The Truth About Snoring

The Truth about Snoring

Randy ClareRespiratory Diagnostics

2017

The Truth about SnoringSDB, Flow Limitation, OSAS

©2017 CareFusion Corporation or one of its affiliates. All rights reserved. CareFusion and the CareFusion logo are trademarks or registered trademarks of CareFusion Corporation or one of its affiliates.

SNORING ETIOLOGY


Snoring is…

• Snoring is noisy breathing during sleep. It is a common problem among all ages and both genders, and it affects approximately 90 million American adults — 37 million on a regular basis. Snoring may occur nightly or intermittently.

• While you sleep, the muscles of your throat relax, your tongue falls backward, and your throat becomes narrow and "floppy." As you breathe, the walls of the throat begin to vibrate - generally when you breathe in, but also, to a lesser extent, when you breathe out. These vibrations lead to the characteristic sound of snoring. The narrower your airway becomes, the greater the vibration and the louder your snoring.

• https://sleepfoundation.org/sleep-disorders-problems/other-sleep-disorders/snoring


http://sleepdisorders.sleepfoundation.org/chapter-8-variants/snoring/

SNORING, APNEA HYPOPNEA INDEX AND SLEEP DISORDERED BREATHING

Prolonged partial upper airway obstruction during sleep - an underdiagnosed phenotype of sleep-disordered breathing. Eur Clin Respir J. 2016 Sep 6;3:31806.


https://www.ncbi.nlm.nih.gov/pubmed/27608271




Apnea Hypopnea Index (AHI)

• Apnea Hypopnea Index (AHI) has been criticized for 30 years for oversimplification of Sleep Disordered Breathing (SDB). Prolonged upper airway obstruction or increased respiratory resistance (IRR) without significant hypopnea or desaturation is not considered.


• Prolonged partial upper airway obstruction during sleep - an underdiagnosed phenotype of sleep-disordered breathing. Eur Clin Respir J. 2016 Sep 6;3:31806.


Partial Upper Airway Obstruction

• Partial upper airway obstruction is underrepresented in the literature for many reasons.◦ there is no consensus of its detection, quantification or clinical impact. ◦ episodes of partial upper airway obstruction are usually prolonged,

typically for several minutes, and the severity of which cannot be defined on an event basis [as is done with AHI or respiratory disturbance index (RDI)]. • Since patients with prolonged partial upper airway obstruction may have low

AHI, it is commonly interpreted as mild sleep apnea, not warranting treatment.

◦ partial upper airway obstruction is associated with increased partial pressure of carbon dioxide (CO2), which is rarely measured in the context of a sleep study.

◦ part of the ignorance can be attributed to the fact that arousals during partial obstruction are not as frequent as they are during repetitive episodes of sleep apnea







Increased risk of High Blood Pressure• It is known that prolonged partial upper airway

obstruction may result in daytime symptoms and increase the risk of developing high blood pressure by 42% even if AHI remains normal.

• Partial upper airway obstruction is the most common form of SDB in females.







• There is an urgent need to recognize partial obstruction as a treatable form of SDB in order to understand why certain patients with low AHI may still suffer from symptoms and benefit from appropriate intervention.




Pediatrics

• Particularly in the clinical PSG of children, prolonged partial obstruction is often detected by surface electromyography (EMG) of the diaphragm and intercostal muscles, which seems to reflect changes in respiratory effort




Scoring the Snore Signal

• Prolonged partial obstruction is usually associated with sustained crescendo snoring. Using a snoring signal to assess prolonged partial obstruction is, however, problematic, since there is no means to differentiate between benign snoring and snoring associated with marked partial obstruction.

• More research needs to be done




Diagnostic tools

• In clinical practice, PSG is not needed to detect partial upper airway obstruction.

• Periods longer than hypopnea (minimum 1–3 min) are used as indicative of sustained upper airway resistance.

