Ventilation Basics

Hi Broomers

Todays vodcast is an introductory talk on the basic physics and physiology of positive pressure ventilation – IPPV or NIV.

For some of you this might be teaching you to suck eggs.  But for me this is full of stuff I wish that I had been taught in my early days of Anaesthesia.

Lets be honest – if you practice elective anaesthesia as a rural doc you spend a lot of time ventilating patients with really good heart and lungs.  This is good – life is not so stressful and our patients do well – great.  However, it does mean we may develop a false sense of security.  Can we manage the trickier cases, the sick lungs, the emergency-can’t back-out cases?

So this talk is about giving you a solid theoretical basis from which you can twiddle the knobs, fine tune, troubleshoot and talk sense to the smart docs in the receiving centre.

Enjoy and let me know if you see any obvious falsehoods or have unanswered questions.  Direct download here

Might do a few shorter talks on specific disease vent strategies.

Also check out the following:

Borrow the OXYLOG  from LITFL


The Crashing Asthmatic from Andy Neill


  1. Tony Wong says

    your talk is absolute gold, thank you. a nice blend of respiratory physiology, relevant equations that is easily applied to clinical practice. just wondering whether a clinical demonstration or pictures of, using a real ventilator either in the NIV or anaesthetic ventilator maybe useful to consolidate the discussion on v/q mismatch, mean airway pressures etc
    thank you again, i’ll keep rewatching it to make sure have squeezed all the good knowledge from it

  2. very good resource Casey , especially for the occasional intensivist out there in the bush!
    Well done!

    I had a tricky ventilated retrieval case this week which reminded me some of the challenges of critical care ventilation in remote areas

    In short its handy to know that moving a ventilated patient stable on say an anaesthetic machine ventilator or ICU ventilator…onto a portable ventilator like the Oxylog3000…does not guarantee ongoing stability!
    The portable ventilators are NOT the not provide the same much more expensive and standard ICU/OT ventilators.

    So assuming that the SAME vent settings on one machine will ensure ongoing stability on another a big ASSUMPTION!

    Derecruitment can often occur especially on ventilation exchange and in particular when the exchanged ventilator does not perform as well as the previous! Think of the disposable vent circult used in the Oxylog 3000 vs the circuit used in say a standard ICU ventilator…then you will understand the differences in performance!

    So be prepared for decrecruitment is lesson number 1 : minimise the time of loss of positive pressure, consider a recruitment maneuver before and soon after exchange, consider clamping ETT during the exchange interval.

    Lesson number 2 = never forget manual ventilation with PEEP valve is good emergency action if ventilation and oxygenation are difficult on the new ventilator initially!

  3. Yep, a few dollars spent on buying PEEP valves for std BMV sets is golden, espec if transferring down corridor from ED/ICU to CT w/o a vent.

    I am still trying to work out tricks on our old Oxylog 2000+ – a stable workhorse, but not as intuitive as the 3000 for eg BiPAP.

    Anyone got any hints? Or wanna trade?

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