Cytokine gene polymorphisms in obstructive sleep apnoea/hypopnoea syndrome.

OBJECTIVE: The pro-inflammatory cytokines, TNF-α, IL-6, and IL-8 are elevated in obstructive sleep apnoea/hypopnoea syndrome (OSAHS). Cytokine gene interactions are complex and haplotype analysis may be more informative. We hypothesized that the effects of TNF-α in OSAHS might be due to linkage disequilibrium of the TNF-α (-308A) single nucleotide polymorphism (SNP) with other polymorphisms within the TNF-α gene, and that predisposition to elevated IL-6 and IL-8 levels in OSAHS might be attributable to pro-inflammatory IL-6 and IL-8 gene promoter polymorphisms. METHOD: 173 subjects were classified as having definite OSAHS or not on the basis of apnoea-hypopnoea frequency, sex, age, and symptoms. Population controls comprised 192 random UK blood donors. Genotyping was undertaken for the TNF-α promoter polymorphisms (-1031, -863, -857, -238), two lymphotoxin-α polymorphisms (intron 1 and Thr60Asn), the pro-inflammatory IL-6 gene promoter polymorphism (-174), and IL-8 gene promoter polymorphisms (-251; -781). RESULTS: There was no significant difference between groups re: genotype/allelic frequency in the genes investigated. Association between disease status and the TNF-α alleles independently (TNF-103, TNF-803, TNF-857, TNF-238) with five haplotypes of TNF-α was not significant (p > 0.05). There was no difference in allelic or genotypic frequencies between obese and non-obese subjects with OSAHS. The TNF-α (-863A) allele alone, was significantly associated with obesity (OR 2.4; CI95% 1.1-5; p = 0.025). CONCLUSION: Only the TNF-α (308A) SNP appears to be significantly associated with OSAHS. The impact of cytokine gene polymorphisms on phenotypic expression of inflammation in OSAHS is likely to be complex.

Narcolepsy and sleep-disordered breathing.

BACKGROUND AND PURPOSE: There is a high incidence of sleep-disordered breathing (SDB) in narcoleptic patients. Some narcoleptics with SDB may benefit from treatment with continuous positive airway pressure therapy (CPAP). The aim of this study was to examine the prevalence of SDB in narcoleptics referred to a tertiary sleep disorders clinic and assess the effectiveness of CPAP as adjunctive therapy. METHODS: A retrospective review of patients meeting ICSD-2 criteria for the diagnosis of narcolepsy from 2000 to 2009. RESULTS: One hundred and two patients (61 women) with narcolepsy were included in the study. Twenty-nine (29) patients (eight women, 21 men) were diagnosed with obstructive sleep apnoea-hypopnoea syndrome (OSAHS) of whom 26 commenced CPAP therapy with 11 patients concurrently treated with stimulants. Patients with narcolepsy and OSAHS were older (P = 0.009) and heavier (BMI, 29.6 ± 4.8 vs. 27.3 ± 6, P = 0.042), but their ESS did not differ from patients with narcolepsy alone. Patients treated with both CPAP and stimulants were younger (P = 0.008) and less obese (BMI, 29.1 ± 4.6 vs. 30.4 ± 5.4, P = 0.044) with higher apnoea-hypopnoea index (36.15 ± 21.9 vs. 31.5 ± 16.7, P = 0.03) than those treated with CPAP alone. The ESS of CPAP-treated patients improved during follow-up (19 ± 3.6 vs. 15.8 ± 4.5, P = 0.006), but BMI increased (30.6 ± 5 vs. 31.7 ± 5.6, P = 0.05). The use of stimulants did not seem to improve on the effectiveness of CPAP. CONCLUSION: Coexisting SDB is common in narcoleptics (28.5%). CPAP therapy in narcoleptics with OSAHS remains a useful second-line adjunct to standard therapy.

Diagnosing narcolepsy with cataplexy on history alone: challenging the International Classification of Sleep Disorders (ICSD-2) criteria.

