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Objectives: Although continuous positive airway pressure (CPAP) effectively prevents sleep apnea and reduces blood pressure, many patients do not use CPAP every night. This trial investigates cardiovascular effects after sleeping five nights without CPAP.

Methods: We randomized 100 patients (67 men and 33 women with a mean age 64±9 years) using CPAP treatment for moderate-to-severe sleep apnea to either withdraw treatment for five nights (n=50) or to continue with CPAP (n=50). The primary outcomes were arterial stiffness and 24h blood pressure.

Results: The 24h SBP increased by a mean of 2.8mmHg [95% confidence interval (CI) 0.2-5.4mmHg] (P=0.035) and DBP increased by a mean of 1.7mmHg (95% CI 0.1-3.3mmHg) (P=0.032) in the group without CPAP compared to the CPAP group. There was a significant effect on blood pressure in women but not in men. In women, SBP increased by 5.1mmHg (95% CI 1.0-9.5mmHg) (P=0.017) and DBP by 2.9mmHg (95% CI 0.4-5.6mmHg) (P=0.029). Arterial stiffness remained unaffected. Secondary outcomes that worsened in patients without CPAP included apnea-hypopnea index, oxygen desaturation index, hemoglobin levels, and daytime sleepiness.

Conclusion: Blood pressure is affected after five nights of CPAP interruption, along with a rapid return of sleep apneas, nocturnal hypoxic events, daytime sleepiness and increased hemoglobin levels, but arterial stiffness was not affected. Blood pressure was affected in women only, suggesting a sex-related CPAP effect on blood pressure.

Excessive daytime sleepiness (EDS) is a common complaint in the general population and is associated with cardiovascular disease and increased mortality. We aimed to investigate whether sleep duration is related to excessive daytime sleepiness in the general population, both in itself and in combination with other factors. We performed a cross-sectional analysis in the population-based Swedish CArdioPulmonary bioImage Study (SCAPIS) cohort (n = 27,976; 14,436 females; aged 50–64 years) to assess how sleep-related factors along with anthropometric, lifestyle, socioeconomic factors as well as somatic disease and psychological distress, were related with EDS assessed by the Epworth sleepiness scale (ESS). Analyses were performed using logistic regression modelling with EDS defined by an ESS score of ≥11 as the main outcome. Both short and long sleep duration were related to EDS with increasing ORs for decreasing sleep duration (7 h vs. reference (8 h): OR 1.2, 95% CI 1.02–1.3 to ≤4 h: 1.9; 1.4–2.5). In addition to sleep-related factors such as insomnia (1.3; 1.2–1.4), poor sleep quality (1.2; 1.04–1.4), snoring (1.5; 1.4–1.6), and nocturnal gastro-oesophageal reflux (1.5; 1.21–1.8), psychological distress showed a strong association with EDS. This included sadness/depression (1.2; 1.1–1.3), stress (some stress: 1.4; 1.1–1.7 to constant stress over 5 years: 1.7; 1.3–2.2), and self-rated "control in life" (lowest quartile: 1.7; 1.6–2.0). Daytime sleepiness is multifactorial and associated with both sleep duration and sleep quality. Strong associations were also established with factors related to psychological distress. Further research may investigate interventions targeting both sleep and psychological health to reduce daytime sleepiness at the societal level.

Obstructive sleep apnoea (OSA) and its associations with lung function.

BACKGROUND: OSA is highly prevalent and characterised by abnormal respiration during sleep. This large, population-based study aimed to investigate the associations between OSA and lung function in subjects aged 50-64 years.

METHOD: The population-based Swedish CArdioPulmonary bioimage Study includes information on anthropometry, comorbidities and spirometry. The current analysis included data from three centres (Gothenburg, Umeå and Uppsala) on whole-night respiratory polygraphy as a meta-analysis examining the overall effect size of lung function on sleep apnoea severity, expressed as ß-coefficient after stratifying for sex and adjusting for age, waist circumference and smoking status.

