PO.1-Polysaccharide
PO.1
the mouth pressure 100 ms after the start of an occluded
inspiration; a measure of the output of the respiratory center
P5o
the partial pressure of oxygen at which hemoglobin is 50%
saturated with oxygen, standardized to a pH of 7.40; used as a
measure of hemoglobin affinity for oxygen; with a normal value
of 26.6 mm Hg
PAC
abbreviation for premature atrial contraction.
pacemaker,
artificial an electronic device used to stimulate the heart to
beat when the electrical conduction system of the heart
malfunctions, causing bradycardia or ventricular asystole. An
artificial pacemaker consists of an electronic pulse generator,
a battery, and a wire lead that senses the electrical activity
of the heart and delivers electrical impulses to the atria or
ventricles or both when the pacemaker senses an absence of
electrical activity.
pacemaker
cell a myocardial cell with the property of automaticity.
pacemaker
of the heart the SA node or an escape or ectopic
pacemaker in the electrical system of the heart or in the
myocardium. May be sinus nodal, atrial, AV junctional, or
ventricular.
pacemaker
rhythm an arrhythmia produced by an artificial
pacemaker.
pacemaker
site the site of the origin of an electrical impulse.
It can be the SA node or an escape or ectopic pacemaker in any
part of the electrical system of the heart or in the myocardium.
pacemaker
spike the narrow sharp deflection in the ECG caused
by the electrical impulse generated by an artificial pacemaker.
pack years
a specification of an individual's cigarette-smoking history
that is described in the following way: Pack Years = Number of
Packs Smoked per Day X Number of Years Smoked.
Paco2
partial pressure of arterial carbon dioxide.
PAco2
partial pressure of alveolar carbon dioxide.
paired
beats atrial or ventricular ectopic beats occurring
in groups of two. Also called coupled beats, couplet.
paired
PVC's two consecutive PVC's.
PAO2
partial pressure of alveolar oxygen.
Pao2
partial pressure of arterial oxygen.
palate
the bony plate that separates the nasal cavity from the oral
cavity
palliative
alleviating symptoms without curing the underlying cause
pallor
diminished skin color accompanying anemia or in severe
peripheral vasoconstriction accompanying shock.
palmar
pertaining to the palm
palpation
examiner's use of his or her hands to feel for body movement,
lumps, masses, and skin characteristics.
palpitation
a pounding or racing of the heart
pandemic
(of a disease) occurring throughout the population of a country,
a people, or the world
papillitis
an abnormal condition characterized by the inflammation of a
papilla.
papule
a circular area on the skin that is reddened and elevated
paradoxical
occurring at variance with the normal rule.
paradoxical
breathing a pattern of breathing in which the abdomen
is observed to move outward while the lower rib cage moves
inward during an inspiratory effort. This pattern can indicate
excessive respiratory muscle loading, diaphragmatic weakness, or
impending respiratory failure. Also called abdominal paradox
paradoxic
respirations flail chest movement, characterized by
chest wall movement outward on expiration and inward on
inspiration.
paralinguistics factor affecting communication on
either a conscious or unconscious level through the use of
sounds such as giggling, laughing, belittling, ah's and um's,
cracking knuckles, or silence.
paramagnetic susceptibility a characteristic of
oxygen that causes it to be attracted to magnetic fields.
parameter
particular aspect of a variable such as the peak or mean value.
paranasal
situated near or alongside the nose, as the paranasal sinuses
parasympathetic (cholinergic or vagal) activity the
inhibitory action on the heart, blood vessels, and other organs
brought on by the stimulation of the parasympathetic nervous
system. The effect on the heart and blood vessels results in a
decrease in heart rate, cardiac output, and blood pressure and,
sometimes, an AV block.
parasympathetic (cholinergic or vagal) nervous system
part of the autonomic nervous system involved in the control of
involuntary bodily functions, including the control of cardiac
and blood vessel activity. Activation of this system depresses
cardiac activity and produces effects opposite to those of the
sympathetic nervous system. Some effects of parasympathetic
stimulation are slowing of the heart rate, decreased cardiac
output, drop in blood pressure, nausea, vomiting, bronchial
spasm, sweating, faintness, and hypersalivation.
parasympathetic (cholinergic or vagal) tone pertains
to the degree of parasympathetic activity.
parasympatholytic a physiologic response that is the
opposite of one that normally results from stimulation of the
parasympathetic division of the autonomic nervous system.
