Influence of obstructive sleep apnea on serum butyrylcholinesterase activity and ischemia-modified albumin levels

OBJECTIVE:

To investigate the effect of obstructive sleep apnea and continuous positive airway pressure treatment on serum butyrylcholinesterase activity and ischemia-modified albumin levels.

METHODS:

Thirty-two patients with obstructive sleep apnea and 30 age- and sex-matched controls were enrolled and underwent a diagnostic polysomnogram. The serum butyrylcholinesterase activity, ischemia-modified albumin levels, metabolic parameters, and polysomnography scores were detected and evaluated. Nine patients were studied before and after treatment with continuous positive airway pressure.

RESULTS:

The serum ischemia-modified albumin levels were significantly higher and the butyrylcholinesterase activity was significantly lower in patients with obstructive sleep apnea than in the controls (p<0.001). The continuous positive airway pressure treatment decreased the modified albumin levels and elevated the buthrylcholinesterase activity (p = 0.019 and p = 0.023, respectively). The modified albumin levels were positively correlated with the apnea-hypopnea index (r = 0.462, p = 0.008) at baseline. Elevated ischemia-modified albumin levels can be more accurate than butyrylcholinesterase activity at reflecting the presence of obstructive sleep apnea. Receiver operating characteristic curves revealed a significant difference between the areas under the curve 0.916 for ischemia-modified albumin and 0.777 for butyrylcholinesterase (z = 2.154, p = 0.031).

CONCLUSION:

The elevated ischemia-modified albumin level was significantly associated with obstructive sleep apnea and was more sensitive than butyrylcholinesterase activity in reflecting obstructive sleep apnea. The continuous positive airway pressure treatment helped to ameliorate the imbalance.     

Comparison of the effects of continuous positive airway pressure,oral appliance and exercise training in obstructive sleep apnea syndrome

OBJECTIVE:

There are several treatments for obstructive sleep apnea syndrome, such as weight loss, use of an oral appliance and continuous positive airway pressure, that can be used to reduce the signs and symptoms of obstructive sleep apnea syndrome. Few studies have evaluated the effectiveness of a physical training program compared with other treatments. The aim of this study was to assess the effects of physical exercise on subjective and objective sleep parameters, quality of life and mood in obstructive sleep apnea patients and to compare these effects with the effects of continuous positive airway pressure and oral appliance treatments.

METHODS:

Male patients with moderate to severe obstructive sleep apnea and body mass indices less than 30 kg/m2 were randomly assigned to three groups: continuous positive airway pressure (n = 9), oral appliance (n = 9) and physical exercise (n = 7). Polysomnographic recordings, blood samples and daytime sleepiness measurements were obtained prior to and after two months of physical exercise or treatment with continuous positive airway pressure or an oral appliance. Clinicaltrials.gov: NCT01289392

RESULTS:

After treatment with continuous positive airway pressure or an oral appliance, the patients presented with a significant reduction in the apnea-hypopnea index. We did not observe changes in the sleep parameters studied in the physical exercise group. However, this group presented reductions in the following parameters: T leukocytes, very-low-density lipoprotein and triglycerides. Two months of exercise training also had a positive impact on subjective daytime sleepiness.

CONCLUSIONS:

Our results suggest that isolated physical exercise training was able to modify only subjective daytime sleepiness and some blood measures. Continuous positive airway pressure and oral appliances modified the apnea-hypopnea index.     

Supine sleep and positional sleep apnea after acute ischemic stroke and intracerebral hemorrhage

OBJECTIVE:

Obstructive sleep apnea is frequent during the acute phase of stroke, and it is associated with poorer outcomes. A well-established relationship between supine sleep and obstructive sleep apnea severity exists in non-stroke patients. This study investigated the frequency of supine sleep and positional obstructive sleep apnea in patients with ischemic or hemorrhagic stroke.

METHODS:

Patients who suffered their first acute stroke, either ischemic or hemorrhagic, were subjected to a full polysomnography, including the continuous monitoring of sleep positions, during the first night after symptom onset. Obstructive sleep apnea severity was measured using the apnea-hypopnea index, and the NIHSS measured stroke severity.

RESULTS:

We prospectively studied 66 stroke patients. The mean age was 57.6±11.5 years, and the mean body mass index was 26.5±4.9. Obstructive sleep apnea (apnea-hypopnea index ≥5) was present in 78.8% of patients, and the mean apnea-hypopnea index was 29.7±26.6. The majority of subjects (66.7%) spent the entire sleep time in a supine position, and positional obstructive sleep apnea was clearly present in the other 23.1% of cases. A positive correlation was observed between the NIHSS and sleep time in the supine position (r_s = 0.5; p<0.001).

CONCLUSIONS:

Prolonged supine positioning during sleep was highly frequent after stroke, and it was related to stroke severity. Positional sleep apnea was observed in one quarter of stroke patients, which was likely underestimated during the acute phase of stroke. The adequate positioning of patients during sleep during the acute phase of stroke may decrease obstructive respiratory events, regardless of the stroke subtype.     

