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0Egyptian Journal of Chest Diseases and Tuberculosis (2016) 65, 251-257
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The Egyptian Society of Chest Diseases and Tuberculosis
Egyptian Journal of Chest Diseases and Tuberculosis
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ORIGINAL ARTICLE
Efficacy of split night CPAP titration in moderate c^Ma*
and severe obstructive sleep apnea syndrome patients
Shereen Farghaly, Lamiaa H. Shaaban *
Chest Department, Assiut University, Egypt
Received 24 July 2015; accepted 31 August 2015 Available online 26 September 2015
KEYWORDS
CPAP titration; Split night; OSAS
Abstract Background: Split-night polysomnography was introduced to obtain diagnosis and determine an effective CPAP on a single night that would be convenient and cost effective.
Aim of the study: To evaluate the efficacy of split night CPAP titration in comparison with conventional full night titration in patients with moderate and severe OSAS.
Patients and methods: Matched patients for age, sex, body mass index and disease severity were enrolled in the study and classified into two groups either split night or full night group.
Results: Sixty matched patients in each group (full night and split night group) were included in the study. Regarding sleep parameters, sleep efficiency (75.9 ± 15.7 vs. 81.5 ± 10.5, p = 0.024) was significantly shorter, stage 1% was significantly higher (22.3 ± 14 vs. 17.9 ± 15.8, p = 0.013) and REM % (23.9 ± 18.7 vs. 31.3 ± 14.8, p = 0.019) was significantly lower during split night CPAP titration compared to full night titration study. Unsuccessful CPAP titration was significantly higher in split night group than the full night group (30 (50%) vs. 16 (35.5%), p = 0.025). Apnea hypopnea index >36.4 during diagnostic part and total sleep time at least 2.45 h during CPAP part of split night titration were identified as the optimum cut off for successful titration with 73.5% sensitivity, 43.3% specificity and 74% sensitivity, 70% specificity respectively.
Conclusion: Split night sleep study is more commonly associated with unsuccessful CPAP titration than full night titration but successful titration could be obtained during split night titration in patients with severe AHI >36.5 event/h.
© 2015 The Authors. Production and hosting by Elsevier B.V. on behalf of The Egyptian Society of Chest Diseases and Tuberculosis. This is an open access article under the CC BY-NC-ND license (http://
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Introduction
* Corresponding author.
Peer review under responsibility of The Egyptian Society of Chest Diseases and Tuberculosis.
Obstructive sleep apnea syndrome (OSAS) is the most common type of sleep-related breathing disorders, its prevalence ranges from 2% to 4% of the middle-aged population [1]. OSA is a very important diagnosis for physicians to consider because of its strong association with potential cause of the
http://dx.doi.org/10.1016/j.ejcdt.2015.08.017
0422-7638 © 2015 The Authors. Production and hosting by Elsevier B.V. on behalf of The Egyptian Society of Chest Diseases and Tuberculosis. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
most debilitating medical conditions, including hypertension, cardiovascular disease, coronary artery disease, insulinresistance diabetes, depression, and sleepiness-related accidents. However despite being a common disease, OSAS is under recognized by most primary care physicians [2]. In most laboratories, patients with sleep apnea are evaluated for an entire diagnostic night followed by a continuous positive airway pressure (CPAP) titration night. Due to the presence of financial restrictions and waiting lists, sleep centers could solve this problem by investigating and treating patients using split night studies whereby diagnostic polysomnography and continuous positive airway pressure (CPAP) titration are accomplished on the same night rather than the standard two nights polysomnography [3].
In 1997, the American academy of sleep medicine recommended apnea/hypopnea index (AHI) threshold of 40 events/ h or from 20 to 40 events/h in the presence of clinical symptoms and marked desaturations that give permission to undergo split night titration [4]. However new techniques for measuring and scoring sleep disordered breathing events have been administered which may greatly influence the severity of AHI [5,6], thus the threshold of AHI needed for CPAP titration, also may not be considered accurate for doing split-night titration.
Furthermore, it is of concern that split-night polysomnog-raphy cannot accurately assess sleep architecture and sleep disorder severity, and also may not be adequate for optimum titration while rapid eye movement (REM) sleep may not be present adequately in a split-night protocol [7,8]. There are few studies regarding the efficacy of CPAP titration during split night sleep study.
