There is a really smart anesthesiologist out there called Nicholas Chrimes. He along with his mate Peter Fritz invented the Vortex Approach to Airway Management. He also runs a blog called Clinical CrEd.

He did a post advocating the Mapleson B Circuit as the Ultimate Preox Device

What is the Mapleson B? The Mapleson circuits were used for anesthetics in the good old days. At least in the US, we have move to bigger, and arguably better designs for our operative patients. Many would have thought this device would have been consigned to the trash heap, but seemingly not.

from anesthesia 2000

My Recommended Approaches

I recommend two approaches to preox: standard and shunt physiology strategies. I outlines these strategies in the paper Rich Levitan and I wrote.

Standard: NRB @ >=15 lpm and NC @ 10-15 lpm for 3 minutes

Shunt Physio: Choose 1

* BVM with PEEP Valve & NC @ 10-15 lpm

* NIPPV Ventilator with NIPPV Mask or BVM Mask & NC @ 10-15 lpm

Nick makes a number of arguments as to the superiority of the Mapleson circuit over these standard techniques. His points are excellent, but I disagree with pretty much all of them--I think it becomes a question of perspective.

Automatic Checking

Yes, using the same device for reox and preox makes sure the reox device is there and hooked up, but this for me is an inadequate argument to dispense with NRB/NC set-up.

Multiple BVM Masks

We don't have these readily available in any ED or ICU I've worked in. We have neonate, peds, and adult. Our masks also are not inflatable.

PEEP

PEEP is good, Mapleson may or may not be a good way to provide this for the reasons I've mentioned in the wee, but a BVM with a PEEP valve or a vent are at least as good.

ApOx

Mapleson may provide this better than BVM, but not as well as a NC, which should be on during any intubation.

ETCO2

No advantage of Mapleson

Low resistance

Maybe this matters, as soon as you put on the PEEP, I can't imagine this difference persisting

Room Air Entrainment

Release your seal for even one breath and you have blown denitrogenation. Always, always use a strapped system if possible=NRB/NC, NIV mask, or BVM mask with OR straps.

Troubleshooting Leaks

This is the real area in which Nick and I differ. Nick makes the point that a good seal in preox guarantees a good seal in reox--this may be true, but it is unimportant. What I care about is does a bad, one-handed seal in preox mean I won't be able to reox with the BVM--this is entirely untrue. If I did to an awake patient what I will do to them when asleep and desaturating, they would, quite rightfully, punch me in the face.

Anesthesiologists should use Mapleson B/C; ED/ICU should only use BVM +/- PEEP Valve with two hands and oral airway and a rocking triple maneuver (that no pt should experience if they are conscious) otherwise they should be NIV mask with straps or (BVM mask with straps).

This is the same reason I tell my residents to just train with Macintosh blades.

Primary and secondary leaks are the main thrust of Nick's love for the old-timey circuits. But all of us have appreciated this easily by squeezing the bag-valve-mask: Easy-squeezy or Hard Squeezy

ETCO2 with a monitor you can see

Is he holding or squeezing?