Acronyms

There's a lot of acronyms and abbreviations associated with sleep apnea. The purpose of this list is to assist users in understanding the "alphabet soup" as well as understand the difference between similar terms (such as Bi-Flex and BiPAP and Bi-Level).

Alphabetical

A

• A-Flex - Respironics' name for exhalation pressure relief for their APAP
• AHI / A/HI - apnea hypopnea index
• AI - apnea index
• APAP - automatic positive airway pressure (also called Auto-CPAP, AutoPAP, AutoCPAP)
• ASV - Adaptive Servo Ventilator

B

• Bi-Flex - Respironic's name for exhalation pressure relief for BiPAP
• BiPAP - bilevel positive airway pressure (Respironics' brand of bilevel)
• BPAP - bilevel positive airway pressure
• BPM - beats or breaths per minute

C

• CA - Central Apnea or Clear Airway
• CAI - Central Apnea Index
• C-Flex - Respironic's name for exhalation pressure relief for CPAP
• cm / cmH2O - centimeters; unit of pressure used by xPAP machines; centimeter of water
• CO2 - carbon dioxide (not to be confused with carbon monoxide)
• COPD - chronic obstructive pulmonary disease
• CPAP - continuous positive airway pressure
• CSA - central sleep apnea
• CSR - Cheyne–Stokes respiration, (see also Periodic Breathing)

D

• DME - durable medical equipment; distributor of durable medical equipment; the same as HME (durable means non-disposable like xPAP machines)
• DAW - Dispense as Written. Instruction to dispense DME by brand and type exactly as prescribed.

E

• EDS - excessive daytime sleepiness; somnolence
• EEG - Electroencephalography (brain waves)
• EERS - Enhanced Expiratory Rebreathing Space (EERS)
• EMG - Electromyogram (muscle movement)
• EPAP - Expiratory (exhale) Positive Airway Pressure
• EPR - expiratory pressure relief (trade name by ResMed); Exhalation pressure relief

F

• FFM - full face mask mask
• FL - flow limitation

H

• H - Hypopnea
• HI - hypopnea index
• HME - home durable medical equipment; same as DME

I

• IPAP - Inspiratory (inhale) Positive Airway Pressure

L

• LL - Large Leak; a leak larger than the machine can compensate

N

• N-CPAP - nasal continuous airway pressure
• NREM - Non-rapid eye movement sleep

O

• O2 - oxygen
• OA - obstructive apnea
• OSA - obstructive sleep apnea
• OSCAR - OSCAR - Open Source CPAP Analysis Reporter

P

• PAP - positive airway pressure
• PB - Periodic breathing (note: this acronym exists predominantly within OSCAR only)
• PLMD - periodic limb movement disorder (body twitches during sleep, usually as the brain tries to wake you up to breathe)
• PLM - periodic limb movement (used on sleep reports with a number for how many occurred; part of the "arousal index")
• PS - pressure support; the difference in provided pressure between inspiration and expiration
• PSG - Polysomnography (sleep test)

R

• RDI - Respiratory disturbance index (RDI) (not the same as AHI)
• RE - See RERA (Respiratory Effort Related Arousal)
• REM - rapid eye movement (dream state sleep stage)
• RERA - Respiratory Effort Related Arousal (See RDI)
• RLS - restless leg syndrome ("twitchy" legs during the day, often preventing sleep)
• RPSGT - Registered Polysomnographic Technologist
• RT / RRT - registered respiratory therapist

S

• SA - sleep apnea
• SCC - Soft Cervical Collar (see also Positional Apnea and Soft Cervical Collar)
• SH - SleepyHead software

U

• UA - Unidentified Apnea
• UAI - Unidentified Apnea Events
• UPPP - Uvulopalatopharyngoplasty; also known as UP3

V

• Variable Breathing - Philips Respironics variable breathing algorithm seeks to develop a peak inspiratory flow trend on a 4 minute moving average, and measure the deviation above or below that trend. The system is designed to identify variable breathing and to turn over control of the pressure support system, from the auto CPAP controller to the Variable Breathing controller. Without figures, we don't know what that controller response is, but it seems if VB is detected while the pressure is steady, the VB controller will maintain that pressure, but if pressure was increasing before VB controller took control, the pressure is reduced up to 2-cm. Similarly if pressure was decreasing ahead of VB detection, the VB controller will in increase pressure up to 2-cm. The duration of VB controller action is 5 minutes unless VB is still detected.
• VPAP - variable positive airway pressure (Resmed's brand of bilevel)
• VS - Vibratory Snore (note: this acronym exists predominantly within OSCAR only)

X

• xPAP - any of the positive airway pressure machines

By Group

Machines and machine related

• SW - Displays the current software version.
• BID - Displays the boot loader ID.
• VID - Displays the variant ID.
• RID - Displays the regional variant ID.
• HID - Displays the humidifier software ID.

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