Disorders of Ventilation

Question 1

How common is Primary alveolar hypoventilation (Odine’s Curse)?

Describe the pathology.

When during the day is it worse?

What is the etiology? 2

Answer 1

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

Question 2

Patient profile of Primary alveolar hypoventilation (Odine’s Curse):

1. weight?
2. gender?
3. age?
4. Present with what symptoms?3
5. What will we see on physical exam? 4

Answer 2

1. Usually non-obese
2. Males in their 3rd of 4th decade
3. Present with
   - lethargy,
   - headache and
   - somnolence
4. Physical exam
5. No dyspnea
6. Cyanosis
7. Evidence of Pulm HTN

Question 3

What labs should we get for hypoventilation? 4
Imagaing? 3
Tests? 3

Answer 3

Labs:

1. chem,
2. TSH,
3. CBC,
4. ABG

Imaging:

1. CXR (rule out lung disease)
2. Brain imaging CT/MRI (rule out stroke, tumor)
3. Echo (right heart changes from chronic hypoxemia)

Tests:

1. PFTs
2. Can include negative inspiratory pressure to rule out neuromuscular disease
3. Muscle stimulation tests/nerve conduction velocity to rule out neuromuscular disease

Question 4

1. What disease process results secondary to hypoxemia?

2. GIve an example of a disease where this would occur?

Answer 4

1. pulmonary hypertension
   (shunts blood to an area where it can pick oxygen up)
2. Sleep apnea pts for example

Question 5

Treatment of primary alveolar hypoventilation

4

Answer 5

1. Supplemental oxygen
2. Positive pressure ventilation
3. Respiratory stimulants
   - -Medroxyprogesterone
   - -Acetazolamide
   - -Theophylline
4. Diaphragm pacing with phrenic nerve stimulation

Question 6

What is Pickwickian Syndrome?

Answer 6

Blunted ventilatory drive and increased mechanical load imposed upon the chest by obesity

Question 7

In Pickwickian Syndrome, why would the pt voluntarily hyperventilate?

What is the pt also likely to have?

Answer 7

Voluntary hyperventilation returns the Pco2 and Po2 toward normal values

Most likely also have obstructive sleep apnea

Question 8

Treatment for Pickwickian Syndrome?

4

Answer 8

1. Weight loss
2. NPPV (noninvasive positive pressure ventilation) is helpful (Bipap (those who cant support their tidal volume, CPAP)
3. Tracheostomy
4. Respiratory stimulants (not the primary treatment)
   - -Theophylline
   - -Acetazolmide

Question 9

Describe the process of hyperventilation?

Causes?
10

Answer 9

Increase in alveolar ventilation that leads to decreased CO2

1. Brainstem injury
2. Pregnancy
3. Hypoxemia
4. Lung diseases (that cause hypoxia)
5. Sepsis
6. Liver failure
7. Fever
8. Pain
9. Anxiety
10. Hyperthyroidism

Question 10

Signs and Symtpoms of Acute hyperventilation?

8

Answer 10

1. Rapid respiratory rate
2. Paresthesias
3. Carpopedal spasm
4. Tetany
5. Anxiety
6. Arrhythmias
7. Cerebral vasoconstriction and cerebral ischemia
8. Seizures

Question 11

Treatment of hyperventilation?

3

Answer 11

Treat underlying cause

1. Pursed lip breathing (have them do this to slow it down) or
2. Rebreathing expired gas from a paper bag
3. Anxiolytic drugs (antiaxiety)

Question 12

Describe the symptoms of chronic hyperventilation?

5

Answer 12

Nonspecific symptoms that can be reproduced by voluntary hyperventilation

1. Fatigue
2. Dyspnea
3. Anxiety
4. Palpitations
5. Dizziness

Question 13

What is OSA caused by?

What happens becuase of this?3

Answer 13

recurrent collapse of the pharyngeal airway during sleep

1. Cessation of airflow
2. Disturbances in gas exchange
3. Poor sleep quality (reduced REM sleep)

Question 14

Sleep apnea risk factors

12

Answer 14

1. Obesity
2. Advancing age
3. Smoking
4. Craniofacial or upper airway soft tissue abnormalities
5. Nasal congestion
6. Pregnancy
7. End stage renal disease
8. CHF
9. Chronic lung disease
10. Family history
11. Menopause
12. Hypothyroidism

Question 15

Patient factors associated with a high likelihood of sleep apnea
3

Answer 15

1. Neck circumference:
2. Narrowing of the lateral airway walls,
3. Enlarged (ie, “kissing”) tonsils (3+ to 4+)

Question 16

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?