A negative expiratory pressure test during wakefulness for evaluating the risk of obstructive sleep apnea in patients referred for sleep studies

OBJECTIVE:

Obstructive sleep apnea is characterized by increased upper airway collapsibility during sleep. The present study investigated the use of the negative expiratory pressure test as a method to rule out obstructive sleep apnea.

METHODS:

Flow limitation was evaluated in 155 subjects. All subjects underwent a diurnal negative expiratory pressure test and a nocturnal sleep study. The severity of sleep apnea was determined based on the apnea-hypopnea index. Flow limitation was assessed by computing the exhaled volume at 0.2, 0.5, and 1.0 s (V_0.2, V_0.5, and V_1.0, respectively) during the application of a negative expiratory pressure and expressed as a percentage of the previous exhaled volume. Receiver-operating characteristic curves were constructed to identify the optimal threshold volume at 0.2, 0.5, and 1.0 s for obstructive sleep apnea detection.

RESULTS:

Mean expiratory volumes at 0.2 and 0.5 s were statistically higher (p<0.01) in healthy subjects than in all obstructive sleep apneic groups. Increasing disease severity was associated with lower expiratory volumes. The V_0.2 (%) predictive parameters for the detection of sleep apnea were sensitivity (81.1%), specificity (93.1%), PPV (98.1%), and NPV (52.9%). Sensitivity and NPV were 96.9% and 93.2%, respectively, for moderate-to-severe obstructive sleep apnea, and both were 100% for severe obstructive sleep apnea.

CONCLUSION:

Flow limitation measurement by V_0.2 (%) during wakefulness may be a very reliable method to identify obstructive sleep apnea when the test is positive and could reliably exclude moderate and severe obstructive sleep apnea when the test is negative. The negative expiratory pressure test appears to be a useful screening test for suspected obstructive sleep apnea.     

Effect of Continuous Positive Airway Pressure on Sleep Structure in Heart Failure Patients with Central Sleep Apnea

Study Objectives:

At termination of obstructive apneas, arousal is a protective mechanism that facilitates restoration of upper airway patency and airflow. Treating obstructive sleep apnea (OSA) by continuous positive airway pressure (CPAP) reduces arousal frequency indicating that such arousals are caused by OSA. In heart failure (HF) patients with central sleep apnea (CSA), however, arousals frequently occur several breaths after apnea termination, and there is uncertainty as to whether arousals from sleep are a consequence of CSA. If so, they should diminish in frequency when CSA is attenuated. We therefore sought to determine whether attenuation of CSA by CPAP reduces arousal frequency.

Design:

Randomized controlled clinical trial.

Patients and Setting:

We examined data from 205 HF patients with CSA (apnea-hypopnea index [AHI] ≥ 15, > 50% were central) randomized to CPAP or control who had polysomnograms performed at baseline and 3 months later.

Measurements and Results:

In the control group, there was no change in AHI or frequency of arousals. In the CPAP-treated group, the AHI decreased significantly (from [mean ± SD] 38.9 ± 15.0 to 17.6 ± 16.3, P < 0.001) but neither the frequency of arousals nor sleep structure changed significantly.

Conclusion:

These data suggest that attenuation of CSA by CPAP does not reduce arousal frequency in HF patients. We conclude that arousals were not mainly a consequence of CSA, and may not have been acting as a defense mechanism to terminate apneas in the same way they do in OSA.

Citation:

Ruttanaumpawan P; Logan AG; Floras JS; Bradley TD. Effect of Continuous Positive Airway Pressure on Sleep Structure in Heart Failure Patients with Central Sleep Apnea. SLEEP 2009;32(1):91-98.     

Oxidative stress and quality of life in elderly patients with obstructive sleep apnea syndrome: are there differences after six months of Continuous Positive Airway Pressure treatment?

OBJECTIVES:

This study evaluated the effect of Continuous Positive Airway Pressure treatment on oxidative stress parameters and the quality of life of elderly patients with obstructive sleep apnea syndrome.

METHODS:

In total, 30 obstructive sleep apnea syndrome patients and 27 subjects without obstructive sleep apnea syndrome were included in this study. Both groups underwent quality of life and oxidative stress evaluations at baseline and after six months. Polysomnography was performed in both groups at baseline and a second time in the obstructive sleep apnea syndrome group after six months of Continuous Positive Airway Pressure treatment. All of the variables were compared between the control and obstructive sleep apnea syndrome groups in this prospective case-control study.

