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The effects of body position on the distribution of obstructive, mixed and central sleep apnoea

Authors:

Abstract

Background: Obstructive sleep apnoea is commonly aggravated by the supine body position. The impact of body position on the severity of mixed and central sleep apnoeas is understudied. Objectives: To evaluate the impact of body position on obstructive, mixed and central apnoea indices in subjects presenting with this triform of sleep apnoea during a single polysomnogram. Methods: We retrospectively analysed 26 polysomnograms where obstructive, mixed and central apnoeas each occurred at a rate >5/hr. Comparisons between lateral and supine body positions were made for obstructive apnoea index (OAI), mixed apnoea index (MAI), central apnoea index (CAI), apnoea-hypopnoea index (AHI) and obstructive apnoea-hypopnoea index (OAHI). Results: Mean (SD) apnoea indices were significantly lower in lateral v. supine positions, respectively: MAI 15.06 (18.34) v. 32.09 (17.05); p<0.001, CAI 11.82 (11.77) v. 23.82 (14.18); p<0.001, AHI 79.46 (31.17) v. 99.47 (26.33); p<0.001, OAHI 67.87 (28.25) v. 76.00 (23.21); p=0.039. Unexpectedly, the converse was seen for OAI when comparing the lateral v. supine position: 53.10 (30.64) v. 43.58 (25.83); p=0.009, respectively. Conclusion: It may be beneficial for subjects with a combination of obstructive, mixed, and central apnoeas to avoid the supine body position. In this triform phenotype, mixed apnoeas are neither purely obstructive nor purely centrally mediated. Furthermore, obstructive, mixed, and central apnoeas may be different representations of a single respiratory abnormality.
Background. Obstructive sleep apnoea is commonly aggravated by the supine body position. e impact of body position on the severity
of mixed and central sleep apnoeas is understudied.
Objectives. To evaluate the impact of body position on obstructive, mixed and central apnoea indices in subjects presenting with this triform
of sleep apnoea during a single polysomnogram.
Methods. We retrospectively analysed 26 polysomnograms where obstructive, mixed and central apnoeas each occurred at a rate >5/hr.
Comparisons between lateral and supine body positions were made for obstructive apnoea index (OAI), mixed apnoea index (MAI), central
apnoea index (CAI), apnoea-hypopnoea index (AHI) and obstructive apnoea-hypopnoea index (OAHI).
Results. Mean (SD) apnoea indices were signicantly lower in lateral v. supine positions, respectively: MAI 15.06 (18.34) v. 32.09 (17.05);
p<0.001, CAI 11.82 (11.77) v. 23.82 (14.18); p<0.001, AHI 79.46 (31.17) v. 99.47 (26.33); p<0.001, OAHI 67.87 (28.25) v. 76.00 (23.21);
p=0.039. Unexpectedly, the converse was seen for OAI when comparing the lateral v. supine position: 53.10 (30.64) v. 43.58 (25.83); p=0.009,
respectively.
Conclusion. It may be benecial for subjects with a combination of obstructive, mixed, and central apnoeas to avoid the supine body
position. In this triform phenotype, mixed apnoeas are neither purely obstructive nor purely centrally mediated. Furthermore, obstructive,
mixed, and central apnoeas may be dierent representations of a single respiratory abnormality.
Afr J Thoracic Crit Care Med 2019;25(4):141-144. https://doi.org/10.7196/AJTCCM.2019.v25i4.024
Sleep apnoea is a breathing disorder characterised by recurrent,
partial or complete pauses in respiration.[1] Two major types of sleep
apnoea syndromes are recognised, each with its own underlying
pathophysiology. Obstructive sleep apnoea syndrome is largely the
result of upper airway instability and collapse, while central sleep
apnoea syndrome is more complex and is attributed to insucient
or absent central ventilatory drive,[2] oen secondary to cardiac or
neurological disease.[1] In overnight polysomnography, however,
regarded as the preferred laboratory test for the evaluation of sleep-
related breathing disorders,[3] three major types of sleep apnoea
are measured: obstructive, mixed and central apnoeas.[1] The
classification of mixed apnoeas remains unclear. The American
Academy of Sleep Medicine (AASM) suggests that mixed apnoeas
are part of obstructive apnoeas, despite displaying polysomnographic
(PSG) features of both central and obstructive apnoeas. Furthermore,
mixed apnoeas do not always respond well to continuous positive
airway pressure therapy, the preferred treatment method of
obstructive sleep apnoea syndrome.[4] During the treatment of such
cases, the apnoea indices of patients with predominantly mixed or
obstructive apnoeas may either decrease in severity without achieving
normalisation, or an unfavourable central apnoea response may be
inadvertently induced.[5] It is well established that body position during
sleep has an impact on the severity of obstructive sleep apnoea, where
the lateral position tends to be less severe than the supine position.
