Venturi mask

The venturi mask, also known as an air-entrainment mask, is a medical device to deliver a known oxygen concentration to patients on controlled oxygen therapy.^[1][2] The mask was invented by Moran Campbell at McMaster University Medical School as a replacement for intermittent oxygen treatment. Dr. Campbell was fond of quoting John Scott Haldane's description of intermittent oxygen treatment; "bringing a drowning man to the surface – occasionally".^[3][4] By contrast the venturi mask offered a constant supply of oxygen at a much more precise range of concentrations.

Adult with air entrainment (Venturi) mask

Use

Venturi masks are used to deliver a specified fraction of inspired oxygen (F_IO₂). 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 F_IO₂. 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_IO₂ is independent of their respiratory pattern.^[5]

A controlled F_IO₂ 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

1. Use of a reservoir nasal cannula in hospitalized patients with refractory hypoxemia; Sheehan, JC, O'Donohue, WJ; Chest. 1996; 110:s1.
2. Bateman NT, Leach RM (1998). "ABC of oxygen. Acute oxygen therapy". BMJ. 317 (7161): 798–801. doi:10.1136/bmj.317.7161.798. PMC 1113909. PMID 9740573.
3. Gibson, G. J. (2004-09-01). "Moran Campbell and clinical science". Thorax. 59 (9): 737–740. doi:10.1136/thx.2004.032219. ISSN 0040-6376. PMC 1747134. PMID 15333847.
4. Sekhar, KC; Rao, SSC Chakra (2014). "John Scott Haldane: The father of oxygen therapy". Indian Journal of Anaesthesia. 58 (3): 350–352. doi:10.4103/0019-5049.135087. ISSN 0019-5049. PMC 4091013. PMID 25024490.
5. Al-Shaikh, Baha; Stacey, Simon (2013). "Masks and oxygen delivery devices". Essentials of Anaesthetic Equipment (4th ed.). Elsevier. pp. 99–110. doi:10.1016/B978-0-7020-4954-5.00006-1. ISBN 9780702049545. Retrieved 3 October 2022.
6. Young, IH (2007). "Revisiting oxygen therapy in patients with exacerbation of chronic obstructive pulmonary disease". The Medical Journal of Australia. 186 (5): 239. doi:10.5694/j.1326-5377.2007.tb00880.x. PMID 17391085. S2CID 27365725.
7. Kittredge P (1983). "Neither Venturi nor Bernoulli". Lancet. 1 (8317): 182. doi:10.1016/s0140-6736(83)92779-4. PMID 6130219. S2CID 10964089.
8. 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.