Continuous Positive Airway Pressure Titration Research Articles

Fixed and Autoadjusting Continuous Positive Airway Pressure Treatments Are Not Similar in Reducing Cardiovascular Risk Factors in Patients With Obstructive Sleep Apnea

A strong association between obstructive sleep apnea (OSA) and the risk for cardiovascular and cerebrovascular diseases has been reported. Continuous positive airway pressure (CPAP) is the first-line therapy for OSA, able not only to reduce daytime sleepiness but also to improve cardiovascular and metabolic outcomes. Autoadjusting CPAP (APAP), an alternative treatment to CPAP, can reduce OSA symptoms while increasing long-term CPAP compliance without the high costs of CPAP titration. However, no data are available on the effects of APAP on cardiovascular risk factors We performed standard full polysomnography; obtained plasma levels of glucose, insulin, and C-reactive protein (CRP); and measured systolic BP (SBP) and diastolic BP (DBP) in 31 patients with newly diagnosed, severe OSA. After standard CPAP titration, all subjects were randomized to CPAP or APAP treatment. Measurements were obtained at baseline and after 3 months of treatment. The two groups were similar in terms of age, sex, body mass index (BMI), and severity of OSA. SBP, DBP, heart rate (HR), homeostasis model assessment index (HOMA-IR), and CRP were similar in the two groups. After 3 months of treatment, BMI, HR, and compliance to therapy were also comparable. OSA indexes were significantly reduced in both groups. Significant reductions in SBP, DBP, and HOMA-IR were observed in the CPAP group but not in the APAP group, while CRP plasma levels were similarly reduced. Our results suggest that CPAP and APAP, despite significant effects on OSA indexes and symptoms, do not improve cardiovascular risk factors in the same fashion.

CPAP titration: Different methods for similar clinical results

Background Continuous positive airway pressure (CPAP) is the main treatment for obstructive sleep apnea–hypopnea syndrome (OSAHS). Polysomnography (PSG) is the gold standard for CPAP titration. However, alternative methods have been sought to titrate CPAP at less expense in terms of time and resources. The aim of this study was to analyze CPAP success in controlling OSAHS symptoms and adverse effects by two titration methods. Methods This was a retrospective, observational cohort study in which 200 CPAP-naive patients who had been referred to our sleep laboratory and diagnosed with OSAHS were evaluated on two consecutive visits. During the first visit, an initial CPAP pressure was established either by split-night PSG or by using a mathematical formula. On the second visit, 1 month later, symptom persistence and adverse effects of CPAP treatment were assessed. Results Patients included were 157 males (78.5%) and 43 females (21.5%) aged 56 ± 10 years. 87 patients (43.5%) were titrated by PSG and 113 (56.5%) using the formula. At the second visit, symptoms had improved significantly for both groups with no significant differences in the presence of adverse effects. The initial pressure had to be readjusted in five patients. Conclusions This study suggests that formula titration can control symptoms as effectively as split-night titration. A prompt evaluation of the patient is advisable in order to ensure compliance with treatment and to correct possible adverse effects.

Persistent sleepiness in CPAP treated obstructive sleep apnea patients: Evaluation and treatment

Nasal continuous positive airway pressure (CPAP) is an effective treatment for most patients with obstructive sleep apnea syndrome (OSAS), improving sleepiness, cognitive function and mood. A number of patients, however, complain about persistent sleepiness after CPAP. In these cases another clinical history should be carried out to confirm the diagnosis of OSAS, to check CPAP compliance and to exclude associated conditions such as poor sleep hygiene, depression, narcolepsy or idiopathic hypersomnia. If necessary, a full polysomnography (PSG) followed by a multiple sleep latency test or even a full PSG with CPAP titration should be performed. Experimental data in animals suggest that long-term intermittent hypoxia related to the apneic events could deteriorate the brain structures that regulate alertness. This impairment, if present in humans, could be another reason for residual sleepiness after CPAP. Modafinil has been shown to reduce subjective sleepiness after CPAP in OSAS patients. Further studies are warranted to clarify the way in which CPAP modifies sleepiness.

The fine art of CPAP titration—will it ever become obsolete?

