A medical ventilator is a machine designed to provide mechanical ventilation by moving breathable air into and out of the lungs, to deliver breaths to a patient who is physically unable to breathe, or breathing insufficiently.
Tidal volume is the lung volume representing the normal volume of air displaced between normal inhalation and exhalation when extra effort is not applied. In a healthy, young human adult, tidal volume is approximately 500 mL per inspiration or 7 mL/kg of body mass.
A negative pressure ventilator, also known as iron lung (colloquialism) or pulmotor, is a mechanical respirator which enables a person to breathe on his or her own in a normal manner, when muscle control is lost, or the work of breathing exceeds the person's ability. Need for this treatment may result from certain diseases and certain poisons.
Barotrauma is physical damage to body tissues caused by a difference in pressure between a gas space inside, or in contact with, the body, and the surrounding gas or fluid. The initial damage is usually due to over-stretching the tissues in tension or shear, either directly by expansion of the gas in the closed space or by pressure difference hydrostatically transmitted through the tissue. Tissue rupture may be complicated by the introduction of gas into the local tissue or circulation through the initial trauma site, which can cause blockage of circulation at distant sites or interfere with normal function of an organ by its presence.
Spirometry is the most common of the pulmonary function tests (PFTs). It measures lung function, specifically the amount (volume) and/or speed (flow) of air that can be inhaled and exhaled. Spirometry is helpful in assessing breathing patterns that identify conditions such as asthma, pulmonary fibrosis, cystic fibrosis, and COPD. It is also helpful as part of a system of health surveillance, in which breathing patterns are measured over time.
Artificial ventilation, is means of assisting or stimulating respiration, a metabolic process referring to the overall exchange of gases in the body by pulmonary ventilation, external respiration, and internal respiration. It may take the form of manually providing air for a person who is not breathing or is not making sufficient respiratory effort on their own, or it may be mechanical ventilation involving the use of a mechanical ventilator to move air in and out of the lungs when an individual is unable to breathe on their own, for example during surgery with general anesthesia or when an individual is in a coma.
Dual-control modes of ventilation are auto-regulated pressure-controlled modes of mechanical ventilation with a user-selected tidal volume target. The ventilator adjusts the pressure limit of the next breath as necessary according to the previous breath's measured exhaled tidal volume. Peak airway pressure varies from breath to breath according to changes in the patient's airway resistance and lung compliance.
Positive end-expiratory pressure (PEEP) is the pressure in the lungs above atmospheric pressure that exists at the end of expiration. The two types of PEEP are extrinsic PEEP and intrinsic PEEP. Pressure that is applied or increased during an inspiration is termed pressure support.
High-frequency ventilation is a type of mechanical ventilation which utilizes a respiratory rate greater than four times the normal value. and very small tidal volumes. High frequency ventilation is thought to reduce ventilator-associated lung injury (VALI), especially in the context of ARDS and acute lung injury. This is commonly referred to as lung protective ventilation. There are different types of high-frequency ventilation. Each type has its own unique advantages and disadvantages. The types of HFV are characterized by the delivery system and the type of exhalation phase.
Ventilator-associated lung injury (VALI) is an acute lung injury that develops during mechanical ventilation and is termed ventilator-induced lung injury (VILI) if it can be proven that the mechanical ventilation caused the acute lung injury. In contrast, ventilator-associated lung injury (VALI) exists if the cause cannot be proven. VALI is the appropriate term in most situations because it is virtually impossible to prove what actually caused the lung injury in the hospital.
Pressure support ventilation (PSV), also known as pressure support, is a spontaneous mode of ventilation. The patient initiates every breath and the ventilator delivers support with the preset pressure value. With support from the ventilator, the patient also regulates his own respiratory rate and tidal volume.
In medicine, the mean systemic pressure is defined as the mean pressure that exists in the circulatory system when there is no blood motion. The value of MSP in animal experimental models is approximately 7 mm Hg. It is an indicator of how full the circulatory system is, and is influenced by the volume of circulating blood and the smooth muscle tone in the walls of the venous system .
Airway pressure release ventilation (APRV) is a pressure control mode of mechanical ventilation that utilizes an inverse ratio ventilation strategy. APRV is an applied continuous positive airway pressure (CPAP) that at a set timed interval releases the applied pressure. Depending on the ventilator manufacturer, it may be referred to as BiVent. This is just as appropriate to use, since the only difference is that the term APRV is copyrighted.
A liquid ventilator is similar to a medical ventilator except that it should be able to ensure reliable total liquid ventilation with a breatheable liquid ·. Liquid ventilators are prototypes that may have been used for animal experimentations but experts recommend continued development of a liquid ventilator toward clinical applications.
Modes of mechanical ventilation are one of the most important aspects of the usage of mechanical ventilation. The mode refers to the method of inspiratory support. In general, mode selection is based on clinician familiarity and institutional preferences, since there is a paucity of evidence indicating that the mode affects clinical outcome. The most frequently used forms of volume-limited mechanical ventilation are intermittent mandatory ventilation (IMV) and continuous mandatory ventilation (CMV). There have been substantial changes in the nomenclature of mechanical ventilation over the years, but more recently it has become standardized by many respirology and pulmonology groups. Writing a mode is most proper in all capital letters with a dash between the control variable and the strategy
Continuous mandatory ventilation (CMV) is a mode of mechanical ventilation in which breaths are delivered based on set variables. Still used in the operating room, in previous nomenclature CMV referred to "controlled mechanical ventilation", a mode of ventilation characterized by a ventilator that makes no effort to sense patient breathing effort. In continuous mandatory ventilation, the ventilator can be triggered either by the patient or mechanically by the ventilator. The ventilator is set to deliver a breath according to parameters selected by the operator. "Controlled mechanical ventilation" is an outdated expansion for "CMV"; "continuous mandatory ventilation" is now accepted standard nomenclature of mechanical ventilation. CMV today can assist or control dynamically, depending on transient presence or absence of spontaneous breathing effort. Thus, today's CMV would have been called ACV in older nomenclature, and the original form of CMV is a thing of the past. But despite continual technological improvement over the past half century, CMV sometimes may still be uncomfortable for the patient.
Many terms are used in mechanical ventilation, some are specific to brand, model, trademark and mode of mechanical ventilation. There is a standardized nomenclature of mechanical ventilation that is specific about nomenclature related to modes, but not settings and variables.
Intermittent Mandatory Ventilation (IMV) refers to any mode of mechanical ventilation where a regular series of breaths are scheduled but the ventilator senses patient effort and reschedules mandatory breaths based on the calculated need of the patient. Similar to continuous mandatory ventilation in parameters set for the patients pressures and volumes but distinct in its ability to support a patient by either supporting their own effort or providing support when patient effort is not sensed. IMV is frequently paired with additional strategies to improve weaning from ventilator support or to improve cardiovascular stability in patients who may need full life support.
Mechanical power is a medical term which is a measure of the amount of energy imparted to a patient by a mechanical ventilator.
