Continuous positive airway pressure reduces daytime sleepiness in mild to moderate obstructive sleep apnoea: a meta-analysis

BACKGROUND: Obstructive sleep apnoea syndrome (OSAS) affects an estimated 2-4% of the middle aged population. Meta-analyses of randomised controlled trials have shown that the severe presentation of the syndrome (apnoea hypopnoea index (AHI) >30/hour) is effectively treated with continuous positive airway pressure (CPAP). Until recently there have been insufficient data to determine whether CPAP improves sleepiness in the larger subgroup with mild to moderate OSAS (AHI 5-30/hour). METHODS: A systematic search of Medline and a hand search identified seven randomised controlled trials where CPAP was compared with either a placebo or with conservative management in the treatment of mild to moderate OSAS (AHI 5-30/hour). All trials used the Epworth Sleepiness Scale (ESS), four used the Multiple Sleep Latency Test (MSLT), and three used the Maintenance of Wakefulness Test (MWT) to measure sleepiness. RESULTS: Meta-analyses indicated that CPAP significantly reduced subjective daytime sleepiness (ESS) by 1.2 points (95% CI 0.5 to 1.9, p = 0.001), improved objective daytime wakefulness (MWT) by 2.1 minutes (95% CI 0.5 to 3.7, p = 0.011), but did not affect objective daytime sleepiness (MSLT, mean benefit -0.2 minutes, 95% CI -1.0 to 0.6, p = 0.6). The two significant effects were small (effect size <0.30). CONCLUSIONS: CPAP elicits small improvements in subjective sleepiness and objective wakefulness in people with mild to moderate OSAS. However, the effects on sleepiness are of limited clinical significance.     

Evaluation of an auto-CPAP device for treatment of obstructive sleep apnoea

BACKGROUND—Auto-CPAPmachines used in the treatment of obstructive sleep apnoea (OSA) aredesigned to vary the treatment pressure automatically in order alwaysto apply the actually needed pressure. Consequently they should be ableto achieve at least identical therapeutic effects as conventionalconstant pressure CPAP with a lower mean treatment pressure. Thepresent study was designed to evaluate the therapeutic efficacy and thetreatment pressure of an auto-CPAP machine (REM+auto^®,SEFAM) in comparison with a conventional CPAP device.
METHODS—Following CPAPtitration, 16 patients with OSA were allocated to receive conventionalCPAP and auto-CPAP treatment under polysomnographic control in arandomised order. After each treatment the patients were asked toassess the therapy using a questionnaire; a vigilance test was alsocarried out and subjective daytime sleepiness was evaluated using theEpworth Sleepiness Scale (ESS).
RESULTS—The mean (SD)apnoea/hypopnoea index (AHI) during auto-CPAP treatment was comparablewith that during conventional CPAP treatment (4.2 (5.1) versus 3.6 (4.0)). Neither an analysis of sleep architecture nor the arousal index(7.4 (4.1) versus 7.0 (4.3)) revealed any significant differences.Daytime sleepiness measured with the ESS was also comparable (5.3 (3.4)versus 6.5 (4.2)). The vigilance test showed normal values after bothtreatments in all patients with no significant differences. The meanpressure during auto-CPAP treatment (8.1 (2.9) mbar), however, wassignificantly higher than that employed in conventional CPAP treatment(7.6 (2.7) mbar; mean difference 0.5 mbar; 95% CI 0.1 to 0.9 mbar;p<0.05).
CONCLUSIONS—Auto-CPAPwas equally as effective as conventional CPAP with respect totherapeutic efficacy. The aim of reducing the treatment pressure withauto-CPAP, however, was not achieved.

     

Randomised controlled crossover trial of humidified continuous positive airway pressure in mild obstructive sleep apnoea

