Assiut University



HYPERLINK "" \h Egyptian Journal of Chest Diseases and Tuberculosis (2016) xxx, xxx–xxxThe Egyptian Society of Chest Diseases and TuberculosisEgyptian Journal of Chest Diseases and Tuberculosislocate/ejcdt H OSTED B Y ORIGINAL ARTICLERole of continuous positive airway pressure in patients with combined sleep apnea syndromewithout congestive heart failureShereen Farghaly 1,*, Alaa Thabet 2 Chest Department, Assiut University Hospital, Egypt Received 31 December 2015; accepted 16 March 2016KEYWORDSHeart failure; Sleep apnea; CPAP;Combined syndromeAbstract Continuous positive airway pressure (CPAP) is a standard treatment of moderate and severe obstructive sleep apnea syndrome. However, its effect in patients with coexisting obstructive and central apneas is controversial.Objectives: To determine the immediate response to CPAP in combined obstructive and central sleep apnea patients without heart failure.Methods: Thirty seven consecutive patients with moderate and severe coexisting obstructive and central apneas (combined group) were prospectively enrolled in this cross sectional analytic study. All patients underwent a full night-attended and a full night CPAP titration polysomnography. Titration was considered successful if AHI < 10 and the titration study included at least 15 min in REM stage.Results: On CPAP titration, the combined group showed signi?cant improvement in sleep and respiratory polysomnographic parameters. Mean AHI was reduced from 71.9 ± 30.3 to8.39 ± 5.15 (P = 0.000). Whereas CPAP signi?cantly reduced the central apnea index from12.8 ± 6.67 to 3.1 ± 2.86 (P = 0.000), the response to central events was variable (ranged from 20% to 100%). Overall results, 25 (67.6%) had successful titration with signi?cant better response in females than males to CPAP than males (88.9% vs. 60.7%, P = 0.019).Conclusion: CPAP can be effective in combined obstructive and central apnea patients without heart failure with consideration of individual variability. A trial of CPAP titration should be done in those patients. 2016 The Egyptian Society of Chest Diseases and Tuberculosis. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license ().* Corresponding author at: Chest Department, Assiut University Hospital, Zip Code: 71111, Egypt. Tel.: +20 01003085436. E-mail addresses: shereen_hssn@ (S. Farghaly), alaathabet35@ (A. Thabet).1 Has a role in design of study, analysis of results and discussion of results.2 Has a role in design of study, revision of the results and decision of ?nal publishing.Peer review under responsibility of The Egyptian Society of Chest Diseases and Tuberculosis. 2016 The Egyptian Society of Chest Diseases and Tuberculosis. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license ().Please cite this article in press as: S. Farghaly, A. Thabet, Role of continuous positive airway pressure in patients with combined sleep apnea syndrome without con- gestive heart failure, Egypt. J. Chest Dis. Tuberc. (2016), . Farghaly, A. ThabetIntroductionSleep related breathing disorders (SRBD) have been recently classi?ed into obstructive sleep apnea syndrome (OSAS), the central sleep apnea syndrome (CSAS) and Cheyne–Stokes respiration (CSR) [1]. Due to overlap of mechanisms of upper airway obstruction and ventilatory instability causing these disturbances, one patient could present with combination of obstructive and central events in one night. This condition is commonly present in patients with congestive heart failure but can interestingly occur without heart failure [2].Continuous positive airway pressure (CPAP) acts as a pneumatic splint to the upper airway during sleep and corrects the obstruction. It therefore can improve oxygenation and sleep architecture [3]. While the treatment of obstructive sleep apnea syndrome is generally straight forward and successful with CPAP therapy, [4] treatment of sleep apnea with predom- inantly mixed apneas, CSA and CSR is not universally agreed upon. CSA occurring with episodes of obstructive or mixed apnea may respond to nasal CPAP therapy [5–7]. One possible explanation is that CPAP increases lung volume and oxygen stores and alleviates hypoxia. Also, it prevents the occurrence of upper airway narrowing or occlusion during central apnea resulting in decreasing ventilatory overshoot and stabilization of ventilation [8]. Other reports have demonstrated either no change or a worsening of apnea/hypopnea