Iatrogenic-Inferior Vena Cava

iatrogenic caused by treatment of diagnostic procedures ICP abbreviation for intracranial pressure

ICU,acquired steroid myopathy myopathy acquired in the ICU, becoming an important cause of weakness and contributing to weaning failure from mechanical ventilation.

ideal gas a gas that acts as if it follows all the gas laws exactly.

ideal gas law rule that PV = nRT, with the product of pressure (P) and volume (V) equal to the product of the number of molecules of gas (n), absolute temperature (T), and a gas constant (R).

idiopathic refers to a disease without a known or recognizable cause

idiopathic pulmonary fibrosis (IPF) interstitial lung disease that affects predominantly males in the fifth to seventh decade of life of unknown pathogenesis but likely to reflect an aberrant host response to injury of the alveolar epithelium and endothelium or a protracted response to the same a history of a gradual onset of dyspnea with exercise is typical

idioventricular pertaining to the ventricles.

idioventricular rhythm see Ventricular escape rhythm.

idioventricular tachycardia see Accelerated idioventricular rhythm (AIVR).

I:E ratio inspiratory-expiratory time ratio; the relationship between the inspiratory and expiratory time provided during positive pressure ventilation. Also symbolized as t_I:t_E  

I:E ratio control a ventilator control that regulates the proportions of inspiratory and expiratory time during a respiratory cycle.

I:E ratio limit control a mechanism that prevents I:E ratios below a certain proportion, usually below 1:1.

ileus an obstruction of the intestines, as a dynamic ileus caused by immobility of the bowel, or a mechanical ileus in which the intestine is blocked by mechanical means

iliac crest long curved upper margin of the hip bone.

ILV abbreviation for independent lung ventilation, a mode of ventilation in which each lung receives a different level or type of support

IM Abbreviation for intramuscular.

immaturity the state of being not fully developed or ripened.

immunocompetence the ability of the immune system to defend the body against disease

immunocompromised refers to an immune system incapable of fighting disease

immunocompromised host an immunodeficient patient highly susceptible to infection

immunodeficiency the diminished ability of the immune system to react with appropriate cellular immunity response; often the result of loss of immunoglobulins or aberrance of B or T cell lymphocytes

immunogen an antigen (i.e., a substance capable of stimulating an immune response)

immunoglobulin one of a family of closely related but not identical proteins that are capable of acting as antibodies.  

immunoincompetence immunodeficiency

immunologic mechanism reaction of the body to substances that are foreign or are interpreted by the body as foreign.

immunosuppressive refers to suppressing the body's immune response to antigens

impairment a state that results from an anatomic or functional abnormality. The abnormality is one where medical evaluation identifies a measurable, clinically significant change in body function

impede to slow down; to stand in the way of; to fight against.

impedance (mechanical) the force opposing movement in a mechanical system; as applied to ventilatory mechanics, the sum of the resistive and elastic forces opposing inflation

impedance plethysmography noninvasive study for diagnosing deep venous thrombosis (DVT) by detecting volumetric changes in the limb through changes in the electric impedance.

impedance pneumography method for measuring respiratory rate and excursion using two electrodes placed on the chest wall and then passing a high-frequency and low-ampere AC current between the electrodes on the chest surface.

IMV abbreviation for intermittent mandatory ventilation; periodic ventilation with positive pressure, with the patient breathing spontaneously between breaths. These periodic breaths may be either time-triggered (control mode IMV) or patient-triggered (synchronous intermittent mandatory ventilation, or SIMV)

in situ in the natural or usual place

incentive spirometry technique designed to mimic natural sighing or yawning maneuvers also referred to as sustained maximal inspiration; used to increase transpulmonary pressure and inspiratory volumes to near preoperative vital capacity, improve inspiratory muscle performance, and reestablish the normal pattern of periodic deep breathing.

incidence factor that determines how often a disease or condition is contracted or diagnosed in a time period.

incident report occurrence report filed for an untoward incident in a health care system, such as administration of an incorrect medication or a patient's falling, including specifics such as patient name, identification number, date, time, description of the incident, immediate action taken, and a signature of the reporting employee.