parasympathomimetic denoting a pharmacologic agent
that mimics the effects of stimulation of organs and structures
by the parasympathetic nervous system by occupying cholinergic
receptor sites and acting as an agonist or by increasing the
release of the neurotransmitter acetylcholine
parenchyma
essential parts of an organ that are concerned with its
function.
parenteral
intravenous, intramuscular, and subcutaneous routes of drug
administration, which all bypass the gastrointestinal system.
parenteral
nutrition administration of nutrients by a route
other than the alimentary canal.
paresis
partial paralysis
paresthesia
abnormal, usually increased, sensations
parietal
layer pertaining to the outer wall of a cavity or organ.
parietal
pleura serous membrane of mesothelial cells and
connective tissue that lines the chest wall, covers the
diaphragm, and extends over the structures of the mediastinum.
parkinsonism group of neurologic disorders
characterized by hypokinesia, tremor, and muscular rigidity.
paroxysm
sudden occurrence; spasm or seizure.
paroxysmal
concerning the sudden, periodic attack or recurrence of symptoms
of a disease.
paroxysmal
nocturnal dyspnea sudden shortness of breath that
occurs several hours after a patient lies down; suggests cardiac
dysfunction.
paroxysmal
supraventricular tachycardia (PSVI) an arrhythmia
with a rate between 160 and 240 beats per minute and usually an
abrupt onset and termination. It originates in the AV junction
as a reentry mechanism involving the AV node alone (AV nodal
reentry tachycardia-AVNRT) or the AV node and an accessory
conduction pathway (AV reentry tachycardia-AVRT). It may occur
with narrow QRS complexes or abnormally wide QRS complexes
because of preexisting bundle branch block or aberrant
ventricular conduction. When abnormal QRS complexes occur only
with the paroxysmal supraventricular tachycardia because of
aberrant ventricular conduction, the tachycardia is called
paroxysmal supraventricular tachycardia (PSVT) with aberrant
ventricular conduction (aberrancy).
paroxysmal
ventricular tachycardia a short burst of ventricular
tachycardia consisting of three or more QRS complexes.
paroxysms
of beats bursts of three or more beats. Three or more
beats are considered to be a tachycardia.
partial
liquid ventilation (PLV) process in which the lungs
are partially filled with perfluorocarbon and a conventional
ventilator provides gas ventilation. The perfluorocarbon is
administered by direct instillation into the endotracheal tube.
partial
pressure the absolute pressure exerted by one gas in
a mixture of gases.
partial-rebreathing
mask simple oxygen mask with the addition of a 300 to
600 mL reservoir bag. The oxygen supply tube is positioned
between the mask and the reservoir bag, and the oxygen flow is
set at a rate sufficient to keep the bag at least partially
inflated throughout inspiration.
partial
thromboplastin time (PTT) a test for detecting
coagulation defects of the intrinsic clotting system by adding
activated partial thromboplastin to a sample of test plasma and
comparing it with a control of normal plasma; normal is 60 to 80
seconds
partial
ventilatory support modes of ventilatory support in
which the patient must contribute to the total minute volume
with spontaneous breathing
particle
filters devices whose purpose is to remove
particulate mater from an area or gas stream.
particle
inertia the tendency of a particle to maintain a
direction and speed of motion unless acted on by another force.
Pascal
under the SI system, the primary unit of pressure, that is, one
Newton/meter2; for ease of calculation, the kilopascal (kPa) is
commonly used, so that one standard atmosphere (at sea level) is
approximately 101 kPa.
Pascal's
law observation that pressure is transmitted without
reduction throughout any enclosed static fluid.
passive
atelectasis collapse of distal lung units due to
persistent ventilation with small tidal volumes
passive
expiration expiration in which the respiratory system
is responding to a sudden release of inspiratory pressure that
requires no muscular effort.
passive
humidification system of humidification that uses
exhaled heat and moisture to humidify the inspired gas; a heat
and moisture exchanger (HME) is a passive humidifier.
passover
humidifier humidifying device that directs gas over
the surface of a body of water; example includes the passover
wick humidifier.
pasteurization the process of applying heat, usually
to milk or cheese, for a specified period for the purpose of
killing or retarding the development of pathogenic bacteria
patch test
a screening test in which a small piece of material containing
the allergy-causing substance is placed on the skin; redness or
edema indicates a positive reaction
patent
open and unblocked, as a patent airway pathological indicative
of or caused by a disease
pathogen
any agent causing disease, especially a microorganism.
pathogenesis the development of disease; pathologic
mechanisms
pathologic
apnea category or type of cessation of air flow that
disrupts breathing for at least 20 seconds, accompanied by
bradycardia with heart rate reduction of 20% below baseline or
oxygen saturation below 80%.
