The art and science of continuous positive airway pressure therapy in obstructive sleep apnea

Transition from APAP to CPAP may be a cost-effective health intervention in OSA patients

OBJECTIVE

Obstructive sleep apnea (OSA) is a common disorder associated with a significant economic burden. Continuous positive airway pressure (CPAP) and auto-titrating positive airway pressure (APAP) are recognized therapeutic options in patients with OSA, although treatment costs are higher with APAP. We conducted a study aimed at evaluating the effectiveness and potential cost savings resulting from the implementation of a protocol guiding the transition to CPAP in OSA patients previously treated with APAP.

METHODS

This prospective study included patients with OSA under APAP who were followed up at the Sleep Medicine outpatient clinic of a tertiary referral hospital between January 2019 and January 2021. Treatment was switched to CPAP in patients who met the following criteria: satisfactory adaptation and adherence to APAP, residual apnea-hypopnea index (AHI) of < 5/hour, and no relevant air leaks. APAP and CPAP outcomes were compared and an estimate of the savings obtained by the transition from APAP to CPAP was calculated.

RESULTS

Ninety-three patients were included in the study. APAP and CPAP were both effective in correcting obstructive events and improving daytime sleepiness. No significant differences were found regarding treatment adherence and tolerance between both PAP modalities. The selection of fixed-pressure CPAP through 90th or 95th percentile APAP pressure proved to be effective and an alternative strategy to titration polysomnography. At the end of this two-year study, the transition from APAP to CPAP enabled savings of at least 10,353€.

CONCLUSION

The transition from APAP to CPAP may be an effective, well-tolerated, safe, and cost-saving strategy in patients with OSA.

Machine learning-based prediction of adherence to continuous positive airway pressure (CPAP) in obstructive sleep apnea (OSA)

Continuous positive airway pressure (CPAP) is the "gold-standard" therapy for obstructive sleep apnea (OSA), but the main problem is the poor adherence. Therefore, we have searched for the causes of poor adherence to CPAP therapy by applying predictive machine learning (ML) methods. The study was conducted on OSAs in nighttime therapy with CPAP. An outpatient follow-up was planned at 3, 6, 12 months. We collected several parameters at the baseline visit and after dividing all patients into two groups (Adherent and Non-adherent) according to therapy adherence, we compared them. Statistical differences between the two groups were not found according to baseline characteristics, except gender (P< .01). Therefore, we applied ML to predict CPAP adherence, and these predictive models showed an accuracy and sensitivity of 68.6% and an AUC (area under the curve) of 72.9% through the SVM (support vector machine) classification method. The identification of factors predictive of long-term CPAP adherence is complex, but our proof of concept seems to demonstrate the utility of ML to identify subjects poorly adherent to therapy. Therefore, application of these models to larger samples could aid in the careful identification of these subjects and result in important savings in healthcare spending.

The public health burden of obstructive sleep apnea

Obstructive sleep apnea (OSA) is the most common respiratory disorder of sleep. The vast majority (>80%) of adults with moderate to severe OSA remain undiagnosed. The economic costs associated with OSA are substantial for both the individual and society as a whole; expenses are likely to be underestimated given that the disease remains undiagnosed in such a large percentage of individuals. The economic burden of motor vehicle collisions related to OSA alone is significant; it is estimated that 810,000 collisions and 1400 fatalities from car crashes in the United States were attributable to sleep apnea in 2000. The many health consequences of OSA include daytime sleepiness, reduced quality of life, decreased learning skills, and importantly, neurocognitive impairments that include impaired episodic memory, executive function, attention and visuospatial cognitive functions. Untreated OSA leads to numerous medical problems such as cardiovascular diseases that can potentially increase healthcare utilization. Untreated patients with sleep apnea consume a disproportionate amount of healthcare resources, expenditures that decrease after treatment. The gold-standard management of OSA remains treatment with CPAP (Continuous Positive Airway Pressure), which is effective in eliminating sleep fragmentation and preserving nocturnal oxygenation, thereby improving daytime sleepiness and quality of life. However, its impacts in reversing neurocognitive function are still uncertain. A significant impediment to CPAP effectiveness is low adherence rates (ranges from 50% to 75%). It is commonly accepted that CPAP improves excessive drowsiness; hence meliorates attention, and accumulating data suggest that CPAP improves a variety of other outcomes such as the risk of motor vehicle crashes.