Continuous positive airway pressure (CPAP) became the most effective treatment for obstructive sleep apnea (OSA). The assessment of the effective pressure for treatment has not yet changed in the 25 years of clinical practice. The adjustment of the correct pressure level is accomplished during a step-by-step titration on a “trial and error” basis. That means the pressure applied to the mask will be gradually increased until all respiratory events (i.e., apneas, hypopneas, and snoring) are abolished. The procedure happens during the night sleep in the sleep laboratory under visual control of the sleep and cardiorespiratory parameters. The financial pressure and the need to reduce the expenses of medical services triggered efforts to minimize the costs and replace the time-, manpower-, and moneyconsuming “gold standard” practice in the sleep laboratory. In the 25-year-old history of CPAP therapy, we now

The Effect of One Versus Two Nights of In-Laboratory Continuous Positive Airway Pressure Titration on Continuous Positive Airway Pressure Compliance

Objective: To investigate continuous positive airway pressure (CPAP) compliance after one versus two nights of CPAP titration. Method: A chart review and a telephone questionnaire interview were conducted in 110 sleep apnea patients who received one or two nights of CPAP titration. Of these patients, 78 followed through with phone interview. Results: There was no difference in CPAP compliance between those who had one or two nights of CPAP titration. The titration pressures on the first and second nights were not significantly different. But there was significant improvement in sleep efficiency from the first to the second diagnostic night. Conclusion: One versus two nights of CPAP titration did not affect CPAP compliance, but sleep efficiency improved on the second diagnostic night and an extra titration study may be necessary for some patients, especially those with only one diagnostic night.

Automatic Pressure Titration with APAP Is as Effective as Manual Titration with CPAP in Patients with Obstructive Sleep Apnea

Background: The optimal approach to initiate positive-pressure therapy in patients with obstructive sleep apnea is still debated. Current options are autotitrating positive airway pressure (APAP) or manual titration with continuous positive airway pressure (CPAP). Procedures differ by parameters and by algorithms used for adapting pressure. Objectives: To evaluate the efficacy of attended automatic titration in a randomized crossover study compared with manual titration over 2 nights where the sequence of the titration mode was changed. Therapy outcome was controlled after 6 weeks. Methods: 21 sleep apnea patients were treated using manual CPAP versus automatic APAP titration. The mode used during the 2nd night was continued for 6 weeks. Cardiorespiratory polysomnography, Epworth Sleepiness Scale (ESS), SF-36 score and compliance were assessed. Results: Apnea-hypopnea index reduction was equally effective at similar effective pressure independent of the titration mode. If APAP was applied during the 1st night, total sleep time was longer (384 vs. 331 min, p < 0.01) and sleep efficacy was higher (91 vs. 81%, p < 0.01) than after starting with manual titration with CPAP. Compliance was comparable in both groups (4.6 ± 1.9 h). The ESS improved in both groups (from 12.9 to 6.5). SF-36 scores and therapeutic pressure did not much change. Conclusions: Taking the sequence of titration into account, we found equal effectiveness of CPAP and APAP. Sleep quality was better with initial application of APAP – which favors attended automatic titration if only 1 titration night is possible. Both modes are comparable after 6 weeks regarding therapeutic pressure, efficacy, compliance and quality of life.

Diagnosis and Initial Management of Obstructive Sleep Apnea without Polysomnography

