IPPV with LMA

[Krishnendu Chaudhuri]

Whats the maximum time that you can give positive pressure ventilation through an LMA? Is there a guideline anywhere in the literature?

[jafo1964]

LMA /IPPV - personal experience - 45 mins to 1 hour procedure.
Make sure pt has amodified mallampati class 1 airway so that you can emergently intubate if necessary. I leave out obese pts, GERD and other conditions prone for regurgitation.
Premed always includes H2 receptor antagonists and prokinetics
With classic LMA i limit the inflation pressure to 20. Still experimenting with proseal LMA
Always ensure that with LMA i mandatorily monitor the ETCO2, esp with spont we need to tinker around a bit to keep the values at acceptable levels

I think this is followed in most of the centres

[Krishnendu Chaudhuri]

Reason I asked was I started an inguinal hernia who refused a spinal on an LMA. The surgeon had a few problems and eventually total time was 3 hours. I would have intubated if I had known from before, but the patient came through well and is ok. Question is, was I just lucky or is it OK  to ventilate through an LMA for 3 hours.

by the way, thanks for your input

[jafo1964]

Not totally wrong but a wee bit lucky too.
I ended up doing a radical mastectomy under LMA /CV
No ETCO2
Somewhere along the anaesthetic the LMA must have partially malpositioned
Net result - a hypercarbic patient with delayed recovery
Ofcourse got her out safely
The point is if everything goes well with LMA its OK
but if something goes wrong like minimal aspiration, inadequate ventilation or intra-op laryngospasm then it will be extremely difficult to defend.
We could have intubated the patient which is a definitive airway

[Krishnendu Chaudhuri]

So whats the bottom line? Since we can't guarantee nothing will go wrong, should we not use the LMA under these conditions ???

[jafo1964]

I and the lawyers advising us anaesthesiologists would agree with you
On the other hand i just saw a case of tracheal stenosis today after an uncomplicated ETGA.
really sad and scary
I wonder why we never pay attention to the volume of air we use in our ETT cuffs esp since we use N2O in our balanced anaesthetic technique