The differences in plasma/serum ghrelin levels between obstructive sleep apnea-hypopnea patients and controls: A protocol for systematic review and meta-analysis

BACKGROUND

The association between obstructive sleep apnea-hypopnea syndrome (OSAHS) and plasma/serum ghrelin levels remains controversial. We performed a meta-analysis to evaluate the difference in plasma/serum ghrelin levels between OSAHS patients and controls.

METHODS

Database of PubMed, SCI, and Elsevier were searched entirely. Two independents identified eligible studies of ghrelin levels in OSAHS patients. ReviewManager (version 5.3) was adopted for data synthesis.

RESULTS

The meta-analysis A pooled the comparison of ghrelin concentrations in OSAHS patients and controls, which included 7 studies and involving 446 participants. The result of the meta-analysis A indicated that plasma/serum ghrelin levels were no significant differences between the OSAHS group and the control group (standard mean difference (SMD) = 0.08, 95% confidence interval (CI) = -0.12 to 0.28, P = .43). As a supplementary, meta-analysis B pooled the comparison of plasma/serum ghrelin levels in OSAHS patients before and after continuous positive airway pressure (CPAP) therapy, which included 155 participants from 4 studies, it revealed that plasma/serum ghrelin levels were no significant differences between before and after CPAP therapy (SMD = 0.12, 95%CI = -0.07 to 0.31, P = .22).

CONCLUSION

The meta-analysis A demonstrated that plasma/serum ghrelin levels were no significant differences between the OSAHS group and the control group. The meta-analysis B showed plasma/serum ghrelin levels have no significant changes after CPAP therapy in OSAHS patients.

Effectiveness of nasal continuous airway pressure therapy in patients with obstructive sleep apnea

OBJECTIVES

A prospective observational study was carried out with the aim of evaluating the effectiveness of nasal continuous positive airway pressure (nCPAP) therapy on the health-related quality of life (QoL) of patients with obstructive sleep apnea (OSA).

METHODS

The patients included in this study were those recently diagnosed with OSA (AHI > 5) and given nCPAP therapy, as well as being referred to a sleep laboratory for an assessment of their sleep disordered breathing. Prior to the start of nCPAP therapy and polysomnography evaluation, patients were asked to complete the validated Quebec sleep questionnaire (QSQ), and their baseline measurements were recorded.

RESULTS

Among the study population, 14.41% (n = 31) had mild OSA with an apnea and hypopnea index of 5 to 14.9 events/h, while 26.97% (n = 58) had moderate OSA and 40% (n = 86) had severe OSA. The overall average apnea and hypopnea index of the study population was 30.24 ± 9.73 events/h; mild OSA patients had an average apnea and hypopnea index of 10.09 ± 2.65 events/h, moderate OSA patients had 21.48 ± 4.40 events/h, and severe OSA patients had 59.16 ± 22.14 events/h. A significant difference was observed between the scores before treatment and after 6 months of therapy in all domains of the QSQ QoL scores (P < 0.0001).

CONCLUSION

Nasal continuous positive airway pressure treatment improved the QoL for patients with mild, moderate, and severe sleep apnea.

Acute impact of continuous positive airway pressure on nasal patency

BACKGROUND

Continuous airflow in the upper airway can cause discomfort, leading to nasopharyngeal complaints. The aim of the present study is to evaluate the acute effects of continuous positive upper-airway pressure on nasal patency in awake normal subjects.

METHODS

Twenty-seven adults (17 men; 10 women; age range, 18 to 43 years) were exposed to continuous airway pressure (20 cmH₂ O) in the nasal cavity, delivered by a continuous positive airway pressure (CPAP) device through a nasal mask for 2 hours. Visual analogue scale (VAS) of nasal obstruction, Nasal Obstruction Symptom Evaluation (NOSE) modified scale, acoustic rhinometry (AR), and peak nasal inspiratory flow (PF) were measured before and after the use of CPAP.

RESULTS

There was an increase in nasal obstruction scores both on the VAS (p < 0.05) and on the NOSE scale (p < 0.05), as well as a reduction in nasal cavity volume on AR (p < 0.05) and a decline in PF (p < 0.05). Subjects were stratified into 2 groups: with and without symptoms of allergic rhinitis. Nasal parameters were significantly worse in the rhinitis group, with higher nasal obstruction scores on the VAS (p = 0.001) and NOSE scale (p < 0.001) and decreased PF (p < 0.001).

CONCLUSION

Acute exposure to positive pressure via CPAP is associated with subjective and objective reductions in nasal patency. In individuals with allergic nasal symptoms, deterioration is even more severe than in patients without these symptoms.

