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REM Density A function that expresses the frequency of eye movements per unit time during sleep stage REM
REM Sleep Latency The interval from sleep onset to the first appearance of stage REM sleep
REM Sleep Onset The beginning of the REM sleep episode as designated by the A Manual of Standardized Terminology; Better known as the R and K Manual
Rapid Eye Movement (REM) A sleep state that recurs cyclically several times during a normal period of sleep; Characterized by increased neuronal activity of the forebrain and midbrain, by depressed muscle tone, and esp. in humans by dreaming, rapid eye movements, and vascular congestion of the sex organs; Also called Paradoxical Sleep or Dream Sleep
Rapid Shallow Breathing Index (f/VT) Used to evaluate the adequacy of the patient’s spontaneous ventilation; Calculated as = f/VT = (Spont. Rate)/(Spont VE)
Resistance Impedance to flow in a tube or a conduit; Quantified as the ratio of the difference in pressure between the two points along a tube length divided by the volumetric flow of the fluid per unit of time (cmH20/L/sec)
Respiration The act of inhaling and exhaling air
Respiratory Disturbance Index (RDI) The number of apneas (obstructive, central or mixed) plus hypopneas per hour of total sleep time as determined by all-night polysomnography; Synonymous with apnea-hypopnea index
Respiratory Failure, Acute A clinical condition in which the patient’s arterial oxygen concentration drops markedly with or without an increase in carbon dioxide concentration
Respiratory Failure, Chronic Chronic inability of the respiratory system to maintain the function of oxygenating blood and remove carbon dioxide from the lungs
Respiratory Insufficiency Failure to adequately provide oxygen to cells of the body and to remove excess carbon dioxide from them
Response Time A measure (usually in msec) of the speed with which a mechanical ventilator can respond to a patient’s inspiratory effort and cycle into the inspiratory phase
Restless Leg Syndrome A discomfort in the legs which is relieved by moving or stimulating the legs; This feeling is difficult to describe and commonly referred to as a crawling, tingling or prickling sensation
Restrictive Lung Disease A broad category of disorders with widely variable etiologies; But all resulting in a reduction in lung volumes
Rhinitis Inflammation of the nasal mucous usually resulting in runny nose or congestion

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