The venturi mask, also known as an air-entrainment mask, is a

medical device A medical device is any device intended to be used for medical purposes. Significant potential for hazards are inherent when using a device for medical purposes and thus medical devices must be proved safe and effective with reasonable assura ...

to deliver a known

oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...

concentration to patients on controlled

oxygen therapy Oxygen therapy, also referred to as supplemental oxygen, is the use of oxygen as medical treatment. Supplemental oxygen can also refer to the use of oxygen enriched air at altitude. Acute indications for therapy include hypoxemia (low blood o ...

. The mask was invented by Moran Campbell at

McMaster University Medical School The Michael G. DeGroote School of Medicine, known as the McMaster University School of Medicine prior to 2004, is the medical school of McMaster University in Hamilton, Ontario, Hamilton, Ontario, Canada. It is operated by the McMaster Faculty of ...

as a replacement for intermittent oxygen treatment. Campbell was fond of quoting

John Scott Haldane John Scott Haldane (; 2 May 1860 – 14/15 March 1936) was a Scottish physician physiologist and philosopher famous for intrepid self-experimentation which led to many important discoveries about the human body and the nature of gases. He al ...

's description of intermittent oxygen treatment; "bringing a drowning man to the surface – occasionally". By contrast the venturi mask offered a constant supply of oxygen at a much more precise range of concentrations.

Use

Venturi masks are used to deliver a specified fraction of inspired oxygen (''F_I''O₂). Many masks are color-coded and have a recommended oxygen flow specified on them. When used with this oxygen flow, the mask should provide the specified ''F_I''O₂. Other brands of mask have a rotating attachment that controls the air entrainment window, affecting the concentration of oxygen. This system is often used with air-entrainment nebulizers to provide humidification and oxygen therapy. The total flow of gas (oxygen plus the entrained air) will be greater than the patient's peak inspiratory flow so the delivered ''F_I''O₂ is independent of their respiratory pattern. A controlled ''F_I''O₂ is particularly important for patients whose ventilation is dependent on hypoxic drive, as may be seen in patients with

chronic obstructive pulmonary disease Chronic obstructive pulmonary disease (COPD) is a type of progressive lung disease characterized by chronic respiratory symptoms and airflow limitation. GOLD defines COPD as a heterogeneous lung condition characterized by chronic respiratory s ...

. Administration of too much oxygen may lead to a reduction in their

respiratory rate The respiratory rate is the rate at which breathing occurs; it is set and controlled by the respiratory center of the brain. A person's respiratory rate is usually measured in breaths per minute. Measurement The respiratory rate in humans is mea ...

and retention of carbon dioxide, and ultimately to reduced consciousness or even death.

Mechanism

The mechanism of action is variously described with reference to the venturi effect or

Bernoulli's principle Bernoulli's principle is a key concept in fluid dynamics that relates pressure, speed and height. For example, for a fluid flowing horizontally Bernoulli's principle states that an increase in the speed occurs simultaneously with a decrease i ...

. However, a fixed performance oxygen delivery system works on the principle of jet mixing. Where the flow of moving oxygen meets the static air, viscous shearing causes a predictable amount of the air to be dragged into the flow.

References

{{DEFAULTSORT:Venturi Mask Medical breathing apparatus Medical masks Pulmonological equipment

Use

Mechanism

See also

References