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pressure

 (P) [presh´ur]
force per unit area.
arterial pressure (arterial blood pressure) blood pressure (def. 2).
atmospheric pressure the pressure exerted by the atmosphere, usually considered as the downward pressure of air onto a unit of area of the earth's surface; the unit of pressure at sea level is one atmosphere. Pressure decreases with increasing altitude.
barometric pressure atmospheric p.
blood pressure
2. pressure of blood on walls of any blood vessel.
capillary pressure the blood pressure in the capillaries.
central venous pressure see central venous pressure.
cerebral perfusion pressure the mean arterial pressure minus the intracranial pressure; a measure of the adequacy of cerebral blood flow.
cerebrospinal pressure the pressure of the cerebrospinal fluid, normally 100 to 150 mm Hg.
continuous positive airway pressure see continuous positive airway pressure.
filling pressure see mean circulatory filling pressure.
high blood pressure hypertension.
intracranial pressure see intracranial pressure.
intraocular pressure the pressure exerted against the outer coats by the contents of the eyeball.
intrapleural pressure (intrathoracic pressure) pleural pressure.
intrinsic positive end-expiratory pressure elevated positive end-expiratory pressure and dynamic pulmonary hyperinflation caused by insufficient expiratory time or a limitation on expiratory flow. It cannot be routinely measured by a ventilator's pressure monitoring system but is measurable only using an expiratory hold maneuver done by the clinician. Its presence increases the work needed to trigger the ventilator, causes errors in the calculation of pulmonary compliance, may cause hemodynamic compromise, and complicates interpretation of hemodynamic measurements. Called also auto-PEEP and intrinsic PEEP.
maximal expiratory pressure maximum expiratory pressure.
maximal inspiratory pressure the pressure during inhalation against a completely occluded airway; used to evaluate inspiratory respiratory muscle strength and readiness for weaning from mechanical ventilation. A maximum inspiratory pressure above −25 cm H2O is associated with successful weaning.
maximum expiratory pressure (MEP) a measure of the strength of respiratory muscles, obtained by having the patient exhale as strongly as possible against a mouthpiece; the maximum value is near total lung capacity.
maximum inspiratory pressure (MIP) the inspiratory pressure generated against a completely occluded airway; used to evaluate inspiratory respiratory muscle strength and readiness for weaning from mechanical ventilation. A maximum inspiratory pressure above −25 cm H2O is associated with successful weaning.
mean airway pressure the average pressure generated during the respiratory cycle.
mean circulatory filling pressure a measure of the average (arterial and venous) pressure necessary to cause filling of the circulation with blood; it varies with blood volume and is directly proportional to the rate of venous return and thus to cardiac output.
negative pressure pressure less than that of the atmosphere.
oncotic pressure the osmotic pressure of a colloid in solution.
osmotic pressure the pressure required to stop osmosis through a semipermeable membrane between a solution and pure solvent; it is proportional to the osmolality of the solution. Symbol π.
partial pressure the pressure exerted by each of the constituents of a mixture of gases.
peak pressure in mechanical ventilation, the highest pressure that occurs during inhalation.
plateau pressure in mechanical ventilation, the pressure measured at the proximal airway during an end-inspiratory pause; a reflection of alveolar pressure.
pleural pressure the pressure between the visceral pleura and the thoracic pleura in the pleural cavity. Called also intrapleural or intrathoracic pressure.
positive pressure pressure greater than that of the atmosphere.
positive end-expiratory pressure (PEEP) a method of control mode ventilation in which positive pressure is maintained during expiration 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. A PEEP higher than the critical closing pressure prevents alveolar collapse and can markedly improve the arterial Po2 in patients with a lowered functional residual capacity, as in acute respiratory failure.
Effects of the application of positive end-expiratory pressure (PEEP) on the alveoli. A, Atelectatic alveoli before PEEP application. B, Optimal PEEP application has reinflated alveoli to normal volume. C, Excessive PEEP application overdistends the alveoli and compresses adjacent pulmonary capillaries, creating dead space with its attendant hypercapnia. From Pierce, 1995.
pulmonary artery wedge pressure (PAWP) (pulmonary capillary wedge pressure (PCWP)) intravascular pressure, reflecting the left ventricular end diastolic pressure, measured by a swan-ganz catheter wedged into a small pulmonary artery to block the flow from behind.
pulse pressure the difference between the systolic and diastolic pressures. If the systolic pressure is 120 mm Hg and the diastolic pressure is 80 mm Hg, the pulse pressure is 40 mm Hg; the normal pulse pressure is between 30 and 40 mm Hg.
urethral pressure the pressure inwards exerted by the walls of the urethra, which must be counteracted in order for urine to flow through; see also urethral pressure profile.
venous pressure the blood pressure in the veins; see also central venous pressure.
water vapor pressure the tension exerted by water vapor molecules, 47 mm Hg at normal body temperature.
wedge pressure blood pressure measured by a small catheter wedged into a vessel, occluding it; see also pulmonary capillary wedge pressure and wedged hepatic vein pressure.
wedged hepatic vein pressure the venous pressure measured with a catheter wedged into the hepatic vein. The difference between wedged and free hepatic vein pressures is used to locate the site of obstruction in portal hypertension; it is elevated in that due to cirrhosis, but low in cardiac ascites or portal vein thrombosis.