BACKGROUND: It is unclear whether continuous positive airway pressure (CPAP), the treatment of choice for severe obstructive sleep apnoea (OSA), is effective at improving outcomes in mild OSA. METHODS: To help define the role of humidified CPAP in mild OSA, a randomised crossover study was undertaken of patients with an apnoea hypopnoea index (AHI) of 5-30/hour. Subjective sleepiness, objective wakefulness, mood, reaction time, and quality of life were measured at baseline, after 3 weeks treatment with humidified CPAP and 3 weeks sham CPAP (2 week washout). RESULTS: Twenty nine of 31 enrolled patients (age 25-67 years, seven women, mean (SD) body mass index 31.5 (6) kg/m2) completed the protocol. Humidified CPAP improved polysomnographic indices of OSA and Epworth Sleepiness Scale (2.4 points (95% CI 0.6 to 4.2)). Objective wakefulness (modified maintenance of wakefulness test) showed a trend towards improvement (5.2 minutes (95% CI -0.6 to 11)). Mood (Hospital Anxiety and Depression Scale), quality of life (SF 36, Functional Outcomes of Sleep Questionnaire), and reaction times (Psychomotor Vigilance Task) were not improved more than sham CPAP. Compliance with humidified and sham CPAP both averaged 4.9 hours/night. Placebo effects were evident in many outcomes and there was no clear treatment preference. CONCLUSIONS: Humidified CPAP improves subjective sleepiness and possibly objective wakefulness but not reaction times, quality of life, or mood. These results do not support the routine use of CPAP in all patients with mild OSA, but offers some support for the trialling of CPAP in those with severe sleepiness.     

Case-control study of 24 hour ambulatory blood pressure in patients with obstructive sleep apnoea and normal matched control subjects

BACKGROUND: There is considerable debate regarding the relationship between obstructive sleep apnoea (OSA) and hypertension. It is unclear whether OSA is an independent vascular risk factor as studies attempting to assess this association have produced conflicting results because of confounding variables such as upper body obesity, alcohol, and smoking. A case-control study of 24 hour ambulatory blood pressure was undertaken in patients with OSA and matched controls to assess whether OSA is an independent correlate of diurnal hypertension. METHODS: Forty five patients with moderate to severe OSA and excessive daytime sleepiness were matched with 45 controls without OSA in a sleep study. Matched variables included age, body mass index (BMI), alcohol, cigarette usage, treated hypertension, and ischaemic heart disease. Upper body obesity was compared by waist:hip and waist:height ratios; 24 hour ambulatory blood pressure recordings were performed (before treatment for OSA) in all subjects. RESULTS: Patients with OSA had significantly increased mean (SD) diastolic blood pressure (mm Hg) during both daytime (87.4 (10.2) versus 82.8 (9.1); p=0.03, mean difference 4.6 (95% CI 0.7 to 8.6) and night time (78.6 (9.3) versus 71.4 (8.0); p<0.001, mean difference 7.2 (95% CI 3.7 to 10.6)), and higher systolic blood pressure at night (119.4 (20.7) versus 110.2 (13.9); p=0.01, mean difference 9.2 (95% CI 2.3 to 16.1)). The nocturnal reduction in blood pressure ("dipping") was smaller in patients with OSA than in control subjects. CONCLUSIONS: Compared with closely matched control subjects, patients with OSA have increased ambulatory diastolic blood pressure during both day and night, and increased systolic blood pressure at night. The magnitude of these differences is sufficient to carry an increased risk of cardiovascular morbidity. The slight excess of upper body fat deposition in the controls may make these results conservative.     

Reduction in motor vehicle collisions following treatment of sleep apnoea with nasal CPAP

BACKGROUND—Patientswith untreated obstructive sleep apnoea (OSA) have increased motorvehicle collisions (MVCs). When successfully treated, they reportimproved driving and fewer mishaps, but there are few objective data toconfirm this. A study was therefore undertaken to examine actual MVCdata in a large group of patients with OSA before and after treatmentwith continuous positive airway pressure (CPAP) compared with a controlgroup matched for age, sex, and type of driver's licence (commercialor non-commercial).
METHODS—Two hundredand ten patients of mean (SD) age 52 (11) years, body mass index (BMI)35.5 (10) kg/m², apnoea/hypopnoea index (AHI) 54 (29)events/h were treated with CPAP for at least 3 years. MVC records wereobtained from the Ontario Ministry of Transportation (MTO) database forpatients and an equal number of randomly selected control drivers. MVC rates were compared for 3 years before and after CPAP therapy forpatients and for the corresponding time frames for controls.
RESULTS—Untreatedpatients with OSA had more MVCs than controls (mean (SD)MVCs/driver/year 0.18 (0.29) v 0.06 (0.17),p<0.001). Following CPAP treatment the number of MVCs/driver/year fellto normal (0.06(0.17)) while, in controls, the MVC rate was unchangedover time (0.06 (0.17) v 0.07 (0.18), p=NS).Thus, the change in MVCs over time between the groups was verysignificant (change = -0.12 (95% CI -0.17 to -0.06), p<0.001)).The MVC rate in untreated patients (n=27) remained high over time.Driving exposure was not different following CPAP.
CONCLUSIONS—The riskof MVCs due to OSA is removed when patients are treated with CPAP. Assuch, any restrictions on driving because of OSA could be safelyremoved after treatment.

