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 (mV) [mil´ĭ-vōlt]
one thousandth (10−3) of a volt.


Obsolete abbreviation for mendelevium.


Abbreviation for millivolt.


[L.] Med´icus Veterina´rius (veterinary physician).


millivolt; one thousandth (10−3) of a volt.


megavolt; minute volume.


1 abbreviation for megavolt.
2 abbreviation for minute volume.

mv, mV

abbreviation for millivolt.


Abbreviation for megavolt;


(vent?i-la'shon) [ ventilatio, an airing]
1. The movement of air into and out of the lungs.
2. Circulation of fresh air in a room and withdrawal of foul air.
3. In physiology, the amount of air inhaled per day. This can be estimated by spirometry, multiplying the tidal air by the number of respirations per day. An average figure is 10,000 L. This must not be confused with the total amount of oxygen consumed, which is on the average only 360 L/day. These volumes are more than doubled during hard physical labor.

abdominal displacement ventilation

A noninvasive type of artificial ventilation that relies on displacement of the abdominal contents to move the patient's diaphragm.

adaptive support ventilation

Abbreviation: ASV
A mode of mechanical ventilation in which the minute ventilation is not allowed to fall below a set threshold (e.g., in adults, below 100 ml/kg/min), but the inspiratory pressure, inspiratory time, and tidal volume are all adjusted by the ventilator to the patient's needs.

airway pressure release ventilation

A type of mechanical ventilation in which patients breathe spontaneously at any phase of the ventilator's duty cycle at high continuous positive airway pressures (CPAP). Periodically, the level of CPAP is lowered to eliminate waste gases from the circuit.

alveolar ventilation

The movement of air into and out of the alveoli. It is a function of the size of the tidal volume, the rate of ventilation, and the amount of dead space present in the respiratory system. It is determined by subtracting the dead space volume from the tidal volume and multiplying the result by the respiratory rate.

assist-control ventilation

A type of mechanical ventilation with a minimum frequency of respirations determined by ventilator settings. It also permits the patient to initiate ventilation at the same tidal volume or pressure as set on the ventilator.

asynchronous ventilation

In emergency cardiac or critical care, the administration of artificial breaths to a patient that are timed independently of chest compressions.

continuous positive-pressure ventilation

A method of mechanically assisted pulmonary ventilation. A device administers air or oxygen to the lungs under a continuous pressure that never returns to zero.

differential lung ventilation

The use of different ventilatory strategies in each lung in a patient with focal lung disease, e.g., a patient undergoing surgery to remove a tumor in one lobe of a lung but not another, or a patient with more severe COPD on one side of the chest than another. This technique requires a double-lumen endotracheal tube.

dual control ventilation

Mechanical ventilation initiated by either a change in airway pressures or by a change in gas flowing through the ventilator circuit. Dual control is asserted when pressure limited breaths are delivered and the pressure changes from breath to breath to meet a desired delivered tidal volume. It improves the coordination between the patient's respiratory efforts and machine-generated breaths.

high-frequency jet ventilation

A type of ventilation that continuously ventilates at 100 to 150 cycles/min. It is used in respiratory failure to provide continuous ventilation without the side effects of positive-pressure ventilation.

high-frequency oscillatory ventilation

Abbreviation: HFOV
Pulmonary ventilation with multiple rapid breaths given at small tidal volumes. It limits the stretching and collapse of the alveoli that occur in conventional mechanical ventilation.

high-frequency percussive ventilation

Mechanical ventilation that decreases peak and end-expiratory pressure by delivering hundreds of shallow (low tidal volume) breaths per minute. It is a time-cycled, pressure-limited mode of ventilation.

intermittent mandatory ventilation

Abbreviation: IMV
Machine ventilation that delivers pressurized breaths at intervals while allowing for spontaneous breathing.

intermittent positive-pressure ventilation

A mechanical method of assisting pulmonary ventilation, using a device that inflates the lungs under positive pressure. Exhalation is usually passive.
Synonym: breathing, intermittent positive-pressure

inverse ratio ventilation

Abbreviation: IRV
Mechanical ventilation in which the normal temporal relationship between inspiration and expiration is reversed (the inspiration time is longer than the expiratory time). It is sometimes used in severely hypoxemic patients who have not responded to other ventilatory maneuvers. Because it is uncomfortable for patients, paralysis and sedation are needed.

liquid ventilation

A ventilatory technique used to treat both premature infants with surfactant-deficient lungs and adults with acute respiratory distress syndrome.

mandatory minute ventilation

Ventilatory support that provides mechanical breaths when the patient's spontaneous breathing does not achieve the preset mechanical ventilatory rate.

maximum sustainable ventilation

The normal maximum breathing pattern that can be maintained for 15 min (usually approx. 60% of maximum voluntary ventilation).

maximum voluntary ventilation

The maximum amount of gas that can be ventilated into and out of the lungs in a voluntary effort in a given time, measured in liters per minute.

mechanical ventilation

Any form of artificially supplied ventilation.

minute ventilation

Abbreviation: MV
The volume of air inhaled and exhaled in 60 sec. See: minute volume
Enlarge picture

noninvasive ventilation

The use of airway support administered through a face (nasal) mask instead of an endotracheal tube. Inhaled gases are given with positive end-expiratory pressure often with pressure support or with assist control ventilation at a set tidal volume and rate. Numerous studies have shown this technique to be as effective as, and better tolerated than, intubation and mechanical ventilation in patients with exacerbations of COPD.
See: illustration

positive-pressure mechanical ventilation

Mechanical ventilatory support that applies positive pressure to the airway. The objectives include improving pulmonary gas exchange, relieving acute respiratory acidosis, relieving respiratory distress, preventing and reversing atelectasis, improving pulmonary compliance, preventing further lung injury, and avoiding complications. Positive-pressure ventilation can be life saving, but complications such as toxic effects of oxygen, laryngeal injury, tracheal stenosis, alveolar injury, barotrauma, pneumonia, and psychological problems may occur.
See: pressure, positive end-expiratory

pressure support ventilation

A type of assisted ventilation that supplements a spontaneous breath. The patient controls the frequency and the duration and flow of inspiration from the ventilator.

protective ventilation

A type of mechanical ventilation in which tidal volumes are set to avoid overstretching the alveoli, and pressures at the end of an inhaled breath are set to avoid alveolar collapse.

pulmonary ventilation

The inspiration and expiration of air from the lungs.

reduced ventilation

Respiratory depression.

synchronized intermittent mandatory ventilation

Abbreviation: SIMV
Periodic assisted ventilation with positive pressure initiated by the patient and coordinated with spontaneous patient breaths.
See: intermittent mandatory ventilation

transtracheal catheter ventilation

An emergency procedure in which a catheter is placed percutaneously through the cricothyroid membrane and attached to a high-pressure, high-flow jet ventilator. This form of ventilation is used for patients with an upper airway obstruction who cannot be intubated.

volume-controlled ventilation

A form of mechanical ventilation in which the peak inspiratory flow rate, fraction of inspired oxygen, positive end-expiratory pressure, respiratory rate, and tidal volume are preset and delivered to the patient.
Synonym: volume-cycled ventilation; volume-limited ventilation

volume-cycled ventilation

Volume-controlled ventilation.

volume-limited ventilation

Volume-controlled ventilation.

minute ventilation

Abbreviation: MV
The volume of air inhaled and exhaled in 60 sec. See: minute volume
See also: ventilation


[L.] Medicus Veterinarius (veterinary physician).


chemical symbol, mendelevium.