The initial logic behind using a single #ventilator to support #multiple #patients is compelling, and speaks to our most basic urge to rescue.
A long thread, to outline challenges that must be solved for it to work in #COVID19
A long thread, to outline challenges that must be solved for it to work in #COVID19
There are certain situations in which it would work well – in patients with fundamentally normal lungs, whose compliance can be easily matched and kept matched, who can be deeply neuromuscularly paralyzed, and ...
for whom there is a plan for individualized ventilators to become available soon to make vent weaning/liberation possible.
(This is important: you can NOT wean multiple patients from a single ventilator, and there has to be a plan for eventual extubation)
(This is important: you can NOT wean multiple patients from a single ventilator, and there has to be a plan for eventual extubation)
If patients with unequal compliance are hooked up to the ventilator, then one will be overdistended (causing worsening lung damage) + the other will be underventilated (causing asphyxiation). Our clinical experience has been that compliance can change significantly in 6-18 hours.
Second, a hallmark of COVID-19 ARDS is marked and disproportionate PEEP responsive, requiring relatively high-levels of PEEP. However, if PEEP is too high, that causes diminished intravascular return, hypotension, and can cause worsening hypoxemia.
PEEP levels in the first several patients I have seen varied between 10 and 24 on similar FiO2. That variation is easily met individually, but would also require matching and dynamic readjustment in a single ventilator / multiple patients situation.
The hallmark of modern effective ventilation is synchronized ventilation allowing sedation reduction and more rapid extubation.
Neither is possible for single ventilator / multiple Patients situation – which means those ventilators are committed to much longer use in that period, reducing the pool of ventilators, so this strategy offers a substantially less than its initially promised doubling of capacity
In sum, single ventilator / multiple patients situation will incur therefore multiple harms to patients:
likely higher tidal volumes (up to 10% absolute increased mortality risk),
lack of daily interruption of sedation (another up to 10% absolute increased mortality risk),
likely higher tidal volumes (up to 10% absolute increased mortality risk),
lack of daily interruption of sedation (another up to 10% absolute increased mortality risk),
prolonged neuromuscular blockade (?50% absolute risk of subsequent disability),
unclear but higher rates of iatrogenic shock,
high rates of post-extubation post-traumatic stress disorder,
+ high rates of ventilator-associated pneumonia with grossly inadequate infection control.
unclear but higher rates of iatrogenic shock,
high rates of post-extubation post-traumatic stress disorder,
+ high rates of ventilator-associated pneumonia with grossly inadequate infection control.
As such, it should rarely be used.
While good data are not available, non-invasive ventilation and heated high flow nasal cannula should be widely and maximally used prior to use of Single ventilator / multiple Patients, as their potential harms are much more theoretical, and where estimated, of much smaller.
In general, we know most Patients would prefer appropriate palliation to a very high risk of disabling, cognitively impairing, PTSD-exacerbating critical care. (Steinhauser et al JAMA + Annals Int Med 2000).
In general, therefore, appropriate palliative care and maximized non-invasive and HHFNC should be preferred.
.@SCCM made similar arguments yesterday, although on more narrowly technical grounds sccm.org/Disaster/Joint…
If you think I'm wrong -- and I would LOVE to be, please go solve the problems of individualizing PEEP, insuring matched compliance over a dynamic course, and potentially (although I have no idea how this could be done) allowing more individualized synchronization
If you can do that, you will save lives
But until we can, my view is that building tools and protocols for #COVID19 single ventilator / multiple patients is a #DISTRACTION from more pressing problems like optimizing PPE, expanding nursing + respiratory therapist capacity, and building safer NIV + HHFNC systems
and we do not have time for distractions
They asked me to expand it a little bit, so there it is as a blog. Thanks to the always generous @precordialthump @LITFLblog
