A prospective polysomnographic study on the evolution of complex sleep apnoea.

Complex sleep apnoea (CompSA) may be observed following continuous positive airway pressure (CPAP) treatment. In a prospective study, 675 obstructive sleep apnoea patients (mean age 55.9 yrs; 13.9% female) participated. Full-night polysomnography was performed at diagnosis, during the first night with stable CPAP and after 3 months of CPAP. 12.2% (82 out of 675 patients) had initial CompSA. 28 of those were lost to follow-up. Only 14 out of the remaining 54 patients continued to satisfy criteria for CompSA at follow-up. 16 out of 382 patients not initially diagnosed with CompSA exhibited novel CompSA after 3 months. 30 (6.9%) out of 436 patients had follow-up CompSA. Individuals with CompSA were 5 yrs older and 40% had coronary artery disease. At diagnosis, they had similar sleep quality but more central and mixed apnoeas. On the first CPAP night and at follow-up, sleep quality was impaired (more wakefulness after sleep onset) for patients with CompSA. Sleepiness was improved with CPAP, and was similar for patients with or without CompSA at diagnosis and follow-up. CompSA is not stable over time and is mainly observed in predisposed patients on nights with impaired sleep quality. It remains unclear to what extent sleep impairment is cause or effect of CompSA.

[Measuring sleep duration and sleep quality]. / Messung von Schlafdauer und Schlafqualität.

Restorative functions of sleep are of special interest for sleep medicine. For the assessment of these restorative functions, various parameters are taken into account, among which sleep duration and sleep quality play the most important roles. Both terms are essential for sleep perception, expressing the subjective satisfaction of the individual with the time spent asleep. In recent decades, sleep medicine and sleep research have developed methods for the assessment of both objective and subjective dimensions of sleep. Among subjective methods, taking of the medical history focusing on the patient's sleep is important. Standardized and validated questionnaires play a supportive role. Objective methods are, for example, estimation of the sleep-wake cycle by means of actigraphy and polygraphy. Especially in multimorbid patients, polysomnography is still the gold standard method for diagnostics. An important approach during recent years is shifting from bothering overnight examinations into less disturbing procedures for patients that include performing ambulatory, outpatient examinations in the patients' home rather than inpatient surveillance within sleep centers.

Sleep-related myocardial ischemia and sleep structure in patients with obstructive sleep apnea and coronary heart disease.

STUDY OBJECTIVES: Patients with coronary heart disease (CHD) and obstructive sleep apnea may have an increased cardiac risk due to nocturnal myocardial ischemia triggered by apnea-associated oxygen desaturation. Sleep structure in patients with obstructive sleep apnea is fragmented by activation of the central nervous system (CNS) (arousal) due to obstructive apneas. Nocturnal myocardial ischemia may lead to activation of the CNS as well. PATIENTS: Fourteen patients with obstructive sleep apnea and CHD disease and seven patients suffering from obstructive sleep apnea without CHD were studied. Overnight sleep studies and simultaneous six-lead ECG recordings were performed. In addition, sleep studies and ECG recordings were performed with administration of a sustained-release nitrate in these patients in a double-blinded crossover design. RESULTS: Analysis of three nights' recordings revealed 144 episodes of nocturnal myocardial ischemia in six subjects. Five patients had underlying CHD and one patient exhibited diffuse wall defects of the coronary arteries; also, 85.4% of ischemic episodes were concomitant with apneas and oxygen desaturation > 3%, and 77.8% of ischemic episodes occurred during rapid eye movement (REM) sleep, although total amount of REM sleep was only 18% of total sleep time. Mean oxygen saturation was significantly lower (p < 0.05) during apnea-associated ischemic episodes than during nonapnea-associated ischemia (77.3% vs 93.1%). Nitrate administration did not reduce ischemic episodes. Sleep architecture (macrostructure) exhibited a reduction in sleep stages non-REM 3 and 4 and REM sleep. Comparing the microstructure of sleep (arousals) within episodes with and without ischemia but similar criteria like sleep stage, apnea activity, and oxygen saturation, we found significantly more (p < 0.01) and severe (p < 0.001) arousals during periods with myocardial ischemia than during control episodes. In addition, microstructure of sleep was disturbed by myocardial ischemia itself in absence of apneas. CONCLUSION: It is concluded that patients with CHD and obstructive sleep apnea are endangered by apnea-associated ischemia and that these ischemic episodes lead to activation of the CNS and additional fragmentation of sleep. Patients with nocturnal ischemia should be screened for underlying sleep apnea even if nitrate therapy fails.