incisura a cut, notch, indentation, or depression; often used to refer to the dicrotic notch observed on the tracing of arterial blood pressure

incomplete AV block (second-degree AV block) an arrhythmia in which one or more P waves are not conducted to the ventricles. See Second-degree, type I AV block (Wenckebach); Second-degree, type II AV block; Second-degree, 2:1 and advanced AV block.

incomplete bundle branch block (right, left) defective conduction of electrical impulses through the right or left bundle branch from the bundle of His to the Purkinje network in the myocardium, resulting in a slightly widened QRS complex (i.e., greater than 0.10 second but less than 0.12 second).

incomplete compensatory pause the R-R interval following a premature contraction that if added to the R-R interval preceding the premature complex would result in a sum less than the sum of two R-R intervals of the underlying rhythm. See Compensatory pause.

incubator apparatus for keeping an infant in an environment of proper humidity and temperature.

indemnity insurance plan type of commercial plan that provides a benefit only if and when a medical event occurs. Indemnity plans provide payment of a fixed sum for a covered benefit.

independent variable variable in a specific function, or relationship, which, in the confines of that function, defines another, dependent, variable.

indeterminate axis a QRS axis between - 90 0 and ± 180 0 (i.e., extreme right axis deviation).

indeterminant error inherent inaccuracy in a measurement.

indifferent, zero reference point see Central terminal.

indirect calorimetry most commonly applied technique for measuring energy requirements in the clinical setting, based on the primary measurement of oxygen consumption (VO2) at the time of measurement, VO2 represents the actual rate of energy expenditure taking place for the measurement period.

indirect-drive piston a ventilator power mechanism wherein the power gas is driven by a piston but does not go to the patient; for example, the power gas may compress a bellows that contains the patient gas volume.

inductance the result of an alternating current passing through a coiled wire. The current produces a magnetic field around the wire that in turn impedes the passage of an electrical current through the wire.

induration hardening of tissue, particularly the skin indwelling located inside the body; commonly refers to invasive diagnostic or therapeutic devices

inert gas narcosis pressure reaction that is analogous to being intoxicated, caused by a pressure greater than 60 fsw, usually occurring in workers in multiplace chambers (which treat more than one individual at a time), particularly while treating divers for arterial gas embolism at depths of 165 fsw.

inert not taking part in chemical reactions; not pharmacologically active

inertia the tendency of an object at rest to stay at rest or a body in motion to stay in motion.

inertial impaction deposition of large aerosol particles on the walls of an airway conduit; inertial impaction is the primary mechanism for deposition of aerosol particles of at least 5 µm and an important mechanism for particles as small as 2 µm.

in-exsufflator a mechanical device that provides an artificial cough by alternately applying positive pressure and negative pressure to the airway

infant apnea program (IAP) treatment component whose recommendations form one of a list of clinical criteria used to consider discontinuation, based on the patient's clinical condition.

infarction death (necrosis) of tissue caused by interruption of the blood supply to the affected tissue.

inferior (diaphragmatic) MI a myocardial infarction commonly caused by occlusion of the posterior left ventricular arteries of the right coronary artery or, less commonly, of the left circumflex coronary artery of the left coronary artery.

inferior vena cava (IVC) venous trunk for the lower extremities and the pelvic and abdominal viscera.

Inferolateral MI-Intraventricular Hemorrhage

inferolateral MI a myocardial infarction that may be caused (1) by occlusion of (a) the laterally located diagonal arteries of the left anterior descending (LAD) coronary artery and/or the anterolateral marginal artery of the left circumflex coronary artery and (b) the posterior left ventricular arteries of the right coronary artery or, less commonly, of the left circumflex coronary artery of the left coronary artery or (2) by occlusion of the left circumflex artery of a dominant left coronary artery.

infiltrate a fluid that passes through body tissues

inflammable the property of igniting and burning easily and rapidly. Also called flammable

inflammation complex, protective immune response of body tissues to irritation or injury in the presence of an antigen or foreign substance.

inflating port an orifice through which ventilating gas flows.

