Management of OSA Flashcards
Describe what causes OSA
OSA occurs when airways collapse.
Airway obstruction usually occurs in oropharynx i.e. is retropalatal and retroglossal.
OSA is caused by:
- Factors that Increase Compliance of Tube
- a reduction in transmural pressure
Describe the factors that increase the compliance of the tube
-
Reduction in Longitudinal Tension of the Tube
- Reduction of lung volume (e.g., due to central obesity)
-
Suppression of Pharyngeal Muscle Activation (Reduces Airway Tone)
- Alcohol, sleep deprivation, anaesthesia
- note that some people only have it with alcohol consumption
- Alcohol, sleep deprivation, anaesthesia
Describe the factors that result in reduced transmural pressure
A Reduction in Transmural Pressure (P tm) is Due to
A. Increase in Surrounding Tissue Pressure (P tissue) or
B. Decrease in Intraluminal Pressure (P lumen)
Increase in Surrounding Tissue Pressure
- Rigid box too small: bordered by mandible (anterior and lateral walls) and cervical spine (posterior wall)
- neck and jaw posture also influence the size of the box
- neck flexion closes airway
- neck extension opens it
- jaw opens slightly : increases size of box
- jaw opens wide: decreases size of box by moving genu of mandible posteriorly
Too Many Other Things in the Box
- Soft palate (muscle and fat)
- Tongue (muscles and fat)
- Muscles (posterior constrictors and oropharyngeal muscles)
- Tonsils (lymphoid tissue)
- Adipose tissue (parapharyngeal fat pads)
-
- Note: Edema (e.g. due to inflammation and tissue swelling) resulting from OSA can therefore make OSA worse
Position of Tongue and Soft Palate
- Affected by gravity and surface tension
- Mouth opening - decreases mucosal surface tension, thus freeing mucosal attachment of tongue and soft palate, allowing tongue and soft palate to move posteriorly
- Sleeping supine causes gravity to pull the tongue and soft palate posteriorly
Describe the factors resulting in a decrease in intraluminal pressure
- Nasal obstruction
- Airway obstruction due to
- Loss of energy due to work done in overcoming flow resistance, and
- The Bernoulli effect
- Conversion of energy from static to kinetic due to increased velocity of airflow when the lumen size decreases
Describe the relevant questions to ask regarding the history of presenting illness
- Symptoms of OSA
- Are due to the direct effect of airway closure and narrowing
- Indirect effects
- Resulting from the indirect effects
Describe the sources of OSA symptoms
- direct effects
- indirect effects
Describe symptoms due to direct effects
- Snoring
- Apnoea
- Sore throat
(Wheezing due to obstruction or soft tissue vibration)
Describe symptoms due to indirect effects
- Choking and gasping arousals
- Nocturnal palpitations
- Nocturnal hypertension
- Nocturia
- Poor sleep
- Nocturnal GORD
What are the results of the indirect effects?
- Unrefreshing sleep
- Daytime sleepiness (may result in problems with memory and concentration, involuntary naps, poor job performance, MVA, work-related accidents)
- Mood disorders
- Morning headache
- Family discord
List some questions to ask regarding duration and severity of symptoms
- For how long have they had the symptoms? ^[many put up with symptoms]
- Why are they seeking intervention now?
- Is there any other association (e.g., weight gain) with symptom onset or an increase in symptom severity?
Which questionnaire is used to assess the severity of daytime sleepiness?
Epworth sleepiness scale.
A score of 11 or more indicates a sleeping disorder such as obstructive sleep apnoea.
A very high score such as 17 can indicate narcolepsy.
Which diseases are important to inquire about in the past medical history?
- Those that can exacerbate OSA
- Those that can increase the adverse health risks of OSA
- Those that may be exacerbated by OSA
- Those that interfere with treatment
- Those that may result in other forms of sleep-disordered breathing (e.g., central sleep apnea resulting from cardiac failure)
- Those that may mimic symptoms of OSA (e.g., choking arousals from GORD), or by causing similar daytime symptoms)
List conditions that can exacerbate OSA
- Anything that causes weight gain (e.g., hypothyroidism, or conditions that reduce mobility and ability to exercise), or requires medications that cause weight gain (e.g., corticosteroids, some anti-epileptics, some anti-psychotics)
- Hypothyroidism also causes myxoedema which can exacerbate OSA. It also results in daytime symptoms that can be similar to those resulting from OSA.
- Anything that causes nasal obstruction (e.g., hayfever)
- Anything that results in craniofacial abnormality
List conditions that can increase adverse risks of OSA
- Conditions that result in nocturnal hypoventilation can cause worse overnight O2 desaturation and increase the risk of pulmonary hypertension (e.g., COPD, Obesity Hypoventilation Syndrome)
- Hypertension, diabetes, elevated cholesterol increase the cardiovascular risks associated with OSA
List conditions exacerbated by OSA
- Afib
- Hypertension
- Obesity
- GORD
- CVA
- IHD and cardiac failure
- Depression (this may, however, also cause daytime sleepiness)
Describe some medications that can exacerbate OSA
- Attention to those that can exacerbate OSA (e.g., opioids)
- Opioids can also result in central sleep apnoea and daytime sleepiness
Are allergies relevant? Explain why/why not
- Especially to tape or latex
- This will affect what we do later during sleep studies
Describe details of family history that might be relevant
Genetics can play a role in OSA e.g. craniofacial structure.