Effect of Continuous Positive Airway Pressure on Adiponectin in Patients with Obstructive Sleep Apnea: A Meta-Analysis

Objective

Obstructive sleep apnea (OSA) has been suggested to be associated with low levels of adiponectin. Continuous positive airway pressure (CPAP) is the gold standard treatment for OSA; however, previous studies assessing the effect of CPAP on adiponectin in patients with OSA yielded conflicting results. The present meta-analysis was performed to determine whether CPAP therapy could increase adiponectin levels.

Methods

Two reviewers independently searched PubMed, Cochrane library, Embase and Web of Science before February 2015. Information on characteristics of subjects, study design and pre- and post-CPAP treatment of serum adiponectin was extracted for analysis. Standardized mean difference (SMD) was used to analyze the summary estimates for CPAP therapy.

Results

Eleven studies involving 240 patients were included in this meta-analysis, including ten observational studies and one randomized controlled study. The meta-analysis showed that there was no change of adiponectin levels before and after CPAP treatment in OSA patients (SMD = 0.059, 95% confidence interval (CI) = −0.250 to 0.368, z = 0.37, p = 0.710). Subgroup analyses indicated that the results were not affected by age, baseline body mass index, severity of OSA, CPAP therapy duration, sample size and racial differences.

Conclusions

This meta-analysis suggested that CPAP therapy has no impact on adiponectin in OSA patients, without significant changes in body weight. Further large-scale, well-designed long-term interventional investigations are needed to clarify this issue.

Effect of continuous positive airway pressure on leptin levels in patients with obstructive sleep apnea: a meta-analysis

OBJECTIVES

Continuous positive airway pressure (CPAP) is an effective treatment for obstructive sleep apnea hypopnea syndrome (OSAHS), but previous studies assessing the effect of CPAP on leptin in patients with OSAHS yielded conflicting results. In this study, we conducted a meta-analysis to determine whether CPAP therapy could reduce serum leptin levels.

DATA SOURCES

Databases of PubMed, Elsevier, and SCI were thoroughly searched by 2 independent reviewers.

METHODS

RevMan (version 5.2) was used for data synthesis. Weighted mean difference (WMD) before and after CPAP therapy was calculated to estimate the effects of CPAP therapy.

RESULTS

A total of 11 studies involving 413 participants were included. Meta-analysis showed that the total WMD for leptin levels was 1.44 units (95% confidence interval: 1.11-1.77, P < .01) before and after CPAP therapy. Subgroup analysis exhibited that leptin was decreased within 3 days after the therapy, and it was further reduced within 1 to 3 months and beyond.

CONCLUSIONS

The results of our meta-analysis showed that CPAP could significantly reduce leptin levels in OSAHS patients without concomitant weight loss.

Lipid profile after long-term APAP in OSA patients

PURPOSE

This study aimed to explore the impact of an 8-year therapy with autoadjusting positive airway pressure (APAP) on fasting lipid level in a sample of Portuguese moderate/severe obstructive sleep apnea (OSA) patients. Besides contributing to the comprehension of the complex relationship between dyslipidemia and OSA, it provided new data regarding the effectiveness of a long term APAP treatment.

METHODS

Thirty-nine male patients with moderate to severe OSA were included in the study. APAP was prescribed to all patients. Fifteen patients were under lipid-lowering medication throughout the study, and another 15 patients never used lipid-lowering medication at any time during the study. Fasting morning venous blood samples were collected at three time points (baseline 6 months and 8 years) and lipids were estimated. Statistical analysis was performed using Statistical Package for the Social Sciences (SPSS) 21.0 software.

RESULTS

After 8 years of APAP treatment, patients presented a similar body mass index but a significantly less severe daytime sleepiness. Patients on lipid-lowering medication exhibited a higher reduction in total cholesterol than those naïf from that medication, but the reduction was not statistically significant after adjusting for medication and APAP adherence.

CONCLUSIONS

Long-term APAP treatment improves OSA but does not seem to contribute to changes in fasting lipids.

