This document discusses obstructive sleep apnea (OSA) and obesity hypoventilation syndrome (OHS). It covers the definition, symptoms, risk factors, diagnosis through sleep studies, and treatment options including CPAP, weight loss interventions, and non-invasive ventilation. It notes that OSA is common in intensive care unit patients and discusses considerations for managing OSA and obesity in the ICU and perioperative settings.

2. Dr Rabinder Singh Randhawa
Consultant Chest Physician

3.  Sympathy for your local chest physician
 Understand OSA patients a little better
 Recognise OSA patients and dilemmas in their
journey
 Refer everyone for a sleep study and stay
awake……….
 Only 63 slides

4.  Patients with OSA have high incidence of co-
morbidities
 Obesity, diabetes, hypertension, ischaemic heart
disease,heart failure and cerebrovascular disease
 OSA is a common contributing cause of
hypercapnic respiratory failure

5.  Obesity related complications

6.  Raised intra-abdominal pressure- causing renal,
hepatic failure
 Raised intracranial pressures-as a result of raised
abdominal (and interpleural pressures)
 Raised central venous and pulmonary occlusion
pressures from above
 Moderate elevation of PAP from OSA/OHS

7.  Reduced lung capacity, vital capacity
 Decreased FRC, so desaturate faster and greater basal
atelactasis
 Decreased compliance
 Increased airway resistance and closure
 Poor ventilatory response to hypercapnic respiratory
failure

8.  OSA patients have a higher incidence of
admission to ICU
 Higher morbidity and mortality?

9.  Treated OSA is common in patients admitted to ICU
(about 8% in one large single center1)
 Treated OSA patients younger and more likely male
 Apache III scores lower, less critically ill
 Shorter median length of stay
 Decreased mortality(12,13)

10.  BMI<18.5 associated with poorer outcome
 BMI >30 associated with better outcome at least
until BMI of 40(3,4)

11.  Obese patients have greater nutritional
reserve(controversial with some studies showing
benefit and others showing none15.16)
 OSA patients younger than other cohorts
 Physicians have a lower threshold for admission to
ICU in OSA patients
 Patients with OSA better integrated in to health
care system (worried obese?)

12.  OSA and obesity and airways
-predictor of difficult airway
-apnoea to desaturation time significantly lower
-gastro-oesophageal reflux more common in obese and
OSA
-airway anatomical consideration incl retrognathia and
malampati scores

13.  Poor neck extension
 Difficult tracheostomy

14.  Patients are more vulnerable
 Safety increased by identifying OSA pre-op
 Regional rather than general anaesthetic
 Awake extubation
 Use of lateral rather than supine posture

15.  OSA patients have narrower airways
 ET tubes decrease upper airway reflexes
 NIV/CPAP applied early post extubation allow
earlier extubation in these patients
 Reverse Trendelenburg maximizes lung volumes

16.  Marked PAP increase in response to hypoxia
 More common with OHS patients with
parenchymal lung abnormality
 Careful cardiac monitoring and haemodynamic
management

17.  Recently recognised
 Abdomen can behave like a closed space, fat
accumulation, capillary leak
 Compression leads to ischaemia of kidneys, liver
 Worsened by co-existing ascites
 High index of suspicion required to diagnose and
treat

18. Intermittent narrowing or obstruction in the upper
airway during sleep
A spectrum- from ‘trivial’ snoring to repetitive
complete obstruction of the airway, leading to
desaturation and arousal from sleep
Leading eventually to sleep fragmentation and
excessive daytime sleepiness

19.  Apnoea-Defined arbitrarily as stopping breathing
for 10 seconds

20.  Hypopnoea-Reduction in nasal airflow by 50%
from baseline or a desaturation of 4%(3%) on
oximetry

21.  Obstructive- Associated with respiratory effort
 Central- No effort or flow
 Mixed- Can occur with any of the above

22.  Again, ‘normal’ s noted to have less than five per
hour in an average night
AHI/RDI
 5-15 Mild
 15-30 Moderate
 >30 Severe

23.  Can vary with age
 Not all patients are symptomatic
 Not a catch all definition (eg upper airway
resistance syndrome-normal AHI)

24.  ? Middle aged male disease
 2-3 times more in men than women
 No worldwide uniform criteria
 Approximately 4% of western population suffer
from clinically significant OSA
 If looking at men with a BMI of greater than 30, it
is greater than 20%
 Racial differences

25.  88 overnight oximetry studies ordered in 6 months
alone 2012 (?Low priority condition impact)
 78.5% male, Av BMI 36.6, collar size 18in
 41 positive studies (RDI>10) and 40 negative
studies
 31 patients referred for CPAP treatment in tertiary
centre

26.  More than 150 CPAP therapy machines issued
over 18 months (6 week adherence at 88%)
 More than 300 oximetries performed
 More than 120 partial polysomnographies
performed

27.  Upper airway –from nose and mouth to epiglottis
 Most narrowing occurs at pharynx
 Genioglossus activity decreased during sleep
 Used for breathing and swallowing
 Dilator muscles hold it open
 Floppy, collapsible for peristalsis

28.  During sleep, dilator muscle activity decreases
 Normal’ s can also show narrowing
 Therefore, narrowing can be functional or
anatomical at this site