inflation hold maneuver a mechanical breath maneuver that momentarily holds the delivered volume in the lungs under static conditions. An inflation hold may also be used to estimate total compliance and inspiration airway resistance

inflation reflex a vagal response that limits or modulates the pattern of breathing  

influenza an acute, usually self-limiting infectious viral disorder that produces fever, myalgia, headache, and malaise

informed consent right of the patient to all information before undergoing or refusing treatments includes the steps of disclosure, understanding, voluntary nature, competence, and permission giving.

infranodal below the AV node.  

infrared light electromagnetic radiation with wavelengths between 10-5 and 10-4 m; infrared radiation is perceived as heat when it strikes the body

infrequent PVC's less than five PVC's per minute.

infusion administration of a fluid other than blood into a vein.

inguinal of or pertaining to the groin

inguinal ligament a fibrous band formed by the inferior border of the aponeurosis of the external oblique that extends from the anterior superior iliac spine to the pubic tubercle.

inhalation injury sequela of aspiration of superheated gases, steam, or noxious products of incomplete combustion, generating adverse effects on both gas exchange and on hemodynamics.

Inhalation Therapy Association (ITA) association formed in 1946 as a precursor to the American Association of Inhalation Therapists (AAIT) to promote higher standards, professional advancement, to foster cooperation between the technician and physician, and to advance the knowledge of inhalation therapy.

inhaled nitric oxide (iNO) gas shown to improve oxygenation in neonates with hypoxemia and pulmonary hypertension by lowering pulmonary vascular resistance by vasodilating pulmonary vasculature, resulting in decreased right-to-left shunting of blood; selective to pulmonary vasculature and not associated with a lowering of systemic blood pressure.

inherent firing rate the rate at which a given pacemaker of the heart normally generates electrical impulses.

inherent rhythmicity the unique ability of cardiac muscle to spontaneously originate an electrical impulse; also called automaticity

inhibitory repressive; tending to restrain a function.

injector a device that adds a quantity of liquid or gas to a main flow source. See "jet."

innervation function of the nervous system that gives stimulation to a part of the body.

innominate without a name; commonly refers to the innominate artery, also called the brachiocephalic trunk

inoculum substance introduced into the body to cause or to increase immunity to a specific disease or condition.

inotropic agent substance that influences the force of muscular contractions.

INR International Normalized Ratio, the standard measure of the degree of anticoagulation attained by the administration of an anticoagulant such as warfarin. Based on the prothrombin time (PT), the optimal degree of anticoagulation is present when the INR is within the range of 2.0 to 3.0.

insensible water loss the loss of body fluids by means other than through the urinary system, gastrointestinal tract, or sweating; includes evaporative water loss through the lungs and skin

insidious refers to the onset of a disease without symptoms

insomnia inability to sleep

inspiratory capacity (IC) the maximum amount of air that can be inhaled from the resting end-expiratory level or FRC; the sum of the tidal volume and inspiratory reserve volume

inspiratory controls mechanisms that determine the length and timing of inspiratory gas flow.

inspiratory-expiratory (I:E) time ratio the relationship between the inspiratory and expiratory time provided during positive pressure ventilation. Also symbolized as tI:tE

inspiratory flow rate control a ventilator mechanism that sets the volume of gas per unit of time delivered during inspiration.

inspiratory flow time interval from the start of inspiratory flow to the end of inspiratory flow.

inspiratory hold (plateau) a ventilatory maneuver in which the delivered volume of gas is held in the lung for a period prior to allowing expiration. When illustrated as a pressure/time diagram, this is seen as a ledge or plateau at end inspiration.

inspiratory interrupter switch a control device that terminates inspiration.

inspiratory pause time interval from the end of inspiratory flow to the start of expiratory flow.

inspiratory phase respiration phase during mechanical ventilation in which pressure, volume, and flow increase above their end-expiratory values; quantified by specifying the inspiratory time, defined as the time interval from the start of inspiratory flow to the start of expiratory flow, including the hold or pause time.