pathologist
one who specializes in the study of disease
pathophysiology the study of the biological and
physical manifestations of disease as they correlate with the
underlying abnormalities and physiological disturbances
Patient
Bill of Rights professional code established by the
American Hospital Association to outline the rights and
responsibilities patients have regarding their medical care,
including their right to refuse treatment to the extent
permitted by law and to be informed of the medical consequences
of their actions.
patient-controlled analgesia (PCA) popular method of
pain control in which the patient can self-administer portions
of a preset amount of intravascular pain medication; the
computerized device administers portions and includes a lockout
interval to automatically inactivate the system if a patient
tries to increase the amount of drug used within a predetermined
time period.
patient
disconnect alarm a system warning that the patient is
not connected to the ventilator, a low patient-pressure alarm.
patient-focused care a nontraditional organization of
services that emphasizes a team approach to service delivery
using cross-trained providers, as well as simplification of
processes required to provide patient care
patient-physician privilege the right of patients to
refuse to divulge or have divulged by their physician, the
communications made between them and their physician
patient-ventilator dyssynchrony a condition in which
the patient is not breathing in synchrony with the ventilator.
PAV
abbreviation for proportional assist ventilation, a mode of
ventilatory support in which the level of mechanical assistance
varies with patient demand
PAWP
abbreviation for pulmonary arterial wedge pressure (also called
the pulmonary capillary wedge pressure [PCWPJ or occluded
pulmonary artery pressure [PAo]); reflects downstream pressure
in the pulmonary circulation; under optimum conditions PAWP
indicates left ventricular end-diastolic pressure (LVEDP), or
left ventricular preload
P axis
the mean of all the vectors generated during the depolarization
of the atria.
PEA
see Pulseless electrical activity.
PCI
see Percutaneous coronary interventions (PCI).
PCIRV
abbreviation for pressure controlled inverse ratio ventilation;
equivalent to time-triggered, pressurelimited, time-cycled
ventilation with I:E ratios greater than 1:1
PCP
abbreviation for Pneumocystis carinii pneumonia; caused by
Pneumocystis carinii (probably a fungi), PCP causes an acute
interstitial pneumonia with high mortality (50%); PCP is most
common among patients with an abnormal or altered immunologic
status, particularly those suffering from AIDS; current
treatment is with co-trimoxazole or pentamidine isethionate
PCV
abbreviation for pressure control ventilation
PCWP
abbreviation for pulmonary capillary wedge pressure; see PAWP
PDA
abbreviation for patent ductus arteriosus, a common
cardiovascular anomaly of infants in which the ductus arteriosus
either fails to close or reopens after birth
peak
expiratory flow rate (PEFR) the maximum, greatest
expiratory flow rate in L/sec
peak flow
a measurement of the maximum amount of gas that can be
forcefully exhaled after a maximum inspiration. Expressed in
L/min.
peak flow
control a device that regulates the maximum flow a
ventilator delivers.
peak flow
meter monitoring device for the management of asthma.
peak of the
T wave coincident with the vulnerable period of
ventricular repolarization, during which a premature ventricular
contraction (PVC) can initiate ventricular tachycardia or
ventricular fibrillation.
pectoralis
major the large fan-shaped muscle that arises from
the sternum and clavicle and inserts into the upper arm;
accessory muscle of ventilation
pectoriloquy the transmission of the sounds of speech
through the chest wall
pectus
carinatum condition in which the chest bows out at
the sternum similar to that of a pigeon.
pectus
excavatum condition in which the sternum is depressed
and deviated somewhat like a funnel.
PEEP
abbreviation for positive end-expiratory pressure; the
application and maintenance of pressure above atmospheric at the
airway throughout the expiratory phase of positive pressure
mechanical ventilation
PEEP-exhalation valve an exhalation valve fitted with
a PEEP device.
PEEP/CPAP
pressure control valve a mechanism that regulates the
pressure limits of the PEEP/CPAP devices in a ventilator system.
