LEVEL-3 HOME SLEEP TEST

What is a home sleep apnea test? (HSAT):

It’s a convenient,simple and affordable sleep apnea test that can be prescribed by a physician to diagnose Obstructive sleep apnea (OSA) in the comfort of your home. It is also called Limited channel sleep study/a portable sleep study or LEVEL-3 sleep study test.

What parameters Level-3 of the sleep study can record?

Level 3 devices record at least 3 channels of data (e.g., oximetry, airflow, respiratory effort).

Level-3 records the following parameters:

 El Shayeb et al., “Diagnostic Accuracy of Level 3 Portable Sleep Tests versus Level 1 Polysomnography for Sleep-Disordered Breathing.”

1. Cardiopulmonary parameters; two respiratory variables (e.g., effort to breathe, airflow), oxygen saturation, and a
2. Cardiac variable (e.g., heart rate or electrocardiogram).

Unlike level 1, level 3 testing cannot measure the duration of sleep, the number of arousals, or sleep stages, nor can it detect non-respiratory sleep disorders. 

Level 4 devices are also portable, but they capture less data — usually only 1 or 2 channels typically oxygen saturation and heart rate, or in some cases, just airflow. 

Indications for HSAT:

AASM-2007 Guidelines suggests that the HSAT or portable sleep test can be used as an alternate to PSG  for the diagnosis of OSA in the patients, if the following is indicated:

1. With high clinical possibility of moderate to severe OSA.

An increased risk of moderate to severe OSA is indicated by the presence of excessive daytime sleepiness and at least two of the following three criteria: 

1.1.  habitual loud snoring, 

1.2. witnessed apnea or gasping or choking,

1.3.  diagnosed hypertension.

2. For whom in lab PSG is not possible due to immobility or critical illness.

HSAT is not appropriate for the diagnosis of OSA in patients:        

• With significant comorbid medical conditions that may degrade its accuracy. i.e., non-obstructive sleep-disordered breathing (e.g., central sleep apnea, hypoventilation, and sleep-related hypoxemia):

For example-

1. advanced cardiopulmonary disease
2. potential respiratory muscle weakness due to neuromuscular conditions, 
3. history of stroke and 
4. chronic opiate medication use.

    Kundel and Shah, “Impact of Portable Sleep Testing.”

   BIBLIOGRAPHY:

    

   El Shayeb, Mohamed, Leigh-Ann Topfer, Tania Stafinski, Lawrence Pawluk, and Devidas Menon. “Diagnostic Accuracy of Level 3 Portable Sleep Tests versus Level 1 Polysomnography for Sleep-Disordered Breathing: A Systematic Review and Meta-Analysis.” CMAJ : Canadian Medical Association Journal 186, no. 1 (January 7, 2014): E25–51. https://doi.org/10.1503/cmaj.130952.

   Kundel, Vaishnavi, and Neomi Shah. “Impact of Portable Sleep Testing.” Sleep Medicine Clinics 12, no. 1 (March 2017): 137–47. https://doi.org/10.1016/j.jsmc.2016.10.006.

   
   

• Upon evaluation suspected of comorbid sleep disorders

1. disorders of central hypersomnolence, 
2. parasomnias- like sleepwalking, talking, nightmares, sleep-related movement disorders or 
3. severe insomnia.

With the screening of belonging to an asymptomatic population.

Environmental or personal factors that preclude the adequate acquisition and interpretation of data from HSAT.

If a single home sleep apnea test is negative, inconclusive or technically inadequate, polysomnography be performed for the diagnosis of OSA. 

Drawbacks of HSAT:

1. HSAT devices in comparison to attended studies raises the risk for technical failures due to a lack of real-time monitoring.
2. Level-3 can’t define sleep versus wake. 
3. Positive airway pressure (PAP) cannot be initiated during an HSAT, but can be initiated during a PSG if needed.
4. Measurement error is inevitable in HSAT, compared against PSG, as standard sleep staging channels are not typically monitored in HSAT (e.g., EEG, EOG, and EMG monitoring are not typically performed), which results in use of the recording time rather than sleep time to define the denominator of the respiratory event index (REI; the term used to represent the frequency of apneas and hypopneas derived from HSAT).
5. HSAT devices that use conventional sensors are unable to detect hypopneas only associated with cortical arousals, which are included in the recommended AHI scoring rule in the AASM Scoring Manual. 
6. Sensor dislodgement and poor quality signal during HSAT are additional contributors to the measurement error of the REI. 

All these factors can result in the underestimation of the “true” AHI, and may result in the need for repeated studies due to inadequate data for diagnosis.

Harms could result from misdiagnosis and subsequent inappropriate therapy or lack of therapy.

ADVANTAGES OF HSAT OVER PSG:

Use of HSAT may provide potential benefits to patients with suspected OSA. Such benefits could include 

• convenience, 
• comfort,
• increased access to testing, 
• decreased cost.
• HSAT can be performed in the home environment with fewer attached sensors during sleep. 
• May improve access to diagnostic testing in resource-limited settings, or when the patient is unable to leave the home or healthcare setting for testing. 

These benefits must be weighed against the potential for harm. If HSAT is used in the context described in the recommendations and remarks, the risk of harm is minimized and the probability of potential economic benefits increased.

How is HSAT done?

A single HSAT recording is conducted over at least one night.

A technically adequate the diagnostic test includes a minimum of  4 hours of technically adequate oximetry and flow data, obtained during a recording attempt that encompasses the habitual sleep period.

Devices available with us:

1. Alice night one
2. Apnea link

The device and Its sensors (pulse-oximeter, nasal prongs, chest belt with the device in the centre to connect all the channels) have to be connected 5 minutes before you sleep and then to be removed in the morning on waking up.

These should not be removed if you wake up in between for a brief period in the night for any reason like drinking water or urination.

After the completion of the test, the report is generated by the sleep technologist and approved by a physician.

CONCLUSION:

HSAT is a cost-effective, convenient, portable sleep study test, done at the comfort of the home setting. When prescribed for the appropriate patients, it can be of greater use and help to establish the diagnosis of OSA and treat them accordingly by giving appropriate therapy.

HOME SLEEP TEST

3 min 49 sec read

By Dr.Manvir Bhatia

Garima Sharma