New frontiers in obstructive sleep apnoea

OSA (obstructive sleep apnoea), the most common respiratory disorder of sleep, is caused by the loss of upper airway dilating muscle activity during sleep superimposed on a narrow upper airway. This results in recurrent nocturnal asphyxia. Termination of these events usually requires arousal from sleep and results in sleep fragmentation and hypoxaemia, which leads to poor quality sleep, excessive daytime sleepiness, reduced quality of life and numerous other serious health consequences. Furthermore, patients with untreated sleep apnoea are at an increased risk of hypertension, stroke, heart failure and atrial fibrillation. Although there are many predisposing risk factors for OSA, including male gender, endocrine disorders, use of muscle relaxants, smoking, fluid retention and increased age, the strongest risk factor is obesity. The aim of the present review is to focus on three cutting-edge topics with respect to OSA. The section on animal models covers various strategies used to simulate the physiology or the effects of OSA in animals, and how these have helped to understand some of the underlying mechanisms of OSA. The section on diabetes discusses current evidence in both humans and animal models demonstrating that intermittent hypoxia and sleep fragmentation has a negative impact on glucose tolerance. Finally, the section on cardiovascular biomarkers reviews the evidence supporting the use of these biomarkers to both measure some of the negative consequences of OSA, as well as the potential benefits of OSA therapies.

Treatment for sleep apnea by continuous positive airway pressure improves levels of inflammatory markers - a meta-analysis

BACKGROUND

Obstructive sleep apnea (OSA) is associated with coronary artery disease (CAD). Intermittent hypoxia associated with OSA increases sympathetic activity and may cause systemic inflammation, which may contribute to CAD in patients with OSA. Treatment with continuous positive airway pressure (CPAP) has been shown to change levels of inflammatory markers. We analyzed data from published studies by a systematic meta-analysis.

OBJECTIVE

To asses if treatment for sleep apnea by CPAP will affect levels of inflammatory markers.

DATA RESOURCES

PubMed, Embase and Cochrane library.

METHODS

Study eligibility criteria full text English studies of adult, human subjects, addressing values of at least one of the inflammatory markers before and after CPAP treatment. We used the definition of OSA as an apnea-hypopnea index (AHI) of ≥ 5/h, reported values in mean and standard deviation or median with range.

PARTICIPANTS

Adult, human.

INTERVENTIONS

CPAP treatment for OSA.

STUDY APPRAISAL AND SYNTHESIS METHOD

A total of 3835 studies were reviewed for inclusion, while 23 studies pooled for analysis. A total of 14 studies with 771 patients were pooled for C-reactive protein (CRP); 9 studies with 209 patients were pooled for tumor necrosis factor-alpha (TNF-α); and 8 studies with 165 patients were pooled for interleukin-6 (IL-6).

ENDPOINT DEFINITIONS

THE FOLLOWING INFLAMMATORY MARKERS WERE CHOSEN: CRP, TNF-α, and IL-6.

RESULTS

C-reactive protein: Study level means ranged from 0.18 to 0.85 mg/dl before CPAP treatment and 0.10 to 0.72 mg/dl after CPAP treatment. Mean differences, at a study level, ranged from -0.05 to 0.50. The pooled mean difference was 0.14 [95% confidence interval 0.08 to 0.20, p < 0.00001]. There was heterogeneity in this endpoint (df = 13, p < 0.00001, I(2) = 95%). Tumor necrosis factor-α: Study level means ranged from 1.40 to 50.24 pg/ml before CPAP treatment and 1.80 to 28.63 pg/ml after CPAP treatment. Mean differences, at a study level, ranged from -1.23 to 21.61. The pooled mean difference was 1.14 [95% confidence interval 0.12 to 2.15, p = 0.03]. There was heterogeneity in this endpoint (df = 8, p < 0.00001, I2 = 89%). Interleukin-6: Study level means ranged from 1.2 to 131.66 pg/ml before CPAP treatment and 0.45 to 66.04 pg/ml after CPAP treatment. Mean differences, at a study level, ranged from -0.40 to 65.62. The pooled mean difference was 1.01 [95% confidence interval -0.00 to 2.03, p = 0.05]. There was heterogeneity in this endpoint (df = 7, p < 0.00001, I(2) = 95%).

LIMITATIONS

Only published data. Studies pooled were mainly small, non-randomized trials.

CONCLUSION

Sleep apnea treatment with CPAP improves levels of inflammatory markers.

Association between sleep disorders, obesity, and exercise: a review

Decreased sleep duration and quality is associated with an increase in body weight and adiposity. Insomnia, obstructive sleep apnea, and restless legs syndrome are three of the most prevalent types of sleep disorder that lead to an increased risk for numerous chronic health conditions. Various studies have examined the impact of these sleep disorders on obesity, and are an important link in understanding the relationship between sleep disorders and chronic disease. Physical activity and exercise are important prognostic tools in obesity and chronic disease, and numerous studies have explored the relationship between obesity, sleep disorders, and exercise. As such, this review will examine the relationship between sleep disorders and obesity. In addition, how sleep disorders may impact the exercise response and how exercise may impact patient outcomes with regard to sleep disorders will also be reviewed.