PEEP/IMV
selector valve a control that can be set to determine
if the ventilator acts in IMV or PEEP modes or both.
pelvic
inflammatory disease (PID) inflammation of the female
pelvic organs, usually caused by bacteria
pendelluft
movement of gas from 'fast' to 'slow' filling spaces during
breathing; alternatively, the ineffective movement of gas back
and forth (accompanied by mediastinal shifting) between a
healthy lung and one with a flail segment caused by a crushing
chest injury
pendeluft
ventilation result of gas mixing between lung regions
that have different time constants; also called outof-phase
ventilation; motion of gas between two neighboring units during
phasic ventilation.
penicillinase resistant a descriptive term applied to
certain antibiotics resistant to the action of penicillinase, an
enzyme produced by some bacteria that activates penicillin
penetrating
trauma chest trauma that results from knife and gun
shot wounds and whose mechanism of injury depends on the
velocity and size of the penetrating object.
peptide
compound created when amino acids are linked together, the OH
from the carboxyl group of one amino acid and the H from the
amine group of another amino acid splitting off.
peptide
bond bond between the amino acids is called a peptide
bond.
percent
body humidity (%BH) referring to the amount of water
vapor in a volume of gas as the percent of the water in gas
saturated at a body temperature of 37° C (43.8 mg/L)
percent
cycle time ratio of inspiratory time to total cycle
time expressed as a percentage.
percent
pause time a setting on the Siemens Servo ventilators
that, in conjunction with the "I" time, sets respiratory rate.
percent
solution concentration measure of a solute usually
expressed with units of mass or volume in ratios such as
weight/weight, weight/volume, and volume/volume; commonly used
in clinical situations.
percussion
examination technique in which the examiner places a
finger firmly against a body part and then strikes that finger
with a fingertip from the other hand, producing sounds that may
suggest normal or abnormal tissue.
percussion
therapy technique of rapidly clapping, cupping, or
striking the external thorax directly over the lung segment
being drained, with either cupped hands or a mechanical device.
percutaneous through the skin
percutaneous coronary interventions (PCI)
catheterbased techniques to enlarge the lumen of the occluded
section of the affected coronary artery mechanically by means of
one or more of the following:
· Percutaneous transluminal
coronary angioplasty (PTCA)
· Coronary artery stenting
· Directional coronary
atherectomy (DCA)
· Rotational atherectomy
percutaneous transluminal coronary angioplasty (PTCA)
inserting a balloon-tipped catheter into the occluded or
narrowed coronary artery and then inflating the balloon, thus
fracturing the atheromatous plaque and dilating the arterial
lumen. This procedure, also referred to as balloon angioplasty,
is the most commonly performed invasive treatment for coronary
artery occlusion. It is often followed by insertion of a
coronary artery stent.
perfuse
the passage of fluid (usually blood) through the body
perfusion
passing of blood or fluid through a vascular bed.
peribronchial located around the bronchi.
pericardial
effusion fluid within the pericardial cavity or sac.
pericardial
tamponade accumulation of fluid under pressure within
the pericardial cavity.
pericardiocentesis procedure that is commonly used in
the treatment of cardiac tamponade and involves removing blood
from the pericardial sac by placing a needle into the
pericardium and withdrawing the accumulated blood.
pericarditis inflammation of the pericardium
accompanied by chest pain somewhat resembling that of acute
myocardial infarction. The ECG in acute pericarditis mimics that
of acute myocardial infarction because of marked ST segment
elevation.
pericardium
the tough fibrous sac containing the heart and origins of the
superior vena cava, inferior vena cava, aorta, and pulmonary
artery. The pericardium consists of an inner, two-layered,
fluid-secreting membrane (serous pericardium) and an outer,
tough, fibrous sac (fibrous pericardium). The inner layer of the
serous pericardium, the visceral pericardium, or as it is more
commonly known, the epicardium, covers the heart itself; the
outer layer, the parietal pericardium, lines the fibrous
pericardium. Between the two layers of the serous pericardium is
the pericardial space or cavity (or sac), which contains the
pericardial fluid.
perinatal
of or pertaining to the time and process of giving birth or to
being born
perioperative of or pertaining to the period of time
immediately before, during, and after surgery
periosteum
the fibrous covering of long bones
peripheral
airways small bronchioles on the outer sections of
the lung.
peripheral
vascular resistance the resistance to blood flow in
the systemic circulation that depends on the degree of
constriction or dilation of the small arteries, arterioles,
venules, and small veins making up the peripheral vascular
system.
peripheral
vasoconstriction constriction of blood vessels,
especially the small arteries, arterioles, venules, and small
veins, causing an increase in blood pressure and a decrease in
the circulation of blood beyond the point of vasoconstriction.
peripheral
vasodilatation dilation of blood vessels, especially
the small arteries, arterioles, venules, and small veins,
causing a decrease in blood pressure.
periodic
breathing regular respiration of up to 20 seconds
followed by apnea periods of no more than 10 seconds occurring
three times or more in succession; may be a normal event for
some patients.
