Sleep bruxism events: an epiphenomenon of severe obstructive sleep apnea?

OBJECTIVES: This study investigated the temporal relationships between apnea-hypopnea (AH) and sleep bruxism (SB) events and correlated SB to various respiratory/sleep indexes in adult patients with concomitant obstructive sleep apnea (OSA) and SB. MATERIALS AND METHODS: Nocturnal PSG data of 147 consecutive OSA patients were examined for comorbid SB. Among the 49 subjects with coexisting OSA and SB, 26 were randomly selected for in-depth appraisal of temporal patterns which were classified as T1 (unrelated activities), T2 (AH events occur before SB events), T3 (SB events occur before AH events), and T4 (AH and SB events occur simultaneously). Data were analyzed using Mann-Whitney U tests and Spearman's correlation (α = 0.05). RESULTS: The majority (84.5%) of AH events were unrelated to SB events. Of the 15.5% of related activities, T2 and T3 patterns occurred in 14.1% and 1.4%, respectively. SB events/index, the percentage of unrelated/related AH-SB events, and T2-T3 episodes were not associated with gender, age, body mass (BMI), and apnea-hypopnea (AHI) index. SB events were related to total sleep time (rs = 0.44), but no significant associations were discerned between SB and AH index. CONCLUSIONS: As most AH events were unrelated to SB events, OSA and SB are probably epiphenomena in adult patients with concomitant conditions. Where AH-SB events were related, the T2 temporal pattern, where SB events were subsequent to AH events, featured predominantly alluding to a specific form of secondary SB triggered by sleep micro-arousals. CLINICAL RELEVANCE: AH and SB events are probably epiphenomena in adult patients with coexisting OSA and SB. Even so, OSA patients should be routinely screened for SB and vice versa considering their frequent comorbidity.

Lived experience of patients with sleep apnea: a systematic synthesis of qualitative evidence.

BACKGROUND: Sleep apnea (SA) is a prevalent chronic disease with significant morbidity that negatively impacts a patient's perception of health and quality of life (QoL). OBJECTIVE: This review synthesized qualitative evidence on the experiences of patients living with SA to understand the disease's impacts on QoL. METHODS: We performed a systematic review of qualitative studies and searched eight electronic databases from inception dates to 22 September 2020. We analyzed the data using Sandelowski's proposed method of meta-synthesis, and applied Critical Appraisal Skills Program (CASP) and GRADE-Confidence in the Evidence from Reviews of Qualitative research (GRADE-CERQual) criteria to appraise the studies' qualities, and synthesized findings, respectively. RESULTS: Fourteen qualitative studies met the selection criteria. Four themes and 16 subthemes emerged: (1) sleep-related manifestations (n = 14) with four subthemes (sleep disruptors; sleepiness & napping; fatigue & low energy level; decreased cognition), (2) reduced psychological well-being and functioning (n = 14) with seven subthemes (anxiety & feeling vulnerable; hostility; sadness, sense of hopelessness & depression; embarrassment, shame & diminished self-concept; guilt & self-blame; maladaptive coping; self-stigma, (3) impaired physical and role functioning (n = 13) with three subthemes (reduced activities & routine disruption; reduced sexual activities & desire; reduced job performance & participation), (4) impaired social and relational functioning (n = 13) with two subthemes (strained interpersonal relationships; social isolation & loneliness). CONCLUSIONS: SA patients experienced sleep-disrupting symptoms and daytime sleepiness/fatigue which adversely impacted physical, psycho-cognitive, and social aspects of their lives in complex interactive ways. This understanding can help facilitate patient-centric care and develop comprehensive patient-reported measures to effect good health outcomes.

Obstructive sleep apnea during rapid eye movement sleep in patients after percutaneous coronary intervention: a multicenter study.