• Prolonged partial obstruction is usually associated with sustained crescendo snoring. Combining these two key factors, measuring the flow limitation with nasal prongs and using snoring signal, together gives a reliable marker of prolonged partial obstruction




Key Features of Prolonged Airway ObstructionDefinition Criteria - Prolonged flow limitation for more that 20-30% of TIB or TST

Crescendo SnoringCO2 increase during sleep >6kpaAbsence or repetative arousals

Diagnostic Findings- Sustained Flow limitation in nasal prongs

Increased respiratory effort (Emfit Mattress signal, inductive plethysmography, esophageal pressure)Crescendo Snoring

Population At Risk ChildrenFemalesPostmenopausal WomenPatients with symptoms of SDB but with low AHIPatients on antipsychotic therapy gaining weight

Symptoms Fatigue>sleepinessDepressive symptomsMorning headacheDecreased quality of lifeSimilar comorbidity as in SDB with high AHI

Treatment options CPAPMandibular advancement devices (MAD) in supine position dependent partial obstructionSurgery unlikely to work

AHI=apnea hypopnea index, CPAP= continuous positive airway pressure, CO2= carbon dioxide, SDB= sleep disordered breathing, TIB= time in bed, TST= total sleep timeProlonged partial upper airway obstruction during sleep - an underdiagnosed phenotype of sleep-disordered breathing. Eur Clin Respir J. 2016 Sep 6;3:31806.






FROM THE LITERATURE


• Comparing 233 age- and body mass index (BMI)-matched male–female pairs with suspected OSAS, prolonged partial upper airway obstruction was the most common single breathing abnormality, accounting for half of all observed breathing abnormalities in women compared to only one third in men

CPAP adherence and partial upper airway obstruction during sleep.Anttalainen U, Saaresranta T, Kalleinen N, Aittokallio J, Vahlberg T, Polo OSleep Breath. 2007 Sep; 11(3):171-6.


• From 157 consecutive patients referred to full PSG 29.9% presented with OSA, whereas 10.8% had prolonged partial obstruction with normal AHI

Emfit movement sensor in evaluating nocturnal breathing.Tenhunen M, Elomaa E, Sistonen H, Rauhala E, Himanen SLRespir Physiol Neurobiol. 2013 Jun 15; 187(2):183-9.


• The proportion of females was higher in patients with prolonged partial obstruction as compared with OSA patients (47 and 17% females, respectively). In healthy postmenopausal women, the prevalence of partial upper airway obstruction was 10 times higher (17.7%) compared with that of frank OSA (1.6%)

Breathing during sleep in menopause: a randomized, controlled, crossover trial with estrogen therapy. Polo-Kantola P, Rauhala E, Helenius H, Erkkola R, Irjala K, Polo O Obstet Gynecol. 2003 Jul; 102(1):68-75


• In a clinical sample of pre- and postmenopausal women, the prevalence of SDB was 79.4 and 86.2%, respectively

Impact of menopause on the manifestation and severity of sleep-disordered breathing.Anttalainen U, Saaresranta T, Aittokallio J, Kalleinen N, Vahlberg T, Virtanen I, Polo O Acta Obstet Gynecol Scand. 2006; 85(11):1381-8


• The prevalence of frank obstructive sleep apnea did not differ, whereas partial upper airway obstruction was more prevalent in postmenopausal (66.1%) than in premenopausal (50.9%) women

Impact of menopause on the manifestation and severity of sleep-disordered breathing.Anttalainen U, Saaresranta T, Aittokallio J, Kalleinen N, Vahlberg T, Virtanen I, Polo O Acta Obstet Gynecol Scand. 2006; 85(11):1381-8


• In a retrospective study of 240 women no difference was observed in terms of sleepiness or other symptoms between women with partial upper airway obstruction or classical obstructive sleep apnea

Women with partial upper airway obstruction are not less sleepy than those with obstructive sleep apnea.Anttalainen U, Polo O, Vahlberg T, Saaresranta TSleep Breath. 2013 May; 17(2):873-6.


• Sleep laboratory patients with prolonged partial obstruction had decreased life quality score as compared with OSA patients

Emfit movement sensor in evaluating nocturnal breathing.Tenhunen M, Elomaa E, Sistonen H, Rauhala E, Himanen SLRespir Physiol Neurobiol. 2013 Jun 15; 187(2):183-9.


• Micrognathia was more common in women with partial upper airway obstruction compared to those with OSA

Women with partial upper airway obstruction are not less sleepy than those with obstructive sleep apnea.Anttalainen U, Polo O, Vahlberg T, Saaresranta TSleep Breath. 2013 May; 17(2):873-6.


