Sleep Disordered Breathing (SDB)

The detrimental effects of sleep disturbance produced by abnormal breathing patterns have been extensively studies in recent times and are called as Sleep disordered breathing (SDB).

SDB constitutes a number of the major part of sleep disorders seen by sleep physicians’ world over.

With growth of Obesity, Hypertension, Diabetes, & use of Medicines, Otolaryngologists & Sleep clinicians are witnessing a large increase in such patients.

IMPACT

SDB and along with its effects is a very significant problem in the society as it can lead to

Road traffic accidents

Lower productivity at school and work

Morbidity-Impaired immune function, HTN, insulin resistance, stroke, pulm HTN, poor asthma control, ventricular arrhythmias and sudden death

Neuro-cognitive and mood dysfunction

Impaired quality of life

Impaired performance in surgical skills, anesthesia administration, intubations and ECG interpretation

EPIDEMIOLOGY

Recent data suggests approximately 5% of population suffer from SDB 12-15 million adult American have SDB. In Indian scenario polyssomnography proven cases of SDB is around 3.57% (Sharma et al)

SEX

Males> Females

Severe OSA male to female is 8:1, moderate OSA 3:1

Sex difference reduces after menopause

The reasons for sex predilection are not clear, possibly due to

Body fat distribution

Craniofacial differences

Female hormone

RISKFACTORS & ASSOCIATED MEDICAL CONDITIONS

Obesity

Cardiovascular disease

Increased risk of HTN

Cerebrovascular disease This has unclear but growing evidence, studies reveal that the odds ratios of having a CV stroke are high but this was not significant not after adjusting for age and BMI

Metabolic syndrome This is a term used for features related to Waist circumference, Triglycerides, Glucose level, BP, Insulin resistance

DEFINITIONS

Snoring Loud upper airway breathing sounds in sleep without episodes of apnea or hypoventilation

Apnoea Cessation of airflow at nostrils and mouth for at least 10 seconds regardless of oxygen saturation

Sleep Apnea syndrome

30 or more apnoeic episodes during 7 hrs sleep

Apnea index =/>5

Obstructive sleep apnea

Cessation of airflow in presence of continued respiratory effort

Breath holding spells

Central sleep apnea Cessation of airflow with cessation of all respiratory effort

Mixed Apnea Begins as a central type of apnea followed by increasingly forceful respiratory efforts till airflow clears

UARS Increased inspiratory effort with frequent arousals but no apnea or hypopnea

PATHOPHYSIOLOGY OF SLEEP DISORDERED BREATHING

The primary cause of SDB is collapse of the upper airway during sleep. The mechanism for this is multi-factorial, which is mainly due to interdependence of anatomical vulnerability with physiologic mechanism of ventilation.

Local Factors

The size of lumen depends on the dilating and collapsing forces

The dilating forces include

Dilating muscle activity

Mechanical force on airway wall

Intraluminal airway pressure

Large upper airway

The collapsing forces include

Mass lesion in nasopharynx

Negative intraluminal pressure

Tissue mass

Surface adhesive forces

Increased extra luminal pressure

Craniofacial characteristics

Increased distance of hyoid from mandibular plane

Retrognathia

Increased cervical angulations

Neck and jaw posture

Neck flexion close airway, extension opens it

Opening Jaw slightly increase size of airway

Progressive opening– pharyngeal narrowing

Large tongue

Myxedema

Acromegaly

Oropharynx

Tonsillar enlargement

Macroglossia

Retrognathia

Hunters/Hurlers

High arched palate

Nasopharynx

Adenoid hypertrophy

Hypopharynx

Mass/growth

Nose

Nasal obstruction also has a role in causing severity of OSA

Reduced nasal airflow affect muscle tone of upper airway

Increase mouth opening

Destabilize pharyngeal airway

Reduced humidification

Causes

Nasal polyps

DNS

Rhinitis

Choanal atresia

CLINICAL FEATURES

The patients of OSA has certain characteristic night and day time complaints

Night Time

Snoring

Witnessed breath holds,Choking

Fragmented sleep

Restlessness

Dry mouth mainly due to mouth breathing

Nocturia  due to Increased abd pressure, Atrial natriuretic peptide

Esophageal reflux due to heartburn

Day time

Sleepiness

Afternoon

Meeting

Driving

Headache

Fatigue, reduced alertness

Personality changes

Irritability

Anxiety

Depression

APPROACH TO PATIENT WITH SLEEP DISORDERED BREATHING

History

Underestimate symptoms…leading questions help

RTA/Drifting across lanes/honked by drivers

Assocoated HTN/ DM asked and looked for.