periodic
leg movements of sleep condition characterized by
pathologic repetitive myoclonic contractions, which can result
in frequent arousals or awakenings and can cause daytime
symptoms such as excessive daytime sleepiness.
peristalsis
a progressive wave movement that occurs involuntarily in hollow
tubes of the body, especially the intestines.
peritoneal
dialysis a dialysis procedure in which the peritoneum
is used as the diffusible membrane, with a dialysate fluid
infused and removed directly into the peritoneal cavity
peritonitis
inflammation of the membrane that lines the abdominal cavity and
covers the viscera
peritubular
around the tubules; specifically around the proximal or distal
tubules of the nephron
perivascular located around a vessel, especially a
blood vessel.
permanent
gas the gaseous phase of a substance with a critical
temperature so low that it cannot be compressed into a liquid
under ambient conditions
permeable
capable of allowing the passage of fluids or substances in
solution.
permissive
hypercapnia during ventilatory support, the use of
subnormal volumes to protect the lung against barotrauma; the
Paco2 is allowed to rise as long as the pH remains in a safe
range
perpendicular of a lead axis (perpendicular axis) a
line intersecting or connecting with the lead axis at ± 90 0 (or
a right angle), at its electrically "zero" point. Also referred
to simply as the perpendicular.
PERRLA
acronym indicating pupils equal, round, react to light,
accommodation; a normal physical examination finding
persistent
pulmonary hypertension of the newborn (PPHN) a
clinical syndrome seen in infants soon after birth and
characterized by abnormally increased pulmonary vascular
resistance
persistent
pulmonary hypertension of the neonate (PPHN) an
elevated pulmonary vascular resistance in the newborn caused by
a low P02 level. The infant's ductus arteriosus remains open as
a result of this condition.
pertussis
an acute, highly contagious respiratory disease characterized by
paroxysmal coughing that ends in a loud whooping inspiration
petechia (petechiae)
a tiny spider-like hemorrhage under the skin
P/F ratio
a ratio of the arterial partial pressure of oxygen to
the inspired fractional concentration of oxygen (Pao2/FI02); a
measure of the efficiency of oxygen transfer across the lung
pH
expression of the concentration or strength of an acid or base;
indicates the hydrogen ion concentration [H+] in a solution;
mathematically defined as the negative logarithm of the hydrogen
ion concentration.
PH2O
the partial pressure of water vapor at body temperature and 100%
saturation (BTPS), 47 mm Hg.
phagocyte,
phagocytic, phagocytosis the process by which cells
surround and digest certain particles (e.g., bacteria, protozoa,
and debris)
phalanges
the bones of the fingers and toes.
pharmacodynamics drug's action in the body, both at a
molecular level and in terms of overall clinical effect.
pharmacokinetics drug's movement in the body through
the processes of absorption, distribution, and elimination.
pharmacology science describing the chemical entities
of drugs and their interactions with the body, focusing in
particular on these five aspects of each drug: (1) its chemical
and physical properties, (2) the movement of drug into, through,
and out of the body (pharmacokinetics), (3) the effect of the
drug on the body (pharmacodynamics), (4) drug indications and
dosages, and (5) side effects and toxicity.
pharyngitis
inflammation or infection of the pharynx, usually causing
symptoms of a sore throat
phases of acute MI
phases of
depolarization and repolarization see Cardiac action
potential.
phases of
thrombolysis (1) Release of tPA from the endothelium
of the blood vessel wall into the plasma; (2) plasmin formation
by conversion of plasminogen attached to the fibrin strands
within the thrombus through the action of tPA; (3) fibrinolysis
by the breakdown of fibrin through the action of plasmin,
causing the platelets to separate from each other and the
thrombus to break apart.
phase
variable one of four factors measured and used to
start, sustain, and end any phase of the respiration cycle:
pressure, volume, flow, and time.
phlebotomy
surgical puncture of a vein to withdraw blood
phlegm
mucus from the tracheobronchial tree
phonocardiography the analog recording of heart
sounds, usually on a strip chart recorder; useful in the
diagnosis of certain valvular abnormalities that produce heart
murmurs
phosphate
a compound of phosphoric acid.
phospholipid lipid similar to triglyceride except
that instead of three fatty acids attached to a glycerol, one of
the fatty acid chains is replaced by a chemical structure
containing phosphorus and nitrogen; its "head" is composed of
the phosphorus and nitrogen group, and its two "tails" are
composed of the two fatty acids so that the head attracts water
(hydrophilic) while the tails repel it (hydrophobic), allowing
it to bridge or join two different chemical environments; a
primary component of cell membranes and of pulmonary surfactant.