29.  Neck adiposity- increased pressure on lumen
(neck circumference correlates better than any
other index of obesity with OSA)
 Craniofacial abnormalities- e.g retrognathia,
macroglossia, micrognathia
 Enlarged tonsils and adenoids (usually children)

30.  Nasal obstruction lowers the critical pressure at
which pharyngeal collapse occurs
 Pharyngeal muscle activity is increased during
wakefulness, with larger decrease during sleep in
OSA
 Pharyngeal pressure receptors can be damaged
by alcohol and smoking

31.  Drugs-opiates, benzodiazepines
 Neurodegenerative disorders-e.g MSA
 Myopathis- e.g Duchenne’s
 Hypothyroidism

32.  Tremendous negative pleural pressures required
to open airways cause arousal, sleep
fragmentation and excessive day time tiredness
 Long term sequelae of autonomic changes

33.  RTA’s-serious public health and safety issues
 Arterial hypertension
 Insulin resistance
 Arrythmias/Ischaemic heart disease
 Stroke

34.  Cor pulmonale
 Polycythaemia
 Neuropsychological impairment-Probably the
most overlooked by medics
 Poor anaesthetic outcome

35.  Occurs during sleep!
 Some important points during history:
Sleepiness
Unrefreshing sleep
Nocturnal choking
Nocturia
Witnessed apnoeas
 Bed partner’s account
 Epworth sleep score

36.  .
0 = Would never doze
1 = Slight chance of dozing
2 = Moderate chance of dozing
3 = High chance of dozing
Sitting and reading
Watching TV
Sitting inactive in a public place (for example a theatre or meeting)
As a passenger in a car for an hour without a break
Lying down to rest in the afternoon when circumstances permit
Sitting and talking to someone
 Sitting quietly after a lunch without alcohol
In a car, while stopped for a few minutes in traffic
A score of 10 or above can be indicative of EDT

37. • BMI
• Collar size
• Craniofacial examination
• Oral cavity
• Nasal patency
• Cardiovascular system/neurological system
• Respiratory
• Predisposing diseases-e.g
acromegaly/hypothyroidism

38.  Can be at home or in sleep centres
 Oximetry alone is useful as screening and will
identify majority
 Respiratory polygraphy- snoring,thoraco-
abdominal movements, nasal airflow, oximetry,
pulse, leg movements
 Full polysomnography-all of above plus EEG,
EOG and EMG

39.  Home polygraphy or oximetry in patients own
home preferred
 Reflect normal environment
 Cheaper, but some limitations of kit
 Can’t tell if patient truly slept, but patients usually
say so

43.  Oximetry - some false positive’s with Chayne –
Stokes breathing (eg CCF)
 False negatives with thin young patients who do
not desaturate

44.  Quality of life
 Occupation???
 Patient/partner motivation
 NICE-moderate to severe symptomatics
 Emerging data on patients with co-existing heart
failure, severe COPD

45.  CPAP is recommended as a treatment option for
adults with moderate or severe symptomatic OSA
 CPAP for mild OSA if
they have symptoms that affect their quality of life
and ability to go about their daily activities, and
lifestyle advice and any other relevant treatment
options have been unsuccessful or are considered
inappropriate

49.  Weight loss-???gastric banding
 Reduce night alcohol
 Sedative avoidance
 The ‘tennis ball’ position!
 Treat underlying medical problems
 Mandibular advancement for snorers and mild OSA

50.  CPAP- current gold standard
 Bariatric intervention
 Maxillary advancement in selected few
 Tracheostomy as last resort

53.  Class 1 licences- Stop on diagnosis but may
restart after successful treatment
 Class 2 licences- Generally loose license but may
appeal in individual cases with appropriate
evidence of compliance
 My practice-don’t drive whilst tired until diagnosis
reached

54.  Originally used to include OSA and COPD
 Now, also to describe obesity hypoventilation
 Alveolar hypoventilation leads to hypoxia and
hypercapnia
 Defined as the presence of day time
hypercapnia(>6kPa) and obesity

55.  Ventilation falls during REM sleep
 0.5 kPa rise in CO2 is normal
 In ‘normals’, there is no corresponding desaturation as
on flat part of oxyhaemoglobin curve
 In COPD/obesity hypoventilation, a small drop in
ventilation causes desaturation
 Extra resistive load of obstruction worsens hypoxia
and hypercapnia

56.  Correction of obstruction alone can sometimes
correct hypercapnia and hypoxia
 Most patients will require ventilation(NIV/Bilevel),
although some respond well to short term re-
setting and regain ventilatory drive

57.  Similar approach to OSA
 Day time hypercapnia and hypoxia should alert to
possibility
 Failure to respond to CPAP therapy alone

58.  Morbid obesity (BMI >40) unless co-existant
COPD
 Poor sleep quality
 Daytime sleepiness and drowsiness
 Features of polycythaemia and cor pulmonale

59.  Spirometry
 Clinical examination
 Day time arterial blood gasses
 Sleep study with or without transcutaneous CO2
measurement

60.  Most require NIV/BIPAP
 In some, NIV followed by CPAP is adequate