Impact of continuous positive airway pressure on vascular endothelial growth factor in patients with obstructive sleep apnea: a meta-analysis

Purpose

Cumulative evidence supports the clear relationship of obstructive sleep apnea (OSA) with cardiovascular disease (CVD). And, adherence to continuous positive airway pressure (CPAP) treatment alleviates the risk of CVD in subjects with OSA. Vascular endothelial growth factor (VEGF), a potent angiogenic cytokine regulated by hypoxia-inducible factor, stimulates the progression of CVD. Thus, whether treatment with CPAP can actually decrease VEGF in patients with OSA remains inconclusive. The purpose of the present study was to quantitatively evaluate the impact of CPAP therapy on VEGF levels in OSA patients.

Methods

We systematically searched Web of Science, Cochrane Library, PubMed, and Embase databases that examined the impact of CPAP on VEGF levels in OSA patients prior to May 1, 2017. Related searching terms were “sleep apnea, obstructive,” “sleep disordered breathing,” “continuous positive airway pressure,” “positive airway pressure,” and “vascular endothelial growth factor.” We used standardized mean difference (SMD) to analyze the summary estimates for CPAP therapy.

Results

Six studies involving 392 patients were eligible for the meta-analysis. Meta-analysis of the pooled effect showed that levels of VEGF were significantly decreased in patients with OSA before and after CPAP treatment (SMD?=???0.440, 95% confidence interval (CI)?=???0.684 to ??0.196, z?=?3.53, p?=?0.000). Further, results demonstrated that differences in age, body mass index, apnea–hypopnea index, CPAP therapy duration, sample size, and racial differences also affected CPAP efficacy.

Conclusions

Improved endothelial function measured by VEGF may be associated with CPAP therapy in OSA patients. The use of VEGF levels may be clinically important in evaluating CVD for OSA patients. Further large-scale, well-designed long-term interventional investigations are needed to clarify this issue.

     

Continuous positive airway pressure device-based automated detection of obstructive sleep apnea compared to standard laboratory polysomnography

Purpose

Obstructive sleep apnea (OSA) is a common health problem that affects more than 2–4% of the US population. Polysomnography (PSG) is the gold standard for diagnosing OSA. PSG is, however, expensive, time-consuming, and not always readily accessible. Hence, alternative diagnostic methods such as home-based testing have been evaluated. We studied the ability of the REMstar Pro (RSP2, a brand of continuous positive airway pressure (CPAP) device) to identify abnormal breathing events in subjects with OSA and compared this with breathing events simultaneously determined by laboratory-based PSG.

Methods

We evaluated 10 subjects previously diagnosed with OSA (apnea hypopnea index (AHI)?>?15, known therapeutic level of CPAP). Subjects underwent attended PSG using the REMstar Pro M series machine and their prescribed interface/mask type. The first 3 h of the study were conducted using a subtherapeutic CPAP (4 cm H2O). The last 3 h or remaining portion of the PSG was completed using the previously determined therapeutic CPAP. Comparison of respiratory events detected by PSG vs the RSP2 was performed.

Results

Subjects included four men and six women, aged 32 to 57 years and with a body mass index ranging from 29.5–66.4. The baseline AHI ranged from 18.3–93.1, with the AHI at therapeutic CPAP ranging from 0–3. Apnea counts at baseline and at therapeutic CPAP by manually scored PSG and REMstar were not significantly different (mean at subtherapeutic 11.7 vs 12.5, p?=?0.76; median at therapeutic CPAP 2.0 vs 4.5, p?=?0.15). Hypopnea counts at baseline and at effective CPAP by PSG and REMstar were not significantly different (mean at subtherapeutic 38.1 vs. 40.9, p?=?0.72; median at therapeutic CPAP 5.0 vs. 2.5, p?=?0.34). The correlation coefficient of REMstar and PSG for apnea and hypopnea was significant in subtherapeutic phase only (apnea r?=?0.78, p?=?0.007; hypopnea r?=?0.76, p?=?0.01). Agreement between the two methods declined for hypopnea detection at therapeutic CPAP.

Conclusions

The monitoring of residual sleep-disordered breathing on treatment, in addition to adherence, is an important objective therapeutic target in OSA. The REMstar Pro detects sleep-disordered breathing events similar to that of a manually scored PSG—for apnea but not for hypopnea—and merits further investigation as a device to determine disease severity and treatment efficacy.     

