top of page
  • APNOEA
    A pause in breathing; conventionally more than 10 seconds. From the Greek a (without) pnoea (breath).
  • APNOEA HYPOPNOEA INDEX (AHI)
    The Apnea–Hypopnoea Index or Apnoea–Hypopnoea Index (AHI) is an index used to indicate the severity of sleep apnoea. It is represented by the number of apnoea and hypopnoea events per hour of sleep. The apnoeas (pauses in breathing) must last for at least 10 seconds and be associated with a decrease in blood oxygenation.
  • AUTO CPAP MACHINE (APAP)
    A clever computerised CPAP machine that adjusts its pressure automatically to match the minimum pressure required to keep the airway open. It works very well for some people, though others find the small delay in reaching the right pressure troublesome.
  • BODY MASS INDEX (BMI)
    Body Mass Index (BMI) is an indication of a healthy body in relation to weight. A healthy BMI is between 19 and 25, 25-30 is overweight, 30-35 is obese and over 35 morbidly obese. Being overweight is a common risk factor for OSA.
  • CENTRAL SLEEP APNOEA (CSA)
    Episodes of stopping breathing, not due to obstruction of the upper airway, but due to the brain simply failing to ask for a breath. Much less common than obstructive sleep apnoea. Treatment tends to focus on treating the underlying cause if this can be identified, for example, heart failure.
  • CHEYNE-STOKES-BREATHING
    Breathing that cycles up and down, also know as periodic breathing. Found in people with heart failure and neurological problems.
  • CONTINUOUS POSITIVE AIRWAY PRESSURE (CPAP)
    The process of delivering a continuously raised airway pressure from a small electric pump, via a mask on or under the nose or over the nose and mouth.
  • CPAP Masks
    Mask – Consisting of four main types, nasal pillows, nasal mask, hybrid and full-face mask Nasal Pillows – sits under the nose with short pillow protrusions into the nasal passages, that inflate slightly due to the slight increase in air pressure once the pump starts Nasal Mask – fits over the nose on a cushion, that is sealed by the slight increase in air pressure once the pump starts Full Face Mask – Covers the nose and mouth on a cushion that is sealed by the slight increase in air pressure once the pump starts. Hybrid Full Mask- Covers the nose and mouth on a cushion that is sealed by the slight increase in air pressure once the pump starts. However, compared to a full face mask, the mask fits under the nose rather than over the bridge of the nose.
  • DESATURATIONS (SEE ALSO HYPOXIC DIPS)
    The falls in oxygen levels, seen on the oximeter, that usually accompany apnoeas. Also known as desaturations, because when it is not hypoxic the blood is described as fully saturated with oxygen.
  • EPWORTH SLEEPINESS SCALE (ESS)
    Eight questions asking about tendency to drop off at inappropriate times, used to gauge how sleepy someone is. A score of 0-10 is normal, 11-15 possibility of mild to moderate OSA and 16 and over, severe OSA or narcolepsy.
  • HUMIDIFIER
    A CPAP Heated Humidifier houses a water chamber, which it heats to moisturise the air provided by your machine. They are ideal for those who find the machine leaves them waking with a dry mouth, sore nasal passages or simply find the air cold and therefore uncomfortable. Also assists asthmatics during periods of high pollen count.
  • HYPERCAPNIA
    A raised level of carbon dioxide in the blood. This is the gas normally breathed out which will rise if breathing is inadequate. It may be measured by taking an arterial or capillary blood sample
  • HYPERSOMNOLENCE
    Technical expression for excessive sleepiness.
  • HYPOPNOEA
    A period of under breathing, conventionally for more than 10 seconds.
  • HYPOXIA
    When the body is short of oxygen and therefore the level in the blood falls.
  • HYPOXIC DIPS
    The falls in oxygen levels, seen on the oximeter, that usually accompany apnoeas. Also known as desaturations, because when it is not hypoxic the blood is described as fully saturated with oxygen.
  • INSOMNIA
    Being awake when you want to be asleep. Often thought of as a problem, but may not be. Common if people try to spend too long in bed.
  • MICRO AROUSALS
    Very brief “awakenings” or lightening of sleep, perhaps only seen when the brain waves (EEG) are being monitored.
  • NOCTURIA
    Excessive urine production at night. Seen in sleep apnoea quite often.
  • NOCTURNAL HYPOVENTILATION
    Underbreathing at night.
  • OBSTRUCTIVE SLEEP APNOEA (OSA)
    A relatively common condition where the walls of the throat relax and narrow during sleep, interrupting normal breathing. This may lead to regularly interrupted sleep, which can have a big impact on quality of life and increases the risk of developing certain conditions.
  • OBSTRUCTIVE SLEEP APNOEA SYNDROME (OSAS)
    Obstructive sleep apnoea syndrome defines patients with repetitive apnoeas and symptoms of sleep fragmentation with excessive sleepiness (BTS definition)
  • OXYGEN DESATURATION INDEX (ODI)
    The oxygen desaturation index (ODI) is the number of times per hour of sleep that the blood’s oxygen level drops by a certain degree from baseline. The ODI is typically measured as part of standard sleep studies, such as a diagnostic polysomnogram, home sleep apnoea testing, or with overnight oximetry.
  • PERIODIC LIMB MOVEMENT SYNDROME (PMLS)
    A condition where the legs move every 40 seconds or so, producing brief arousals. Another cause of daytime sleepiness. Sometimes associated with Restless Legs symptoms. Distinct from myoclonus (an involuntary muscle jerk experienced by many people as they drop off to sleep.
  • POLYSOMNOGRAPHY
    Simply means a recording of lots of things during sleep. Has come to mean recording at least EEG, EMG and EDG all night.
  • POSITIONAL SLEEP APNOEA
    Positional Sleep Apnoea – When sleeping on your back, there is a tendency for the tongue to move even further back under the influence of gravity. This can cause Obstructive Sleep Apnoea (OSA) or increase its (AHI) severity in a patient diagnosed with OSA. This is why clinicians recommend sleeping on your side if you suffer from OSA, as the gravitational effect is mitigated.
  • RESTLESS LEG SYNDROME
    Also known as PLMS and nocturnal myoclonus. An uncomfortable creepy-crawly sensation of the legs and an irresistible urge to move them, experienced mostly in the evening and at night. Another cause of daytime sleepiness.
  • SLEEP STAGES
    Sleep is conventionally divided into five stages. Four of these are called non-REM sleep, the other is REM (or Rapid Eye Movement) sleep. REM sleep is when we dream, and the brain is virtually awake. Non- REM sleep is three stages, stage 1 (N1), Stage 2 (N2) and stage 3 (N3). Stages 1 and 2 are the lighter forms of sleep and stage is the deeper refreshed sleep called Slow Wave Sleep (SWS).
bottom of page