RESULTS:

The baseline concentrations of the antioxidant enzyme catalase were higher in the obstructive sleep apnea syndrome group than the control group. After Continuous Positive Airway Pressure treatment, the obstructive sleep apnea syndrome group exhibited a reduction in the level of oxidative stress, as indicated by a decrease in the level of lipid peroxidation measured by the malondialdehyde (MDA) concentration [pre: 2.7 nmol malondialdehyde/mL (95% 1.6-3.7) vs. post: 1.3 nmol MDA/mL (0.7-1.9), p<0.01]. Additionally, improvements were observed in two domains covered by the SF-36 questionnaire: functional capacity [pre: 77.4 (69.2-85.5) vs. post: 83.4 (76.9-89.9), p = 0.002] and pain [pre: 65.4 (52.8-78.1) vs. post: 77.8 (67.2-88.3), p = 0.004].

CONCLUSION:

Our study demonstrated that the use of Continuous Positive Airway Pressure to treat obstructive sleep apnea syndrome in elderly patients reduced oxidative stress and improved the quality of life.     

Practice parameters for the surgical modifications of the upper airway for obstructive sleep apnea in adults

Background:

Practice parameters for the treatment of obstructive sleep apnea syndrome (OSAS) in adults by surgical modification of the upper airway were first published in 1996 by the American Academy of Sleep Medicine (formerly ASDA). The following practice parameters update the previous practice parameters. These recommendations were reviewed and approved by the Board of Directors of the American Academy of Sleep Medicine.

Methods:

A systematic review of the literature was performed, and the GRADE system was used to assess the quality of evidence. The findings from this evaluation are provided in the accompanying review paper, and the subsequent recommendations have been developed from this review. The following procedures have been included: tracheostomy, maxillo-mandibular advancement (MMA), laser assisted uvulopalatoplasty (LAUP), uvulopalatopharyngoplasty (UPPP),radiofrequency ablation (RFA), and palatal implants.

Recommendations:

The presence and severity of obstructive sleep apnea must be determined before initiating surgical therapy (Standard). The patient should be advised about potential surgical success rates and complications, the availability of alternative treatment options such as nasal positive airway pressure and oral appliances, and the levels of effectiveness and success rates of these alternative treatments (Standard). The desired outcomes of treatment include resolution of the clinical signs and symptoms of obstructive sleep apnea and the normalization of sleep quality, the apnea-hypopnea index, and oxyhemoglobin saturation levels (Standard). Tracheostomy has been shown to be an effective single intervention to treat obstructive sleep apnea. This operation should be considered only when other options do not exist, have failed, are refused, or when this operation is deemed necessary by clinical urgency (Option). MMA is indicated for surgical treatment of severe OSA in patients who cannot tolerate or who are unwilling to adhere to positive airway pressure therapy, or in whom oral appliances, which are more often appropriate in mild and moderate OSA patients, have been considered and found ineffective or undesirable (Option). UPPP as a sole procedure, with or without tonsillectomy, does not reliably normalize the AHI when treating moderate to severe obstructive sleep apnea syndrome. Therefore, patients with severe OSA should initially be offered positive airway pressure therapy, while those with moderate OSA should initially be offered either PAP therapy or oral appliances (Option). Use of multi-level or stepwise surgery (MLS), as a combined procedure or as stepwise multiple operations, is acceptable in patients with narrowing of multiple sites in the upper airway, particularly if they have failed UPPP as a sole treatment (Option). LAUP is not routinely recommended as a treatment for obstructive sleep apnea syndrome (Standard). RFA can be considered as a treatment in patients with mild to moderate obstructive sleep apnea who cannot tolerate or who are unwilling to adhere to positive airway pressure therapy, or in whom oral appliances have been considered and found ineffective or undesirable (Option). Palatal implants may be effective in some patients with mild obstructive sleep apnea who cannot tolerate or who are unwilling to adhere to positive airway pressure therapy, or in whom oral appliances have been considered and found ineffective or undesirable (Option). Postoperatively, after an appropriate period of healing, patients should undergo follow-up evaluation including an objective measure of the presence and severity of sleep-disordered breathing and oxygen saturation, as well as clinical assessment for residual symptoms. Additionally, patients should be followed over time to detect the recurrence of disease (Standard).

Conclusions:

While there has been significant progress made in surgical techniques for the treatment of OSA, there is a lack of rigorous data evaluating surgical modifications of the upper airway. Systematic and methodical investigations are needed to improve the quality of evidence, assess additional outcome measures, determine which populations are most likely to benefit from a particular procedure or procedures, and optimize perioperative care.

Citation:

Aurora RN; Casey KR; Kristo D; Auerbach S; Bista SR; Chowdhuri S; Karippot A; Lamm C; Ramar K; Zak R; Morgenthaler TI. Practice parameters for the surgical modifications of the upper airway for obstructive sleep apnea in adults. SLEEP 2010;33(10):1408-1413.     

Lack of reliable clinical predictors to identify obstructive sleep apnea in patients with hypertrophic cardiomyopathy

OBJECTIVE:

Obstructive sleep apnea is common among patients with hypertrophic cardiomyopathy and may contribute to poor cardiovascular outcomes. However, obstructive sleep apnea is largely unrecognized in this population. We sought to identify the clinical predictors of obstructive sleep apnea among patients with hypertrophic cardiomyopathy.

