Long-term nasal CPAP does not ameliorate obstructive sleep apnoea

Fifty-seven patients with obstructive sleep apnoea (OSA) were treated for at least six months with nasal continuous positive airway pressure (CPAP). At follow-up, sleep studies were performed in which CPAP was not used for the first half of the night. We compared the severity of OSA at follow-up without CPAP to the severity of OSA during the patient's initial diagnostic study. Apnoea and hypopnoea index (AHI) fell from 41.4 ± 7.5 (mean ±95% CI) to 34.8 ± 7.9 (p= 0.06 by Wilcoxon test) and minimum oxygen saturation rose from 71.6 ± 3.2 to 78.5 ± 2.6 (p<0.001). Some of this change may have been due to reduced REM sleep in the follow-up study (10.5±2.1% Total Sleep Time vs 7.4±2.4% TST, p<0.05). Long-term nasal CPAP was not associated with any reduction of obesity (BMI before CPAP 31.9 ± 1.0, after CPAP 31.7 ± 1.0 (p= 0.39). Systolic arterial pressure fell (before CPAP 143.0 ±4.5 mmHg, after CPAP 136.3 ± 4.6, p < 0.05) but diastolic pressure did not (before CPAP 88.5 ± 3.0 mmHg, after CPAP 85.6 ±2.9 mmHg, p = 0.11). We concluded that the effect of CPAP treatment for six or more months was a small fall in AHI and a small rise in minimum Sa0₂, but that this would be of marginal clinical significance, and may be artefactual. (Aust NZ J Med 1991; 21: 235–238.)     

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.     

Lack of Benefit of Continuous Positive Airway Pressure on Lung Function in Patients with Overlap Syndrome

Obstructive sleep apnea (OSA) has been shown to be an inflammatory stimulus and may potentially result in a deterioration in the respiratory status of patients with coexistent chronic obstructive pulmonary disease (COPD) (overlap syndrome). We hypothesized that with treatment of OSA, there would be an improvement in coexistent COPD in overlap patients. We also sought to characterize overlap patients by comparing them with patients with either OSA or COPD alone. We performed a retrospective study of patients who attended a university-affiliated Veterans Affairs hospital. Demographic and clinical data were obtained from the medical charts and pharmacy records for the preceding two years and for the two years following the initiation of continuous positive airway pressure (CPAP) therapy. Overlap patients had moderately severe sleep apnea (AHI 28.6 ± 4.2) and moderately severe COPD (FEV₁= 1.94 ± 0.10 L). The prevalence of overlap syndrome in COPD patients was 11.9%, and 41% in OSA patients. Overlap patients who were compliant with CPAP therapy experienced a greater decrease in FEV₁, percent predicted FEV₁, percent decrease in FEV₁, FVC, percent predicted FVC, and percent decrease in FVC when compared with noncompliant patients. A very strong correlation was found between the average hours of CPAP use per day and the percent decrease in FEV₁ (r = 0.69, p = 0.003). There was a similar strong correlation for the decrease in FEV₁ and percent predicted FEV₁. OSA is common in COPD patients; similarly, COPD is common in OSA patients. Treatment of OSA with CPAP therapy in patients with overlap syndrome may not lead to an improvement in the coexistent COPD.     

