 patients in the development phases and 3,489 patients in the validation phases. Studies performed multiple linear regressions analyses as part of the equation(s) development and included the following variables: physical characteristics, polysomnography data, behavioral characteristics, and miscellaneous characteristics, which were all predictive to a variable extent. Of the published variables, body mass index (BMI) and mean oxygen saturation are the most heavily weighted, while BMI (eighteen studies), apnea-hypopnea index (seventeen studies), and neck circumference (eleven studies) were the variables most frequently used in the mathematical equations. Ten studies were from Asian countries and sixteen were from non-Asian countries. Conclusion. This systematic review identified twenty-six unique studies reporting mathematical equations which are summarized. Overall, BMI and mean oxygen saturation are the most heavily weighted.

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

BACKGROUND AND OBJECTIVE

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.

METHODS

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.

RESULTS

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).

CONCLUSIONS

The results suggest that automatic titration pressure derived from REMstar Auto is usually higher than the pressure derived from manual titration.

Wireless Wearable Multisensory Suite and Real-Time Prediction of Obstructive Sleep Apnea Episodes

Obstructive sleep apnea (OSA) is a common sleep disorder found in 24% of adult men and 9% of adult women. Although continuous positive airway pressure (CPAP) has emerged as a standard therapy for OSA, a majority of patients are not tolerant to this treatment, largely because of the uncomfortable nasal air delivery during their sleep. Recent advances in wireless communication and advanced ("bigdata") preditive analytics technologies offer radically new point-of-care treatment approaches for OSA episodes with unprecedented comfort and afforadability. We introduce a Dirichlet process-based mixture Gaussian process (DPMG) model to predict the onset of sleep apnea episodes based on analyzing complex cardiorespiratory signals gathered from a custom-designed wireless wearable multisensory suite. Extensive testing with signals from the multisensory suite as well as PhysioNet's OSA database suggests that the accuracy of offline OSA classification is 88%, and accuracy for predicting an OSA episode 1-min ahead is 83% and 3-min ahead is 77%. Such accurate prediction of an impending OSA episode can be used to adaptively adjust CPAP airflow (toward improving the patient's adherence) or the torso posture (e.g., minor chin adjustments to maintain steady levels of the airflow).

Evaluation of a noninvasive algorithm for differentiation of obstructive and central hypopneas

STUDY OBJECTIVES

The clear discrimination of central and obstructive hypopneas is highly relevant to avoid misinterpretation and inappropriate treatment of complicated breathing patterns. Esophageal manometry is the accepted standard for the differentiation of the phenotypes of sleep apnea. However, it is limited in its use due to poor acceptance by patients and therefore rarely performed in routine clinical practice. Flattening of the inspiratory airflow curve, paradoxical breathing, arousal position, sleep stages, and breathing pattern at the end of the hypopnea can each give hints for the classification of hypopnea. The aim of this study was to evaluate a standardized algorithm combining these polysomnographic parameters for the discrimination of hypopneas in everyday practice.

METHODS

Polysomnography (PSG) and esophageal manometry were performed in 41 patients suspected of having sleep apnea (33 male, 52.3 ± 15.9 yr, body mass index 28.6 ± 4.5 kg/m(2)). Hypopneas were independently discriminated by blinded investigators based on esophageal pressure and the PSG-based algorithm. Only those hypopneas that could be differentiated with both methods were evaluated.

RESULTS

There were 1,175 of 1,837 hypopneas (64%) that could be defined by esophageal pressure, 1,812 (98.6%) by the PSG-based algorithm. Using esophageal pressure as a reference, the new algorithm correctly defined 76.9% of central and 60.5% of obstructive hypopneas. The overall accuracy was 68%. The isolated analysis of single PSG parameters revealed a lower accuracy compared with the combined algorithm.

CONCLUSIONS

The PSG-based algorithm allows for discrimination of most hypopneas. It is advantageous in comparison with esophageal pressure because it is noninvasive and less impaired by artefacts. Therefore, it is a potentially helpful tool for sleep specialists.

CITATION

Randerath WJ; Treml M; Priegnitz C; Stieglitz S; Hagmeyer L; Morgenstern C. Evaluation of a noninvasive algorithm for differentiation of obstructive and central hypopneas. SLEEP 2013;36(3):363-368.

