Oxygenating with home BiPAP and CPAP machines

When using a ventilator, either for mechanical ventilation or noninvasive ventilation, a fixed FiO2 is set during ventilatory support. This is the best way of supplying supplemental oxygen to patients, especially because it may be adjusted to maintain a desired saturation.

However, when using a patient's home noninvasive ventilation equipment, either set up for BiPAP or CPAP, oxygen is typically placed directly into the circuit using a constant flow.  When this occurs, the amount of oxygen actually inhaled depends on a variety of factors:

• Oxygen flow
• Leakage
• Circuit
• Interface (face mask, nasal mask, etc.)
• Location of where oxygen is bleed into the system

Studies are still inconclusive as to where the best place to insert the oxygen into the system.  Some therapists place it near the machine, while others place it near the patient interface.  Ideally, the oxygen flow should be adjusted to maintain a desired Spo2.  This may be important for patients who are using their home units in the hospital setting.  

For patients who present in acute respiratory failure, when adequate oxygenation is not obtained with a patient's home unit, a ventilator (which may include a noninvasive ventilation device such as a Vision or V60) should be used in order to deliver a fixed FiO2 that can be easily adjusted to maintain an adequate SpO2.

References:

1. Storre, Jan H, Sophie E. Huttmann, Emelie Ekkernkamp, Stephan Wlterspacher, Claudia Schmoor, Michael Dreher, and Wolfram Windisch, "Oxygen Supplementation in Noninvnasive Home Mechanical Ventilation: The Crucial Roles of CO2 Exhalation Systems and Leakages," Respiratory Care, January, 2014, volume 59, number 1, pages 113-119

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Treatment for sleep apnea

So if you are diagnosed with sleep apnea, or are an RT or RN taking care of such a patient, you should be aware of the treatment for this condition.

1. Weight reduction: This often decreases the severity of the condition because it reduces fat tissue in the throat area.

2. Sleep posture: Sleep on sides instead of on back.

3. Quit smoking: Smoking is believed to increase inflammation in the lungs and also increase fluid retention in your throat and upper airway*

4. Avoid alcohol: Alcohol relaxes muscles of the throat and may interfere with breathing. This explains why people are more likely to snore after drinking*.

5. Avoid sleeping pills: These also relax throat muscles*.

6. Avoid sedatives: These too relax throat muscles*.

7. Avoid Caffeine: Within 2 hours of going to bed*.

8. Avoid Heavy Meals: Within 2 hours of going to bed*.

9. Maintain regular sleep hours: This will help you relax and sleep better. This keeps your circadian rhythm in sync.

10. Elevate head of bed 4-6 inches:

11. Keep nasal passages open: Use a dilator, airway sprays, decongestants, breathing strips. See a doctor if you have chronic nasal congestion.

12. Don't be stubborn: I find many sleep apnea patients don't get the treatment they need for no other reason that they are martyrs. Be willing to seek help, and be willing to accept help options when they are presented to you.

13. Supplemental oxygen: To help offset hypoxia that might occur and prevent hypoxia induced arrhythmias and pulmonary hypertension

14. Decreasing REM sleep: Decreasing REM may decrease apnea episodes. One medicine that does this is protriptylinee, which is a tricyclic antidepressant tht markedly reduces REM sleep.

15. Reduce daytime somnolence: Central nervous system stimulants such as methylphenidate may help in this area for obstructive or central sleep apnea.

16. Surgical interventions:

• Tracheostomy: Emergency management of severe onset
• Palatopharyngoplasty: Posterior section of palate and the uvula are resected (taken out), as well as tonsils and lateral posterior wall of the pharynx to remove soft tissue that might obstruct the airway.
• Mandibular advancement: If mandibular abnormalities are believed to be the cause, this can be corrected with surgery
• CPAP: Continuous Positive Airway Pressure helps keep the airways open from the tiniest alveoli to the soft upper airway tissue. It's effective only in obstructive sleep apnea. Other names for CPAP are EPAP (End Positive Airway Pressure) and PEEP (Positive End Expiratory Pressure).
• BiPAP: Bilevel Positive Airway Pressure. This is CPAP plus air that helps the patient take in a deep breath, more commonly referred to as pressure support (PS). The CPAP helps keep the airways open, and the PS helps the patient take in an effective breath. This is more commonly used when obstructive sleep apnea is more advanced, or when it is combined with COPD (particularly end stage COPD).
• Mechanical Ventilation: This is a short term solution for when the obstructive or central sleep apnea causes respiratory failure.
• Chest cuirass: May help a patient with central sleep apnea breathe.