The effect of continuous positive airway pressure therapy on blood pressure and arterial stiffness in hypertensive patients with obstructive sleep apnea

Aim

We aimed to evaluate the effect of continuous positive airway pressure (CPAP) therapy on blood pressure (BP) and arterial stiffness in hypertensive patients with obstructive sleep apnea (OSA).

Patients and methods

We studied 38 hypertensive patients who suffered from severe OSA. Ambulatory BP measurement was performed at baseline and after at least 3 months of uninterrupted CPAP therapy. In 19 of these patients, we also measured pulse wave velocity (PWV) at baseline, after the first night of CPAP therapy and at 3 months. Fifteen normotensive subjects without OSA comprised the control group.

Results

CPAP therapy reduced systolic BP from 141.5?±?12.1 to 133.5?±?9.7 mmHg (p?=?0.007) and diastolic BP from 87.8?±?6.8 to 83?±?5.4 mmHg (p?=?0.004). CPAP also reduced the PWV from 8.81?±?1.4 to 8.18?±?1 m/s after the first night of CPAP therapy (p?=?0.003) and to 7.37?±?1 m/s at 3 months (p?=?0.007).

Conclusions

To the best of our knowledge, this is the first study demonstrating that CPAP therapy in hypertensive patients with OSA improves arterial stiffness from the first night and that this favorable effect is maintained for at least 3 months of CPAP use. A reduction in BP was also observed, even though BP control was not always achieved.     

Determinants of continuous positive airway pressure adherence in a sleep clinic cohort of South Florida Hispanic veterans

Purpose

There are little existing data on continuous positive airway pressure (CPAP) adherence in US Hispanic veterans with obstructive sleep apnea (OSA). Our aim was to describe determinants of 1-month adherence in a sleep clinic cohort of South Florida Hispanic veterans.

Methods

Hispanic veterans referred to the Miami VA sleep clinic were recruited and completed questionnaires about sleep apnea risk, sleep quality, insomnia symptoms, sleepiness, depression/anxiety, acculturation, personality traits, and cognitions about OSA and CPAP. Individuals at risk for OSA were scheduled for baseline polysomnography (PSG), followed by in-lab CPAP titration or a trial of auto-CPAP. Participants with OSA accepting CPAP therapy were asked to return after 7 and 30 days of treatment for adherence verification and to repeat questionnaires.

Results

One hundred twenty-four participants (94 % men) were enrolled with 114 completing overnight PSG. Eighty-six out of 95 participants (91 %) with sleep apnea syndrome or moderate to severe OSA accepted CPAP treatment. Fifty-nine participants completed both follow-up visits with a mean CPAP use at 30 days of 3.6?±?2.0 h. The only independent predictor of 7-day mean daily CPAP use was the baseline Insomnia Severity Index while the best predictor of 30-day mean daily CPAP use was the 7-day mean daily use.

Conclusions

Our study suggests that South Florida Hispanic veterans with OSA evaluated in a sleep clinic show poor CPAP adherence. Insomnia and poor early use predicted poor adherence overall. Larger prospective studies with other race–ethnic groups are needed to determine the role of ethnicity and race in CPAP adherence among US veterans with OSA.     

Impact of continuous positive airway pressure on C-reactive protein in patients with obstructive sleep apnea: a meta-analysis

Purpose

C-reactive protein (CRP) is associated with the development of obstructive sleep apnea (OSA) and cardiovascular diseases. Continuous positive airway pressure (CPAP) is an effective treatment for OSA, but the impact of CPAP therapy on CRP levels in patients with OSA remains unclear. To obtain this information, we performed a meta-analysis to determine whether effective CPAP therapy could reduce serum CRP levels.

Methods

A comprehensive literature search was performed to identify studies that examined the impact of CPAP on serum CRP levels in OSA patients who were treated with CPAP for at least 4 weeks. Standardized mean difference (SMD) was used to analyze the summary estimates for CPAP therapy.