CPAP Does Not Reduce High-Sensitivity C-Reactive Protein in Patients With Coronary Artery Disease and Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) is associated with an increase in high-sensitivity C-reactive protein (hs-CRP). Studies suggested that the degree of severity of OSA in obese patients with no known coronary artery disease correlates with higher levels of hs-CRP and that continuous positive airway pressure (CPAP) could reduce this inflammation marker. In this study we tested the hypothesis that CPAP therapy could also reduce hs-CRP in cardiac patients with multiple comorbidities and known OSA. Sixty-two consecutive patients were included in this study. All patients were referred for a sleep test because of clinical suspicion of OSA. Clinical variables, body mass index (BMI), hs-CRP, and lipid profile were obtained at the time of their referral and at 126.2 ± 33.7 days followup. Thirty-four patients (group A) underwent CPAP therapy and 28 patients did not (group B). The linear regression of hs-CRP level on the severity of the apnea–hypopnea index (AHI) was significant (p = 0.05), but this significance is lost when ln(hs-CRP) was used (p = 0.263). Through analysis of covariance, ln(hs-CRP) was predicted by BMI (p = 0.000) (R-Sq = 46.2%). In group A, and despite a significant drop in the AHI with CPAP [median difference = −29.7 (−41.8, −22.2)], there were no significant differences in patients’ BMI, lipid profile, or hs-CRP [median difference = −0.15 (−0.83, 0.64)] (p = 0.53) on followup. When both groups A and B were compared, they had matched BMI, lipids, ejection fraction, blood pressure, age, creatinine, awake O₂ saturations, alcohol consumption, coronary artery disease, and baseline and followup hs-CRP despite significant differences in baseline AHI (37.65 vs 14.30, respectively, p = 0.000). We conclude that the degree of OSA or CPAP treatment does not independently predict levels of ln(hs-CRP) in cardiac outpatients when other clinical variables, BMI, and lipids are adjusted for. BMI remains the strongest independent predictor of hs-CRP in this patient population. Supported by the Midwest Cardiovascular Research Foundation, Davenport, Iowa.     

Association between sleep apnea severity and blood coagulability: treatment effects of nasal continuous positive airway pressure

A prothrombotic state may contribute to the elevated cardiovascular risk in patients with obstructive sleep apnea (OSA). We investigated the relationship between apnea severity and hemostasis factors and effect of continuous positive airway pressure (CPAP) treatment on hemostatic activity. We performed full overnight polysomnography in 44 OSA patients (mean age 47±10 years), yielding apnea–hypopnea index (AHI) and mean nighttime oxyhemoglobin saturation (SpO₂) as indices of apnea severity. For treatment, subjects were double-blind randomized to 2 weeks of either therapeutic CPAP (n=18), 3 l/min supplemental nocturnal oxygen (n=16) or placebo–CPAP (<1 cm H₂O) (n=10). Levels of von Willebrand factor antigen (VWF:Ag), soluble tissue factor (sTF), D-dimer, and plasminogen activator inhibitor (PAI)-1 antigen were measured in plasma pre- and posttreatment. Before treatment, PAI-1 was significantly correlated with AHI (r=0.47, p=0.001) and mean nighttime SpO₂ (r=−0.32, p=0.035), but these OSA measures were not significantly related with VWF:Ag, sTF, and D-dimer. AHI was a significant predictor of PAI-1 (R ²=0.219, standardized β=0.47, p=0.001), independent of mean nighttime SpO2, body mass index (BMI), and age. A weak time-by-treatment interaction for PAI-1 was observed (p=0.041), even after adjusting for age, BMI, pre-treatment AHI, and mean SpO₂ (p=0.046). Post hoc analyses suggested that only CPAP treatment was associated with a decrease in PAI-1 (p=0.039); there were no changes in VWF:Ag, sTF, and D-dimer associated with treatment with placebo–CPAP or with nocturnal oxygen. Apnea severity may be associated with impairment in the fibrinolytic capacity. To the extent that our sample size was limited, the observation that CPAP treatment led to a decrease in PAI-1 in OSA must be regarded as tentative.     

Craniofacial anatomical risk factors in men with obstructive sleep apnea and heart failure: a pilot study

Purpose

Obstructive sleep apnea (OSA) is complicated with heart failure (HF); however, the reason for this is not well understood. Craniofacial anatomic risk factors may contribute to OSA pathogenesis in HF patients. However, there are no data about cephalometric findings among OSA patients with HF.

Methods

Consecutive patients with HF and OSA (defined as total apnea–hypopnea index (AHI) ≥15/h) were enrolled. As controls, OSA patients without HF but matching the test group in age, BMI, and obstructive AHI were also enrolled.