BACKGROUND AND PURPOSE: The second version of the International Classification of Sleep Disorders suggests narcolepsy with cataplexy can be diagnosed on history alone. PATIENTS: Five patients with a history supportive of narcolepsy/cataplexy. METHOD: Case review following clinical investigation. RESULTS: None of the five patients had a diagnosis of narcolepsy/cataplexy on the basis of objective testing using polysomnography (PSG) and multiple sleep latency testing (MSLT). CONCLUSION: PSG and MSLT should always be used in conjunction with a comprehensive history taken by an experienced sleep physician to support a diagnosis of narcolepsy with cataplexy and to exclude other conditions that may mimic narcolepsy.

Continuous positive airway pressure improves vascular function in obstructive sleep apnoea/hypopnoea syndrome: a randomised controlled trial.

BACKGROUND: The obstructive sleep apnoea/hypopnoea syndrome (OSAHS) is associated with hypertension and increased cardiovascular risk, particularly when accompanied by marked nocturnal hypoxaemia. The mechanisms of these associations are unclear. We hypothesised that OSAHS combined with severe nocturnal hypoxaemia causes impaired vascular function that can be reversed by continuous positive airways pressure (CPAP) therapy. METHODS: We compared vascular function in two groups of patients with OSAHS: 27 with more than 20 4% desaturations/h (desaturator group) and 19 with no 4% and less than five 3% desaturations/h (non-desaturator group). In a randomised, double blind, placebo controlled, crossover trial, the effect of 6 weeks of CPAP therapy on vascular function was determined in the desaturator group. In all studies, vascular function was assessed invasively by forearm venous occlusion plethysmography during intra-arterial infusion of endothelium dependent (acetylcholine 5-20 microg/min and substance P 2-8 pmol/min) and independent (sodium nitroprusside 2-8 microg/min) vasodilators. RESULTS: Compared with the non-desaturator group, patients with OSAHS and desaturations had reduced vasodilatation to all agonists (p = 0.007 for all). The apnoea/hypopnoea index and desaturation frequency were inversely related to peak vasodilatation with acetylcholine (r = -0.44, p = 0.002 and r = -0.43, p = 0.003) and sodium nitroprusside (r = -0.42, p = 0.009 and r = -0.37, p = 0.02). In comparison with placebo, CPAP therapy improved forearm blood flow to all vasodilators (p = 0.01). CONCLUSIONS: Patients with OSAHS and frequent nocturnal desaturations have impaired endothelial dependent and endothelial independent vasodilatation that is proportional to hypoxaemia and is improved by CPAP therapy. Impaired vascular function establishes an underlying mechanism for the adverse cardiovascular consequences of OSAHS.

Sleep-disordered breathing after stroke: a randomised controlled trial of continuous positive airway pressure.

BACKGROUND: Sleep-disordered breathing (SDB) is common after stroke, but it is unclear whether it should be treated. OBJECTIVE: To conduct a randomised controlled trial of continuous positive airway pressure (CPAP) after stroke. METHODS: Patients with stroke with > or = 30 apnoeas and hypopnoeas per hour ((A+H)/h) with predominant obstructive sleep apnoea or hypopnoea were randomised to either CPAP treatment or conservative treatment for 8 weeks. Outcomes were measured blind to treatment allocation at 8 weeks and 6 months after the stroke. The primary outcome was physical function on the Nottingham Extended Activities of Daily Living Scale. RESULTS: Of 658 patients with stroke screened, only 71 (10.7%) were eligible and consented to a sleep study 14-19 days after stroke. 66 patients completed the sleep study (21 women; mean age 72 years), 33 (50%) had > or = 30 (A+H)/h that were predominantly obstructive. 15 were randomised to CPAP treatment and 15 to conventional treatment. Despite intensive efforts, objective use of CPAP was poor, averaging 1.4 h a night. CPAP treatment resulted in no significant improvements (p>0.1) in the primary outcome or in neurological function or sleepiness, and in poorer health status on some measures. CONCLUSIONS: This trial showed no benefit from CPAP treatment, the relevance of the observed detrimental effects is questionable. Even in our highly selected patients with stroke, use of CPAP was poor. At present, CPAP treatment should be advocated for patients with stroke only if they have symptoms of SDB.