Results

Fourteen self-control design studies involving 1199 patients with OSA met the inclusion criteria. Meta-analysis indicated that the overall SMD for the CRP levels was 0.64 units (95 % confidence interval (CI) 0.40 to 0.88) before and after CPAP therapy; test for overall effect z?=?5.27 (P?=?0.000). Subgroup analysis showed that evolution of CRP decreased non-significantly in less than 3 months (SMD, 0.26, 95 % CI ?0.08 to 0.60, P?=?0.138), significantly decreased after 3 months (SMD, 0.68, 95 % CI 0.34 to 1.02, P?=?0.000), and further declined after 6 months (SMD, 0.74, 95 % CI 0.43 to 1.05, P?=?0.000).

Conclusions

The systemic inflammation, as measured by CRP, was present and significantly reduced by effective CPAP therapy in patients with OSA. The use of CRP levels may be clinically recognized as a valuable predictor for OSA treatment monitoring.     

Effect of continuous positive airway pressure on regional cerebral blood flow during wakefulness in obstructive sleep apnea

Background

The alteration of regional cerebral blood flow (rCBF) during wakefulness after the treatment for obstructive sleep apnea syndrome (OSA) using continuous positive airway pressure (CPAP) has not been elucidated. The aim of this study was to investigate rCBF characteristics and the effects of nasal CPAP in OSA patients.

Methods

Fifteen severe OSA patients (apnea–hypopnea index, 62.7?±?22.4/h), when awake, underwent Technetium-99m ethyl cysteinate dimer single photon emission computed tomography before and after CPAP treatment, and the findings were compared to those of nine healthy controls matched for age and sex.

Results

Compared to controls, patients with OSA before CPAP treatment showed a significantly lower rCBF in the frontal lobe. After the treatment, no difference in rCBF was observed between the good CPAP compliance group and the controls. In the former group, there was a positive correlation between the 3 % oxygen desaturation index on diagnostic polysomnogram and the increase of rCBF after CPAP treatment in the frontal lobe.

Conclusions

When awake, patients with severe OSA were shown to have reversible decreases in rCBF, especially in the frontal lobe, and an appropriate CPAP treatment was thought to improve rCBF in this area. Our results support the importance of appropriate CPAP treatment for severe OSA patients.     

The acute effects of continuous positive airway pressure and oxygen administration on blood pressure during obstructive sleep apnea.

We have measured blood pressure continuously with a digital artery blood pressure monitor in eight patients with severe obstructive sleep apnea (OSA) during 30 min each of wakefulness, OSA, OSA with added oxygen to keep saturation above 96 percent at all times (OSA+O2), and nasal continuous positive airway pressure (CPAP) therapy. Mean blood pressures were not different between wakefulness, OSA, OSA+O2, and CPAP, although the variability in blood pressure was significantly greater during OSA and OSA+O2 than during wakefulness and CPAP. The addition of oxygen did not attenuate the variability in blood pressure. Using multiple linear regression modeling to further dissect out the principal variables determining the postapneic blood pressure rise, we found that only apnea length (r2 = 0.28, p less than 0.0001) and pulse rate changes (r2 = 0.15, p less than 0.0001) remained significantly related to SBPmax, while hypoxemia did not. We found the same trends in the other variables SBPten, DBPmax, and DBPten. Hypoxemia made a small contribution to the size of DBPmax, although this was small by comparison with apnea length. We conclude that CPAP treatment of OSA does not lower mean blood pressure acutely, although it significantly reduces the large oscillations in blood pressure seen in patients with untreated OSA. The rise in blood pressure following each apnea is not primarily due to arterial desaturation but is related to apnea length and may be caused by increased sympathetic activity secondary to arousal.     

Effects of treatment with oral appliance on 24-h blood pressure in patients with obstructive sleep apnea and hypertension: a randomized clinical trial

Background

Continuous positive airway pressure treatment has been shown to lower blood pressure (BP) in patients with obstructive sleep apnea (OSA). The aims of the present pilot study were to evaluate the potential effects of oral appliance (OA) therapy on BP, to assess various outcome BP measures, and to inform sample size calculation.

Methods

Seventy-two patients with OSA and hypertension were randomly assigned to intervention with either an OA with mandibular advancement (active group) or an OA without advancement (control group). Before and after 3 months of treatment, the patients underwent nocturnal somnographic registration and 24-h ambulatory BP monitoring.