e occurrence of obstructive apnoeas can be twice as frequent in the
supine body position v. the lateral body position, an eect known as
positional dependent obstructive sleep apnoea.[6] With the exception
of Cheyne-Stokes breathing, the impact of body position on other
forms of central sleep apnoea is an area that is understudied.[7]
Objectives
is study builds on previous sleep disorder studies by examining
the impact of body position on the severity of obstructive, mixed
and central sleep apnoeas. By not limiting our study participants to
only cardiovascular-compromised patients, we were able to evaluate
various other types of central sleep apnoea in addition to Cheyne-
Stokes breathing. In addition, this study investigated whether mixed
apnoeas, which display characteristics of both obstructive and central
apnoeas, were strictly of an obstructive origin.
Methods
Study design
Subjects were eligible for this study if they were referred to the
sleep laboratory (Pretoria, South Africa) as a standard referral
for the evaluation of possible sleep-disordered breathing between
2009 and 2016. Retrospective data were collected aer a search of
the sleep laboratory’s database for polysomnograms matching our
criteria. Verbal consent was obtained aer a structured telephonic
e eects of body position on the distribution of obstructive,
mixed and central sleep apnoea
G van der Col,1 M Tech ClinTech; P R Bartel,2 PhD; P Becker,3 PhD; L T Hazelhurst,1 MSc
1 Department of Biomedical Sciences, Faculty of Science, Tshwane University of Technology, Pretoria, South Africa
2 Steve Biko Academic Hospital, Pretoria, South Africa
3 Research Unit, Faculty of Health Sciences, University of Pretoria, South Africa
Corresponding author: G van der Col (gvdcol@gmail.com)
AJTCCM VOL. 25 NO. 4 2019 141
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This open-access article is distributed under
Creative Commons licence CC-BY-NC 4.0.
142 AJTCCM VOL. 25 NO. 4 2019
RESEARCH
interview of subjects. Formal ethical approval was obtained from the
Tshwane University of Technology Faculty of Science Committee
for Research Ethics (ref. no. FCRE 2016/04/003).e primary PSG
criteria for inclusion were an obstructive apnoea index (OAI), mixed
apnoea index (MAI) and central apnoea index (CAI) of >5 per hour
of sleep and occurring within a single overnight polysomnogram.
Subjects >18 years of age were required to spend a minimum of
30 minutes in (i) each of the lateral positions and (ii) the supine body
position. Subjects who were unable to change their body position at
will (for example, during post-operative posturing or in the case of
neuromuscular disorders) were excluded from the study.
Polysomnography
Overnight polysomnography was performed either in a sleep
laboratory or in a hospital ward. No home-based sleep studies were
conducted. Subjects were not prompted to assume any specic body
position during the polysomnogram recordings. All polysomnograms
were acquired from dedicated PSG equipment (Alice PDx, Philips-
Respironics Inc., USA) and were analysed using the device’s soware
(Alice Sleepware, version 2.8.78, Philips-Respironics Inc., USA).
PSG measurements included electroencephalography (C3 and C4
placements), electrooculography, submandibular electromyography,
leg electromyography (anterior tibialis), electrocardiography, pulse
rate and oxygen saturation via pulse oximetry, nasal airflow and
snoring via nasal cannula, thoracic and abdominal respiratory eort
via inductance plethysmography belt sensors, and body position via
a built-in sensor within the recording device attached to the thorax
at mid-sternal level.