Respiratory mechanics measured by forced oscillations during mechanical ventilation through a tracheal tube

The forced oscillation technique (FOT) allows the measurement of respiratory mechanics in the intensive care setting. The aim of this study was to compare the FOT with a reference method during mechanical ventilation through a tracheal tube. The respiratory impedance spectra were measured by FOT in nine anaesthetized pigs, and resistance and compliance were estimated on the basis of a linear resistance-compliance inertance model. In comparison, resistance and compliance were quantified by the multiple linear regression analysis (LSF) of conventional ventilator waveforms to the equation of motion. The resistance of the sample was found to range from 6 to 21 cmH(2)O s l(-1) and the compliance from 12 to 32 ml cmH(2)O(-1). A Bland-Altman analysis of the resistance resulted in a sufficient agreement (bias -0.4 cmH(2)O s l(-1); standard deviation of differences 1.4 cmH(2)O s l(-1); correlation coefficient 0.93) and test-retest reliability (coefficient of variation of repeated measurements: FOT 2.1%; LSF 1.9%). The compliance, however, was poor in agreement (bias -8 ml cmH(2)O(-1), standard deviation of differences 7 ml cmH(2)O(-1), correlation coefficient 0.74) and repeatability (coefficient of variation: FOT 23%; LSF 1.7%). In conclusion, FOT provides an alternative for monitoring resistance, but not compliance, in tracheally intubated and ventilated subjects.

Is automatic CPAP titration as effective as manual CPAP titration in OSAHS patients? A meta-analysis

PURPOSE

It is costly and time-consuming to conduct the standard manual titration to identify an effective pressure before continuous positive airway pressure (CPAP) treatment for obstructive sleep apnea (OSA) patients. Automatic titration is cheaper and more easily available than manual titration. The purpose of this systematic review was to evaluate the effect of automatic titration in identifying a pressure and on the improvement of apnea/hyponea index (AHI) and somnolence, the change of sleep quality, and the acceptance and compliance of CPAP treatment, compared with the manual titration.

METHODS

A systematic search was made of the PubMed, EMBASE, Cochrane Library, SCI, China Academic Journals Full-text Databases, Chinese Biomedical Literature Database, Chinese Scientific Journals Databases and Chinese Medical Association Journals. Randomized controlled trials comparing automatic titration and manual titration were reviewed. Studies were pooled to yield odds ratios (OR) or mean differences (MD) with 95% confidence intervals (CI).

RESULTS

Ten trials involving 849 patients met the inclusion criteria. It is hard to identify a trend in the pressures determined by either automatic or manual titration. Automatic titration can improve the AHI (MD = 0.03/h, 95% CI = -4.48 to 4.53) and Epworth sleepiness scale (SMD = -0.02, 95% CI = -0.34 to 0.31,) as effectively as the manual titration. There is no difference between sleep architecture under automatic titration or manual titration. The acceptance of CPAP treatment (OR = 0.96, 95% CI = 0.60 to 1.55) and the compliance with treatment (MD = -0.04, 95% CI = -0.17 to 0.10) after automatic titration is not different from manual titration.

CONCLUSION

Automatic titration is as effective as standard manual titration in improving AHI, somnolence while maintaining sleep quality similar to the standard method. In addition, automatic titration has the same effect on the acceptance and compliance of CPAP treatment as manual titration. With the potential advantage of time and cost savings, automatic titration was recommended to be applied in identifying a proper pressure for CPAP treatment instead of manual titration in clinical practice.

APAP and Alternative Titration Methods

PURPOSE OF REVIEW: Positive airway pressure therapy (PAP) is commonly prescribed treatment for obstructive sleep apnea (OSA). Traditionally, the determination of the optimal pressure for treatment of sleep-disordered breathing was made by manual titration of the device by a sleep technician in attendance during polysomnography. However, the advent of alternative methods for determination of optimal PAP - such as auto-titrating PAP (APAP) - has seen tremendous growth over the past decade. The purpose of this review is to improve our understanding of the currently available alternative methods for titration of PAP in patients with sleep-disordered breathing (SDB) with special emphasis on obstructive sleep apnea. RECENT FINDINGS: Recent prospective-randomized studies of alternative methods of titration suggest that pressure determinations made by such devices are comparable to traditional manual titrations made in the sleep laboratory. Obstacles to the adoption of such alternative modes of titration into day-to-day practice may be attributable to issues surrounding appropriate patient selection, differences between devices, re-imbursement policies of third party payors, consensus amongst sleep experts, and individual physicians' practice patterns and volumes. While newer generations and types of auto-titrating PAP devices are entering the sleep field constantly, providers' knowledge and time availability remain limiting factors. SUMMARY: There is tremendous growth in the technology and scientific evidence in support of alternative modes of PAP titration for sleep-disordered breathing, but barriers to implementation remain.