Respiratory Terms

Apnea - Literally means "no breath"; the cessation of airflow at the nostrils and mouth for at least 10 seconds

Apnea index (AI) - The number of apneas and hypopneas per hour. 5-20=mild, 21-50=moderate, above 51 severe

Arousal - Abrupt change from sleep to wakefulness, or from a "Deeper" stage of non-REM sleep to a "lighter" stage

Auto Adjusting Continuous Positive Airway Pressure Device (SmartPAP) (Auto-PAP) - A type of CPAP machine monitoring changes in breathing and compensates automatically by making appropriate adjustments in pressure

Bi-Level - Bi-level pressure device used to treat sleep apnea. The "bi" refers to two pressures: a lower pressure for exhalation and a higher pressure for inhalation. Bi-Level machines are more expensive than a standard CPAP, but some patients tolerate it better because they can exhale comfortably against the constant inhalation pressure.

Central Apnea - Absence of airflow and inspiratory effort; apnea caused by irregularity in the brain's control of breathing.

CPAP - Continuous Positive Airway Pressure; the device used to treat sleep apnea by sending positive airway pressure at a constant, continuous pressure to help keep an open airway, allowing the patient to breathe normally through his/her nose and airway.

CPAP Pressure - Pressure needed to maintain an open airway in a sleep apnea patient treated with CPAP, expressed in centimeters of water (cm H20). The positive pressure can range from 5 - 20 cm H2O. Different patients require different pressures. The value is determined in a CPAP titration study.

Deep Sleep - Refers to combined non-REM sleep stages 3 and 4 in sleep studies.

Diagnostic Sleep Study - Monitoring of several physiological activities in a sleeping individual. Usually performed to determine the absence or presence of a specific sleep disorder. The sleep study can occur in a sleep disorders center or in a patient's home with portable recording equipment.

EPAP - Expiratory Positive Airway Pressure. Pressure prescribed for the expiratory (breathing out) phase of an individual on Bi-level CPAP therapy for OSA (obstructive sleep apnea).

Epworth Sleepiness Scale - Index of sleep propensity during the day as perceived by patients, and derived from the answers to 8 questions.

Excessive Daytime Sleepiness or Somnolence (EDS) - Subjective report of difficulty in staying awake, accompanied by a ready entrance into sleep when the individual is sedentary.

Flattening Index - Number indicating the amount of airflow limitation caused by partial closure of the upper airway. 0.3 indicates an open airway, 0.15 is mildly obstructed, 0.1 is severely limited airflow, and 0.0 reflects a totally closed airway. Flattening Index is used to identify the condition known as Upper Airway Resistance Syndrome (UARS), and is continuously recorded in both diagnostic sleep studies and CPAP titrations.

Flow Limitation - The partial closure of the upper airway impeding the flow of air into the lungs.

Humidification - Moisture is added to the airflow as an adjunct to CPAP (Continuous Positive Airway Pressure) therapy in treating obstructive sleep apnea (OSA). Humidification can be added to the CPAP by diverting the airflow over or through a cool or heated water reservoir (humidifier) to prevent the upper airway from drying out.

Hypersomnia - Excessive, prolonged sleep.

Hyponea - Shallow breathing in which the air flow in and out of the airway is less than half of normal- usually associated with oxygen desaturation.

Hypoxemia - Abnormal lack of oxygen in the blood in the arteries.

Hypoxia - Deficiency of oxygen reaching the tissues of the body.

Insomnia - Complaint describing difficulty in sleeping.

IPAP - Inspiratory Positive Airway Pressure. Physician prescribed pressure for the inspiratory phase on a Bi-level CPAP device, used in the treatment of OSA.

Mixed (Sleep) Apnea - Interruption in breathing during sleep beginning as a central apnea then becoming an obstructive apnea.

Multiple Sleep Latency Test (MSLT) - a series of "nap tests" utilized in the assessment of excessive daytime sleepiness.

Narcolepsy - Sleep disorder characterized by excessive sleepiness, cataplexy, sleep paralysis, hypnogogic hallucinations, and an abnormal tendency to pass directly from wakefulness into REM sleep.

NREM or Non-REM sleep - Characterized by slower and larger brain waves and little or no dream behavior; quiet sleep, slow-wave sleep; approximately 80% of sleep.

Obstructive Apnea - Cessation of airflow (at least 10 seconds) in the presence of continued inspiratory effort; cessation of breathing during sleep, due to a mechanical obstruction, such as a semi-collapsed trachea, tongue relaxed to the back of the throat, or a large amount of tissue in the uvula area.

Obstructive Hypopnea - Periodic and partial closure of the throat during sleep resulting in reduced air exchange at the level of the mouth and/or nostril.

Oxygen Desaturation - Less than normal amount of oxygen carried by hemoglobin in the blood; values below 90% - 100%.

Polysomnogram (PSG) - Continuous and simultaneous recording of physiological variables during sleep, i.e., EEG, EOG, EMG (the three basic stage scoring parameters), EKG, respiratory air flow, respiratory excursion, lower limb movement, and other electrophysiological variables.

Prescribed CPAP Pressure - Pressure(s) or settings determined by a CPAP titration sleep study, which a physician prescribes for a patient's CPAP therapy machine.

RDI - Respiratory Disturbance Index, includes all respiratory events per hour.

REM Sleep, rapid eye movement sleep - Sleep characterized by the active brain waves, flitting motions of the eyes, and weakness of the muscles; most dreaming occurs in this stage, which accounts for about 20% of sleep in adults.

Sleep Apnea - Cessation of breathing for 10 or more seconds during sleep.

Sleep Cycle - Synonymous with NREM-REM cycle.

Sleep Disorders - Broad range of illness arising from many causes, including, dysfunctional sleep mechanisms, abnormalities in physiological functions during sleep, abnormalities of the biological clock, and sleep disturbances that are induced by factors extrinsic to the sleep process.

SmartPAP (Smart CPAP) - (Smart [Continuous] Positive Airway Pressure) Medical device used in the treatment of obstructive sleep apnea providing preset levels of continuous airflow, and automatically adjusting to keep the breathing passages open by sensing changes in airway integrity. The air flows from the device through a tube that connects to a nose or face mask.

Snoring - Noise produced primarily with inspiratory respiration during sleep owing to vibration of the soft palate and the pillars of the oropharyngeal inlet. Many snorers have incomplete obstruction of the upper airway, and may develop obstructive sleep apnea.

Titration - Progressive, stepwise increase in CPAP pressure applied during a polysomnogram to establish the optimal treatment pressure.

Upper Airway - Part of the respiratory anatomy that includes the nose, nostrils, sinus passages, septum, turbinates; the tongue, jaws, hard and soft palate, muscles of the tongue and throat, etc.

Uvulopalatopharyngoplasty (UPPP) - also abbreviated as UPP or UP3 this operation is performed on the throat to treat snoring and sleep apnea. UPPP is an accepted means of surgical treatment has a curative rate of less than 50%. Scientific evidence suggests that UPPP works best in retropalatal and combination retropalatal and retrolingual obstruction.