- OSA
- Other sleep conditions e.g. narcolepsy
- Cardiovascular or cerebrovascular disease
Describe relevant details in the social history
- SMOKING – WILL INCREASE HEALTH RISKS OF OSA
- ALCOHOL – WILL EXACERBATE OSA
- OTHER ILLICIT DRUGS – DISTURB SLEEP IN MANY DIFFERENT WAYS
- OCCUPATION – DOES THIS INVOLVE LONG-DISTANCE DRIVING, DOES THE PATIENT REQUIRE A COMMERCIAL DRIVER’S LICENSE FOR WORK, DOES THE PERSON WORK SHIFTS, NIGHT DUTIES?
What things should you look out for in the physical examination?
- Neck Circumference
- BMI
- Craniofacial structure e.g. retrognathia and dental overjet
- Modified Mallampati score (to check for macroglossia/small oral cavity)
- Tonsillar grade
- Nasal patency
- Blood pressure
- +/- fiber-optic nasopharyngoscopy
List anatomical features that can increase OSA risk
- high moddified mallampati score
- tonsillar hypertrophy
- tonsillar grades
Why are diagnostic sleep studies conducted?
- confirm the presence of OSA
- assess the severity of OSA
What are the guidelines regarding GPs and sleep apnoea?
General practitioners can directly refer eligible patients for diagnostic home-based (unattended) or laboratory-based sleep studies for obstructive sleep apnea when an approved assessment tool has been used.
General practitioners can also continue to refer eligible patients with suspected sleep disorders to qualified adult sleep medicine practitioners and consultant respiratory physicians for further investigation.
General practitioners who want to directly refer patients for a diagnostic home or laboratory-based sleep study to confirm a diagnosis of sleep apnea will need to determine a patient’s eligibility by using approved assessment tools and meeting the criteria below.
Which tools can be used to assess a patient with suspected OSA?
Either one of:
- STOP-BANG score ≥ 3
- OSA-50 score ≥ 5
STOP-BANG
Risk of moderate to severe OSA
STOP-BANG score
- 5-8 - high
- 3-4 - intermediate
- 0-2 - low
OSA-50
OSA-50 score of 5 or more = high risk for OSA
Describe sleep studies
- Polysomnography, also known as an overnight diagnostic sleep study
Severity of OSA
AHI = Apnea Hypopnea Index
- Normal = < 5 per hour
- Mild = 5 - 15 per hour
- Moderate = 15 - 30 per hour
- Severe = ≥ 30 per hour
- note that there is a diversity of outcomes in the severe category – impacts prognosis
-
Severity correlates with the risk of morbidity and mortality from OSA
Severity affects treatment options
What are the treatment options and aims?
Treatment
- Aim of treatment
- Reduce day and night-time symptoms
- Reduce the risk of adverse health consequences from OSA
Treatment
- Lifestyle modifications to lose weight and increase fitness
- Avoid precipitants to upper airway obstruction (alcohol)
- Treat nasal obstruction – avoidance of allergens, normal saline washes/irrigation, medication and surgery
- Sleep Posture Training
- Mandibular advancement splint / Tongue retaining devices
- EPAP devices (e.g., Bongo Rx, ULTepap, Optipillows)
- CPAP
- Surgery (bariatric, soft tissue surgery - tonsils, soft palate, tongue - mandibular advancement, implantation of a hypoglossal nerve stimulator (Inspire)) - preferred for younger patients to avoid life-long device use
- Supplemental Oxygen (last resort for OSA if refuses all other treatment and overnight O2 saturation low)
- High flow Oxygen
Describe CPAP
CPAP works by increasing Intraluminal pressure (P lumen)
Describe mandibular advancement splint
MAS works by advancing mandible forward, therefore increasing size of rigid box and reducing tissue pressure (P tissue)
Describe other treatment options
How EPAP Devices Work
During inspiration, the valve opens to allow for unobstructed airflow. During expiration, the valve closes, restricting airflow to create EPAP and maintain pressure in the airway through the start of the next inspiration.
Expiration while on EPAP therapy ^[works as CPAP]:
- expiratory back pressure created by EPAP devices helps to expand the airway
## Inspire – Hypoglossal Nerve Stimulator
- Implantable pulse generator that stimulates the hypoglossal nerve at the submandibular region at the start of inspiration.
- This activates the genioglossus muscle resulting in tongue protrusion and airway opening.
- The patient turns the device on/off, pauses therapy and adjust stimulation voltage using an external remote.
- Currently used mainly in adult OSA patients with a BMI <35kg/m2, AHI 15 -65/hr who are intolerant of CPAP and without complete concentric collapse of the velopharynx on drug-induced sleep endoscopy.
Describe the necessary criteria in follow-up
- CHECK COMPLIANCE - a big problem
- CHECK FOR SIDE-EFFECTS - can impact compliance
- CHECK FOR IMPROVEMENT IN SYMPTOMS - note: snoring vs. sleepy
- FOLLOW-UP SLEEP STUDY especially if surgery was involved
- CHRONIC DISEASE = LONG TERM CARE