Polysomnography (PSG), despite limited availability and high cost, is currently recommended for diagnosis of obstructive sleep apnea and titration of effective continuous positive airway pressure (CPAP). To test the utility of a diagnostic algorithm in conjunction with ambulatory CPAP titration in initial management of obstructive sleep apnea. A randomized, controlled, open-label trial that compared standard PSG with ambulatory CPAP titration in high-risk patients identified by a diagnostic algorithm. A tertiary referral sleep disorders program in Vancouver, British Columbia, Canada. 68 patients with a high pretest probability of moderate to severe obstructive sleep apnea (apnea-hypopnea index [AHI] >15 episodes/h) identified by sequential application of the Epworth Sleepiness Scale (ESS) score, Sleep Apnea Clinical Score, and overnight oximetry. Patients were randomly assigned to PSG or ambulatory titration by using a combination of auto-CPAP and overnight oximetry. They were observed for 3 months. Apnea-hypopnea index on CPAP, ESS score, quality of life, and CPAP adherence. The PSG and ambulatory groups had similar median BMI (38 kg/m2), age (55 years), ESS score (14 points), and respiratory disturbance index (31 episodes of respiratory disturbance/h). Each episode is determined by a computer algorithm based on analysis of oxygen saturation measured by pulse oximetry. After 3 months, there were no differences in the primary outcome, AHI on CPAP (median, 3.2 vs. 2.5; difference, 0.8/h [95% CI, -0.9 to 2.3]) (P = 0.31), between the PSG and ambulatory groups, or in the secondary outcomes, ESS score, Sleep Apnea Quality of Life Index, and CPAP. Adherence to CPAP therapy was better in the ambulatory group than in the PSG group (median, 5.4 vs. 6.0; difference, -1.12 h/night [CI, -2.0 to 0.2]) (P = 0.021). In the initial management of patients with a high probability of obstructive sleep apnea, PSG confers no advantage over the ambulatory approach in terms of diagnosis and CPAP titration. The ambulatory approach may improve adherence to treatment. When access to PSG is inadequate, the ambulatory approach can be used to expedite management of patients most in need of treatment.

Daytime polysomnography for early diagnosis and treatment of patients with suspected sleep-disordered breathing

Excessive daytime sleepiness (EDS) is a common complaint among patients with sleep-disordered breathing (SDB). Population-based studies on traffic and industrial accidents suggest a relationship between EDS and life-threatening events, and adults with EDS have cognitive and memory problems. Nocturnal polysomnography (nPSG) is essential for diagnosing SDB but it is time and energy consuming. We examined the usefulness of daytime polysomnography (dPSG) for the early diagnosis and treatment of patients with suspected SDB. We studied 108 consecutive patients aged 51.9 +/- 13.5 years (mean+/-SD). All patients underwent dPSG and nPSG. The number of apnea/hypopnea episodes per hour (apnea/hypopnea index: AHI) and the number of 3% desaturation episodes per hour (desaturation index: DSI) were calculated. All patients were classified into two groups. The REM group consisted of subjects who had an AHI < or = 25/h, AHI(REM)/AHI(NREM) > 2, and AHI(NREM) < 15/h. Those who did not satisfy these criteria were placed in the NREM group. Continuous positive airway pressure (CPAP) titration was performed for patients whose AHI was > or =20/h on dPSG. Using the international classification of sleep disorders, 96 patients were diagnosed as obstructive sleep apnea [including five upper airway resistance syndrome (UARS) patients], six patients were snoring, four had idiopathic hypersomnia due to a medical condition, and two had circadian rhythm sleep disorders. The sensitivity of dPSG for AHI was 81.0%, specificity was 100%, and accuracy was 83.5%. The sensitivity and accuracy of dPSG for AHI in the REM group were considerably lower than in the NREM group. There was no significant difference for optimal CPAP between dPSG and nPSG. In the five patients with UARS, their AHI, DSI, and arousal index on dPSG were 0.92 +/- 1.2/h, 2.9 +/- 3.4/h, and 29.3 +/- 3.5/h, respectively, and their AHI and DSI on nPSG were 3.2 +/- 2.5/h and 2.8 +/- 2.4/h, respectively. However, their respiratory effort-related arousals were 37.9 +/- 7.4/h, and their arousal index was 33.2 +/- 6.3/h. The five patients with UARS were also treated with CPAP, and their daytime sleepiness was improved. Although dPSG has limitations, these results indicate that dPSG recording is clinically useful for the diagnosis of and determination of types of treatment in patients with suspected SDB.

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

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

Influence of Upper Airway Narrowing on the Effective Continuous Positive Airway Pressure Level