Sleep-disordered breathing and upper airway size in pregnancy and post-partum.

Sleep-disordered breathing and snoring are common in pregnancy. The aim of this study was to determine whether pregnancy was associated with upper airway narrowing. One-hundred females in the third trimester of pregnancy were recruited and 50 agreed to be restudied 3 months after delivery. One-hundred nonpregnant females were also recruited. Upper airway dimensions were measured using acoustic reflection. Snoring was less common in nonpregnant (17%) than pregnant females (41%; odds ratio (OR) 3.34; 95% confidence interval (CI) 1.65-6.74) and returned to nonpregnant levels after delivery (18%; OR 0.15; 95% CI 0.06-0.40). Pregnant females had significantly smaller upper airways than nonpregnant females at the oropharyngeal junction when seated (mean difference 0.12; 95% CI 0.008-0.25), and smaller mean pharyngeal areas in the seated (mean difference 0.14; 95% CI 0.001-0.28), supine (mean difference 0.11; 95% CI 0.01-0.22) and lateral postures (mean difference 0.13; 95% CI 0.02-0.24) compared with the nonpregnant females. Pregnant females had smaller mean pharyngeal areas compared with post-partum in the seated (mean difference 0.18; 95% CI 0.02-0.32), supine (mean difference 0.20; 95% CI 0.06-0.35) and lateral postures (mean difference 0.26; 95% CI 0.12-0.39). In conclusion, this study confirmed increased snoring and showed narrower upper airways during the third trimester of pregnancy.

Tumour necrosis factor-alpha (-308) gene polymorphism in obstructive sleep apnoea-hypopnoea syndrome.

Patients with obstructive sleep apnoea-hypopnoea syndrome (OSAHS) have elevated circulating levels of tumour necrosis factor (TNF)-alpha. The hypothesis in this study was that OSAHS might be associated with the TNF-alpha (-308A) gene polymorphism, which results in increased TNF-alpha production. This hypothesis was examined in OSAHS patients, their siblings and population controls. A total of 206 subjects were recruited. All underwent sleep studies and clinical review, and were subsequently classified as having OSAHS or not depending on apnoea-hypopnoea frequency, sex, age and symptoms. All subjects had blood collected and genotyping was performed on DNA extracted from peripheral leukocytes. Some 192 random UK blood donors were used as population controls. The results demonstrated a significant association for TNF-alpha (-308A) allele carriage with OSAHS (OR=1.8; 95% Confidence interval: 1.18-2.75) when compared with population controls. Siblings with OSAHS were significantly more likely to carry the TNF-alpha (-308A) allele. In addition, 21 pairs of male siblings discordant for carriage of the -308A allele showed a significant level of discordance for the OSAHS phenotype. In conclusion, this study demonstrates an association of tumour necrosis factor-alpha (-308A) carriage with obstructive sleep apnoea-hypopnoea syndrome, suggesting that inflammation may be implicated in the pathogenesis of this condition.

Night-to-night variation of the oxygen desaturation index in sleep apnoea syndrome.