References:

Egans Fundamentals of Respiratory Care (6th Edition, 1995)
*helpguide.org/life/sleepapnea

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Sleep Apnea

The Greek term "apnea" literally means "without breath." So when someone stops breathing, even for a short period of time while supposedly sleeping, this is what we refer to as sleep apnea. This "apnea" results in the patient not getting enough air to the lungs.

People with sleep apnea quit breathing repeatedly during the hours of sleep, often hundreds of times, according to the American Sleep Apnea Association. It's a disease that is more common than most people think, and many who have it are unaware they have it.

According to Egans Fundamentals of Respiratory Care, the scientific definition, and the one most medical professionals go by, is cessation of breathing for 10 seconds or longer. Likewise, it's diagnosed as 30 or more episodes of apnea in a six hour period

Symptoms of sleep apnea usually include:

• Excessive daytime sleepiness
• Fatigue
• Loud snoring
• Restless sleep
• Morning headaches
• Irritability
• Mood swings
• Depression
• Learnign difficulties
• Memory difficulties (Continued drops in oxygen cause loss of brain tissue)
• Sexual dysfunction

These symptoms are secondary to the patient constantly waking up during the night. Usually the patient doesn't even know he (or she) is waking up. And this results in "unexplainable" exhaution during the day.

A common sign of sleep apnea is snoring at night, periods were it looks like the person isn't breathing (apnea), and the feeling you need to smack the person in order to wake him up. This "poor quality" sleep results in tiredess during the daytime.

These patients have a hard time staying awake in school, at meetings, or while simply sitting around the house or office. In this way, it can effect your day to day living.

A greater concern is that it can effect your health in other ways too, such that when a person stops breathing, or takes inadequate breaths, oxygen levels (PO2) may drop to critical levels, and this places a strain on the heart.

As hypoxia occurs, the heart starts to beat faster in an effort to pick up more oxygen. The only time this wouldn't occur is if the heart is already weakened due to other conditions, or due to
In this sense, those with sleep apnea are at high risk for:

• Cardiovascular disease (due to constant drops in oxygen)
• Stroke
• High blood pressure (does not drop while sleeping)
• Arrhythmias
• Diabetes
• Sleep deprived driving accidents (due to lack of adequate sleep)

Likewise, if apnea periods are long enough, this can result in chronic hypoxia and chronic carbon dioxide retention (high CO2).

The diagnosis is usually made based on an evaluation and history of the patient and anyone who might be present with the patient while he is sleeping, such as a spouse. Diagnosis is generally made based on symptoms noted by the patient and family members.

Once it's believed the patient has sleep apnea, a sleep study is required to confirm the diagnosis, and to determine appropriate treatment. (see sleep study and treatment below).

There are three types of sleep apnea:

1. Obstructive (OSA): This is the most common. The soft tissue of the upper airway (throat) collapses and when the brain signals the body to take in a breath, it doesn't go in. Instead an effort is made, and perhaps a loud snore or gasp. This prevents oxygen from getting to the lungs, and results in hypoxemia (low oxygen to the blood) and hypoxia (low oxygen to the tissues).

This most commonly effects males ages 40-65, and may effect as much as 8% of the population, particularly obese males with large necks with little muscle tone. It's also more common in the elderly as opposed to young people.

Also of significance, about 20% of people diagnosed with OSA also have COPD. Hypoxia that occurs with COPD coupled with OSA may speed up the development of right heart failure.

Those at high risk for this include:

• Smokers
• Obese (the risk rises as weight rises)
• Age
• Diabetes (3 times the risk)
• Enlarged tonsils
• Enlarged adenoid
• Excessive pharyngeal tissue
• Goiter
• Large tongue
• Micrognathia
• Myotonic Dystrophy
• Shy-Drager Syndrome
• Hypothyroidism
• Accromegally
• Males (8 times the risk as females)

Usually these patients go to sleep lying on their backs and fall into a light sleep, and this is eventually followed by a deeper sleep.  In the deeper sleep the muscles and tissues of your body relax, and this is when the tissues in the throats of OSA patients collapse and thus block the airway.  The patient then reverts back into a light sleep and is easily awakened.