Aim of the study
To evaluate the efficacy of split night CPAP titration in comparison with conventional full night titration in patients with moderate and severe OSAS.
Patients and methods
This randomized parallel study was carried at the sleep laboratory of the Chest department of Assiut University hospital. 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.
Patient selection
We included adult patients with moderate and severe OSAS (diagnosed by polysomnography as total AHI P15). OSAS patients associated with other pulmonary diseases or patients who developed claustrophobia or with technical error during CPAP titration were excluded from the study.
Study design
Over a two year period, we assessed patients coming for polysomnography clinically, radiologically by chest X-ray and functionally (by spirometry and arterial blood gases). Patients matched with the inclusion criteria were enrolled in
the study. Patients were then randomized to either undergo titration in the same diagnostic night or prepared for second full night attended CPAP titration sleep study. Patients were matched for sex, age (±10yrs), body mass index (BMI) (±5 kg/m~2), and severity. Matched patients were enrolled in the study and classified into two groups either split night or full night group.
Polysomnography and CPAP titration
Patients included in the study underwent polysomnography (Sleep Lab Pro, Jaeger, VIASYS Healthcare Hoechberg, Germany). The polysomnogram in each group monitored electroencephalogram (C3-A2, C4-A1), electro-oculogram, elec-tromyogram of the chin, electrocardiogram, nasal and oral airflow (using oronasal flow 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). On CPAP titration, 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 in either of the study groups.
Polysomnography scoring
The polysomnograms were scored manually according to American academy of sleep medicine [5]. Obstructive apnea was reported as a complete cessation of airflow for at least 10 s with a preserved 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 defined 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 as in rapid eye movement (REM) lasting at least 3 s [9].
After manual scoring of the different previous variables, a polysomnographic report was printed including data of sleep [Total seep time (TST) in hours, sleep efficiency, sleep stages %], respiratory [total, NREM and REM AHI and oxygen indices (Desaturation index (DI), average oxygen level, minimum oxygen level, time spent below 90% (T90)] parameters. In CPAP titration report, data about different CPAP pressures applied during the study were detected. The effective CPAP pressure (Peff) was determined as the pressure that alleviated apnoeas and hypopnea (AHI < 5). We considered titration to be successful if the Peff could be obtained together with adequate REM duration of at least 10 min [10].
Statistical analysis
Statistical 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
Table 1 Demographic data of the study groups (n = 120).
Variable Full night study (n = 60) Split night study (n = 60) P-value
Age (mean ± SD) 52.70 ± 9.7 53.1 ± 11.5 0.385
Gender (%)
Male 34 (56.7%) 28 (46.7%)
Female 26 (43.3%) 32 (53.3%) 0.273
BMI (kg/m2) 39.4 ± 9.1 42.2 ± 14.8 0.223
Diagnostic polysomnography
AHI (event/h) 52.8 ± 27.9 53 ± 25.1 0.933
DI (event/h) 59.48 ± 30.7 59.1 ± 35.2 0.955
Average O2 (%) 86.39 ± 13.8 87.2 ± 8.3 0.931
Arousal index (event/h) 17.84 ± 11.72 20.5 ± 10.3 0.074
BMI: body mass index, AHI: apnea hypopnea index, DI: desaturation index.
percentage. For comparison between the split and full night group or between baseline and CPAP, chi-square test was used for analysis of qualitative data and independent sample student t-test for analysis of quantitative data. To determine the best cut-off for AHI and TST for optimum titration in the split night group, we calculated the area under the receiver operating characteristic curve (AUC) and compared the AHI and TST in those with successful titration with those with unsuccessful titration. The difference was considered significant when p < 0.05.
Results
After randomization of all included patients, 60 patients in each group (full night and split night group) were matched for age, sex, BMI and disease severity. Demographic data of the study groups are presented in Table 1.
