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Weight loss alters severity of individual nocturnal respiratory events depending on sleeping position
This content has been downloaded from IOPscience. Please scroll down to see the full text. 2014 Physiol. Meas. 35 2037 (http://iopscience.iop.org/0967-3334/35/10/2037) View the table of contents for this issue, or go to the journal homepage for more Download details: IP Address: 132.174.250.220 This content was downloaded on 30/08/2017 at 15:55 Please note that terms and conditions apply.
You may also be interested in: Novel parameters reflect changes in morphology of respiratory events during weight loss A Kulkas, T Leppänen, J Sahlman et al. Gender differences in severity of desaturation events following hypopnea and obstructive apnea events in adults during sleep Antti Kulkas, Brett Duce, Timo Leppänen et al. Sleep apnea: a review of diagnostic sensors, algorithms, and therapies Mehdi Shokoueinejad, Chris Fernandez, Emily Carroll et al. Hidden Markov modelling of intra-snore episode behavior of acoustic characteristics of obstructive sleep apnea patients Dulip L Herath, Udantha R Abeyratne and Craig Hukins A review of signals used in sleep analysis A Roebuck, V Monasterio, E Gederi et al. Watch-PAT for sleep apnea recording Thomas Penzel, Karl Kesper, Iris Pinnow et al. A review of preventing central sleep apnea by inspired CO2 A Mulchrone, M Shokoueinejad and J Webster Automatic classification of apnea/hypopnea events through sleep/wake states and severity of SDB from a pulse oximeter Jong-Uk Park, Hyo-Ki Lee, Junghun Lee et al.
Institute of Physics and Engineering in Medicine Physiol. Meas. 35 (2014) 2037–2052
Physiological Measurement doi:10.1088/0967-3334/35/10/2037
Weight loss alters severity of individual nocturnal respiratory events depending on sleeping position A Kulkas1, T Leppänen2,3, J Sahlman4,5, P Tiihonen2, E Mervaala2,5, J Kokkarinen6, J Randell6, J Seppä4,5, J Töyräs2,3 and H Tuomilehto7,8 1
Department of Clinical Neurophysiology, Seinäjoki Central Hospital, Seinäjoki, Finland Department of Clinical Neurophysiology, Kuopio University Hospital, Kuopio, Finland 3 Department of Applied Physics, University of Eastern Finland, Kuopio, Finland 4 Department of Otorhinolaryngology, Kuopio University Hospital, Kuopio, Finland 5 Institute of Clinical Medicine, Faculty of Health Sciences, University of Eastern Finland, Kuopio, Finland 6 Department of Respiratory Medicine, Kuopio University Hospital, Kuopio, Finland 7 Oivauni Sleep Clinic, Kuopio and Tampere, Finland 8 Institute of Public Health and Clinical Nutrition, Department of Clinical Nutrition, University of Eastern Finland, Kuopio, Finland 2
E-mail: [email protected] Received 16 May 2014, revised 21 July 2014 Accepted for publication 29 July 2014 Published 19 September 2014 Abstract
Weight loss is an effective treatment for obstructive sleep apnea (OSA). The mechanisms of how weight loss affects nocturnal breathing are not fully understood. The severity of OSA is currently estimated by the number of respiratory events per hour of sleep (i.e. apnea-hypopnea-index, AHI). AHI neglects duration and morphology of individual respiratory events, which describe the severity of individual events. In the current paper, we investigate the novel Adjusted-AHI parameter (incorporating individual event severity) and AHI after weight loss in relation to sleeping position. It was hypothesised that there are positional differences in individual event severity changes during weight loss. Altogether, 32 successful (> 5% of weight) and 34 unsuccessful weight loss patients at baseline and after 1 year follow-up were analysed. The results revealed that individual respiratory event severity was reduced differently in supine and non-supine positions during weight loss. During weight loss, AHI was reduced by 54% (p = 0.004) and 74% (p 5%
Baseline
1 year
Baseline
23 11 90.4 (75.0 − 118.1) 53.4 (37.7 − 68.8) 31.4 (26.0 − 39.0) 106 (85 − 132)
25 7 90.2 (73.2 − 124.2) 98.8 (74.6 − 137.7)* 54.7 (38.7 − 70.2)# 47.8 (32.5 − 63.3) * 31.2 (27.1 − 41.0) 32.5 (28.4 − 41.6) 102 (85 − 138)# 108 (95 − 135)
86.8 (64.4 − 122.1)# 49.1 (33.8 − 64.7)# 29.2 (24.5 − 36.9)# 99 (84 − 140)#
8 (2 − 21) 6 (18)
8 (2 − 18)# 4 (12)
5 (1 − 17)# 8 (25)
11 (2 − 17) 8 (25)
1 year
*
Significantly different (p 5 events/h
Collection of demographic data Written informed consent
Randomization 87 patients
Intervention group 42 patients
Control group 45 patients
1-year follow-up polygraphy recording and collection of demographic data
66 patients were included in the study 21 patients either dropped out or were excluded due to partially failed follow-up polygraphy recording
Successful weight loss group weight loss > 5% 32 patients polygraphy analysis
Unsuccessful weight loss group 34 patients polygraphy analysis
Figure 1. Flow chart describing the study protocol.
