O2ER-Outlet Valve

02ER abbreviation for oxygen extraction ratio; the ratio of oxygen consumption to oxygen delivery

O2 pulse the ratio of oxygen consumption to heart rate (mL oxygen consumed per beat); a measure of the heart's efficiency in delivering oxygen

obesity hypoventilation syndrome a general syndrome involving chronic hypercapnia and hypoxemia, sleep apnea, and decreased respiratory center responsiveness to carbon dioxide. Complications, due primarily to chronic hypoxemia, include polycythemia, pulmonary hypertension, and cor pulmonale

oblique slanting; not perfectly vertical or horizontal obliterate to remove or destroy

obstetrics the branch of medicine concerned with pregnancy and childbirth

obstructive sleep apnea (OSA) a condition in which five or more apneic periods (of at least 10 seconds each) occur per hour of sleep and characterized by occlusion of the oropharyngeal airway with continued efforts to breathe

obtunded insensitive to pain or other stimuli due to a reduced level of consciousness

obturator a device used to block a passage or a canal or to fill in a space, as the obturator used to insert a tracheostomy tube

occipital referring to the back part or bone of the head.

occlude to close, obstruct, or join together.  

ocular of or pertaining to the eye; also an eyepiece in any instrument

Ohm's law principle describing properties of electric systems, assuming linear relations between a pressure, resistance, and flow term, without loss of thermal energy, or turbulence, thus allowing application of easily measured quantities, such as electric resistance, to other circular systems of single or connected circuits in which measurement may be more technically difficult; the most general expression of this law describes the relation of voltage, resistance, and impedance.

olfactory pertaining to the sense of smell.

oliguria a diminished capacity to form and pass urine; for adults, generally defined as < 500 ml/day

oncogene a gene in a virus that can prompt a cell to turn malignant

oncotic marked by or associated with swelling; often used as a synonym for osmotic forces

oncotic pressure osmotic pressure of a colloid in solution, such as exists in a higher concentration of protein in the plasma on one side of a cell membrane than in the neighboring interstitial fluid.

Ondine's curse apnea caused by loss of automatic control of respiration (derived from the name of a fabled water nymph)

opacification the process of becoming opaque (less able to transmit light or penetrating radiation); used commonly to refer to the development of areas of increased density on the x-ray, as occurs in ARDS

opacity the state of being opaque or not transparent

open-circuit spirometry method of spirometry in which the subject takes a full inspiration before placing the mouthpiece into his or her mouth to perform a test.

open-loop control means of mechanical system control in which change in the input causes a change in the output but without flow of information from the output to generate a new input to "close the loop."

open-top tent an environmental control enclosure used for small children and featuring a open top to facilitate CO2 washout.

open reduction exposure of a fractured or dislocated bone through a surgical incision to realign the bone ends

ophthalmoscopy, ophthalmoscopic an examination of the interior of the eye

opiate natural or synthetic derivative of morphine, derived from the opium poppy, stimulating mu (µ), delta, and kappa (K) opiate receptors in the brain and spinal cord to decrease the sensation of pain; also acts as a potent sedative or cough suppressant.

opportunistic referring to an infection caused by normally nonpathogenic organisms in a host whose resistance has been decreased by disorders such as diabetes mellitus, human immunodeficiency virus (HIV), or cancer; a surgical procedure; or immunosuppressive drugs

opposite (or reciprocal) ECG leads see "Reciprocal" ECG changes.

optimal sequential pacemaker (DDD) an artificial pacemaker that paces the atria or ventricles or both when spontaneous atrial or ventricular activity is absent.

optimum PEEP the ideal level of PEEP, balancing benefits and risks

optode intra-arterial sensor placed through an arterial cannula and into an artery.

oral anticoagulant see Warfarin sodium.

oral appliance dental device for clinical use; can be characterized primarily as either a tongue retaining device (TRD) or mandibular advancing device (MAD).

organelle membrane-bound, organized living substances present within nearly all cells. Organelles participate in a variety of different cellular functions.

orifice an entrance or outlet to a body cavity or tube

orificial resistance flow resistance caused by changing diameters of gas-flow orifices.

oropharyngeal airway airway device with a relatively rigid structure designed to be inserted into the mouth between the lips and teeth and extend from the lips to the pharynx, following the natural curvature of the tongue, without entering the larynx or esophagus.

oropharynx one of three components of the throat or pharynx, extending behind the mouth from the soft palate to the hyoid bone; contains the palatine and lingual tonsils.

orotracheal of or pertaining to the passageway from the mouth to the trachea; usually applied to tubes or catheters placed in the trachea through the mouth, such as an orotracheal tube or orotracheal suctioning

orthopnea labored breathing in the reclining position orthostatic pertaining to or caused by standing upright, as with orthostatic hypotension

OSA abbreviation for obstructive sleep apnea; a condition in which five or more apneic periods (of at least 10 seconds each) occur per hour of sleep and characterized by occlusion of the oropharyngeal airway with continued efforts to breathe

Osborn wave the distinctive narrow, positive wave that occurs at the junction of the QRS complex and the ST segment-the QRS-ST junction-in hypothermic patients with a core body temperature of >=95F. Also referred to as the "J wave," the "J deflection," or the "camel's hump." Associated ECG changes include prolonged PR and QT intervals and widening of the QRS complex.

oscillation a back-and-forth motion; vibration or the effects of mechanical or electrical vibration

OSHA abbreviation for the Occupational Safety and Health Administration, a branch of the U.S. Department of Labor responsible for regulation pertaining to on-the-­job safety

osmolarity the osmotic pressure of a solution expressed in osmols or milliosmols per kilogram of the solution

osmosis process of transferring water molecules through a semipermeable membrane; involves the movement of water from an area of high concentration of water to an area of low concentration in an attempt to make the concentrations equal.

osmotic pressure externally applied hydrostatic pressure that stops the flow of a solvent through a membrane.

osteophyte a bony outgrowth, usually branch shaped

osteoporosis decrease in the amount of bone mass, which can lead to fractures after minimal trauma.

osteoradionecrosis radiation tissue damage.

ostomy a surgical opening of the bowel to the outside of the body

otitis inflammation or infection of the ear, such as otitis media or otitis externa

otitis media middle ear infection

otoscopy visual examination of the ear using an otoscope

outflow resistance the force against which the ventricles must pump to move blood into the arteries

outflow valve a control device that regulates the gas exiting a system.

outlet valve a safety valve on a piped-gas system that prevents the high-pressure gas from free flowing.