Results

Among the various BP measures, the largest trend toward effect of OA treatment was seen in 24-h mean systolic BP with a 1.8 mmHg stronger BP reduction in the active group compared with controls. A stronger trend toward effect was seen in a subgroup with baseline ambulatory daytime mean systolic BP >135/85 mmHg where the mean systolic BP fell, on average, 2.6 mmHg. Additional exclusion of patients with baseline apnea hypopnea index (AHI) ≤15 gave a significant reduction in mean systolic BP of 4.4 mmHg (P?=?0.044) in the active group compared with controls.

Conclusions

In patients with OSA and hypertension, OA treatment had a modest trend toward effect on reducing BP. A stronger trend toward treatment effect was seen after excluding patients with normal baseline ambulatory BP. Additional exclusion of patients with baseline AHI ≤15 showed a significant treatment effect. Data to inform sample size for an adequately powered randomized study are provided.     

Continuous positive airway pressure therapy for treating sleepiness in a diverse population with obstructive sleep apnea: results of a meta-analysis

BACKGROUND: Although continuous positive airway pressure (CPAP) has become the standard of care in the treatment of obstructive sleep apnea (OSA), 2 systematic reviews have questioned its utility. Since the publication of these reviews, several randomized controlled trials have been reported. We, therefore, performed a meta-analysis to assess the effect of CPAP on subjective and objective sleepiness. METHODS: We conducted a thorough literature search to identify all published randomized controlled trials of CPAP in patients with OSA. Meta-analyses were performed using a random-effects model. Statistical heterogeneity was assessed using the Q statistic. RESULTS: Twelve trials of CPAP in patients with OSA meeting our inclusion criteria were found. The Epworth Sleepiness Scale score was reported in 11 studies (706 patients). A meta-analysis found that CPAP reduced the Epworth Sleepiness Scale score an average of 2.94 points more than placebo (P<.001). The heterogeneity (Q10 = 57.7, P<.001) between studies could not be explained by differences in sex composition, mean age, mean body mass index, or country of study. Trials recruiting subjects with severe OSA plus sleepiness (mean apnea-hypopnea index, > or =30 events per hour; and mean Epworth Sleepiness Scale score, > or =11) had a greater decrease in the Epworth Sleepiness Scale score than the other studies (4.75 vs 1.10; P<.001). Objective measures of sleepiness were reported in 8 trials (482 subjects). Continuous positive airway pressure increased sleep onset latency by 0.93 minute (P =.04) more than placebo. CONCLUSIONS: Continuous positive airway pressure therapy significantly improves subjective and objective measures of sleepiness in patients with OSA across a diverse range of populations. Patients with more severe apnea and sleepiness seem to benefit the most.     

Association between continuous positive airway pressure and changes in serum leptin in patients with obstructive sleep apnoea: a meta-analysis

Purpose

The role of leptin in the development of obstructive sleep apnoea (OSA) has been identified. However, the effects of OSA treatment using continuous positive airway pressure (CPAP) on serum leptin levels remain controversial. To address this issue, a meta-analysis was conducted to evaluate the effects of CPAP therapy on serum leptin levels in OSA.

Methods

A comprehensive literature search was performed to identify studies that focused on the effects of CPAP therapy (treatment duration, ≥4 weeks) on the serum leptin levels of OSA patients. Standardised mean difference (SMD) was used to analyse the summary estimates for CPAP therapy.

Results

Fifteen studies involving 427 patients were included in the meta-analysis. Results indicate that the overall SMD of the leptin levels before and after CPAP therapy was 0.137 (95 % confidence interval (CI) 0.002 to 0.272); test for overall effect z?=?1.99 (P?=?0.046). Sources of heterogeneity were not found by subgroup and meta-regression analyses. Subgroup analyses showed that differences in OSA severity, baseline body mass index, compliance, CPAP duration and leptin assay did not affect the effectiveness of CPAP therapy.

Conclusions

The evidence for the use of CPAP therapy on decrease of leptin levels in OSA patients is low, and stronger evidence is needed.     

An electrocardiogram-based analysis evaluating sleep quality in patients with obstructive sleep apnea

Objective

The study compares polysomnography (PSG) and cardiopulmonary coupling (CPC) sleep quality variables in patients with (1) obstructive sleep apnea (OSA) and (2) successful and unsuccessful continuous positive airway pressure (CPAP) response.