pres·sure (P, P),

(presh'ŭr),
1. A stress or force acting in any direction against resistance.
2. physics, physiology the force per unit area exerted by a gas or liquid against the walls of its container or that would be exerted on a wall immersed at that spot in the middle of a body of fluid:The pressure can be considered either relative to some reference pressure, such as that of the ambient atmosphere (imagined as on the other side of the wall) or in absolute terms (relative to a perfect vacuum).
[L. pressura, fr. premo, pp. pressus, to press]

pressure

/pres·sure/ (P ) (presh´er) force per unit area.
arterial pressure  blood p. (2).
blood pressure 
1. the pressure of blood against the walls of any blood vessel.
2. the pressure of blood on the walls of the arteries, dependent on the energy of the heart action, elasticity of the arterial walls, and volume and viscosity of the blood; the maximum or systolic pressure occurs near the end of the stroke output of the left ventricle, and the minimum or diastolic late in ventricular diastole.
central venous pressure  (CVP) 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.
cerebrospinal pressure  the pressure or tension of the cerebrospinal fluid, normally 100–150 mm. as measured by the manometer.
detrusor pressure  the pressure exerted inwards by the detrusor urinae muscles of the bladder wall.
diastolic pressure , diastolic blood pressure see blood p.
end-diastolic pressure  the pressure in the ventricles at the end of diastole, usually measured in the left ventricle as an approximation of the end-diastolic volume, or preload.
intracranial pressure  (ICP) pressure of the subarachnoidal fluid.
intraocular pressure  the pressure exerted against the outer coats by the contents of the eyeball.
intravesical pressure  the pressure exerted on the contents of the urinary bladder; the sum of the intra-abdominal pressure from outside the bladder and the detrusor pressure.
maximum expiratory pressure  (MEP) a measure of the strength of respiratory muscles, obtained by having the patient exhale as strongly as possible against a mouthpiece; the maximum value is near total lung capacity.
maximum inspiratory pressure  (MIP) a measure of the strength of respiratory muscles, obtained by having the patient inhale as strongly as possible with the mouth against a mouthpiece; the maximum value is near the residual volume.
mean arterial pressure  (MAP) the average pressure within an artery over a complete cycle of one heartbeat.
mean circulatory filling pressure  a measure of the average (arterial and venous) pressure necessary to cause filling of the circulation with blood; it varies with blood volume and is directly proportional to the rate of venous return and thus to cardiac output.
negative pressure  pressure less than that of the atmosphere.
oncotic pressure  the osmotic pressure due to the presence of colloids in solution.
osmotic pressure  the pressure required to prevent osmosis through a semipermeable membrane between a solution and pure solvent; it is proportional to the osmolality of the solution. Symbol π.
partial pressure  the pressure exerted by each of the constituents of a mixture of gases.
positive pressure  pressure greater than that of the atmosphere.
positive end-expiratory pressure  (PEEP) a method of mechanical ventilation in which pressure is maintained to increase the volume of gas left in the lungs at the end of exhalation, reducing shunting of blood through the lungs and improving gas exchange.
pulmonary artery wedge pressure  (PAWP), pulmonary capillary wedge pressure (PCWP) intravascular pressure as measured by a catheter wedged into the distal pulmonary artery ; used to measure indirectly the mean left atrial pressure.
pulse pressure  the difference between systolic and diastolic pressures.
systolic pressure , systolic blood pressure see blood p.
Valsalva leak point pressure  the amount of pressure on the bladder by a Valsalva maneuver at which leakage of urine occurs; a measure of strength of the urethral sphincters.
venous pressure  the pressure of blood in the veins.
wedge pressure  blood pressure measured by a small catheter wedged into a vessel, occluding it, e.g., pulmonary capillary wedge p.
wedged hepatic vein pressure  the venous pressure measured with a catheter wedged into the hepatic vein; used to locate the site of obstruction in portal hypertension.

