Venturi mask
The venturi mask, also known as an air-entrainment mask, is a
Use
Venturi masks are used to deliver a specified fraction of inspired oxygen (FIO2). Many masks are color-coded and have a recommended oxygen flow specified on them.[5] When used with this oxygen flow, the mask should provide the specified FIO2. 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 FIO2 is independent of their respiratory pattern.[5]
A controlled FIO2 is particularly important for patients whose ventilation is dependent on hypoxic drive,[5] as may be seen in patients with chronic obstructive pulmonary disease. Administration of too much oxygen may lead to a reduction in their respiratory rate and retention of carbon dioxide, and ultimately to reduced consciousness or even death.[6]
Mechanism
The mechanism of action is variously described with reference to the venturi effect or Bernoulli's principle.[7] 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.[7][8]
See also
- Oxygen mask for masks used in various settings
References
- ^ Use of a reservoir nasal cannula in hospitalized patients with refractory hypoxemia; Sheehan, JC, O'Donohue, WJ; Chest. 1996; 110:s1.
- PMID 9740573.
- PMID 15333847.
- PMID 25024490.
- ^ ISBN 9780702049545. Retrieved 3 October 2022.
- S2CID 27365725.
- ^ S2CID 10964089.
- ^ Scacci R (1979). "Air entrainment masks: jet mixing is how they work; the Venturi and Bernoulli principles are how they don't". Respir. Care. 24: 928–931.