Association between blood pressure reduction with antihypertensive treatment and sleep apnea activity.

This study investigated whether a drug therapy-induced reduction in nocturnal blood pressure (BP) was associated with decreased sleep apnea activity. Two polysomnographies from 54 hospitalized male hypertensive, obstructive sleep apnea patients were analyzed in a double-blind, randomized, parallel-group trial of the angiotensin-converting enzyme inhibitor cilazapril (C), 2.5 mg once daily, or placebo (P). Blood pressure was measured by means of an intra-arterial catheter. Compared with P, C lowered mean arterial BP during non-rapid eye movement (NREM) (-8.3 +/- 10.7 mm Hg, P = .05) and REM sleep (-8.6 +/- 10.1 mm Hg, P = .02). Respiratory disturbance index (-8.6 +/- 3.2 events/h of sleep (n/h), P = .01) and apnea index (AI) (-6.6 +/- 3.0 n/h, P = .04) during NREM sleep were lowered by C and, to a lesser extent, by P (-5.9 +/- 3.2 n/h, P = .07 and -5.0 +/- 3.6 n/h, P = .18, respectively). The effect on AI and hypopnea index (HI) during REM sleep was not significant for C (-5.9 +/- 3.4 and 0.1 +/- 2.0, NS, respectively) and P (-2.6 +/- 3.9 and 1.6 +/- 2.0, NS, respectively). There was a significant linear correlation between the change in REM systolic BP and the change in REM AI (r = 0.28, P = .04); the mean BP change correlated negatively with the change in HI (-0.28, P = .04). During NREM sleep there was no significant correlation between changes in BP and the treatment effects on sleep apnea activity. Blood pressure reduction after short-term antihypertensive treatment did not affect sleep disordered breathing during NREM sleep. Reduced BP was associated with a weak reduction of AI and a slight increase of HI during REM sleep. It appears that elevated BP contributes only marginally to sleep apnea severity in hypertensive patients with obstructive sleep apnea.

Coronary heart disease and upper airway obstruction.

Coronary heart disease (CHD) is a leading cause of death among middle-aged men. In the same age group the spectrum of upper airway obstruction from habitual snoring to obstructive sleep apnoea syndrome (OSAS) is frequent. In several studies snoring was found to be an important risk factor for ischaemic heart disease. The prevalence of OSAS in patients with CHD, profile of risk factors and ventricular arrhythmias was determined in a prospective manner in 78 patients with stenosis of one or more coronary arteries at coronary arterography. OSAS was found in 27 patients (34.6%). Mean respiratory disturbance index (RDI) was 23.9. RDI increased with higher age. No significant differences in both groups could be found in ventricular arrhythmias, left ventricular ejection fraction and risk factors, except hyperuricaemia and adiposity. OSAS is frequent in patients with CHD and may be an additional risk factor besides the known coronary risk factors. Patients with the combination of CHD and OSAS have to be regarded as a group at particular risk because of several interactions between OSAS and coronary haemodynamics. Furthermore the microstructure of sleep in patients with nocturnal myocardial ischaemia is disturbed.

Arterial hypertension and sleep apnoea: effect of the angiotensin-converting enzyme (ACE) inhibitor cilazapril on continuously measured blood pressure during sleep and wakefulness.