The aim of this study was to determine the relationship between the continuous positive airway pressure (CPAP) titration level and upper airway variables in obstructive sleep apnea syndrome (OSAS). Forty-seven patients suffering from OSAS were enrolled in this study. They were asked to answer a questionnaire about nasal stuffiness and mouth breathing, and the degree of tonsillar hypertrophy and shape of the oropharyngeal inlet were evaluated. The minimal cross-sectional area (MCA) of the nasal cavity was measured with acoustic rhinometry, followed by optimal CPAP level titration. We compared optimal CPAP levels with body mass index (BMI), perceived nasal stuffiness, and anatomic upper airway narrowing. The mean CPAP level was 6.32 +/- 2.17 cm H2O. We found a significant correlation between CPAP levels and BMI (P = .01), apnea-hypopnea index (P = .015), and the degree of tonsillar hypertrophy (P = .011). Furthermore, the CPAP level increased significantly with the MCA on the narrow side of the nasal cavity (P = .038) in patients with a BMI less than 25. Other variables, such as subjective symptoms and anatomic nasal airway occlusion in obese patients (BMI > or = 25), revealed no correlation with the CPAP level. Upper airway occlusion including nasal obstruction or tonsillar hypertrophy might increase the effective CPAP level.

Changes in dreaming induced by CPAP in severe obstructive sleep apnea syndrome patients

To study dream content in patients with severe obstructive sleep apnea syndrome (OSAS) and its modification with Continuous Positive Airway Pressure (CPAP) therapy. We assessed twenty consecutive patients with severe OSAS and 17 healthy controls. Polysomnograms were recorded at baseline in patients and controls and during the CPAP titration night, 3 months after effective treatment and 2 years later in patients. Subjects were awakened 5-10 min after the beginning of the first and last rapid eye movement (REM) sleep periods and we measured percentage of dream recall, emotional content of the dream, word count, thematic units, sleep architecture and REM density. Dream recall in REM sleep was similar in patients at baseline and controls (51.5% versus 44.4% respectively; P = .421), decreased to 20% and 24.3% the first and third month CPAP nights, and increased to 39% 2 years later (P = 0.004). Violent/highly anxious dreams were only seen in patients at baseline. Word count was higher in patients than in controls. REM density was highest the first CPAP night. Severe OSAS patients recall dreams in REM sleep as often as controls, but their dreams have an increased emotional tone and are longer. Despite an increase in REM density, dream recall decreased the first months of CPAP and recovered 2 years later. Violent/highly anxious dreams disappeared with treatment. A dream recall decrease with CPAP is associated with normalization of sleep in OSAS patients.

Prediction of continuous positive airway pressure in obstructive sleep apnea

Continuous positive airway pressure (CPAP) prediction formulas can potentially simplify the treatment of obstructive sleep apnea (OSA). However, they can be difficult to derive and validate. We tested a statistical method to derive and validate a CPAP prediction formula using the same sample population. Seventy-six OSA patients underwent polysomnography and CPAP titration. Anthropometric measures, sleep parameters, and the Epworth sleepiness scale (ESS) were evaluated as predictors. All subsets regression was used to determine the optimum number of variables in the model. The Bayes information criterion was used to find the best-fit model. The model was then evaluated by a tenfold cross-validation procedure. Subjects were obese (BMI 31.3 +/- 5.4) and had significant daytime somnolence (ESS 11.9 +/- 5). Mean respiratory disturbance index (RDI) was 53.5 +/- 31.3. The ESS was not predictive of titrated CPAP. The best-fit model included three variables (CPAP(pred) = 30.8 + RDI x 0.03 - nadir saturation x 0.05 - mean saturation x 0.2). This model explained 67% of the variance. Our data and the literature suggest that a combination of two to three factors is predictive of titrated CPAP: RDI, oxyhemoglobin saturation, and obesity. Except for RDI, the specific factors vary in each population. A CPAP prediction formula that explains a high proportion of the titrated CPAP variance can be easily derived from parameters measured during the diagnostic work-up of OSA patients using a unique statistical model that allows derivation and validation of the formula in the same test population.

Comparison of CPAP Titration at Home or the Sleep Laboratory in the Sleep Apnea Hypopnea Syndrome