their baseline weight during the 1 year trial period. The remaining 34 patients who were not able to lose weight > 5%, were assigned to the unsuccessful weight loss group. A flow chart of the study protocol is presented in figure 1. AHI, ODI, and the novel parameters (obstruction severity and Adjusted-AHI) were determined for the total analysed period and for supine and non-supine positions. Additionally, the amount of time saturation levels were under 90% (SpO2 5%
100
Supine 0 year, Total number of events 1078 Supine 1 year, Total number of events 715
250 200 150 100
0 0
100
350
Nonsupine 0 year, Total number of events 1351 Nonsupine 1 year, Total number of events 1089
300
Number of events
Number of events
20
50
250 200 150 100 50 0 0
100
300
150
300
150
350
Supine 0 year, Total number of events 1912 Supine 1 year, Total number of events 2188
200
350
200
0 0
100
250
0 0
250
50
Number of events
0 0
0 year, Total number of events 2074 1 year, Total number of events 1122
300
Number of events
300
Number of events
Successful weight loss > 5% 350
0 year, Total number of events 3263 1 year, Total number of events 3277
20
40
60
80
Obstruction duration (s) Successful weight loss > 5%
100
Nonsupine 0 year, Total number of events 996 Nonsupine 1 year, Total number of events 407
250 200 150 100 50
20
40
60
Obstruction duration (s)
80
100
0 0
20
40
60
Obstruction duration (s)
80
100
Figure 2. Distributions of individual obstruction duration events (apnea and hypopnea event durations) in unsuccessful and successful weight loss groups at baseline (0 month) and at 1 year. Along weight loss, the number of events was reduced in the supine and non-supine positions. In the non-supine position, the number of events was reduced in a wider range of severities, and in the supine position, the reduction was focused on less severe events. The differences between baseline and 1 year time points were statistically significant in all distributions (mixed model analysis).
and unsuccessful weight loss) were used as fixed effects, the patient was used as random effect, and the individual event data were used as the dependent variables. Visual evaluation was performed for the model residual histograms to ensure they were normally distributed. p 5%
350
50
250 200 150 100 50
0 0
20
40
60
Desaturation duration (s) Unsuccessful weight loss
80
0 0
100
350
Nonsupine 0 year, Total number of events 1264 Nonsupine 1 year, Total number of events 1067
300
Number of events
Number of events
200
0 0
100
Number of events
Number of events
40
Desaturation duration (s) Unsuccessful weight loss
Supine 0 year, Total number of events 1774 Supine 1 year, Total number of events 2102
300
300
250
50
0 0
350
0 year, Total number of events 1870 1 year, Total number of events 1117
300
Number of events
300
Number of events
Successful weight loss > 5% 350
0 year, Total number of events 3038 1 year, Total number of events 3169
250 200 150 100 50 0 0
20
40
60
80
Desaturation duration (s) Successful weight loss > 5%
100
Nonsupine 0 year, Total number of events 921 Nonsupine 1 year, Total number of events 410
250 200 150 100 50
20
40
60
Desaturation duration (s)
80
100
0 0
20
40
60
Desaturation duration (s)
80
100
Figure 3. Distributions of individual desaturation duration events in unsuccessful and successful weight loss groups at baseline (0 month) and at 1 year. Along weight loss, the number of events was reduced in supine and non-supine positions. In the non-supine position, the number of events was reduced in a wider range of severities and in the supine position, the reduction was focused on less severe events. The differences between baseline and 1 year time points were statistically significant in all distributions (mixed model analysis).