Male patients with arterial hypertension and obstructive sleep-related breathing disorders (mean age 50 y, Body Mass Index (BMI) 32.4 kg m-2, Respiratory Disturbance Index (RDI) 47.2 and systolic/diastolic blood pressure (SBD/DBD) 162/103 mmHg) were examined before and after 8 days of treatment with the long-acting angiotensin-converting-enzyme (ACE) inhibitor cilazapril 2.5 mg vs. placebo in a double-blind design with parallel groups. Cardiorespiratory polysomnography was carried out at night; during daytime wakefulness patients submitted to examinations of physical and mental exertion. Cilazapril reduced the mean pressure during the entire examination period (day and night) by 9.55 (SD +/- 7.13) mmHg, compared to 4.57 (SD +/- 7.20) mmHg for placebo (P < 0.006), independently from systematic changes of heart rate (x = -3.3 and -3.5 bpm, respectively). During REM sleep, mean arterial pressure was significantly reduced by 8.63 (SD +/- 10.1) mmHg, compared to a reduction on placebo of 3.17 (SD 9.6) mmHg (P = 0.023). Under psychometric strain, the mean arterial pressure was reduced by 15.31 (SD +/- 8.7) mmHg with cilazapril; under placebo medication by 6.19 (SD +/- 7.3) mmHg (P < 0.0001). Heart rate was not significantly changed.

Intrathoracic pressure changes and cardiovascular effects induced by nCPAP and nBiPAP in sleep apnoea patients.

The effect of nasal continuous positive airway pressure (nCPAP) and nasal bi-level positive airway pressure (nBiPAP) on intrathoracic pressure and haemodynamics during wakefulness was studied in a group of nine patients with severe sleep apnoea. No patient took cardiovascular medication. Patients were studied with a Swan Ganz catheter, an arterial line and an oesophageal balloon. nCPAP and nBiPAP were applied in the following pressure sequence: 5, 10 and 15 cm H2O of CPAP and 10/5 and 15/10 cm H2O of nBiPAP. Measurements were made at the end of a 5-min period at each pressure level. Intrathoracic pressure was noted to increase to a level of approximately 50% of the pressure delivered at the mask. At a CPAP of 10 cm H2O and above, as well as at BiPAP of 10/5 or higher, there was a decrease in cardiac output (CO) and cardiac index (CI). CI fell below the normal value in two of the patients. Transmural pulmonary artery pressure (PPAtm) decreased at a CPAP of 15 cm H2O and at both BiPAP levels. Transmural right atrial pressure (PRAtm) decreased at both BiPAP levels. There were no differences in CO, CI, PPAtm and PRAtm between nCPAP and nBiPAP at equal inspiratory pressures. SaO2 increased during BiPAP 15/10 cm H2O, whereas heart rate and arterial blood pressure did not change significantly. The data presented here are consistent with the literature on positive end-expiratory pressure (PEEP) applied via intratracheal tube and are likely to be due to a reduced venous return. It is concluded that nasally applied positive pressure may have acute negative effects on cardiac function in patients with sleep apnoea.

REM-sleep-hypertension in obstructive sleep apnea.

Previous investigations involving continuous blood pressure (BP) monitoring have shown an important alteration of the 24-hour BP profile in patients with obstructive sleep apnea syndrome (OSAS). We investigated the impact of REM sleep on the 24-hour BP cycle in 16 severe OSAS male patients (mean respiratory disturbance index = 66 +/- 16 events/hour of sleep), with hypertension (mean BP 162 +/- 21/105 +/- 11 mmHg World Health Organization (WHO) protocol). Two successive nights of polysomnography were performed, and arterial BP was monitored continuously during the second 24-hour period after brachial artery cannulation. During the daytime, subjects were kept awake and supine. At 3 p.m. BP was continuously monitored during quiet supine wakefulness for 20 minutes. Systolic, diastolic and mean BP and heart rate (HR) were analyzed and tabulated in mean values of 5 minute segments. Sleep/wake information were correlated with cardiovascular variables. Each uninterrupted REM sleep period was identified and comparison between the period of quiet supine wakefulness and REM sleep HR and BP values was performed. 8 OSAS patients presented a normal drop of the mean arterial BP during the nocturnal REM sleep periods compared to quiet supine wakefulness (mean value = -10.8 +/- 7.3 mmHg) ("dippers") while the other 8 subjects ("REM sleep non dippers"), revealed an elevated mean arterial BP during REM sleep (mean value = 18.9 +/- 10.9 mm Hg). The absence of the normal circadian BP dip seen during the nocturnal sleep period is considered as an indication of vascular risk. The REM sleep non dipping may play a role in this risk.

