| NPV | negative predictive value; pressure value; negative pressure ventilation; net present value; nuclear... |
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| OAP | Office of Adolescent Pregnancy; old age pension, old age pensioner; ophthalmic artery pressure; oste... |
| OP | occipitoparietal; occipitoposterior; occiput posterior; octapeptide; olfactory peduncle; opening pre... |
| OPP | osmotic pressure of plasma; oxygen partial pressure |
| pa-pv | pulmonary arterial pressure-pulmonary venous pressure |
| pressure gangrene | <dermatology> A chronic ulcer that appears in pressure areas in debilitated patients confined to bed or otherwise immobilised, due to a circulatory defect from the enhanced tissue pressure in high-contact areas, often occurring over a bony prominence (for example sacral decubitus). (27 Sep 1997) |
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| pressure, intraocular | The pressure created by the continual renewal of fluids within the eye. The intraocular pressure is increased in glaucoma. In acute angle-closure glaucoma, the intraocular pressure rises because the canal into which the fluid in the front part of the eye normally drains is suddenly blocked. In chronic glaucoma, there is a gradual imbalance between the production and removal (resorption) of the fluid in the back part of the eye (with supply exceeding demand). (12 Dec 1998) |
| pressure palsy | Paralysis due to compression of a nerve, nerve trunk, or spinal cord. Synonym: pressure palsy. (05 Mar 2000) |
| pressure paralysis | Paralysis due to compression of a nerve, nerve trunk, or spinal cord. Synonym: pressure palsy. (05 Mar 2000) |
| pressure plethysmograph | A plethysmograph applied to part of the body, e.g., a limb segment, and arranged so that volume is measured during temporary application of sufficient pressure to the part to empty its blood vessels, a body plethysmograph in which changes of body volume are measured in terms of the consequent changes in air pressure in the body plethysmograph. Volume-displacement plethysmograph, a plethysmograph, usually a body plethysmograph, in which changes in volume displace a corresponding volume into or out of a very compliant measuring device, such as a Krogh spirometer or integrating flowmeter. (05 Mar 2000) |
| pressure pneumothorax | A variety of spontaneous pneumothorax in which air enters the pleural cavity and is trapped during expiration; intrathoracic pressure builds to values higher than atmospheric pressure, compresses the lung, and may displace the mediastinum and its structures toward the opposite side, with consequent disadvantageous effects on blood flow. Synonym: pressure pneumothorax, valvular pneumothorax. (05 Mar 2000) |
| pressure point | A cutaneous locus having pressure-sensitive elements which when compressed, pressure is appreciated. (05 Mar 2000) |
| pressure reversal | Cessation of anaesthesia by hyperbaric pressure; of major importance in understanding the mode of action of anaesthetics. (05 Mar 2000) |
| pressure sense | The faculty of discriminating various degrees of pressure on the surface. Synonym: baresthesia, piesesthesia, weight sense. (05 Mar 2000) |
| pressure sore | <dermatology> A chronic ulcer that appears in pressure areas in debilitated patients confined to bed or otherwise immobilised, due to a circulatory defect from the enhanced tissue pressure in high-contact areas, often occurring over a bony prominence (for example sacral decubitus). (27 Sep 1997) |
| pressure stasis | Cyanotic asphyxia due to trauma; the extravasation of blood into the skin and conjunctivae, produced by a sudden mechanical increase in venous pressure, analogous to the Rumpel-Leede test; it is common in those who have been hanged, and is seen occasionally in crush injuries. Synonym: pressure stasis. (05 Mar 2000) |
| pressure urticaria | Urticaria of unknown aetiology occurring after local pressure on the skin. (05 Mar 2000) |
| pressure-volume index | Method of evaluating the cerebrospinal fluid hydrodynamics. (05 Mar 2000) |
| high blood pressure | <cardiology> Persistently high arterial blood pressure. Hypertension may have no known cause (essential or idiopathic hypertension) or be associated with other primary diseases (secondary hypertension). This condition is considered a risk factor for the development of heart disease, peripheral vascular disease, stroke and kidney disease. (29 Sep 1997) |
| high-pressure | 1. Having or involving a pressure greatly exceeding that of the atmosphere; said of steam, air, water, etc, and of steam, air, or hydraulic engines, water wheels, etc. 2. Urgent; intense; as, a high-pressure business or social life. High-pressure engine, an engine in which steam at high pressure is used. It may be either a condensing or a noncondensing engine. Formerly the term was used only of the latter. See Steam engine. Source: Websters Dictionary (01 Mar 1998) |