Table 2 revealed the polysomnographic parameters of split night group patients where there were significantly shorter
TST (2.3 ± 0.8 vs. 3.3 ± 0.72, p = 0.000) and prolonged sleep onset latency (10.4 ± 26.9 vs. 2.56 ± 2.2, p = 0.013) during CPAP titration compared to diagnostic part of the study. Regarding sleep stages, there was significant earlier REM onset latency (10.40 ± 26.9 vs. 19.2 ± 22.29, p = 0.009) with significant increase in REM % TST (i.e. REM rebound) (23.9 ± 8.7 vs. 15.5 ± 15.2) during titration but no significant change in other sleep stages from the diagnostic part of the study. As expected, CPAP significantly improved all respiratory parameters (p < 0.05). On comparing the CPAP titration part with full night CPAP titration (Table 3), besides the expected shorter TST (2.34 ± 0.82 vs. 4.023 ±1.1, p = 0.000), sleep efficiency (75.9 ± 15.7 vs. 81.5 ± 10.5, p = 0.024) was significantly shorter. As regards to sleep stages, stage 1% TST was significantly higher (22.3 ± 14 vs. 17.9 ± 15.8, p = 0.013) but REM % TST (23.9 ± 18.7 vs. 31.3 ± 14.8, p = 0.019) was significantly lower. There were no significant differences in all respiratory parameters between the two groups (p > 0.05).
Table 2 Polysomnographic parameters of the split night group (n = 60).
Variable Diagnostic part (n = 60) CPAP part (n = 60) P-value
Mean ± SD Mean ± SD
Sleep parameters
TST (h) 3.3 ± 0.72 2.3 ± 0.8 0.000*
Sleep efficiency (%) 79 ± 16.8 75.9 ± 15.7 0.12
Sleep onset latency (min) 2.56 ± 2.2 10.4 ± 26.9 0.013*
REM onset latency (min) 19.2 ± 22.29 10.40 ± 26.9 0.009*
Stage 1 (%) 24.7 ± 12.73 22.3 ± 14 0.456
Stage 2 (%) 33.2 ± 14.1 34.53 ± 16.6 0.233
Stage 3 (%) 17.7 ± 15.6 18.8 ± 12.27 0.189
REM (%) 15.5 ± 15.2 23.9 ± 18.7 0.007*
Respiratory parameters
AHI (event/h) 53 ± 25.2 7.9 ± 9.3 0.000*
DI (event/h) 59 ± 35.2 14.5 ± 17.2 0.000*
Average O2 (%) 80.1 ± 8.26 88.6 ± 8.5 0.004*
Minimum O2 (%) 64.4 ± 15.7 77.9 ± 13.4 0.000*
T90 (min) 53.6 ± 42 8.4 ± 12.5 0.000*
Arousal index (event/h) 11.4 ± 10.3 7.6 ± 9.8 0.053*
TST = total sleep time, REM = rapid eye movement, AHI = apnea hypopnea index, DI = desaturation index, T90 = time spent below 90%
in minutes.
Significant.
Table 3 Polysomnographic parameters of the study groups on CPAP (n = 120).
Variable Full night study (n = 60) Split night study (n = 60) P-value
Mean ± SD Mean ± SD
Sleep parameters
TST (h) 4.023 ± 1.1 2.34 ± 0.82 0.000*
Sleep efficiency (%) 81.5 ± 10.5 75.9 ± 15.7 0.024*
Sleep onset latency (min) 2.7 ± 3.8 10.4 ± 26.9 0.010*
REM onset latency (min) 10.31 ± 23.6 14.2 ± 22.3 0.354
Stage 1 (%) 17.9 ± 15.8 22.3 ± 14 0.013*
Stage 2 (%) 26.23 ± 14.2 34.53 ± 16.6 0.135
Stage 3 (%) 23.2 ± 14.9 18.8 ± 12.27 0.444
REM (%) 31.3 ± 14.8 23.9 ± 18.7 0.019*
Respiratory parameters
AHI (event/h) 7.67 ± 5.8 7.9 ± 9.4 0.834
DI (event/h) 10.03 ± 17.5 14.53 ± 17.2 0.158
Average O2 (%) 89.3 ± 7.7 88.6 ± 8.5 0.678
Minimum O2 (%) 72.43 ± 18 77.97 ± 13.4 0.079
T90 (min) 7.03 ± 12.88 8.46 ± 12.52 0.546
Arousal index (event/h) 7.44 ± 10.38 7.6 ± 9.8 0.93
CPAP titration
CPAP Peff (cm H2O) 8.85 ± 2 8.88 ± 2.3 0.978
TST = total sleep time, REM = rapid eye movement, AHI = apnea hypopnea index, DI = desaturation index, T90 = time spent below 90%
in minutes, CPAP = continuous positive airway pressure, Peff = effective pressure.
