6. Respiratory physiology during normal sleep
⢠Regulated by:
⢠1. Chemical factors: O2, CO2, acidosis
⢠2. Mechanical signals from lung, airway, and chest
receptors
7. ⢠REM sleep: decreased sensory and motor function
->impairment of ventilatory responses->
hypoventilation
Respiratory physiology cont...
8. Hypoxic and hypercapnic ventilatory response during
sleep
⢠During sleep voluntary control of respiration
is lost
⢠Ventilatory responses to both low O2 and high Co2
levels blunted -> marked hypoxemia seen during
REM sleep
Respiratory physiology cont...
12. ⢠Snoring:
⢠sound generated by the vibration of the pharyngeal
soft tissues.
⢠40% of men and 20% of women
Classification cont...
13. Upper Airway Resistance Syndrome
⢠UARS is characterized by respiratory effortârelated
arousals (RERAs).
⢠A RERA is defined as a sequence of breaths over at
least 10 seconds with increasing respiratory effort
that terminates with an arousal.
Classification cont...
14. ⢠Obstructive Sleep Apnea Syndrome
⢠Five or more respiratory events (apneas,
hypopneas,or RERAs) in association with excessive
daytime somnolence, waking with gasping, choking,
or breath-holding, or witnessed reports of apneas,
loud snoring, or both.
Classification cont...
15. ⢠EPIDEMIOLOGY and RISK FACTORS
⢠Obesity and Metabolic syndrome
⢠Neck size
⢠Adults and children with Down Syndrome
⢠Children with large tonsils and adenoids
17. Aetiopathogenesis
⢠Nose
⢠Nasal blockage might:
⢠Reduce nasal afferent reflexes that help to maintain
muscular tone of the upper airway
⢠Augment the tendency for mouth opening
21. ⢠Pharyngeal soft tissues:
⢠Supine position
⢠MRI volumetric studies->tongue
size as a major predictor
⢠Sagittally oriented airways that were speculated to
result in unfavorable muscular mechanics for
reopening the airway
Aetiopathogenesis contd...
22. ⢠Oral to palatal airspace is smaller, and the posterior
airspace behind both the tongue and palate is
narrower.
⢠Cross-sectional shape of the airway- elliptical
⢠Biomechanically weaker structure that is more easily
collapsed at less negative pressures.
Aetiopathogenesis contd...
25. ⢠Fujita classified ( Anatomical basis)
⢠Type I- collapse in the retropalatal region
⢠Type II- collapse in both retropalatal and retrolingual
regions
⢠Type III- collapse in the retrolingual region only
29. ⢠BMI
⢠Neck circumference
⢠Complete head and neck examination
⢠Mullerâs manoeuvre
Clinical Presentation contd...
30. Diagnosis
⢠Detailed history:
⢠Obtained in three settings
⢠First- routine health maintenance evaluation
⢠Second- evaluation of symptoms of OSA
⢠Third- comprehensive evaluation of patients of high
risk for OSA
31. ⢠Overnight oximetry:
⢠Oxygen desaturation index
subject with ODI of 55, 4 percent oxygen dips per hour. This trace shows the whole night's
data. Minimum oxygen saturation is approximately 45 percent
34. ⢠Four types of sleep studies
⢠Level I:
⢠Standard PSG with a minimum of seven parameters
measured, including EEG, EOG, EMG, and EKG, as
well as monitors for airflow, respiratory effort, and
oxygen saturation.
35. ⢠Level II:
⢠Comprehensive portable PSG studies are essentially
the same, except that a heart rate monitor can
replace the ECG
36. ⢠Level III
⢠Modified portable sleep apnea testing is a
cardiorespiratory study in which a minimum of 4
parameters must be measured, including
ventilation , heart rate or EKG, and oxygen saturation
37. ⢠Level IV:
⢠Continuous (single or dual) bioparameter recordings
where devices that measure a minimum of one
parameter, usually oxygen saturation are utilized
41. ⢠Polysomnography can also diagnose other sleep
disorders:
⢠Narcolepsy
⢠Periodic limb movements disorder (moving your legs
often during sleep)
⢠REM behavior disorder
42. Indices of Sleep-Disordered Breathing
⢠Apnea index- Number of apneas per hour of
total sleep time
⢠Hypopnea index- Number of hypopneas per hour of
total sleep time
⢠Apnea-hypopnea index Number of apneas and
hypopneas per hour of total sleep time
43. ⢠Respiratory effortârelated arousals (RERAs) index-
Number of RERAs per hour of total sleep time
⢠Respiratory disturbance index (RDI)-Number of
apneas, hypopneas, and RERAs per hour of total
sleep time
Indices of Sleep cont....
44. ⢠Central apnea index- Number of central apneas per
hour of total sleep time
Indices of Sleep cont....
45. ⢠Types
⢠Mild OSA: AHI of 5-15
⢠Involuntary sleepiness during activities that require little
attention, such as watching TV or reading
⢠Moderate OSA: AHI of 15-30
⢠Involuntary sleepiness during activities that require some
attention, such as meetings or presentations
Classification cont...
46. ⢠Severe OSA: AHI of more than 30
⢠Involuntary sleepiness during activities that require
more active attention, such as talking or driving
Classification cont...
47. ⢠Pulse transit time: interval between the R wave on an
electrocardiogram (ECG) and the arrival of the pulse
at the finger.
⢠Increased in increased respiratory effort and
decreased in the presence of tachycardia associated
with arousal.