Micrognathism,called micrognathia, strawberry chin, hypognathia[1] or hypogthathism, is a condition where the jaw is undersized. It is also sometimes called "Mandibular hypoplasia". It is common in infants, but is usually self-corrected during growth, due to the jaws' increasing in size. It may be a cause of abnormal tooth alignment and in severe cases can hamper feeding.[2]

It can also, both in adults and children, make intubation difficult, either during anesthesia or in emergency situations.


http://www.angelakeen.com/portfolio-items/chins

https://en.wikipedia.org/wiki/Micrognathism#cite_note-pmid7883869-1

https://en.wikipedia.org/wiki/Jaw

https://en.wikipedia.org/wiki/Human_mandible

https://en.wikipedia.org/wiki/Micrognathism#cite_note-HongBrake2012-2

https://en.wikipedia.org/wiki/Intubation

ObesityPrevalence of OSAS increases with age and obesity. In a study of 233 age- and BMI-matched male–female pairs, classical sleep apnea increased with increasing BMI only in men, whereas partial obstruction increased with moderate to morbid obesity in both genders after the age of 65 years


• Episodes of prolonged partial upper airway obstruction are associated with increased intrathoracic pressure variation and increased CO2 level, indicating increased respiratory efforts and respiratory workload. Partial upper airway obstruction may be one important factor in the development of hypercapnic respiratory failure.


• hypertension might be a consequence of untreated partial obstruction.

• In a study of 133 women and 122 men, reimbursed medication for hypertension was used three times more often in patients with partial obstruction compared with those with frank OSA

Reimbursed drugs in patients with sleep-disordered breathing: A static-charge-sensitive bed study.Anttalainen U, Polo O, Vahlberg T, Saaresranta TSleep Med. 2010 Jan; 11(1):49-55.


SDB in Pregnancy

• In women with pre-eclampsia, SDB typically manifests as flow limitation with increased nocturnal CO2but low AHI and an increased number of oxygen desaturations especially during rapid eye movement sleep (REM).

• Blood pressure responses to episodes of obstructive apnea are augmented in normal pregnancy and further in preeclampsia.

• The increased sympathetic activity during the third trimester contributes to the increased prevalence of OSA, which in turn probably further augments sympathetic tone and predisposes to preeclampsia (67)

Review Sleep disordered breathing and pregnancy.Edwards N, Middleton PG, Blyton DM, Sullivan CEThorax. 2002 Jun; 57(6):555-8.


https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5015642/#CIT0067

Depression

• Depression is more frequently observed in female OSA patients compared with male patients which may at least partly explain the higher degree of daytime fatigue and sleepiness in female patients with low degree of OSA. Sforza et al. reported that women with OSA had five-fold increased risk of having depression compared to men (11.9% vs. 2.7%)

Mood disorders in healthy elderly with obstructive sleep apnea: a gender effect.Sforza E, Saint Martin M, Barthélémy JC, Roche FSleep Med. 2016 Mar; 19():57-62.


Summary

• Particularly in women, the upper airway obstruction often manifests as non-countable non-apneic respiratory events (snoring, flow limitation or partial upper airway obstruction). Failure to recognize prolonged partial obstruction in sleep studies may lead to under recognition of SDB especially in women. Partial obstruction, even in the absence of episodes of apnea, may cause clinically significant symptoms. Patients with symptomatic partial upper airway obstruction respond and adhere to nasal CPAP therapy at least as well as those with ‘conventional’ OSAS. The scarce available data suggest that despite less severe OSA in females, the consequences of OSA might not be less severe. Therefore, identifying the phenotype of partial upper airway obstruction during sleep may lead to timely and appropriate therapy especially in female patients and might also reduce lost work days among them.


DIAGNOSIS, SNORING AND PARTIAL UPPER AIRWAY OBSTRUCTION


Snoring detection according AASM (rev. 2012)

The 2007 AASM scoring manual did not recommend a sensor for snoring.

There is a paucity of published data on snoring sensors. Optimal visualization of snoring requires a high frequency filter

setting that permits recording/display of rapid oscillations (100 Hz recommended in the 2007 scoring

manual). Based on limited information, the task force recommends

several sensors as options for snore detection: the unfiltered nasal pressure signal, piezoelectric sensors to detect vibration, or acoustic sensors (e.g., microphone) to record sound.


The assessment of snoring

No "gold standard" available for subjective or objective measurement (and scoring) of snoring

A belief …


How to measure snoring reliably?