     

Randomised placebo controlled trial of daytime function after continuous positive airway pressure (CPAP) therapy for the sleep apnoea/hypopnoea syndrome

BACKGROUND—Patients with the sleepapnoea/hypopnoea syndrome (SAHS) report improved sleepiness, cognitivefunction, and psychological well being after continuous positive airwaypressure (CPAP) therapy, and it is for these daytime features that CPAPis usually given. However, few randomised or controlled studies existon the effects of CPAP on daytime function.
METHODS—A prospective, randomised, single blind,placebo controlled, crossover trial of daytime function after CPAP wasconducted in 23 patients with SAHS, all with 15apnoeas+hypopnoeas/hour and 2 symptoms of SAHS. All patients spentfour weeks on CPAP therapy and four weeks on oral placebo treatment,following randomisation to treatment order. With ethics committeeapproval, patients were told the placebo tablet might improve upperairway function. Average effective CPAP use was monitored using hiddentime clocks. Assessments of objective and subjective sleepiness,symptoms, cognitive performance, and psychological well being wereperformed on the last day of each treatment and compared.
RESULTS—Objective sleepiness measured by sleeponset latency on the multiple sleep latency test improved with CPAP(mean difference from placebo +2.4 min, 95% CI 0.8 to 4.0; p<0.001)as did subjective sleepiness on the Epworth scale (mean difference -6,95% CI -3 to -9; p = 0.001). Symptom total score also fell with CPAP(mean difference -1.6, 95% CI -2.2 to -1.0; p<0.001). Nodeterminants of these changes with active treatment were identified,and no significant enhancements to cognitive function or psychosocial well being were found in this small sample.
CONCLUSIONS—These findings provide furtherevidence for clinically significant benefits to daytime function from CPAP.

     

Effect of CPAP therapy on daytime function in patients with mild sleep apnoea/hypopnoea syndrome

BACKGROUND: Continuous positive airway pressure (CPAP) is an effective treatment in patients with moderate and severe sleep apnoea/hypopnoea syndrome (SAHS), but the minimum illness severity at which patients obtain benefit from CPAP is unclear. A study was therefore undertaken to investigate whether CPAP improves symptoms and daytime function in patients with mild SAHS. METHODS: Sixteen consecutively recruited patients with mild SAHS (5.0-14.9 apnoeas + hypopnoeas per hour slept and two or more symptoms of SAHS) participated in a prospective placebo controlled randomised crossover trial to assess the effects of CPAP on symptoms and daytime function. Patients spent four weeks on placebo and four weeks on CPAP, undergoing assessments of sleepiness, symptoms, cognitive performance, and well being on the last day of each treatment. Data from the placebo and CPAP assessments were compared. RESULTS: The mean (SE) objective effective use of CPAP was 2.8 (0.7) hours per night. Significant improvements in symptom score (-1.7 (0.5), p < 0.01), mental flexibility (-14 (5) seconds, p = 0.02), and depression rating (-1.6 (0.8), p = 0.03) on CPAP were observed. However, no significant differences in subjective or objective sleepiness were found. Ten of the 16 patients preferred CPAP and opted to continue with this treatment, although this proportion was non- significant (p > 0.4). The eight patients with best CPAP use showed an additional CPAP related improvement in quality of life (-4.4 (1.8), p = 0.03). Those who complied better with CPAP therapy also had a higher average microarousal frequency (p < 0.01) and apnoea+hypopnoea index (p = 0.02) than the poorer compliers. CONCLUSIONS: The results of this study provide evidence for improvements in symptoms and daytime function for patients with mild SAHS treated with CPAP.


     

Compliance with CPAP therapy in patients with the sleep apnoea/hypopnoea syndrome.