This can happen hundreds of times during the night.  When these patients wake in the morning they know they have been lying down for 8 hours, yet they don't remember waking up a bunch of times in the night.  The result is feeling tired all day.

2. Central: The airway is not blocked, but the does not send the usual signal to take in a breath. This is also called Cheyne-Stokes Respiration. Breathing has the following pattern: none... fastter... faster... faster... very fast... slower... slower... slower... slower... none...
Genrally, breathing cycles between periods of hyperpnea (rapid breathing), apnea and hypopnea (slow breathing). If the period of apnea (pause) is long enough, the patient's oxygen level can drop significantly.

3. Mixed: A combination of obstructive and central sleep apnea.  Symptoms of this disease have been recorded in the annuls of history for thousands of years.

There are two other types of sleep apnea that are often used:

4. Pickwickian Syndrome*: This is used to describe patients who are very obese and excess fat tissue on the chest wall and below the diaphragm prevents the lungs from becoming fully expanded. This results in shallow and ineffective breathing. This is often accompanied with obstructive sleep apnea. The term was coined in 1957 to describe the cardiorespiratory effects of ineffective breathing due to obesity.

It was about 1970 when it was determined by scientists that there was more to this condition than just obesity. They determined that these patients presented with daytime sleepiness, flaccid upper airway tissue, and respiratory abnormalities during sleep. It was from here that sleep apnea was defined as a diagnosis and divided into OSA and CSA.

Another reason Pickwickian Syndrome doesn't always apply to sleep apnea is because in some cases sleep apnea is present is patients who are not obese.

However, from time to time, you'll still see Pickwickian as a diagnosis. Yet, thechnically speaking, Pickwickian is not a form of sleep apnea, just a condition that usually presents with it.

5. Ondine's Syndrome**: According to German folklore, the nymph Ondine falls in love with a mortal who becomes unfaithful to her. When this happens, the king of the nymphs places a curse on the mortal. The curse is such that instead of breathing automatically without thinking about it, the mortal will have to think about it. If he doesn't make a conscious effort to breath -- as if he falls asleep -- he will stop breathing. If he forgets to breathe he will die.

This is the earliest description of Central Sleep Apnea and should not be used. Instead...

6. Congenital Central Hypoventilation Syndrom (CCHS)**: This is used to describe people (particularly newborns) who have periods of hypoventilation and hypoxemia without any cardiac or neuromuscular disease. They breathe normal while awake, and hypoventilate while sleeping. While hypoxemia and hypercapnia progress during hours of sleep, there is no natural inclination to wake up when CO2 gets high enough as in OSA.

However, CCHS is still often called Ondine's Curse, and still it's just another way of describing CSA.

Cardiac and pulmonary effects***:  While apnea is occuring the patient is not drawing in oxygen (O2) and not exhaling carbon dioxide (CO2), so oxygen in the blood drops (hypoxemia) and CO2 in the blood rises (hypercarbia).

Secondary to hypoxemia, the heart slows down (bradycardia).  This is the body's natural response to decrease the body's oxygen consumption when there is less oxygen available.  Once breathing resumes, the heart increases (tachycardia), and this is the body's natural tendency to find oxygen.

Systemic and pulmonary blood pressure rises during periods of apnea, probably due to hypoxemia.  This is where most cardiac dysrhymias occur, and it is also believed that it is probably a life threatening cardiac arrythmia caused by hypoxemia that causes OSA and CSA patients to die in their sleep.

Likewise, about 10% of sleep apnea patients have high blood pressure.

Conclusion:  Sleep apnea is a serious condition that may result in day time sleepiness that may effect the every day life of the patient, and may even result in premature death.  It may be up to family members and/ or the physician to recognize the symptoms, and knowing that obese men with thick necks are most at risk

More References:

*Guilleminault C, Eldridge FL, Simmon FB, et al: "Sleep apnea syndrome-Can it induce hemodynamic changes," West J. Med, 123: 7-16, July 1975

**http://emedicine.medscape.com/article/1002927-overview


***Wilkins, Robert L, Dexter, James R, "Respiratory Disease:  Principles of Patient Care," page 313, 1993

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