Continuous positive airway pressure (CPAP) for the treatment of obstructive sleep apnea hypopnea syndrome (OSAHS) is conventionally started after in-laboratory overnight titration. This use of sleep laboratory space is both costly and limits access for diagnostic studies. This study aimed to evaluate whether automated CPAP titration in the home produced patient outcomes equal to those following laboratory-based automated CPAP titration. The main outcomes were Epworth Sleepiness Scale score, objective daytime sleepiness (Oxford SLEep Resistance test or OSLER test), and CPAP use; we also performed quality-of-life questionnaires: Functional Outcomes of Sleep Questionnaire and SF-36. Prospective, randomized, single-blind, parallel-group, controlled trial Regional sleep center and patients' homes. Two hundred CPAP-naïve patients with OSAHS requiring CPAP treatment. One hundred patients were randomly assigned to a standard 1-night in-hospital CPAP titration and 100 to 3 nights' home CPAP titration and then issued with fixed pressure CPAP. Data were analyzed on an intention-to-treat basis. The patient groups did not differ at baseline. The CPAP pressures defined at titration (mean+/- SEM: 10.6+/-0.2, 10.4+/-0.2 cm H20, p = .19), number of mask leaks, and initial acceptance rates were similar in the sleep-laboratory and home-titrated groups. At 3-month follow-up, there was no significant difference in CPAP use (mean+/-SEM: 4.39+/-0.25, 4.38+/-0.25 h/night; p > .9), Epworth Sleepiness Scale score (9.5+/-0.5, 8.5+/-0.5, p = .14), OSLER, Functional Outcomes of Sleep Questionnaire, or SF-36 between the sleep-laboratory and home-titrated groups. Home-based automated CPAP titration is as effective as automatic in-laboratory titrations in initiating treatment for OSAHS.

Pressure-Relief Continuous Positive Airway Pressure vs Constant Continuous Positive Airway Pressure: A Comparison of Efficacy and Compliance

To compare polysomnographic data and compliance in sleep apnea patients receiving continuous positive airway pressure (CPAP) and pressure-relief CPAP (PRCPAP) [C-flex; Respironics; Murrysville, PA] as first treatment in the sleep laboratory and subsequently at home. A prospective, randomized, crossover design was used in the sleep laboratory, and a prospective randomized design was used at home. Data were collected from 52 sleep apnea patients for whom CPAP was used for the first time. Treatment with constant CPAP and PRCPAP. Patients with a first-time diagnosis of obstructive sleep apnea syndrome (OSAS) underwent conventional CPAP titration. Thereafter, polysomnography was performed at the titrated pressure using both the fixed CPAP pressure mode and the PRCPAP mode in a randomized crossover approach. The patients were then discharged home for 7 weeks of treatment with the last-applied treatment mode, and compliance data were established at the end of that time. The average apnea-hypopnea index was 53.3/h in the "diagnostic night," 5.8/h with CPAP, and 7.0/h with PRCPAP. The native arousal index was 35.2/h, 12.6/h with CPAP, and 12.9/h with PRCPAP (not significant [NS]). The central apnea index was 0.7/h with CPAP and 1.2/h with PRCPAP (p < 0.05). Compliance after 7 weeks was, on average, 9.4 min longer with PRCPAP than with CPAP (NS). Evaluation of a 13-item questionnaire showed scores of 16.4 for PRCPAP and 18.1 for constant CPAP (NS) [the fewer the complaints, the lower the score]. With regard to oral dryness, the score with PRCPAP (1.4) was significantly lower than with constant CPAP (1.9) [p < 0.05]. This difference was no longer detectable after 7 weeks. In terms of the effectiveness in treating obstructive sleep apnea, PRCPAP and constant CPAP are comparable. During the first night of treatment, patients receiving PRCPAP had less dryness of mouth; over a period of 7 weeks, this difference disappeared. Nightly use of the device was comparable in both groups. PRCPAP is therefore a new ventilation mode that enables effective treatment of OSAS patients. Further studies should be done to investigate the effects of expiratory pressure lowering in low-compliance patients and patients requiring CPAP > 9 cm H(2)O or experiencing dry mouth with CPAP.

The Effect of 1 Week of Continuous Positive Airway Pressure Treatment in Obstructive Sleep Apnea Patients With Concomitant Gastroesophageal Reflux