Answer 16

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

Question 17

Signs and symptoms that are suspicious for sleep apnea

16

Answer 17

1. HTN
   (esp. difficult to control)
2. Excessive daytime somnolence
3. Morning sluggishness
4. AM headaches
5. Daytime fatigue
6. Cognitive impairment
7. Impotence
8. Obesity
9. Loud snoring
10. Witnessed apneas
11. Nocturnal restlessness
12. Personality changes
13. Poor judgement
14. Depression
15. Memory impairment
16. Falling asleep while driving or in the waiting room

Question 18

Complications that arise from sleep apnea?

5

Answer 18

1. Motor vehicle crashes (2-3 times more common)
2. High users of medical resources
3. Cardiovascular disease
4. Increased risk of perioperative complications
5. 2-3 X increased risk of all cause mortality (untreated severe sleep apnea)

Question 19

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

Answer 19

1. HTN,
2. Pulmonary HTN,
3. CAD,
4. arrhythmias,
5. CHF,
6. CVA
7. Insulin resistance,
8. DM,
9. metabolic syndrome,

Question 20

OSAHS leads to what three things that cause metabolic syndrome? 3

What two other things contribute to metabolic syndrome? 2

Answer 20

1. Hypertension
2. Insulin Resistance
3. Proimflammatory/Oxidative stress

Obesity
Hyperlipidemia

Question 21

Questions to ask to screen for sleep apnea?

7

Answer 21

1. Are you tired during the day?
2. Have you ever fallen asleep while driving?
3. Do you fall asleep reading, watching TV or watching a movie?
4. Do you ever fall asleep at work?
5. If you are sitting quietly at home are you likely to fall asleep if you are not actively engaged in something?
6. Do you snore?
7. 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?

Question 22

How would we diagnose sleep apnea? (rule out other diseases)

4

Answer 22

1. Lab tests TSH, RBC (polysithemia)
2. Polysomnography (in-lab)
3. Home testing may be available for screening purposes
4. Home overnight oximetry testing has a high negative predictive value for sleep apnea when normal

Question 23

Define the following:

Apnea
Hypopnea
Apnea-hypopea index (AHI)
Respiratory disturbance index (RDI)

Answer 23

1. Apnea
   Breath cessation for at least 10 seconds with decrease in O2 saturation
2. Hypopnea
   Decreased airflow with a drop in O2 saturation of at least 4%
3. Apnea-hypopnea index (AHI)
   The number of combined events per hour
4. Respiratory disturbance index (RDI)
   The number of apneas, hypopneas and respiratory effort related arousals per hour of sleep

Question 24

What does a Polysomnography (Sleep study) record?

7

Answer 24

1. EEG (electroencephalography)
2. Electro-oculography
3. EMG (electromyography)
4. EKG
5. Pulse oximetry
6. Respiratory effort
7. Airflow

Question 25

For the Respiratory Disturbance Index, what values constitute: Mild sleep apnea? Moderate? Severe? Need to know Explain what the number means

Answer 25

``` 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

Question 26

Treatment for sleep apnea? 7 | whats the main treatment?

Answer 26

1. Weight loss 2. Sleep positioning 3. Avoidance of respiratory suppressants like ETOH, narcotics 4. CPAP (main treatment) 5. BiPaP 6. Oral (dental) appliances 7. Surgery - --Uvulopalatophyaryngoplasty (UPPP)

Question 27

Why are you at such a high risk for cardiac problems with sleep apnea?

Answer 27

promotes arterial thrombosis

Question 28

What is the difference between a CPAP (2) and BiPAP (5)?

Answer 28

CPAP 1. Continuous positive airway pressure 2. Standard treatment for OSA BiPAP (Bilevel positive airway pressure) 1. Non-invasive positive pressure ventilation 2. For use when taking a deep breath is difficult 3. Lower pressure for exhalation and higher pressure for inhalation 4. Can have a “back up rate” to augment respiratory rate 5. Used for mixed (obstructive and central) sleep apnea and also for impending respiratory failure

Question 29

What is central sleep apnea? What is it often mixed with? What pts can this be seen in? 4

Answer 29

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 ```

Question 30

Conditions that may be associated with central sleep apnea: | 8

Answer 30

1. Congestive heart failure 2. Hypothyroid Disease 3. Kidney failure 4. Neurological diseases, such as 5. Parkinson’s disease, 6. Alzheimer’s disease, and 7. amyotrophic lateral sclerosis (ALS or Lou Gehrig's disease) 8. Damage to the brainstem caused by encephalitis, stroke, injury, or other factors