Sleep Studies

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Sleep disorders are a serious problem because sleep deprivation is tied to increased accidents. Some studies have compared sleep deprived persons with intoxication and found the resulting accident rates compatible. Fatigue is associated with 57% of truck driver accidents.

· Normal sleep averages 8 hours a day. Normal sleep is characterized by alterations between two types of sleep every 60 to 90 minutes

· Non-REM sleep: non-rapid eye movement sleep

o Has 4 stages:

§ First the patient goes into stage I in which he feels drowsy and his EEG 8-12 alpha waves

§ Within minutes he moves into stage 2 in which his EEG shows sleep spindles and K complexes [Theta waves]. This is a deeper level of sleep and this is the predominate stage of NREM sleep

§ Quickly goes into stages 3 and 4 characterized by slow-wave sleep [delta waves]. There are more delta waves in 4 than in 3. It is difficult to arouse someone who is at that level of sleep

§ After 60-90 minutes of non-REM sleep the patient moves into REM sleep

· Vital Signs during non-REM sleep: Respiratory rate slows and PaC02 rises 3-7 mmHg, Blood pressures drop about 5%-10% during the first 2 stages and then down 8%-14% during the last two stages. While respirations start out irregular in the first two stages, it becomes regular during deeper stages.

· REM sleep: rapid eye movement sleep

o Has slow low voltage random waves with saw tooth

o This is where we dream

o He rotates in and out of REM sleep about 5 times a night. Early in the evening REM sleep may only be 5 minutes long, but toward the morning, REM sleep can last as long as 30-60 minutes

o In adults and kids, REM sleep accounts for only 20%-25% of all sleep, in newborns this REM sleep lasts 55%-80% of the time.

· Vital signs during REM sleep: Because the patient is dreaming at this time, skeletal muscles are so relaxed that a partial state of paralysis results. Respiratory efforts are chaotic as responses to hypercapnia and to hypoxia are blunted. The patient is at most risk for upper airway obstruction and for hypoxemia during REM sleep. Heart rates are variable and the person is most at risk for cardiac arrhythmias at this point in sleep. Blood pressure tends to rise higher than during N-REM sleep

· Sleep apnea. Three types of Sleep apnea. Compare these types of sleep apnea.

o In adults, a cessation of air flow for 10 seconds or more is called apnea while a mere reduction of airflow by 50% is hypopnea.

o A normal adult male can have as much as 7 apneas/8hrs while women only have 2/8 hour. Needless to say they will be asymptomatic. A diagnosis of sleep apnea is the presence of 5 apnea/hour. This can be discovered with an over-night sleep study called a polysomnograph

o There are three types of sleep apnea

§ Obstructive sleep apnea in which the problem is upper airway occlusion during REM sleep. This is the most common sleep apnea with 2% of the adult population having OSA

· During the polysomnograph study the patient will be seen to have no gas flow but the chest continues to rise and fall.

· The majority of OSA happens during REM sleep

§ Central sleep apnea in which the patient suffers some CNS disturbance so that he fails to recognize or respond to hypercapnia or hypoxia. Only 10% of folks with sleep apnea have central sleep apnea

· During the polysomnograph study the patient will be seen to have no air flow because the chest failed to rise and fall

· The majority of central sleep apnea happens during transitions between awake to sleep during stage 1 of N-REM sleep

§ Mixed obstructive and central apnea. In most cases of mixed, the patient suffers Central sleep apnea followed by upper airway occlusion.

· During the polysomnograph study the patient will first be seen to have no air flow because the chest failed to rise and fall followed by chest wall movement without air flow

Signs and symptoms of obstructive sleep apnea. Identify high risk patients for this disorder.

S/S of OSA: On polysomnograph the patient will be seen to have a cessation of sleep that will last for 20-30 seconds accompanied by a desaturation of 5%. If the patient has a history of COPD, or cardiac problems, this desaturation could be as much as a 50% drop. He will have an increase in BP with a decrease in CO with both resolving as soon as breathing returns.

· There will be a history of cycles of apnea followed by arousal. Frequently the sleeping partner will notice the problem first

· With moderate to severe OSA, there will be a history of frequently falling asleep in the daytime when he relaxes such as in front of the TV.

· Memory loss, irritability, depression, poor sexual function

· Tends to happen in the supine position and in some will be corrected by positional changes: Positional Sleep Apnea

· 33% of OSA patients have an underlying HTN with spikes in the blood pressure in the AM.