METHODS:

Consecutive patients with hypertrophic cardiomyopathy were recruited from a tertiary University Hospital and were evaluated using validated sleep questionnaires (Berlin and Epworth) and overnight portable monitoring. Ninety patients (males, 51%; age, 46±15 years; body mass index, 26.6±4.9 kg/m²) were included, and obstructive sleep apnea (respiratory disturbance index ≥15 events/h) was present in 37 patients (41%).

RESULTS:

Compared with the patients without obstructive sleep apnea, patients with obstructive sleep apnea were older and had higher body mass index, larger waist circumference, larger neck circumference, and higher prevalence of atrial fibrillation. Excessive daytime sleepiness (Epworth scale) was low and similar in the patients with and without obstructive sleep apnea, respectively. The only predictors of obstructive sleep apnea (using a logistic regression analysis) were age ≥45 years (odds ratio [OR], 4.46; 95% confidence interval [CI 95%], 1.47–13.54; p = 0.008) and the presence of atrial fibrillation [OR, 5.37; CI 95%, 1.43–20.12; p = 0.013].

CONCLUSION:

Consistent clinical predictors of obstructive sleep apnea are lacking for patients with hypertrophic cardiomyopathy, which suggests that objective sleep evaluations should be considered in this population, particularly among elderly patients with atrial fibrillation.     

An overlooked cause of resistant hypertension: upper airway resistance syndrome - preliminary results

OBJECTIVE:

Upper airway resistance syndrome is a sleep-disordered breathing syndrome that is characterized by repetitive arousals resulting in sympathetic overactivity. We aimed to determine whether upper airway resistance syndrome was associated with poorly controlled hypertension.

METHODS:

A total of 40 patients with resistant hypertension were enrolled in the study. All of the patients underwent polysomnographic examinations and 24-hour ambulatory blood pressure monitoring to exclude white coat syndrome and to monitor treatment efficiency. Among 14 upper airway resistance syndrome patients, 2 patients had surgically correctable upper airway pathologies, while 12 patients were given positive airway pressure therapy.

RESULTS:

All patients underwent polysomnographic examinations; 22 patients (55%) were diagnosed with obstructive sleep apnea and 14 patients (35%) were diagnosed with upper airway resistance syndrome, according to American Sleep Disorders Association criteria. The patients with upper airway resistance syndrome were younger and had a lower body mass index compared with other patients, while there were no difference between the blood pressure levels and the number of antihypertensive drugs. The arousal index was positively correlated with systolic blood pressure level (p = 0.034; r_s = 0.746), while the Epworth score and AHI were independent of disease severity (p = 0.435, r_s = 0.323 and p = 0.819, r_s = -0.097, respectively). Eight patients were treated with positive airway pressure treatment and blood pressure control was achieved in all of them, whereas no pressure reduction was observed in four untreated patients.

CONCLUSIONS:

We conclude that upper airway resistance syndrome is a possible secondary cause of resistant hypertension and that its proper treatment could result in dramatic blood pressure control.     

Obstructive Apneas Induce Early Release of Mesenchymal Stem Cells into Circulating Blood

Study Objectives:

To investigate whether noninvasive application of recurrent airway obstructions induces early release of mesenchymal stem cells into the circulating blood in a rat model of obstructive sleep apnea.

Design:

Prospective controlled animal study.

Setting:

University laboratory.

Patients or Participants:

Twenty male Sprague-Dawley rats (250–300 g).

Interventions:

A specially designed nasal mask was applied to the anesthetized rats. Ten rats were subjected to a pattern of recurrent obstructive apneas (60 per hour, lasting 15 seconds each) for 5 hours. Ten anesthetized rats were used as controls.

Measurements and Results:

Mesenchymal stem cells from the blood and bone marrow samples were isolated and cultured to count the total number of colony-forming unit fibroblasts (CFU-F) of adherent cells after 9 days in culture. The number of CFU-F from circulating blood was significantly (P = 0.02) higher in the rats subjected to recurrent obstructive apneas (5.00 ± 1.16; mean ± SEM) than in controls (1.70 ± 0.72). No significant (P = 0.54) differences were observed in CFU-F from bone marrow.

Conclusions:

Application of a pattern of airway obstructions similar to those experienced by patients with sleep apnea induced an early mobilization of mesenchymal stem cells into circulating blood.

Citation:

Carreras A; Almendros I; Acerbi I; Montserrat JM; Navajas D; Farré R. Obstructive apneas induce early release of mesenchymal stem cells into circulating blood. SLEEP 2009;32(1):117-119.     