PURPOSE: Obstructive sleep apnea (OSA) during the rapid eye movement (REM) stage of the sleep cycle is associated with intense hypoxemia and cardiovascular instability. We characterized OSA during REM sleep in patients after percutaneous coronary intervention. METHODS: In this multicenter study, 204 patients who had undergone percutaneous coronary intervention in the prior 6 to 36 months were recruited for in-laboratory polysomnography. The primary measure was respiratory events during REM sleep. The patients were divided into 2 groups: (1) OSA during REM sleep (≥ 15 events/h) and (2) absence of OSA during REM sleep (< 15 events/h). RESULTS: Based on the overall apnea-hypopnea index ≥ 15, 148 patients (74.0%) had OSA. After excluding patients with failed polysomnography or REM sleep < 30 min, 163 patients formed the cohort for this analysis. OSA during REM sleep was diagnosed in 132 patients (81%). Compared with the patients without OSA during REM sleep, those with OSA during REM sleep had a higher body mass index (p = 0.003) and systolic blood pressure (p = 0.041), and a higher prevalence of diabetes mellitus (p = 0.029). Logistic regression analysis, including age, sex, diabetes mellitus, indication for percutaneous coronary intervention, and indication for multi-vessel percutaneous coronary intervention, showed that diabetes mellitus was the only independent predictor of OSA during REM sleep (odds ratio 2.83; 95% CI, 1.17 to 6.83; p = 0.021). CONCLUSION: In patients treated with percutaneous coronary intervention, there was a high prevalence of OSA during REM sleep. Diabetes mellitus was an independent predictor of OSA during REM sleep.

Screening and treatment of obstructive sleep apnea in acute coronary syndrome. A randomized clinical trial.

BACKGROUND: We evaluated the effects of sleep-study guided multidisciplinary therapy (SGMT) of obstructive sleep apnoea (OSA) in patients presenting with acute coronary syndrome. METHODS: Eligible patients were randomized into (1) SGMT, comprised a sleep study during the index admission and continuous positive airway pressure and behavioral therapy for those with at least mild OSA or (2) standard therapy. The primary end point was the change in the plasma N-terminal pro-brain natriuretic peptide (NT-proBNP) level from baseline to the 7-month follow-up. RESULTS: A total of 159 patients completed the trial. Of the 70 patients randomized to SGMT, 21 (30%), 15 (22%) and 27 (39%) were diagnosed with mild, moderate and severe OSA, respectively. Continuous positive airway pressure and a positional pillow were prescribed to 57 (91%) and 6 (9%) patients with OSA. Although plasma NT-proBNP levels were lower after 7 months compared to the baseline, the levels did not differ significantly between the SGMT and standard therapy groups at baseline (579 ±â€¯1117 vs. 611 ±â€¯899 pg/dL, p = .851) or at 7 months (90 ±â€¯167 vs. 93 ±â€¯174 pg/dL, p = .996). The changes in NT-proBNP levels from baseline to 7 months were similar with SGMT and standard therapy (-489 vs. -518 pg/dL, p = .726). Similar findings were observed for the plasma ST2 and hs-CRP levels. CONCLUSIONS: OSA screening and multifaceted treatment during the sub-acute phase of acute coronary syndrome did not further reduce the levels of cardiovascular biomarkers when compared with standard therapy. CLINICAL TRIAL REGISTRATION: clinicaltrial.gov NCT02599298.

Prevalence of and factors associated with poor sleep quality and short sleep in a working population in Singapore.

OBJECTIVES: We aimed to examine the prevalence of poor sleep quality and short sleep and their associated factors in a working population in Singapore. DESIGN: This is a cross-sectional analysis. SETTING: Four companies in Singapore were included in this study. PARTICIPANTS: Participants included 464 full-time employees (aged ≥21 years). MEASUREMENTS: Self-reported sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI). Self-administered questionnaires were used to collect data on sociodemographic characteristics, health behaviours, medical history, chronotype, psychosocial factors, health-related quality of life (HRQoL) and occupational factors. Clinical measurements were performed using standard tools and protocols. Multivariate logistic regression was used to examine the factors associated with poor sleep quality (PSQI global score >5) and short sleep (<7 hours/night). RESULTS: The mean age was 39.0 (SD: 11.4) years, and 79.5% were men. The prevalence of poor sleep quality was 42.5%, and 66.2% were short sleepers. Nearly three-fourths (71.3%) had at least one of these two conditions. Age, Malay ethnicity (vs. Chinese), chronic conditions, poorer mental health, stress at home or work and shift work were positively associated, and mental component summary of the HRQoL scale and work years in the current company were negatively associated with poor sleep quality. Age, Malay and Indian ethnicities (vs. Chinese), longer dinner-to-bed time, snacking between dinner and bed time, and poorer mental health were positively associated with short sleep. CONCLUSIONS: Poor sleep quality and short sleep were highly common in this working population in Singapore. Workplace policies should include education and intervention programmes to promote better sleep hygiene.

