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role of I E ratio in HFOV

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Dear sir

Normally one starts off with I:E ratio of 1:2 or in some ventilators represented as a percentage like 33%.what it means is if you have selected a frequency of 10Hz( resp rate of 600) then total Ti for a single breath would be 0.03 seconds. Remember that this IE is for each oscillation and not for recruiting breaths (that has a separate entry parameter) 

This conventional 1:2 comes from the expiratory time constant which is twice as long as inspiratory. 

For a given MAP if i am able to manage oxygenation i would not touch on the IE ratio.if you feel that you are not able to maintain oxygenation for a give MAP, in order to recruit more alveolar units one may consider increasing IE to 1:1. But  this might result in issues with ventilation also. It is always better to recruit with titrating MAP rather than I:E


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  • 2 years later...

Like to reactivate this question as it is really from our daily practice .. so like to read more about it . What I can share from our practice 

To change ration 1:2 to be 1:1 is when I have a baby washing CO2, badly with highest frequency possible ( 15), and lowest amplitude with which wiggles can still be evident( we use no less than 15) , so here 1:1 is my next step, in order to limit the CO2 washing , as well help oxygenation, but consider that the case is not already with hyperinflated lungs 🫁, as 1:1 can worsen this part . Again physiology and ogysiodynamics of this depends on the absolute tidal volume delivered.. 

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