Arnardottir et al, J Sleep Res (2015)

• 10 study subjects with reported snoring• Five (5) male and five (5) female (all Caucasian)• Mean age: 53 years (range 27–80 years)• Mean BMI: 29 kg m2 (range 25–32 kg m2)• Mean AHI: 10.3 (range 0.3–53.5)• Mean ODI: 9.7 (range 0.2–53.3).

• Subjects snored (single snores) on average 362 times per hour for the duration of the whole sleep study (range 9–689 times) based on manual scoring of snore events using the chest audio.

Study Population


The assessment of snoring

The reality …


Snoring Signal measured from Cannula and Digital Audio with Nox T3


Fundamental frequency assessed by spectral analysis (vibration frequency of the airway)

•

Information according: Arnardottir et al, J Sleep Res (2015)

Cannula and piezo microphone – a major limitation for snoring signal information & analysis

Sensors as cannula and piezo are usually sampled at 200 Hz Measure (theoretically best case) and restore only signal frequencies up to

100 Hz Signals with frequencies above 100 Hz cannot be reliably detected



Sensitivity and PPV for Snoring Detection


Nox Systems – some microphone background (1)• Microphones measure pressure (mPa) and derive

dB values:◦ can only be compared when distance is the same / known

(otherwise a given value in dB is „useless“ – at least cannot be compared)

◦ standard distance for dB values of household appliances: 1 meter (usually dBa values given)

• Nox build-in microphones (Nox T3 and Nox A1) are calibrated towards industrial audiometers same results would appear for Nox microphone and industrial audiometer if used at the same distance from the noise source


Nox Systems – some microphone background (2)• The sound pressure level decreases by 6 dB, each time

the distance from the point source is doubled (inverse‐square law in acoustics)

◦ If we measured at ~25 cm from the source our dB value is +12 dB compared to a usual standard distance of 1 meter

• More information for sound characteristic can be found:◦ http://www.sengpielaudio.com/calculator-SoundAndDistance.htm◦ https://www.osha.gov/dts/osta/otm/new_noise/index.pdf

Sound pressure in a free field

Figure Source : https://www.osha.gov/dts/osta/otm/new_noise/index.pdf©2017 CareFusion Corporation or one of its affiliates. All rights reserved. CareFusion and the CareFusion logo

are trademarks or registered trademarks of CareFusion Corporation or one of its affiliates.

http://www.sengpielaudio.com/calculator-SoundAndDistance.htm

https://www.osha.gov/dts/osta/otm/new_noise/index.pdf

Microphone proximity improves snoring diagnosis in Women and Pediatrics


Noxturnal Audio - Signal Traces

Audio8,000 Hz

Flow (cmH2O)200 Hz

Audio Volume Envelope (mPa)100 Hz

Audio Volume Envelope (dB) 100 HzdBc weighted


The distribution of all eventsscored manually by listening to snore (n = 25,268) for the whole night recordings from the chest microphone showing

• the dB(C) range• the dB(A) range.


Snoring and Snoring Signal Information


• The dBa weighting curve is simulating the frequency response of the human ear and the measure is therefore frequency dependent.

• The dBc weighting curve is measuring the actual sound power independent of the frequency.

• Using dBa could for example result in a men snoring at 60 Hz center frequency being measured approximately 6 dB lower than a woman snoring with the same power at 120 Hz center frequency.

Audio dBc versus dBa

Figure Source Wikipedia: https://en.wikipedia.org/wiki/A-weighting


1. Arnardottir et al, J Sleep Res (2015): „ The dB(A) weighting, which attempts to mimic the human ear response to sound, for example for studies on noise annoyance, attenuates sounds strongly in this frequency range (3–50 dB attenuation in the audible range from 20 to 500 Hz), …” … “Therefore, the authors consider dB(A) weighting to be an inappropriate measure for assessment of objective snore characteristics … “

2. Assessment of vibrations should be independent from human ear sensitivity :◦ Amatoury et al., J Appl Physiol (2006): Snoring-related energy

transmission to the carotid artery in rabbits◦ Curry et al., The anatomical Record Part (2005): Evidence for

Frequency-Dependent Arterial Damage in Vibrated Rat Tails

The choice between dBc / dBa


References







Questions

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The Truth About Snoring

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