3. Results AHI was significantly reduced in the weight loss group in both supine and non-supine positions (table 3). A similar finding was seen with ODI and in the time SpO2 5%
Unsuccessful weight loss 600
400 300 200 100
600
Number of events
500
50
100
150
Desaturation severity (s%) Unsuccessful weight loss
500
200 100 50
100
150
Desaturation severity (s%) Unsuccessful weight loss
100
150
200
Supine 0 year, Total number of events 949 Supine 1 year, Total number of events 707
400 300 200
0 0
200
600
Nonsupine 0 year, Total number of events 1264 Nonsupine 1 year, Total number of events 1067
500
400 300 200 100 0 0
50
Desaturation severity (s%) Successful weight loss > 5%
100
Number of events
Number of events
500
200
600
Supine 0 year, Total number of events 1774 Supine 1 year, Total number of events 2102
300
600
300
0 0
200
400
0 0
400
100
Number of events
0 0
0 year, Total number of events 1870 1 year, Total number of events 1117
500
Number of events
500
Number of events
600
0 year, Total number of events 3038 1 year, Total number of events 3169
50
100
150
Desaturation severity (s%) Successful weight loss > 5%
200
Nonsupine 0 year, Total number of events 921 Nonsupine 1 year, Total number of events 410
400 300 200 100
50
100
150
Desaturation severity (s%)
200
0 0
50
100
150
Desaturation severity (s%)
200
Figure 4. Distributions of individual desaturation severity events (desaturation area) in unsuccessful and successful weight loss groups at baseline (0 month) and at 1 year. Along weight loss, the number of events was reduced in supine and non-supine positions. In the non-supine position, the number of events was reduced in a wider range of severities and in the supine position, the reduction was focused on less severe events. The differences between baseline and 1 year time points were statistically significant in all distributions (mixed model analysis).
Interestingly, based on visual inspection of the individual event distributions (figures 2–5), the decrease in the number of individual respiratory events was more focused on less severe events in supine position. In the non-supine position, the reduction in the number of events 2045
A Kulkas et al
Physiol. Meas. 35 (2014) 2037
Unsuccessful weight loss
Successful weight loss > 5% 1000
0 year, Total number of events 3021 1 year, Total number of events 3125
800
Number of events
Number of events
1000
600 400 200 0 0
800 600 400 200
2000
4000
6000
2
8000
0 0
10000
Obstruction severity (s %) Unsuccessful weight loss 1000
Supine 0 year, Total number of events 1764 Supine 1 year, Total number of events 2083
800 600 400 200 0 0
2000
4000
6000
2
8000
2
8000
10000
Supine 0 year, Total number of events 938 Supine 1 year, Total number of events 674
600 400
0 0
10000
2000
4000
6000
2
8000
10000
Obstruction severity (s %) Successful weight loss > 5% 1000
Nonsupine 0 year, Total number of events 1257 Nonsupine 1 year, Total number of events 1042
Number of events
Number of events
6000
200
800 600 400 200 0 0
4000
800
Obstruction severity (s %) Unsuccessful weight loss 1000
2000
Obstruction severity (s %) Successful weight loss > 5%
Number of events
Number of events
1000
0 year, Total number of events 1848 1 year, Total number of events 1064
Nonsupine 0 year, Total number of events 910 Nonsupine 1 year, Total number of events 390
800 600 400 200
2000
4000
6000
2
8000
10000
Obstruction severity (s %)
0 0
2000
4000
6000
2
8000
10000
Obstruction severity (s %)
Figure 5. Distributions of individual obstruction severity events (apnea and hypopnea event duration multiplied with related desaturation area) in unsuccessful and successful weight loss groups at baseline (0 month) and at 1 year. Along weight loss, the number of events was reduced in supine and non-supine positions. In the non-supine position, the number of events was reduced in a wider range of severities and in the supine position, the reduction was focused on less severe events. The differences between baseline and 1 year time points were statistically significant in all distributions (mixed model analysis).
was more evenly distributed over a wide range of severities (figures 2–5). General reduction in the number of respiratory events was seen during weight loss as indicated by AHI and ODI. The number of apnea and hypopnea events with shorter duration was reduced more for the supine position than the number of events with longer duration (figure 2). Additionally, 2046
AHI (1 h−1) AHI supine (1 h−1) AHI nonsupine (1 h−1) ODI (1 h−1) ODI supine (1 h−1) ODI nonsupine (1 h−1) ObsSev (s%) ObsSev supine (s%) ObsSev nonsupine (s%) Adjusted-AHI (1 h−1) Adjusted-AHI supine (1 h−1) Adjusted-AHI nonsupine (1 h−1) SpO2
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My IOPscience
Weight loss alters severity of individual nocturnal respiratory events depending on sleeping position
This content has been downloaded from IOPscience. Please scroll down to see the full text. 2014 Physiol. Meas. 35 2037 (http://iopscience.iop.org/0967-3334/35/10/2037) View the table of contents for this issue, or go to the journal homepage for more Download details: IP Address: 132.174.250.220 This content was downloaded on 30/08/2017 at 15:55 Please note that terms and conditions apply.