Patients/methods

PSGs from 50 subjects (32 F/18 M; mean age 48.4?±?12.29 years; BMI 34.28?±?9.33) were evaluated. OSA patients were grouped by no (n?=?16), mild (n?=?13), and moderate to severe (n?=?20) OSA (apnea–hypopnea index (AHI)?≤?5, >5–15, >15 events/h, respectively). Outcome sleep quality variables were sleep stages in non-rapid eye movement, rapid eye movement sleep, and high (HFC), low (LFC), very low-frequency coupling (VLFC), and elevated LFC broad band (e-LFC_BB). An AHI?≤?5 events/h and HFC?≥?50 % indicated a successful CPAP response. CPC analysis extracts heart rate variability and QRS amplitude change that corresponds to respiration. CPC-generated spectrograms represent sleep dynamics from calculated coherence product and cross-power of both time series datasets.

Results

T tests differentiated no and moderate to severe OSA groups by REM % (p?=?0.003), HFC (p?=?0.007), VLFC (p?=?0.007), and LFC/HFC ratio (p?=?0.038) variables. The successful CPAP therapy group (n?=?16) had more HFC (p?=?0.003), less LFC (p?=?0.003), and e-LFC_BB (p?=?0.029) compared to the unsuccessful CPAP therapy group (n?=?8). PSG sleep quality measures, except the higher arousal index (p?=?0.038) in the unsuccessful CPAP group, did not differ between the successful and unsuccessful CPAP groups. HFC?≥?50 % showed high sensitivity (77.8 %) and specificity (88.9 %) in identifying successful CPAP therapy.

Conclusions

PSG and CPC measures differentiated no from moderate to severe OSA groups and HFC?≥?50 % discriminated successful from unsuccessful CPAP therapy. The HFC?≥?50 % cutoff showed clinical value in identifying sleep quality disturbance among CPAP users.     

The effects of continuous positive airway pressure therapy on mean platelet volume in patients with obstructive sleep apnea

Previous studies have reported increased platelet activation and aggregation in patients with obstructive sleep apnea (OSA). Continuous positive airway pressure (CPAP) treatment has been shown to decrease platelet activation. We aimed to study the effects of nasal CPAP therapy has on MPV values in patients with severe OSA. Thirty-one patients (21 men; mean age 53.8?±?9.2 years) with severe OSA (AHI?>?30 events/hour) constituted the study group. An age, gender and body mass index (BMI) matched control group was composed 25 subjects (14 men; mean age 49.6?±?8.5 years) without OSA (AHI?<?5 events/hour). We measured MPV values in patients with severe OSA and control subjects and we measured MPV values after 6 months of CPAP therapy in severe OS patients. The median (IQR) MPV values were significantly higher in patients with severe OSA than in control group (8.5 [8.3–9.1] vs. 8.3 [7.5–8.8] fL; p?=?0.03). The platelet counts were significantly lower in patients with severe OSA than in control group (217.8?±?45.9 vs. 265.4?±?64.0?×?10⁹/L; p?=?0.002). The six months of CPAP therapy caused significant reductions in median (IQR) MPV values in patients with severe OSA (8.5 [8.3–9.1] to 7.9 [7.4–8.2] fL; p?<?0.001). Six months of CPAP therapy caused significant increase in platelet counts when compared with baseline values (217.8?±?45.9 to 233.7?±?60.6?×?10⁹/L; p?<?0.001). We have found that the MPV values of patients with severe OSA were significantly higher than those of the control subjects and 6 months CPAP therapy caused significant reductions in the MPV values in patients with severe OSA.     

