Disorders of Ventilation Flashcards
How common is Primary alveolar hypoventilation (Odine’s Curse)?
Describe the pathology.
When during the day is it worse?
What is the etiology? 2
Rare
Inadequate alveolar ventilation
–normal neurologic function, airways, lungs, chest wall and ventilatory muscles.
Hypoventilation is worse during sleep
Etiology is congenital or severe trauma/insult to the brainstem
Patient profile of Primary alveolar hypoventilation (Odine’s Curse):
- weight?
- gender?
- age?
- Present with what symptoms?3
- What will we see on physical exam? 4
- Usually non-obese
- Males in their 3rd of 4th decade
- Present with
- lethargy,
- headache and
- somnolence - Physical exam
- No dyspnea
- Cyanosis
- Evidence of Pulm HTN
What labs should we get for hypoventilation? 4
Imagaing? 3
Tests? 3
Labs:
- chem,
- TSH,
- CBC,
- ABG
Imaging:
- CXR (rule out lung disease)
- Brain imaging CT/MRI (rule out stroke, tumor)
- Echo (right heart changes from chronic hypoxemia)
Tests:
- PFTs
- Can include negative inspiratory pressure to rule out neuromuscular disease
- Muscle stimulation tests/nerve conduction velocity to rule out neuromuscular disease
- What disease process results secondary to hypoxemia?
2. GIve an example of a disease where this would occur?
- pulmonary hypertension
(shunts blood to an area where it can pick oxygen up) - Sleep apnea pts for example
Treatment of primary alveolar hypoventilation
4
- Supplemental oxygen
- Positive pressure ventilation
- Respiratory stimulants
- -Medroxyprogesterone
- -Acetazolamide
- -Theophylline - Diaphragm pacing with phrenic nerve stimulation
What is Pickwickian Syndrome?
Blunted ventilatory drive and increased mechanical load imposed upon the chest by obesity
In Pickwickian Syndrome, why would the pt voluntarily hyperventilate?
What is the pt also likely to have?
Voluntary hyperventilation returns the Pco2 and Po2 toward normal values
Most likely also have obstructive sleep apnea
Treatment for Pickwickian Syndrome?
4
- Weight loss
- NPPV (noninvasive positive pressure ventilation) is helpful (Bipap (those who cant support their tidal volume, CPAP)
- Tracheostomy
- Respiratory stimulants (not the primary treatment)
- -Theophylline
- -Acetazolmide
Describe the process of hyperventilation?
Causes?
10
Increase in alveolar ventilation that leads to decreased CO2
- Brainstem injury
- Pregnancy
- Hypoxemia
- Lung diseases (that cause hypoxia)
- Sepsis
- Liver failure
- Fever
- Pain
- Anxiety
- Hyperthyroidism
Signs and Symtpoms of Acute hyperventilation?
8
- Rapid respiratory rate
- Paresthesias
- Carpopedal spasm
- Tetany
- Anxiety
- Arrhythmias
- Cerebral vasoconstriction and cerebral ischemia
- Seizures
Treatment of hyperventilation?
3
Treat underlying cause
- Pursed lip breathing (have them do this to slow it down) or
- Rebreathing expired gas from a paper bag
- Anxiolytic drugs (antiaxiety)
Describe the symptoms of chronic hyperventilation?
5
Nonspecific symptoms that can be reproduced by voluntary hyperventilation
- Fatigue
- Dyspnea
- Anxiety
- Palpitations
- Dizziness
What is OSA caused by?
What happens becuase of this?3
recurrent collapse of the pharyngeal airway during sleep
- Cessation of airflow
- Disturbances in gas exchange
- Poor sleep quality (reduced REM sleep)
Sleep apnea risk factors
12
- Obesity
- Advancing age
- Smoking
- Craniofacial or upper airway soft tissue abnormalities
- Nasal congestion
- Pregnancy
- End stage renal disease
- CHF
- Chronic lung disease
- Family history
- Menopause
- Hypothyroidism
Patient factors associated with a high likelihood of sleep apnea
3
- Neck circumference:
- Narrowing of the lateral airway walls,
- Enlarged (ie, “kissing”) tonsils (3+ to 4+)
How big does neck circumference have to be to beome a risk factor for sleep apnea? (men and woman)
What is a predictor in men but not women?
greater than 43 cm (17 in) in men and 37 cm (15 in) in women.
