Editing Ventilator (section)

==Function==
[[File:Ventilators.jpg|thumb|A standard setup for a ventilator in a hospital room. The ventilator pushes warm, moist air (or air with increased oxygen) to the patient. Exhaled air flows away from the patient.]]
In its simplest form, a modern [[positive pressure ventilation|positive pressure ventilator]], consists of a compressible [[air]] reservoir or turbine, air and [[oxygen]] supplies, a set of valves and tubes, and a disposable or reusable "patient circuit". The air reservoir is pneumatically compressed several times a minute to deliver room-air, or in most cases, an air/oxygen mixture to the patient. If a turbine is used, the turbine pushes air through the ventilator, with a flow valve adjusting pressure to meet patient-specific parameters. When over pressure is released, the patient will exhale passively due to the [[lung]]s' elasticity, the exhaled air being released usually through a [[one-way valve]] within the patient circuit called the patient manifold.

Ventilators may also be equipped with monitoring and alarm systems for patient-related parameters (e.g., pressure, volume, and flow) and ventilator function (e.g., air leakage, power failure, mechanical failure), backup batteries, oxygen tanks, and remote control. The pneumatic system is nowadays often replaced by a computer-controlled [[turbopump]].

=== Ventilator pressures labeled ===
[[File:Ventilator pressures labeled.png|thumb|Ventilator pressures labeled]]
Modern ventilators are electronically controlled by a small [[embedded system]] to allow exact adaptation of pressure and flow characteristics to an individual patient's needs. Fine-tuned ventilator settings also serve to make ventilation more tolerable and comfortable for the patient. In Canada and the United States, [[respiratory therapists]] are responsible for tuning these settings, while biomedical technologists are responsible for the maintenance.  In the United Kingdom and Europe the management of the patient's interaction with the ventilator is done by [[Critical care nursing|critical care]] nurses.

The patient circuit usually consists of a set of three durable, yet lightweight plastic tubes, separated by function (e.g. inhaled air, patient pressure, exhaled air). Determined by the type of ventilation needed, the patient-end of the circuit may be either noninvasive or invasive.

Noninvasive methods, such as [[Continuous positive airway pressure|continuous positive airway pressure (CPAP)]] and [[non-invasive ventilation]], which are adequate for patients who require a ventilator only while sleeping and resting, mainly employ a nasal mask. Invasive methods require [[intubation]], which for long-term ventilator dependence will normally be a [[tracheotomy]] cannula, as this is much more comfortable and practical for long-term care than is larynx or nasal intubation.<gallery widths="300" heights="200">
File:Closed circuit ventilators.gif|Closed circuit ventilator system are used to provide O<sub>2</sub>-enriched air to the patient.
File:Open circuit ventilator.gif|Open circuit ventilators are used to provide normal ambient air with normal O<sub>2</sub> ratio to the patient.
File:Biology of ventilation.gif|At physiological level, ventilators renew the [[Atmosphere of Earth|air]] and its critical [[Breathing|O<sub>2</sub>/CO<sub>2</sub> exchange]] to [[pulmonary alveolus]]. 
</gallery>

=== Safety-critical system ===
As failure may result in death, mechanical ventilation systems are classified as [[safety-critical system]]s, and precautions must be taken to ensure that they are highly reliable, including their [[power-supply|power supply]]. Ventilatory failure is the inability to sustain a sufficient rate of CO<sub>2</sub> elimination to maintain a stable pH without mechanical assistance, muscle fatigue, or intolerable dyspnea.<ref>Marini, John J., Dries, David J... ''Critical Care Medicine: The Essentials and More''. 5th Edition. Two Commerce Square, 2001 Market Street, Philadelphia, PA 19103 USA:Lippincott Williams & Wilkins; 2019.  Available from: Books@Ovid at http://ovidsp.ovid.com.  Accessed January 12, 2021.</ref> Mechanical ventilators are therefore carefully designed so that no [[single point of failure]] can endanger the patient. They may have manual backup mechanisms to enable hand-driven respiration in the absence of power (such as the mechanical ventilator integrated into an [[anaesthetic machine]]). They may also have safety valves, which open to atmosphere in the absence of power to act as an anti-suffocation valve for spontaneous breathing of the patient. Some systems are also equipped with compressed-gas tanks, air compressors or backup batteries to provide ventilation in case of power failure or defective gas supplies, and methods to operate or call for help if their mechanisms or software fail.<ref>{{cite news |last1=Johnson |first1=Carolyn Y. |last2=Cha |first2=Ariana Eunjung |title=The dark side of ventilators: Those hooked up for long periods face difficult recoveries |url=https://www.washingtonpost.com/health/2020/04/03/coronavirus-survivors-recovery |access-date=8 April 2020 |newspaper=[[The Washington Post]] |language=en}}</ref>  [[Power outage|Power failures]], such as during a natural disaster, can create a life-threatening emergency for people using ventilators in a home care setting.<ref name=":3">{{Cite web|last=Huff|first=Charlotte|date=2021-05-12|title=The People in Danger the Minute the Power Goes Out|url=https://slate.com/technology/2021/05/climate-change-power-grid-home-medical-care-electricity.html|access-date=2021-05-18|website=[[Slate (magazine)|Slate]]|language=en}}</ref>  Battery power may be sufficient for a brief loss of electricity, but longer power outages may require going to a hospital.<ref name=":3" />