Effects of continuous positive airway pressure versus supplemental oxygen on 24-hour ambulatory blood pressure

Obstructive sleep apnea (OSA) is associated with recurrent episodes of nocturnal hypoxia and increased risk for development of systemic hypertension. Prior studies have been limited, however, in their ability to show reduction in blood pressure after continuous positive airway pressure (CPAP) therapy, and the effect of supplemental oxygen alone on blood pressure in OSA has not been evaluated. We performed a randomized, double-blind, placebo-controlled study comparing the effects of 2 weeks of CPAP versus sham-CPAP versus supplemental nocturnal oxygen on 24-hour ambulatory blood pressure in 46 patients with moderate-severe OSA. We found that 2 weeks of CPAP therapy resulted in a significant reduction in daytime mean arterial and diastolic blood pressure and nighttime systolic, mean, and diastolic blood pressure (all Ps <0.05). Although nocturnal supplemental oxygen therapy improved oxyhemoglobin saturation, it did not affect blood pressure. We conclude that CPAP therapy reduces both daytime and nighttime blood pressure in patients with OSA, perhaps through mechanisms other than improvement of nocturnal oxyhemoglobin saturation.     

Effects of CPAP and mandibular advancement device treatment in obstructive sleep apnea patients: a systematic review and meta-analysis

The purpose of this review is to conduct a systematic review and meta-analysis comparing the effects of continuous positive airway pressure (CPAP) with a mandibular advancement device (MAD) in improving the quality of life (sleepiness, cognitive, and functional outcomes) in patients diagnosed with obstructive sleep apnea (OSA). Authors identified randomized, placebo-controlled studies from MEDLINE through PubMed, Web of Science, and the Cochrane Library. Studies were assessed for inclusion and exclusion criteria, as well as risk of bias. Initial search yielded 240 unduplicated references, which the authors reduced to 12 relevant studies. Patients with CPAP therapy showed no statistically significant difference in the post-treatment quality of life measured with the SF-36 mental health component (p = .994), or the SF-36 physical functioning component (p = .827). There was no significant improvement in neither Functional Outcomes of Sleep Questionnaire (p = .788) nor cognitive performance (p = .395) compared to patients treated with oral appliances. However, the meta-analyses’ overall results showed a significant improvement in the post-treatment apnea–hypopnea index (AHI) in favor of CPAP therapy as compared with the oral appliance group (p < .001). Meta-analyses showed unclear results for sleepiness with no significant differences in average post-treatment Epworth Sleepiness Scale [ESS] (p = .203), but significant differences in change in ESS from baseline favorable to CPAP treatment (p = .047). Further studies are needed. Compliance with treatment was 1.1 h per night significantly lower with CPAP than MAD (p = .004), which could explain why though efficacy (AHI) is better with CPAP, no significant results are shown for quality of life, cognitive, and functional outcomes. Though CPAP is significantly more efficient in reducing AHI (moderate quality of evidence), it has a significantly lower compliance resulting in no differences with MAD in quality of life, cognitive, or functional outcomes. Sleep medicine professionals should monitor treatment compliance and offer patients non-compliant with CPAP an oral appliance for treatment of OSA.     

Survival Benefit of CPAP Favors Hypercapnic Patients with the Overlap Syndrome

Background

Patients with the combination of chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea (OSA), known as the “overlap syndrome,” have a substantially greater risk of morbidity and mortality compared to those with either COPD or OSA alone. The study’s objective was to report on the long-term outcome of hypercapnic (PaCO₂ ≥ 45 mmHg) and normocapnic patients with the overlap syndrome treated with continuous positive airway pressure (CPAP).

Methods

A nonconcurrent cohort of consecutive patients with the overlap syndrome was followed for a median duration of 71 months (range 1–100) at a VA sleep center. All patients were managed according to the prevailing recommendations of both diseases. The end point of the study was all-cause mortality.

Results

Of the 271 patients identified, 104 were hypercapnic (PaCO₂ = 51.6 ± 4.3 mmHg). Both normocapnic and hypercapnic patients had comparable apnea–hypopnea indexes (AHI) (29.2 ± 23.8 and 35.2 ± 29.2/h, respectively; p = 0.07) and similar adherence rates to CPAP (43 and 42 %, respectively, p = 0.9). Survival analysis revealed that hypercapnic patients who were adherent to CPAP had reduced mortality compared to nonadherent hypercapnic patients (p = 0.04). In contrast, the cumulative mortality rate for normocapnic patients was not significantly different between the adherent and the nonadherent group (p = 0.42). In multivariate analysis, the comorbidity index was the only independent predictor of mortality in normocapnic patients with the overlap syndrome [hazard ratio (HR) 1.68; p < 0.001] while CPAP adherence was associated with improved survival (HR 0.65; p = 0.04).