Randomized Controlled Trial of Variable-Pressure Versus Fixed-Pressure Continuous Positive Airway Pressure (CPAP) Treatment for Patients with Obstructive Sleep Apnea/Hypopnea Syndrome (OSAHS)

Study Objectives:

To determine whether fixed-pressure or variable-pressure CPAP was preferred by patients and gave better outcomes in patients with the obstructive sleep apnea/hypopnea syndrome (OSAHS).

Design:

Randomized blinded cross-over trial with 6 weeks of fixed and 6 weeks of variable-pressure CPAP

Setting:

Sleep center

Patients:

200 consecutive consenting CPAP naive patients with daytime sleepiness and >15 apneas + hypopneas/h after an attended auto-CPAP titration night.

Interventions:

CPAP therapy using the same device (Autoset Spirit) set for 6 weeks in fixed pressure mode and for 6 weeks in variable pressure mode, the order of therapies being randomized.

Measurements and Results:

All measurements were recorded at the end of each limb by a researcher blind to treatment. These included symptoms, Epworth Score, CPAP usage, objective sleepiness by modified Osler test, vigilance and health related quality of life. A total of 181 of 200 patients completed the study. At the end of the study, patients expressed no significant difference in the primary outcome, patient preference, 72 patients preferring fixed and 69 preferring variable-pressure CPAP. Epworth score was lower on variable (9.5, SEM 0.4) than fixed-pressure CPAP (10.0, SEM 0.3; P = 0.031). Mean CPAP use was higher on variable (4.2, SEM 0.2 h/night) than fixed-pressure CPAP (4.0, SEM 0.2 h/night; P = 0.047). There were no other significant differences between treatments.

Conclusions

This study shows no difference in patient preference and only a marginal benefit of variable over fixed-pressure CPAP in OSAHS in terms of subjective sleepiness and CPAP use. The clinical value of this difference remains to be determined.

Clinical Trial Information:

Variable-pressure versus fixed-pressure continuous positive airway pressure (CPAP) treatment for patients with obstructive sleep apnoea/hypopnoea syndrome (OSAHS); Registration # ISRCTN43085025; http://www.controlled-trials.com/ISRCTN43085025

Citation:

Vennelle M; White S; Riha RL; Mackay T; Engleman HM; Douglas NJ. Randomized controlled trial of variable-pressure versus fixed-pressure continuous positive airway pressure (CPAP) treatment for patients with obstructive sleep apnea/hypopnea syndrome (OSAHS). SLEEP 2010;33(2):267-271.     

Continuous positive airway pressure reduces risk of motor vehicle crash among drivers with obstructive sleep apnea: systematic review and meta-analysis

Context:

Obstructive sleep apnea (OSA) is associated with an increased risk of motor vehicle crash.

Objective:

We performed a systematic review of the literature concerning the impact of continuous positive airway pressure (CPAP) treatment on motor vehicle crash risk among drivers with OSA. The primary objective was to determine whether CPAP use could reduce the risk of motor vehicle crash among drivers with OSA. A secondary objective involved determining the time on treatment required for CPAP to improve driver safety.

Data Sources:

We searched seven electronic databases (MEDLINE, PubMed (PreMEDLINE), EMBASE, PsycINFO, CINAHL, TRIS, and the Cochrane library) and the reference lists of all obtained articles.

Study Selection:

We included studies (before-after, case-control, or cohort) that addressed the stated objectives. We evaluated the quality of each study and the interplay between the quality, quantity, robustness, and consistency of the evidence. We also tested for publication bias.

Data Extraction:

Data were extracted by two independent analysts. When appropriate, data were combined in a fixed or random effects meta-analysis.

Results:

A meta-analysis of 9 observational studies examining crash risk of drivers with OSA pre- vs. post-CPAP found a significant risk reduction following treatment (risk ratio = 0.278, 95% CI: 0.22 to 0.35; P < 0.001). Although crash data are not available to assess the time course of change, daytime sleepiness improves significantly following a single night of treatment, and simulated driving performance improves significantly within 2 to 7 days of CPAP treatment.

Conclusions:

Observational studies indicate that CPAP reduces motor vehicle crash risk among drivers with OSA.

Citation:

Tregear S; Reston J; Schoelles K; Phillips B. Continuous positive airway pressure reduces risk of motor vehicle crash among drivers with obstructive sleep apnea. SLEEP 2010;33(10):1373-1380.     

Electrical impedance tomography to evaluate air distribution prior to extubation in very-low-birth-weight infants: a feasibility study

OBJECTIVES:

Nasal continuous positive airway pressure is used as a standard of care after extubation in very-low-birth-weight infants. A pressure of 5 cmH₂O is usually applied regardless of individual differences in lung compliance. Current methods for evaluation of lung compliance and air distribution in the lungs are thus imprecise for preterm infants. This study used electrical impedance tomography to determine the feasibility of evaluating the positive end-expiratory pressure level associated with a more homogeneous air distribution within the lungs before extubation.