50. Consequences of Untreated Obstructive
Sleep Apnea
⢠He and colleagues- apnea index >20ď increased
mortality
⢠Motor vehicle accidents by 2.5-fold
⢠Threefold increase in fatal and nonfatal
cardiovascular events
OSA: regarded as a condition characterized by repetitive upper airway obstruction leading to sleep fragmentation, cardiovascular stimulation and oxygen desaturation during sleep. Together, these lead to symptoms such as snoring, unrefreshing sleep, excessive daytime sleepiness (EDS), and the increased risk of cardiovascular disease, hypertension, insulin resistance, cerebrovascular disease and road traffic accidents.
Complet cessation at ant nares for 10 sec whether asso O2 desat or arousal, Hypoap: reduc of airflo of betw 50 to 90%(with or without 3% or more O2 desat and/or arousal
Sleep: 7-8hr, Stage I- alpha and theta,easily aroused stage II- sleep spindles or K complexes, Stage III &IV- delta, deep sleep
Muscles tone reduced, EEG: mixed frequency with low voltage, saw tooth waves
Inhibition of both presynaptic and postsynaptic afferent neurons results in an increase in sensory arousal thresholds to external stimuli
Hypoxia: many subjects remain asleep with oxygen saturation as low as 70% ,Patients with sleep apnea reduced arousal sensitivity to hypoxia during periods of asphyxia
Hypercapnia: most subjects are awake before the end-tidal Co2 rises by 15 mm Hg above the level in wakefulness
1. exacerbated by ingestion of alcohol, sedative use, and weight gain. 2. accidents and increased cardiovascular morbidity and mortality
Smoking; through oxidative stress, endothelial dysfunction and abnormal inflammatory response
which destabilizes the lower pharyngeal airway (by posterior rotation, vertical opening, and inferior displacement of the hyoid)
hyoid muscles-hyoid posi-> geniohyoid), tongue position (e.g. genioglossus) and palate position (e.g. tensor palatini), stiffen the upper airway and oppose the negative airway pressure generated by contraction of the diaphragm, delay between the upper airway muscle activity and diaphragmatic activity during inspiration->neg intraluminal pressure when upper airway muscl inactive
Supin-tongue projects posteriorly
Changes in tissue mass, lung volume, tracheal tug, and vascular volume from nonsupine to supine, as mass increases, gravity effects will increase.
Balance of Forc: Dilating forces include upper airway muscle tone, mechanical force of the airway wall structure, and positive intraluminal airway pressure. Collapsing forces include tissue mass,surface adhesive forces, and negative intraluminal pressures.
ideal Starling resistor is depicted for differing conditions of upstream pressure (Pus) in BâD. The pressure difference (ie, transmural pressure Pin -Pout =Ptm) across the airway determines airway size. In (B), fluid fills the basin and the pressure outside the tube (Pout) is greater than pressure inside (Pout >Pin), the tube collapses and no flow occurs. In (C), upstream pressure is increased. When dilating pressures are greater than collapsing pressures (Pin > Pout), the tube is patent and flow occurs. In (D) flow increases with increased positive upstream pressures and unchanged downstream pressures.
Flow is determined by upstream pressure.
overnight oximetry may miss subjects with OSA who do not desaturate, young, less obese subjects may not have oxygen desaturations in the presence of apnoeas and hypopnoeas and therefore will not be identified by oximetry. ODI: number of times the oxygen saturation falls by 4 percent averaged out per hour) of over 15 per hour may be suggestive of OSA. ODI > 15 per hour can only be used if the resting saturation of oxygen is above 90 percent
Adv: patient comfort, cost savings, prevention of hospital admission and speed of analysis data. Disadv: include sensor failure at home and loss of signal
(which may lead to repeat studies)r
refers to the recording of multiple sleep-related signals. allows qualitative and quantitative documentation of abnormalities of sleep and wakefulness, sleep-wake transition, and of physiological function of other organ systems that are influenced by sleep. Quistionnare, consent
depending upon the number of physiologica variables, Level I-technician is in constant attendance
Technician is not in constant attendance.
Ventilation: at least two channels of respiratory movement and airflow
Belt movement by piezoelectric sensors
(A) Displaying the trends in 10-second range increases the resolution of EEG waveforms. Alpha waves are clearly recognized in the EEG (C3, C4, O1, and O2) tracings. Frequency is determined by counting the ââpeaksââ in one-second interval. (B) Displaying the data in a compressed format (display range 480 seconds) accentuates the classical pattern of Cheyne-Stokes breathing.
Narcol: excessive daytime sleep & cataplexy. Periodic limb:  movement simulates triple flexion with leg flexion, ankle dorsiflexion, and great toe extension; it lasts approximately 2 seconds, REM Behavir dis: physically move limbs or even get up and engage in activities associated with waking. Some sleep talking, shouting, screaming, hittting or punching
Normal <5
Hypoxia-> sympa output->periphe vasocon-incre pulse and bpâ marker of subcort arousal , more sensitive measure of obstructive events than visible electroencephalogram (EEG) arousals found on full polysomnography
In children, sleep nasendoscopy can be performed with the child breathing spontaneously a mixture of halothane and oxygen. level 1- adenoid pad and velopharyngeal obstruction, level 2 tonsillar obstruction; level 3 tongue base obstruction; level 4 supraglottic obstruction.
subglottic stenosis, tracheomalacia, innominate artery compression, bronchomalacia or vascular rings
Children-Long-standing sleep apnoea can result in irreversible pulmonary hypertension, failure to thrive or a decrease in growth rate.