Patients with obstructive sleep apnea (OSA) have a very high incidence of gastroesophageal reflux (GER). Previous studies have shown that the use of continuous positive airway pressure (CPAP) reduces the frequency of reflux events, but these studies only assessed the effect of a single night of treatment. The aim of this study was to assess the effect of 1 week of CPAP treatment on reflux in patients with OSA and GER. Sixteen patients with OSA and GER were recruited. Polysomnography followed by 24-h, continuous esophageal pH monitoring were performed at baseline. Patients with an apnea-hypopnea index (AHI) > 20/h and 24-h acid contact time (ACT) of at least 6% were included. As part of the polysomnography-qualifying evaluation, all patients underwent CPAP titration to reduce the AHI to < 10/h. Patients were then sent home receiving nasal CPAP for 1 week; after 1 week, esophageal pH monitoring was repeated while receiving CPAP. The AHI fell from 63.3 +/- 38.5 to 3.2 +/- 2.2/h (mean +/- SD) [p < 0.001]. Total ACT fell from 13.9 +/- 11.6 to 5.6 +/- 2.7% (p < 0.001). The upright ACT was reduced from 12.4 +/- 6.8 to 6.8 +/- 3.8% (p = 0.01), and the supine (during the sleeping interval) ACT was reduced from 16.3 +/- 18.8 to 3.8 +/- 7.6% (p < 0.01). Eighty-one percent of the patients had a reduction in supine ACT to within the normal range (< 4%). In OSA patients with significant heartburn complaints, CPAP would appear to be an efficacious approach to the treatment of both disorders.

A Comparison of the Long‐Term Outcome and Effects of Surgery or Continuous Positive Airway Pressure on Patients with Obstructive Sleep Apnea Syndrome

To compare the long-term (3-year) outcome and effects of continuous positive airway pressure (CPAP) and extended uvulopalatoplasty (EUPF) treatment on patients with obstructive sleep apnea syndrome. Eighty-four patients who received CPAP titration and bought a CPAP machine to use from March 2000 to October 2001 were included as the CPAP group. Another 55 patients who underwent EUPF surgery were included as the EUPF group. Overnight polysomnography was performed 6 months and 3 years after CPAP titration or EUPF. The disease-specific questionnaire-Snore Outcome Survey (SOS), Epworth Sleepiness Scale (ESS), and the generic health questionnaire-MOSF-36 were administered at the 6-month and 3-year follow-up examinations. The age, body mass index, respiratory disturbance index, and ESS before treatment were higher in the CPAP group. The snore index was higher in the surgery group. Fifty-four patients (64.3%) in CPAP group continued treatment for 6 months; the success rate for EUPF at 6 months was 82%. The polysomnographic variables improved significantly in both groups. Improvements in the SOS and ESS scores were better in surgery group than the CPAP group. The subscales of SF-36 in surgery group were more than those in CPAP group. EUPF had a better effect on snoring than CPAP 6 months after treatment in patients with obstructive sleep apnea syndrome (OSAS). This effect had gradually declined at the 3-year follow-up examination. Improvement in the quality of life of OSAS patients receiving EUPF is equal to those receiving CPAP treatment.

Does the Severity of Obstructive Sleep Apnea Predict Patients Requiring High Continuous Positive Airway Pressure?

To investigate polysomnographic and anthropomorphic factors predicting need of high optimal continuous positive airway pressure (CPAP). Retrospective data analysis. Three hundred fifty-three consecutive obstructive sleep apnea (OSA) patients who had a successful manual CPAP titration in our sleep disorders unit. The mean optimal CPAP was 9.5 +/- 2.4 cm H2O. The optimal CPAP pressure increases with an increase in OSA severity from 7.79 +/- 2.2 in the mild, to 8.7 +/- 1.8 in the moderate, and to 10.1 +/- 2.3 cm H2O in the severe OSA group. A high CPAP was defined as the mean + 1 standard deviation (SD; > or =12 cm H2O). The predictor variables included apnea-hypopnea index (AHI), age, sex, body mass index (BMI), Epworth Sleepiness Scale (ESS), and the Multiple Sleep Latency Test (MSLT). High CPAP was required in 2 (6.9%), 6 (5.8%), and 63 (28.6%) patients with mild, moderate, and severe OSA, respectively. On univariate analysis, AHI, BMI, ESS score, and the proportion of males were significantly higher in those needing high CPAP. They also have a lower MSLT mean. On logistic regression, the use of high CPAP was 5.90 times more frequent (95% confidence interval 2.67-13.1) in severe OSA patients after adjustment for the other variables. The area under the receiver operator curve was 72.4%, showing that the model was adequate. Severe OSA patients are much more likely to need high CPAP levels. However, because of the low positive predictive value (only 28.6%), the clinical value of such information is limited. ESS and MSLT did not increase the predictive value for the need for high CPAP.