pressure (P)

[presh′ər]
Etymology: L, premere, to press
a force, or stress, applied to a surface by a fluid or an object, usually measured in units of mass per unit of area, such as pounds per square inch. Other units are mm Hg, bar, atm.

pressure

Vox populi A force or stress applied to a suface by a fluid or object, and measured in units of mass per unit area. See Blood pressure, Continuous positive airway pressure, Coronary perfusion pressure, End-diastolic pressure, End-systolic pressure, Intracranial pressure, Intraocular pressure, Intrauterine pressure, Negative pressure, Negative end-expiratory pressure, Oncotic pressure, Osmotic pressure, PEEP, Pulmonary-capillary pressure, Transpulmonary pressure, Wedge pressure.

pres·sure

(presh'ŭr)
1. A stress or force acting in any direction against resistance.
2. physics, physiology The force per unit area exerted by a gas or liquid against the walls of its container or that would be exerted on a wall immersed at that spot in the middle of a body of fluid. The pressure can be considered either relative to some reference pressure, such as that of the ambient atmosphere (gauge pressure), or relative to a perfect vacuum (absolute pressure).
[L. pressura, fr. premo, pp. pressus, to press]

pressure

force divided by the area over which the force acts. Measured in pascals (Pa) or newtons per square metre (N.m-2). barometric pressure the pressure due to the column of atmosphere above an object or body (measured also in millimetres of mercury or millibars).

pressure

force per unit area exerted by a gas/liquid against the walls of its container, or a solid (e.g. foot) against the contact/support surface
  • blood pressure; BP pressure/tension of arterial blood, maintained by ventricular contraction, arteriolar and capillary resistance, arterial wall elasticity and circulating blood viscosity and volume; recorded (using sphygmomanometer and stethoscope or automated blood pressure recorder) by occluding the brachial artery at heart level; as cuff pressure is reduced, blood flow gradually restores; systolic and diastolic BP are noted (Korotkoff's sounds) in mmHg, and expressed as a ratio (systolic/diastolic); normal adult BP = 120/80mmHg; BP is often raised in older people and in diabetes (see antihypertensive agents; hypertension)

  • diastolic BP lowest value (in mmHg) of recorded BP and minimum pressure at which the arterial system operates; occurs at the point of heart muscle relaxation; noted as the last audible arterial bruit (when impedance to blood flow [imposed by the deflating sphygmomanometer cuff] has fully reduced), and arterial blood flow is no longer restricted, and therefore silent; see pressure, systolic BP

  • partial pressure pressure exerted by a gas in a liquid, e.g. pressure of oxygen in blood (P O2); see pulse oximeter

  • systolic BP highest value (in mmHg) of recorded BP and maximum pressure at which the arterial system operates; occurs at the point of heart muscle contraction; noted as the first audible arterial bruit (when impedance to blood flow [imposed by the fully inflated sphygmomanometer cuff] has reduced [following opening of the pressure valve screw]) and arterial flow can just occur, at maximal cardiac contraction

pressure 

The force per unit area exerted by a gas or liquid over a surface in a direction perpendicular to that surface. The SI unit of pressure is the pascal (Pa), although blood pressure and intraocular pressure remain specified in the non-SI unit millimetres of mercury (mmHg). See oxygen permeability.
blood pressure See sphygmomanometer.
equivalent oxygen pressure See equivalent oxygen pressure.
intraocular pressure (IOP) The pressure within the eyeball occurring as a result of the constant formation and drainage of the aqueous humour. This is measured by means of a manometer. What is actually measured in the human eye is the ocular tension by means of a tonometer. This is an indirect measure of the IOP as it depends on the thickness and rigidity of the tunics of the eye besides the IOP. Both terms, intraocular pressure and ocular pressure, are usually regarded as synonymous. Normal IOP is usually considered to be between 11 mmHg and 21 mmHg. However, there may be cases of glaucoma with lower IOP than 21 mmHg and there are also many normal cases with IOP greater than 21 mmHg. There is a slight increase in IOP with age (about 2 mmHg), in the morning as compared to the evening (about 3-4 mmHg), in the supine position as compared to the sitting position (about 3-4 mmHg), and a decrease during accommodation (about 4 mmHg). See in intraocular pressure diurnal variations; glaucoma; aqueous humour; ocular hypertension; ocular hypotony; scleral indentation; Imbert-Fick law; ocular rigidity; differential intraocular pressure test; provocative test; tonometer.
osmotic pressure The pressure required to stop the movement of water through a semipermeable membrane (e.g. corneal endothelium) from one solution of a given concentration to another of a different concentration. When the concentration of the solution on both sides of the membrane is equal, i.e. at equilibrium, the pressure of water on both sides of the membrane will be equal to the osmotic pressure and the movement of water will stop. The more concentrated the solution, the greater the osmotic pressure. See osmosis; hypertonic solution; hypotonic solution; isotonic solution.
pulse pressure See sphygmomanometer.