BACKGROUND--Continuous positive airway pressure (CPAP) therapy is the treatment of choice for the sleep apnoea/hypopnoea syndrome. Compliance with this relatively obtrusive therapy has not been well studied. METHODS--Usage of CPAP was investigated in 54 patients with sleep apnoea/hypopnoea syndrome (median 36 (range 7-129) apnoeas + hypopnoeas/hour slept) over the first 1-3 months after starting CPAP therapy. In all cases CPAP usage was monitored by hidden time clocks that indicated for how long the machines were switched on--that is, the CPAP run time. In 32 patients the time at which the CPAP mask pressure was at the therapeutic level of CPAP pressure set for that patient--that is, the mask time--was also monitored. In all patients objective daytime sleepiness was assessed by multiple sleep latency before and after CPAP therapy. RESULTS--The mean (SE) nightly CPAP run time was 4.7 (0.4) hours. There was no correlation between run time and severity of the sleep apnoea/hypopnoea syndrome as assessed by apnoea + hypopnoea frequency or multiple sleep latency, and no correlation between CPAP usage and improvement in multiple sleep latency. Thirty two patients in whom mask time was recorded had therapeutic CPAP pressures for 89% (3%) of their CPAP run times. Patients who experienced side effects from CPAP used their CPAP machines significantly less than those who did not. CONCLUSIONS--Patients with sleep apnoea/hypopnoea syndrome used CPAP for less than five hours/night on average with no correlation between severity of sleep apnoea/hypopnoea syndrome and CPAP usage. Patients who complained of side effects used their CPAP therapy less. It is recommended that, as a minimum, CPAP run time should be regularly recorded in all patients receiving CPAP therapy.     

Effects of submental stimulation for several consecutive nights in patients with obstructive sleep apnoea.

BACKGROUND--It has previously been reported that short term submental stimulation can reduce the frequency of apnoea and improve sleep architecture in patients with obstructive sleep apnoea. The effects of submental stimulation during consecutive nights on apnoea or on daytime sleepiness have not, however, been studied. METHODS--Patients with obstructive sleep apnoea were studied by polysomnography on a control night, for five consecutive nights of submental stimulation, and on three following nights (n = 8). A multiple sleep latency test (MSLT) (n = 8) and measurement of the upper airway resistance (n = 5) were performed during the day after the polysomnographic study, on the control night, and on the fifth stimulation night. In an additional five patients with obstructive sleep apnoea, matched for age, sex, and weight, the effects of two nights of stimulation were examined for comparison. Submental stimulation began when an apnoea lasted for five seconds and stopped with the resumption of breathing as detected by oronasal flow. RESULTS--The apnoea index, the number of times per hour that SaO2 dropped below 85% (SaO2 < 85%/hour), and the total apnoea duration expressed as a percentage of total sleep time during stimulation nights decreased to approximately 50% of the corresponding values on the control night. This improvement persisted for at least two nights after the five consecutive stimulation nights, but not after the two consecutive stimulation nights. Sleep architecture and MSLT following the stimulation nights improved but upper airway resistance did not change. CONCLUSIONS--Submental stimulation for five consecutive nights in patients with obstructive sleep apnoea improved the breathing disturbance, sleep quality, and daytime sleepiness. The effect lasted for the following two nights, but did not completely abolish the sleep disordered breathing.     

Caffeine levels following treatment of obstructive sleep apnoea

BACKGROUND: Randomised trials show that treatment of obstructive sleep apnoea (OSA) with nasal continuous positive airway pressure (CPAP) greatly improves sleepiness and also lowers diurnal systemic blood pressures (BP). Such patients consume more coffee than controls (presumably to combat their sleepiness) and might reduce their consumption following effective treatment, thus lowering BP by this mechanism rather than via a direct effect of alleviating OSA. METHODS: Plasma caffeine levels before and after treatment with either therapeutic (n=52) or subtherapeutic (control, n=49) CPAP were measured in stored blood samples from a previous randomised controlled trial of CPAP for 4 weeks in patients with OSA. RESULTS: There was a small significant rise in caffeine levels when the two groups were analysed as a whole (p=0.02), but not individually. Despite the fall in sleepiness measured objectively in the therapeutic CPAP group, there was no difference in absolute (or change in) caffeine levels between the two groups (mean (SE) micro mol/l; therapeutic CPAP 9.2 (1.2), 10.2 (1.0), subtherapeutic 6.7 (0.9), 8.6 (0.9) before and after treatment, respectively). CONCLUSION: Reduced coffee consumption is unlikely to be the explanation for the falls in BP following treatment of OSA.     