Continuous positive airway pressure and type 2 diabetes mellitus

Obstructive sleep apnea (OSA) is a sleep disorder, increasingly recognized. It is commonly present in obese persons, treated with continuous positive airway pressure (CPAP), being the gold standard. The disorder has been associated with diabetes mellitus and possibly related to hypoxia per se, increased sympathetic activity, disturbed hypothalamic-pituitary-adrenal axis and increased inflammatory cytokines and leptin, all of which can adversely affect both glucose metabolism and insulin sensitivity. Given this association and the presence of common risk factors, this review assessed the impact of CPAP on diabetes mellitus through various metabolic parameters including HbA1c, nocturnal glucose and insulin resistance, in addition to the effect of CPAP on the prevention of diabetes mellitus. Results have been conflicting; Randomized controlled trials are recommended to allow objective and definite conclusions.

Continuous positive airway pressure treatment: effect on serum lipids in patients with obstructive sleep apnoea

Obstructive Sleep Apnoea (OSA) is a common disorder in adults. Its hallmark is repetitive episodes of partial or complete obstruction of the upper airway during sleep associated with increasing respiratory efforts. This leads to oxyhaemoglobin desaturation, sleep fragmentation, and daytime symptoms, mainly excessive sleepiness. Accumulating evidence suggests that intermittent hypoxia and oxyhaemoglobin desaturation may, irrespective of obesity, lead to elevation of serum lipids even in non-dyslipidaemic OSA patients. Continuous Positive Airway Pressure (CPAP) is the treatment of choice for OSA, since it eliminates upper airway collapse during sleep and improves sleep fragmentation, daytime symptoms and quality of life. Moreover, it has been proposed that the amelioration of breathing disturbances during sleep can improve several markers of the lipid profile, such as total cholesterol, triglycerides, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol as well as apolipoproteins A, B and C. Indeed, some studies have reported improvements in these parameters especially in CPAP adherent patients. However, other studies failed to confirm this beneficial effect. The present article reviews the issue whether CPAP treatment exerts a beneficial effect on lipids.

Continuous positive airway pressure to improve insulin resistance and glucose homeostasis in sleep apnea

Obstructive sleep apnea syndrome (OSAS) is a relatively common disorder in the adult population. It is associated with alterations in glucose metabolism and increases the risk for diabetes mellitus. Continuous positive airway pressure (CPAP) is the treatment of choice for OSAS. It may also have a favorable effect on insulin resistance and glucose metabolism, although relevant data is conflicting. Additional research is still needed to fully establish the effect of CPAP on glucose homeostasis. It should ascertain which patients may benefit most and how long treatment takes to induce favorable changes. Finally, patient compliance is being appreciated as a major factor influencing therapeutic outcomes, and this needs to be further examined.

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.

Sleep apnea and psychological functioning in chronic fatigue syndrome

Objectives were to explore: (1) whether sleep apnea/hypopnea syndrome (SAHS) should be considered a chronic fatigue syndrome (CFS) comorbidity, rather than a diagnostic exclusion criterion; and (2) to compare sleep/wake/ psychopathology in individuals with CFS, controls and another illness. Participants (CFS, SAHS, controls) completed questionnaires and were evaluated for SAHS; 68 percent were subsequently diagnosed with SAHS. CFS participants with and without SAHS did not differ. Both clinical groups were less well adjusted than controls. We conclude that SAHS should not be an exclusion criterion for CFS and that psychological problems in CFS seem a consequence of coping with illness.

The price of obstructive sleep apnea-hypopnea: hypertension and other ill effects

This review addresses the cardiovascular, cerebrovascular, and metabolic consequences that accompany obstructive sleep apnea-hypopnea (OSAH) in conjunction with the mechanistic pathways implicated in mediating these effects. Particular emphasis is placed on the association with hypertension (HTN). Varying levels of evidence support a role of OSAH in perpetuating sustained HTN, nocturnal HTN, and difficult to control HTN as well as in contributing to the occurrences of nondipping of blood pressure (BP) and increased BP variability. In this context, the emergence of matched designs, adjusted analyses, meta-analyses as well as longitudinal and interventional studies strengthens causal inferences drawn from older observational studies, which suffered from such limitations as confounding.

Cost-effectiveness of continuous positive airway pressure therapy in patients with obstructive sleep apnea-hypopnea in British Columbia

BACKGROUND

Obstructive sleep apnea-hypopnea (OSAH) is a common disorder characterized by recurrent collapse of the upper airway during sleep. Patients experience a reduced quality of life and an increased risk of motor vehicle crashes (MVCs). Continuous positive airway pressure (CPAP), which is the first-line therapy for OSAH, improves sleepiness, vigilance and quality of life.

