controlled ventilation

controlled ventilation

n.

Intermittent application of positive pressure to a gas or gases in or about the airway in order to force gas into the lungs in the absence of spontaneous ventilatory efforts. Also called controlled respiration.

---

controlled ventilation,

the use of an intermittent positive pressure breathing unit or other respirator that has an automatic cycling device that replaces spontaneous respiration. Some units measure expired volume, nebulize medication or fluids in the air, exert negative pressure at the end of expiration, or have a variety of alarms.

---

ventilation

renewal or exchange of gas in an enclosed space.

1. the process or act of supplying a building or part of it continuously with fresh air.

2. in respiratory physiology, the process of exchange of air between the lungs and the ambient air. Pulmonary ventilation (usually measured in liters per minute) refers to the total exchange, whereas alveolar ventilation refers to the effective ventilation of the alveoli, where gas exchange with the blood takes place. See also air movement.

---

alveolar ventilation

the amount of gas expelled from the alveoli to the outside of the body per minute.

artificial ventilation

see artificial respiration.

assisted ventilation

the depth of spontaneous ventilation is augmented by the anesthetist, as by squeezing the rebreathing bag.

controlled ventilation

breathing is done entirely by a mechanical device or the anesthetist squeezing the rebreathing bag.

dead space ventilation

see dead space.

high frequency ventilation

mechanical ventilation that delivers gas at more than four times the normal rate of breathing.

intermittent mandatory ventilation (IMV)

a type of mechanical ventilation in which the ventilator is set to deliver a prescribed tidal volume at specified intervals and a high-flow gas system permits the patient to breathe spontaneously between cycles. The ventilator rate is set to maintain the patient's Paco₂ at normal levels and is reduced gradually to zero as the patient's condition improves.

intermittent positive-pressure ventilation (IPPV)

the provision of mechanical ventilation by a machine designed to deliver breathing gas until equilibrium is established between the patient's lungs and the ventilator. IPPV machines are positive-pressure, pressure-cycled, assister-controller (pneumatic) devices.

Because of their compact size and capability of operating independently of an electrical current, the IPPV machines have the most widespread applicability in the employment of a form of treatment called intermittent positive-pressure breathing.

maximal voluntary ventilation (MVV)

the maximal volume that can be exhaled per minute by the patient breathing as rapidly and deeply as possible.

mechanical ventilation

that accomplished by extrinsic means.

minute ventilation

the total amount of gas (in liters) expelled from the lungs per minute.

ventilation mismatch

mismatches of ventilation and blood flow, as in chronic obstructive lung disease, are a common cause of hypoxemia.

ventilation:perfusion ratio

the ratio of air ventilation to the blood perfused. Called also VA/Q. The degree of oxygenation of the blood and the proportional excretion of CO₂ are both dependent on both variables being optimal.

positive pressure ventilation

administration of oxygen under pressure, usually by use of an anesthetic bag or mechanical ventilator. See also continuous positive airway pressure, positive end-expiratory pressure.

spontaneous ventilation

breathing without the assistance of any ventilator or mechanical device.

total ventilation

the amount of air moved out of (or into) the airways and alveoli over a specified time period.