Thomas Ploch

Effect of Nasal Continuous Positive Airway Pressure Treatment on Blood Pressure in Patients With Obstructive Sleep Apnea

Background—There is increasing evidence that obstructive sleep apnea (OSA) is an independent risk factor for arterial hypertension. Because there are no controlled studies showing a substantial effect of nasal continuous positive airway pressure (nCPAP) therapy on hypertension in OSA, the impact of treatment on cardiovascular sequelae has been questioned altogether. Therefore, we studied the effect of nCPAP on arterial hypertension in patients with OSA. Methods and Results—Sixty consecutive patients with moderate to severe OSA were randomly assigned to either effective or subtherapeutic nCPAP for 9 weeks on average. Nocturnal polysomnography and continuous noninvasive blood pressure recording for 19 hours was performed before and with treatment. Thirty two patients, 16 in each group, completed the study. Apneas and hypopneas were reduced by ≈95% and 50% in the therapeutic and subtherapeutic groups, respectively. Mean arterial blood pressure decreased by 9.9±11.4 mm Hg with effective nCPAP treatment, whereas no relevant change occurred with subtherapeutic nCPAP (P =0.01). Mean, diastolic, and systolic blood pressures all decreased significantly by ≈10 mm Hg, both at night and during the day. Conclusions—Effective nCPAP treatment in patients with moderate to severe OSA leads to a substantial reduction in both day and night arterial blood pressure. The fact that a 50% reduction in the apnea-hypopnea index did not result in a decrease in blood pressure emphasizes the importance of highly effective treatment. The drop in mean blood pressure by 10 mm Hg would be predicted to reduce coronary heart disease event risk by 37% and stroke risk by 56%.

Quantification of tonic and phasic muscle activity in REM sleep behavior disorder.

Summary: REM sleep behavior disorder (RBD) is characterized by excessive tone of the chin muscle and limb movement during sleep. In the past, quantification of increased muscle tone in REM sleep has been performed visually, using no stringent criteria. The aim of this study was to develop an automatic analysis, allowing the quantification of muscle activity and its amplitude for all sleep stages, with a focus on REM sleep in patients with RBD. Forty-eight patients (27 male, 21 female) with RBD were included in the analysis. Twenty-one had idiopathic RBD; 28 had narcolepsy plus RBD. Twenty-five patients without confirmed sleep disorder served as control subjects. The amplitude of the EMG was generated from the difference of the upper and lower envelope of the mentalis muscle recordings. By smoothing the amplitude curve, a threshold curve was defined. Any muscle activity beyond the threshold curve was defined as motor activity. The means of the motor activity per second were summarized statistically and calculated for each sleep stage. Due to variable distribution of REM sleep, the latter was assigned to respective quartiles of the recorded night. Muscle activity was defined according to a histogram as short-lasting (<0.5 second) and long-lasting (>0.5 second) activity. No difference in the distribution of REM sleep/quartile and mean muscle tone throughout the sleep cycle could be found within the RBD groups and control subjects. Muscle activity was in the range of 200 ms. No clusters or regular distribution of muscle activity were found. Long muscle activity in the group with manifest clinical RBD was significantly higher than in control subjects, whereas it was nonsignificantly higher in subclinical RBD. The correlation between the frequency of long muscle activity in REM sleep and age was highly significant only for patients with idiopathic RBD. Automatic analysis of muscle activity in sleep is a reliable, easy method that may easily be used in the evaluation for REM sleep behavior disorder, creating indices of muscle activity similar to the indices for sleep apnea or PLMS. Together with the overt behavior, the analyses provides an important tool to get a deeper insight into the pathophysiology of RBD. Long movements appear to represent the motor disinhibition in REM sleep more distinct than short movements. The positive correlation of age and increased motor activity in REM sleep in idiopathic RBD highlights the idea of age dependant motor disinhibition as a continuum of a neurodegenerative disorder, which in narcolepsy patients with RBD only seems to happen as a single temporal event at onset of the disorder.

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 30xa0s 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.

Detection of sleep disordered breathing by automated ECG analysis

Sleep related breathing disorders are a highly prevalent disease associated with increased risk of cardiovascular complications like chronic arterial hypertension, myocardial infarction or stroke. Gold standard diagnostics (polysomnography) are complex and expensive; the need for simplified diagnostics is therefore obvious. As the ECG can be easily conducted during the night, the detection of sleep related breathing disorders by ECG analysis provides an easy and cheap approach. Using a combination of well known biosignals processing algorithms, we trained the algorithm on 35 pre-scored overnight recordings. We then applied the algorithm on 35 control recordings, achieving a diagnostic accuracy of 77%. We believe that with further improvements in ECG analysis this algorithm can be used for screening diagnostics of obstructive sleep apnea.

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 specifity 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.