Examining the Factor Structure of the Pittsburgh Sleep Quality Index in a Multi-Ethnic Working Population in Singapore.

The Pittsburgh Sleep Quality Index (PSQI) is a widely used measure for assessing sleep impairment. Although it was developed as a unidimensional instrument, there is much debate that it contains multidimensional latent constructs. This study aims to investigate the dimensionality of the underlying factor structure of the PSQI in a multi-ethnic working population in Singapore. The PSQI was administered on three occasions (baseline, 3 months and 12 months) to full-time employees participating in a workplace cohort study. Exploratory factor analysis (EFA) investigated the latent factor structure of the scale at each timepoint. Confirmatory factor analysis (CFA) evaluated the model identified by EFA, and additionally evaluated it against a single factor and a three-factor model. The EFA identified a two-factor model with similar internal consistency and goodness-of-fit across each timepoint. In the CFA, the two- and three-factor models were both superior to the unidimensional model. The two- and three-factor models of the PSQI were reliable, consistent and provided similar goodness-of-fit over time, and both models were superior to the unidimensional measure. We recommend using the two-factor model to assess sleep characteristics in working populations in Singapore, given that it performs as well as the three-factor model and is simpler compared to the latter.

A Multifactorial Approach to Sleep and Its Association with Health-Related Quality of Life in a Multiethnic Asian Working Population: A Cross-Sectional Analysis.

This study aims to explore if objectively and subjectively measured sleep parameters are associated with physical and mental health-related quality of life in a multiethnic working population in Singapore. We performed a cross-sectional analysis with data from 329 full-time employees enrolled in a workplace cohort study in Singapore. The Short-Form 36v2 (SF-36v2) survey was used to assess health-related quality of life, in terms of physical and mental health. Subjective and objective sleep parameters were measured using the Pittsburgh Sleep Quality Index and wrist actigraphy, respectively. Generalized linear modeling was performed to examine the association between sleep parameters and health-related quality of life. After adjusting for confounders, subjectively measured sleep disturbances were associated with a lower physical health-related quality of life, whereas higher, objectively measured sleep efficiency was associated with greater physical health-related quality of life. Subjectively measured daytime dysfunction was associated with impaired mental health-related quality of life. Using both objective and subjective measurements of sleep, the current study suggests that there is an association between sleep and health-related quality of life. Workplace health-promotion planners in Singapore should consider programmes that educate workers on better sleep hygiene practices in an effort to improve sleep and health-related quality of life.

The association between nutritional adequacy and 28-day mortality in the critically ill is not modified by their baseline nutritional status and disease severity.

BACKGROUND: During the initial phase of critical illness, the association between the dose of nutrition support and mortality risk may vary among patients in the intensive care unit (ICU) because the prevalence of malnutrition varies widely (28 to 78%), and not all ICU patients are severely ill. Therefore, we hypothesized that a prognostic model that integrates nutritional status and disease severity could accurately predict mortality risk and classify critically ill patients into low- and high-risk groups. Additionally, in critically ill patients placed on exclusive nutritional support (ENS), we hypothesized that their risk categories could modify the association between dose of nutrition support and mortality risk. METHODS: A prognostic model that predicts 28-day mortality was built from a prospective cohort study of 440 patients. The association between dose of nutrition support and mortality risk was evaluated in a subgroup of 252 mechanically ventilated patients via logistic regressions, stratified by low- and high-risk groups, and days of exclusive nutritional support (ENS) [short-term (≤ 6 days) vs. longer-term (≥ 7 days)]. Only the first 6 days of ENS was evaluated for a fair comparison. RESULTS: The prognostic model demonstrated good discrimination [AUC 0.78 (95% CI 0.73-0.82), and a bias-corrected calibration curve suggested fair accuracy. In high-risk patients with short-term ENS (≤ 6 days), each 10% increase in goal energy and protein intake was associated with an increased adjusted odds (95% CI) of 28-day mortality [1.60 (1.19-2.15) and 1.47 (1.12-1.86), respectively]. In contrast, each 10% increase in goal protein intake during the first 6 days of ENS in high-risk patients with longer-term ENS (≥ 7 days) was associated with a lower adjusted odds of 28-day mortality [0.75 (0.57-0.99)]. Despite the opposing associations, the mean predicted mortality risks and prevalence of malnutrition between short- and longer-term ENS patients were similar. CONCLUSIONS: Combining baseline nutritional status and disease severity in a prognostic model could accurately predict 28-day mortality. However, the association between the dose of nutrition support during the first 6 days of ENS and 28-day mortality was independent of baseline disease severity and nutritional status.

