Nasal pressure recording in the diagnosis of sleep apnoea hypopnoea syndrome. (25/1461)

BACKGROUND: Nasal pressure tracing is now being used to measure breathing in ambulatory screening devices for sleep apnoea but it has not been compared with other methods of assessment. METHODS: Sleep induced breathing disorders were scored by three different methods of analysis (thermistry, inductive plethysmography, and nasal pressure tracing) in 193 consecutive patients referred to our sleep laboratory. With the conventional thermistry method an apnoea was defined as the absence of oronasal flow on the thermistor signal for >/=10 s and a hypopnoea as a 50% decrease in the sum signal of inductive plethysmography tracing for >/=10 s associated with an arousal and/or a 2% decrease in SaO2. Nasal pressure was measured via nasal prongs connected to a pressure transducer. Using the thermistor signal alone, a hypopnoea was defined as a 50% decrease in the signal for >/=10 s associated with an arousal and/or a 2% decrease in SaO2. A similar definition of apnoea and hypopnoea was used for nasal pressure, the fall in pressure being substituted for the thermistor reading. RESULTS: Impaired nasal ventilation prevented adequate measurements of nasal pressure in 9% of subjects. According to the conventional method of interpretation 107 subjects were identified as having the sleep apnoea hypopnoea syndrome (SAHS). The apnoea + hypopnoea index (AHI) was significantly lower using the thermistry method than with conventional analysis (mean difference -4.3/h, 95% CI -5.3 to -3.2, p<10(-4)); 39% of conventional hypopnoeic events were scored as apnoeas using nasal pressure scoring. Apnoeic and hypopnoeic events could also be observed without any change in thermistor and sum Respitrace signals that resumed with the occurrence of arousals or awakenings. The AHI was significantly higher with nasal pressure scoring than with the conventional method (mean difference 4.5, 95% CI 3.4 to 5.6, p<10(-4)). The mean difference in apnoea index between conventional and nasal pressure scoring was -7.5/h (95% CI -8.9 to -6.1). In the 78 patients who did not have SAHS according to the conventional method of analysis there was a significant positive relationship between the arousal index and AHI measured by nasal pressure tracing (R = 0.51, p<10(-4)). Seventeen of the 78 patients had an AHI of >15/h by the nasal pressure method of analysis. CONCLUSIONS: Nasal pressure recording provides a simple and reliable measurement of nocturnal breathing abnormalities and may identify breathing abnormalities associated with arousals that are missed by other diagnostic methods.  (+info)

Neuromechanical interaction in human snoring and upper airway obstruction. (26/1461)

The fact that snoring and obstructive apnea only occur during sleep means that effective neuromuscular functioning of the upper airway during sleep is vital for the maintenance of unimpeded breathing. Recent clinical studies in humans have obtained evidence demonstrating that upper airway neural receptors sense the negative pressure generated by inspiration and "trigger," with a certain delay, reflex muscle activation to sustain the airway that might otherwise collapse. These findings have enabled us to propose a model in which the mechanics is coupled to the neuromuscular physiology through the generation of reflex wall stiffening proportional to the retarded fluid pressure. Preliminary results on this model exhibit three kinds of behavior typical of unimpeded breathing, snoring, and obstructive sleep apnea, respectively. We suggest that the increased latency of the reflex muscle activation in sleep, together with the reduced strength of the reflex, have important clinical consequences.  (+info)

Nocturnal oxygen desaturation in coronary artery disease. (27/1461)