PSG data were standardised by manual reanalysis in accordance
with the criteria in the latest AASM scoring manual at the time
of the study (version 2.2).[8] Rule 1A for scoring hypopnoeas was
used. No distinction was made between obstructive hypopnoeas
and central hypopnoeas as per AASM guidelines.[8] For practical
reasons, oesophageal manometry was not performed during
polysomnography and all hypopnoeas were assumed to be
obstructive. Body positioning recording was derived from sensor
readings that dened supine, le and right body positions. e lateral
body position was recorded for le and/or right sensor readings. e
OAI was dened as the sum of obstructive apnoeas and hypopnoeas.
By this denition, the term obstructive apnoea when referring to
a specic type of sleep apnoea includes hypopnoeas. e CAI was
dened as the sum of central apnoeas and included Cheyne-Stokes
breathing. e MAI was dened as the sum of all respiratory events
that received a mixed apnoea scoring. e apnoea-hypopnoea index
(AHI) was dened as the sum of all types of sleep apnoeas and
detected in a polysomnogram.
e obstructive apnoea-hypopnoea index (OAHI) was dened
as the index derived from the cumulative values of all obstructive
apnoeas, hypopnoeas and mixed apnoeas as per AASM guidelines.[8]
Statistical analysis
Measurements from each polysomnogram included the total sleep
time, and sleep time in le, right, lateral, and supine body positions.
The total number of apnoeas, apnoeas for each apnoea type and
apnoeas in each body position was determined separately. erefore,
it was possible to determine the apnoea index of the le, right, lateral
and supine body positions, for each of the OAI, CAI, MAI, OAHI,and
AHI. ese within-subject measurements were allocated to strata
according to the apnoea index of each apnoea type respectively,
and additionally, according to the apnoea index of the respective
body positions. Statistical analysis was performed on Stata soware
(version 14, Stata Corp LLC,USA). In line with previous ndings, [9,10]
no signicant dierences in the apnoea indices between le and right
body positions were found. erefore, the le and right body position
indices were combined, and dened the lateral body position index,
which was henceforth used for comparing the severity of sleep apnoea,
in terms of the apnoea index, of any given apnoea type, between the
lateral and supine body position.
Inter-body position comparisons (lateral v. supine), of obstructive,
central and mixed apnoeas, by means of the observation vector (OAI,
CAI, MAI) was assessed using Hotelling’s paired T2-test at a 0.05 level
of signicance, while specic dierences between body positions were
assessed using Student’s paired t-tests at a 0.0167 Bonferroni adjusted
level of signicance. Furthermore, inter-body position comparisons
of the AHI and OAHI (which are linear functions of the OAI, CAI,
and MAI), were respectively assessed using Student’s paired t-tests at a
0.05 level of signicance. To compare obstructive, central, and mixed
apnoeas by body position (intra-body position comparisons), random-
eects Generalised Least Squares (GLS) regression was performed at a
0.05 level of signicance, with the index type (OAI, CAI, and MAI) as
xed eect, and participant specied as the random component with an
intercept. Linear predicted means, together with their 95% condence
intervals (CI) were reported by index over body position.
Results
A total of 31 potential candidates (1.1%) were identified from a
database of 2 802 patients, of whom 5 could not be reached for consent.
Included in the study were 26 subjects between the ages of 28 and 85
years of whom 24 were male. e demographic data of these subjects
are summarised in Table 1. Subjects were generally obese, with the
body mass index (BMI) exceeding 30 kg/m2 in 21 (81%) subjects.
Cheyne-Stokes breathing was present in 2/26 subjects.
PSG analysis determined a mean (SD) total sleep time of 473.06
(50.97) minutes. Subjects had longer sleep times in the le v. right
body position: mean (SD) 168.94 (125.21) v. 110.42 (86.59) minutes
respectively and in the lateral v. supine body position: mean (SD)
279.36 (117.13) v. 178.00 (109.63) minutes, respectively. Four subjects
completely avoided sleeping in the left position, while another
4 subjects avoided the right; however, they still met the inclusion
Table 1. Demographic data (N=26)
Variable Mean (SD) 95% CI Range
Age, years 50.22 (14.15) 44.50 - 55.94 28.90 - 85.20
BMI, kg/m234.41 (5.59) 32.15 - 36.67 26.70 - 49.40
SD = standard deviation; CI = condence interval; BMI = body mass index.