Prevalence of Sleep Bruxism and Its Association with Obstructive Sleep Apnea in Adult Patients: A Retrospective Polysomnographic Investigation.

AIMS: To determine the prevalence of sleep bruxism (SB) in adult obstructive sleep apnea (OSA) patients, to assess the association between SB and OSA in terms of sleep macrostructure and respiratory parameters, and to determine possible OSA risk factors for SB. METHODS: Type I polysomnographic data of 147 adult OSA patients (mean age 44.6 ± 12.8 years) were evaluated for SB. SB episodes were scored when masseter rhythmic masticatory muscle activity (RMMA) was twice the background electromyography amplitude, and SB was established when patients had more than four SB episodes per hour of sleep. Demographic characteristics, sleep macrostructure, and respiratory parameters, including respiratory-related arousal index (RAI), spontaneous arousal index (SAI), oxygen desaturation index (ODI), and Apnea-Hypopnea Index (AHI), were analyzed for differences between patients with and without SB using independent samples t test and Mann-Whitney U test. Multivariate logistic regression analysis was performed to determine the odds of OSA risk factors for SB. RESULTS: Approximately one-third (33.3%) of the adult OSA patients had concomitant SB. Most of the RMMA observed in OSA-SB patients was phasic in nature. OSA patients with SB demonstrated significantly greater RAI (P = .001) and ODI (P = .005). RAI (odds ratio = 1.05, 95% confidence interval = 1.00 to 1.10) and SAI (odds ratio = 0.89, 95% confidence interval = 0.80 to 0.96) demonstrated marginal effects on the odds of experiencing SB. CONCLUSION: About one-third of adult OSA patients had SB, and these patients demonstrated significantly more respiratory-related arousals and oxygen desaturations. These findings suggest that a phenotypic subtype of OSA patients with predominantly phasic SB exists and allude to a possible protective role of RMMA in respiratory-related arousals.

When timing and dose of nutrition support were examined, the modified Nutrition Risk in Critically Ill (mNUTRIC) score did not differentiate high-risk patients who would derive the most benefit from nutrition support: a prospective cohort study.

BACKGROUND: The timing and dose of exclusive nutrition support (ENS) have not been investigated in previous studies aimed at validating the modified Nutrition Risk in Critically Ill (mNUTRIC) score. We therefore evaluated the mNUTRIC score by determining the association between dose of nutrition support and 28-day mortality in high-risk patients who received short- and longer-term ENS (≤ 6 days vs. ≥ 7 days). METHODS: A prospective cohort study included data from 252 adult patients with > 48 h of mechanical ventilation in a tertiary care institution in Singapore. The dose of nutrition support (amount received ÷ goal: expressed in percentage) was calculated for a maximum of 14 days. Associations between the dose of energy (and protein) intake and 28-day mortality were evaluated with multivariable Cox regressions. Since patients have different durations of ENS, only the first 6 days of ENS in patients with short- and longer-term ENS were assessed in the Cox regressions to ensure a valid comparison of the associations between energy (and protein) intake and 28-day mortality. RESULTS: In high-risk patients with short-term ENS (n = 106), each 10% increase in goal energy intake was associated with an increased hazard of 28-day mortality [adj-HR 1.37 (95% CI 1.17, 1.61)], and this was also observed for protein intake [adj-HR 1.31 (95% CI 1.10, 1.56)]. In contrast, each 10% increase in goal protein intake in high-risk patients with longer-term ENS (n = 146) was associated with a lower hazard of 28-day mortality [adj-HR 0.78 (95% CI 0.66, 0.93)]. The mean mNUTRIC scores in these two groups of patients were similar. CONCLUSION: When timing and dose of nutrition support were examined, the mNUTRIC did not differentiate high-risk patients who would derive the most benefit from nutrition support.

Sleep study-guided multidisciplinary therapy (SGMT) for patients with acute coronary syndrome: Trial rationale and design.

