SLEEP STUDIES Written by: Melissa Dearing - LSC-Kingwood

Sleep Normally Pts with obstructive sleep apnea (OSA) Polysomnogram (PSG)

Key Terms apparent life-threatening events central apnea delta sleep hypopnea micrognathia multiple sleep latency test non–rapid eye movement sleep obstructive sleep apnea polysomnogram

Key Terms (con’t) rapid eye movement sleep respiratory disturbance index retrognathia sleep apnea sleep continuity theory sleep latency sudden infant death syndrome upper airway resistance syndrome

Facts about Sleep Disorders Sleep-related breathing disorders occur in about 5% of adult males, less in women. The incidence increases with age and may be as high as 37% in men over 60 years of age. Sleep disorders centers evaluate and diagnose sleep-related breathing problems. Respiratory therapists often are employed in the centers because of their expertise in monitoring breathing disorders.

Normal Sleep Stages Non-rapid eye movement (NREM) Rapid eye movement (REM)

REM Sleep Stages – Figure 18-1

NREM Sleep Non–Rapid Eye Movement Sleep (NREM) NREM is the first type of sleep entered by healthy sleepers. It has four different stages. The stages are recognized by electroencephalogram (EEG) changes during a sleep study. Stage 1 is the lightest stage of sleep. Sleepers in stage 1 are easily aroused. Stage 2 is the most common stage of sleep in adults.

NREM Sleep (con’t) Stages 3 and 4 are the deepest stages. Sleepers in these stages are not easily aroused. With age, the deeper stages of sleep are shorter Breathing is diminished during NREM sleep. It is irregular in the initial stages of NREM sleep but steadies during deeper stages. Muscle tone is diminished during NREM sleep, especially during the deeper stages.

REM Sleep The first cycle of REM sleep usually occurs 60 to 90 minutes after the onset of NREM sleep. REM sleep is believed to be the time when the sleeper dreams. The normal sleeper experiences four or five REM episodes each night. The initial episode is usually short (5 minutes), whereas the later episode is often much longer (60 minutes). Significant physiologic changes occur during REM sleep. Muscle tone is at a minimum, respiratory efforts are chaotic, and heart rate is irregular.

Sleep Related Breathing Disorders - Definitions Sleep apnea is defined as cessation of airflow for at least 10 seconds during sleep. Obstructive apnea is when the lack of breathing is caused by intermittent periods of upper airway obstruction. Central apnea is present when the patient temporarily stops breathing because of a loss in the drive to breathe. Hypopnea is defined as a significant decrease in ventilation during sleep enough to cause a greater than 4% drop in SaO2.

Sleep Related Breathing Disorders - Definitions Upper airway resistance syndrome (UARS) is present when the upper airway is abnormally narrowed during sleep but breathing is adequate to maintain normal gas exchange. The respiratory disturbance index (RDI) is defined as the total number of obstructive apneas, hypopneas, and central apneas per hour.

Sleep Disordered Breathing Severity An RDI of 5 to 20 = mild apnea; 20 to 40 = moderate apnea; more than 40 = severe apnea. The severity of the sleep disordered breathing problem is not just a function of the RDI but also the level of symptoms (excessive daytime sleepiness).

Sleep Disordered Breathing Severity - Children Abnormal if: –RDI > 1 –SpO 2 < 92% –End Tidal CO 2 > 53

Sleep Disordered Breathing Continuum The continuum ranges from mild snoring at one end to severe OSA at the other end. The goal of initial assessment is to find where the patient is on the continuum.

Sleep Disordered Breathing Continuum

Upper Airway Resistance Syndrome Patients with UARS usually have symptoms similar to those with OSA. Because UARS is difficult to diagnose, it is believed to be under-recognized and undertreated. Treatment of UARS is similar to that of OSA; the use of CPAP usually is effective. Main difference between UARS and OSA is the there is no hypoxia related to UARS.

Obstructive Sleep Apnea and Hypopnea OSA is the most commonly recognized sleep disordered breathing problem in adults. OSA is believed to be a result of collapse of the hypopharynx during the deeper stages of sleep as muscle tone is reduced. Obesity and anatomic defects of the upper airway contribute to the upper airway narrowing during sleep. Excessive daytime sleepiness is the most common symptom associated with OSA.

Obstructive Sleep Apnea and Hypopnea Bed partners of patients with OSA complain of hearing loud snoring during the night. The physical examination of the patient with OSA is often normal or minimally abnormal. OSA patients often have a large, thick neck, and a large tongue. Evidence of chronic hypoxemia may be seen in the physical examination; JVD and pedal edema suggest right heart failure due to cor pulmonale.

Children and Infants with Sleep Disorders Snoring is also the hallmark of OSA in children. Children with OSA may be sleepy or hyperactive. Children with OSA may have poor school performance, aggressive behavior, and social withdrawal. Children with attention deficit/hyperactivity disorder may have OSA as the underlying problem.

Central Sleep Apnea in Children In children central apnea may be caused by a number of factors; instability of the breathing control centers in the brain is a possible primary factor. The CSA patient usually has a normal body appearance and function.

SIDS and ALTEs SIDS has no known cause. SIDS is only one of many potential sleep- related breathing disorders in children. SIDS is the leading cause of death in children younger than 1 year of age; it has a peak onset between 2 and 4 months of age. OSA may be a predisposing factor in SIDS patients.

Assessment of Sleep – Related Breathing Disorders The primary tool used to assess patient with OSA is the polysomnogram (PSG). The PSG monitors EEG, Spo2, ECG, breathing rate and effort, chin EMG, and EOG. OSA is seen as periods of apnea with continued breathing effort. CSA is seen as periods of apnea caused by an intermittent lack of breathing effort.

Sleep Study

Assessment of Sleep – Related Breathing Disorders The multiple sleep latency test (MSLT) is performed to determine the level of daytime sleepiness in the patient. The time it takes for the patient to fall asleep during daytime naps is measured in the MSLT. Patients with excessive daytime sleepiness will have an abnormal MSLT and will have an average sleep latency during the MSLT of less than 5 to 8 minutes.

Sleep Study on Children

Summary RT’s Role OSA Symptoms Life threatening event CSA Mixed sleep apnea CPAP

Typical Sleep Lab

Sleep Study in Progress

Polysomnography

2 nd Polysomnography

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