Results

Overall, 17 OSA patients with HF and 34 OSA patients without HF were compared. There are no significant differences in the characteristics or polysomnographic parameters between 2 groups. In the cephalometric findings, compared with patients without HF, patients with HF showed a significantly greater angle between the line SN to point “A” (SNA) and a longer inferior airway space and greater airway area. However, the tongue area of patients with HF was more than those without HF.

Conclusions

The craniofacial structures of OSA patients with HF were different from those without HF. OSA patients with HF had an upper airway anatomy that is more likely to collapse when sleeping while recumbent, despite having a larger airway space.     

Optimal continuous positive airway pressure in patients with obstructive sleep apnoea: role of craniofacial structure

Although nasal continuous positive airway pressure (CPAP) is effective in improving nocturnal obstructive apnoea, daytime sleepiness and well-being in patients with obstructive sleep apnoea syndrome (OSAS), not all patients tolerate this treatment. Since optimal CPAP titration is essential to maintain compliance, it is important to elucidate the factors that help to determine the optimal pressure. However, the determinants of the optimal CPAP level are controversial. The subjects comprised 27 Japanese male patients with OSAS who underwent standard polysomnography (PSG), pulmonary function tests, arterial blood gas analysis, cephalometry and CPAP titration. Twenty normal controls also underwent cephalometric analysis. The apnoea-hypopnoea index (AHI), mean oxygen saturation (mean SaO2) and the lowest SaO2 during sleep were found to be 54.7+/-22.6, 89.0+/-5.6%, and 69.7+/-9.0%, respectively by PSG. The mean optimal CPAP was 9.6+/-1.8 cmH2O. The cephalometric angles (SNA, SNB and NSBa) were similar to those found in the control subjects. but MP-H, and PNS-P were significantly longer than those in the control subjects as shown by cephalometry. The optimal CPAP was correlated with the mean SaO2 (P<0.0001), neck circumference (P<0.05) and three cephalometric variables (NSBa: P<0.01, MP-H: P<0.05, PNS-P: P<0.05). Multiple, step-wise, regression analysis showed that the mean SaO2 and NSBa were independent variables that best predicted the optimal CPAP. These variables accounted for 57.5% of the total variance (R2=0.575, P<0.001). Optimal CPAP was closely correlated with oxygen desaturation during sleep. However, the craniofacial structure had additional effects such as an independent factor in determining the optimal CPAP level.     

Cephalometric abnormalities in non-obese and obese patients with obstructive sleep apnoea.

The aim of this work was to comprehensively evaluate the cephalometric features in Japanese patients with obstructive sleep apnoea (OSA) and to elucidate the relationship between cephalometric variables and severity of apnoea. Forty-eight cephalometric variables were measured in 37 healthy males and 114 male OSA patients, who were classed into 54 non-obese (body mass index (BMI) <27 kg x m(-2), apnoea-hypopnoea index (AHI)=25.3+/-16.1 events x h(-1)) and 60 obese (BMI > or = 27 kg x m(-2), AHI=45.6+/-28.0 events h(-1)) groups. Diagnostic polysomnography was carried out in all of the OSA patients and in 19 of the normal controls. The non-obese OSA patients showed several cephalometric defects compared with their BMI-matched normal controls: 1) decreased facial A-P distance at cranial base, maxilla and mandible levels and decreased bony pharynx width; 2) enlarged tongue and inferior shift of the tongue volume; 3) enlarged soft palate; 4) inferiorly positioned hyoid bone; and 5) decreased upper airway width at four different levels. More extensive and severe soft tissue abnormalities with a few defects in craniofacial bony structures were found in the obese OSA group. For the non-obese OSA group, the stepwise regression model on AHI was significant with two bony structure variables as determinants: anterior cranial base length (S-N) and mandibular length (Me-Go). Although the regression model retained only linear distance between anterior vertebra and hyoid bone (H-VL) as an explainable determinant for AHI in the obese OSA group, H-VL was significantly correlated with soft tissue measurements such as overall tongue area (Ton), inferior tongue area (Ton2) and pharyngeal airway length (PNS-V). In conclusion, Japanese obstructive sleep apnoea patients have a series of cephalometric abnormalities similar to those described in Caucasian patients, and that the aetiology of obstructive sleep apnoea in obese patients may be different from that in non-obese patients. In obese patients, upper airway soft tissue enlargement may play a more important role in the development of obstructive sleep apnoea, whereas in non-obese patients, bony structure discrepancies may be the dominant contributing factors for obstructive sleep apnoea.     