Relationship between obstructive sleep apnoea, driving simulator performance, and risk of road traffic accidents

BACKGROUND: Obstructive sleep apnoea (OSA) has been shown to be associated with an increased risk of road traffic accidents (RTAs). Predicting the driving ability and risk of RTAs in an individual with OSA is difficult. On-road testing is the gold standard, but this is time consuming, expensive, and potentially dangerous. Simple computer based driving simulators have been developed to help determine driving ability. Although patients with OSA have been shown to perform poorly compared with matched controls, it is not known whether these simulators can predict those at most risk of accidents. In this study we evaluated whether data derived from a simple driving simulator provided information over and above that obtained from the history and a sleep study that might be useful for advising patients about driving. METHODS: We examined 150 patients admitted for routine sleep studies for investigation of OSA and snoring. Each patient performed a 20 minute driving simulation and completed a questionnaire regarding their driving history and experience. RESULTS: Logistic regression analysis was used to investigate factors associated with patients' performance on the simulator. It was found that patient characteristics, older age (OR 1.05, 95% CI 1.01 to 1.09, p<0.01), female sex (OR 9.32, 95% CI 1.09 to 79.4, p<0.04), and self-reported alcohol consumption (OR 1.04, 95% CI 1.01 to 1.07, p<0.01) had the greatest influence; however, the number of self-reported near miss accidents was independently associated with a poor performance (OR 2.62, 95% CI 1.00 to 6.88, p<0.05). A further logistic regression was used to investigate whether clinical history, sleep study results, and data from the driving simulator were useful in classifying patients with OSA as having had an RTA. The number of off-road events per hour on the simulator was independently associated with a history of previous RTA (OR 1.004, 95% CI 1.0004 to 1.008, p<0.03). The Epworth score was independently associated with episodes of falling asleep at the wheel (OR 1.21, 95% CI 1.12 to 1.31, p<0.00001) and near miss accidents (OR 1.15, 95% CI 1.07 to 1.23, p<0.0001). Using this model, 100% of patients who did not have an accident could be identified, but only 10% of those who did. CONCLUSIONS: Although factors not directly related to OSA influence performance on a driving simulator, there is an independent relationship between driving ability in patients with OSA and performance on a simple computer based simulator. When combined with clinical history, it is those not reporting hypersomnolence and not having off-road events on the simulator who appear to be at least risk of adverse driving events. Poor performance on the simulator, however, relates poorly to accident history. These data require confirmation in future studies before simple computer simulators can be used in clinical practice to advise whether an individual is safe to drive.     

Effect of CPAP on insulin resistance and HbA1c in men with obstructive sleep apnoea and type 2 diabetes

BACKGROUND: The effects of continuous positive airway pressure (CPAP) for obstructive sleep apnoea (OSA) on insulin resistance are not clear. Trials have found conflicting results and no appropriate control groups have been used. METHODS: Forty-two men with known type 2 diabetes and newly diagnosed OSA (>10 dips/h in oxygen saturation of >4%) were randomised to receive therapeutic (n = 20) or placebo CPAP (n = 22) for 3 months. Baseline tests were performed and repeated after 3 months. The study was double blind. RESULTS: Results are expressed as mean (SD). CPAP improved the Epworth sleepiness score significantly more in the therapeutic group than in the placebo group (-6.6 (4.5) vs -2.6 (4.9), p = 0.01). The maintenance of wakefulness test improved significantly in the therapeutic group but not in the placebo group (+10.6 (13.9) vs -4.7 (11.8) min, p = 0.001). Glycaemic control and insulin resistance did not significantly change in either the therapeutic or placebo groups: HbA1c (-0.02 (1.5) vs +0.1 (0.7), p = 0.7, 95% CI -0.6% to +0.9%), euglycaemic clamp (M/I: +1.7 (14.1) vs -5.7 (14.8), p = 0.2, 95% CI -1.8 to +0.3 l/kg/min(1000)), HOMA-%S (-1.5 (2.3) vs -1.1 (1.8), p = 0.2, 95% CI -0.3% to +0.08%) and adiponectin (-1.1 (1.2) vs -1.1 (1.3), p = 0.2, 95% CI -0.7 to +0.6 microg/ml). Body mass index, bioimpedance and anthropometric measurements were unchanged. Hours of CPAP use per night were 3.6 (2.8) in the treatment group and 3.3 (3.0) in the placebo group (p = 0.8). There was no correlation between CPAP use and the measures of glycaemic control or insulin resistance. CONCLUSION: Therapeutic CPAP does not significantly improve measures of glycaemic control or insulin resistance in men with type 2 diabetes and OSA.     