Obstructive sleep apnea (OSA) is an emerging risk marker for acute coronary syndrome (ACS). This randomized trial aims to determine the effects of sleep study-guided multidisciplinary therapy (SGMT) comprising overnight sleep study, continuous positive airway pressure, and behavioral therapy for OSA during the subacute phase of ACS. We hypothesize that SGMT will reduce (1) the plasma levels of N-terminal pro brain natriuretic peptide and suppression of tumorigenicity 2; (2) the estimated 10-year risk of cardiovascular mortality as measured by the European Systematic Coronary Risk Evaluation (SCORE) algorithm; and (3) the cardiovascular event rate during a 3-year follow-up, compared with standard therapy. In the SGMT trial, 180 patients presenting with ACS will be randomly assigned to SGMT (n = 90) and standard therapy (n = 90) groups. Both groups will receive guideline-mandated treatment for ACS. Those assigned to SGMT will additionally undergo a sleep study and, if OSA is diagnosed, attend a multidisciplinary OSA clinic where they will receive personalized treatment including continuous positive airway pressure and behavioral/lifestyle counseling. The primary endpoint is the plasma N-terminal pro brain natriuretic peptide concentration at 7-month follow-up. This report presents the baseline characteristics of 117 patients (SGMT group: n =54; standard therapy group: n =63) who had been enrolled into the study as of August 31, 2017. The results of this trial will help us to understand whether active OSA diagnosis and treatment will improve the physiologic and clinical cardiovascular outcomes of this group of patients.

Combining 2 Commonly Adopted Nutrition Instruments in the Critical Care Setting Is Superior to Administering Either One Alone.

BACKGROUND: This study aimed to determine the agreement between the modified Nutrition Risk in Critically ill Score (mNUTRIC) and the Subjective Global Assessment (SGA) and compare their ability in discriminating and quantifying mortality risk independently and in combination. METHODS: Between August 2015 and October 2016, all patients in a Singaporean hospital received the SGA within 48 hours of intensive care unit admission. Nutrition status was dichotomized into presence or absence of malnutrition. The mNUTRIC of patients was retrospectively calculated at the end of the study, and high mNUTRIC was defined as scores ≥5. RESULTS: There were 439 patients and 67.9% had high mNUTRIC, whereas only 28% were malnourished. Hospital mortality was 29.6%, and none was lost to follow-up. Although both tools had poor agreement (κ statistics: 0.13, P < .001), they had similar discriminative value for hospital mortality (C-statistics [95% confidence interval (CI)], 0.66 [0.62-0.70] for high mNUTRIC and 0.61 [0.56-0.66] for malnutrition, P = .12). However, a high mNUTRIC was associated with higher adjusted odds for hospital mortality compared with malnutrition (adjusted odds ratio [95% CI], 5.32 [2.15-13.17], P < .001, and 4.27 [1.03-17.71], P = .046, respectively). Combination of both tools showed malnutrition and high mNUTRIC were associated with the highest adjusted odds for hospital mortality (14.43 [5.38-38.78], P < .001). CONCLUSION: The mNUTRIC and SGA had poor agreement. Although they individually provided a fair discriminative value for hospital mortality, the combination of these approaches is a better discriminator to quantify mortality risk.

Association Between Malnutrition and Clinical Outcomes in the Intensive Care Unit: A Systematic Review [Formula: see text].

Malnutrition is associated with poor clinical outcomes among hospitalized patients. However, studies linking malnutrition with poor clinical outcomes in the intensive care unit (ICU) often have conflicting findings due in part to the inappropriate diagnosis of malnutrition. We primarily aimed to determine whether malnutrition diagnosed by validated nutrition assessment tools such as the Subjective Global Assessment (SGA) or Mini Nutritional Assessment (MNA) is independently associated with poorer clinical outcomes in the ICU and if the use of nutrition screening tools demonstrate a similar association. PubMed, CINAHL, Scopus, and Cochrane Library were systematically searched for eligible studies. Search terms included were synonyms of malnutrition, nutritional status, screening, assessment, and intensive care unit. Eligible studies were case-control or cohort studies that recruited adults in the ICU; conducted the SGA, MNA, or used nutrition screening tools before or within 48 hours of ICU admission; and reported the prevalence of malnutrition and relevant clinical outcomes including mortality, length of stay (LOS), and incidence of infection (IOI). Twenty of 1168 studies were eligible. The prevalence of malnutrition ranged from 38% to 78%. Malnutrition diagnosed by nutrition assessments was independently associated with increased ICU LOS, ICU readmission, IOI, and the risk of hospital mortality. The SGA clearly had better predictive validity than the MNA. The association between malnutrition risk determined by nutrition screening was less consistent. Malnutrition is independently associated with poorer clinical outcomes in the ICU. Compared with nutrition assessment tools, the predictive validity of nutrition screening tools were less consistent.

