| positive-pressure respiration | A method of mechanical ventilation in which pressure is maintained to increase the volume of gas remaining in the lungs at the end of expiration, thus reducing the shunting of blood through the lungs and improving gas exchange. (12 Dec 1998) |
|---|---|
| positive-pressure respiration, intrinsic | Non-therapeutic positive end-expiratory pressure occurring frequently in patients with severe airway obstruction. It can appear with or without the administration of external positive end-expiratory pressure (positive-pressure respiration). It presents an important load on the inspiratory muscles which are operating at a mechanical disadvantage due to hyperinflation. Auto-peep may cause profound hypotension that should be treated by intravascular volume expansion, increasing the time for expiration, and/or changing from assist mode to intermittent mandatory ventilation mode. (12 Dec 1998) |
| positive rays | Those originating in a gas discharge tube and moving in a direction opposite to that of cathode ray's; made up of positively charged ions. Synonym: positive rays. (05 Mar 2000) |
| positive scotoma | A scotoma that is perceived as a black spot within the field of vision. (05 Mar 2000) |
| positive stain | <technique> Direct binding of a dye with a tissue component to produce contrast; in electron microscopy, heavy metals like uranyl and lead salts are used to bind to selective cell constituents to produce increased density to the electron beam, i.e., contrast. (05 Mar 2000) |
| positive strand RNA viruses | Class IV and VI viruses that have a single stranded RNA genome that can act as mRNA plus strand) and in which the virus RNA is itself infectious. Includes Picornaviridae, Togaviridae and Retroviridae. (18 Nov 1997) |
| positive supporting reactions | Consisting of those reflex muscular contractions whereby the body is supported against gravity; seen in an exaggerated form in the decerebrate animal, negative supporting reaction's, consisting of inhibition of the extensor muscles and unfixing of the joints which thus enable the limb to be flexed and moved into a new position. Synonym: supporting reflexes. (05 Mar 2000) |
| positive taxis | The attraction of protoplasm toward a stimulus. (05 Mar 2000) |
| positive thermotaxis | Attraction of a plant or animal to heat. (05 Mar 2000) |
| positive transference | Transference characterised by predominantly friendly, respectful, and positive feelings on the part of the patient toward the analyst. (05 Mar 2000) |
| intermittent positive-pressure breathing | Application of positive pressure to the inspiratory phase of spontaneous respiration. See: controlled mechanical ventilation (12 Dec 1998) |
| intermittent positive-pressure ventilation | Application of positive pressure to the inspiratory phase when the patient has an artificial airway in place and is connected to a ventilator. See: controlled mechanical ventilation (12 Dec 1998) |
| t-lymphocytopenia, idiopathic CD4-positive | Reproducible depletion of CD4+ lymphocytes below 300 per cubic millimeter in the absence of HIV infection or other known causes of immunodeficiency. This is a rare, heterogeneous syndrome and does not appear to be caused by a transmissible agent. (12 Dec 1998) |
| eyepiece, positive | <microscopy> An eyepiece in which the real image of the object is formed below the lower lens element, of the eyepiece. (05 Aug 1998) |
| false positive | <statistics> A test result that is read as positive when it is really negative. (27 Sep 1997) |