Nasal CPAP and weight loss in hypertensive patients with obstructive sleep apnoea.

BACKGROUND--The high prevalence of obstructive sleep apnoea (OSA) in patients with systemic hypertension and of hypertension in patients with OSA suggests a causal link between the two disorders. This study was carried out to determine whether nasal continuous positive airway pressure (CPAP) and weight loss affect daytime hypertension in OSA. METHODS--Sixty hypertensive patients with OSA took part in the study; 33 accepted nasal CPAP and used their machine for 5.7 (0.2) hours per night, and the remaining 27 patients refused nasal CPAP and upper airway surgery so the only therapeutic intervention was a recommendation of weight loss. A significant change in hypertension during follow up was defined as either a change in mean blood pressure of at least 10 mm Hg (or more than 8%) without a change in drug treatment, or a reduction in drug dosage with mean blood pressure within these limits. Weight loss was defined as a body mass index of at least 5% below the baseline value. RESULTS--After 512 (41) days, hypertension had become less severe in seven of 12 patients (58%) treated with weight loss only, in eight of 28 patients (29%) with nasal CPAP only, in two of five patients with nasal CPAP and weight loss, and in one of 15 patients without nasal CPAP or weight loss. Multivariate analysis of variance with the outcome of hypertension at follow up as the dependent variable revealed that only the percentage change in body mass index significantly contributed to the course of hypertension. CONCLUSION--The course of hypertension in OSA is more closely linked to weight loss than to elimination of sleep apnoea by nasal CPAP.     

Self reported snoring and daytime sleepiness in men aged 35-65 years.

BACKGROUND: It has been suggested that snoring alone, without conventional sleep apnoea or hypopnoea, may disrupt sleep and produce substantial daytime hypersomnolence. This study addresses this potential relationship. METHOD: Eight hundred and fifty men, aged 35-65 years, drawn from one general practice were visited at home and asked a range of questions potentially related to sleepiness, snoring, and sleep apnoea; these included inquiries about alcohol and cigarette consumption, nasal stuffiness, shift work, hypnotic or other drug use, and medical diagnoses. In addition, measurements of height, weight, and overnight arterial oxygen saturation were made. The relation between snoring and sleepiness, with allowance made for potentially confounding variables, including sleep apnoea, was assessed by multiple logistic regression. RESULTS: Positive answers to all questions about sleepiness were correlated significantly with self reported snoring. After potentially confounding variables and any sleep apnoea had been controlled for, positive answers to four questions about inappropriate drowsiness or sleepiness were independently related to snoring. For example, the odds ratio of admitting to "having almost had two or more car accidents while driving due to sleepiness" was 5.8 (95% confidence intervals: 2.7-12.5) in an "often" snorer. CONCLUSIONS: Although epidemiological associations such as this do not prove a causal relation, the study suggests that snoring (without classical sleep apnoea) may sometimes reduce sleep quality sufficiently to produce substantial daytime drowsiness.     

Health effects of identifying patients with undiagnosed obstructive sleep apnea in the preoperative clinic: a follow-up study

Background

Undiagnosed obstructive sleep apnea (OSA) is a highly prevalent breathing disorder. The purpose of this study was to determine the effects of preoperative screening and subsequent treatment for OSA on the health of patients.

Methods

We conducted a two-year follow-up study of patients previously enrolled in a large prospective study in which patients were given the STOP questionnaire for OSA screening (n?=?2,467). All patients who underwent a polysomnography were considered eligible (n?=?211) and were asked to complete a paper-based mailed questionnaire. The severity of OSA, comorbidities, and treatment modalities and their effects were evaluated from the returned questionnaire. Research ethics board approval was obtained and returning the questionnaire implied informed patient consent.