pres·sure

(P) (presh'ŭr)
Stress or force acting in any direction against resistance.
[L. pressura, fr. premo, pp. pressus, to press]

pressure,

n a stress or strain that may occur by compression, pull, or thrust; an applied force.
pressure area,
pressure atrophy,
pressure, biting,
n the actual or potential power used in bringing the teeth into contact. See also pressure, occlusal.
pressure, blood,
pressure, deeper,
n a pressure to the body–in excess of that which stimulates Meissner's corpuscles, Merkel's disks, or the hair receptors of light touch–that stimulates the deeper receptors such as Pacini's corpuscles. These latter deep-pressure perception organs lie in the inner layers of the dermis and in the muscle and tendon groups.
pressure, equalization of,
n the act of distributing pressure evenly.
pressure, hand,
n force applied by an instrument held in the hand.
pressure, hydraulic,
n pressure transmitted by a liquid trapped between the tooth and a restoration being cemented.
pressure, hydrostatic,
n the pressure in the circulatory system exerted by the volume of blood when it is confined in a blood vessel. The hydrostatic pressure, coupled with the osmotic pressure within a capillary is opposed by the hydrostatic and osmotic pressure of the surrounding tissues. Fluids flow from the higher pressure areas to the lower pressure areas.
pressure, intrapleural,
n pressure within the pleura.
pressure, occlusal,
n any force exerted on the occlusal surfaces of teeth. See also force, occlusal and load, occlusal.
pressure, osmotic,
n the stress that develops when solutions containing different concentrations of solute in a common solvent are separated by a membrane that is permeable to the solvent but not the solute.
pressure, partial,
n the pressure exerted by each of the constituents of a mixture of gases.
pressure, pulse,
n the difference between systolic and diastolic pressure.
pressure sensibility,
n the ability to detect light touch and deep pressure. See also corpuscle, Meissner's; corpuscle, Merkel's; and corpuscle, Pacini's.
pressure sore,
n a decubitus ulcer caused when the bony protuberances of the body are subjected to chronic pressure from the weight of the body without breaks.

pressure

stress or strain, by compression, expansion, pull, thrust or shear.

arterial pressure
the blood pressure in the arteries.
atmospheric pressure
the pressure exerted by the atmosphere, about 15 lb per square inch (2.17 kPa) at sea level.
capillary pressure
the blood pressure in the capillaries.
central venous pressure (CVP)
see central venous pressure.
cerebrospinal pressure
the pressure of the cerebrospinal fluid, normally 100 to 150 mmHg.
diastolic pressure
the lowest pressure recorded in the arterial blood pressure cycle. Represents the minimal pressure in the left ventricle which can maintain its ejection phase. See also blood pressure.
pressure gauge
a device attached to the outlet of gas tanks to measure internal pressure which indicates the quantity of gas remaining.
pressure gradient
the rate of increase (or decrease) in the magnitude of the pressure being measured.
intracranial pressure (ICP)
see intracranial pressure.
intraocular pressure (IOP)
the pressure exerted against the outer coats by the contents of the eyeball.
pressure load
mean circulatory filling pressure
a measure of the average (arterial and venous) pressure necessary to cause filling of the circulation with blood; it varies with blood volume and is directly proportional to the rate of venous return and thus to cardiac output.
pressure natriuresis
thought to participate in regulating the volume of extracellular fluid levels when the normal neurohumoral mediators are impaired; the increase in water and sodium ion excretions which occur when blood pressure is elevated because of an increase in the circulating blood volume.
pressure necrosis
necrosis of tissue caused by exclusion of circulation by external compression, e.g. in prolonged recumbency, or due to too-tight bandage, collar, harness.
negative pressure
pressure less than that of the atmosphere.
oncotic pressure
the osmotic pressure of a colloid in solution.
osmotic pressure
the potential pressure of a solution directly related to its solute osmolar concentration; it is the maximum pressure developed by osmosis in a solution separated from another by a semipermeable membrane, i.e. the pressure that will just prevent osmosis between two such solutions.
pressure point granuloma
see pressure points (below).
pressure point pyoderma
see pressure points (below).
pressure points
parts of the body subject to pressure when the animal is recumbent, wearing harness or saddlery, or during restraint. Usually bony prominences such as the point of the hock, hip, shoulder, elbow and lateral aspects of limbs. These are predisposed to callus formation, infection pyoderma and granulomas.
positive pressure
pressure greater than that of the atmosphere.
pulse pressure
difference between systolic and diastolic pressures in arteries.
pressure receptors
e.g. the blood pressure receptors in the aortic arch and the carotid sinus.
pressure sore
decubitus ulcer.
systolic pressure
the highest reading in the arterial blood pressure cycle. A reflection of the ejection pressure of left ventricular systole, and the elasticity of the arterial system.
venous pressure
the blood pressure in the veins. See also central venous pressure.
wedge pressure
intravascular pressure as measured by a swan-ganz catheter introduced into the pulmonary artery; it permits indirect measurement of the mean left atrial pressure.
pressure wrap
bandages which apply pressure to underlying tissues; used after trauma to limit the development of edema, and in the management of lymphedema.