Narrowing of the lateral airway walls, which is an independent predictor of the presence of OSAHS in men but not women
Signs and symptoms that are suspicious for sleep apnea
16
- HTN
(esp. difficult to control) - Excessive daytime somnolence
- Morning sluggishness
- AM headaches
- Daytime fatigue
- Cognitive impairment
- Impotence
- Obesity
- Loud snoring
- Witnessed apneas
- Nocturnal restlessness
- Personality changes
- Poor judgement
- Depression
- Memory impairment
- Falling asleep while driving or in the waiting room
Complications that arise from sleep apnea?
5
- Motor vehicle crashes (2-3 times more common)
- High users of medical resources
- Cardiovascular disease
- Increased risk of perioperative complications
- 2-3 X increased risk of all cause mortality (untreated severe sleep apnea)
What kind of cardiovascular disease are sleep apnea pts at a high risk for? 6
What kind of endocrine probelms are sleep apnea pts at risk for? 3
- HTN,
- Pulmonary HTN,
- CAD,
- arrhythmias,
- CHF,
- CVA
- Insulin resistance,
- DM,
- metabolic syndrome,
OSAHS leads to what three things that cause metabolic syndrome? 3
What two other things contribute to metabolic syndrome? 2
- Hypertension
- Insulin Resistance
- Proimflammatory/Oxidative stress
Obesity
Hyperlipidemia
Questions to ask to screen for sleep apnea?
7
- Are you tired during the day?
- Have you ever fallen asleep while driving?
- Do you fall asleep reading, watching TV or watching a movie?
- Do you ever fall asleep at work?
- If you are sitting quietly at home are you likely to fall asleep if you are not actively engaged in something?
- Do you snore?
- If yes to snoring…Do you snore so loud that you aren’t invited to the yearly hunting camp anymore or do they make you get your own trailer/tent?
How would we diagnose sleep apnea? (rule out other diseases)
4
- Lab tests TSH, RBC (polysithemia)
- Polysomnography (in-lab)
- Home testing may be available for screening purposes
- Home overnight oximetry testing has a high negative predictive value for sleep apnea when normal
Define the following:
Apnea
Hypopnea
Apnea-hypopea index (AHI)
Respiratory disturbance index (RDI)
- Apnea
Breath cessation for at least 10 seconds with decrease in O2 saturation - Hypopnea
Decreased airflow with a drop in O2 saturation of at least 4% - Apnea-hypopnea index (AHI)
The number of combined events per hour - Respiratory disturbance index (RDI)
The number of apneas, hypopneas and respiratory effort related arousals per hour of sleep
What does a Polysomnography (Sleep study) record?
7
- EEG (electroencephalography)
- Electro-oculography
- EMG (electromyography)
- EKG
- Pulse oximetry
- Respiratory effort
- Airflow
For the Respiratory Disturbance Index, what values constitute:
Mild sleep apnea?
Moderate?
Severe?
Need to know
Explain what the number means
Mild sleep apnea -5-14/hr Moderate sleep apnea -15-29/hr Severe sleep apnea -≥ 30/hr
you stopped breathing 30 times an hour and woke up to a lighter level of sleep
Treatment for sleep apnea? 7
whats the main treatment?
- Weight loss
- Sleep positioning
- Avoidance of respiratory suppressants like ETOH, narcotics
- CPAP (main treatment)
- BiPaP
- Oral (dental) appliances
- Surgery
- –Uvulopalatophyaryngoplasty (UPPP)
Why are you at such a high risk for cardiac problems with sleep apnea?
promotes arterial thrombosis
What is the difference between a CPAP (2) and BiPAP (5)?
CPAP
- Continuous positive airway pressure
- Standard treatment for OSA
BiPAP (Bilevel positive airway pressure)
- Non-invasive positive pressure ventilation
- For use when taking a deep breath is difficult
- Lower pressure for exhalation and higher pressure for inhalation
- Can have a “back up rate” to augment respiratory rate
- Used for mixed (obstructive and central) sleep apnea and also for impending respiratory failure
What is central sleep apnea?
What is it often mixed with?
What pts can this be seen in?
4
No ventilatory effort seen during episodes of apnea as determined during the polysomnogram
Brain forgets to tell the body to breathe
Most often seen mixed with obstructive sleep apnea
Can be seen in 1. premature infants Clinically common in 2. post stroke, 3. traumatic brain injury and 4. CHF
Conditions that may be associated with central sleep apnea:
8
- Congestive heart failure
- Hypothyroid Disease
- Kidney failure
- Neurological diseases, such as 5. Parkinson’s disease,
- Alzheimer’s disease, and
- amyotrophic lateral sclerosis (ALS or Lou Gehrig’s disease)
- Damage to the brainstem caused by encephalitis, stroke, injury, or other factors
