Percutaneous transtracheal jet ventilation (PTTJV) provides emergency
ventilatory support in patients who cannot be adequately ventilated
with a bag-valve-mask device (with oral or nasal airways) or endotracheally
intubated.1,2 This includes patients with upper airway
foreign bodies or neoplasms, maxillofacial trauma, laryngeal edema,
or infection.2,3 It is also used electively with general
anesthesia for surgery involving the larynx and subglottic areas.4 PTTJV
involves placement of a percutaneous catheter into the trachea and
ventilation via a cyclic delivery of tidal volume to the lungs.5
Early studies of transtracheal ventilation done by Jacoby used
transtracheal catheters connected to 4 to 5 L/min of oxygen.6 Oxygenation
with this apparatus was adequate, but patients quickly developed
hypercarbia due to lack of ventilation.5 This “apneic
oxygenation” also occurs in ventilation through a catheter
attached to a bag-valve device.7 The low pressure and flow
of oxygen generated by the bag-valve device results in increases
in PaCO2 of 4 mmHg/min
and the rapid development of respiratory acidosis.1,8
Numerous studies have since demonstrated that intermittent jets
of pressurized 100% oxygen at 50 pounds per square inch
(psi) allows for both oxygenation and adequate ventilation.8,9 Inspiration
occurs with insufflation of pressurized oxygen through the transtracheal
catheter. Exhalation occurs passively secondary to the elastic recoil
of the lungs and chest wall.10 This passive exhalation
is sufficient to maintain adequate gas exchange.
The anterior neck provides direct access to the airway via the
trachea as it extends from the larynx into the lungs (Figure 13-1).
At the top of the laryngeal skeleton is the thyroid cartilage, which lies
at the level of the fourth and fifth cervical vertebrae. The laryngeal
prominence of the thyroid cartilage (more prominent in men) is easily
palpated with the thumb and index finger. The cricoid cartilage
lies just inferior to the thyroid cartilage at the level of the
sixth cervical vertebra. It serves as the junction of the larynx
and trachea. Multiple cartilaginous rings support the trachea. Between
the cricoid and thyroid cartilages lies the cricothyroid membrane.
The cricothyroid membrane is a palpable membranous depression just
inferior to the laryngeal prominence and is the access site for
PTTJV.11 The cricothyroid artery is a branch of the superior
thyroid artery. It travels transversely across the cricothyroid
membrane just below the thyroid cartilage. Placement of the catheter
through the lower half of the cricothyroid membrane will prevent
injury to this small artery.
Airway structures of the neck.
Once the catheter is placed and appropriately connected to an
oxygen source, oxygen is delivered via bulk flow through the cannula
into the trachea and lungs. Entrainment of room air translaryngeally
via the Venturi principle is negligible, even with minimal upper
airway obstruction.1 Therefore, near 100% ...