index (AHI) during acute administration of nasal CPAP [9,10]. Depending on these results, a trial of CPAP may be effective in treatment of patients with coexisting obstructive and central sleep apnea.Aim of the studyTo determine the immediate effect of CPAP on elimination of apneas, improvement of oxygenation and sleep architecture in combined obstructive and central sleep apnea patients without heart failure.Patients and methodsPatient selection Inclusion criteriaWe included adult patients with coexisting obstructive and central sleep disordered breathing (combined group) (diag- nosed by polysomnography as total AHI P 15 and central AHI P 5 and the central AHI < 50% of total AHI).To be eligible for enrollment in the study, patients should undergo full night diagnostic and full night CPAP titration polysomnographic study.Exclusion criteriaPatients with pure OSAS.Patients associated with other pulmonary diseases as COPD, asthma, interstitial lung disease, bronchiectasis etc.Patients with left-sided heart failure.Patients who developed claustrophobia or excessive mask leak (leak > 0.04 L/s > 20% of total sleep time) during CPAP titration.Patients with split night sleep study.Study designThis cross-sectional analytic study was carried at the sleep lab- oratory of the Chest Department of Assiut University Hospi- tal. An informed written consent was obtained from all the patients enrolled in the study. The study was approved by the Faculty of Medicine Ethics Committee, Assiut University. Over a period of one and half years, we assessed patients coming for full night polysomnography. Patients with moder- ate to severe combined sleep apnea were prospectively enrolled in the study and prepared for second full night attended CPAP titration sleep study.Clinical assessmentClinical history suggestive of sleep apnea syndrome was taken from the patients and their partner with a history of associated co-morbid disease as diabetes mellitus, hypertension or IHD. Physical assessment including anthropometric measurement of height, weight and body-mass index (BMI) and reviewing of patients pulmonary function tests, previous chest X-ray and echocardiography was carried out.PolysomnographyAll patients underwent full over-night attended diagnostic as well as therapeutic (on CPAP) polysomnography (Sleep Lab Pro, Jaeger, VIASYS Healthcare Hoechberg, Germany). On both the two nights, the polysomnogram systematically monitored electroencephalogram (EEG) (C3-A2, C4-A1), electro-oculogram (EOG), electromyogram of the chin (EMG), electrocardiogram (EKG), nasal and oral air?ow (using oronasal ?ow thermistor in the diagnostic study and a piezoelectric pressure sensor to record mask pressure in the therapeutic study), thoracic and abdominal effort (using piezoelectric belts), limb movements (by means of EMG on anterior tibialis muscle), pulse oximetry, body position (recorded by a position sensor) and snoring sound level (by means of a microphone placed externally to the trachea).CPAP titrationCPAP therapy was introduced with full night attended polysomnography within 3 weeks after the diagnostic study. All patients received CPAP via an oronasal mask which was selected individually. The auto mode of CPAP device (Resmed, Autoset spiritTM) with a pressure range of 4–20 cm H2O was used for automatic titration. It automatically increased or decreased mask pressure in response to snoring or the presence of apneas or hypopneas, thus acting to com- pletely restore airway patency. It detected degree of obstruc- tion by reviewing the shape of the inspiratory ?ow curve on a breath-by-breath basis. A normal unobstructed breath gives a smooth rounded curve shape, but, as the upper airway nar- rows, ?attening of the curve occurs, altering the shape. The degree of ?attening determines the response of the device [11]. Preparation of the patients was done by a technician who supervised the study, and adjusted the mask ?t to com- pensate for leak and patient discomfort.Polysomnography scoringThe polysomnograms were scored automatically and revised manually according to American academy of sleep medicine [12]. Apnea was de?ned as a complete cessation of air?ow for more than 10 s. Obstructive apnea was an apnea with pre- served respiratory effort. Central apnea is an apnea with absent respiratory effort. Hypopnea required an event of at least 10 s duration in association with a P30% drop in the baseline amplitude