Na+-Nonconducted p Wave

Na+ Symbol for sodium ion.

nano (n) the prefix used in the metric system for billionths. A nanosecond is one billionth of a second

narcolepsy an idiopathic syndrome characterized by sudden sleep attacks

nasal cannula an oxygen delivery device that is characterized by small hollow prongs that insert into the external nares.

nasal catheter an oxygen delivery device consisting of a narrow hollow tubing that is inserted through the nose into the back of the oral cavity.

nasal continuous positive airway pressure (nCPAP) therapeutic support for potential low lung volumes and associated hypoxemia (particularly in infants). nCPAP is also commonly used in the treatment of obstructive sleep apnea (OSA).

nasal flaring dilation of the alar nasi on inspiration; an early sign of an increase in ventilatory demands and the work of breathing, especially in infants

nasal trumpet a type of artificial airway; also called a nasal airway.

nasogastric of or pertaining to the passageway from the nose to the stomach; usually applied to tubes or catheters placed in the stomach through the nose

nasopharyngeal airway plastic or rubber airway device inserted into the nose and directed along the floor of the nose parallel to the hard palate; available as an alternative to the oropharyngeal airway. 

nasopharynx uppermost region of the throat or pharynx, behind the nasal cavity and extending from the posterior nares to the level of the soft palate.

nasotracheal of or pertaining to the passageway from the nose to the trachea; usually applied to tubes or catheters placed in the trachea through the nose, such as a nasotracheal tube, or nasotracheal suctioning  

nasotracheal intubation intubation technique used for specific indications, such as when access to the mouth is to be avoided, in oral surgery or oral trauma, or when the mouth cannot be opened adequately as in trauma, temporomandibular joint (TMJ) dysfunction, or mandibular fixation.

nasotracheal suction maneuver used to remove secretions from the lower respiratory tract.

National Association of Apnea Professionals (NAAP) professional organization of physicians, respiratory therapists, and other medical personnel who provide care for infants with apnea and related disorders.

National Association of Medical Directors of Respiratory Care (NAMDRC) official corporate sponsor of the AARC, as of 1997.

National Asthma Education and Prevention Program expert panel of the National Institutes of Health focusing specifically on the needs of, and programs affecting, individuals with asthma.

National Board for Respiratory Care, Inc. (NBRC) voluntary health certifying board founded in 1960 for the purpose of the evaluation of professional competence for respiratory therapists by providing high-quality voluntary credentialing examinations for respiratory care and pulmonary function technology.

nebulization the production of an aerosol suspension of liquid particles in a gaseous medium using baffling to control particle size

nebulizer a type of aerosol production device that consists of an "atomizer" and a baffle or baffles.

nebulization controls devices on ventilators that regulate the time and/or intensity of the nebulized output.

nebulizer solenoid a switching mechanism that turns the nebulizer on or off.

nebulizer system those parts of a device that produce, control, and deliver aerosols to the patient.

necrosis localized tissue death that occurs in groups of cells in response to disease or injury.

necrotizing pertaining to a process that produces necrosis

needle-capping device a safety device used to prevent or minimize needle stick injuries when capping a syringe needle (as required after blood gas sampling)

NEEP acronym for negative end-expiratory pressure

negative expiratory pressure a mode of ventilation that exerts a small suction during expiration to assist expiratory flow, reduce mean airway pressure, and decrease expiratory time.

negative end-expiratory pressure (NEEP) the application of subatmospheric pressure to the airway during the expiratory phase of positive pressure ventilation

negative extrathoracic pressure a subatmospheric pressure applied to the external chest wall; used in negative pressure ventilators.

negative inotropism a decrease in the contractility of the heart  

negative-pressure capability the ability of a device to generate subambient pressures.

negative-pressure control the mechanism that regulates the application of negative pressures in a device.

negative-pressure jet a Venturi or Pitot device whose purpose is to reduce pressure by air entrainment.

negative pressure ventilation use of a ventilator that applies less than ambient pressure to the external chest wall.

negative-pressure Venturi see "negative pressure jet."

negligence the omission to do something that a reasonable person, guided by those ordinary considerations, would do

neoadjuvant therapy preliminary cancer treatment, such as chemotherapy or radiation, that usually precedes another phase of treatment.

neonatal pertaining to the period between birth and 28 days of age

neoplasia the new and abnormal development of cells that may be benign or malignant

nephron a structural and functional unit of the kidney, resembling a microscopic funnel with a long stem and two convoluted sections

neoplasm, neoplasia, neoplastic abnormal formation of new tissue; can be benign or malignant

neovascularization the formation of new blood vessels

nephron the functioning unit of the kidney or renal tubule

nervous control of the heart emanates from the autonomic nervous system, which includes the sympathetic (adrenergic) and parasympathetic ( cholinergic or vagal) nervous systems, each producing opposite effects when stimulated.

neurocirculatory asthenia a disorder that can occur in soldiers in active war service (and possibly in civilians). It is characterized by a symptom complex that includes breathlessness, a sense of fatigue, precordial chest pain, and palpitation.