Conclusions

CPAP mitigates the excess risk of mortality in hypercapnic patients but not in normocapnic patients with the overlap syndrome.     

Pulmonary hypertension in obstructive sleep apnoea: effects of continuous positive airway pressure: a randomized, controlled cross-over study.

AIMS: We tested the hypothesis that: (i) obstructive sleep apnoea (OSA) by itself originates pulmonary hypertension (PH); and (ii) the application of continuous positive airway pressure (CPAP) can reduce pulmonary pressure. METHODS AND RESULTS: In this randomized and cross-over trial, 23 middle-aged OSA (apnoea-hypopnoea index, 44.1 +/- 29.3 h(-1)) and otherwise healthy patients and 10 control subjects were included. OSA patients randomly received either sham or effective CPAP for 12 weeks. Echocardiographic parameters, blood pressure recordings, and urinary catecholamine levels were obtained at baseline and after both treatment modalities. At baseline, OSA patients had higher pulmonary artery systolic pressure than control subjects (29.8 +/- 8.8 vs. 23.4 +/- 4.1 mmHg, respectively, P = 0.036). Ten out of 23 patients [43%, (95% CI: 23-64%)] and none of the control subjects had PH at baseline (P = 0.012). Two patients were removed from the study because of inadequate CPAP compliance. Effective CPAP induced a significant reduction in the values for pulmonary systolic pressure (from 28.9 +/- 8.6 to 24.0 +/- 5.8 mmHg, P < 0.0001). The reduction was greatest in patients with either PH or left ventricular diastolic dysfunction at baseline. CONCLUSION: Severe OSA is independently associated with PH in direct relationship with disease severity and presence of diastolic dysfunction. Application of CPAP reduces pulmonary systolic pressure levels.     

Long-term adherence to ambulatory initiated continuous positive airway pressure in non-syndromic OSA children

Purpose

In children, the usual indications for continuous positive airway pressure (CPAP) are residual OSA after adenotonsillectomy and/or persistent OSA due to obesity. Data concerning adherence (hours/night) following ambulatory CPAP initiation are scarce.

Methods

An observational cohort of 78 children was followed over 2 years. All exhibited sleep-disordered breathing (SDB) symptoms, were assessed by polysomnography, and prescribed CPAP. CPAP was initiated at hospital for 10 children.

Results

OSA children, mean age 10.4?±?3.2 years, were mostly males (75.6%), with a mean body mass index of 21.2?±?7.3 kg/m², and mean apnea+hypopnea index of 12.2?±?10.6 events/hour. Seventy-two children were still on CPAP at 3 months, 63 at 6 months, 55 at 1 year, and 34 at 2 years. CPAP was discontinued thanks to rehabilitation programs, dento-facial orthopedics, and/or weight loss. Mean CPAP adherence at 1, 3, 6, 12, and 24 months was respectively 6.1?±?2.8, 6.2?±?2.6, 6.2?±?2.8, 6.3?±?2.8, and 7.0?±?2.7 h/night. There was a trend towards higher CPAP adherence and younger age, primary versus middle/high school attendance, higher baseline apnea+hypopnea index, and neurocognitive disorders.

Conclusion

In our population, mean CPAP adherence defined in hours per night was high and did not decrease during the 24-month follow-up. These findings support the feasibility of ambulatory CPAP initiation in non-syndromic OSA. The high CPAP adherence is expected to be associated with improvements in neurocognition, and in metabolic and cardiovascular parameters.

     

Postoperative complications in obstructive sleep apnea

Study objectives

This study was conducted to determine whether postoperative complications are increased in patients with obstructive sleep apnea (OSA) and to study the impact of the severity of OSA and preoperative use of continuous positive airway pressure (CPAP) on the postoperative outcome.

Design and setting

This study is retrospective in nature and was undertaken at the VA Medical Center.

Participants and methods

Three hundred seventy patients who had undergone both a major surgical procedure and a sleep study from 2000 to 2010 were identified. Patients were divided into four groups: OSA negative (apnea–hypopnea index (AHI)?<?5/h), OSA positive; mild: AHI 5 to <15/h; moderate: AHI 15 to <30/h; and severe: AHI?≥?30/h. No intervention was made during the course of the study. Postoperative complications namely respiratory, cardiac, neurological, and unplanned intensive care unit transfers were collected.