AJTCCM VOL. 25 NO. 4 2019 143
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criterion of >30 minutes of sleep in either one of the lateral positions.
e AHI was severely abnormal (>30/hour) in all 26 subjects: mean
(SD) index 88.16/hour (26.89). Mean (SD) indices for each body
position for AHI were as follows: le 79.19/hour (29.77), right 78.27/
hour (32.60), lateral 79.46/hour (31.17) and supine 99.47/hour (26.33).
Inter-positional apnoea index comparisons showed that the CAI, MAI,
AHI and OAHI were signicantly lower in the lateral than the supine
body position (Table 2). Unexpectedly, the OAI was signicantly higher
in the lateral compared to the supine body position. A Hotelling’s paired
T
2
-test with OAI + CAI + MAI as a single vector showed signicant
dierences between lateral and supine body positions (p<0.001).
Random-effects GLS regression was used to compare the intra-
positional distribution of obstructive, central and mixed apnoeas; thus,
the OAI, CAI, and MAI were compared within the lateral and supine
body positions, respectively (Table 3). While the CAI and MAI were
comparable, both were signicantly lower than the OAI irrespective of
body position. Of additional interest was to investigate whether body
position aected the severity of obstructive, central and mixed sleep
apnoea during rapid eye movement (REM) sleep; however, only one
subject met all the inclusion criteria during REM sleep and therefore
this analysis was not performed.
Discussion
The sample group in this study was representative of a severe
obstructive sleep apnoea syndrome(mean AHI 88.16/hour),
presenting mostly with obstructive apnoeas but also with a signicant
proportion of mixed and central apnoeas. is triform phenotype of
sleep apnoea may be considered a rare phenotype, with a prevalence
of less than 5%.[4] e most important nding in this study was that
while all apnoea indices were above the normal threshold in both the
supine and lateral body positions, 4/5 apnoea indices (CAI, MAI,
OAHI and AHI) were signicantly lower in the lateral body position.
e exception was the OAI, where the severity of obstructive apnoeas
was signicantly higher in the lateral compared to the supine body
position. While it is well established that obstructive sleep apnoea is
more severe in the supine position,[11] this was evident in less than
a third (27%) of the subjects in this study. For the OAHI, however,
which represented all obstructive-mediated apnoeas collectively,
sleep severity relative to body position was consistent with ndings
from other studies.[12] Considering that the OAHI, MAI and OAI are
calculated from obstructive-mediated events, it is unclear why the
OAI deviates from the MAI and the OAHI ndings with respect to
severity in supine v. lateral body positions. ree possible explanations
are proposed: (i) in subjects who present with a combination
of obstructive, mixed and central apnoeas, reflex inhibition of
respiratory eort, mediated via receptors in the mucosa of the upper
airway, may be triggered upon airway collapse associated with
obstructive apnoeas, specically while in the supine position. is
may result in an increase in the occurrence of central and mixed
apnoeas during supine sleep, as upper airway collapse is known
Table 2. Comparison of apnoea indices between lateral and supine body position (N=26)
Index Type Body Position Mean (SD)* 95% CI p-value
OAI Lateral 53.10 (30.64) 40.72 - 65.47 0.009
Supine 43.58 (25.83) 33.14 - 54.01
CAI Lateral 11.82 (11.77) 7.07 - 16.58 <0.001
Supine 23.82 (14.18) 18.09 - 29.54
MAI Lateral 15.06 (18.34) 7.65 - 22.47 <0.001
Supine 32.09 (17.05) 25.20 - 38.98
AHI Lateral 79.46 (31.17) 66.87 - 92.05 <0.001
Supine 99.47 (26.33) 88.84 - 110.11
OAHI Lateral 67.87 (28.25) 56.46 - 79.28 0.039
Supine 76.00 (23.21) 66.62 - 85.38
SD = standard deviation; CI = condence interval; OAI = obstructive apnoea index; CAI = central apnoea index; MAI = mixed apnoea index; AHI = apnoea-hypopnoea index, OAHI = obstructive apnoea-
hypopnoea index.
*Apnoea index units in events/hour.
Comparisons were made between body positions using a Student’s paired t-test with: (i) p<0.0167 considered signicantaer Bonferroni correction for OAI, CAI and MAI; (ii) p<0.05 considered signicant
for overall apnoea index (AHI or OAHI).