CPAP im Rettungsdienst bei vermutetem kardiogenen Lungenödem

ZusammenfassungDas akute kardiogene Lungenödem ist einer der Hauptgründe für die Hospitalisierung von Patienten. Die Mortalität ist hoch, und viele Patienten benötigen eine Beatmung. Eine endotracheale Intubation jedoch hat – gerade in der präklinischen Situation – spezifische Komplikationen und birgt Risiken für den Patienten. Systematische Untersuchungen legen nah, dass die „continuous positive airway pressure“ (CPAP) -Therapie die Notwendigkeit der Beatmung und auch die Mortalität bei Patienten mit kardiogenem Lungenödem reduziert. Dennoch wird die Therapie präklinisch bisher nur selten eingesetzt.Wir therapierten insgesamt 108xa0Patienten mit vermutetem kardiogenen Lungenödem im Rahmen einer Beobachtungsstudie mit einem einfachen „flow-CPAP“-System (Fa. Vygon, Aachen) im Rettungswagen. Sowohl die Sauerstoffsättigung (von 82% auf 95%) als auch die Atemfrequenz (von 29/min auf 21/min) besserten sich hochsignifikant. Nur 8xa0Patienten (7,4%) mussten intubiert werden. Es wurden keine relevanten Komplikationen beobachtet. Diese Ergebnisse sprechen dafür, dass eine CPAP-Therapie sicher und erfolgreich auch in der präklinischen Notfallmedizin genutzt werden kann.AbstractAcute cardiogenic pulmonary edema (ACPE) is a common medical emergency and a leading cause for hospitalization. Mortality from ACPE is high and patients often require mechanical ventilation. Endotracheal intubation, especially in a prehospital setting, has specific associated complications which constitute risks for the patient. Continuous positive airway pressure (CPAP) has proved to be beneficial in certain cases of respiratory failure and is a widely accepted therapy in patients with pulmonary edema. Systematic reviews have suggested a reduced need for mechanical ventilation and reduced mortality in patients with ACPE treated with CPAP.We conducted a prospective one arm open study by treating 108xa0patients with suspected acute cardiogenic edema in the ambulance with a simple flow CPAP system (Vygon, Aachen, Germany). Saturation improved significantly from 82% to 95% with CPAP therapy and breathing frequency from 29/min to 21/min. Only 8xa0patients (7.4%) had to be intubated. No major complications occurred. The results of the study indicate that CPAP can be safely used in prehospital emergency medicine in patients with suspected acute cardiogenic edema.

C-Flex® Technology: Effects on Breathing Parameters and Inspiratory Flow Limitation

Background: Expiratory pressure relief continuous positive airway pressure (pressure relief CPAP, C-Flex®) is known to be as effective in the treatment of obstructive sleep apnea (OSA) as conventional CPAP while improving overall patients’ adherence. However, the effects of C-Flex on ventilation during sleep have not been studied yet. Objective: This study investigates the effects of pressure relief CPAP on respiratory parameters and possible inspiratory flow limitation with increased difference between inspiratory and expiratory pressure compared with conventional CPAP. Methods: In total, 24 patients were investigated both during conventional CPAP and during three C-Flex pressure relief settings in randomized order during rapid-eye-movement (REM) and non-REM (NREM) sleep. Airflow was monitored with a pneumotachograph; inspiratory flow limitation was assessed by analyzing airflow and esophageal pressure swings. Results: Using higher C-Flex gains, expiratory time decreased in favor of the inspiratory duty cycle while there was no significant change in tidal volume. Analysis of inspiratory flow limitation showed no significant difference between conventional CPAP and the C-Flex gains studied. Conclusions: The increase in the inspiratory duty cycle with C-Flex might either indicate an increase in the work of breathing or a decrease in the work of breathing due to a lower peak end-expiratory pressure and consecutive alleviation of passive expiration. Both treatments appeared equivalent regarding the occurrence of inspiratory flow limitation.

Work of Breathing in Fixed and Pressure Relief Continuous Positive Airway Pressure (C-Flex™): A post hoc Analysis

Background: Expiratory pressure relief continuous positive airway pressure (pressure relief CPAP; C-Flex™) causes increases in inspiratory duty cycle and shortening of expiratory time. It has been suggested that these changes are caused by an increase in work of breathing. Objectives: We studied the effects of C-Flex on work of breathing and intrinsic positive end-expiratory pressure as compared to fixed CPAP. Methods: Work of breathing was analyzed in 24 patients with obstructive sleep apnea during treatment with fixed CPAP and C-Flex with 3 different pressure relief settings in a randomized order during rapid-eye-movement (REM) and non-REM sleep. Work of breathing was assessed on a breath-by-breath basis using a piezoelectric esophageal pressure catheter and a pneumotachograph for measuring airflow. Results: We found there was no increase in inspiratory work of breathing observed using C-Flex compared to fixed CPAP. Instead, we found a linear decrease in inspiratory work of breathing with increasing pressure relief, with a mean difference of 1.22 J/min between CPAP and maximum pressure release (C-Flex 3; 90% of the value with nasal CPAP); however, the decrease was not statistically significant. The decrease in inspiratory work of breathing associated with C-Flex has a significant inverse correlation with BMI. Conclusions: The C-Flex technology does not change work of breathing but shows a tendency towards a reduction of inspiratory work of breathing in patients with a lower BMI using higher C-Flex. The effect is probably caused by diminishing airway resistance generated by the positive end-expiratory pressure. Our findings may lead to additional fields of application of the C-Flex technology, such as chronic obstructive pulmonary disease or muscular dystrophy.

