This post was going to be called ‘the trouble with NIV’ but it didn’t seem as catchy.
‘Just strap it on and turn it up’ was the educational pearl I once heard an EP say to a reg. To that was added ‘Doesn’t matter what you turn up, as long as you turn it up.’ Smile and exit the room.
While technically true, it’s not very helpful and the end result is the NIV strapped on at ‘5&5’ with the prescribing doc not sure what that means (?EPAP&IPAP ?PEEP&PS) and the administrating nurse equally confused as usually there’s at least two different NIV machines with differing nomenclature and knobs. So something is dialled in and then everyone waits an hour to see what the pH is….
This is analogous to the doc being a front seat passenger and advising the nurse driver to apply a certain pressure (?PSI ?Bar) to the accelerator and checking the emissions in an hour to see if we were driving fast enough.
Here’s another way of looking at it that involves looking at the speedo.
How much IPAP or PS does the patient need? Enough to get a Tidal Volume of 6-8ml/kg ideal body weight.
How much EPAP or PEEP does this patient need? Use the PEEP/FiO2 scale to get as SpO2 of 88-94%.
Lung protective strategy from ARDSnet- minimises both Ventilator Associated Lung Injury and Derecruitment injury. If not, listen to Weingart’s podcasts on ‘Dominating the Vent’.
This approach doesn’t overrule the literature, (which is predominately here’s a disease and here’s some pressures) it actually works with it. In fact, because you can’t do fancy stuff on NIV patients (inspiratory hold for plateau pressure, expiratory hold for intrinsic PEEP), you do have to have a few empirically based rules.
Theory done (and our ICU and Respiratory units are happy with this as a hospital wide approach), you have to read your ventilator’s manual and get the theory to match your machine’s semantics. Here’s the Oxylog 3000 plus and the Savina 300, which are our two machines.
Is there any wonder people were confused?