Pressure-Heart Rate Responses to α-Adrenergic Stimulation and Hormonal Regulation in Normotensive Patients With Obstructive Sleep Apnea

Seven normotensive untreated patients with obstructive sleep apnea (OSA) and five control subjects without OSA were compared. Patients with cardiac dilation, chronic airflow limitation, liver and kidney disease, or diabetes mellitus were excluded. Change in pressure-heart rate relation to α-adrenergic stimulation (P-HRR), extracellular volume (ECV), and plasma volume (V_p) were measured during daytime. Plasma atrial natriuretic peptide (ANP), plasma renin and aldosterone concentrations were obtained at 1 hour intervals during the night. A mean apnea/hypopnea index (AHI) of 52.2 ± 23.9/h and a mean lowest arterial oxygen saturation (SaO₂) of 61.2 ± 19.3% (mean ± SD) were determined from polysomnographic monitoring in the patient group. Release of ANP was significantly higher during sleep in OSA patients than in control subjects (P < .01), with a maximum concentration between 4 and 6 am in the former. Daytime ECV was significantly higher (P < .05) and V_p significantly lower (P < .05) in OSA patients. Night maximum concentration of ANP (max ANP) was negatively related to AHI (P < .05). P-HRR was negatively related to AHI (P < .05) and positively related to max ANP (P < .05). In conclusion, OSA syndrome alters hormonal system control of body fluid compartment regulation. The decreased response in night max ANP secretion in the most severe OSA patients could be explained by the smaller V_p observed in these patients, decreasing atrial and ventricular pressure loading. Furthermore, alteration of P-HRR, correlated to AHI and max ANP, strengthens the hypothesis that patients who develop hypertension are those in whom the protective mechanism of ANP release failed.     

Auto bi-level pressure relief–PAP is as effective as CPAP in OSA patients—a pilot study

Purpose

Continuous positive airway pressure (CPAP) is the therapy of choice for the treatment of obstructive sleep apnea (OSA). Not all patients can use CPAP therapy with adequate compliance. There is a need to develop more comfortable modes. Auto bi-level Pressure Relief-Positive Airway Pressure (ABPR-PAP) can be an alternative. We conducted a prospective double-blind, randomised trial to evaluate the efficacy and compliance of ABPR-PAP compared with CPAP in OSA patients.

Methods

We included 35 CPAP naive patients (age 53.3?±?10.3?years, BMI 31.0?±?5.0?kg/m², ESS 10.0?±?4.2) diagnosed with moderate to severe OSA who underwent a successful CPAP titration. Patients were randomised into the CPAP or the ABPR-PAP treatment group. We used the same device (BIPAP? Auto, Philips Respironics) for CPAP or ABPR-PAP. Apnea?Chypopnea index (AHI) was determined using polysomnography before (AHI 40.6?±?18.3 per hour) and after treatment.

Results

Eighteen patients received CPAP and the remaining 17 received APBR-PAP. Groups were similar in terms of demographics and OSA severity. There were no serious adverse events during the trial. CPAP was fixed by a sleep expert and ABPR-PAP varied (range 5?C15?cmH₂O). AHI decreased in the CPAP group to 6.4?±?5.7 per hour and in the ABPR-PAP group to 4.8?±?3.6 per hour in the first night (N?=?35). After 3?months, the AHI decreased in the CPAP group to 4.4?±?5.3 per hour and in the ABPR-PAP group to 2.6?±?3.8 per hour (N?=?32). Differences between the groups were not statistically significant. There were no differences in compliance.

Conclusions

ABPR-PAP is a promising new ventilation mode that enables effective treatment of OSA patients.     