Table 3. Intra-position comparison of the apnoea indices (events/hour) between apnoea types (N=26)
Body Position Index Type Mean (95% CI)*
p-value
v. OAI v. CAI
Lateral
OAI 53.10 (44.75 - 61.44) - -
CAI 11.82 (3.48 - 20.17) <0.001 -
MAI 15.06 (6.71 - 23.40) <0.001 0.591
Supine
OAI 43.58 (36.02 - 51.13) - -
CAI 23.82 (16.26 - 31.37) <0.001 -
MAI 32.09 (24.53 - 39.64) 0.035 0.129
CI = condence interval; OAI = obstructive apnoea index; CAI = central apnoea index; MAI = mixed apnoea index.
*Apnoea index units in events/hour.
Random-eects Generalised Least Squares regression with p<0.05 considered signicant.
144 AJTCCM VOL. 25 NO. 4 2019
RESEARCH
to be aggravated by this body position;[13] (ii) subjects presenting
with this triform of sleep apnoea evaluated in the current study,
have been associated with altered, or increased respiratory control
instability, that may have contributed to the atypical distribution of
obstructive apnoeas;[4,14] (iii) obstructive apnoea indices vary in the
lateral position whereas are more stable in the supine position.[15]
e OAHI, which represents all obstructive-mediated apnoeas [8]
was signicantly lower in the lateral compared to the supine body
position as expected. Therefore, it could be argued that mixed
apnoeas contributed to the obstructive-mediated apnoea index
severity in relation to body position. Furthermore, mixed apnoeas
displayed characteristics of central apnoeas with respect to severity
and body position. erefore, based on patterns in severity between
supine and lateral sleeping positions, the MAI displayed both
obstructive and centrally mediated sleep apnoea characteristics.
Given the similarities between the OAHI, CAI and MAI with
respect to severity and body position, it is feasible that obstructive,
mixed and central apnoeas are of common origin, manifesting
as this triform phenotype of sleep apnoea. is hypothesis is in
keeping with that of Issa and Sullivan,[13] who suggested that in a
specic subgroup of sleep apnoea, where subjects presented with
a combination of obstructive, mixed and central apnoeas, the
occurrence of dierent types of sleep apnoea (that appear to be
body position dependent) are probably dierent representations of
a single respiratory abnormality. While this study was not restricted
to heart-failure patients and those with Cheyne-Stokes respiration
occurred only in a minority of subjects, both the MAI and CAI were
signicantly lower in the lateral v. supine body position, respectively,
which supports previous ndings.[9,16] Szollosi et al.[9] also showed that
in heart-failure patients, the CAI (central apnoeas associated with
Cheyne-Stokes breathing) was more than 50% less severe in the lateral
compared to the supine body position. We noted that in participants
presenting with the triform phenotype of sleep apnoea, a change in
body position (from supine to lateral) resulted in a reduction of ~50%
for the CAI and ~47% for the MAI.
Other studies have noted that those suering from Cheyne-Stokes
breathing and congestive heart failure prefer sleeping in the right body
position, [9,10,16] however only two subjects in this study presented with
Cheyne-Stokes breathing, therefore the nding that most subjects
preferred the le sleeping position was interesting. Subjects spent
more sleep time in the lateral body position as well, supported by
reports by Szollosi et al.[9] In contrast, Eiseman et al.[17] found that
more than half of the sleep time recorded within a sleep laboratory
environment is expected to be in the supine body position. is may
be a result of major dierences in subject selection between studies.
Both Szollosi et al.[9] and the present study included subjects where
central apnoeas were prominent PSG features (median 124 events/
hr), whereas Eiseman et al.[17] specically studied obstructive apnoeas
and central apnoeas were negligible in their study (median 2 events/
hr). is raises the question of whether subjects with PSG features
that include a signicant number of central apnoeas, compensate for
their disturbed breathing by favouring a lateral body position. Further
studies in this regard are warranted.
Conclusion
e lateral sleeping position is associated with a decrease in the severity
of obstructive-mediated (OAHI) and centrally mediated (CAI)
apnoeas in subjects who present with a combination of obstructive,
mixed and central sleep apnoeas. Furthermore, we propose that in this
specic sleep apnoea phenotype, mixed apnoeas are neither purely
obstructive nor purely central-mediated in origin. Obstructive, mixed
and central sleep apnoea may be dierent representations of a single
respiratory abnormality in patients presenting with this triform of
sleep apnoea. Further studies on the eectiveness of positional therapy
as a potential treatment option in this phenotype may be of value.