Nocturnal oxygen desaturation and sleep apnea may provoke myocardial ischemia and arrhythmias in patients with coronary artery disease (CAD). Additionally, these factors may accelerate coronary atherosclerosis in the long term and they may play a role in the progression of the disease process. On the other hand, studies related to this subject are limited. This study was conducted to investigate the nocturnal oxygen desaturation and apneas during sleep in patients with CAD and to assess the possible association of these factors with CAD. We studied 22 male patients with CAD confirmed by coronary angiography who did not have symptomatic pulmonary disease and fourteen male healthy controls without known heart disease. Patients were randomly selected from men undergoing coronary angiography. Controls were age and sex matched and selected from the population registry. The normal controls were of similar body mass index to the patients. None of them were obese. The patients and controls underwent standard polysomnography. Men with CAD and controls had a similar apnea-hypopnea index (2.3 +/- 3.8 vs. 1.2 +/- 1.7). Mean oxygen desaturation index was higher among patients than controls (2.1 vs. 0.5, p < 0.05). Patients with CAD spent 3.1% (9.7 +/- 13.6) of total sleep time desaturated, while the same proportion in controls were 0.5% (1.9 +/- 4.1)(p < 0.05). Although both groups of patients were of similar heart rates at initial, the development of bradycardia during sleep was significantly higher in patients compared with controls (43.3% vs. 25.3%, p < 0.05). The results demonstrate that sleep disordered breathing, in particular nocturnal oxygen desaturation, occurs more common in patients with CAD compared to controls. Additionally, patients are at higher risk of developing bradycardia during sleep. This findings suggest that oxygen desaturation during sleep might contribute to the progression of CAD.  (+info)

Obstructive sleep apnea syndrome: an experience in Chinese adults in Hong Kong. (28/1461)

OBJECTIVE: Epidemiologic studies in Caucasian populations suggested that symptomatic obstructive sleep apnea (OSA) occurred at a prevalence of 1-10%. The condition has been increasingly recognised among the Chinese in Hong Kong. We therefore, summarize our experience with OSA at the Department of Medicine, The University of Hong Kong at Queen Mary Hospital from 1985-1996. METHODS: All clinic records concerning demographic data, anthropometric data, clinical features, polysomnographic findings and treatment were reviewed. RESULTS: One hundred and twenty-two patients were diagnosed to have OSA. Demographic and clinical features were similar to Caucasian data with a male predominance of 84%, a mean age of about 50 years, and obesity as a risk factor at a mean body mass index of 30.4, which was higher than that of the average local population, although lower than that of OSA patients in Caucasian series. About 27% of the patients have a body mass index (BMI) similar to or below the population average. Nearly all were habitual snorers, and the majority had excessive daytime sleepiness. On polysomnography, the mean apnea-hypopnea index was 38. Common associated medical conditions were hypertension (34%), diabetes mellitus (10%), ischemic heart disease (9%), hyperlipidemia (6%). Most patients were managed successfully with nasal continuous positive airway pressure. Treatment with oral appliances for milder cases is being explored. CONCLUSIONS: OSA has been increasingly recognised among Chinese adults in Hong Kong in the past decade. Demographic features were similar to Caucasian data. The majority of patients were overweight, although 27% were not, and further investigation on the contribution of faciomaxillary morphology to OSA in this group is warranted.  (+info)

Obstructive sleep apnoea syndrome in hereditary gelsolin-related amyloidosis. (29/1461)

Gelsolin-related amyloidosis (AGel amyloidosis) is a rare autosomal dominant disorder, reported worldwide in kindreds carrying a G654A or G654T gelsolin gene mutation. The main clinical signs are cutis laxa, cranial and peripheral neuropathy, and corneal lattice dystrophy but heavy intermittent snoring also occurs. To evaluate whether sleep apnoea is present we performed nocturnal sleep recordings, cephalometric and spirometric analyses and multiple sleep latency tests (MSLT) in five snoring patients with a G654A gelsolin gene mutation. Four patients had obstructive sleep apnoea syndrome (OSAS) with redundant oropharyngeal and hypopharyngeal soft tissues, macroglossia and cranial neuromuscular dysfunction. The fifth patient had hypersomnia without obstructive sleep apnoea. Nasal continuous positive airway pressure (CPAP) was an effective treatment. This study presents the first evidence in favour of an association between AGel amyloidosis and OSAS, but further studies are needed to define the prevalence of OSAS and the pathogenetic roles of amyloid and variant gelsolin in its evolution.  (+info)