Obesity hypoventilation syndrome: hypoxemia during continuous positive airway pressure

BACKGROUND: Polysomnography findings between matched groups with obstructive sleep apnea (OSA) and OSA plus obesity-hypoventilation syndrome (OHS) before and after continuous positive airway pressure (CPAP), particularly in the extremely severe obese (body mass index [BMI] >or= 50 kg/m2), are unclear. DESIGN: Prospective study of subjects (BMI >or= 50 kg/m2) undergoing diagnostic polysomnography. Subjects with an apnea-hypopnea index (AHI) >or= 15/h underwent a second polysomnography with CPAP. The effect of 1 night of CPAP on sleep architecture, AHI, arousal indexes, and nocturnal oxygenation was assessed. OHS was defined as those subjects with obesity, PaCo2 > 45 mm Hg, and PaO2 < 70 mm Hg in the absence of lung disease. RESULTS: Twenty-three subjects with moderate-to-severe OSA and 23 subjects with moderate-to-severe OSA plus OHS underwent a 1-night trial of CPAP. Both groups were matched for spirometry, BMI, and AHI, but oxygen desaturation was worse in the OSA-plus-OHS group. CPAP significantly improved rapid eye movement (REM) duration (p < 0.005), AHI (p < 0.005), arousal indexes (p < 0.005), and percentage of total sleep time (TST) with oxygen saturation (SpO2) < 90% (p < 0.005) in both groups. In subjects with OSA plus OHS, 43% continued to spend > 20% of TST with SpO2 < 90%, compared to 9% of the OSA group, despite the adequate relief of upper airway obstruction. CONCLUSIONS: Extremely severe obese subjects (BMI >or= 50 kg/m2) with moderate-to-severe OSA plus OHS exhibit severe oxygen desaturation but similar severities of AHI, arousal indexes, and sleep architecture abnormalities when compared to matched subjects without OHS. CPAP significantly improves AHI, REM duration, arousal indexes, and nocturnal oxygen desaturation. Some subjects with OHS continued to have nocturnal desaturation despite the control of upper airway obstruction; other mechanisms may contribute. Further long-term studies assessing the comparative role of CPAP and bilevel ventilatory support in such subjects with OHS is warranted.     

The use of a predicted CPAP equation improves CPAP titration success

Titration of continuous positive airway pressure (CPAP) is performed to determine the CPAP setting to prescribe for an individual patient. A prediction equation has been published that could be used to improve the success rate of CPAP titrations. The goals of this study were: (1) to test the hypothesis that the use of the prediction equation would achieve a higher rate of successful CPAP titrations; (2) to validate the equation as an accurate predictor of the prescribed CPAP setting and determine the factors that influence the accuracy of the prediction equation. A total of 224 patients underwent CPAP titration prior to using the equation, with a starting pressure of 5 cm H₂O. A total of 192 patients underwent CPAP titration using the equation-predicted CPAP level as the starting pressure (median starting pressure of 8 cm H₂O [interquartile range 7, 10 cm H₂O]). The percentage of successful studies, as defined by a 50% decrease in the apnea–hypopnea index (AHI) and a final AHI 10 cm H₂O, increased from 50% to 68% (p<0.001), while the number of patients who were prescribed a CPAP level that had not been tested decreased from 22% to 5% (p<0.001). The equation was not accurate in predicting the prescribed level of CPAP, with only 30.8% of the patients with a prescribed pressure 3 cm H₂O of the predicted pressure. Female gender was the only predictor of a prescribed pressure 3 cm H₂O from the predicted pressure (odds ratio 3.45, 95% confidence intervals 1.67, 7.13, p<0.001). A CPAP prediction equation modestly increases the rate of successful CPAP titrations by increasing the starting pressure of the titration. The equation does not accurately predict the prescribed CPAP level, reaffirming the need for a titration study to determine the optimal prescribed level in a given patient.     