Physical Findings

Obesity and BMI calculation >28 kg/sq mt

Neck circumference

Superior border of cricothyroid membrane, upright position

Cut off level of 40-43 cms highly specific in OSA

Detailed nasal / oropharyngeal assessment

Macroglossia

Uvula, soft palate – low lying/size/edema/erythema

Retrognathia

Tonsillar hypertrophy

Nose –Contributory factor

INVESTIGATION

Establish diagnosis

PSG, oximetry, multichannel home testing

Estimate level of obstruction:..

Pharyngoscopy, Radiology, manometry

Investigate for Causes / Predisposing factors/Sequelae….

Hematological Ix for Hypothyroidism, HTN, Diabetes mellitus

To establish Diagnosis

Overnight Polysomnography(PSG)…Gold Standard

Overnight Oximetry

Home multi channel  testing

PSG(POLYSOMNOGRAPHY)

Considered gold standard in diagnosis of OSA

Can differentiate central from peripheral apnea

Not ideal but best available

Breathing disturbance may vary from night to night

Does not suggest the site of obstruction

Simultaneous Recording of multiple sleep related events

Neurophysiolgical

Cardiopulmonary

Other physiological parameter over course of several hours

Parameters specified by AASM

EEG( frontal, central, occiptal)

B/L EOG

Chin EMG,Leg EMG

Airflow,Respiratory effort( chest and abdominal)

SpO2, ECG

Body position, & Video monitoring

OVERNIGHT OXYMETRY

It is a gadget sited at the end of digit with a wrist watch like device which measures oxygen saturation and pulse rates

Standard practice

4% drop in O2 saturation( resting >90%)

ODI: Oxygen desaturation index

Number of times O2 saturation falls >4% per hr

>15 suggests OSA

Advantage

Easily available and cost effecient

Good specifcity

Good +Predeictve value

Very useful if positive

Disadvantage

Poor sensitivity

Poor – pred.value

Miss subjects OSA who don’t de-saturate

NOTE

If OD!<15, but other cofactors present refer for multi-channel assessment

HOME MULTI-CHANNEL TESTING (Multi channel: nasal/oral airflow, chest & abdominal movements, Pulse oximeter)

Advantages

Better patient comfort

Cost savings

No hospital admission

Speed of analysis

Disadvantages

Sensor failure

Fewer channels

Underestimate severity as EEG not available

INVESTIGTION TO DETERMINE SITE OF OBSTRUCTION

MULLERS MANUVEUR

Patient performs reverse valsalva

Effort generates negative pressure in upper airway

Nasopharyngeal sphincter is visualized with  endoscope

Compliant tissue will collapse

Degree of collapse scored

Used as criteria for patient selection for Surgery

Not a reliable test as

Done in awake patient

And surgery based on this test is unsuccessful

Radiological Investigations

Lateral cephalometry

Very accurately taken lateral head and neck Xray

Relationship between various soft tissue and bony points measured

No study has shown significant change in normal and OSA

Not sole diagnostic procedure

CT SCAN

Greater anatomic details

Awake state so low predictive value for diagnosis of OSA

3-D scans

Easier way to assess the caliber of upper airway

Statistical correlation with severity of OSA lacking

MRI

Good anatomic definition of soft tissue

Multiplanar images

No radiation exposure

Dynamic images can also be obtained

Disadvantage

Awake patient

Scanner noise

Limited studies available

Manometry

Use of catheters in upper airway to measure pressure at various sites

Important for patients suspected of UARS

No frank apnea, but snoring and arousals in sleep

Advantage

Sleep manometry documents obstruction site

Disadvantage

Precise placement o probe

Poorly tolerated

DIAGNOSTIC CRITERIA

AHI: Number of apnea and hypopnoea averaged per hour of sleep

RDI: (respiratory disturbance index)

Number of apnea hypopnea and respiratory effort related arousal, diagnosed by EEG