RESULTS: Data from 9016 participants (54% women, age 58±4 years, body mass index 27±4 kg/m2 ) with sleep recordings of good quality were included in the final analysis. Forced expiratory volume during 1 s (FEV 1 ) (ß=-0.10 (95% CI -0.16 to -0.03)), forced vital capacity (FVC) (-0.15 (-0.21 to -0.10)) and diffusion capacity for carbon monoxide (DLCO ) (-0.08 (-0.10 to -0.05)) were all negatively associated with the oxygen desaturation index (ODI) and also with per cent of registration with nocturnal oxygen saturation <90% FVC (-0.44 (-0.87 to -0.01)), FEV 1 (-0.86 (-1.36 to -0.36)) and DL CO (-0.47 (-0.60 to -0.35)). Additionally, a positive association was observed between FEV 1 (0.13 (0.05 to 0.22)) and DL CO (0.07 (0.04 to 0.09)) with the mean nocturnal saturation. There was a negative association between DL CO and apnoea-hypopnoea index, AHI, (ß=-0.04 (95% CI-0.06 to -0.03)), while no associations were found between FEV 1 or FVC and AHI.

CONCLUSION: In OSA, lower lung function is more distinctly associated with the nocturnal hypoxic burden than AHI. Potential lung function impairment should be investigated in OSA patients with a high ODI relative to AHI.

Background: Without evidence, positive expiratory pressure therapy is a part of rehabilitation worldwide to prevent postoperative hypoxia. Reading aloud could be used as an alternative therapy as lung volumes increases while speaking. We aimed to investigate whether reading aloud is superior to positive expiratory pressure therapy for improving oxygen saturation after abdominal surgery.

Material and Methods: This crossover randomized controlled trial compared reading a text aloud with positive expiratory pressure therapy in patients on postoperative day 1 or 2 after upper gastrointestinal, colorectal, urological, or gynecological abdominal surgery at Umeå University Hospital, Sweden. The primary outcome was the change in peripheral oxygen saturation compared with baseline at 7 min after the intervention. The secondary outcome was transcutaneous carbon dioxide partial pressure change.

Results: This study included 50 patients of which 48 patients were analyzed. Peripheral oxygen saturation rapidly decreased to minimum values below baseline immediately after both interventions and then increased to values above baseline after reading aloud (1%, 95% confidence interval 0.2% to 1%, P = 0.004), but not after positive expiratory pressure therapy (−0.2%, 95% confidence interval −1% to 0.4%, P = 0.436). The difference in oxygen saturation was 1% (95% confidence interval 0.1% to 2%, P = 0.039) at 7 min after termination of the interventions. The interventions reduced transcutaneous carbon dioxide partial pressure by similar amounts.

Conclusions: This trial adds to the evidence against the use of positive expiratory pressure therapy after abdominal surgery. It is even slightly better to read aloud.

Background/Objectives: Obesity is the main risk factor for obstructive sleep apnoea, commonly occurring in females who are overweight after menopause. We aimed to study the effect of a palaeolithic diet on sleep apnoea in females with overweight after menopause from the population.

Methods: Seventy healthy, non-smoking females with a mean age of 60 years and a mean BMI of 33 kg/m2 were randomised to a palaeolithic diet or to a control low-fat diet according to Nordic Nutritional Recommendations, for 2 years. The apnoea-hypopnoea index was measured and daytime sleepiness was estimated during the intervention.

Results: The mean apnoea-hypopnoea index at baseline was 11.6 (95% CI 8.6–14.5). The mean weight loss was 7.2 kg (95% CI 5.3–9.2 kg) in the palaeolithic diet group and 3.9 kg in the control group (95% CI 1.9–5.9 kg); p < 0.021 for the group difference. The reduction in weight corresponded to a reduction in the apnoea-hypopnoea index in the palaeolithic diet group (r = 0.38, p = 0.034) but not in the control group (r = 0.08, p = 0.69). The apnoea-hypopnoea index was reduced in the palaeolithic diet group when the weight was reduced by more than 8 kg. Daytime sleepiness according to the Epworth Sleepiness Scale score and the Karolinska Sleepiness Scale score was unaffected by dietary group allocation.

Conclusions: A substantial decrease in body weight of 8 kg was needed to achieve a reduction in sleep apnoea in this small trial of women who are overweight after menopause. The palaeolithic diet was more effective for weight reduction than a control low-fat diet and the reduction in sleep apnoea was related to the degree of weight decrement within this diet group.

Trial registration: Clinicaltrials.gov: NCT00692536.