photophobia
abnormal sensitivity to light, especially by the eyes.
photoplethysmography noninvasive technology to
measure blood pressure that uses a small finger cuff and a
technique similar to pulse oximetry: a light source and detector
built into the cuff measure the absorption of a specific
wavelength of light passed across the arterial bed of the
finger; as the cuff inflates, it eliminates the pulsatile
component of absorption, and cuff pressure equals intraarterial
pressure.
phototherapy treatment of disease by exposure to
light
phrenic
nerves paired nerves that originate as branches of
spinal nerves C3-C5, pass down along the mediastinum, and
innervate the diaphragm
physical
analyzer a gas analyzer that employs the principles
of physics (heat, electrical flow, etc.) to measure gas
concentration.
physiological AV block an AV block that occurs only
when a rapid atrial arrhythmia, such as atrial fibrillation,
atrial flutter, and atrial tachycardia, is present.
PIC
abbreviation for premature junctional contraction.
Pickwickian
syndrome an abnormal condition characterized by
severe obesity, decreased responsiveness to carbon dioxide, a
restrictive pulmonary function pattern, hypersomnolence, and
polycythemia
PIE
abbreviation for pulmonary interstitial emphysema; a form of
pulmonary barotrauma due to air leakage into lung tissue
piezoelectric crystal a transducer capable of
converting electrical energy in the physical energy of high
frequency vibrations
piezoelectric plethysmography type of plethysmography
apparatus that replaces the wire coils from the elastic belts
with a piezoelectric buckle, which encloses a sensor to generate
a voltage in response to stretch passed through the ends of the
belts.
piezoelectric transducer a transducer capable of
converting electrical energy in the physical energy of high
frequency vibrations
Pimax
abbreviation for maximum inspiratory pressure, or the negative
pressure generated during a maximally forced inspiratory effort
against an obstruction to flow; also called maximum inspiratory
force (MIF) and negative inspiratory force (NIF)
Pin Index
Safety System one of three indexing safety systems
for medical gases. This system uses a specific combination of
two holes in the post valve just below the gas outlet for each
gas or gas mixture; any regulator or devise intended to connect
to the valve will have pins that correspond to the holes,
allowing a proper connection.
pinna
the soft-tissue, outer shell of the ear that projects from the
side of the head.
PISS
abbreviation for pin-indexed safety system
piston bag
a reservoir that contains a volume of gas to be delivered to the
patient when it is compressed by a piston.
piston
compressor a gas source in which a volume of gas is
reduced in volume and pressurized by a piston.
pituitary
gland a small, gray, rounded body attached to the
base of the brain.
pK
the negative log of the ionization constant of a solution; the
buffering power of a buffer system is greatest when its pH and
pK values are equal; pKa is the negative log of the acid
component of a buffer
placenta
the highly vascular organ through which the fetus absorbs oxygen
and vital nutrients, and excrete carbon dioxide and other waste
products of metabolism
placenta
abruptio (also abruptio placentae) separation of a
normally implanted placenta in a pregnancy of 20 weeks or more
duration or during labor but before delivery; a significant
cause of maternal and fetal mortality
placenta
previa an abnormal condition of pregnancy in which
the placenta is implanted low in the uterus, such that it
impinges or covers the internal os of the cervix
plaintiff
a person who brings an action; a person who seeks remedial
relief for an injury to his rights
planimeter
an instrument designed for measuring the area of surfaces.
plaque
a deposit of hardened material lining the blood vessel; or a
gummy accumulation of microorganisms that clings to teeth and is
considered the forerunner of caries and periodontal disease
plasma
the watery straw-colored fluid part of the lymph and the blood
in which the leukocytes, erythrocytes, and platelets are
suspended. Plasma is made up of water, electrolytes, proteins,
glucose, fats, bilirubin, and gases and is essential for
carrying the cellular elements of the blood through the
circulation, transporting nutrients, maintaining the acid-base
balance of the body, and transporting wastes from the tissues.