Cephalometric assessment of craniofacial morphology in Chinese patients with obstructive sleep apnoea

OBJECTIVE: To compare the differences in craniofacial morphology in Chinese patients with and without obstructive sleep apnoea (OSA). METHOD: We performed lateral cephalometric radiographs on 94 consecutive patients (77 males) referred with snoring or other symptoms suggestive of OSA for polysomnography (PSG). Significant OSA was defined as an apneoa-hypopnoea index (AHI) > or = 10/h of sleep on overnight PSG. The cephalometric data were compared between those with and without significant OSA. RESULTS: (mean +/- SD) There were 69 (56 males) with significant OSA with mean age 53 +/- 12 years, body mass index (BMI) 28.6 +/- 5.0 kg/m2, AHI 36.5 +/- 20.6/h, and minimum SaO2 76 +/- 14%. There were 25 controls (21 males) without significant OSA with similar age and BMI. The mandibular plane to hyoid bone distance (MPH) and the perpendicular distance from hyoid bone to the line connecting C3 vertebra and retrognathion (HHI) were significantly longer in the OSA patients. The angle measurement from sella to nasion to point A (SNA) was smaller in the OSA group. MPH distance was the only independent variable for significant OSA with an odds ratio of 3.47 (95% CI 1.39-8.66). Abnormalities of the MPH and SNA were more marked in the OSA patients with BMI > or = 30 kg/m2. CONCLUSIONS: Significant differences in craniofacial morphology are noted between OSA patients and non-apnoeic controls. An inferiorly positioned hyoid bone and a retropositioned maxilla may predispose obese patients to more severe OSA.     

Ethnicity and socioeconomic status predict initial continuous positive airway pressure compliance in New Zealand adults with obstructive sleep apnoea

Background: Understanding factors that contribute to low continuous positive airway pressure (CPAP) compliance will lead to improvements in the long‐term outcome of patients with obstructive sleep apnoea (OSA) syndrome. Both cultural and socioeconomic factors are likely to be important but have not been systematically studied. Aim: To examine the effect of ethnicity and socioeconomic status on initial CPAP usage for people with OSA in New Zealand. Methods: We retrospectively collected demographic, clinical and CPAP treatment‐related data on patients undergoing a 1‐month CPAP trial for a 10‐month period. We compared objectively measured CPAP usage (by anova ) with self‐identified ethnicity; levels of socioeconomic deprivation (NZDep06 index), Epworth Sleepiness Scale (ESS) and Apnoea‐Hypopnoea Index (AHI). Results: A total of 214 patients with a mean age of 52.7 (±11.8) years, mean AHI 57.3 (±35.8) events per hour and mean ESS 13 (±5.58)/24 made up the cohort. CPAP usage which averaged 5.13 ± 2.34 h per night was significantly lower in patients of non‐European ethnicity (P = 0.019 univariate) and remained significant after socioeconomic status was added to the model (P = 0.048). Patients living in the most socioeconomically deprived areas showed significantly lower compliance with CPAP on univariate analysis (P = 0.024, NZDep06 scores 1&2, average 5.3 per night compared to score NZDep06 scores 9&10, average 4.3 h per night), but this effect was no longer significant once ethnicity was added to the model (P = 0.28). Conclusion: CPAP usage in New Zealand is affected by both ethnicity and level of socioeconomic deprivation. We recommend further research to unravel specific cultural and socioeconomic reasons for the variance reported.     

Nasal versus oronasal continuous positive airway pressure masks for obstructive sleep apnea: a pilot investigation of pressure requirement, residual disease, and leak

Purpose

This single-blinded, randomized, controlled pilot study aimed to investigate whether there is a difference between nasal and oronasal masks in therapeutic continuous positive airway pressure (CPAP) requirement, residual disease, or leak when treating obstructive sleep apnea (OSA) and if differences were related to measures of upper airway size.

Methods

Patients with severe OSA currently using CPAP at ??4?h/night with a nasal mask were examined (including Mallampati scale, incisal relationship, and mandibular protrusion) and then randomized to receive auto-positive airway pressure (PAP) or fixed CPAP at a manually titrated pressure for 1?week each at home, with immediate crossover. Within each week, a nasal mask and two oronasal masks were to be used for two or three nights each in random order. Data were downloaded from the device.