You may also be interested in: Novel parameters reflect changes in morphology of respiratory events during weight loss A Kulkas, T Leppänen, J Sahlman et al. Gender differences in severity of desaturation events following hypopnea and obstructive apnea events in adults during sleep Antti Kulkas, Brett Duce, Timo Leppänen et al. Sleep apnea: a review of diagnostic sensors, algorithms, and therapies Mehdi Shokoueinejad, Chris Fernandez, Emily Carroll et al. Hidden Markov modelling of intra-snore episode behavior of acoustic characteristics of obstructive sleep apnea patients Dulip L Herath, Udantha R Abeyratne and Craig Hukins A review of signals used in sleep analysis A Roebuck, V Monasterio, E Gederi et al. Watch-PAT for sleep apnea recording Thomas Penzel, Karl Kesper, Iris Pinnow et al. A review of preventing central sleep apnea by inspired CO2 A Mulchrone, M Shokoueinejad and J Webster Automatic classification of apnea/hypopnea events through sleep/wake states and severity of SDB from a pulse oximeter Jong-Uk Park, Hyo-Ki Lee, Junghun Lee et al.
Institute of Physics and Engineering in Medicine Physiol. Meas. 35 (2014) 2037–2052
Physiological Measurement doi:10.1088/0967-3334/35/10/2037
Weight loss alters severity of individual nocturnal respiratory events depending on sleeping position A Kulkas1, T Leppänen2,3, J Sahlman4,5, P Tiihonen2, E Mervaala2,5, J Kokkarinen6, J Randell6, J Seppä4,5, J Töyräs2,3 and H Tuomilehto7,8 1
Department of Clinical Neurophysiology, Seinäjoki Central Hospital, Seinäjoki, Finland Department of Clinical Neurophysiology, Kuopio University Hospital, Kuopio, Finland 3 Department of Applied Physics, University of Eastern Finland, Kuopio, Finland 4 Department of Otorhinolaryngology, Kuopio University Hospital, Kuopio, Finland 5 Institute of Clinical Medicine, Faculty of Health Sciences, University of Eastern Finland, Kuopio, Finland 6 Department of Respiratory Medicine, Kuopio University Hospital, Kuopio, Finland 7 Oivauni Sleep Clinic, Kuopio and Tampere, Finland 8 Institute of Public Health and Clinical Nutrition, Department of Clinical Nutrition, University of Eastern Finland, Kuopio, Finland 2
E-mail: [email protected] Received 16 May 2014, revised 21 July 2014 Accepted for publication 29 July 2014 Published 19 September 2014 Abstract
Weight loss is an effective treatment for obstructive sleep apnea (OSA). The mechanisms of how weight loss affects nocturnal breathing are not fully understood. The severity of OSA is currently estimated by the number of respiratory events per hour of sleep (i.e. apnea-hypopnea-index, AHI). AHI neglects duration and morphology of individual respiratory events, which describe the severity of individual events. In the current paper, we investigate the novel Adjusted-AHI parameter (incorporating individual event severity) and AHI after weight loss in relation to sleeping position. It was hypothesised that there are positional differences in individual event severity changes during weight loss. Altogether, 32 successful (> 5% of weight) and 34 unsuccessful weight loss patients at baseline and after 1 year follow-up were analysed. The results revealed that individual respiratory event severity was reduced differently in supine and non-supine positions during weight loss. During weight loss, AHI was reduced by 54% (p = 0.004) and 74% (p 5%
Baseline
1 year
Baseline
23 11 90.4 (75.0 − 118.1) 53.4 (37.7 − 68.8) 31.4 (26.0 − 39.0) 106 (85 − 132)
25 7 90.2 (73.2 − 124.2) 98.8 (74.6 − 137.7)* 54.7 (38.7 − 70.2)# 47.8 (32.5 − 63.3) * 31.2 (27.1 − 41.0) 32.5 (28.4 − 41.6) 102 (85 − 138)# 108 (95 − 135)
86.8 (64.4 − 122.1)# 49.1 (33.8 − 64.7)# 29.2 (24.5 − 36.9)# 99 (84 − 140)#
8 (2 − 21) 6 (18)
8 (2 − 18)# 4 (12)
5 (1 − 17)# 8 (25)
11 (2 − 17) 8 (25)
1 year
*
Significantly different (p 5 events/h
Collection of demographic data Written informed consent
Randomization 87 patients
Intervention group 42 patients
Control group 45 patients
1-year follow-up polygraphy recording and collection of demographic data
66 patients were included in the study 21 patients either dropped out or were excluded due to partially failed follow-up polygraphy recording
Successful weight loss group weight loss > 5% 32 patients polygraphy analysis
Unsuccessful weight loss group 34 patients polygraphy analysis
Figure 1. Flow chart describing the study protocol.