Acknowledgements. None.
Author contributions. GC co-wrote the manuscript and collected the
data. PRB co-wrote the manuscript. PRB and LH assisted with the design
and planning of the study. PB performed the statistical analysis and
also assisted with the planning of the study. PRB was the project head-
supervisor and LH co-supervised the study.
Funding. First author, GC, funded the study.
Conicts of interest. None.
1. Spriggs, WH. Essentials of polysomnography: A training guide and reference for sleep
technicians. 2nd ed. Burlington: Jones & Bartlett Learning, 2015(7-24):199-213.
2. White LH, Bradley TD. Role of nocturnal rostral uid shi in the pathogenesis of
obstructive and central sleep apnoea. J Physiol 2013; 591(5):1179-1193. https://doi.
org/10.1113/jphysiol.2012.245159
3. Berry RB, Wagner MH. Sleep Medicine Pearls. 3rd ed. Philadelphia: Elsevier/
Saunders; 2015:91.
4. Yamauchi M, Tamaki S, Yoshikawa M, et al. Dierences in breathing patterning during
wakefulness in patients with mixed apnea-dominant vs obstructive-dominant sleep
apnea. Chest 2011;140(1):54-61. https://doi.org/10.1378/chest.10-1082
5. Morgenthaler T, Gay PC, Gordon N, et al. Adaptive servoventilation versus
noninvasive positive pressure ventilation for central, mixed, and complex sleep apnea
syndromes. Sleep 2007;30(4):468-475. https://doi.org/10.1093/sleep/30.4.468
6. Eijsvogel MM, Ubbink R, Dekker J, et al. Sleep position trainer versus tennis ball
technique in positional obstructive sleep apnea syndrome. J Clin Sleep Med 2015;
11(2):139-147. https://doi.org/10.5664/jcsm.4460
7. Zaharna M, Rama A, Chan R, et al. A case of positional central sleep apnea. J Clin
Sleep Med 2013;9(3):265-268. https://doi.org/10.5664/jcsm.2496
8. Berry RB, Brooks R, Gamal do CE, et al. e AASM Manual for the Scoring of Sleep
and Associated Events: Rules, Terminology and Technical Specications, Version 2.2.
Illinois: American Academy of Sleep Medicine, 2015.
9. Szollosi I, Roebuck T, ompson B, et al. Lateral sleeping position reduces severity of
central sleep apnea/Cheyne-Stokes respiration. Sleep 2006;29(8):1045-1051. https://
doi.org/10.1093/sleep/29.8.1045
10. Leung RST, Bowman ME, Parker JD, et al. Avoidance of the le lateral decubitus
position during sleep in patients with heart failure: Relationship to cardiac size and
function. JACC 2003;41(2):227-230. https://doi.org/10.1016/S0735-1097(02)02717-1
11. Oksenberg A, Khamaysi I, Silverberg DS, et al. Association of body position with
severity of apneic events in patients with severe nonpositional obstructive sleep apnea.
Chest 2000;118(4):1018-1024. https://doi.org/10.1378/chest.118.4.1018
12. De Vries GE, Hoekema A, Do MHJ, et al. Usage of positional therapy in adults with
obstructive sleep apnea. J Clin Sleep Med 2015;11(2):131-137. https://doi.org/10.5664/
jcsm.4458
13. Issa FG, Sullivan CE. Reversal of central sleep apnea using nasal CPAP. Chest
1986;90(2):165-171. https://doi.org/10.1378/chest.90.2.165
14. Xie A, Bedekar A, Skatrud JB, et al. e heterogeneity of obstructive sleep apnea
(predominant obstructive vs pure obstructive apnea). Sleep 2011;34(6):745-750.
https://doi.org/10.5665/SLEEP.1040
15. Chou YT, Yang TM, Lin CK, et al. Pay attention to treating a subgroup of positional
obstructive sleep apnea patients. J Formos Med Assoc 2017;116(5):359- 365. https://
doi.org/10.1016/j.jfma.2016.06.007
16. Sahlin C, Svanborg E, Stenlund H, et al. Cheyne-Stokes respiration and supine
dependency. Eur Respir J 2005;25(5):829-833. https://doi.org/10.1183/09031936.05
.00107904
17. Eiseman NA, Westover MB, Ellenbogen JM, et al. e impact of body posture and
sleep stages on sleep apnea severity in adults. J Clin Sleep Med 2012; 8(6):655-666.
https://doi.org/10.5664/jcsm.2258
Accepted 15 October 2019.