Inspiratory flow limitation: Comparison of the C-flex system versus conventional therapy—A pilot study@@@Inspiratorische Flusslimitationen: Vergleich des C-Flex-Systems gegen eine konventionelle CPAP-Therapie-eine Pilotstudie

SummaryQuestion of the studyCompliance with nasal continuous positive airway pressure (nCPAP) treatment may be reduced due to difficulties when exhaling against a positive pressure. A recently introduced CPAP system therefore lowers the expiratory pressure proportional to the patients airflow. To evaluate the theoretical concern that this might induce, flow limitations during inspiration, we measured the occurrence of flow limitation during sleep.Patients and methodsEight subjects with treated obstructive sleep apnoea were studied with polysomnography including respiratory flow and oesophageal pressure measurement. Conventional CPAP and three settings of the new system were applied in a randomised order during both NREM and REM sleep. Two approaches for measuring inspiratory flow limitation were used: oesophageal pressure and respiratory resistance.ResultsUsing the oesophageal pressure criterion, 3.5% of breaths during CPAP mode were flow limited as compared to 1.4% during the new mode. Flow limitations using the novel criterion of respiratory resistance, we counted 13.6% of flow-limited breaths during CPAP mode and 10.1% during the new mode. Equivalence testing confirmed equivalence between the novel system and CPAP.ConclusionsThe results confirm that there is no increase in the number of flow limitations during the new mode as compared to CPAP.ZusammenfassungFragestellungManche Patienten klagen darüber, dass es für sie problematisch ist, gegen einen kontinuierlichen positiven Druck bei der CPAP-Therapie auszuatmen. Möglicherweise reduziert diese Problematik die Compliance der Patienten. Ein kürzlich eingeführtes CPAP-System senkt während der Exspiration den Druck proportional zum vom Patienten generierten Atemfluss ab. Ein Kritikpunkt dieser exspiratorischen Druckabsenkung ist, dass sie eventuell inspiratorische Flusslimitationen induzieren kann. Um diesen Aspekt zu klären, untersuchten wir das Auftreten von inspiratorischen Flusslimitationen während des Schlafs.Patienten und MethodikAn dieser Studie nahmen 8 Patienten mit mittels CPAP-Therapie behandelten schlafbezogenen Atmungsstörungen teil. Alle 8 Patienten unterzogen wir einer kompletten Polysomnographie inklusive inspiratorischer Flussmessung und Ösophagusdruckmessung. Eine konventionelle CPAP-Therapie und alle 3 Modi der neuen Therapie mit exspiratorischer Druckabsenkung wurden in randomisierter Reihenfolge während NREM und REM-Schlaf appliziert. Zur Erfassung von inspiratorischen, Flusslimitationen wurden 2 verschiedene Verfahren genutzt: der Ösophagusdruck und die Messung der respiratorischen Resistance.ErgebnisseMit dem Ösophagusdruckkriterium wurden 3,5% der Atemzüge unter konventioneller CPAP-Therapie und 1,4% unter Therapie mit exspiratorischer Druckabsenkung als flusslimitiert gewertet. Sowohl im NREM- als auch im REM-Schlaf war die Zahl der Flusslimitationen unter Therapie mit exspiratorischer Druckabsenkung signifikant reduziert. Erfasst mit der Methode der respiratorischen Resistance war der Anteil flusslimitierter Atemzüge höher: 13,6% während konventioneller CPAP-Therapie und 10,1% während der Therapie mit exspiratorischer Druckabsenkung. Die Äquivalenztestung bestätigte Äquivalenz zwischen der Therepie mit exspiratorischer Druckabsenkung und der konventionellen CPAP-Therapie.SchlussfolgerungDiese Ergebnisse zeigen, dass eine exspiratorische Druckabsenkung im getesteten System nicht zum Auftreten zusätzlicher inspiratorischer Flusslimiationen führt.

P478 Quantification of daytime sleepiness in young healthy subjects during a reaction time test (VIGIMAR) and Karolinska drowsiness test (KDT)

P477 Obstructive sleep apnea syndrome – Patient perceptions of their life situation before initiation of CPAP treatment Anders Brostrom , Peter Johansson , Anna Stromberg , Jan Albers , Jan Wiberg , Jan Martensson , Eva Svanborg 2 1 Department of Medicine and Care, Linkoping University, Linkoping, Sweden 2 Department of Neuroscience and Locomotion, Faculty of Health Sciences, LinkopingUniversity, Linkoping, Sweden 3 Department of Cardiology, Linkoping University Hospital, Linkoping, Sweden 4 Department of Internal Medicine, County Hospital Ryhov, Jonkoping, Sweden 5 Development Unit for Primary Health Care, Qulturum, Jonkoping, Sweden 6 Department of Nursing Science, School of Health Sciences, Jonkoping, Sweden