<prompt> Fixed performance device:Venturi maskNasal cannulaSimple maskNon rebreathing mask  <response>: Ans: A. Venturi maskRef: Ajar Yadov, Short Textbook of Anesthesia, 1st edition. pg 37.Explanation:Oxygen delivery SystemsOxygen is given thru fixed and variable performance devices.Fixed performance devices deliver a flow of oxygen equal to or in excess of peak inspiratory flowVariable performance devices use the deadspace of the nasopharynx or face masks as a reservoir of oxygen. They cannot deliver high inspired concentrations of oxygen.The oxygen delivery systems are classified into High flow delivery low flow delivery systemsHigh flow delivery systemsThese work on Venturi Principle which states that if a gas is passed through a narrow orifice at high pressure it creates shearing forces around the orifice which entrain room air in specific ratio.The inspiratory gas flow should be 3 - 4 times the minute volumeThese high flow system include venture mask which delivers accurate inspired oxygen FI02 Error is only 1-2Venturi Mask:These are Fixed performance oxygen delivery devices, delivering accurate oxygen concentration.Fixed performance because the performance is not affected by changes in patients tidal volume and respiratory rate.The venture mask are available in different colours:ColourFlow rate of O2 Litre per minDelivered O2FiO2Blue0224White0428Orange0631Yellow0835Red1040Green1560The maximum oxygen that can be delivered by venture mask is 60.Low flow oxygen delivery systemsThese includeNasal cannulaSimple mask Mary Carterall maskOxygen tentsNon rebreathing maskRebreathing maskPoly maskThe advantage is that these are very cheap and can he used in wards, preoperative and postoperative rooms and these are better tolerated by patients as compared to high flow systems.The disadvantage is that the delivered oxygen FiO2 accuracy cannot be predicted Compared to venturi mask which delivers accurate concentrationThese low flow systems are variable performance devices, since their performance is affected by changes in patients tidal volume and respiratory rate.Oxygen Mask: Very commonly used in wards. Also known as Mary carterall maskOxygen flow rateminDelivered oxygen FiO25-6 litres406-7 litres507-8 litres60 So maximum concentration of oxygen that can be delivered by oxygen mask is 60Increasing rate beyond 8 litres will not increase the Fi02 to more than 60 Attaching reservoir bag can increase Fi02 to 80Nasal Cannula: The tip of nasal cannula should lie in nasopharynxFlow rate litreminFiO2124228-332436540644- So. Maximum oxygen w hich can he delivered by nasal cannula is 44Non rebreathing masks: Can deliver upto 80 of oxygenRebreathing mask: When tightly lit. they can provide 100 oxygen 