system, it has the advantages of providing greater
air volume (up to 4 liters per breath), and being
far easier to use since both hands can be used to
maintain the airway and keep the mask firmly in
place (fig. 4-15).
TECHNIQUE. Standing behind the head of
the victim, 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 for the mask 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. The corpsman then ventilates
into the open chimney of the mask.
Oxygen can be added by hooking the valve up
to an oxygen supply. Since the oxygen flow will
be diluted by the rescuers breath in artificial ven-
tilation, the flow rate will have to be adjusted to
increase oxygen concentration. At 5 liters per
minute, the oxygen concentration will be approx-
imately 50 percent. At 15 liters per minute, this
will increase to 55 percent.
The mask has an elastic strap so it can be used
on conscious self-ventilating patients to increase
Esophageal Obturator Airway (EOA)
An EOA is a semi-flexible large-bore tube ap-
proximately 30 cm in length, with 19 holes in the
shaft and an inflatable cuff. A soft face mask is
attached to one end and the other end is closed.
The airway was designed for personnel who are
not authorized to place endotracheal tubes. One
of the distinct advantages is that it can be inserted
blindly through the mouth without having to
visualize the larynx. It is also helpful in the preven-
tion of gastric regurgitation. The disadvantages
are that the tracheo-bronchial tree cannot be ade-
quately suctioned and there is the possibility of
esophageal rupture when the cuff is inflated too
The following steps are to be followed when
inserting the EOA:
1. Hyperventilate the patient.
2. Position the head in a neutral position or
slightly flexed. DO NOT hyperextend the
3. Lift the jaw as in figure 4-16A.
4. Insert the tube until the mask is flush with
the face as in figure 4-16B.
Figure 4-15.Mouth-to-mask breathing.
Ventilate through the tube and auscultate
both lung fields. The EOA is sometimes in-
serted into the trachea; this is of little worry
if recognized and corrected immediately.
Inflate the cuff (about 35cc of air).
Overinflation can possibly rupture the
esophagus or may compress the trachea
causing an obstruction.
Ventilate and auscultate again to ensure
A cricothyroidotomy, often known as an
emergency tracheotomy, consists of incising the
cricothyroid membrane, which lies just beneath
the skin between the thyroid cartilage and the
cricoid cartilage. The cricothyroid membrane can
be located easily in most cases. Hyperextend the
neck so that the thyroid notch (Adams apple)
becomes prominent anteriorly. Identify the posi-
tion of the thyroid notch with the index finger.
This finger descends in the midline to the promi-
nence of the cricoid cartilage. The depression of
the cricothyroid membrane is identified above the
superior margin of the cricoid cartilage (fig. 4-17).
A small lateral incision is made at the base of the
thyroid cartilage to expose the cricothyroid mem-
brane. This membrane is then excised, taking