Results

There were 284 (76.8 %) patients having OSA and 86 (23.2 %) without OSA. The overall incidence of total complications was significantly higher in the OSA patients compared with the control patients (48.9 vs. 31.4 %; odds ratio 2.09, 95 % CI 1.25–3.49). There was no significant difference in total complications between those using and not using CPAP prior to hospitalization. Patients with sleep apnea had a higher incidence of respiratory complications compared to patients without sleep apnea (40.4 vs. 23.2 %; odds ratio 2.24, 95 % CI 1.29–3.90). There was no significant difference in major cardiac complications in the OSA patients compared with the control patients (13.0 vs. 9.3 %; odds ratio 1.46, 95 % CI 0.65–3.26).

Conclusion

OSA is associated with a significantly increased rate of postoperative complications.     

Long-term compliance with nasal continuous positive airway pressure therapy of obstructive sleep apnea

In an attempt to identify predictors of long-term compliance with nasal continuous positive airway pressure (CPAP), we reviewed the records of 125 patients with obstructive sleep apnea (OSA) referred to our center for nasal CPAP trials. Severity of sleep apnea, sleep staging, daytime hypersomnolence, effectiveness of nasal CPAP, previous palatal surgery, and adverse reactions were compared in compliant and noncompliant patients. Nineteen patients did not tolerate a nasal CPAP trial in the laboratory or refused home nasal CPAP therapy. Ten patients were unavailable for follow-up. Of the remaining 96 patients, 23 (24 percent) had discontinued therapy, while 73 (76 percent) were still using nasal CPAP at 14.5 +/- 10.7 months (mean +/- SD). There were no statistically significant differences between the compliant and noncompliant patients in baseline apnea plus hypopnea index (AHI), baseline sleep staging, AHI while receiving nasal CPAP, sleep staging while receiving nasal CPAP, or frequency of adverse reactions during therapy. Severe daytime sleepiness was present in 65 of the 73 compliant patients and in 12 of the 23 noncompliant patients (p less than 0.05). Ten of 43 in the compliant group had previous palatal surgery compared with ten of 23 noncompliant patients (p less than 0.05). Our data confirm earlier observations in smaller samples that compliant and noncompliant patients have equally severe sleep apnea and good initial responses to nasal CPAP. Long-term compliance with nasal CPAP may be associated with the severity of daytime hypersomnolence on presentation. Previous palatal surgery was more frequent in patients who did not tolerate long-term nasal CPAP therapy.     

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

Background

Studies show that the therapeutic CPAP pressure is associated with oral appliance (OA) treatment outcome in obstructive sleep apnea (OSA) patients. However, these studies included either CPAP adherent patients using fixed pressure devices, or partly CPAP non-adherent patients using fixed pressure or auto-adjusting (auto-CPAP) devices. In many countries, auto-CPAP is predominately used, and only those non-adherent to therapy need a change to OA. Therefore, studies examining the relationship between CPAP pressures and OA treatment outcome should focus on patients non-adherent to auto-CPAP.

Purpose

The purpose of this paper is to assess if CPAP pressures predicted OA treatment outcome in patients non-adherent to auto-CPAP therapy.

Methods

The OA treatment responders and non-responders were defined by two success criteria ((1) AHI < 5; (2) 5 ≤ AHI < 10 and > 50% AHI reduction). Logistic regression analyses were performed for CPAP pressures and baseline variables. ROC curve analyses were used to identify CPAP pressure cutoff values, alone and combined with other explanatory variables, predicting the OA treatment outcome.

Results

Eighty-seven patients with moderate or severe OSA were included. Maximum CPAP pressures (CPAPmax) were higher in non-responders by both criteria and were, together with baseline AHI, associated with the OA treatment outcome in multivariate regression analyses. ROC curves identified an optimal CPAPmax cutoff of 12 cm H₂O, corresponding to a positive predictive value (PPV) of 0.85 in predicting non-response using criterion 1. A prediction model combining CPAPmax > 12 and baseline AHI ≥ 30 had a PPV of 1.0 for non-response by both criteria.

Conclusions

Maximum CPAP pressure was a moderate predictor of OA treatment outcome, but combined with baseline AHI, the ability to identify OA non-responders was high.