Increased levels of circulating ICAM-1, VCAM-1, and L-selectin in obstructive sleep apnea syndrome. (30/1461)

Obstructive sleep apnea syndrome (OSAS) may be one of the most important risk factors of cardiovascular disorders, although the exact mechanism remains to be elucidated. In the present study, we hypothesized that OSAS-induced hypoxic stress might be involved in the etiology of cardiovascular disorders by activating adhesion molecules, including intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion molecule 1 (VCAM-1), and L-selectin. To examine this hypothesis, we measured circulating ICAM-1, VCAM-1, and L-selectin levels before and after sleep in OSAS patients and age-matched controls. The circulating ICAM-1, VCAM-1, and L-selectin levels increased in the OSAS patients before sleep compared with the normal subjects (ICAM-1: 392.9 +/- 48.5 vs. 201.2 +/- 55.0 ng/ml, P < 0.05; VCAM-1: 811.0 +/- 87.8 vs. 574.2 +/- 42.7 ng/ml, P < 0.05; L-selectin: 1,386.6 +/- 77.9 vs. 1,038.8 +/- 78.6 ng/ml, P < 0.01, respectively). After sleep, significantly greater levels of ICAM-1 and L-selectin, but not VCAM-1, were observed in the OSAS group. These observations suggest that OSAS-induced hypoxia activates adhesion molecules, resulting in the important risk factor of cardiovascular disorders. Treatment of OSAS can be, therefore, a potential approach to prevention of cardiovascular events.  (+info)

Monitoring respiratory function and sleep in the obese Vietnamese pot-bellied pig. (31/1461)

Development of drug treatments for obstructive sleep-disordered breathing has been impeded by the lack of animal models. The obese pig may be a suitable animal model, as it has been reported to experience sleep-disordered breathing resembling human obstructive sleep apnea. The purpose of this paper is to describe in detail techniques for chronic instrumentation of the obese Vietnamese pot-bellied pig and to study respiratory function during sleep. Under general anesthesia, four obese pigs were instrumented for long-term recording of intrapleural and tracheal pressures, genioglossal EMG, and bioelectric signals related to sleep. A custom-fitted face mask was used to record respiratory variables including airflow, snoring, and expired CO(2). Most chronic instrumentation provided robust signals for up to 6 wk after installation. All pigs displayed sleep-disordered breathing characterized by increased resistance to airflow, snoring, inspiratory flow limitation, and possible sleep disruption. Apneas and hypopneas were not a feature of breathing during sleep in these animals. Nonetheless, this animal preparation may be useful for exploring possible drug treatments for obstructive sleep-disordered breathing.  (+info)

Effect of high versus low ambient humidity on the severity of obstructive sleep apnoea. (32/1461)

BACKGROUND: Surface tension forces appear to make a significant contribution to upper airway closure in patients with obstructive sleep apnoea (OSA). It is possible that drying of the upper airway mucosa at night might contribute to these surface tension forces and the severity of OSA might therefore change with alteration of the ambient humidity. METHODS: A randomised single blind crossover study of high ambient relative humidity (HRH) versus low ambient relative humidity (LRH) was performed in 12 men of mean (SD) age 49 (9) years with mild OSA (apnoea/hypopnoea index (AHI) 14 (5.2)). On one night patients slept in continuous HRH (85 (4)%, range 80-93%) and on the other in LRH (16 (4)%, range 11-22%). RESULTS: The AHI was similar on the HRH and LRH nights (mean difference 3; 95% CI -2 to 9, p = 0.20 and no statistically significant differences in AHI were observed on the two nights after standardising for body position and sleep stage. Sleep stage distribution and the proportion of time spent in the supine position were similar on the HRH and LRH nights. The number of non-respiratory arousals was also similar on the two nights. CONCLUSION: Altering ambient humidity alone has no significant impact on the severity of OSA.  (+info)