and a P4% desaturation from the baseline saturation. The AHI was calculated as the number of apnea and hypopnea events per hour of sleep. Desaturation was detected by drop of at least 4% below baseline. An arousal was de?ned as an abrupt change in the EEG frequency to alpha, theta, or faster frequency in non-rapid eye movement (NREM) sleep with an increase in submental EMG as well in rapid eye movement (REM) lasting at least 3 s [13].After manual scoring of the different previous variables, a polysomnographic report was printed including data of sleep [total seep time (TST), sleep ef?ciency, sleep stages%], respira- tory [total, NREM and REM AHI, obstructive and central events and oxygen indices (desaturation index (DI), average oxygen level, minimum oxygen level, time spent below 90% (T90)] and cardiovascular [slowest and fastest heart rate] parameters. In the report of the second night, data about dif- ferent CPAP pressures applied during the study were detected. Titration was considered successful if overall results showed AHI < 5 and the study included at least 15 min in REM stage.Statistical analysisStatistical Package for the Social Sciences (SPSS-version 16) software was used for analysis of results. Results in this study were presented in mean ± standard deviation or number and percentage. The qualitative data were compared between the successful and non successful group using chi-square test. Paired sample student t-test was used to analyze quantitative polysomnographic data on CPAP compared to baseline. The difference was considered signi?cant when P < 0.05.ResultsWe included 37 with coexisting obstructive and central sleep apnea (combined group) for analysis. We excluded 62 patients with pure OSAS, 30 patients with associated pulmonary dis- eases and 9 patients with excessive leak during CPAP titration. The combined group was 67.6% male with a mean age of51.22 ± 8.9. They were obese with mean BMI 40.21± 8.022. The demographic data are shown in Table 1.On CPAP titration, the combined group showed a signi?- cant improvement in most polysomnographic variables. Sleep ef?ciency was signi?cantly increased. Light sleep (stage 1 and stage 2) % of TST was signi?cantly decreased with a signi?- cant increase in % of both of deep (i.e. stage 3) and REM sleep. Furthermore, CPAP signi?cantly reduced all apneas events and improved oxygenation. Mean AHI was reduced from 71.9 ± 30.3 to 8.39 ± 5.15 (P = 0.000). Whereas CPAPsigni?cantly reduced the obstructive apnea index (OAI) from 29.50 ± 22.30 to 4.86 ± 3.6 (P = 0.000) (Fig. 1) and the cen-tral apnea index from 12.8 ± 6.67 to 3.1 ± 2.86 (P = 0.000), the response to central events was variable (ranged fromTable 1 Demographic data of the study group.Variable(N = 37)Age (mean ± SD)51.22 ± 8.9Gender (%)Male28 (75.6%)Female9 (24.3%)Smoking habit (%)Smoker16 (43.2%)BMI (mean ± SD)40.21 ± 8.022Comorbidities (%)Hypertension23 (62.2%)Diabetes mellitus14 (37.8%)Ischemic heart disease14 (37.8%)Data expressed as number (%) or mean ± SD (standard deviation).BMI, body mass index.Figure 1 The response of obstructive apnea index (OAI) to CPAP in patients with combined sleep apnea syndrome. CPAP signi?cantly reduced the OAI from 29.50 ± 22.30 to 4.86 ± 3.6 (P = 0.000). The degree of response varies from 60% to 100%.20% to 100%) (Fig. 2). Average (84.36 ± 6.76 vs. 90.37± 6.27, P = 0.000) and minimum (58.9 ± 17.5 vs. 79.45± 9.54, P = 0.000) oxygen saturation were signi?cantly increased with a signi?cant reduction in T90 (60.3 ± 47.9 vs.7.75 ± 11.9, P = 0.000). Arousal index was signi?cantly decreased from 33.98 ± 9.66 to 8.5 ± 6.16 (P = 0.000). Also CPAP signi?cantly increased the slowest heart rate in the titra- tion night compared to the diagnostic study (49.5 ± 9.01 vs. 37.08 ± 13.8, P = 0.000) (Table 2).Overall results, 25 (67.6%) of the combined group had suc- cessful titration with AHI < 5. Among the combined group, Female patients showed better response to CPAP than males (88.9% vs. 60.7%, P = 0.019). Patients with successful initial CPAP titration had a signi?cantly higher baseline total AHI, CAI, REM AHI than those who failed titration (Table 3).DiscussionObstructive sleep apnea syndrome is a common sleep related breathing disorder [14]. Many patients with OSAS show at4S. Farghaly, A. ThabetFigure 2 The response of central apnea index (CAI) to CPAP in patients with combined sleep apnea syndrome. CPAP signi?cantly reduced the CAI from 12.8 ± 6.67 to 3.1 ± 2.86 (P = 0.000). Note (arrows) the wide variability of response of CAI (varies from 20% to 100%).Table 2 Polysomnographic parameters of the combined group (n = 37).TST, total sleep time; AHI, apnea hypopnea index; OAI, obstructive apnea index; CAI, central apnea index; REM, rapid eye movement;NREM, non-rapid eye movement; DI, desaturation index; T90, time spent below 90% in minutes.