Significant.
On using the criteria of successful titration, unsuccessful CPAP titration was significantly higher in split night group than the full night group (30 (50%) vs. 16 (35.5%), p = 0.025) (Fig. 1). Patients who could reach successful CPAP titration during split night titration were significantly less obese (BMI was 36.3 ± 12.6 vs. 48 ± 14.6, p = 0.002) and reported significantly longer TST (2.8 ± 0.9 vs. 2 ± 0.6, p = 0.001) and REM % TST (30.9 ± 16.1 vs. 16.9 ± 18.9, p = 0.003) compared to those who could not reach successful titration (Table 4).
To determine the optimum AHI and TST duration that was needed for successful titration in split night sleep study, we analyzed the data using the receiving operating characteristic (ROC) curve. We identified AHI >36.4 as the optimum cut
off for successful titration with AUC 0.5 (CI 95% [0.500.80]) giving 73.5% sensitivity and 43.3% specificity (Fig. 2). The patient should sleep more than 2.45 h to optimize successful titration giving 74% sensitivity and 70% specificity with AUC 0.7 (CI 95% [0.29-0.61]) (Fig. 3).
Discussion
Split-night polysomnography was introduced to obtain diagnosis and determine an effective CPAP on a single night that would be convenient and cost effective. Underestimation of the severity of sleep apnea (no or minimal REM sleep in the first half of the night) and inadequate time for CPAP titration are potential disadvantages of this approach that may require
Figure 1 Comparison between the split night group and the full night group regarding successful titration. Unsuccessful titration was 30 patients (50%) in split night group vs. 16 patients (35.5%) in full night group (p = 0.025).
Table 4 Possible factors associated with successful titration in split night group patients (n = 60).
Variable Successful titration (n = 30) Unsuccessful titration (n = 30) P-value
Age (mean ± SD) 55.73 ± 11.9 58.47 ± 11 0.362
Gender %
Male 12 (40.0%) 16 (53.3%) 0.301
Female 18 (56.2%) 14 (43.8%)
BMI (kg/m2) 36.3 ± 12.6 48 ± 14.6 0.002*
Diagnostic part of polysomnography
TST (h) 3.2 ± 0.7 3.4 ± 0.7 0.358
Stage 1 (%) 16.4 ± 9.4 25.1 ± 14.2 0.007
Stage 2 (%) 25.7 ± 12.8 26.7 ± 15.5 0.78
Stage 3 (%) 23.9 ± 15.6 21.6 ± 15.8 0.57
REM (%) 29.7 ± 18.2 23.3 ± 12.1 0.114
AHI (event/h) 47 ± 20.5 58.9 ± 28.2 0.05
DI (event/h) 58.27 ± 35.7 59.8 ± 35 0.862
Minimum O2 (%) 66.67 ± 15.5 62.13 ± 15.8 0.268
CPAP part of polysomnography
TST (h) 3.1 ± 0.9 2.15 ± 0.6 0.001*
Stage 1 (%) 32.4 ± 27.2 45.4 ± 30.1 0.085
Stage 2 (%) 17.2 ± 15.3 18.6 ± 16.5 0.722
Stage 3 (%) 18.9 ± 15.5 18.7 ± 20.9 0.961
REM (%) 30.9 ± 16.1 16.9 ± 18.9 0.003*
BMI: body mass index, TST = total sleep time, REM = rapid eye movement, AHI = apnea hypopnea index, DI = desaturation index.
Significant.
the need to repeat full second night CPAP titration which further increases the cost [7,8].
This study revealed that split night CPAP titration significantly improved all respiratory parameters which were comparable to full night study; however, we did not report improvement in sleep architecture during split night CPAP titration. TST was significantly shorter with significant prolongation in sleep and REM onset latency duration that might reflect the inability to sleep following sleep disruption using split night protocol. Similarly, Yamashiro et al. [11] showed that there was a significant reduction in AHI and percent TST below 90% SaO2 during the split night CPAP compared
with baseline; they suggested that a split-night protocol was as effective as a second night in reducing apnea and hypopnea index, improving oxygenation, and reducing arousals. To our knowledge, there is no studies discussed the immediate effect of split night CPAP titration on sleep architecture. However, studies [12,13] that were carried out during full night CPAP titration indicated that even short-term exposure to CPAP improved sleep architecture with significant decrease in light sleep (stage 1 and stage 2) percent and significant increase with in both deep sleep (i.e. stage 3 and 4) and REM stage as a % of total sleep time.