Results

Twelve patients completed the trial (mean ± SD AHI 59.8?±?28.6 events/h; CPAP 11.1?±?3.2?cmH₂O; BMI 37.7?±?5.0?kg/m²). During auto-PAP, the median 95th percentile pressure delivered with all masks was within 0.5?cmH₂O (p?>?0.05). During CPAP, median residual AHI was 0.61 (IQR?=?1.18) for the nasal mask, 1.70 (IQR?=?4.04) for oronasal mask 1, and 2.48 (IQR?=?3.74) for oronasal mask 2 (p?=?0.03). The 95th percentile leak was lowest with the nasal mask during both CPAP and auto-PAP (both p?Conclusions In obese OSA patients changing from a nasal to oronasal mask increased leak and residual AHI but did not affect the therapeutic pressure requirement. The findings of the current study highlight mask leak as the major difficulty in the use of oronasal masks.     

Association between hydrogen sulfide and OSA-associated hypertension: a clinical study

Purpose

We sought to unravel the role of hydrogen sulfide (H₂S) in the development of hypertension in patients with obstructive sleep apnea (OSA).

Methods

The study sample included 80 patients with OSA and 45 healthy controls. All subjects underwent measurement of blood pressure (BP) and serum H₂S level in the morning. Twentynine of the 39 patients with OSA and concomitant hypertension and 23 of the 41 patients with OSA but no concomitant hypertension received continuous positive alveolar pressure (CPAP) therapy for 4 weeks. Twenty-four-hour ambulatory BP and serum H₂S were determined before and after CPAP. Respiratory indices including apnea hypopnea index (AHI), lowest oxygen saturation (SaO₂), and length of time < 90% saturated (T90) were determined by polysomnography.

Results

Associations between H₂S, BP, respiratory indices, and changes with CPAP were analyzed. OSA patients had significantly higher systolic BP (p = 0.003) and diastolic BP (p = 0.009) and lower H₂S levels (p = 0.02) compared to healthy controls. H₂S negatively correlated with AHI (p = 0.005), T90 (p = 0.009), morning systolic BP (p = 0.02), and morning diastolic BP (p = 0.03). All respiratory indices were significantly improved (p < 0.05) after CPAP in OSA patients with or without hypertension. BP was significantly reduced and H₂S significantly increased after CPAP in OSA patients with hypertension (p < 0.05) but not in OSA patients without hypertension (p > 0.05).

Conclusion

Multivariate linear regression analysis demonstrated that 24h systolic BP and 24h diastolic BP correlated with H₂S as well as their changes after CPAP treatment. Reduction in H₂S may play a role in the pathogenesis of hypertension in patients with OSA.

     

Pressure adjustment is the most useful intervention for improving compliance in telemonitored patients treated with CPAP in the first 6 months of treatment

Purpose

Telemonitoring (TMg) for patients treated with continuous positive airway pressure (CPAP) is now routine care in some sleep labs. The purpose of the present study was to identify technical interventions associated with improved CPAP compliance in a real-life cohort of newly telemonitored patients with obstructive sleep apnea (OSA) during the first 6 months of treatment.

Methods

All patients with moderate-to-severe OSA (apnea-hypopnea index (AHI) ≥ 15/h) who were newly treated with CPAP were included in the study and telemonitored. A group educational session was scheduled after 1 month. Technical interventions were performed at the patient’s request and during scheduled visits and the impact of each intervention on CPAP therapy compliance was collected.

Results

Between May 2018 and Dec 2019, 349 patients newly diagnosed with OSA were hospitalized in the sleep lab for CPAP titration and 212 patients were included (mean age 54.6 ± 13.1 years, mean BMI 31.7 ± 5.8 kg/m², mean AHI 42.8 ± 22.0). TMg acceptance rate was 87%. Mean 6-month compliance was 275 ± 154 min, 13% stopped CPAP, and 17% were non-compliant. Correlations were observed between BMI (r = 0.15, p = 0.029), median and 95th percentile leaks (r = ?0.23 and ?0.18, p = 0.016 and 0.002), and CPAP compliance.