[Efficacy of exercise therapy to reduce cardiometabolic risk factors in overweight and obese children and adolescents: a systematic review]. / Wirksamkeit von Trainingsinterventionen zur Reduktion kardiometabolischer Risikofaktoren bei Kindern und Jugendlichen mit Übergewicht und Adipositas.

BACKGROUND AND OBJECTIVE: Excess weight in the younger population is associated with the various cardiovascular risk factors including hypertension, dyslipidemia and even metabolic syndrome early in life. Since these cardiometabolic profiles in children and adolescents track into adulthood they can give rise to the development of cardiovascular diseases and non-insulin-dependent diabetes. METHOD: A systematic literature search was performed in 4 electronic databases, Pubmed, PEDro, Cochrane Library und SPORTDiscus, looking for data on the efficacy of training programmes to improve cardiometabolic outcome parameters in overweight and obese children and adolescents. RESULTS: 12 randomized controlled trials were assessed eligible for inclusion. 9 of 12 trials documented improvements of at least one clinical or cardiometabolic marker in overweight children or adolescents upon completion of the training programme. CONCLUSION: Aerobic training programmes have the potential to effectively improve cardiovascular risk factors in overweight or obese children and juveniles. The evidence from previous studies is moderate. Further studies of high methodological quality are needed.

ECG signal analysis for the assessment of sleep-disordered breathing and sleep pattern.

The diagnosis of sleep-disordered breathing (SDB) usually relies on the analysis of complex polysomnographic measurements performed in specialized sleep centers. Automatic signal analysis is a promising approach to reduce the diagnostic effort. This paper addresses SDB and sleep assessment solely based on the analysis of a single-channel ECG recorded overnight by a set of signal analysis modules. The methodology of QRS detection, SDB analysis, calculation of ECG-derived respiration curves, and estimation of a sleep pattern is described in detail. SDB analysis detects specific cyclical variations of the heart rate by correlation analysis of a signal pattern and the heart rate curve. It was tested with 35 SDB-annotated ECGs from the Apnea-ECG Database, and achieved a diagnostic accuracy of 80.5%. To estimate sleep pattern, spectral parameters of the heart rate are used as stage classifiers. The reliability of the algorithm was tested with 18 ECGs extracted from visually scored polysomnographies of the SIESTA database; 57.7% of all 30 s epochs were correctly assigned by the algorithm. Although promising, these results underline the need for further testing in larger patient groups with different underlying diseases.

Clinical and haemodynamic effects of long-term treatment with torasemide in congestive heart failure.

The clinical and haemodynamic effects of 12 weeks of treatment with torasemide, 5 mg/day, were measured in 24 men aged 51-60 years with symptoms of mild, chronic, congestive heart failure. Clinical status was assessed by NYHA functional class and haemodynamic effects were measured at rest and during supine bicycle exercise at the beginning and end of the 12-week period of study. Torasemide was well tolerated and there was no significant change in any of the measured safety variables. Clinical status was improved in 16 of the 23 patients assessed after 12 weeks of treatment and none experienced symptomatic deterioration. Compared with pretreatment haemodynamic measurements, right atrial and pulmonary vascular pressures were significantly decreased both at rest and during exercise after torasemide. Systemic arterial pressure was reduced at rest, but there were no significant changes in cardiac output, heart rate, or systemic and pulmonary vascular resistances either at rest or during exercise, neither were there any significant changes in systemic arterial blood oxygen saturation, pulmonary arterial blood pH, gas tensions, or bicarbonate concentration either at rest or during exercise at 12 weeks. The results of these studies indicate that the clinical and haemodynamic benefits of torasemide are not subject to the development of tolerance during sustained treatment.

