Limitations of the Bag-Valve
The bag-valve mask ventilator is difficult to use
unless the user has had sufficient practice with it. It
must not be used by inexperienced individuals. The
system can be hard to clean and reassemble properly;
the bagging hand can tire easily; and an airtight seal at
the face is hard to maintain, especially if a single
rescuer must also keep the airway open. In addition,
the amount of air delivered to the victim is limited to
the volume that the hand can displace from the bag
(approximately 1 liter per compression).
Procedures for Operating the Bag-Valve
To use the bag-valve mask ventilator, hook the bag
up to an oxygen supply and adjust the flow in the range
of 10 to 15 liters per minute, depending on the desired
concentration (15 liters per minute will deliver an
oxygen concentration of 90 percent). After opening
the airway or inserting an oropharyngeal airway, place
the mask over the face and hold it firmly in position
with the index finger and thumb, while keeping the jaw
tilted upward with the remaining fingers (fig. 4-23).
Use the other hand to compress the bag once every 5
seconds. Observe the chest for expansion. If none is
observed, the face mask seal may not be airtight, the
airway may be blocked, or some component of the
bag-valve mask ventilator may be malfunctioning.
POCKET FACE MASK
A pocket face mask designed with an oxygen-inlet
flow valve for mouth-to-mask ventilation can be used
to give oxygen-enriched artificial ventilation.
Although a pocket face mask system cannot achieve
oxygen concentrations as high as the bag-valve mask
system, it has the advantages of providing greater air
volume (up to 4 liters per breath) and of being much
easier to use (since both hands are free to maintain the
airway and keep the mask firmly in place). See figure
4-24. The pocket face mask also acts as a barrier
device. It prevents the rescuer from coming in contact
with the patients body fluids and breath, which are
possible sources of infection.
To use the pocket face mask, stand behind the head
of the victim, and open the airway by tilting the head
backward. Place the mask over the victims face (for
adults, the apex goes over the bridge of the nose; for
infants, the apex fits over the chin, with the base resting
on the bridge of the nose). Form an airtight seal
between the mask and the face, and keep the airway
open by pressing down on the mask with both thumbs
while using the other fingers to lift the jaw up and back.
Ventilate into the open chimney of the mask.
Figure 4-23.Bag-valve mask ventilator in use.
Figure 4-24.Providing mouth-to-mask ventilations with
pocket face mask.