Association between Malnutrition and 28-Day Mortality and Intensive Care Length-of-Stay in the Critically ill: A Prospective Cohort Study.

There is limited evidence for the association between malnutrition and mortality as well as Intensive Care Unit length-of-stay (ICU-LOS) in critically ill patients. We aimed to examine the aforementioned associations by conducting a prospective cohort study in an ICU of a Singapore tertiary hospital. Between August 2015 and October 2016, all adult patients with ≥ 24 h of ICU-LOS were included. The 7-point Subjective Global Assessment (7-point SGA) was used to determine patients' nutritional status within 48 h of ICU admission. Multivariable regressions were conducted in two ways: (1) presence versus absence of malnutrition, and (2) dose-dependent association for each 1-point decrease in the 7-point SGA. There were 439 patients of which 28.0% were malnourished, and the 28-day mortality rate was 28.0%. Malnutrition was associated with an increased risk of 28-day mortality (adjusted Relative Risk 1.33 (95% Confidence Interval: 1.05-1.69)), and this risk increased with a greater degree of malnutrition (adjusted Relative Risk 1.08 (95% Confidence Interval: 1.00-1.16) for each 1-point decrease in the 7-point SGA). No significant association was found between malnutrition and ICU-LOS. The results of this study indicated a clear association between malnutrition and higher 28-day mortality in critically ill patients. The association between malnutrition and ICU-LOS could not be replicated and hence requires further evaluation.

Sleep bruxism: Current knowledge and contemporary management.

Bruxism is defined as the repetitive jaw muscle activity characterized by the clenching or grinding of teeth. It can be categorized into awake and sleep bruxism (SB). Frequent SB occurs in about 13% of adults. The exact etiology of SB is still unknown and probably multifactorial in nature. Current literature suggests that SB is regulated centrally (pathophysiological and psychosocial factors) and not peripherally (morphological factors). Cited consequences of SB include temporomandibular disorders, headaches, tooth wear/fracture, implant, and other restoration failure. Chairside recognition of SB involves the use of subjective reports, clinical examinations, and trial oral splints. Definitive diagnosis of SB can only be achieved using electrophysiological tools. Pharmacological, psychological, and dental strategies had been employed to manage SB. There is at present, no effective treatment that "cures" or "stops" SB permanently. Management is usually directed toward tooth/restoration protection, reduction of bruxism activity, and pain relief.

Sleep-disordered Breathing in Cardiac Rehabilitation: Prevalence, Predictors, and Influence on the Six-Minute Walk Test.

BACKGROUND: Identification of non-traditional risk factors is an important component of cardiac rehabilitation (CR). However, the prevalence and predictors of sleep-disordered breathing (SDB) and its influence on exercise performance in patients attending CR remain poorly described. METHODS: Patients enrolled in a national CR centre were eligible for a comprehensive SDB screening program. Screening questionnaires for SDB, overnight sleep study, and the 6-minute walk test (6MWT) were conducted. RESULTS: We recruited 332 patients (mean age 62±10 years, 62.4% male) attending CR for primary (29.2%) or secondary (70.8%) prevention, of which 209 successfully completed the overnight sleep study. Sleep-disordered breathing group patients (n=68, 32.5%) were older and had a higher body mass index (BMI) and neck and waist circumferences than the non-SDB group patients. After adjusting for neck and waist circumference, age (OR=1.06; 95% CI 1.02-1.10; p=0.001) and BMI (OR=1.19; 95% CI 1.10-1.30; p<0.001) remained independent predictors of SDB. A high risk of SDB based on the Berlin Questionnaire (43.4% versus 35.5%, p=0.277) or STOP-BANG questionnaire (63.2% versus 53.2%, p=0.170) and excessive daytime sleepiness (Epworth Sleepiness Scale >10, 23.9% versus 17.7%, p=0.297) were similar between the groups. The 6MWT scores were significantly lower in the SDB than non-SDB group (mean difference -32 m; 95% CI -57-7; p=0.013). The relationship was no longer significant after adjusting for age, sex, and waist circumference. CONCLUSION: Sleep-disordered breathing is prevalent in CR patients and is independently predicted by ageing and obesity. The association between SDB and poorer exercise performance may be explained by age, sex, and waist circumference.

