| O2 | Oxygen |
| O2 | Chemical symbol for oxygen. Criterion lowest percent O2 saturation: Greater than 85%=mild 80% to 85%=moderate less than 80%=severe. |
| Obesity-Hypoventilation Syndrome | Term applied to obese individuals hypoventilating during wakefulness. |
| 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 back of the throat or a large among 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. |
| Obstructive sleep apnea or OSA | A sleep related breathing disorder that involves repeated episodes of hypopnea and apnea despite an ongoing respiratory effort. It occurs when the muscles relax during sleep causing soft tissue in the back of the throat to collapse and block the upper airway. |
| OBSTRUCTIVE SLEEP APNOEA (OSA) | Episodes of stopping breathing at night due to obstruction of the upper airway from narrowing during sleep. Produces sleep disruption and the daytime consequence of excessive sleepiness. |
| OCD | Obsessive Compulsive Disorder |
| ODI | Oxygen desaturation index |
| OLP | Online Psych |
| Ondine's Curse | The respiratory center in the brain is unable to stimulate breathing in response to an increased amount of carbon dioxide in the blood. Ondine's Curse or central alveolar hypoventilation typically worsens during sleep. |
| Optimum Sleep | Average amount of sleep needed every night by an individual. |
| OSA | Obstructive sleep apnea |
| OSA | Obstructive Sleep Apnea |
| OSAS | Obstructive sleep apnea syndrome |
| OTRIVINE | Nasal spray to reduce congestion. Can only be used for up to five nights consecutively: therefore of most use during a cold. Can be obtained over the counter without prescription. |
| Overnight sleep study | A polysomnogram or Type 1 sleep study. It is the standard method of detecting sleep disorders and evaluating treatments in children and adults. You stay in a private room that often has the comforts of a hotel room. As you sleep electrodes and sensors collect information such as airflow brain activity (EEG) respiratory effort eye movements (EOG) leg movements (EMG) blood oxygen saturation and unusual behavior. |
| Oximeter | A small device that provides continuous monitoring of your blood oxygen saturation. It can be worn on the ear but most often is placed on a fingertip. |
| OXIMETER (ox-im-eater) | Monitoring device that continuously measures the level of oxygen (oxygen saturation) in the blood by measuring its colour: usually done with a clothes peg like clip on the finger or ear. A common way to analyse the overnight tracing is to count the number of dips in oxygen. |
| Oximeter (Pulse) | Gives estimates of arterial oxyhemoglobin saturation (SaO2) by utilizing selected wavelengths of light to non invasively determine the saturation of oxyhemoglobin (SpO2). |
| Oximetry (Pulse) | Continuous monitoring of oxygen saturation of arterial blood from a pulse oximeter; the sensor is usually attached to the finger. |
| Oxygen Desaturation | Less than normal amount of oxygen carried by hemoglobin in the blood; values below 90% are considered abnormal |
| Oxygen Saturation | measure of oxygen carried by hemoglobin in the blood. Normal values 90% - 100%. |