... The differing clinical features and responses to treatment suggest that as much diagnostic information as possible be obtained and thus that full polysomnography be performed. In this issue of the AJTCCM, van der Colff et al. [7] is a useful demonstration of the information that can be obtained from such investigations. As the study of symptom subtypes suggests, obstructive sleep apnoea is not a homogeneous condition and detailed analysis of events in sleep related to position and sleep stage is very important in understanding mechanisms and pathophysiological phenomena contributing to clinical presentations and responses to interventions. ...
... The differing clinical features and responses to treatment suggest that as much diagnostic information as possible be obtained and thus that full polysomnography be performed. In this issue of the AJTCCM, van der Colff et al. [7] is a useful demonstration of the information that can be obtained from such investigations. As the study of symptom subtypes suggests, obstructive sleep apnoea is not a homogeneous condition and detailed analysis of events in sleep related to position and sleep stage is very important in understanding mechanisms and pathophysiological phenomena contributing to clinical presentations and responses to interventions. ...
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Positional therapy (PT) is an effective therapy in positional obstructive sleep apnea syndrome (POSAS) when used, but the compliance of PT is low. The objective of this study was to investigate whether a new kind of PT is effective and can improve compliance. 29 patients were treated with the Sleep Position Trainer (SPT), 26 patients with the Tennis Ball Technique (TBT). At baseline and 1 month polysomnography, Epworth Sleepiness Scale (ESS) and the Quebec Sleep Questionnaire (QSQ) were taken. Daily compliance was objectively measured in both groups. Both therapies prevent supine sleep position to a median of 0% (min-max: SPT 0.0% to 67%, TBT 0.0% to 38.9%), resulting in a treatment success (AHI <5) in 68.0% of the SPT and 42.9% of the TBT patients. The ESS at baseline was <10 in both groups. Sleep quality parameters as wake after sleep onset (WASO; p = 0.001) and awakenings (p = 0.006) improved more in the SPT group. Total QSQ scores (0.4±0.2, p = 0.03) and the QSQ domains nocturnal symptoms (0.7±0.2, p = 0.01) and social interactions (0.8±0.3, p = 0.02) changed in favor of the SPT group. Effective compliance (≥4 h/night + ≥5 days/week) was 75.9% for the SPT and 42.3% for the TBT users (p = 0.01). In mild POSAS with normal EES the new SPT device and the standard TBT are equally effective in reducing respiratory indices. However, compared to the TBT, sleep quality, quality of life, and compliance improved significantly more in the SPT group. © 2014 American Academy of Sleep Medicine.
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Many positional therapy (PT) strategies are available for treating positional obstructive sleep apnea (OSA). PT is primarily supplied to selected patients as a secondary treatment option when other therapies have failed. To our knowledge this is the largest study to date to assess effectiveness and long-term compliance of PT (both commercial waistband and self-made constructions, mimicking the tennis ball technique) as primary treatment in patients with different positional OSA severities. PT was used by 53 patients, of which 40 patients underwent a follow-up polygraphic evaluation under treatment after a median time interval of 12 weeks. Patients were routinely contacted regarding their clinical status and treatment compliance. PT was successful in 27 out of 40 patients (68%). Overall AHI reduced significantly from a median (interquartile range [IQR]) AHI of 14.5 (10.7-19.6) to 5.9 (3.1-8.5), p < 0.001. The commercial waistband and self-made constructions were equally effective (median (IQR) reduction in overall AHI (Δ9.6 (5.5-11.9) and Δ6.8 (3.2-11.3) respectively), p = 0.22). Short-term compliance was good as most patients used PT more than 7 hours/night (mean 7.2 ± SD 1.4) and more than 6 days/ week (mean 6.5 ± SD 1.3). However, after mean 13±5 months, 26 patients (65%) reported they no longer used PT, especially patients with moderate positional OSA (89%). On the short-term, PT using the tennis ball technique, is an easy method to treat most patients with positional OSA, showing significant reductions in AHI. Unfortunately, long-term compliance is low and close follow-up of patients on PT with regard to their compliance is necessary. © 2015 American Academy of Sleep Medicine.