neurologic pertaining to neurology or the nervous system

neuromuscular pertaining to the muscle and nerves

neuromuscular blocker chemical substance that interferes locally with the transmission or reception of impulses from motor nerves to skeletal muscles.

neuromuscular disease anyone of a diverse group of disorders ranging from primary muscle diseases that impair all skeletal muscle functions to selected involvement of the diaphragm.

neuropathy any abnormal condition characterized by inflammation and degeneration of the peripheral nerves.

neurosurgery any surgery involving the brain, spinal cord, or peripheral nerves

neurotransmitter a chemical released by the terminal end fibers of an axon

neutral thermal environment environment that provides adequate warmth and humidity to minimize insensible heat and water loss for premature and newborn infants; can be achieved with an incubator or Isolette for a premature, sick, or low-birth weight infant.

neutron particle with no mass but net charge located inside the nucleus of an atom.

neutropenia an abnormal decrease in the number of neutrophils in the blood

neutrophil a polymorphonuclear, granular leukocyte that stains easily with neutral dyes. The nucleus stains dark blue and contains three to five lobes connected by slender threads of chromatin. The cytoplasm contains fine, inconspicuous granules. Neutrophils are the circulating white blood cells essential for phagocytosis and proteolysis by which bacteria, cellular debris, and solid particles are removed and destroyed.

nicotinic pertaining to the effect of acetylcholine at the parasympathetic and sympathetic ganglionic or somatic skeletal muscles receptor sites

nicotinic receptor cholinergic receptor that is sensitive to nicotine acetylcholine, responding to stimulation with electrical depolarization of the muscular cell membranes.

NIPPV abbreviation for noninvasive positive pressure ventilation

nitric oxide colorless gas that is naturally synthesized in human tissue and plays an important role in vascular smooth muscle relaxation, inhibition of platelet aggregation, neurotransmission, and immune regulation.

nitrogen balance study involving a 24-hour urine collection and calculation of the difference between nitrogen intake and excretion; helps determine protein requirements and assess changes in visceral protein store status over time.

nitrogen dioxide (NO2) irritating brownish gas that can be produced spontaneously from NO and O2.

nitroglycerin an explosive used as a vasodilator to relieve angina pectoris and to relieve severe pulmonary congestion and edema (congestive heart failure) secondary to left heart failure. Also used in acute coronary syndromes to enhance coronary blood flow and to reduce ventricular preload by decreasing venous return through venous dilation.

nitrous oxide colorless, odorless, and tasteless gas that can be used with oxygen as an anesthetic; referred to as "laughing gas."

nociceptors nerves that receive and transmit painful stimuli

nocturnal asthma marker for uncontrolled or more severe asthma; includes mechanisms that seem to revolve around circadian alterations of body temperature, vagal tone, mediators, inflammation, epinephrine and β2-receptor function, and possible gastroesophageal reflux, aspiration, sinusitis, increased mucus production, sleep apnea, and the normal decrease in lung function of patients sleeping.

nodoventricular fibers (Mahaim fibers) an accessory conduction pathway located between the lower part of the AV node and the ventricles, resulting in nodoventricular preexcitation.

nodoventricular preexcitation abnormal conduction of the electrical impulses through the nodoventricular fibers, resulting in abnormally wide QRS complexes of greater than 0.10 second in duration and of abnormal shape, with a delta wave. PR intervals are normal.

noise extraneous spikes, waves, and complexes in the ECG signal caused by muscle tremor, 60-cycle AC interference, improperly attached electrodes, and biomedical telemetry­related events, such as out-of-range ECG transmission and weak transmitter batteries.

nomogram a graph consisting of several lines or curves (usually parallel) graduated for different variables in such a way that a straight line cutting the three lines gives the related values of the three variables.

noncompensatory 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. Synonymous with incomplete compensatory pause. See Compensatory pause.

noncompetitive inhibition form of inhibition in which a substance occupies a receptor and cannot be displaced from the receptor by increasing the number of other molecules through the principle of mass action.

nonconducted PAC a positive P' wave (in Lead II) not followed by a QRS complex. A blocked PAC.

nonconducted PJC a negative P' wave (in Lead II) not followed by a QRS complex. A blocked PJC.

nonconducted P wave a P wave not followed by a QRS complex. A dropped beat.

