SLEEP DISORDERED BREATHING(SDB)


Introduction:

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 an unclear but growing evidence
Studies reveal that the odds ratio 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



DEFINATIONS

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 by :
• Reduced nasal airflow affect muscle tone of upper airway
• Increase mouth opening
o 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 symptoms constitutes of
o Sleepiness
 Afternoon
 Meeting
 Driving
o Headache
o Fatigue, reduced alertness
o Personality changes
 Irritability
 Anxiety
 Depression








APPROACH TO PATIENT WITH SLEEP DISORDERED BREATHIN

History

Detailed history
Underestimate symptoms…leading questions help
RTA/Drifting across lanes/honked by drivers
Assocoated HTN/ DM asked and looked for.

Physical Findings

o Obesity and
 BMI calculation
• >28 kg/sq mt
o Neck circumference
 Superior border of cricothyroid membrane, upright position
Cut off level of 40-43 cms highly specific in OSA




Detailed nasal/ oropharyngeal assessment

o Macroglossia
o Uvula, soft palate – low lying/size/edema/erythema
o Retrognathia
o Tonsillar hypertrophy
o Nose –Contributory factor



INVESTIGATION


o Establish diagnosis…
o PSG, oximetry, multichannel home testing
o Estimate level of obstruction:..
o Pharyngoscopy, Radiology, manometry
o Investigate for Causes / Predisposing factors/Sequelae….
o 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

o Simultaneous Recording of multiple sleep related events
o Neurophysiolgical
o Cardiopulmonary
o Other physiological parameter over course of several hours

o Parameters specified by AASM
o EEG( frontal, central, occiptal)
o B/L EOG,
o Chin EMG,Leg EMG
o Airflow,Respiratory effort( chest and abdominal)
o SpO2, ECG
o Body position, & Video monitoring
OVERNIGHT OXYMETRY
o It is a gadget sited at the end of digit with a wrist watch like device which measures oxygen saturation and pulse rates

o Standard practice:
o 4% drop in O2 saturation( resting >90%)
o ODI: Oxygen desaturation index
 Number of times O2 saturation falls >4% per hr
 >15 suggests OSA
o Advantage:
o Easily available and cost effecient
o Good specifcity
o Good +Predeictve value
o Very useful if positive

o Disadvantage
o Poor sensitivity
o Poor – pred.value
o Miss subjects OSA who don’t de-saturate

o NOTE:
o 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)


o Disadvantages
– Sensor failure
– Fewer channels
– Underestimate severity as EEG not available

o Advantages
– Better patient comfort
– Cost savings
– No hospital admission
– Speed of analysis


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

Soft palate Lower pharynx
3 or 4 No ideal
3 or 4 1 or 2 Sub optimal
<3 >2 Not suitable

1=minimal collapse
2=reduced area by 50%
3=reduced area by 75%
4=complete obliteration






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
Principle
– 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


Principle
– 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


For treatment and guidance
Dr (major) Prasun Mishra
Pune
09881676449