Continuous positive airway pressure reduces nocturia in patients with obstructive sleep apnea

Objectives To examine whether treatment with continuous positive airway pressure (CPAP) reduces nocturia in patients with obstructive sleep apnea (OSA). Methods This prospective clinical study recruited patients referred to the Rambam Sleep Laboratory with suspected OSA. After polysomnography, those found to have no OSA were excluded from the study, and the remainder were treated with CPAP. Nocturia was assessed at four time points: baseline (average number of awakenings to urinate per night during 1 week at home before polysomnography); diagnostic night in the laboratory; CPAP titration in the laboratory; and after 1 to 3 months of stable CPAP treatment at home (average number of awakenings to urinate per night for 1 week). Results Ninety-seven patients (75 men and 22 women) completed the study. The mean ± SD age was 55 ± 12 years, body mass index was 33 ± 7 kg/m 2, and respiratory disturbance index was 34 ± 24/hr. The mean number of awakenings to void at home before CPAP was 2.5 ± 2.4 times/night; during CPAP, it was 0.7 ± 0.6 time/night ( P <0.001). A total of 73 patients reported improvement in nocturia. The mean number of awakenings to void in the laboratory was 1.1 ± 0.9 before CPAP, with a decrease to 0.5 ± 0.6 during CPAP ( P <0.001). Weak, but significant, correlations were found in the number of awakenings to void before treatment with the respiratory disturbance index ( r = 0.25, P = 0.01) and with minimal oxygen saturation ( r = −0.23, P = 0.02). Conclusions CPAP appears to be an effective treatment for nocturia associated with OSA.

Evaluation of Positive Airway Pressure Treatment for Sleep Related Breathing Disorders in Adults

Positive airway pressure (PAP) is used to treat obstructive sleep apnea (OSA), central sleep apnea (CSA), and chronic hypoventilation. This document provides a systematic analysis and grading of peer-reviewed, published clinical studies pertaining to application of PAP treatment in adults. The paper is divided into 5 sections, each addressing a series of questions. The first section deals with whether efficacy and/or effectiveness have been demonstrated for continuous PAP (CPAP) treatment based on a variety of parameters and the level of OSA severity. Next, CPAP titration conducted with full, attended polysomnography in a sleep laboratory is compared with titration done under various other conditions. The third section investigates what can be expected regarding adherence and compliance with CPAP treatment as measured by subjective and objective methods and what factors may influence these parameters. Side effects and the influence of other specific factors on efficacy, effectiveness and safety of CPAP therapy are evaluated in the fourth section. Finally, the use of bilevel PAP therapy is reviewed for both patients with OSA and those with other selected nocturnal breathing disorders. Each section also contains a brief summary and suggestions for future research.

Central sleep apnea, upper airway resistance and sleep

The question of why ‘central’ apnea is seen is a recurring theme. The term ‘diaphragmatic’ apnea is a better term than ‘central’ apnea as the latter indicates a dysfunction in the medulla, which is rare. The short response to the question raised is: ‘because the upper airway is not completely open’. This is a very common consequence when dental appliances are used to treat sleep-disordered breathing, but the response needs an explanation. Long-term studies on the outcome of dental appliances have mostly been poor. We reviewed 25 obstructive sleep apnea (OSA) patients monitored between 4 and 12 months post-fitting with commercially available dental appliances (unpublished observations). All subjects presented at least one standard deviation higher amount of cyclic alternating pattern (CAP), with higher CAP rate and higher amount of phase A2 [1]) and A3 [1]) than their ageand gender-matched controls, indicating persistence of some degree of sleep disturbance and instability of non-rapid eye movement (NREM) sleep in these patients. The reasons why dental appliances may not completely relieve a patient are multiple, from problems involving soft tissues attached to the maxilla and advancing the mandible, to a narrow airway at the base of the tongue and difficulty shifting the hyoid bone forward even with nasal continuous positive airway pressure (CPAP). The more interesting question is why we see persistence of diaphragmatic apneas with dental appliances, a similar finding sometimes when CPAP pressure level is not high enough when performing CPAP titration. During wakefulness, chemosensitivity plays little role in quiet breathing due to the non-specific stimuli that