AHI<5: no evidence of OSA

AHI:5-15: mild OSA

AHI:15-30: moderate OSA

AHI:>30: severe OSA

No account of desaturation index nor the length of apnea and hypopnea

TREATMENT

Depends on number of factors

Severity of disorder

What does patient want

Presence of any complication

Level of obstruction

Treatment options

Non surgical

Surgical

NON-SURGICAL

Address co-existent, predisposing conditions

Obesity

Tobacco

Sleep deprivation

Avoiding agents affecting sleep

Treat hypothyroidism

Modification of body position during sleep

Mechanical devices( positive airway pressure)

Pharmacological  therapy

MANAGE OBESITY

Documented reduction in symptom after weight reduction

Degree of improvement  no linear corelation with weight

Few may not benefit if co-existent craniofacial abnormalities

Life style modification

Dietary modification

Pharmacological

Surgical options

BODY-POSTURE MODIFICATION

Sleeping with head and trunk elevated to 30-60 degree angle to horizontal reduces OSA

Lateral decubitus is also effective in reducing episodes (sleep ball)

Pharmacological Therapy

Protriptyline

Effects not proven

Agents with uncertain limited role

Serotonin agonists

Affects the pharyngeal dilators

Busiprone used

Data insufficient

Stimulants

Amphetamines are also used but known to have CVS complication. Insufficient data

CPAP(continous positive airway pressure)

When to use?

Mild OSA with EDS/ Co-morbidities, moderate to severe OSA

Many consider it to be mainstay of OSA treatment

Mechanism

Acts as pneumatic splint

Equipment

Machine provides fixed pressure or vary pressure depending on the presence of apnoeas (Auto CPAP)

Mask is nasal or full face, kept in place by Velcro straps

Port of exhalation

Newer machine small and light so portable

Humidifier also available as an optional mode

SIDE EFFECTS

Claustrophobia

Nasal stuffiness

Skin abrasions, nasal bridge abrasions

Leaks are uncomfortable or eyes

Air swallowing if pressure more than esophageal sphincter pressure

Pulmonary baro trauma ( very rare)

Treatment Failure

COMPLIANCE WITH CPAP

By 3 years 25-40% stop using CPAP mainly due to one of possible reasons:

Treatment failure

Cost factor

Regular service and maintenance

Change of mask

Side effects

SURGICAL TREATMENT

Uuvuloplatopharyngoplasty(UPPP)

Laser assisted UP(LAUP)

Radiofrequency tissue volume reduction(RFTVR)

Genioglossus advancement

Other surgeries

UVULOPALATOPLASTY

First described by Ikematsu(1950), Fugita popularized in 1985

The Surgical principle:

Stiffen the soft palate by scarring

Increase space behind soft palate

Complications:

Severe post op pain

Hemorrhage

Laryngospasm

Polmonary edema, hypoxia

Nasal regurgitation

Swallowing & voice problems

Not satisfied post surgery

FACTS

75-95% short term success

Long term –45%

Modification: Preserve uvula

LAUP(LASER ASSISTED UVULOPLASTY)

Described by Kamami in France in 1993

Stiffen the soft palate

Prevent palatal flutter

Surgery

Local anesthesia on soft palate

B/L vertical incision in soft palate followed by partial vaporization of uvula with CO2 Laser

Various modification done

Complications

Low

Globus like symptom common

Post operative pain

RFTVR(RADIO-FREQUENCY TISSUE VOLUME REDUCTION THERAPY

Similar to diathermy

Lower temperature, lower current and voltage

Thermal injury to specific submucosal sites in soft palate causing fibrosis and contraction

Advantage

Day care, LA

Less post operative pain

Significant improvement reported

Good for multi level obstruction

Low relapse rate

OTHER OCCASIONAL SURGICAL PROCEDURE

Palatal: Z-pharyngoplasty, palatal implants

Tongue base

RFTVR

Laser midline glossectomy

Tongue suspension suture

Hypoglossal nerve stimulation

Epiglottis

epiglottectomy

Temporary tracheostomy

Hyoid myotomy and suspension

Maxillomandibular osteotomy and advancement

ORAL APPLIANCES

Two basic types of appliances used

Mandibular advancement devices– popular

Positioning the lower jaw and tongue downward and forward.

The airway passage is increased

Comfortable

More effective,

Tongue repositioners.

pulling only the tongue forward and not the entire lower jaw.

teeth, jaw muscles and joints are less affected.

Less studied

A period of consistent nightly wear is required

Patient motivation and cooperation essential

Author Name:
Dr Prasun Mishra
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