inspiratory positive airway pressure (IPAP) level of pressure specified on ventilators designed to provide non­invasive positive-pressure ventilation. On such devices IPAP is usually the absolute inspiratory pressure and includes the expiratory pressure. The difference between IPAP and EPAP is the level of pressure support if the EPAP level is changed, the IPAP level must be changed to maintain a constant pressure support level.

inspiratory pressure calibration control allows the inspiratory pressure limit to be set.

inspiratory pressure level the maximum amount of pressure allowed during mechanical ventilation.

inspiratory relief pressure control a device that sets the "pop-off' pressure in a mechanical ventilator.

inspiratory reserve volume (IRV) the maximum volume of air that can be inhaled following a normal quiet inspiration

inspiratory resistance inhalation against some type of resisting force, such as abdominal breathing practice with the pflex or threshold inspiratory muscle trainer  

inspiratory time time interval from the start of inspiratory flow to the start of expiratory flow, including the inspiratory hold (or pause) time.

inspiratory time control sets the length of inspiration either directly or as a fraction of the I:E ratio.

inspiratory time percent the proportion of the respiratory cycle devoted to inspiration.

inspiratory timer a control that determines the time allowed for inspiration.

inspissated (of a fluid) thickened or hardened through the absorption or evaporation of the liquid portion, as can occur with respiratory secretion when the upper airway is bypassed

instantaneous electrical axis or vector a graphic presentation, using an arrow, of the electric current generated by the depolarization or repolarization of the atria and ventricles at any given moment.

instill to introduce a fluid into a body cavity or passage

insufflation blowing of a gas or powder into a tube, cavity, or organ to allow visual examination, to remove an obstruction, or to apply medication

Integrilin trade name for eptifibatide, a GP IIb/IIIa receptor inhibitor.

interatrial conduction tract see Bachmann's bundle.

interatrial septum the partition or wall that separates the right and left atrium of the heart.

intercalated disks specialized structures located at the junctions of the branches of myocardial cells that permit very rapid conduction of electrical impulses from one cell to another.

intercostal of or pertaining to the space between two ribs intercostals referring to the muscle groups between the ribs 

intermittent mandatory ventilation (IMV) a mode of mechanical ventilatory support in which the patient receives a preset number of machine breaths per minute set by time. The patient is allowed to breath spontaneously as often as desired in between machine breaths. Depending on the base rate, IMV can provide partial or full ventilatory support

intermittent percussive ventilation (IPV) therapeutic form of chest physical therapy using a pneumatic device called a Percussionator; the patient breathes through a mouthpiece, which delivers high-flow mini-bursts at rates of over 200 cycles/minute. IPV was designed to treat atelectasis, enhance the mobilization and clearance of retained secretions, and deliver nebulized medications to the distal airways.

intermittent positive pressure breathing (IPPB) short­term or episodic mechanical ventilation for the primary purpose of assisting ventilation and providing short duration hyperinflation therapy; usually administered with pneumatically driven, pressure-triggered, and pressure­cycled ventilators.

intermittent positive-pressure ventilation (IPPV) IPPB done continuously as a form of mechanical ventilation.

internal compressor small compressor linked to a motor within a ventilator and designed for use with a single ventilator.

internal oblique abdominal muscle group that functions as an accessory muscle of ventilation

internal respiration gas exchange between the systemic capillaries and the cells.

internodal atrial conduction tracts part of the electrical conduction system of the heart consisting of three pathways of specialized conducting tissue located in the walls of the right atrium between the SA node and AV node.

interpolated PVC a PVC that occurs between two normally conducted QRS complexes without greatly disturbing the underlying rhythm. A full compensatory pause, commonly present with PVC's, is absent.

interstitial placed or lying between; pertaining to the interstices or spaces within an organ or tissue.

interstitial fluid fluid contained within the interstitial space. This is fluid within the body that is not contained either within the body's cells or within the blood vessels. The concentration of substances within the interstitial fluid is virtually identical to that of the plasma of blood. The only exception is the greater concentration of protein molecules in the plasma.

interstitial lung disease (ILD) term used to delineate approximately 200 distinct diseases in which the interstitium is altered by inflammation and/or fibrosis; may affect any of the following structures: the alveolar walls (and the lumens), pulmonary microvasculature, interstitial macrophages, fibroblasts, myofibroblasts, and matrix components of the lung.

