| partial pressure | The pressure exerted by a single component of a mixture of gases, commonly expressed in mm Hg or torr; for a gas dissolved in a liquid, the partial pressure is that of a gas that would be in equilibrium with the dissolved gas. Formerly, symbolised by p, followed by the chemical symbol in capital letters (e.g., pCO2, pO2); now, in respiratory physiology, P, followed by subscripts denoting location and/or chemical species (e.g., PCO2, PO2, PaCO2). (05 Mar 2000) |
|---|---|
| mean arterial pressure | <cardiology, physiology> The average value for arterial pressure. Systolic pressure + diastolic pressure divided by 2. (27 Sep 1997) |
| central venous pressure | The venous pressure as measured at the right atrium, done by means of a catheter introduced through the median cubital vein to the superior vena cava, the distal end of the catheter being attached to a manometer. (12 Dec 1998) |
| cerebrospinal fluid pressure | Manometric pressure of the cerebrospinal fluid as measured by lumbar, cerebroventricular, or cisternal puncture. Within the cranial cavity it is called intracranial pressure. (12 Dec 1998) |
| cerebrospinal pressure | The pressure of the cerebrospinal fluid, normally 100 to 150 mm of water, relative to the ambient atmospheric pressure. (05 Mar 2000) |
| chromatography, high pressure liquid | Liquid chromatographic techniques which feature high inlet pressures, high sensitivity, and high speed. (12 Dec 1998) |
| root pressure | <botany> Pressure in the roots which, when the shoot is cut off, will cause liquid to ooze from the root stump, the mechanisms and tissues involved in this process are not clearly understood. (09 Oct 1997) |
| phrenic pressure test | Pressure is made on the phrenic nerve on each side, above the clavicles where the nerve passes over the scalenus anticus muscle; if pain is felt and the patient inclines his head to the painful side, the problem is in the pleural space; if his head does not incline to one side, the problem is in the abdominal cavity. (05 Mar 2000) |
| wedge pressure | The intravascular pressure reading obtained when a fine catheter is advanced until it completely occludes a small blood vessel or is sealed in place by inflation of a small cuff; commonly measured in the lung to estimate left atrial pressure. (05 Mar 2000) |
| pleural pressure | The pressure in the pleural space between the visceral and parietal pleurae. (05 Mar 2000) |
| coronary perfusion pressure | The pressure at which blood proceeds through the coronary circulation, mainly in diastole. (05 Mar 2000) |
| portal pressure | The venous pressure measured in the portal vein. (12 Dec 1998) |
| critical pressure | The minimum pressure required to liquefy a gas at the critical temperature. (05 Mar 2000) |
| postoperative pressure alopecia | Loss of hair over a circumscribed area usually on the posterior scalp, resulting from continuous pressure on the occiput in a lengthy operative procedure, or unconsciousness following a drug overdose. (05 Mar 2000) |
| pressure | 1. The act of pressing, or the condition of being pressed; compression; a squeezing; a crushing; as, a pressure of the hand. 2. A contrasting force or impulse of any kind; as, the pressure of poverty; the pressure of taxes; the pressure of motives on the mind; the pressure of civilization. "Where the pressure of danger was not felt." (Macaulay) 3. Affliction; distress; grievance. "My people's pressures are grievous." (Eikon Basilike) "In the midst of his great troubles and pressures." (Atterbury) 4. Urgency; as, the pressure of business. 5. Impression; stamp; character impressed. "All saws of books, all forms, all pressures past." (Shak) 6. <mechanics> The action of a force against some obstacle or opposing force; a force in the nature of a thrust, distributed over a surface, often estimated with reference to the upon a unit's area. Atmospheric pressure, Center of pressure, etc. See Atmospheric, Center, etc. <engineering> Back pressure, pressure which resists the motion of the piston, as the pressure of exhaust steam which does not find free outlet. Fluid pressure, pressure like that exerted by a fluid. It is a thrust which is normal and equally intense in all directions around a point. Pressure gauge, a gauge for indicating fluid pressure; a manometer. Origin: OF, fr. L. Pressura, fr. Premere. Source: Websters Dictionary (01 Mar 1998) |