their baseline weight during the 1 year trial period. The remaining 34 patients who were not able to lose weight > 5%, were assigned to the unsuccessful weight loss group. A flow chart of the study protocol is presented in figure 1. AHI, ODI, and the novel parameters (obstruction severity and Adjusted-AHI) were determined for the total analysed period and for supine and non-supine positions. Additionally, the amount of time saturation levels were under 90% (SpO2 5%
100
Supine 0 year, Total number of events 1078 Supine 1 year, Total number of events 715
250 200 150 100
0 0
100
350
Nonsupine 0 year, Total number of events 1351 Nonsupine 1 year, Total number of events 1089
300
Number of events
Number of events
20
50
250 200 150 100 50 0 0
100
300
150
300
150
350
Supine 0 year, Total number of events 1912 Supine 1 year, Total number of events 2188
200
350
200
0 0
100
250
0 0
250
50
Number of events
0 0
0 year, Total number of events 2074 1 year, Total number of events 1122
300
Number of events
300
Number of events
Successful weight loss > 5% 350
0 year, Total number of events 3263 1 year, Total number of events 3277
20
40
60
80
Obstruction duration (s) Successful weight loss > 5%
100
Nonsupine 0 year, Total number of events 996 Nonsupine 1 year, Total number of events 407
250 200 150 100 50
20
40
60
Obstruction duration (s)
80
100
0 0
20
40
60
Obstruction duration (s)
80
100
Figure 2. Distributions of individual obstruction duration events (apnea and hypopnea event durations) in unsuccessful and successful weight loss groups at baseline (0 month) and at 1 year. Along weight loss, the number of events was reduced in the supine and non-supine positions. In the non-supine position, the number of events was reduced in a wider range of severities, and in the supine position, the reduction was focused on less severe events. The differences between baseline and 1 year time points were statistically significant in all distributions (mixed model analysis).
and unsuccessful weight loss) were used as fixed effects, the patient was used as random effect, and the individual event data were used as the dependent variables. Visual evaluation was performed for the model residual histograms to ensure they were normally distributed. p 5%
350
50
250 200 150 100 50
0 0
20
40
60
Desaturation duration (s) Unsuccessful weight loss
80
0 0
100
350
Nonsupine 0 year, Total number of events 1264 Nonsupine 1 year, Total number of events 1067
300
Number of events
Number of events
200
0 0
100
Number of events
Number of events
40
Desaturation duration (s) Unsuccessful weight loss
Supine 0 year, Total number of events 1774 Supine 1 year, Total number of events 2102
300
300
250
50
0 0
350
0 year, Total number of events 1870 1 year, Total number of events 1117
300
Number of events
300
Number of events
Successful weight loss > 5% 350
0 year, Total number of events 3038 1 year, Total number of events 3169
250 200 150 100 50 0 0
20
40
60
80
Desaturation duration (s) Successful weight loss > 5%
100
Nonsupine 0 year, Total number of events 921 Nonsupine 1 year, Total number of events 410
250 200 150 100 50
20
40
60
Desaturation duration (s)
80
100
0 0
20
40
60
Desaturation duration (s)
80
100
Figure 3. Distributions of individual desaturation duration events in unsuccessful and successful weight loss groups at baseline (0 month) and at 1 year. Along weight loss, the number of events was reduced in supine and non-supine positions. In the non-supine position, the number of events was reduced in a wider range of severities and in the supine position, the reduction was focused on less severe events. The differences between baseline and 1 year time points were statistically significant in all distributions (mixed model analysis).