Results

The response rate was 67%. One hundred twenty-eight (82%) of the 156 patients who responded had OSA established by polysomnography. Among these 128 patients with OSA, 88 (69%) were prescribed continuous positive airway pressure (CPAP) therapy and 40 (31%) were prescribed other (non-CPAP) treatment. Among those 88 patients receiving CPAP, 40 (45%) were compliant and 48 (55%) were non-compliant. The CPAP compliant patients had a greater reduction in medication for comorbidities than the CPAP non-compliant or the other treatment group (38% vs 3% vs 0%, respectively; P?<?0.001). A significant improvement in snoring, sleep quality, and daytime sleepiness was reported by CPAP compliant users compared with CPAP non-compliant or other treatment groups (P?<?0.001).

Conclusion

The preoperative patients who were identified to have OSA and were compliant with CPAP use may have health benefits in terms of improved snoring, sleep quality, and daytime sleepiness. Timely diagnosis and treatment compliance may reduce symptoms of OSA and severity of associated comorbidities along with a reduction in medications.     

Nasal CPAP reduces systemic blood pressure in patients with obstructive sleep apnoea and mild sleepiness

BACKGROUND: A randomised controlled study was undertaken to examine the effect of nasal continuous positive airway pressure (CPAP) on 24 hour systemic blood pressure (BP) in patients with obstructive sleep apnoea (OSA). METHODS: Patients were fitted with an ambulatory BP measuring device as outpatients during normal activities and recorded for 24 hours before starting therapeutic or subtherapeutic (4 cm H(2)O) CPAP treatment. BP monitoring was repeated before completion of 12 weeks of treatment. The primary end point was the change in 24 hour mean BP. RESULTS: Twenty three of 28 participants in each treatment arm completed the study. There was no significant difference between the two groups in age, body mass index, Epworth Sleepiness Score, apnoea-hypopnoea index, arousal index, and minimum Sao(2). Twenty four patients were hypertensive. The pressure in the therapeutic CPAP group was 10.7 (0.4) cm H(2)O. CPAP usage was 5.1 (0.4) and 2.6 (0.4) hours/night for the therapeutic and subtherapeutic CPAP groups, respectively (p<0.001). After 12 weeks of treatment there were significant differences between the two CPAP groups in mean (SE) changes in 24 hour diastolic BP (-2.4 (1.2) v 1.1 (1.0) mm Hg (95% CI -6.6 to -0.5), p = 0.025); 24 hour mean BP (-2.5 (1.3) v 1.3 (1.1) mm Hg (95% CI -7.2 to -0.2), p = 0.037); sleep time systolic BP (-4.1 (2.1) v 2.2 (1.8) mm Hg (95% CI -11.8 to -0.7), p = 0.028); and sleep time mean BP (-3.6 (1.7) v 1.3 (1.4) mm Hg (95% CI -9.2 to -0.4), p = 0.033). CONCLUSIONS: Compared with subtherapeutic CPAP, 12 weeks of treatment with therapeutic CPAP leads to reductions in 24 hour mean and diastolic BP by 3.8 mm Hg and 3.5 mm Hg, respectively, in mildly sleepy patients with OSA.     

Comparison of three ways to determine and deliver pressure during nasal CPAP therapy for obstructive sleep apnoea

BACKGROUND: The simplest method of initiating and maintaining therapeutic continuous positive airways pressure (CPAP) therapy for obstructive sleep apnoea (OSA) has not been established. METHODS: Ninety eight subjects with OSA requiring CPAP treatment (more than 10 dips in oxygen desaturation of >4% per hour of sleep study and Epworth Sleepiness Score (ESS) >9) were randomised prospectively to three different methods of CPAP delivery for 6 months: (1) autotitration pressure throughout; (2) autotitration pressure for 1 week followed by fixed pressure (95th centile) thereafter; and (3) fixed pressure determined by algorithm (based on neck size and dip rate). Patients and investigators were blind to group allocation. One week after initiation the patients were routinely reviewed by sleep nurses. Study assessments took place before starting CPAP treatment and 1 and 6 months after to assess ESS, maintenance of wakefulness test, 24 hour blood pressure, general health (SF-36), and sleep apnoea related quality of life. CPAP internal monitoring data were also collected. RESULTS: There were no significant differences in any of the outcome measures or CPAP monitoring data between the three groups. The 95th centile CPAP pressures delivered in the 6 month and 1 week autotitration groups were higher than in the algorithm group, but the median pressures were lowest in the 6 month autotitration group. CONCLUSIONS: The method of determining CPAP pressure for treatment of moderate to severe OSA makes no significant difference to clinical outcome measures. The autotitration CPAP machine used has no advantage in this setting over simpler methods of pressure determination.     