[Psychological aspects of sleep related disorders of respiratory control]. / Psychologische Aspekte schlafbezogener Atemregulationsstörungen.

An impaired ability to concentrate, loss of intellectual performance, and changes in personality are frequently-mentioned psychological symptoms of sleep apnoea. Apnea-associated disturbances of sleep structure as well as nocturnal cerebral hypoxia are possible causes. Twenty men and two women with an average age of 51.5 years underwent psychological testing. The average apnea index was 36 (range 11 to 92). The following psychodiagnostic procedures were used for screening; attention-strain test (d2) to measure short term concentration ability, numbers-connecting test (ZVT) for the evaluation of cognitive processing speed as an indication of intellectual performance, the Freiburg Personality Inventory FPI-R for assessing personality traits. As compared with the standard random sample of the d2, our patients' ability to concentrate over a period of five minutes does not seem to be impaired. Deficits in patients with sleep apnea are more likely to be found in the care of long-term concentration, especially in monotonous situations. The mean IQ score of our sample (93) is rather low as compared with the mean value of the age-matched sample (100). Patients with an Apnea index greater than 30 tended to have lower IQ-values (87.4) than those with less severe sleep apnea (97). Older patients had significantly lower age-corrected figures (87.2) than younger patients (98). Younger patients with high apnea activity (greater than median) had significantly (ANOVA: interaction alpha = 0.01) lower IQ scores (84.8) than younger patients with less severe sleep apnea (107). Sleep apnea seems to impair cognitive processing speed. Our sample turned out to be normal with respect to the twelve personality traits measured by means of the FPI-R.(ABSTRACT TRUNCATED AT 250 WORDS)

[Actigraphy: methodological limits for evaluation of sleep stages and sleep structure of healthy probands]. / Aktigraphie: Methodische Begrenzungen für die Beurteilung von Schlafstadien und Schlafstruktur gesunder Probanden.

UNLABELLED: Purpose of the investigation was to evaluate the differences of movement density during the sleep stages and waking. 22 diurnally active, healthy, male volunteers of mean age 30.7 (+/-Standard deviation +/- 3.3) years and a Body-Mass-Index 23.6 +/- 3.3 kg/m2 participated in the study. All subjects were recorded in the sleep lab via cardiorespiratory polysomnography and wrist actigraphy (Ambulatory Monitoring, Ardsley, USA) worn on the non-dominant hand, for two consecutive nights. The activity data, consisting of the number of zero crossings (NZC) were recorded in 1-minute periods. Sleep stages were scored visually according to standard criteria. EEG- and actigraphy data were converted to the same data format (European Feature Files). Attaching the actimetry data to the sleep stages was calculated mean NZC for every sleep stage and Wake. In spite of high differences in total individual NZC we observed that most NZC occurred during Wake. NREM 1 movement density was significantly higher in 19 recordings (86%) than in any other sleep stage. In 18 cases (82%) lowest movement density was found in NREM 3/4 with significant difference to all other sleep stages. Within 50% of the recordings were found decreasing activity in the following sequence of stages: Wake > NREM 1 > REM > NREM 2 > NREM 3/4 However, in all other cases there was a varying pattern of activity. CONCLUSION: Although there is some correlation between motor activity and sleep stages, the predictive value of actimetry data analysis in the assessment of sleep structure appeared to be limited mainly by individual movement density, especially during REM and NREM 2.

Ambulatory recording of sleep apnea using peripheral arterial tonometry.