The current study investigated the night-to-night variability and diagnostic accuracy of the oxygen desaturation index (ODI), as measured by ambulatory monitoring, in the diagnosis of mild and moderate obstructive sleep apnoea-hypopnoea syndrome. To assess the variability of the ODI, 35 patients were monitored at home during 7 consecutive nights by means of a portable recording device, the MESAM-IV. The ODI variability factor and the influence of age, body mass index (BMI), alcohol, and body position were assessed. Furthermore, the diagnostic accuracy of the MESAM-IV was measured by comparison with polysomnographical outcomes in 18 patients. During home recording, the median ODI was 10.9 (interquartile range: 5.8-16.1) across the patients. Although the reliability of the ODI was adequate, the probability of placing the patient in the wrong severity category (ODI < or =15 or ODI >15) when only one single recording was taken is 14.4%. ODI variability was not significantly influenced by age, BMI, time spent in a supine position, or mild dosages of alcohol. A good correlation was found between the apnoea-hypopnoea index and the ODI. In conclusion, the findings suggest that the diagnostic accuracy of the MESAM-IV is strong, since the oxygen desaturation index is correlated with the apnoea-hypopnoea index. In most obstructive sleep apnoea-hypopnoea syndrome patients, oxygen desaturation index variability is rather small, and screening could be reliably based on single 1-night recordings.

Can psychological factors help us to determine adherence to CPAP? A prospective study.

The present study objective was to establish whether pretreatment social cognitive variables may contribute to the explanation of variance in adherence to continuous positive airway pressure (CPAP) treatment for patients with obstructive sleep apnoea/hypopnoea syndrome (OSAHS). A total of 119 of 180 consecutive OSAHS patients were recruited to the study prior to initial CPAP titration. Patients completed psychological measures of health value, health locus of control (incorporating internality, chance, powerful others) and self-efficacy prior to CPAP titration. Objective adherence data were measured by CPAP unit time clocks and collected at 3-month follow-up. Average nightly use was calculated over this period. Logistic regression of prospective predictors of adherence produced a model comprising psychological (health value, internality, powerful others), as well as clinical variables (Epworth score, body mass index, apnoea/hypopnoea index, CPAP pressure). This model explained 24% of the variance in CPAP use, and correctly identified 75% of adherers and 53% of nonadherers. Although the psychological variables explained only a small amount of the overall variance in adherence behaviour, this result provides further support for the hypothesis that psychological variables contribute, in part, to continuous positive airway pressure adherence. Future research should focus on highlighting discrete variables, which may helpfully inform psychologically based interventions aimed at improving the use of continuous positive airway pressure by patients with obstructive sleep apnoea/hypopnoea syndrome at risk of discontinuance.

Sleep. 4: Sleepiness, cognitive function, and quality of life in obstructive sleep apnoea/hypopnoea syndrome.

Sleepiness, cognitive performance, and quality of life are overlapping aspects of daytime function that may be affected in patients with obstructive sleep apnoea/hypopnoea syndrome. The evidence is compatible with hypotheses that these deficits are reversible with treatment, particularly for patients with severe disease.

Is there a familial association between obstructive sleep apnoea/hypopnoea and the sudden infant death syndrome?

BACKGROUND: One postulated cause of the sudden infant death syndrome (SIDS) is upper airway obstruction during sleep. Several studies have suggested that SIDS may be more common in families with obstructive sleep apnoea/hypopnoea syndrome (OSAHS), but were limited by uncertainty as to whether the deaths were due to SIDS. We have tested the hypothesis that parents of true SIDS cases have an increased frequency of apnoeas and hypopnoeas during sleep. METHODS: The parents of 269 rigorously determined SIDS cases were invited for single night polysomnography and daytime ventilatory control measurement. RESULTS: Parents of 198 cases were identified but 152 did not respond or declined. Fifty five parents of 34 cases were studied and matched for age, height, and weight to 55 subjects from general practice registers. There was no difference in breathing during sleep between the parents of SIDS cases (median (IQR) 5.9 (3.2, 10.7) apnoeas+hypopnoeas/h) and controls (6.7 (4.0, 12.2) apnoeas+hypopnoeas/h; p = 0.47), but the SIDS parents had lower minimum nocturnal oxygen saturation (median (IQR) 92 (89, 93)%) than controls (92 (90, 94)%; p = 0.048). There were no major differences in control of breathing when awake between SIDS parents and controls. CONCLUSIONS: These results provide no evidence to support an association between SIDS and OSAHS. However, the minor impairment of oxygenation during sleep in SIDS parents requires further study.