During follow-up, 92 interventions were required, mainly for mask change (n = 80). Pressure modification (n = 16) was the only intervention that increased CPAP use > 30 min/night, p = 0.021.

Conclusion

Pressure modification was the only adaptation that significantly increased CPAP compliance during the first 6 months. Remote TMg allows providing daily, accurate, and immediate feedback that could help clinicians to confirm that the CPAP treatment is effective.

     

Effects of surgical weight loss for treating obstructive sleep apnea

Purpose

Weight loss has been reported to reduce the severity of obstructive sleep apnea (OSA), particularly in the obese population. However, prospective studies with polysomnography (PSG) for the precise evaluation of OSA are lacking especially in Asian countries. We evaluated the effects of surgical weight loss for treating OSA using PSG data obtained before and after surgery.

Methods

We performed a prospective study analyzing the clinical and PSG data obtained from our cohort of bariatric surgical candidates with moderate to severe OSA, as confirmed by preoperative PSG. The patients underwent follow-up PSG at least 12 months after bariatric surgery (laparoscopic Roux-en-Y gastric bypass).

Results

Of the 47 patients (70.1 %) with moderate to severe OSA among 67 patients who underwent preoperative PSG, 10 patients underwent postoperative PSG. The mean apnea-hypopnea index (AHI) of these 10 patients significantly reduced from 51.0?±?34.2 to 9.3?±?12.9 events/h, while their mean body mass index (BMI) loss was from 39.9?±?8.3 to 26.9?±?4.4 kg/m². Although the severity of OSA improved considerably, OSA resolution was achieved in only five patients (50 %). When compared to the patients who achieved OSA resolution, the patients with residual OSA showed a tendency to have lower minimum arterial oxygen saturation (SaO₂) levels and higher supine AHI values in preoperative PSG.

Conclusions

Surgical weight loss resulted in the significant improvement of OSA associated with obesity. However, OSA remained in a considerable proportion of patients even after substantial weight loss. We recommend that postoperative PSG be considered for the evaluation of residual OSA, especially in patients with low minimum SaO₂ levels and high supine AHI in preoperative PSG.     

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.

     

The effects of long‐term continuous positive airway pressure on apnea–hypopnea index change following short‐term that withdrawal in patients with obstructive sleep apnea

The effect of long‐term continuous positive airway pressure (CPAP) treatment on apnea–hypopnea index (AHI) after CPAP withdrawal remains unclear, especially in obstructive sleep apnea (OSA) patients screened from the population. To examine that, 1241 civil servants who participated in the annual physical examination were screened for OSA between September and December 2017. Screened OSA firstly underwent 1‐week CPAP adherence assessment. Then, patients with good CPAP adherence would be freely provided CPAP to continued treatment. All OSA patients were followed for 2 years. At study end, all OSA patients underwent home sleep testing (HST) again within 1 week of CPAP withdrawal. The effect of 2‐year CPAP treatment on OSA severity was investigated by using linear regression and multinominal logistic regression. In total, 103 OSA patients were screened, including 41 cases (39.8%) in CPAP treatment group and 62 cases (60.2%) in non‐CPAP treatment group. At 2‐year follow‐up, compared with baseline, in CPAP treatment group, following CPAP withdrawal, a significant decrease in AHI was observed in patients with severe OSA (P = 0.014); in non‐CPAP treatment group, a significant increase in AHI was observed in patients with moderate OSA (P = 0.028). After adjustment for confounding factors, multivariate linear regression showed that △AHI was negatively associated with CPAP treatment (β = −4.930, 95% confidence interval [CI] [−9.361, −0.500], P = 0.030). Multinominal logistic regression showed that the AHI of patients not treated with CPAP tended to be unchanged or worsened with the AHI improvement group as a reference (OR [odds ration] [95% CI], 4.555 [1.307, 15.875], P = 0.017; 6.536 [1.171, 36.478], P = 0.032). In conclusion, active OSA screening and long‐term CPAP intervention may improve the severity of severe OSA patients following short‐term CPAP withdrawal in the general population.