Plasma and interstitial fluid correspond closely in content and
concentration of proteins; therefore, plasma is important in
maintaining the osmotic pressure and the exchange of fluids and
electrolytes between the capillaries and the tissues.
plasmapheresis the process of separating blood into
its components by centrifuging
plasmin
an enzyme that dissolves fibrin within the thrombus, helping to
break the thrombus apart (thrombolysis). See Plasminogen.
plasminogen
a plasma glycoprotein that converts to an enzyme, plasmin, when
activated by tissue-type plasminogen activator (tPA)Plasmin, in
turn, dissolves the fibrin strands (fibrinolysis) binding the
platelets together within a thrombus, initiating thrombolysis.
plateau
pressure end-inspiratory peak alveolar pressure
attained during mechanical ventilation and which should,
ideally, be kept below 30 cm H20, in conjunction with overall
lung protective ventilation strategy.
platelet
activation the second phase of thrombus formation
that occurs after the platelets become bound to the collagen
fibers. The platelets become activated and change their shape
from smooth ovals to tiny spheres while releasing adenosine
diphosphate (ADP), serotonin, and thromboxane A2 (TxA2) ,
substances that stimulate platelet aggregation. Platelet
activation is also stimulated by the lipid-rich gruel within the
atherosclerotic plaque. At the same time, the GP IIb/IIIa
receptor is turned on to bind with fibrinogen. While this is
going on, tissue factor is being released from the tissue and
platelets.
platelet
aggregation the third phase of thrombus formation.
Once activated, the platelets bind to each other by means of
fibrinogen, which binds to the platelets' GP IIb/IIIa receptors.
Stimulated by ADP and TxA2, the binding of fibrinogen to the GP
IIb/IIIa receptors is greatly enhanced, resulting in a rapid
growth of the platelet plug. By this time, the prothrombin has
been converted to thrombin by the tissue factor.
platelet GP
IIb/IIIa receptor inhibitor a compound that blocks
the GP IIb/IIIa receptors on activated platelets from binding to
fibrinogen, thus inhibiting platelet adhesion and aggregation
and further thrombus formation. CP IIb/IIIa receptor inhibitors
include abciximab and eptifibatide.
platelet
adhesion the first phase of thrombus formation. After
the denudation or rupture of an atherosclerotic plaque, the
platelets are exposed to collagen fibers and von Willebrand
factor (vWF). The platelets' receptors GP la binds with the
collagen fibers and GP Ib and GP IIb/IIIa with vWF, which in
turn also binds with collagen fibers. The result is the adhesion
of platelets to the collagen fibers within the plaque, forming a
layer of platelets overlying the damaged plaque.
platelets
small cells present in the blood that are necessary for
coagulation of blood and maintenance of hemostasis. Contain
adhesive glycoproteins (GP) receptors that bind with various
components of connective tissue and blood to form thrombi. The
major receptors are GP Ia, GP Ib, and GP IIb/IIIa. Platelets
also contain several substances that when released upon platelet
activation promote thrombus formation by stimulating platelet
aggregation. These include adenosine diphosphate (ADP),
serotonin, and thromboxane A2 (TxA2).
platypnea
the opposite of orthopnea; that is, an abnormal condition
characterized by difficult breathing in the standing position,
which is relieved in the lying or recumbent position
plethora
fullness of blood vessels at the skin surface, often occurring
with vasodilation or hypercapnia.
plethysmograph a device for measuring pressure; in
pulmonary physiology, a chamber in which the subject sits in
order to measure lung pressures and volumes
plethysmography the process of measuring and
recording variations in the volume of an organ or body part with
a plethysmograph
pleura
serous membrane enclosing the lung and composed of a single
layer of flat mesothelial cells on a delicate membrane of
connective tissue.
pleural
effusion the abnormal collection of fluid in the
pleural space
pleural
empyema a pleural effusion in which the fluid is
purulent or contains pyogenic organisms
pleural
friction rub continuous grating sound heard in
auscultation of the lungs; resembles two pieces of leather or
two hands being rubbed together; occurring when pleurae are
inflamed or when fluid accumulates in the pleural cavity.
pleural
space space between the visceral and parietal layers
of the pleurae.
pleurisy
pain that comes from the pleural surface usually a direct result
of viral infections but has been generalized to any condition
(for example, pulmonary embolism) causing pleural pain.
Synonymous with pleurodynia
pleurodesis
the procedure of fusing the parietal and visceral pleura to
prevent formation of pleural fluid or recurrence of pneumothorax
PMI
abbreviation for point of maximum impulse
P mitrale
a wide notched P wave occurring in the presence of left atrial
dilatation and hypertrophy. Typically associated with severe
mitral stenosis.