Spectral oscillations of RR intervals in sleep apnoea/hypopnoea syndrome patients.

A recent study has shown that daytime heart rate variability is reduced in obstructive sleep apnoea/hypopnoea syndrome (OSAHS) patients. In the present study, the hypothesis was that sympathovagal balance around apnoeas/hypopnoeas and nocturnal autonomic activity are altered in OSAHS patients. Frequency- and time-domain analyses of RR intervals were performed to monitor sympathovagal activity noninvasively. Fourteen untreated OSAHS patients and seven healthy subjects underwent overnight polysomnography. Low (LF) and total (TF) frequency power increased 2 min around the end of apnoeas/hypopnoeas (LF 229+/-38 ms2 TF 345+/-45 ms2) compared with undisturbed sleep (LF 106+/-18 ms2, TF 203+/-23 ms2). The increase in high frequency (HF) power was not significant. LF increase was proportionally higher than the HF increase (normalised LF (LFn) 67+/-1 units, normalised HF (HFn) 33+/-1 units) compared with undisturbed sleep (LFn 52+/-2 units, HFn 48+/-2 units). RR duration did not change around apnoeas/hypopnoeas (RR 904+/-28 ms). The LF and TF power increase was greater around arousal-inducing (LF 260+/-45 ms2 TF 390+/-65 ms2) compared with self-terminating (LF 161+/-31 ms2, TF 249+/-40 ms2) apnoeas/hypopnoeas; the LF and LFn increases were significant in both groups compared with undisturbed sleep and HF power differences were nonsignificant. RR intervals were longer around self-terminating apnoeas/hypopnoeas (RR 914+/-29 ms); the differences were not significant compared with undisturbed sleep. RR interval spectral power was not influenced by the event type. RR duration decreased (912+/-28 ms) and LF, HF and TF power increased (LF 111+/-16 ms2 , HF 62+/-6 ms , TF 173+/-21 ms2) across patients, compared with healthy controls (RR 1138+/-91 ms, LF 57+/-3 ms2, HF 35+/-3 ms2, TF 91+/-6 ms2). LFn and HFn did not change significantly. Sympathetic activity increases around apnoeas/hypopnoeas. The recurrent nocturnal fluctuations of sympathovagal balance and the overall increase of nocturnal autonomic activity may be of importance in the development of cardiovascular disease in sleep apnoea patients.

Assessment of thoracoabdominal bands to detect respiratory effort-related arousal.

It would be helpful to be able to identify respiratory effort-related arousal (RERA) without needing to measure oesophageal pressure. Thoracoabdominal movements yield an indirect flow measurement from which reduction of amplitude and alteration of the inspiratory flow curve can be detected. The aim of this study was to evaluate the accuracy of using the shape and amplitude of signals from thoracoabdominal bands (inductance plethysmography) to detect RERAs. Altogether, 94 subjects suspected of having sleep apnoea but with an apnoea/hypopnoea index < or = 10 in full polysomnography with oesophageal pressure were studied. A routine polysomnographical analysis was carried out. The polysomnographies were then reanalysed at random to determine which of the identified arousals were due to RERA, as determined either by oesophageal pressure or by induction bands without an oesophageal pressure signal. Altogether, 14,617 arousals were analysed. The sensitivity and specificity to find RERA (arousal by arousal) from bands versus oesophageal pressure were both 94%. The average difference of RERA index between oesophageal pressure and bands was -0.6. The correlation between RERA index determined by oesophageal pressure and bands was 0.98. To evaluate the intra and interobserver agreement, 1183 arousals were additionally analysed. The intraobserver agreement was 91% for RERAs by oesophageal pressure and 80% by bands. The interobserver agreement was 89% by oesophageal pressure and 85% by bands. The thoracoabdominal bands can be used to identify respiratory effort-related arousal (obstructive events not detected by thermistor) with similar efficacy to oesophageal pressure measurement. Since bands are routinely used in most polysomnographies, they can be used as the usual method to detect respiratory effort-related arousal, using a thermistor to evaluate apnoeas and hypopnoeas or as a complement to other methods, such as nasal cannula, which can detect apnoeas, hypopnoeas and respiratory effort-related arousal.