METHODS:

Ventilation homogeneity was defined by electrical impedance tomography as the ratio of ventilation between dependent and non-dependent lung areas. The best ventilation homogeneity was achieved when this ratio was equal to 1. Just before extubation, decremental expiratory pressure levels were applied (8, 7, 6 and 5 cmH₂0; 3 minutes each step), and the pressure that determined the best ventilation homogeneity was defined as the best positive end-expiratory pressure.

RESULTS:

The best positive end-expiratory pressure value was 6.3±1.1 cmH₂0, and the mean continuous positive airway pressure applied after extubation was 5.2±0.4 cmH₂0 (p = 0.002). The extubation failure rate was 21.4%. X-Ray and blood gases after extubation were also checked.

CONCLUSION:

This study demonstrates that electrical impedance tomography can be safely and successfully used in patients ready for extubation to suggest the best ventilation homogeneity, which is influenced by the level of expiratory pressure applied. In this feasibility study, the best lung compliance was found with pressure levels higher than the continuous positive airway pressure levels that are usually applied for routine extubation.     

Upper Airway Collapsibility During REM Sleep in Children with the Obstructive Sleep Apnea Syndrome

Study Objectives:

In children, most obstructive events occur during rapid eye movement (REM) sleep. We hypothesized that children with the obstructive sleep apnea syndrome (OSAS), in contrast to age-matched control subjects, would not maintain airflow in the face of an upper airway inspiratory pressure drop during REM sleep.

Design:

During slow wave sleep (SWS) and REM sleep, we measured airflow, inspiratory time, inspiratory time/total respiratory cycle time, respiratory rate, tidal volume, and minute ventilation at a holding pressure at which flow limitation occurred and at 5 cm H₂O below the holding pressure in children with OSAS and in control subjects.

Setting:

Sleep laboratory.

Participants:

Fourteen children with OSAS and 23 normal control subjects.

Results:

In both sleep states, control subjects were able to maintain airflow, whereas subjects with OSAS preserved airflow in SWS but had a significant decrease in airflow during REM sleep (change in airflow of 18.58 ± 12.41 mL/s for control subjects vs −44.33 ± 14.09 mL/s for children with OSAS, P = 0.002). Although tidal volume decreased, patients with OSAS were able to maintain minute ventilation by increasing the respiratory rate and also had an increase in inspiratory time and inspiratory time per total respiratory cycle time

Conclusion:

Children with OSAS do not maintain airflow in the face of upper-airway inspiratory-pressure drops during REM sleep, indicating a more collapsible upper airway, compared with that of control subjects during REM sleep. However, compensatory mechanisms exist to maintain minute ventilation. Local reflexes, central control mechanisms, or both reflexes and control mechanisms need to be further explored to better understand the pathophysiology of this abnormality and the compensation mechanism.

Citation:

Huang J; Karamessinis LR; Pepe ME; Glinka SM; Samuel JM; Gallagher PR; Marcus CL. Upper airway collapsibility during REM sleep in children with the obstructive sleep apnea syndrome. SLEEP 2009;32(9):1173-1181.     

Upper airway surface tension but not upper airway collapsibility is elevated in primary Sjögren's syndrome

Study Objectives:

Primary Sjögren''s syndrome is an autoimmune disease typified by xerostomia (dry mouth) that, in turn, could lead to increased saliva surface tension (γ) and increased upper airway collapsibility. Fatigue, of unknown etiology, is also frequently reported by patients with primary Sjögren''s syndrome. Recent preliminary data indicate a high prevalence of obstructive sleep apnea in healthy-weight women with primary Sjögren''s syndrome. Concurrent research highlights a significant role of γ in the maintenance of upper airway patency. The aim of this study was to compare oral mucosal wetness, saliva γ, and upper airway collapsibility during wake and sleep between women with primary Sjögren''s syndrome and matched control subjects.

Setting:

Participants slept in a sound-insulated room with physiologic measurements controlled from an adjacent room.

Participants:

Eleven women with primary Sjögren''s syndrome and 8 age- and body mass index-matched control women.

Interventions:

Upper airway collapsibility index (minimum choanal-epiglottic pressure expressed as a percentage of delivered choanal pressure) was determined from brief negative-pressure pulses delivered to the upper airway during early inspiration in wakefulness and sleep.

Measurements and Results:

Patients with primary Sjögren''s syndrome had significantly higher saliva γ (“pull-off” force method) compared with control subjects (67.2 ± 1.1 mN/m versus 63.2 ± 1.7 mN/m, P < 0.05). Upper airway collapsibility index significantly increased from wake to sleep (Stage 2 and slow wave sleep) but was not different between groups during wake (primary Sjögren''s syndrome versus controls; 36.3% ± 8.0% vs 46.0 ± 13.8%), stage 2 sleep (53.1% ± 11.9% vs 63.4% ± 7.2%), or slow-wave sleep (60.8% ± 12.2% vs 60.5% ± 9.3%).

