L20 - Sleep Apnea Flashcards
What are the 2 types of sleep apnea?
Obstructive - can’t breathe - respiratory efforts but no breathing
Central - won’t breathe - no respiratory effects - not trying.
what is sleep apnea?
Condition characterised by absent or greatly reduced breathing during sleep.
O2 FALLS CO2 RISES
Apnea definition?
termination of airflow for >10 secs
Hypopnea definition?
a >50% reduction in airflow for >10sec associated with either an arousal from sleep or a >3% fall in arterial oxygen saturation.
What is classified as norma, mild, moderate and severe apnea/hypopnea index?
normal - less than 5 events per hr
mild 5-15 events/hr
moderate 15-30 events/hr
severe - 30 + events/hr
What causes Central Sleep Apnea?
- Breathing stops bc patient does not make any breathing efforts during sleep
can happen due to
- CONGESTIVE HEART FAILURE - damaged heart delays feedback of blood O2/CO2 levels to the brain
- CONGENITAL CENTRAL HYPOVENTILATION - genetic condition of abnormal RTN function such that patients do not respond to CO2 (RTN = main part of brain that responds to co2)
- OPIOIDS - reduce the responsiveness to low o2 and high co2 (RTN and peripheral chemoreceptors) and inhibits the pre-boeztinger neurons (pacemaker breathing cells).
these people are OK when awake, bc there are other stimulants keeping them breathing - but they rely on CO2 sensing when sleeping
What are the consequences of central sleep apnea?
Congestive heart failure - sleepiness, disturbed sleep by 3-5 second microarousals.
Congenital central hypoventilation Syndrome - death or serious brain damage
Opioids - death by accidental overdose
Describe obstructive sleep apnea
A prevalent disorder of repetitive upper airway collapse during sleep.
Breathing efforts continue during sleep.
What is sleep like for obstructive sleep apnea patient?
- decreased REM. doesn’t increase over the night
- no SWS - they don’t sleep long enough to reach SWS. keep waking up.
- many arousals.
What causes obstructive sleep apnea?
- small upper airways!
- increased fat, obesity is a risk factor.
- They can usually breathe when awake, as the high genioglossus (GG, Tongue) and keeps it open, but muscles relax in sleep causing it to relax.
- losing weight can prevent 15 events pr hr
What is neuromusclar compensation?
This refers to the high genioglossus holding the upper airway open in obstructive sleep apnea open
study has found that even in sleep, these patients have more muscle activity than controls, but it is not enough to keep airway from collapsing
What has using a single EMG recording shown us about apnea?
- records electrical potential of single motor units.
- found that there are seperate inputs. one stop’s firing completely in sleep, and follows the same pattern of breathing, in wake.
therefore
SLEEP influences BREATHING which influences MUSCLE ACTIVITY/ACTION POTENTIALS.
Describe the cycle of obstructive sleep apnea pathophysiology.
Dilator muscle activity falls –> obstruction –> low levels of O2/high CO2 –> arousal –> airway opens –> hyperventilation –> falls back asleep –> RESTART CYCLE
What are the consequences of OSA?
- repetitive arousal during sleep - fragmented sleep
- low oxygen levels
- behavioural and neurocog
- –> excessive daytime sleepiness in severe OSA
- –> mood and behavioural - 40% have depression - irrable, impatient and moody - anxiety and PTSD also more common
- –> imapired attention/vigilance
- –> impaired memory and learning, possibly due to reduced hippocampal volume (due to low o2 )
- cardio vasc and metabolic
what did the APPLES study find?
Apnea Positive Pressure Long-term Efficacy Study
found that after 6 months of treatment using CPAP, 4 hours a night - there were no improvements in exec func, attention, psychomotor performance, learning and memory.
only improved EDS
are the changes due to apnea permanent?