Evaluation of a portable device for diagnosing the sleep apnoea/hypopnoea syndrome.

Waiting times for hospital-based monitoring of the obstructive sleep apnoea/hypopnoea syndrome (OSAHS) are rising. This study tested whether Embletta, a new portable device, may accurately diagnose OSAHS at home. A synchronous comparison to polysomnography was performed in 40 patients and a comparison of home Embletta studies with in-laboratory polysomnography was performed in 61 patients. In the synchronous study, the mean difference (polysomnography-Embletta) in apnoeas+hypopnoeas (A+H) x h(-1) in bed was 2 h(-1). In comparison to the apnoea/ hypopnoea index (AHI) x h(-1) slept, the Embletta (A+H) x h(-1) in bed differed by 8 x h(-1). These data were used to construct diagnostic categories in symptomatic patients from their Embletta results: "OSAHS" (> or = 20 (A+H) x h(-1) in bed), "possible OSAHS" (10-20 (A+H) x h(-1) in bed) or "not OSAHS" (<10 (A+H) x h(-1) in bed). In the home study, the mean difference in (A+H) x h(-1) in bed was 3 x h(-1). In comparison to the polysomnographic AHI x h(-1) slept, the Embletta (A+H) x h(-1) in bed differed by 6 +/- 14 x h(-1). Using the above classification, all nine patients categorised as not OSAHS had AHI < 15 x h(-1) slept on polysomnography and all 23 with OSAHS on Embletta had an AHI > or = 15 on polysomnography, but 18 patients fell into the possible OSAHS category potentially requiring further investigation and 11 home studies failed. Most patients were satisfactorily classified by home Embletta studies but 29 out of 61 required further investigation. The study suggested a 42% saving in diagnostic costs over polysomnography if this approach were adopted.

Electroencephalographic spectral analysis: detection of cortical activity changes in sleep apnoea patients.

There are no visible electroencephalographic (EEG) changes at the termination of some apnoeas and hypopnoeas. This study tests the hypothesis that cortical activity fluctuates at apnoea/hypopnoea termination, despite the lack of visible changes. To detect these changes, EEG spectral analysis was performed and centred around the end of apnoeas/hypopnoeas in 15 sleepy patients. Ten second windows were applied and comparisons were conducted between the normalised power of the same frequency bands before and after termination of each apnoea/hypopnoea. Comparisons were performed within patients between apnoeas/hypopnoeas and periods of undisturbed sleep as well as between patients and healthy subjects during sleep. Normalised theta power (4-8 Hz) decreased significantly at apnoea/hypopnoea termination. No significant changes were found between consecutive periods of undisturbed sleep across the 15 patients. During nonrapid eye movement sleep, changes were detected irrespective of arousal visibility. During rapid eye movement sleep, nonarousal apnoeas/hypopnoeas were not accompanied by any significant spectral power changes. Theta power was significantly lower across patients compared to healthy subjects (p=0.03) and was correlated to the apnoea/hypopnoea index (rho=0.6, p=0.008). The authors conclude that electroencephalographic spectral analysis improves detection of changes at apnoea/hypopnoea termination. Further validation is needed to determine whether it improves correlation between nocturnal measures and daytime symptoms.

Arousability in sleep apnoea/hypopnoea syndrome patients.