Although in this work we found that REM % TST was significantly increased during split night study compared to base-
Figure 2 Area under receiving operating characteristic curve for optimum baseline AHI needed for successful titration in split night sleep study. AHI >36.4 identified the optimum cut off for successful titration with AUC 0.5 (CI 95% [0.50-0.80]) giving 73.5% sensitivity and 43.3% specificity.
Figure 3 Area under receiving operating characteristic curve for optimum TST (total sleep time) needed for successful titration in split night sleep study. During CPAP titration, TST >2.45 h was needed for successful titration with AUC 0.7 (CI 95% [0.29-0.61]) giving 74% sensitivity and 70% specificity.
line, it was significantly lower than the full night group (23.9 ± 18.7 vs. 31.3 ± 14.8, p = 0.019). However, other studies [3,14] reported adequate REM sleep during the titration portion of their split-night study which was comparable to full night study (24.1% vs. 22%). It is known that REM rebound phenomenon (i.e. increase REM above baseline and normative values) was an important phenomenon that usually occurred following CPAP titration due to depletion of REM sleep in OSA patients. It was considered a regulatory mechanism of sleep homeostasis that returned sleep to normal architecture after previous depletion of REM sleep. Both subjective improvements in sleep quality and effective treatment of OSAS patients were associated with REM sleep rebound following the first night of CPAP treatment [15,16].
When evaluating the adequacy of CPAP prescription by comparing split-night versus full-night polysomnography, this study achieved successful CPAP titration in 50% of patients during split night study which was significantly less than full night titration (59.5% vs. 50%, p = 0.025) despite the effective CPAP pressure being similar between the two groups. In a retrospective review of 412 consecutive patients with an apnea index p20/h, Iber and coworkers [17] found that 78% of the CPAP titrations were adequate (the lower of AHI p20/h or 50% reduction during supine REM sleep). Yamashiro and Kryger [11] found that patients with an AHI p40/h had similar optimal pressures on a split-night and subsequent full-night CPAP titration. Conversely, Okic et al. [18] in their study of patients with severe OSA (AHI >40/h), split-night CPAP titration resulted in a mean pressure 2.5 cm H2O higher than that of full-night titration.
This study revealed that during split night titration part, the more REM percentage was associated with successful CPAP titration. Aldrich et al. have suggested that adequate split-night studies should include REM sleep during CPAP titration at the final CPAP pressure [19]. On the other hand, in a split-night study with successful titration, patients with REM (n = 33) at final pressure were comparable to patients without REM (n = 8) regarding disease severity and CPAP use. They suggested that the presence of REM sleep may not be necessary for adequate CPAP pressure titration; but the authors limited these results by the small numbers of patients studied without REM [15].
On assessing the optimum AHI needed for successful titration in split night sleep study, we found diagnostic AHI >36.5 as the optimum cut off for successful split night titration with AUC 0.5 (CI 95% [0.50-0.80]) giving 73.5% sensitivity and 43.3% specificity and at least 2.75 h required for CPAP titration. Strollo et al. required an AHI of >30 in the diagnostic half of the split-night before proceeding to CPAP titration [20]. Also Kushida and his colleagues have suggested criteria for a split-night study: a minimum of 2 h of diagnostic monitoring, AHI >40/h or 20 to 40/h with severe desaturation or other indications for an immediate titration, and 3 h remaining for the CPAP titration [21,22]. Medicare guidelines in some locales require at least 2 h of sleep during the diagnostic portion [23]. More recently, Khawaja et al. [24] showed that AHI derived from the first 2 or 3 h of sleep was of sufficient diagnostic accuracy to rule-in OSA at an AHI threshold of 5 in patients suspected of having OSA but that study did not assess adequate titration at this level of AHI.
Conclusion
Split night sleep study is more commonly associated with unsuccessful CPAP titration than full night titration but successful titration could be obtained during split night titration in patients with severe AHI >36.5 event/h.
Conflict of interest
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