* Signi?cant.least a minor proportion of coexisting central disturbances [15]. That may be likely due to the overlapping of mechanisms causing these disturbances. Obstructive apneas, probably through intermittent hypoxia, can increase the ventilatory response to subsequent apneas and produce central apneas [16]. Stimulation of the mechanoreceptors of the upper airway when by obstructive efforts may favor the occurrence of cen- tral events through their action on the central drive to breathe [17]. Ventilatory instability (an important pathophysiological disturbance found in obstructive apnea patients) which leadsto pharyngeal obstruction may also increase the ventilatory response to arousal and drives Pa CO2 below the apnea threshold during subsequent sleep causing central apnea [18]. In heart failure, there is evidence for an overnight shift in predominance of obstructive apneas to central apneas [19]. Although CPAP was considered the standard treatment of OSAS, there was little evidence in its role in patients with coexisting central and obstructive events.Thus we carried out this study to evaluate the immediate effect of CPAP on patients with coexisting obstructive and central sleep apnea without congestive heart failure. On its effect on sleep variables, similar to previous studies [20–22] carried out on OSAS patients, it signi?cantly improved all sleep variables. Light sleep (stage 1 and stage 2) (P < 0.001) percent was signi?cantly decreased with a signi?cant increase in both deep sleep (i.e. stage 3) and REM stage as a % of total sleep time (P < 0.001). On the other hand, Lofaso and coworkers [23] found an increase in slow-wave (71 ± 86 vs. 102 ± 149 min) but not REM sleep on APAP and Randerath et al. [24] found an increase in REM sleep but no change in slow-wave sleep compared to baseline. In heart failure patients with coexisting obstructive and Cheyne stoke breathing, Randerath et al. [25] reported no immediate improvement on sleep quality on CPAP but only after 3 months of treatment with a signi?cant decrease in stage 1 and 2 (P < 0.01) and increase in stage 3 (P < 0.01).The ?ndings that CPAP signi?cantly reduced all apnea events, arousal and improved oxygenation in our combined group were comparable with previous studies. In patients with congestive heart failure, Kasai et al. [26] and Randerath et al. [25] noted that a signi?cant reduction of AHI is in the titrationVariableBaseline (n = 37)sCPAP (n = 37)P-valueMean ± SDMean ± SDSleep parametersTST (h)4.56 ± 0.074.58 ± 0.940.345Sleep efficiency (%)88.39 ± 4.991.38 ± 4.90.016*Stage 1 (%)26.4 ± 12.918.5 ± 21.850.001*Stage 2 (%)50.6 ± 19.548.66 ± 18.760.024*Stage 3 (%)8.14 ± 13.213.12 ± 12.70.014*REM (%)9.11 ± 15.813.11 ± 12.850.015*Respiratory parametersAHI (event/h)71.9 ± 30.38.39 ± 5.150.000*NREM AHI72.7 ± 30.77.45 ± 6.940.000*REM AHI50.36 ± 29.86.34 ± 7.340.000*OAI29.50 ± 22.304.86 ± 3.60.000*Hypopnea index12.5 ± 10.41.1 ± 0.930.000*CAI12.8 ± 6.673.1 ± 2.860.000*DI (event/h)54.48 ± 27.197.08 ± 4.80.000*Average O2 (%) Minimum O2 (%) T90 (min)84.36 ± 6.7658.9 ± 17.560.3 ± 47.990.37 ± 6.2779.45 ± 9.547.75 ± 11.90.000*0.000*0.000*Arousal index (event/h)33.98 ± 9.668.5 ± 6.160.000*Cardiovascular parametersFastest heart rate101.1 ± 19.6103.1 ± 17.270.362Slowest heart rate37.08 ± 13.849.5 ± 9.010.000*VariableSuccessful titrationUnsuccessful titrationP-value(N = 25)(N = 12)Gender % Male17 (68.2%)11 (39.3%)0.019*Female8 (88.9%)1 (8.3%)BMI (mean ± SD)41.34 ± 7.8643.12 ± 8.320.509ESS (mean ± SD)Baseline AHI (mean ± SD) Baseline CAI (mean ± SD)10.21 ± 2.662.01 ± 22.569.9 ± 2.4511.72 ± 2.992.9 ± 22.215 ± 8.760.1050.000*0.020*Baseline NREM AHI (mean ± SD) Baseline REM AHI (mean ± SD)73.48 ± 23.124.8 ± 14.7482.9 ± 23.981.48 ± 4.60.0750.000*Table 3 Potential predictors of successful initial CPAP titration in the combined group (n = 37).Data expressed as number (%) or mean ± SD (standard deviation).ESS, Epworth sleepiness scale; BMI, body mass index; AHI, apnea hypopnea index; CAI, central apnea index; NREM, non-rapid eye movement; REM, rapid eye movement.