EMS Providers still
use the Bag-Valve Mask device, despite the many years of research which
have conclusively demonstrated that it is a poor performing and
difficult to use resuscitator. We keep using it even though it
delivers low volumes at high flow
rates and high pressures. Every day somebody dies of hypoxia while
being bagged. I often wonder if we use it because
we want to ventilate, or because we have a primal need to
squeeze something. Tidal Volumes with the BVM are typically very low. I
guess nobody was actually meeting the standard of care (10-15cc/kg),
so they lowered it. Completely forgotten is that the volume you deliver
should vary with the patient
Remember that oxygen is a drug. It should be administered in doses
tailored to the size, age, weight of the patient coupled with their
clinical condition. Does the same dose make sense for all adults? No.
How can a BVM address this? It can’t. Most of
our ventilation patients are either in Cardic Arrest or Respiratory
Arrest. They are not hemodynamically stable patients in an ICU bed.
Because they are critically compromised, they need more and not less
recent article in a leading EMS Journal stated that “the lowest
possible pressures and tidal volumes should be used” and that “using
one hand instead of two will help avoid over-ventilation.” By the way,
this was otherwise one of the better pieces written about ventilation
lately. You really cannot "over-ventilate" (meaning deliver excessive
tidal volumes) with any commercially
available device. The maximum volume setting on any EMS Ventilator is
1.2-1.5 liters. The maximum one can deliver with any BVM is less than 1
liter, even two-handed on an ET Tube. A Demand Valve at 40LPM can only
deliver 1.3 liters over a two second inspiratory time. The average
adult lung Vital Capacity is 3 to 5 liters, so how can you
over-ventilate with volumes that are always less? Obviously you can’t.
you can do is use too much pressure. This is directly caused by too
high a flow rate, which is quite common with a BVM. Without any control
over flow rate, pressures can get as high as 60-80cm, well above
esophageal opening pressures of about 20-25cm (or less). This means if
you put the air in too fast, the limited opening of the trachea will
turn these high flow rates into high airway pressures. It’s the high
pressures that cause complications like aspiration, not tidal volume.
is why it is so important to control flow rates, because it is the key
to delivering good tidal volumes safely. We live in a world where
hyperventilation only means “Bag Fast”, when it really means to
“Increase Alveolar Minute Volumes”. Hyperventilation can be done with
either Rate or Volume, or a combination of increasing both. It is not
just rate alone. Going real fast gets you to squeeze faster, resulting
in shorter inspiratory times and higher pressures, which forces air
into the stomach. Then they vomit, aspirate, and die. You can easily
and safely deliver a liter or more of tidal volume IF, you extend the
inspiratory times and control the flow rate to keep the pressures
low. A basic Pocket Mask or Pulmonary Resuscitator can do it, and
better than a BVM. This too has been well documented.
you really must squeeze something rhythmically, please do it in the
privacy of your own home and not on a viable patient. Maybe buy a nice
roll of Charmin to squeeze, and then go buy a decent time cycled,
volume constant ventilator for your patients. Or even just use a Pocket
Mask; hold the seal firmly with two hands, and blow real slow until you
see a nice chest rise. I recently ventilated a patient for over 30
minutes on just room air with a pocket mask type device, to see them
stand up and walk away. NOBODY bagged on an unprotected airway 30
minutes with a BVM ever stands up and walks away.
still like the words of a UK Medic who once said to me (when I commented on the nice ventilator they carried) “Back in the
States, aren’t you guys still zipping them up?” It took a few minutes
before I realized he meant, “bagging them” but on reflection I decided
he did not to be need corrected, I did. Yes, we are still “zipping them up”,
-into body bags. We have stuck our heads in the sands of blissful
ignorance, and steadfastly refused to either learn basic ventilation
mechanics, or any of the many technological advances in ventilation
over the last 25 years.
the AHA also seems ready to abandon emphasis on proper ventilation.
Sure, shock fast is great when the down time is under two minutes, but
when it is longer you better oxygenate the myocardium or you are not
going to get anywhere. To simply abandon efforts to improve emergency
ventilation is only going to get us one thing, more dead people. It’s
time to learn the most important job an EMT or Medic will ever do. It’s
time to say, “We will no longer accept ineffective ventilation technologies and
improper techniques that don’t work”. I’m convinced that a continued
lack of emphasis on ventilation science in EMS is leading us down a
wrong road. I’m not following because I like my clinical saves
way too much.
wise man once said to me, "Keep doing what you have been doing and you will keep
getting what you have been getting." I don’t use BVM’s and I keep getting
What have you been getting?