OBJECTIVE

To assess the cost-effectiveness of CPAP therapy versus no treatment for OSAH patients who are drivers.

METHODS

A Markov decision analytical model with a five-year time horizon was used. The study population consisted of male and female patients, between 30 and 59 years of age, who were newly diagnosed with moderate to severe OSAH. The model evaluated the cost-effectiveness of CPAP therapy in reducing rates of MVCs and improving quality of life. Utility values were obtained from previously published studies. Rates of MVCs under the CPAP and no CPAP scenarios were calculated from Insurance Corporation of British Columbia data and a systematic review of published studies. MVCs, equipment and physician costs were obtained from the British Columbia Medical Association, published cost-of-illness studies and the price lists of established vendors of CPAP equipment in British Columbia. Findings were examined from the perspectives of a third-party payer and society.

RESULTS

From the third-party payer perspective, CPAP therapy was more effective but more costly than no CPAP (incremental cost-effectiveness ratio [ICER] of $3,626 per quality-adjusted life year). From the societal perspective, the ICER was similar ($2,979 per quality-adjusted life year). The ICER was most dependent on preference elicitation method used to obtain utility values, varying almost sixfold under alternative assumptions from the base-case analysis.

CONCLUSION

After considering costs and impact on quality of life, as well as the risk of MVCs in individuals with OSAH, CPAP therapy for OSAH patients is a highly efficient use of health care resources. Provincial governments who do not provide funding for CPAP therapy should reconsider.

The public health and safety consequences of sleep disorders

Sleep deprivation and medical disorders of sleep are common in today's society and have significant public health implications. In this article, we address 3 specific issues related to the public health and safety consequences of sleep disorders. First, we review data that has linked sleep restriction to a variety of adverse physiologic and long-term health outcomes including all-cause mortality, diabetes, and cardiovascular disease. Second, we will review recent data that has demonstrated that therapy for obstructive sleep apnea (the most common respiratory disorder of sleep) is an extremely efficient use of healthcare resources (in terms of dollars spent per quality adjusted life year gained), and compares favorably with other commonly funded medical therapies. Finally, we will review data that illustrate the potential adverse patient and occupational safety impacts of the extreme work schedules of housestaff (physicians in training).

Effect of continuous positive airway pressure treatment on serum cardiovascular risk factors in patients with obstructive sleep apnea-hypopnea syndrome

BACKGROUND

Serum levels of circulating markers associated with cardiovascular morbidity are elevated in patients with obstructive sleep apnea-hypopnea syndrome (OSAHS). These factors are studied in patients mainly before the application of therapy with continuous positive airway pressure (CPAP), and the effects of CPAP treatment on them have not been thoroughly studied. Therefore, the aim of the study was to examine the effect of compliance to CPAP therapy on these factors.

METHODS

Patients with newly diagnosed OSAHS, nonsmokers, without comorbidities or medication use, at baseline and during the follow-up period, were included. Serum cardiovascular risk factors (ie, high-sensitivity C-reactive protein [hs-CRP], homocysteine, total cholesterol, triglycerides, high-density lipoprotein cholesterol [HDL-C], low-density lipoprotein cholesterol, apolipoprotein A-I [ApoA-I], and apolipoprotein B [ApoB]) were measured at baseline and 6 months after CPAP application. Patients were classified into the following three groups according to CPAP use: group 1 (n = 20), good compliance (>or= 4 h use per night); group 2 (n = 19), poor compliance (< 4 h use per night); and group 3 (n = 14), refusal of CPAP treatment.

RESULTS

Fifty-three patients (47 male patients and 6 female patients; mean [+/- SD] age, 46.09 +/- 10.87 years) were included in the study. In all groups, body mass index remained stable. In group 1, significant decreases in the levels of hs-CRP (p = 0.03), homocysteine (p = 0.005), total cholesterol (p = 0.021), total cholesterol/HDL-C ratio (p = 0.018), and ApoB/ApoA-I ratio (p = 0.021) was observed. The patients in group 2 showed a decrease in homocysteine levels (p = 0.021) only, while no significant changes were observed in the patients in group 3.

CONCLUSIONS

Good compliance to CPAP treatment lowers the serum levels of cardiovascular risk factors, indicating a beneficial effect on the overall cardiovascular risk.