Sleep related breathing disorders are common. A reliable diagnosis with relatively simple and portable methods is still needed. One approach is to make use of autonomous nervous system changes which accompany disordered breathing during sleep. The peripheral arterial tonometry (PAT) determines the peripheral arterial vascular tone using a plethysmographic method on the finger. The peripheral arterial tone is modulated by sympathetic activity, by peripheral blood pressure, and by the peripheral resistance of the vessels. We investigate a new ambulatory recording device which uses PAT, oximetry and actigraphy in order to detect sleep apnea. For this purpose we performed a comparative study on 21 patients referred to our sleep laboratory due to suspected sleep apnea. Of these 17 valid recordings were compared. The Watch-PAT was used in parallel with cardiorespiratory polysomnography and the validity was determined. The new system is able to detect apneas and hypopneas with a high reliability (r=0.89). It is very sensitive to arousals (r=0.77). Since arousal are not specific to sleep apnea the specificity of the new system could not be finally clarified in this study. We conclude that the new system is very well suited to perform control studies in patients with sleep apnea which are under therapy and require regular follow-up investigations to maintain a high CPAP compliance.

[Risk of accident due to hypersomnia: relevance for sleep medicine]. / Unfallrisiko durch Hypersomnien: Bedeutung für die Schlafmedizin.

Hypersomnia is increasingly recognized as a potential causal factor for accidents. Information of the general public about scientific knowledge on the area of fatigue and sleepiness is, as well as the recognition and treatment of disorders impairing vigilance, an important task for sleep medicine. Fulfilling this task will warrant an important contribution to increase road safety. Sleep related disordered breathing is an example that shows the sense and the need for a qualitatively good medical care of patients with sleep related disorders.

Risk of traffic accidents in patients with sleep-disordered breathing: reduction with nasal CPAP.

Sleepiness whilst driving constitutes a road safety risk. Sleep-related breathing disorders are the most frequent medical cause of daytime sleepiness, and untreated patients with this condition have been shown to be at a higher risk of having accidents while driving. This study addressed the question of the extent to which treatment of sleep-disordered breathing by nasal continuous positive airway pressure (nCPAP) is related to changes in patient's accident risk. Seventy eight male patients requiring treatment of sleep-related breathing disorders with nCPAP were enrolled in the study. The protocol included a questionnaire dealing with alertness-related problems while driving, an 80 min vigilance test, and the Multiple Sleep Latency Test. These baseline evaluations were repeated after 1 year of treatment with nCPAP. Fifty nine patients completed the study. The accident rate was significantly decreased from 0.8 per 100,000 km (untreated) to 0.15 per 100,000 km with nCPAP treatment. Variables that were considered to be likely to increase accident risk (sleeping spells, fatigue, vigilance test reaction time, daytime sleep latency) also improved with treatment. We conclude that treatment of sleep-disordered breathing by nasal continuous positive airway pressure is related to reduction in patient motor vehicle accident rates, probably due to the reversal of excessive daytime sleepiness.

Unattended continuous positive airway pressure titration. Clinical relevance and cardiorespiratory hazards of the method.

The high cost of in-laboratory sleep studies and the insufficiency of available nights in most sleep laboratories has prompted clinical trials in an attempt to find an effective and safe method for continuous positive airway pressure (CPAP) titration in the unsupervised home environment. Earlier publications focused on the effectiveness of this new method but did not indicate the potential hazard and the selection criteria of patients. We accomplished a prospective study to evaluate a machine-controlled CPAP titration method in an unselected group of 21 patients with obstructive sleep apnea (OSA) requiring CPAP therapy. Unattended CPAP titrations were completed in the sleep laboratory, followed by conventional CPAP titration night. The CPAP levels assessed through automatic titrations showed strong agreement with those from the control nights. Fifteen patients had no pathologic cardiorespiratory events during machine-controlled titration. Undesirable cardiorespiratory complications developed in six patients with underlying cardiorespiratory disorder. Two patients had to stop the procedure. Two patients needed a reset of the actual pressure to baseline because of central apneas and one patient because of high-grade arrhythmia. The machine-controlled CPAP titration enabled reliable assessment of an effective pressure and appeared to be safe in selected patients with OSA. However, because the method caused significant adverse effects in some patients, we recommend that unattended CPAP titration not be attempted in patients with underlying cardiorespiratory disease.