An increased prevalence of obstructive sleep apnoea (OSA) has been suggested in patients with ankylosing spondylitis (AS) in a few controlled studies. We aimed to study the prevalence of OSA compared to controls and to investigate if disease-related and non-disease-related factors were determinants of OSA in AS patients. One hundred and fifty-five patients with AS were included in the Backbone study, a cross-sectional study that investigates severity and comorbidities in AS. Controls were recruited from the Swedish CArdioPulmonary bioImage Study. To evaluate OSA, the participants were asked to undergo home sleep-monitoring during one night’s sleep. For each AS patient 45–70 years old, four controls were matched for sex, age, weight, and height. OSA was defined as an apnoea-hypopnoea index (AHI) ≥ 5 events/hour. Sixty-three patients with AS were examined with home sleep-monitoring, and 179 controls were matched with 46 patients, 45–70 years. Twenty-two out of 46 (47.8%) patients with AS vs. 91/179 (50.8%) controls had OSA (AHI ≥ 5 events/hour), P = 0.72. No differences in the sleep measurements were noted in AS patients vs. controls. In logistic regression analysis adjusted for age and sex, higher age, higher BMI, and lesser chest expansion were associated with the presence of OSA in the 63 AS patients. In the current study, patients with AS did not have a higher prevalence of OSA compared to matched controls. AS patients with OSA had higher BMI, were older, and had lesser chest expansion because of more severe AS compared to patients without OSA.

Key points:

• Patients with ankylosing spondylitis did not have a higher prevalence of obstructive sleep apnoea versus matched controls.

• Patients with ankylosing spondylitis and obstructive sleep apnoea were older and had higher body mass index versus patients without obstructive sleep apnoea.

• Patients with ankylosing spondylitis and obstructive sleep apnoea had lesser chest expansion versus patients without obstructive sleep apnoea.

Objective: To evaluate the immediate effects of positive expiratory pressure therapy on oxygen saturation and ventilation after abdominal surgery.

Background: Positive expiratory pressure therapy to treat postoperative hypoxia is widespread, despite a lack of evidence of effect.

Methods: This randomized, sham-controlled, crossover trial investigated adults 1–2 days after abdominal surgery at Umeå University Hospital, Sweden. The intervention was positive expiratory pressure of 10–15 cm H2O. The control was a sham device. The investigations were ended with deep-breathing maneuvers. Outcomes were the gradient of changes in peripheral oxygen saturation and transcutaneous carbon-dioxide partial pressure (PtcCO2).

Results: Eighty patients were included and randomized and 76 patients were analyzed. Oxygen saturation increased from a baseline mean of 92% to 95%, P < 0.001, during positive expiratory pressure breathing, while PtcCO2 decreased from a mean of 36 to 33 mm Hg, P < 0.001. This was followed by apnea, oxygen desaturations to a mean of 89%, P < 0.001, and increased PtcCO2 before returning to baseline values. The changes in oxygen saturation and PtcCO2 did not differ from sham breathing or deep-breathing maneuvers.

Conclusions: Positive expiratory pressure breathing after abdominal surgery improves oxygen saturation during the maneuver because of hyperventilation, but it is followed by apnea, hypoventilation, and oxygen desaturation. The effect is not different from the expiration to a sham device or hyperventilation. It is time to stop positive expiratory pressure therapy after abdominal surgery, as there is no evidence of effect in previous trials, apart from the adverse effects reported here.

Proteomic‐based technologies offer new opportunities to identify proteins that might reflect the cardiometabolic stress caused by different aspects of sleep‐disordered breathing. We aimed to investigate whether severe obstructive sleep apnea and severe obstructive sleep apnea during rapid eye movement sleep are associated with changed levels of inflammatory and cardiac disease‐related proteins in a population‐based cohort of women. In the community‐based “Sleep and Health in Women” (SHE) cohort study, 400 women underwent polysomnography, anthropometric measurements and blood sampling. Two proteomic assays (Olink Proseek^® Inflammation panel and Olink Proseek^® Cardiovascular II panel), each measuring 92 proteins, were analysed in a subsample of 253 women. p‐Values were adjusted for multiple testing, with false discovery rate set at 10%. In unadjusted models, 57 proteins were associated with apnea−hypopnea index, 56 proteins with oxygen desaturation index and 64 proteins with rapid eye movement−apnea−hypopnea index. After adjustment for age, body mass index and plate, there were no significant associations between apnea−hypopnea index or oxygen desaturation index and any of the proteins. Severe obstructive sleep apnea during rapid eye movement sleep (rapid eye movement−apnea−hypopnea index ≥ 30) was associated with decreased levels of two anti‐inflammatory proteins; Sirt2 (q‐value .016) and LAP‐TGF‐β₁ (q‐value .016). There was also a negative association between rapid eye movement−apnea−hypopnea index of ≥ 30 and Axin1 (q‐value .095), a protein thought to facilitate TGF‐β‐signalling. We conclude that severe obstructive sleep apnea during rapid eye movement sleep is associated with low levels of Sirt2, LAP‐TGF‐β₁ and Axin1, anti‐inflammatory proteins involved in metabolic regulation and in the atherosclerotic process. For obstructive sleep apnea based on a whole night, the associations with cardiac and inflammatory proteins are weaker, and explained to a large extent by age and body mass index.