Nonconstant Flow Generator-Numeric Integration Formula

nonconstant flow generator a ventilator that reacts to back pressure and resistance by varying the inspiratory flow pattern.

nonforced vital capacity also called "slow vital capacity." The maximum amount of air that can be slowly exhaled after a maximum inspiration.

noninvasive pertaining to a diagnostic or therapeutic technique that does not require the skin to be broken or a cavity or organ of the body to be entered, as obtaining a blood pressure reading by auscultation with a stethoscope and sphygmomanometer

noninvasive positive pressure ventilation (NIPPV) positive pressure ventilation without endotracheal intubation or tracheotomy, usually via a form-fitting nasal mask

noninvasive ventilation mechanical ventilation performed without intubation or tracheostomy, usually with mask ventilation

nonsynchronized mandatory breath a controlled ventilation that is triggered without respect to the patient's respiratory cycle.

noninvasive positive pressure ventilation (NPPV) mechanical ventilation provided noninvasively (by mask or similar interface) rather than through an endotracheal tube or tracheostomy.

nonlinear having or being a response or output that is not directly proportional to the input.

nonmaleficence principle in which the health care practitioner refrains from harming the patient.

nonpacemaker cell a cardiac cell without the property of automaticity.  

nonparoxysmal junctional tachycardia an arrhythmia orig­inating in an ectopic pacemaker in the AV junction with a rate between 60 and 150 beats per minute. It includes accelerated junctional rhythm (60 to 100 beats per minute) and junctional tachycardia (100 to 150 beats per minute). It may occur with narrow Q RS complexes or abnormally wide QRS complexes because of preexisting bundle branch block or aberrant ventricular conduction. When abnormal QRS complexes occur with the tachycardia because of aberrant ventricular conduction, the tachycardia is called junctional tachycardia with aberrant ventricular conduction (aberrancy).

non protected bronchial brush instrument used for cytologic sampling of proximal airways and central tumors under direct vision or of peripheral lesions under fluoroscopic guidance; a catheter with a brush (open or enclosed in a sheath) at its distal end is introduced through the working channel of the bronchoscope for sampling of proximal airways or central tumors.

non-Q-wave MI a myocardial infarction where abnormal Q waves are absent in the ECG. In the majority of such MIs, a nontransmural MI is present; in the rest it is transmural.

nonrebreathing mask oxygen mask with a one-way valve between the bag and the mask and another one-way valve over one or both mask ports, causing all of the patient's exhaled volume to be directed out of the mask through the mask ports. The valve positioned between the mask and bag prevents exhaled gases from entering the bag.

non-REM sleep stages phases of sleep during which there is an absence of rapid eye movement. Non-REM sleep is subdivided into four stages based on EEG patterns: stages 1 and 2 are considered light sleep, and stages 3 and 4 are termed "deep sleep" or "slow-wave sleep."

nonresectable not removable by surgery

non-small cell carcinoma major category of histologic types of lung carcinomas, including adenocarcinoma of the lung, large-cell carcinoma, and squamous cell carcinoma.

nonsteroidal antiinflammatory drug or agent with antipyretic, analgesic, and antiinflammatory effects to counteract or reduce inflammation by inhibiting prostaglandin synthesis.

nonsustained ventricular tachycardia paroxysms of three or more PVC's separated by the underlying rhythm. Paroxysmal ventricular tachycardia.

nontransmural not extending from the endocardium to the epicardium (i.e., partial involvement of the myocardial wall, either in the subendocardial area or the midportion of the myocardium).

nontransmural myocardial infarction a myocardial infarction in which the ventricular wall is only partially involved by the infarction.

nonvolatile acid an acid that represents either normal dietary acids (primarily the result of protein digestion and metabolism) or lactic and keto acids that are produced as a result of abnormal metabolic pathways.

norepinephrine one of two active hormones (the other is epinephrine) secreted by the adrenal medulla. It is chiefly a vasoconstrictor and has little effect on cardiac output.   .

normal (Gaussian) distribution a distribution for a population of numbers where the majority of numbers have values relatively close to the mean value for the population. This produces what is referred to as a bell-shaped distribution when the values are plotted on a graph.

normal flora bacteria that normally exist in a particular area of the healthy body and which do not usually cause disease at that site.

normal QRS axis a QRS axis between -300 and +900

normal rate control the system that sets the normal breathing frequency on a ventilator.

normal saline incorrect term for the intravenous saline solution containing 0.9% sodium chloride (0.9% saline).

normal sinus rhythm (NSR) normal rhythm of the heart, originating in the SA node with a rate of 60 to 100 beats per minute.

normocapnia a state characterized by a normal partial pressure of carbon dioxide in the arterial blood (35 to 45 torr)

normovolemic a state characterized by normal fluid volumes

nosocomial pertaining to or originating in a hospital, as a nosocomial infection

nosocomial infection an infection acquired after hospitalization. Also called hospital-acquired infection nosocomial pneumonia an infectious inflammatory process of the lung parenchyma that originates in the hospital

nosocomial pneumonia pneumonia that is acquired in the hospital or nursing home.

notch a sharply pointed upright or downward wave in the QRS complex or T wave that does not go below or above the baseline, respectively.

nuchal rigidity: neck stiffness

nucleic acid organic molecule, principally occurring as either deoxyribonucleic acid (DNA) or ribonucleic acid (RNA), that is made from chains of nucleotide, each of which consists of a phosphate group, a 5-carbon sugar, and a nitrogenous base.

numeric integration formula one method for approximating a definite integral; also called the Riemann Sum.