A multicentre trial of education strategies at CPAP induction in the treatment of severe sleep apnoea–hypopnoea syndrome

BACKGROUND AND PURPOSE

Compliance with continuous positive airway pressure (CPAP) treatment in obstructive sleep apnoea syndrome (OSAS) may be difficult. Patient education is important but strategies and their outcomes are not clear.

PATIENTS AND METHODS

We studied the effects of four education strategies on compliance and quality of life changes with CPAP treatment in seven centres in the French ANTADIR homecare network. Patients received from prescribers either a simple oral explanation (SP) or an oral and written explanation (RP) of CPAP use. In addition, they received from homecare technicians either a single home visit (SH) at CPAP onset or repeated home visits at CPAP onset and at 1 week, 1 month and 3 months after (RH). Compliance and quality of life were evaluated at CPAP onset, and at 3, 6 and 12 months after initiation of treatment.

RESULTS

One hundred twelve patients with severe OSAS (mean age 58+/-11 year, apnoea-hypopnoea index 58+/-25/h) were allocated randomly to groups (SP+SH; SP+RH; RP+SH; RP+RH) with no initial differences. Quality of life, evaluated by the generic SF-36 questionnaire, improved in the combined emotional domains. Compliance was over 5h in all four education groups. These effects were sustained over 12 months and were not different between the four groups. We conclude that standard education strategies for CPAP induction in France are sufficient for good compliance and improved quality of life with CPAP. Education with reinforced input should be focussed on identified subgroups prone to problems.

Two new tools for assessing patients' knowledge and beliefs about obstructive sleep apnea and continuous positive airway pressure therapy

BACKGROUND AND PURPOSE

Patients' knowledge and beliefs about their illnesses are known to influence a range of health related variables, including treatment compliance. It may, therefore, be important to quantify these variables to assess their impact on compliance, particularly in chronic illnesses such as Obstructive Sleep Apnea (OSA) that rely on self-administered treatments. The aim of this study was to develop two new tools, the Apnea Knowledge Test (AKT) and the Apnea Beliefs Scale (ABS), to assess illness knowledge and beliefs in OSA patients.

PATIENTS AND METHODS

The systematic test construction process followed to develop the AKT and the ABS included consultation with sleep experts and OSA patients. The psychometric properties of the AKT and ABS were then investigated in a clinical sample of 81 OSA patients and 33 healthy, non-sleep disordered adults.

RESULTS

Results suggest both measures are easily understood by OSA patients, have adequate internal consistency, and are readily accepted by patients. A preliminary investigation of the validity of these tools, conducted by comparing patient data to that of the 33 healthy adults, revealed that apnea patients knew more about OSA, had more positive attitudes towards continuous positive airway pressure (CPAP) treatment, and attributed more importance to treating sleep disturbances than non-clinical groups.

CONCLUSIONS

Overall, the results of psychometric analyses of these tests suggest these measures will be useful clinical tools with numerous beneficial applications, particularly in CPAP compliance studies and apnea education program evaluations.

Mechanical Ventilation

Mechanical ventilation is the second most frequently performed therapeutic intervention after treatment for cardiac arrhythmias in intensive care units today. Countless lives have been saved with its use despite being associated with a greater than 30% in-hospital mortality rate. As life expectancies increase and people with chronic illnesses survive longer, artificial support with mechanical ventilation is also expected to rise. In one survey, over half of senior internal medicine residents reported their training on mechanical ventilation as inadequate, whereas the majority of critical care nurses reported having received no formal education on its use. Technological advances resulting in the availability of sleeker ventilators with graphic waveform displays and new modes of ventilation have challenged the bedside clinicians to incorporate this new data along with evidenced-based research into their daily practice. A review of current thoughts on mechanical ventilation and weaning is presented.

Continuous positive airway pressure therapy in sleep apnoea

Sleep apnoea is associated with increased mortality and morbidity. The treatment goal is to reduce the neurocognitive and cardiovascular sequelae. CPAP therapy in sleep apnoea is discussed in two parts in the article. The first part will consider CPAP therapy in the more common form of sleep apnoea (i.e. obstructive or mixed sleep apnoea) and the second part will consider CPAP therapy in central sleep apnoea. Alternative positive airway pressure modalities are discussed. CPAP therapy has been extensively studied and it remains the mainstay of treatment in obstructive sleep apnoea, as it is still the most consistently efficacious and safe option. However, its major disadvantage is that it does not confer a cure to this disorder and hence therapy is generally life long with its usual treatment compliance problems. As such, there are continuous improvement strategies. The role of CPAP therapy in central sleep apnoea is more limited. There has been increasing data on the beneficial effect of CPAP on central sleep apnoea/Cheyne-Stokes respiration in congestive heart failure. Evidence for CPAP therapy in sleep apnoea has evolved significantly over the last decade. However, more research and publication of large-scale long-term randomized trials of treatment in sleep apnoea to assess patient-orientated outcomes and preferences are necessary.