PND
abbreviation for paroxysmal nocturnal dyspnea
pneumatic
nebulizer a device that produces an aerosol cloud
using a pressurized gas source as the propellant.
pneumatic
drive mechanism a method of operating a ventilator
using pressurized gas as a power source.
pneumatic
expiratory timing device a gas-powered device that
controls expiratory time; an example would be to use a
controlled leak to deflate a diaphragm and open an inspiratory
valve.
pneumobelt
unconventional ventilation that consists of an inflatable rubber
bladder held over the abdomen by an adjustable corset and
assists diaphragmatic motion by causing piston-like motions of
the abdominal viscera.
pneumogram
12- to 24-Hour recording of heart rate, respiratory impedance,
oxygen saturation, nasal-oral airflow, and esophageal pH.
pneumatocele a thin-walled, air-filled cyst occurring
in lung tissue
pneumocardiography the recording of variations in
cardiac function through sensors that monitor respiratory
changes, such as pressure changes in the bronchi or changes in
thoracic dimensions
pneumocephalus a condition in which gas or air is
inside the cranium
pneumography recording of respiratory movements on a
graph
pneumoconiosis any disease of the lung caused by
chronic inhalation of inorganic dusts, usually mineral dusts of
occupational or environmental origin
pneumocyte
(also pneumonocyte) a general term applied to the
cells constituting the alveolar region of the lungs
pneumomediastinum a presence of air or gas in the
mediastinal tissues, which may lead to pneumothorax or
pneumopericardium
pneumonectomy
the surgical removal or all or part of a lung
pneumonia
an inflammatory process of the lung parenchyma, usually
infectious in origin pneumonitis inflammation of the lung
pneumopericardium a presence of air or gas in the
pericardium
pneumoperitoneum a presence of air or gas in the
peritoneal cavity; may occur as the result of disease, or may be
induced for diagnostic visualization
pneumotachometer an instrument for measuring the
velocity of respired air.
pneumotachygraph an instrument that incorporates a
pneumotachometer to recording variations in the flow of
respiratory gases
pneumotaxic
center a portion of the pontine respiratory centers
that influence the respiratory components of the medulla. Neural
impulses from the pneumotaxic center simultaneously cause (1)
the depth of breathing to decrease and (2) the rate of breathing
to increase by almost an equal amount. Some investigators
believe the pneumtaxic center is closely related to the
so-called panting center in animals such as dogs.
pneumothorax air in the pleural space that can cause
collapse of the lung and shortness of breath; may result
following blunt chest injury resulting from direct puncture of
the lung by a fractured rib, with deceleration injuries causing
a tear in the lung tissue, or as a result of a crush injury
rupturing alveoli.
PO2
one of three primary measurements made in arterial blood gas
analysis, significant in assessing oxygenation.
point-of-care (POC) testing analysis at the bedside,
as opposed to conventional laboratory testing
point of
maximal intensity (PMI) the place where the apical
pulse is palpated as strongest, often in the fifth intercostal
space of the thorax, just medial to the left midclavicular line.
point of
service type of health insurance plan that is a
hybrid of the HMO and PPO plans. Point-of-service plans attempt
to provide the tight utilization controls of the HMO coupled
with the ability to choose a nonparticipating provider at the
point (time) of receiving the service, thus the name "point of
service."
Poiseuille's law the law relating pressure difference
needed for laminar flow through a tube to the viscosity of the
fluid, the length of the tube, the rate of flow, and the tube
radius
polar
type of molecule that forms as the result of unequal charge
distribution on a molecule, rather than the sharing or transfer
of electrons.
polarity
the condition of being positive or negative. Polarized (or
resting) state of the cell The condition of the cell after
repolarization, when the interior of the cell is negative and
the outside is positive.
polarographic electrode a type of sensor used in gas
analysis in which electrodes having opposite magnetic charges
are used to determine the amount of a paramagnetic gas in a
mixture of gases.
poliomyelitis acute viral disease now rare in the
United States, characterized by fever, sore throat, headache,
and vomiting, with stiffness of neck and back; possibly
progressing to involvement of the CNS, pleocytosis in the spinal
fluid, and perhaps paralysis.
polycythemia an increase in the number of
erythrocytes in the blood caused by chronic hypoxemia secondary
to pulmonary disease, heart disease, or prolonged exposure to
high altitudes, or it may be idiopathic.
polymerase
chain reaction (PCR) see also antigen detection.
Newer technique applied to sputum samples to help in the rapid
identification of pathogens that may be difficult to culture or
pathogens scarcely growing because of prior antibiotic
treatment; application of PCR to BAL fluid increases the
sensitivity and is rapid in detecting CMV, PCP, and
mycobacterial pulmonary infection.
polymorphonuclear having a nucleus with a number of
lobules or segments connected by a fine thread
polyp
a small, tumor-like growth that projects from the surface of a
mucous membrane
polysaccharide type of carbohydrate that is a complex
sugar.