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To compare the breathing instability and upper airway collapsibility between patients with pure OSA (i.e. 100% of apneas are obstructive) and patients with predominant OSA (i.e., coexisting obstructive and central apneas). A cross-sectional study with data scored by a fellow being blinded to the subjects' classification. The results were compared between the 2 groups with unpaired student t-test. Standard polysomnography technique was used to document sleep-wake state. Ventilator in pressure support mode was used to introduce hypocapnic apnea during CO(2) reserve measurement. CPAP with both positive and negative pressures was used to produce obstructive apnea during upper airway collapsibility measurement. 21 patients with OSA: 12 with coexisting central/mixed apneas and hypopneas (28% ± 6% of total), and 9 had pure OSA. The upper airway collapsibility was measured by assessing the critical closing pressure (Pcrit). Breathing stability was assessed by measuring CO(2) reserve (i.e., ΔPCO(2) [eupnea-apnea threshold]) during NREM sleep. There was no difference in Pcrit between the 2 groups (pure OSA vs. predominant OSA: 2.0 ± 0.4 vs. 2.7 ± 0.4 cm H(2)O, P = 0.27); but the CO(2) reserve was significantly smaller in predominant OSA group (1.6 ± 0.7 mm Hg) than the pure OSA group (3.8 ± 0.6 mm Hg) (P = 0.02). The present data indicate that breathing stability rather than upper airway collapsibility distinguishes OSA patients with a combination of obstructive and central events from those with pure OSA.
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To compare the severity of sleep apneic events occurring in the supine posture vs the severity of sleep apneic events occurring in the lateral posture in patients with severe obstructive sleep apnea (OSA). A retrospective analysis of apneic event variables in a group of 30 OSA patients who underwent a complete polysomnographic evaluation in our sleep disorders unit. Thirty patients with severe OSA (respiratory disturbance index [RDI] = 70.1+/-18.2) who were nonpositional patients (NPP), ie, in whom the ratio of the supine RDI to the lateral RDI is < 2 (supine RDI = 85.7+/-11.7, lateral RDI = 64.8+/-17.3), and who had > or =30 apneic events in the lateral position and 30 apneic events in the supine position during sleep stage 2 were included in the study. For the 30 apneic events in each body position, the following variables were evaluated: apnea duration (ApDur), minimum desaturation (MinDes), Delta desaturation (Delta-Des), duration of arousal (DurArous), maximum snoring loudness (MaxSL), and Delta heart rate (Delta-HR). In addition, three other variables assessed as a ratio of ApDur (Rate-D = Delta-Des/ApDur, R-HR =Delta-HR/ApDur, and R-Arous = DurArous/ApDur) were also calculated. For all variables evaluated, apneic events occurring in the supine posture were significantly more severe than those apneic events occurring in the lateral posture during sleep stage 2. ApDur of both body postures correlated significantly with DurArous, Delta-HR, and MaxSL, but not with Delta-Des and MinDes. ApDur correlated linearly with DurArous for both postures. The slopes of the two regression lines were similar (p = 0.578) but the regression line intercept for the supine apneas was significantly higher than that of lateral apneas (p<0.0001). In addition, the average number of supine apneic events that did not end with an arousal was smaller than the average number of lateral apneic events not ending with an arousal (4.4+/-6.0 vs. 10.5+/-6.7, respectively; p< 0.0001). Also, only 4 of 900 (0.44%) apneic events analyzed in the lateral posture ended with an awakening (> 15 s), whereas in the supine posture, there were 37 (4.1%) such events (p<0.001). These results show that even in patients with severe OSA who have a high number of apneic events in the supine and lateral posture, the apneic events occurring in the supine position are more severe than those occurring while sleeping in the lateral position. Thus, it is not only the number of apneic events that worsen in the supine sleep position but, probably no less important, the nature of the apneic events themselves.