[Morbidity and mortality in sleep apnea and nocturnal bradyarrhythmia]. / Morbidität und Letalität bei Schlafapnoe und nächtlichen Bradyarrhythmien.

The as yet unanswered question, whether patients with sleep apnoea and apnoea-associated bradyarrhythmias have a higher morbidity and mortality rate, was retrospectively investigated in 132 men with sleep apnoea (apnoea index > 10/h). Sleep-associated bradycardic arrhythmias were recorded in 71 (mean age 50.1 years; group 1). For comparison served 61 men with sleep apnoea but no bradyarrhythmias (mean age 51.4 years; group 2), matched for age and weight. There was no significant difference between the two groups as to diagnosis and initial findings on ergometry, lung function tests and blood gas analysis. The apnoea index of 48.1 +/- 23.9/h in group 1 was significantly higher than that of 31.9 +/- 20.1/h in group 2 (P < 0.001). During a follow-up period of a mean of 41.1 (19-66) months, two patients in group 1 died (of myocardial infarction), while one died (of bronchial carcinoma) in group 2 (follow-up period of 29.6 [18-54] months). The two deaths in group 1 were in a subgroup of 16 patients who had declined treatment or had used it irregularly. There was no death among those who had been treated (n = 54), by nasal continuous positive airway pressure, operation or pacemaker implantation. However, no causal relationship could be established from these data between increased mortality rate and apnoea-associated arrhythmias.

[Pulmonary artery blood pressure and snoring]. / Pulmonalarterieller Blutdruck und Schnarchen.

Snoring is an extrathoracic inspiratory airway obstruction during sleep, accompanied by more or less intense noise. The inspiration volume being limited at the same time, this can produce additional blood gas changes. Epidemiological studies have shown an increased risk of myocardial infarction or cerebral ischaemia during night for snorers. Little is known, however, about acute effects of snoring on the haemodynamics of heart and circulation. The present study presents data of the pulmonary artery blood pressure during sleep-related upper airway obstruction. Pulmonary arterial pressure during sleep was examined with five patients via Swan-Ganz catheter. When an upper airway obstruction occurred, the inspiratory pulmonary arterial pressures rose in all the five patients. Two patients showed a clinically significant decrease in arterial oxygen saturation during snoring so that in these cases, a hypoxic vasoconstriction can be discussed as a possible cause. The other three patients did not produce significant decreases in oxygen saturation, so that in these cases mechanical factors (negative inspiratory intrathoracic pressure oscillations) should be regarded as the most probable cause for increases in the pulmonary arterial blood pressure.

[Risk of accidents in patients with nocturnal respiration disorders]. / Unfallgefahr von Patienten mit nächtlichen Atmungsstörungen.

Excessive daytime sleepiness is one of the main symptoms of sleep apnoea, which can, especially in monotonous situations, lead to real nodding off. Since driving a motor vehicle can also be monotonous, patients suffering from untreated sleep apnoea may be a possible traffic risk. Before undergoing a polysomnographic examination, 123 patients filled in a questionnaire inquiring about fatigue and sleepiness while driving a vehicle as well as accidents during the past three years. Five groups were formed according to severity of sleep apnoea. Right through these groups, the increase in heavy fatigue during driving (median) was significant: from "seldom" (AI less than 5) via "sometimes" to "often" (AI greater than or equal to 35). Occurrences of short periods of falling asleep (means) were practically not reported (0.02) by the group without sleep apnoea but increased considerably to 3.37 times per 1000 km for the group with an AI greater than or equal to 35. The frequency of accidents due to sleepiness rises significantly in concurrence with the seriousness of sleep apnoea. Besides, patients with an AI greater than or equal to 5 attribute 23 out of 28 accidents to sleepiness, whereas patients without sleep apnoea attribute all four accidents to other reasons (p = .0035). These findings emphasise the importance of an early diagnosis and effective therapy of sleep apnoea - which is available as nasal continuous positive airway pressure ventilation (nCPAP). Sleep medicine can thus not only help patients suffering from sleep apnoea but may also reduce the health risk of other traffic participants and be cost-saving.