Understanding the Report

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The Ares report is similar to many conventional reports. The clinical history section will review the reason for the referral and pertinent physical information. There are several physical findings that show an increased probability of sleep disordered breathing. Three of the more important finding are 1) A neck size greater than 16.5 inches in males and 15 inches in females; 2)a BMI over 31; and 3) a score of >10 on the Epworth Sleepiness Scale. A history of snoring, witnessed apneas, hypertension, and diabetes increases the likelihood that the person may have sleep disordered breathing.

The two most common types of sleep apnea are obstructive sleep apnea (OSA) and central sleep apnea (CSA). Obstructive apnea is often a result of the collapse or blockage in the upper airway while maintaining effort where central apnea occurs when there is diminished effort due to the correct signals not reaching the muscles necessary for breathing. The two apneas are not exclusive and may occur in the same recording.

Apnea Hypopnea Index (AHI) is the total number of apneas and hypopneas per hour of sleep. Apneas are a more complete cessation of airflow while hypopneas are a partial cessation of airflow that must be associated with at least a 4% oxygen desaturation. Both events must be at least 10 seconds in duration.

Classification of Severity by AHI

  • An AHI of less than 5 apneas per hour is considered normal
  • An AHI in the 5-14 range is indicative of mild apnea
  • An AHI between 15 and 30 is considered moderate
  • An AHI over 30 is severe

Respiratory Disturbance Index (RDI) is the AHI plus respiratory events that are associated with at least a 1% oxygen desaturation and terminate with an arousal. The RDI is important when a patient may not meet the criteria for an apnea or hypopnea however they have more subtle sleep disordered breathing that may require treatment.

Oxygen desaturations are often associated with OSA and frequently seen in sleep disordered breathing. The SpO2 is seen as a percentage of Total Sleep Time however the patients overall health and presence of pulmonary disease may effect this number. It is important to note the frequency of the desaturations and the Min SpO2 with relationship to when these events occurred.

Snoring is measured in dB and as a percent of Total Sleep Time. Snoring is often heard in the supine position and may be associated with mild oxygen desaturations.

The Arousal index in conjunction with the RDI is often a good indicator of possible sleep fragmentation secondary to more subtle sleep disordered breathing. An arousal of 3-5 seconds often occurs following an apnea or hypopnea without the patient becoming fully awake. These arousals can be seen following loud snoring and inhibit the patient from cycling normally through all stages of sleep.

Body position during the night study is important to know. OSA is seen more frequently and sometimes exclusively seen while the patient is on their back and decreases when they turn to the side. or lie on their stomach.

Differentiation of NREM and REM sleep may also be helpful to know. There are people that will have OSA only in REM sleep when there is a further decrease in muscle tone. While there may be an increase in OSA in REM there is often a decrease in apnea and an increase in snoring in Stage 3 of NREM sleep.

Treatment Options

There is considerable evidence that sleep disordered breathing has many co-morbidities of which hypertension and type 2 diabetes are common. The increased risk of death associated with sleep apnea is over 46%. The most common treatment for OSA is PAP. With the increasing popularity and proven efficacy of auto adjusting PAP it may be no longer necessary to be seen at a sleep lab for a PAP titration study. The often overlooked choice of treatment of OSA is an oral appliance. There is evidence that the patient may be more compliant with this therapy than PAP. There are many surgical procedures for the treatment of OSA with many factors to consider. It is important that the patient is compliant with the therapy that is chosen.