· 36% will have a history of morning headaches from hypercapnia

· PVC and other cardiac arrhythmias—even short asystole is common

· Bedwetting [enuresis] is common

· Automatic behavior in which they act without knowing what they are doing

Who is at risk for OSA? Middle-aged to elderly males, who are obese, who have short necks with a history of snoring. History of alcohol use is significant. They frequently don’t know they have a problem

· On Physical Exam, you will find the uvula to be red & swollen from being scraped on the tongue all night when the airway collapses. This will increase his gag reflex. You may also see airway malformations, enlarged tonsils, or a deviated septum.

· Might have a large tongue or a small jaw

Signs and symptoms of central sleep apnea.

· Same basic symptoms of interrupted sleep

· tend to complain about insomnia more.

High risk patients for this disorder. Are older, snore only lightly, aren’t overweight. Frequently have some underlying medical problem that accounts for the apnea:

· History of damage to the medulla

· History of polio, Muscular Dystrophy or Myasthenia Gravis

· Cheyne-Stokes respirations associated with CHF are not considered a central sleep apnea because the patient’s CO is down which creates a lag in recognizing hypoxia. In Central sleep apnea the problem is neural, not circulation

Signs and symptoms of mixed sleep apnea.

· Same basic symptoms of interrupted sleep

High risk patients for this disorder

Link between COPD and sleep apnea.

· While there aren’t more COPD's with sleep apnea than not, it does complicate their case. Because they already have compromised ABG's the normal changes at night are more serious

· When they have desaturations, arrhythmias and hypoxic episodes, they are more serious

· They already suffer increased RAW so decreased RAW at night can get worse

The sleep study. What parameters are measured? A PSG study consists of multiple channel recorders attached to various wires to measure the following parameters:

· Upper chest muscle action: EOG

· Abdominal action: EOG

· EEG to determine sleep stages

· EKG to follow heart rates and rhythms

· Respiratory rates

· Airflow at the mouth and nose uses thermistor

· Sp02: ear pulse ox

· Eye movement: EOG

· Chin motion: EOG

· Leg movement: EOG

When is a polysomnograph indicated? According to the AARC guidelines

· A person with cor pulmonale whose daytime Pa02 is above 55 mmHg needs to be assessed at night.

· Anyone with s/s consistent with sleep deprivation, and sleep apnea need to be checked out.

· Anyone with nocturnal cardiac arrhythmias

What pre-test screening is required? because sleep needs vary so widely between one person and the next and because feelings of insomnia are subjective, a study of a persons’ daylight alertness, a multiple sleep latency test MSLT may be done to document that the loss of sleep is effecting the patient in a negative way. MSLT can also rule out narcolepsy.

· 12 lead EKG for underlying cardiac problems & to rule out cor pulmonale

· The patient’s drug or ethanol use needs to be established with interviews.

· Blood work such as thyroid levels need to be done to rule out hypothyroidism which will decrease entire metabolic rate.

What is an Apnea Index? Apnea/total hours of sleep. If the patient only suffers hypopnea then it is hypopnea/hours of sleep. An Apnea index of 5/hr is diagnostic of sleep apnea, an Apnea Index of more than 20 is associated with a high mortality

Findings associated with OSA on the sleep study graph

· On the PSG reading, the oral and nasal thermistors show zero flow rate while the chest wall and the abdomen show continued action. The Sp02 drops sharply after the flow stops

· This should happen during REM sleep

Findings associated with central sleep apnea on the sleep study graph.

· On PSG the chest and abdomen stop moving, then the air flow stops then the Sp02 drop a bit less.

· This should happen close to the transitional going in or out of stage 1 of N-REM sleep

Findings associated with mixed sleep apnea on the sleep study graph

· First you will have a central sleep apnea pattern, the airflow will stay down and the chest wall starts up again. The Sp02 drop will be moderate to severe

Treatments for OSA:

· Change ethanol or drug abuse

· Lose weight

· If positional sleep apnea, change to sleeping on the side

· Start CPAP while repeating PSG and alter settings until sleep apnea resolves

· Start BiPap & monitor with PSG

· Consider surgery on the upper airways. Only works in 20-50%

· Consider tracheostomy. Works for everyone, but has its drawbacks

Treatments for Central Sleep Apnea

· Diagnose and treat underlying cause if possible

· Position change oddly enough can help some with CSA

· Low flow 02