* Signi?cant.study. In randomized short term trials [27–29] in which noctur- nal CPAP was applied for one night, despite a signi?cant improvement in total AHI and oxygen saturation, central AHI was reduced on CPAP by about 50%. The better results reported in this study (reduction of central AHI by 80%) might be due to that the previous studies evaluate patients with predominantly central apnea with exclusion of those with obstructive AHI > 10/h. Furthermore, all hypopneas were scored as obstructive events as we could not differentiate between central and obstructive hypopneas and thus the possi- bility of under estimation of central events in our cases. Interestingly, as in previous studies, [28,30] we observed that a reduction of central events was variable (varies from 20% to 100%). It was supposed that at the time CPAP caused immediate and complete suppression of obstructive sleep apnea in patients with [31] and without [32] CHF, its effects on CSA were gradual and time dependent. Studies applying gradual CPAP titration protocol and treatment for a period of 2–12 weeks showed a further improvement of central events by 50–65% than the ?rst night [33,34,28]. As it was postulated that that breathing stability rather than upper airway collapsi- bility distinguishes patients with a combination of obstructive and central events from those with pure OSA, those patients were expected to take a period to adapt to CPAP [35]. It had been demonstrated that treatment of CSA with CPAP for a period of 2 weeks or longer stabilized the ventilatory control system by increasing nocturnal transcutaneous PCO2, [6] total body oxygen stores [36] and reducing ventilatory drive [34]. We hypothesized that central apneas induced by obstructive events following arousals or induced by negative mechanoreceptor stimulation could disappear after correction of obstruction by CPAP. The different mechanisms of the pathogenesis of patients with combined obstructive and central events led to heterogeneous response to CPAP. Those patients with patho- genesis other than ventilatory instability could show immedi- ate improvement on CPAP.Interestingly, female patients in our study showed a better response to CPAP than males. Generally, men had less stable sleep architecture with frequent arousals and shorter slow wave than women which might predispose them to respiratory control system instability [37] and thus the need for time toshow optimum response to CPAP. Furthermore the small number of females in our study could make this difference.A problem in sleep apnea studies is the exact differentiation between obstructive and central hypopneas. Measurement of esophageal pressure is the gold standard approach to detect respiratory effort but is dif?cult to be applied in that study. Besides, limitations of this study included the small number of included patients but that was due to the limited inclusion criteria in that study to ?nd this group of patients and also the absence of a de?nite cause of the presence of central events in those OSAS patients.In conclusion, CPAP can be effective in combined obstruc- tive and central apnea patients without heart failure with consideration of individual variability. So a trial of CPAP titration should be considered in every patient with combined sleep apnea syndrome without heart failure. Further studies are recommended to evaluate the long term effect of CPAP in those patients.Conflict of interestAll authors declare there is absence of con?ict of interest in this study. There is also no ?nancial support by any organization.AcknowledgmentsThe authors wish to express their thanks to sleep technicians in the Chest Department, Assiut University Hospital for their great help in arranging appointments and educating patients about the sleep study.References[1] Sleep-related breathing disorders in adults: recommendations for syndrome de?nition and measurement techniques in clinical research. The report of an American Academy of Sleep Medicine Task Force, Sleep 22 (1999) 667–689.[2] W.J. Randerath, W. Galetke, S. Stieglitz, C. Laumanns, T. Schafer, Adaptive servo-ventilation in patients with coexisting6S. Farghaly, A. Thabetobstructive sleep apnoea/hypopnoea and Cheyne–Stokes respiration, Sleep Med. 9 (2008) 823–830.[3] S.R. Patel, D.P. White, A. Malhotra, M.L. Stanchina, N.T. 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