Conclusions:

Despite having a significantly “stickier” upper airway, patients with primary Sjögren''s syndrome do not appear to have abnormal upper airway collapsibility, at least as determined from upper airway collapsibility index.

Citation:

Hilditch CJ; McEvoy RD; George KE; Thompson CC; Ryan MK; Rischmueller M; Catcheside PG. Upper airway surface tension but not upper airway collapsibility is elevated in primary Sjögren''s syndrome. SLEEP 2008;31(3):367-374.     

Initial respiratory management in preterm infants and bronchopulmonary dysplasia

BACKGROUND:

Ventilator injury has been implicated in the pathogenesis of bronchopulmonary dysplasia. Avoiding invasive ventilation could reduce lung injury, and early respiratory management may affect pulmonary outcomes.

OBJECTIVE:

To analyze the effect of initial respiratory support on survival without bronchopulmonary dysplasia at a gestational age of 36 weeks.

DESIGN/METHODS:

A prospective 3-year observational study. Preterm infants of <32 weeks gestational age were classified into 4 groups according to the support needed during the first 2 hours of life: room air, nasal continuous positive airway pressure, intubation/surfactant/extubation and prolonged mechanical ventilation (defined as needing mechanical ventilation for more than 2 hours).

RESULTS:

Of the 329 eligible patients, a total of 49% did not need intubation, and 68.4% did not require prolonged mechanical ventilation. At a gestational age of 26 weeks, there was a significant correlation between survival without bronchopulmonary dysplasia and initial respiratory support. Preterm infants requiring mechanical ventilation showed a higher risk of death and bronchopulmonary dysplasia. After controlling for gestational age, antenatal corticosteroid use, maternal preeclampsia and chorioamnionitis, the survival rate without bronchopulmonary dysplasia remained significantly lower in the mechanically ventilated group.

CONCLUSIONS:

In our population, the need for more than 2 hours of mechanical ventilation predicted the development of bronchopulmonary dysplasia in preterm infants with a gestational age >26 weeks (sensitivity = 89.5% and specificity = 67%). The need for prolonged mechanical ventilation could be an early marker for the development of bronchopulmonary dysplasia. This finding could help identify a target population with a high risk of chronic lung disease. Future research is needed to determine other strategies to prevent bronchopulmonary dysplasia in this high-risk group of patients.     

Diastolic function and functional capacity after a single session of continuous positive airway pressure in patients with compensated heart failure

OBJECTIVE:

The effects of acute continuous positive airway pressure therapy on left ventricular diastolic function and functional capacity in patients with compensated systolic heart failure remain unclear.

METHODS:

This randomized, double-blind, placebo-controlled clinical trial included 43 patients with heart failure and a left ventricular ejection fraction <0.50 who were in functional classes I-III according to the New York Heart Association criteria. Twenty-three patients were assigned to continuous positive airway pressure therapy (10 cmH₂O), while 20 patients received placebo with null pressure for 30 minutes. All patients underwent a 6-minute walk test (6MWT) and Doppler echocardiography before and immediately after intervention. Clinicaltrials.gov: {"type":"clinical-trial","attrs":{"text":"NCT01088854","term_id":"NCT01088854"}}NCT01088854.

RESULTS:

The groups had similar clinical and echocardiographic baseline variables. Variation in the diastolic function index (e′) after intervention was associated with differences in the distance walked in both groups. However, in the continuous positive airway pressure group, this difference was greater (continuous positive airway pressure group: Δ6MWT = 9.44+16.05×Δe′, p = 0.002; sham group: Δ6MWT = 7.49+5.38×Δe′; p = 0.015). There was a statistically significant interaction between e′ index variation and continuous positive airway pressure for the improvement of functional capacity (p = 0.020).

CONCLUSIONS:

Continuous positive airway pressure does not acurately change the echocardiographic indexes of left ventricle systolic or diastolic function in patients with compensated systolic heart failure. However, 30-minute continuous positive airway pressure therapy appears to have an effect on left ventricular diastolic function by increasing functional capacity.     

Positive airway pressure adherence in veterans with posttraumatic stress disorder

Study Objectives:

To determine the short-term positive airway pressure (PAP) adherence rates and to identify non–mask-related risk factors associated with 30-day nonadherence to PAP in a population of veterans with obstructive sleep apnea (OSA) and posttraumatic stress disorder (PTSD).

Design:

A retrospective study.

Settings:

A Veterans Affairs hospital.

Patients:

One hundred forty-eight PTSD veterans newly diagnosed with OSA and a control group of OSA without PTSD matched for age, gender, BMI, and severity of OSA.