3. Results AHI was significantly reduced in the weight loss group in both supine and non-supine positions (table 3). A similar finding was seen with ODI and in the time SpO2 5%
Unsuccessful weight loss 600
400 300 200 100
600
Number of events
500
50
100
150
Desaturation severity (s%) Unsuccessful weight loss
500
200 100 50
100
150
Desaturation severity (s%) Unsuccessful weight loss
100
150
200
Supine 0 year, Total number of events 949 Supine 1 year, Total number of events 707
400 300 200
0 0
200
600
Nonsupine 0 year, Total number of events 1264 Nonsupine 1 year, Total number of events 1067
500
400 300 200 100 0 0
50
Desaturation severity (s%) Successful weight loss > 5%
100
Number of events
Number of events
500
200
600
Supine 0 year, Total number of events 1774 Supine 1 year, Total number of events 2102
300
600
300
0 0
200
400
0 0
400
100
Number of events
0 0
0 year, Total number of events 1870 1 year, Total number of events 1117
500
Number of events
500
Number of events
600
0 year, Total number of events 3038 1 year, Total number of events 3169
50
100
150
Desaturation severity (s%) Successful weight loss > 5%
200
Nonsupine 0 year, Total number of events 921 Nonsupine 1 year, Total number of events 410
400 300 200 100
50
100
150
Desaturation severity (s%)
200
0 0
50
100
150
Desaturation severity (s%)
200
Figure 4. Distributions of individual desaturation severity events (desaturation area) in unsuccessful and successful weight loss groups at baseline (0 month) and at 1 year. Along weight loss, the number of events was reduced in supine and non-supine positions. In the non-supine position, the number of events was reduced in a wider range of severities and in the supine position, the reduction was focused on less severe events. The differences between baseline and 1 year time points were statistically significant in all distributions (mixed model analysis).
Interestingly, based on visual inspection of the individual event distributions (figures 2–5), the decrease in the number of individual respiratory events was more focused on less severe events in supine position. In the non-supine position, the reduction in the number of events 2045
A Kulkas et al
Physiol. Meas. 35 (2014) 2037
Unsuccessful weight loss
Successful weight loss > 5% 1000
0 year, Total number of events 3021 1 year, Total number of events 3125
800
Number of events
Number of events
1000
600 400 200 0 0
800 600 400 200
2000
4000
6000
2
8000
0 0
10000
Obstruction severity (s %) Unsuccessful weight loss 1000
Supine 0 year, Total number of events 1764 Supine 1 year, Total number of events 2083
800 600 400 200 0 0
2000
4000
6000
2
8000
2
8000
10000
Supine 0 year, Total number of events 938 Supine 1 year, Total number of events 674
600 400
0 0
10000
2000
4000
6000
2
8000
10000
Obstruction severity (s %) Successful weight loss > 5% 1000
Nonsupine 0 year, Total number of events 1257 Nonsupine 1 year, Total number of events 1042
Number of events
Number of events
6000
200
800 600 400 200 0 0
4000
800
Obstruction severity (s %) Unsuccessful weight loss 1000
2000
Obstruction severity (s %) Successful weight loss > 5%
Number of events
Number of events
1000
0 year, Total number of events 1848 1 year, Total number of events 1064
Nonsupine 0 year, Total number of events 910 Nonsupine 1 year, Total number of events 390
800 600 400 200
2000
4000
6000
2
8000
10000
Obstruction severity (s %)
0 0
2000
4000
6000
2
8000
10000
Obstruction severity (s %)
Figure 5. Distributions of individual obstruction severity events (apnea and hypopnea event duration multiplied with related desaturation area) in unsuccessful and successful weight loss groups at baseline (0 month) and at 1 year. Along weight loss, the number of events was reduced in supine and non-supine positions. In the non-supine position, the number of events was reduced in a wider range of severities and in the supine position, the reduction was focused on less severe events. The differences between baseline and 1 year time points were statistically significant in all distributions (mixed model analysis).
was more evenly distributed over a wide range of severities (figures 2–5). General reduction in the number of respiratory events was seen during weight loss as indicated by AHI and ODI. The number of apnea and hypopnea events with shorter duration was reduced more for the supine position than the number of events with longer duration (figure 2). Additionally, 2046
AHI (1 h−1) AHI supine (1 h−1) AHI nonsupine (1 h−1) ODI (1 h−1) ODI supine (1 h−1) ODI nonsupine (1 h−1) ObsSev (s%) ObsSev supine (s%) ObsSev nonsupine (s%) Adjusted-AHI (1 h−1) Adjusted-AHI supine (1 h−1) Adjusted-AHI nonsupine (1 h−1) SpO2