Automatic nasal continuous positive airway pressure titration in the laboratory: patient outcomes

BACKGROUND: Manual titration of nasal continuous positive airway pressure (NCPAP) treatment for obstructive sleep apnoea (OSA) is time consuming and expensive. There are now "intelligent" NCPAP machines that try to find the ideal pressure for a patient by monitoring a combination of apnoeas, hypopnoeas, inspiratory flow limitation, and snoring. Although these machines usually find similar pressures to skilled technicians, it is not clear if their use in the sleep laboratory influences subsequent acceptance by patients. This study addresses this question. METHODS: One hundred and twenty two patients undergoing a trial of NCPAP were randomly allocated to either manual or automatic (Horizon, DeVilbiss) titration of pressure during their first night on NCPAP in a hospital sleep laboratory. The primary outcome (available on 112 patients) was the acceptance of NCPAP or otherwise six weeks following the initial titration night. Baseline indicators of severity were compared between the groups, as were the pressures selected and the subsequent improvement in the sleepiness of the patients. RESULTS: The initial severity of OSA was not significantly different in the two groups and the mean (SD) NCPAP pressures were similar (manual 8.7 (2.5) cm H2O, automatic 8.2 (2.1) cm H2O). The percentage of patients successfully established on CPAP at six weeks was 64% and 73% for the manual and automatic groups, respectively; 13% and 2%, respectively, in the manual and automatic groups had given up completely (p < 0.05), and there were about equal numbers (23% versus 25%) in the two groups who were still undecided. CONCLUSIONS: The substitution of automatic NCPAP titration for manual titration during the first night of NCPAP in patients with OSA does not reduce the number accepting the treatment at six weeks and may slightly improve it. This has important cost saving potential.


     

A short-term controlled trial of an adjustable oral appliance for the treatment of mild to moderate obstructive sleep apnoea

BACKGROUND: Although oral appliances are effective in some patients with obstructive sleep apnoea (OSA), they are not universally effective. A novel anterior mandibular positioner (AMP) has been developed with an adjustable hinge that allows progressive advancement of the mandible. The objective of this prospective crossover study was to compare efficacy, side effects, patient compliance, and preference between AMP and nasal continuous positive airway pressure (nCPAP) in patients with symptomatic mild to moderate OSA. METHODS: Twenty four patients of mean (SD) age 44.0 (10.6) years were recruited with a mean (SD) body mass index of 32.0 (8.2) kg/m2, Epworth sleepiness score 10.7 (3.4), and apnoea/hypopnoea index 26.8 (11.9)/hour. There was a two week wash-in and a two week wash-out period and two treatment periods (AMP and nCPAP) each of four months. Efficacy, side effects, compliance, and preference were evaluated by a questionnaire and home sleep monitoring. RESULTS: One patient dropped out early in the study and three refused to cross over so treatment results are presented on the remaining 20 patients. The apnoea/hypopnoea index (AHI) was lower with nasal CPAP 4.2 (2.2)/hour than with the AMP 13.6 (14.5)/hour (p < 0.01). Eleven of the 20 patients (55%) who used the AMP were treatment successes (reduction of AHI to < 10/hour and relief of symptoms), one (5%) was a compliance failure (unable or unwilling to use the treatment), and eight (40%) were treatment failures (failure to reduce AHI to < 10/hour and/or failure to relieve symptoms). Fourteen of the 20 patients (70%) who used nCPAP were treatment successes, six (30%) were compliance failures, and there were no treatment failures. There was greater patient satisfaction with the AMP (p < 0.01) than with nCPAP but no difference in reported side effects or compliance. CONCLUSIONS: AMP is an effective treatment in some patients with mild to moderate OSA and is associated with greater patient satisfaction than nCPAP.