BACKGROUND: Obstructive sleep apnea (OSA) is related to postoperative complications and is a common disorder. Most patients with sleep apnea are, however, undiagnosed, and there is a need for simple screening tools. We aimed to investigate whether STOP-Bang and oxygen desaturation index can identify subjects with OSA.

METHODS: In this prospective, observational multicenter trial, 449 adult patients referred to a sleep clinic for evaluation of OSA were investigated with ambulatory polygraphy, including pulse oximetry and the STOP-Bang questionnaire in 4 Swedish centers. The STOP-Bang score is the sum of 8 positive answers to Snoring, Tiredness, Observed apnea, high blood Pressure, Body mass index >35 kg/m2, Age >50 years, Neck circumference >40 cm, and male Gender.

RESULTS: The optimal STOP-Bang cutoff score was 6 for moderate and severe sleep apnea, defined as apnea-hypopnea index (AHI) ≥15, and the sensitivity and specificity for this score were 63% (95% CI, 0.55–0.70) and 69% (95% CI, 0.64–0.75), respectively. A STOP-Bang score of <2 had a probability of 95% (95% CI, 0.92–0.98) to exclude an AHI >15 and a STOP-Bang score of ≥6 had a specificity of 91% (95% CI, 0.87–0.94) for an AHI >15. The items contributing most to the STOP-Bang were the Bang items. There was a positive correlation between AHI versus STOP-Bang and between AHI versus oxygen desaturation index, Spearman ρ 0.50 (95% CI, 0.43–0.58) and 0.96 (95% CI, 0.94–0.97), respectively.

CONCLUSIONS: STOP-Bang and pulse oximetry can be used to screen for sleep apnea. A STOP-Bang score of <2 almost excludes moderate and severe OSA, whereas nearly all the patients with a STOP-Bang score ≥6 have OSA. We suggest the addition of nightly pulse oximetry in patients with a STOP-Bang score of 2–5 when there is a need for screening for sleep apnea (ie, before surgery).

BACKGROUND: Obstructive sleep apnea is associated with high blood pressure. The magnitude of blood pressure effects from sleep apnea treatment is unclear. We aimed to determine the effect of mandibular advancement device therapy on ambulatory nighttime and daytime blood pressure in women and men with daytime sleepiness and snoring or mild to moderate sleep apnea (apnea-hypopnea index, <30).

METHODS AND RESULTS: In this 4-month, double-blind, randomized controlled trial comprising 96 untreated patients, 27 women and 58 men, aged 31 to 70 years, completed the study. The active group received individually made adjustable mandibular advancement devices, and the control group was given individually made sham devices, to be used during sleep. Polysomnographic sleep recordings and ambulatory 24-hour blood pressure measurements were performed at baseline and at follow-up. In women with mandibular advancement devices, the mean nighttime systolic blood pressure was 10.8 mm Hg (95% confidence interval, 4.0-17.7 mm Hg; P=0.004) lower than in the women in the sham group, adjusted for baseline blood pressure, age, body mass index, and the apnea-hypopnea index. The mean nighttime adjusted diastolic blood pressure was 6.6 mm Hg (95% confidence interval, 2.7-10.4 mm Hg; P=0.002) lower in the mandibular advancement device group. In men, there were no significant differences in blood pressure at night or during the daytime between the intervention groups.

CONCLUSIONS: A mandibular advancement device for obstructive sleep apnea reduces nocturnal blood pressure in women.

CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov. Unique identifier: NCT00477009.