interstitial space the physiologic compartment that lies between the vasculature (blood vessels) and the cells. Substances that pass from the blood into the cells (or the reverse) must pass through the interstitial space.

interstitium the extracellular space

intervals the sections of the ECG between waves and complexes of the ECG. Includes waves, complexes, and segments. See P-P interval, PR interval, QT interval, and R-R interval.

interventricular septum the partition or wall that separates the right and left ventricles of the heart.

intervertebral of or pertaining to the space between any two vertebrae, as the fibrocartilaginous discs

intima the innermost layer lining a blood vessel.

intra prefix meaning within.

intraabdominal within the abdomen

intra-alveolar within the alveoli.

intraaortic balloon pump (IABP) catheter-based balloon inserted into the descending aorta just below the aortic arch and inflated during diastole, causing increased coronary blood flow, and deflated during systole, causing decreased afterload; uses the principle of counterpulsation to support the failing heart, especially in cardiogenic shock due to myocardial ischemia.

intracardiac within the heart.

intracellular fluid (ICF) fluid inside cell membranes that contains dissolved solutes essential to electrolytic balance and healthy metabolism

intracranial with the cranium

intractable incurable or resistant to treatment

intramuscular administration (injection) of a bolus of drug into a muscle bed, where it is taken into the bloodstream by the local capillary bed.

intraoperative within or during a surgical procedure

intrapartum of or pertaining to the period commencing from the onset of labor to the completion of the third stage of labor (expulsion of the placenta)

intrapleural within the pleura.

intrapulmonary within the lungs; often used to refer to alveolar pressure (Palv)

intrapulmonary percussive ventilation (IPV) an airway clearance technique that uses a pneumatic device to deliver a series of pressurized gas mini bursts at high rates (1.6 to 3.75 Hz) to the respiratory tract, usually via a mouthpiece; usually combined with aerosolized bronchodilator therapy

intrarenal within the kidneys.

intrathoracic within the thorax

intratubular within a tube.

intrauterine within the uterus

intravascular within a blood vessel or in the vascular fluid compartment

intravenous route of drug delivery to the inside of a vein; also pertaining to the inside of a vein.

intraventricular conduction disturbance defective conduction of electrical impulses from the AV junction to the myocardium via the bundle branches and Purkinje fibers, resulting in an abnormally wide QRS complex. It occurs most commonly as a right or left bundle branch block and to a lesser extent as a nonspecific, diffuse intraventricular conduction defect (IVCD) seen in myocardial infarction, fibrosis, and hypertrophy; electrolyte imbalance; and excessive administration of certain cardiac drugs.

intraventricular hemorrhage bleeding within a ventricle; can develop in neonates who experience overventilation, hypocarbia, or hyperoxia.

Intrinsic-IVC Filter

intrinsic refers to the essential nature of a substance or structure

intrinsic asthma asthma associated with recent respiratory tract infection inflammatory responses to viral infections (especially lower respiratory tract) may start the cascade of symptomatic wheezing from inflammatory debris or excessive mucus production in the airways.

intrinsic factor a substance normally found in gastric juices; essential for the absorption of vitamin Bl2

intrinsicoid deflection the downstroke of the R wave; the part of the QRS complex that begins at the peak of the last R wave and ends at the J point or tip of the following S wave. Follows the ventricular activation time (VAT) (or preintrinsicoid deflection)

intubation passage of a tube into a body aperture; specifically, the insertion of a breathing tube through the mouth or nose or into the trachea.

intrinsic PEEP (iPEEP) the inadvertent build up of positive pressure in the alveoli due to incomplete exhalation of the inhaled volume. Also called auto-PEEP

in utero in the uterus

invasive characterized by a tendency to spread or infiltrate; also refers to the use of diagnostic or therapeutic methods requiring access to the inside of the body

inverse opposite in order, nature, or effect; being an inverse function.

inverse I:E ratio ventilation mode where the inspiratory time is longer than the expiratory time; for example, I:E is less than 1:1. 

in vitro the occurrence of a biologic process within an artificial environment, that is, outside a living body.

in vivo the occurrence of a biologic process within a living body.  