Patient discussion about pressure

Q. how can i reduce my blood pressure?

A. The main steps in lowering high blood pressure is to take some very important changes in lifestyle- consuming much less salt in food, losing weight and exercising regulary. If this doesn't help (and usually it doesn't help mainly when people don't try hard enought and make an effort), medications can be added to control the blood pressure.

Q. what do i need to do to bring down my blood pressure? what cause a high blood pressure? what are the risks? of high blood pressure ? how can i deal with it effectively ?

A. here are two really good sites that show you specifics: http://www.lifeclinic.com/focus/blood/loweringit.asp
http://www.ehow.com/how_12778_eat-lower-blood.html?ref=fuel&utm_source=yahoo&utm_medium=ssp&utm_campaign=yssp_art Hope this helps.

Q. What Are the Complications of High Blood Pressure? My wife suffers from high blood pressure. What are the possible complications that are so dangerous? Why is it important to keep high blood pressure under balance?

A. While elevated blood pressure alone is not an illness, it often requires treatment due to its short and long-term effects on many organs. The risk is increased for: Cerebrovascular accident (CVAs or strokes), myocardial infarction (heart attack), hypertensive cardiomyopathy (heart failure due to chronically high blood pressure),hypertensive retinopathy - damage to the retina, hypertensive nephropathy- chronic renal failure due to chronically high blood pressure and hypertensive encephalopathy- confusion, headache and convulsions due to edema in brain that can lead to death. Therefore, it is considered very important to reduce blood pressure to normal levels with strict medical supervision.

More discussions about pressure
References in periodicals archive ?
50, at an initial effective confining pressure of 100 kPa.
At this high temperature, the impact of confining pressure on compressive strength becomes erratic (Fig.
The role of confining pressure on ballast performance under cyclic loading has been investigated by Indraratna et al.
The enhancement in axial deformation control may be because of more confining pressure uniformly exerted by the CFRP strips.
The influence factors of dynamic strength mainly include relative density, confining pressure, initial shear stress, test method, sampling pattern and lithology etc.
The stress-strain characteristics of saturated samples under different consolidated confining pressure [[sigma].
Comparisons showed that the confining pressure values obtained from the assumption of uniform stress distribution over the surface of concrete core were consistent with the maximum lateral pressure at the corners while effective lateral pressure can be considered as minimum confining stresses on flat sides.
The study is not only observation to liquefaction phenomena but also influence of confining pressure and cyclic deviator stress on liquefaction of clayey sand.
The deformability could also be increased by providing sufficient confining pressure to the concrete core within critical region in the following ways by: (1) confining the concrete member using circular or rectangular hollow steel tube (Ellobody and Young 2006; Kuranovas and Kvedaras 2007; Salna and Marciukaitis 2007; Szmigiera 2007; Soundararajan and Shanmuhasundaram 2008; Kuranovas et al.
t = 8 sec in Figure 1(b)] and eventually reaches a value equal to the initially applied confining pressure.
However, much less is known about the behaviour of concrete in FRP-confined square columns, in which the confining pressure provided by the FRP varies over the cross-section and only part of the concrete is effectively confined (Park, Paulay 1975).