Sleep disruption and daytime sleepiness in obstructive sleep apnoea/hypopnoea syndrome (OSAHS) patients result from recurrent apnoeas/hypopnoeas and arousals from sleep. Around 30% of apnoeas/hypopnoeas are not terminated by visible cortical arousals. The current authors tested the hypotheses that arousal induction is linked to sleep stage, oxygen desaturation, event type, event duration and time of occurrence during the night. Fifteen patients with OSAHS of varying severity were studied and all their apnoeas/hypopnoeas were evaluated. Eight of 15 patients had apnoeas/hypopnoeas in all sleep stages, and all their 610 apnoeas/hypopnoeas were analysed in the between stages comparison; data from all 15 patients were included in other comparisons. Thirty-four per cent of apnoeas/hypopnoeas during slow wave sleep (SWS) were associated with arousal, significantly less than the 77% during nonrapid eye movement (NREM) 1 and 2 and 62% during rapid eye movement (REM) sleep. Arousal induction was not affected by oxygen desaturation, event type, duration or time of the night. The apnoeal/hypopnoea index was 39 x h(-1) in REM 1 and 2, significantly higher compared to 17 x h(-1) in REM or to 11 x h(-1) in SWS sleep. In conclusion, apnoeas/hypopnoeas in slow wave sleep are associated with fewer cortically apparent, visually detected arousals.

Randomised controlled trial of continuous positive airway pressure and standard oxygen therapy in acute pulmonary oedema; effects on plasma brain natriuretic peptide concentrations.

AIMS: The study aim was to compare the effects of continuous positive airway pressure (CPAP) on clinical outcomes and plasma neurohormonal concentrations in patients with acute pulmonary oedema. METHODS AND RESULTS: In addition to standard therapy, 58 consecutive patients were randomized to receive 60% inhaled oxygen with or without CPAP at 7.5 cmH(2)O pressure. Clinical variables, symptoms and oxygenation were monitored and plasma epinephrine, norepinephrine and brain natriuretic peptide (BNP) concentrations estimated at 0, 1, 6 and 24 h. CPAP was associated with less breathlessness at 1 h (P<0.001), no treatment failures and more rapid resolution in respiratory rate (P<0.001), heart rate (P<0.001) and acidosis (P<0.005). Length of hospital stay was similar but there was a trend for a reduction in overall hospital mortality in the CPAP group (0.10>P>0.05). Plasma BNP concentrations rose progressively (P<0.001) before falling below admission concentrations at 24 h. Plasma neurohumoral concentrations were unaffected by CPAP treatment but were elevated in patients who died or had acute myocardial infarction. CONCLUSION: CPAP produces a more rapid clinical and symptomatic improvement in patients with acute pulmonary oedema, particularly within the first hour. CPAP is a useful adjunctive treatment in the early management of acute heart failure.

Effect of continuous positive airway pressure on sleep architecture in the sleep apnea-hypopnea syndrome: a randomized controlled trial.

There is randomized controlled evidence that patients with sleep apnea-hypopnea syndrome (SAHS) treated with continuous positive airway pressure (CPAP) have improved daytime function and quality of life. "Before-and-after" data indicate that CPAP improves sleep quality, but there is no randomized controlled evidence of this. We tested the hypothesis that CPAP improved sleep quality in patients with SAHS. We also sought correlations between polysomnographic (PSG) indices and benefit from use of CPAP. Twenty-two patients with SAHS (median, [interquartile range] apnea-hypopnea index, 40 [25-65] events/h) spent 1 mo receiving CPAP and 1 mo receiving placebo capsules, in random order, and home sleep studies were performed at the end of each month. CPAP resulted in a lower arousal index, less Stage 1, and more Stage 3+4 sleep, but there was no increase in Stage REM (rapid eye movement) sleep. Improvement in Epworth score after 6-12 mo of treatment correlated significantly with PSG indices on CPAP: sleep efficiency index (r = 0.78, p < 0.001), Stage REM (r = 0.55, p = 0.001), Stage 3+4 (r = 0.5, p = 0.02), and arousal index (r = -0.43, p = 0.05). This study provides randomized controlled trial evidence that patients with SAHS sleep better when receiving CPAP. Patients with good sleep quality on CPAP at 1 mo are likely to gain later benefit in subjective daytime sleepiness.