I/0 abbreviation for intake and output; the recording of a patient's fluid intake and output; may also refer to computer input/output

iodine a nonmetallic element with an atomic weight of 126.904; symbol I.

iodophor an antiseptic or disinfectant that combines iodine with another agent

ion electrically charged atom or group of atoms.

ionic bond stable atomic configurations accomplished by transferring electrons.

IPPB abbreviation for intermittent positive pressure breathing; the application of inspiratory positive pressure, usually with accompanying humidity or aerosol therapy, to a spontaneously breathing patient as a short-term treatment modality, usually for periods of time not exceeding 15 to 20 minutes

IPPV common abbreviation for intermittent positive pressure ventilation, a general term for ventilatory support using positive pressure

iron lung an airtight respirator that consists of a metal tank enclosing the whole body, except the head; the prototype negative pressure ventilator; also known as tank ventilator or Drinker respirator.

irritant receptors vagal sensory sites that respond to irritation of the airways

ischemia decrease in oxygenated blood in a body part or organ in heart disease, this is manifested as changes in the T wave, which reflects abnormalities of repolarization of the myocardium.

ischemic heart disease heart disease caused by a deficiency of the blood supply to the heart (the myocardium, the electrical conduction system, and other structures), caused by obstruction or constriction of the coronary arteries. Manifestations of ischemic heart disease include acute MI, angina pectoris, bundle branch and fascicular blocks, right and left heart failure, and arrythmias.

ischemic necrosis the death or sloughing off of small areas of tissue or bone, caused by insufficient circulation or lack of blood supply

ischemic T waves symmetrically positive and abnormally tall, peaked T waves, or symmetrically and deeply inverted T waves that appear over an ischemic myocardium. Generally, the ischemic T waves are upright over subendocardial ischemia and inverted over subepicardial ischemia.

isobar a line on a map, chart, or nomogram connecting areas of equal pressure.

isoelectric line the flat (sometimes wavy) line in an ECG during which electrical activity is absent. Synonymous with baseline.

isolated beat a premature contraction occurring singly.

isolation precautions safeguards designed to prevent the spread of infectious agents among patients, personnel, and visitors. Isolation precautions may be disease­specific or categorical (grouping diseases that require similar isolation precautions)

isolation protocols infection control measures that combine barrier-type precautions (include handwashing and the use of gloves, masks, and/or gowns) with the physical separation of infected patients in specific disease categories in order to disrupt transmission of pathogenic microorganisms

isothermal the property of maintaining a constant temperature.

isothermic saturation boundary (ISB) the point at which inspired gas is fully saturated at body temperature (44 mg/L at 37° C), approximately 5 cm below the carina at the level of the third-generation airways. Above the ISB, temperature and humidity decrease during inspiration and increase during exhalation; there are no fluctuations in temperature or relative humidity below the ISB.

isotonic property of a solution that occurs with an osmotic pressure that is equal to that found within cells, resulting in a solution with an osmotic pressure equal to that found within cells.

isotope atom whose nuclei have the same number of protons (atomic number) but a different number of neutrons (mass number).

isovolumic having the same volume

isovolumic contraction early phase of systole in which the left ventricle generates enough tension to overcome the resistance of the aortic end-diastolic pressure.

isovolumic relaxation marked decrease in pressure occurring during the first phase of diastole, after aortic valve closure and before mitral valve opening, when the ventricle relaxes without a change in volume.

IV abbreviation for intravenous.

IV bolus a single, relatively large dose of a drug given intravenously.

IV fluids sterile fluids such as 0.9% saline or Ringer's lactate solution administered intravenously.

IV line a catheter or needle, a solution administration set, and an intravenous solution used to administer drugs and fluids intravenously.

IVC filter filter placed in the inferior vena cava to prevent lower extremity thrombus from embolizing to the lungs; primary indications for filter placement include contraindications to anticoagulation, recurrent embolism while on adequate therapy, and significant bleeding complications during anticoagulation.