Interventions:

N/A

Measurements and Results:

At 30-day follow-up, adherence to PAP was significantly lower in the PTSD group compared to the control group (41% versus 70%, respectively; P < 0.001). Veterans with adequate PAP adherence were more likely to experience sleepiness at baseline compared to nonadherent subjects (ESS 14.4 ± 5.3 versus 12.3 ± 5.9, respectively; P = 0.04). Nightmares were more frequently reported in those who were PAP nonadherent (P = 0.002). Mask discomfort, claustrophobia, and air hunger were the reported reasons for PAP nonadherence in the PTSD group.

Conclusion:

PAP usage and adherence were lower in PTSD veterans with OSA than veterans without PTSD. Excessive sleepiness predicted PAP adherence while frequent nightmares were correlated with poor adherence to PAP therapy.

Citation:

El-Solh AA; Ayyar L; Akinnusi M; Relia S; Akinnusi O. Positive airway pressure adherence in veterans with posttraumatic stress disorder. SLEEP 2010;33(11):1495-1500.     

Hypoadiponectinemia is Related to Sympathetic Activation and Severity of Obstructive Sleep Apnea

Study Objectives:

Hypoadiponectinemia is associated with cardiovascular morbidity and diabetes mellitus. We hypothesize that adiponectin may be downregulated in sleep apnea through various mechanisms, contributing to cardiometabolic risks. This study investigated the relationship between serum adiponectin and sleep disordered breathing and its potential determinants.

Design:

Cross-sectional study.

Subjects and setting:

Adult men without prevailing medical comorbidity from the sleep clinic in a teaching hospital.

Measurements & Results:

One hundred thirty-four men underwent polysomnography, with mean age of 43.9 (9.8) years, and median apnea-hypopnea index (AHI) of 17.1 (5.7, 46.6). Overnight urine samples for catecholamines and blood samples for analyses of insulin, glucose and adiponectin levels from fasting subjects were taken. Insulin resistance was estimated by homeostasis model assessment (HOMA-IR). Magnetic resonance imaging was performed to quantify the amount of abdominal visceral fat. Serum adiponectin level, adjusted for age, body mass index, and visceral fat volume, was significantly lower in subjects with severe obstructive sleep apnea (AHI ≥ 30) compared with those with an AHI of less than 30: 4.0 (3.1, 5.4) versus 5.4 (3.6, 7.9) μg/mL, P = 0.039. After we adjusted for adiposity, adiponectin levels remained negatively correlated with AHI (P = 0.037), arousal index (P = 0.022), HOMA-IR/fasting insulin (P < 0.001), and urinary norepinephrine and normetanephrine (P < 0.008). In a multiple stepwise regression model, the independent determinants of adiponectin after adjustment for adiposity were HOMA-IR (P < 0.001) and urinary norepinephrine and normetanephrine (P = 0.037).

Conclusions:

Adiponectin was suppressed in subjects with severe obstructive sleep apnea, independent of obesity. Adiponectin levels were determined by insulin resistance and sympathetic activation, factors that may be totally or partially attributed to sleep disordered breathing.

Citation:

Lam JCM; Xu A; Tam S; Khong PL; Yao TJ; Lam DCL; Lai AYK; Lam B; Lam KSL; Ip MSM. Hypoadiponectinemia is related to sympathetic activation and severity of obstructive sleep apnea. SLEEP 2008;31(12):1721–1727.     

Tonsil volume,tonsil grade and obstructive sleep apnea: is there any meaningful correlation?

OBJECTIVES:

The aims of this study were to evaluate the correlation between oropharyngeal examination and objective palatine tonsil volume in snoring adults and verify the influence of the oropharyngeal anatomy, body mass index, age, and severity of obstructive sleep apnea on actual tonsil volume. In addition, we aimed to assess the influence of tonsil size on obstructive sleep apnea in adults.

INTRODUCTION:

Pharyngeal wall geometry is often altered in adults who have obstructive sleep apnea, and this might influence the findings of the oropharyngeal examination that, in turn, are the key factors when considering surgical management for this condition. Furthermore, the correlation between the actual tonsil volume and the severity of obstructive sleep apnea in adults is currently unknown.

METHODS:

We prospectively studied 130 patients with obstructive sleep apnea or primary snoring who underwent pharyngeal surgery with intraoperative measurement of tonsil volume. We compared tonsil volume with preoperative polysomnography, oropharyngeal examination, and anthropometric data.

RESULTS:

We found a significant correlation between actual tonsil volume and subjective tonsil grade. We also found a significant correlation between tonsil volume and the apnea-hypopnea index. Using a multivariate linear regression model, tonsil volume was found to be significantly correlated with age, body mass index, and oropharyngeal examination, but not with polysomnography. Clinically, only the rare tonsil grade IV was indicative of more severe obstructive sleep apnea.

CONCLUSIONS:

There is a strong correlation between clinical tonsil grade and objective tonsil volume in snoring adults, and this correlation exists regardless of the presence or severity of obstructive sleep apnea. Pharyngeal tissue volume likely reflects the body mass index rather than obstructive sleep apnea severity.