Long-term continuous positive airway pressure therapy normalizes high exhaled nitric oxide levels in obstructive sleep apnea.

STUDY OBJECTIVES: Upper airway inflammation and oxidative stress have been implicated in the pathogenesis of obstructive sleep apnea (OSA) and may be linked to cardiovascular consequences. We prospectively examined fraction of exhaled nitric oxide (FENO), a surrogate marker of upper airway inflammation using a portable nitric oxide analyzer (NIOX MINO). DESIGN: In consecutive adult nonsmokers with suspected OSA, FENO was measured immediately before and after polysomnographic studies, and within 1-3 months following continuous positive airway pressure (CPAP) therapy. MEASUREMENT AND RESULTS: FENO levels were increased in the 75 patients with OSA compared to the 29 controls, both before sleep (13.4 ± 6.5 ppb vs. 6.5 ± 3.5; p < 0.001) and after sleep (19.0 ± 7.7 ppb vs. 6.9 ± 3.7; p < 0.001). Furthermore, in patients with OSA, FENO levels were significantly higher post-sleep than pre-sleep (19.0 ± 7.7 ppb vs. 13.4 ± 6.5; p < 0.001), while there was no significant overnight change in patients without OSA. The rise in FENO correlated with the apnea-hypopnea index (r = 0.65, p < 0.001), nadir oxygen saturation (r = 0.54, p < 0.001), and arousal index (r = 0.52, p < 0.001). Thirty-seven of these patients underwent CPAP titration and treatment. Successful titration was associated with a lower overnight increase in FENO (7.2 ± 3.3 vs. 11.0 ± 4.3, p = 0.02). FENO levels declined after 1-3 months of CPAP therapy (11.7 ± 4.4 ppb, p < 0.001). CONCLUSIONS: FENO levels are elevated in OSA, correlate with severity, and decrease after positive pressure therapy. This study supports the role of upper airway inflammation in OSA pathogenesis and a possible role for FENO in monitoring CPAP therapy.

An impulse radio ultrawideband system for contactless noninvasive respiratory monitoring.

We design a impulse radio ultrawideband radar monitoring system to track the chest wall movement of a human subject during respiration. Multiple sensors are placed at different locations to ensure that the backscattered signal could be detected by at least one sensor no matter which direction the human subject faces. We design a hidden Markov model to infer the subject facing direction and his or her chest movement. We compare the performance of our proposed scheme on 15 human volunteers with the medical gold standard using respiratory inductive plethysmography (RIP) belts, and show that on average, our estimation is over 81% correlated with the measurements of a RIP belt system. Furthermore, in order to automatically differentiate between periods of normal and abnormal breathing patterns, we develop a change point detection algorithm based on perfect simulation techniques to detect changes in the subject's breathing. The feasibility of our proposed system is verified by both the simulation and experiment results.

Effect of a pleural checklist on patient safety in the ultrasound era.

BACKGROUND AND OBJECTIVE: Bedside ultrasound allows direct visualization of pleural collections for thoracentesis and tube thoracostomy. However, there is little information on patient safety improvement methods with this approach. The effect of a checklist on patient safety for bedside ultrasound-guided pleural procedures was evaluated. METHODS: A prospective study of ultrasound-guided pleural procedures from September 2007 to June 2010 was performed. Ultrasound guidance was routine practice for all patients under the institution's care and the freehand method was used. All operators took a half-day training session on basic thoracic ultrasound and were supervised by more experienced operators. A 14-item checklist was introduced in June 2009. It included systematic thoracic scanning and a safety audit. Clinical and safety data are described before (Phase I) and after (Phase II) the introduction of the checklist. RESULTS: There were 121 patients in Phase I (58.7 ± 18.9 years) and 134 patients in Phase II (60.2 ± 19.6 years). Complications occurred for 10 patients (8.3%) in Phase I (six dry taps, three pneumothoraces, one haemothorax) and for 2 patients (1.5%) in Phase II (one significant bleed, one malposition of chest tube) (P = 0.015). There were no procedure-related deaths. The use of the checklist alone was associated with fewer procedure-related complications. This was independent of thoracostomy rate, pleural effusion size and pleural fluid ultrasound appearance. CONCLUSIONS: A pleural checklist with systematic scanning and close supervision may further enhance safety of ultrasound-guided procedures. This may also help promote safety while trainees are learning to perform these procedures.