Severe upper airway obstruction during sleep

Few disorders may manifest with predominantly sleep-related obstructive breathing. Obstructive sleep apnea (OSA) is a common disorder, varies in severity and is associated with significant cardiovascular and neurocognitive morbidity. It is estimated that between 8 and 18 million people in the United States have at least mild OSA. Although the exact mechanism of OSA is not well-delineated, multiple factors contribute to the development of upper airway obstruction and include anatomic, mechanical, neurologic, and inflammatory changes in the pharynx. OSA may occur concomitantly with asthma. Approximately 74% of asthmatics experience nocturnal symptoms of airflow obstruction secondary to reactive airways disease. Similar cytokine, chemokine, and histologic changes are seen in both disorders. Sleep deprivation, chronic upper airway edema, and inflammation associated with OSA may further exacerbate nocturnal asthma symptoms. Allergic rhinitis may contribute to both OSA and asthma. Continuous positive airway pressure (CPAP) is the gold standard treatment for OSA. Treatment with CPAP therapy has also been shown to improve both daytime and nighttime peak expiratory flow rates in patients with concomitant OSA and asthma. It is important for allergists to be aware of how OSA may complicate diagnosis and treatment of asthma and allergic rhinitis. A thorough sleep history and high clinical suspicion for OSA is indicated, particularly in asthma patients who are refractory to standard medication treatments.

A preliminary investigation of the effectiveness of a sleep apnea education program

OBJECTIVES

This study aimed to evaluate a standardised sleep apnea patient education program and develop a study design that may be used to evaluate other such education programs.

METHOD

Thirty-four adults diagnosed with obstructive sleep apnea hypopnea syndrome (OSAHS) underwent a standard sleep apnea education program and completed measures of knowledge of and beliefs about sleep apnea before, after, and 3 months following education. Two outcome measures were used: the Apnea Knowledge Test (AKT) and the Apnea Beliefs Scale (ABS).

RESULTS

AKT results showed significant knowledge gains posteducation, which were maintained at follow-up. Patients also reported more positive beliefs about their ability to change their behaviour and comply with continuous positive airway pressure (CPAP) treatment recommendations after education.

DISCUSSION

Findings from this preliminary investigation suggest that the education program used in this study may improve patients' knowledge of CPAP and promote functional beliefs about OSAHS treatment. This program clearly warrants further research, and ultimately such programs may prove important in improving CPAP compliance.

Obesity and obstructive sleep apnea

There is a very high prevalence of OSA in obese individuals and a high prevalence of obesity in patients with OSA. The pathophysiology of OSA is intimately linked to obesity. Anatomic and functional considerations of the pharyngeal airway, the CNS, central obesity, and leptin likely interact in the development of OSA in obese individuals. OSA may itself predispose individuals to worsening obesity because of sleep deprivation, daytime somnolence, and disrupted metabolism. The diagnosis of OSA requires the clinician's awareness of its potential to cause a spectrum of acute and chronic neurocognitive, psychiatric, and nonspecific symptoms in patients who may be unaware that their sleep is disturbed. Symptoms and examination findings help predict which obese individuals have OSA, and polysomnography is the gold standard by which to make the diagnosis and assess the effects of treatment. Numerous disease states are associated with both OSA and obesity, and it is becoming clear that the relationships are mediated by complex interrelated mechanisms. Common diseases and disease mechanisms in OSA and obesity suggest that conditions related to obesity may be better managed if patients, particularly those who are morbidly obese, are evaluated and treated for previously undiagnosed OSA. OSA is cured in only specific cases with craniofacial or upper airway surgery, and the general application of UVP is not efficacious. OSA also can be cured with sufficient lifestyle-mediated or surgical weight loss; however, in the absence of long-term weight maintenance, OSA returns with weight gain. Although not curative, nasal CPAP is the initial treatment of choice for most patients because of its noninvasive approach and technical efficacy. It is limited, however, by patient acceptance and long-term compliance. Advances in mask comfort and use of humidified air should increase its acceptance. Future management strategies include newer generations of positive airway devices that automatically titrate pressures (which are not yet recommended by expert organizations) and multidisciplinary approaches to managing the care of patients with OSA.