Overdistension-O2 Relay

overdistention a state of stretch or expansion beyond the normal limits

overdrive suppression the suppression of spontaneous depolarization of the SA node or an escape or ectopic pacemaker by a series of electrical impulses (from whatever source) that depolarize the pacemaker cells prematurely. Following termination of the electrical impulses, there may be a slight delay in the appearance of the next expected spontaneous depolarization of the affected pacemaker cells because of a depressing effect that premature depolarization has on their automaticity.

overhydration a state characterized by an excess of body fluids

over pressure alarm a warning that the pressures in a system have exceeded predetermined levels.

over pressure relief a device that allows pressure to be released from a system that has exceeded desired pressure limits.

overload refers to increased pressure, volume, or both within a chamber of the heart from various causes, resulting in chamber enlargement from dilatation, hypertrophy, or both. Examples are right atrial enlargement, left atrial enlargement, right ventricular hypertrophy, and left ventricular hypertrophy.

oxidative phosphorylation joining of a phosphate group to adenosine diphosphate (ADP) to form ATP during catabolism.

oximeter spectrophotometer using specific wavelengths in the oxyhemoglobin spectrum to measure hemoglobin oxygen saturation in the blood.

oximetry the process of determining the saturation of hemoglobin with oxygen with an oximeter oxygen-conserving devices special low-flow delivery systems modified to reduce the oxygen waste that occurs during patient exhalation

oxygen adder a device or system that adds oxygen to a flow of gas to regulate the oxygen concentration.  

oxygen analyzer device used to measure the concentration of oxygen administered to patients.

oxygen blender a device that mixes oxygen with air or other gases to provide precise oxygen concentrations.

oxygen cannula most widely used device for administering low-flow oxygen to infants, children, and adults in the hospital and in the home; consists of a delivery tube that ends in two short prongs, each about one-half inch in length, made of soft, pliable plastic.

oxygen catheter standard low-flow oxygen delivery system of choice until the late 1960s (rarely used today); consists of a soft, pliable plastic tube about 12 inches in length with a series of small holes at the distal end and a fitting at the other end to connect it to the oxygen supply tubing.

oxygen concentrator device designed to produce a low flow (0.5 to 5.0 L/min) of high-purity oxygen (90% to 95%) from room air by either molecular adsorption of nitrogen or filtration of air through a membrane; the most widely used source of oxygen in the home and extended care facilities.

oxygen conserver device that supplies a flow of oxygen only when it is needed, on demand at the initiation of inspiration. The conserver is placed between the oxygen supply and the delivery device, which can be a nasal catheter, nasal cannula, or transtracheal catheter.

oxygen consumption (VO2) rate of O2 uptake by the body, measured by analyzing inspired and expired O2 in a ventilator circuit (approximately 220 to 250 mL/min in the adult under resting conditions); equal to cardiac output multiplied by the arterial-venous content difference.

oxygen content the total volume of oxygen contained within a given volume of blood. It includes both the oxygen dissolved in the plasma and the oxygen that is attached to hemoglobin in the red blood cells. (Units = vol% or ml O2/100 ml blood.)

oxygen control a device in a ventilator that regulates the oxygen concentration delivered to the patient.

oxygen delivery rate of O2 transport to the peripheral tissues, expressed as Do2, and also referred to as O2 availability or O2 transport; determined by the cardiac output and arterial O2 content.

oxygen exhaust port a opening through which oxygen enriched gas is expelled to the atmosphere.

oxygen extraction ratio derived parameter relating the amount of oxygen removed by the peripheral tissues to the amount contained in the arterial blood, or global oxygen consumption divided by oxygen delivery.

oxygen hood round or rectangular, bottomless, clear rigid plastic device with a half moon-shaped cutout that allows it to be placed over the infant's neck and encloses the entire head. Because only the infant's head is enclosed, the body is accessible for medical and nursing care procedures.

oxygen inlet regulator a pressure control device that governs the pressure of oxygen entering the ventilator system.

oxygen percentage valve a metering device that regulates the proportion of oxygen in the delivered gas.

oxygen system the equipment and devices that distribute, control, and monitor oxygen from the bulk storage unit to the patient site of use.

oxygen tent device used for both oxygen administration and for high humidity therapy. Adult tents were widely used through the 1960s; however, they have been replaced by nasal cannula and masks.

oxygen toxicity the pathological response of the body and its tissues resulting from long-term exposure to high partial pressures of oxygen; pulmonary manifestations include cellular changes causing congestion, inflammation, and edema

oxyhemoglobin the product of combining hemoglobin with oxygen. The loosely bound complex dissociates easily when the concentration of oxygen is low.

oxyhemoglobin equilibrium curve (OEC) nonlinear in vivo relationship between Po2 and O2 saturation; first demonstrated by Paul Bert in 1878; commonly called the oxyhemoglobin dissociation curve.

O2 relay an electronic or mechanical device that controls the flow of oxygen into a delivery system.